8 IMPACTS AND MITIGATION: THE NATURAL ENVIRONMENT N2 Bypass EIR (Pg 109- 294).pdf · 8 IMPACTS AND MITIGATION: THE NATURAL ENVIRONMENT ... the central section which is common to both

Volume 2: EIA Specialist Volume – Executive Summary

Coastal & Environmental Services 109 Knysna N2 Toll Road

8 IMPACTS AND MITIGATION: THE NATURAL ENVIRONMENT 8.1 Introduction The subsections which follow discuss the potential impacts of the Knysna Toll Highway on three main aspects of the Natural Environment. In the case of the Erosion Impacts, as there is only one impact, the discussion focuses on the relative significance of this potential impact for various sections and features of the highway. For ease of comparison between the alternatives, the highway has been divided up into three sections – 1) the central section which is common to both the ‘Proposed’ and the ‘Short’ routes, 2) the western section from Buffelsvermaak to the Eastford interchange, and 3) the eastern section from the Uniondale Interchange to Brackenhill. The western and eastern sections had different routes for the ‘Proposed’ and ‘Short’ routes. In the case of the Estuary and Aquatic aspect of the environment, there are many potential impacts, but they are all relevant to the Western section of the ‘Proposed’ and ‘Short’ routes only. There are also many impacts on the terrestrial Ecology and again the extent to which these are relevant to the common central section or the western or eastern portions of the ‘Proposed’ and ‘Short’ Routes are assessed. The extent to which these impacts are relevant to the construction and operational phases is indicated but generally most of the impacts on the natural environment occur during the operational phase. As the ‘Do Nothing’ and the ‘Do Minimum’ alternatives will involve no removal of vegetation or disturbance of natural areas these alternatives largely have no impacts on the natural environment. 8.2 Erosion Impacts The major determinants of erosion potential are the types of soils and the steepness of the slope. In the Knysna area both of these characteristics contribute to a significant risk of soil erosion associated with new developments such as the proposed Knysna toll highway. These two characteristics, the steepness of the slopes and the nature of the soils, have been used in this study to assess the potential risk of soil erosion along various segments of the proposed Knysna highway and its alternatives. Table 8.1 below indicates how the combination of steepness and soil type is expected to result in particular severities of erosion risk. Figures 8.1-3 illustrate the results of the erosion risk assessment along the Highway alignments. Table 8.1: Matrix to assess the ‘Severity’ of the erosion hazards

Degree of Slope Very Steep Moderately Steep Slight Slope Flat

Soil Type

>28º (degrees) 20-27º 0 to 19º 0 º Cover Sands

Very Severe Severe Moderate to low Severity

No impact

Fine and interbedded Enon Conglomerate

Severe Moderately Severe Slightly Severe No impact

Course Enon Conglomerate (further from the fault line)

Moderately Severe

Slightly Severe No impact No impact

8.2.1 General Mitigation methods for Erosion impacts The extent to which erosion risks/impacts can be mitigated also varies depending on the severity of the risk/impact and the type of soils. The matrix provided in table 8.2 below indicates the degree to which it is difficult to manage and mitigate these erosion impacts. In the subsections which follow, the appropriate mitigation measures for each category of erosion risk are outlined.



Table 8.2 Extent to which these impacts can be mitigated Severity of Potential Erosion Impact Soil Type

Very Severe

Severe Moderate Severity

Low Severity

Cover Sands

Extremely Difficult

Difficult Moderately Difficult

moderate

Fine and interbedded Enon Conglomerates

Difficult Moderately Difficult

Relatively Easy Simple

Course Enon Conglomerates Difficult Moderately Difficult

Relatively Easy Simple

Mitigation Measures for Enon Conglomerates Each cutting through Enon conglomerate should be evaluated separately from a geological and soil composition point of view in order to determine the correct method and measures of stabilization needed. The cuttings through the Enon Conglomerate should be made at relatively low angles (less than 25 degrees slope), if possible, in order to allow a topsoil cover to spread and stabilised. As the risk of failure is lower than over cover sands, rehabilitation could be carried out using the appropriate indigenous plant species. Slopes above cuts into the conglomerate must be carefully evaluated and treated to prevent water penetration that could cause shifts in the strata. Well designed and protected cut-off drains could be used as one of the water management options, however, vegetation cover remains a good management tool.

Figure 8.1: Results of erosion risk assessment for the western section of the Knysna Toll Highway



Figure 8.2: Results of erosion risk assessment for the western half of the central section of the Knysna Toll Highway

Figure 8.3: Results of erosion risk assessment for the eastern half of the central section and the eastern section of the Knysna Toll Highway Particular care should be taken to avoid cuts that may allow water to migrate horizontally along more permeable layers. Any change in the water regime of these conglomerates tends to shift problem areas from one locality to the next.



Mitigation Measures for Cover Sands Permanent drainage above road cuttings will be critical for cover sand areas. Soil and geological profiles will need to be well understood. Where impermeable horizons are present in the profile, these will need to be drained in addition to the surface drainage. Slope stabilization using the appropriate measures is critical. In some areas it will not be sufficient to stabilise and plant with indigenous species, as the slopes will be under threat for at least two seasons before adequate root growth has occurred to provide stability. In areas of deep cuts into cover sands, total cover using grass sods may be necessary. These sands are very nutrient poor and re-vegetation is a significant problem. It is also important to realise that cover sands usually carry very shallow fertile topsoil layers. Rehabilitation of road reserves with vegetation becomes extremely problematic due to the low fertility of these red cover sands. Topsoil must be removed and stored very carefully in order to have some fertile cover for the cut and fill areas. It is strongly recommended that large cuts in cover sands be avoided wherever possible, as these soils are particularly vulnerable to erosion during construction periods and there is almost always expensive maintenance that has to be done to cuts on steep slopes. Piping is a real problem (on cover sands) and should be prevented with suitable methods. This could include vegetation, chemical treatment, compaction and other methods listed in section 6.4 below. Cover sands must be re-vegetated as soon as possible. Particular care must be taken in such areas to avoid the possibility of siltation of the small wetlands in this area. Geotextile curtains above and below road excavations and fill areas could assist in the control of erosion products. It is not advisable to attempt construction on severe risk areas (i.e. on cover sands with steep slopes), but should attempts be made to carry on with construction regardless of warnings, the relevant mitigation measures listed in section 6.4 below should be adopted as a minimum. Mitigation Measures for Steep slopes Avoid areas where steep slopes (Gradients greater than 28 degrees can be considered steep for the purpose of this discussion) occur, the erosion potential is very high and the rehabilitation potential is very low. Steep slopes do not hold water long enough for significant plant growth. Cover sands and Enon conglomerates are known to be nutrient deficient. The Garden Route is well known for low nutrient content of these soils. Soil acidity is also high. There is also a good/strong possibility of slumping on these denuded slopes. The Simola Road is a good example of where such slumping and consequent siltation in the Salt River, and subsequently the Knysna Lagoon, was severe. If it is not possible to avoid such areas, the road should be situated on the ridges and spurs. Cutting into cover sand areas should be avoided or minimized. Retaining measures such as gabions are often not adequate to stabilize the slopes and prevent erosion. Heavy structures imposed upon such slopes tend to create slips rather than prevent them. Particular care should be taken to disperse the runoff efficiently. Drainage of fill areas behind retaining structures is particularly important. Consequently, storm water control measures should be incorporated in the Environmental Management Plan (EMP) and the structures should be monitored regularly. General Construction Phase Mitigation Measures In addition to the mitigation measures suggested for particular soil types and slopes discussed above, the following general mitigation methods should be adopted during the construction phase:



• Most Importantly – Avoid or minimise the removal of the natural vegetation cover • Save all topsoils for later use. • Use agricultural drainage methods in fill materials to remove water that could trigger

slumping. • Identify perched water tables early and provide adequate drainage for these trigger points • Prevent the disturbance of the natural soil structure. Plan excavations carefully and avoid

moving heavy machinery into areas unnecessarily. • All fill material must be very well compacted and innovative use of geo-textile materials in

the retention of soil fill areas will prove to be money well spent • Keep rainwater runoff from cut slopes as far as possible. • Create cut off drains in areas above cut slopes. Ensure that cut off drains are lined in such

a way that they do not create, rather than, alleviate problems. • Create enough storm water take off points along the route in such a way that water does

not have an opportunity to gather momentum. • Storm water ditches should contain structures that will reduce velocity of the run off • Use of vegetated swales should be investigated in less steep areas. • Ensure that infrastructure such as water and sewerage reticulation lines are kept far from

the road reserve. Leaks on slopes near the road have caused unwanted repairs when slumps occur.

• Provide protected conduits for concentrated runoff • Do not EVER allow stormwater to exit on to unprotected cover sand slopes. • Any suitable geotextile must be used to prevent erosion products from washing away • Suitable soil stabilising chemicals could be applied in some cases where stabilisation of

road substrate is necessary. • Large cuts with longer slopes can possibly be broken up into shorter sections through

stepped gabion walls with efficient agricultural drainage methods to drain any water that is caught behind the structures. This method is vulnerable if the appropriate geotextile is not applied. The migrant silt particles tend to clog pores of the textiles and the damming can develop behind the gabions. The application of these structures and textiles should be informed by a detailed analysis of the soil structure and water regime of the particular site. Heavy retaining structures combined with bad drainage may cause catastrophic collapses during heavy storm conditions.

• Refer to the slope analysis to determine suitable angles of repose for slopes. These guidelines were developed over time by companies such as Outeniqua lab, and should be taken as a guide and not an absolute as the cover sand particle sizes tend to vary from site to site.

• The use of onion bags filled with absorbent organic material to protect slopes is recommended where possible

• The use of mulched vegetation on newly exposed slopes may prove beneficial when a product such as “ hydromulch “is applied.

• Newly applied topsoil will also benefit from mulching. • Vegetate any cut surfaces as soon as possible using local indigenous materials • Only local indigenous vegetation should be used for mulching. This will increase the

possibility of restoring natural vegetation to cut surfaces. • In areas where high density ground cover is required, indigenous Buffalo grass should be

considered in preference to Kikuyu. • Avoid using trees and large shrubs on restructured cover sand slopes. Plants with large

root masses tend to agitate and mobilise slopes during wet windy weather. These plants tend to trigger, rather than prevent slumping.

Mitigation measures against erosion and collapse of cover sands are the same for virtually any slope (see section 4.5.1 in the Specialist Volume Part 1). The above mentioned measures can, in most cases also be applied to the Enon substrates.



Operational Phase Mitigation Measures

Mitigation of impacts during the operational phase of the road will consist mainly of maintaining the various protective measures that were installed during the construction phase. This will entail the following:

• Vegetation of road verges and cut faces must be inspected and maintained on a regular basis. This is particularly important on steep slopes.

• Water runoff conduits and stormwater swales must be monitored for undercutting and piping. Any sign of deterioration must be attended to promptly as inadequate spillways tend to erode on the soft edges of the structures, causing undercutting and collapse.

• Any new activity such as installation of underground services should be scrutinised for possible impacts on the water regime of the road and road reserve. Experience shows that such activities often cause slumping of stable slopes near roads.

8.2.2 Construction impacts of the highway routes Two main characteristics, the steepness of the slopes and the nature of the soils, have been used in this study to assess the potential for soil erosion along various segments of the proposed Knysna highway and its alternatives. For the purposes of this impact assessment, the highway has been divided into three sections, namely the western, central and eastern sections, and the erosion impacts for each section have been assessed for both the Proposed and the Short highway routes. The Western section of the highway begins at Groenvlei and ends where the Proposed and Short Routes meet again just west of the Eastford interchange. The Central Section runs from the Eastford Interchange to the Uniondale Interchange and is common to both of the highway routes being assessed in this EIA. The Eastern Section runs from the Uniondale interchange to the Brackenhill interchange in the case of the Proposed Route and to the proposed Springfield interchange on the existing N2 road for the Short Route. The levels of erosion hazard for the various sections of the highway are represented in figures 8.1-3. No significant erosion potential exists if the Do Nothing option is chosen as this is an existing road. The present road and associated erosion probabilities have mostly been managed efficiently to reduce erosion. This alternative has therefore been excluded from the assessment of the erosion impacts provided below. Impact 1: Very Severe Erosion Hazard Proposed Route There is a very severe erosion hazard along a portion of the Western section of the Proposed Route from Westford Bridge estate (on the western banks of the Knysna river) and just west of the intersection with the Rheenendal Road. This section of the road is particularly steep (see figure 8.4 below) and has cover sands that are particularly thick and this will create a very high risk of slope erosion and movement of sediment occurring. This erosion hazard is exacerbated along this section by the presence of lateritised and clay-rich palaeosol horizons within the cover sands. Small changes in the storm water runoff management of the terrain above or below the road can cause water to penetrate to denser layers of soil where it accumulates and creates slip-faces. Consequently, the significance of the erosion impact along this portion of the western Proposed Route is rated as VERY HIGH NEGATIVE. The application of the recommended mitigation measures outlined in section 5 of this report could reduce the significance of this impact to HIGH.



Figure 8.4: Road alignment above Westford Bridge estate. The Proposed Route passes approximately along the base of the plantation line in photo. The removal of pine trees above and below the road alignment prior to construction to make way for the new road along this section will result in increased storm water runoff and concomitant erosion such as piping and slumping. Accumulated road runoff water will also cause significant problems on slopes below the road. Short Route There are no sections of the Short Route which present a very severe erosion hazard. Significance Statement for the Construction Phase

Effect Impact Temporal

Scale Spatial Scale Severity of Impact

Risk or Likelihood

Total Score

Overall Significance

Common Central Section Without

Mitigation N/A N/A N/A N/A N/A

With Mitigation N/A N/A N/A N/A N/A

Western Section of Proposed Route Without

Mitigation Medium 2 Study Area 2 Very Severe 8 Definite 4 16 VERYHIGH -

With Mitigation Medium 2 Study Area 2 Severe 4 Definite 4 12 HIGH -

Western Section of Short Route Without

Mitigation N/A N/A N/A N/A N/A N/A

With Mitigation N/A N/A N/A N/A N/A N/A

Eastern Section of Proposed Route Without



Eastern Section of Short Route Without





Impact 2: Severe Erosion Hazard Common Central Section of the Highway Between the Concordia ridge and Uniondale road, the highway will also run through a wetland area that constitutes the source of the Salt River, to the south of the Akkerkloof Dam. In order for the road to be constructed in this area the wetland would in all probability have to be filled in during the construction phase. There is a possibility that fill material can be washed into the Salt River. The soils here are mostly cover sands of varying thickness. The danger of this action is contained in the kind of soil that will be used to fill the wetland. There is also a possibility that the wetland is the result of a perched water table, which increases the risk of slumping during wet periods. Adequate sub-soil drainage must be provided to avoid the possibility of slumping. Proposed Route (Eastern Section) For the Proposed Route the eastern section involves the construction of a long section of new undulating road through forest plantations between the Uniondale interchange and the Brackenhill interchange and toll plaza. Cover sands deposits are also thick along this section, but contrary to the more western deposits, the slopes are not as steep, and far less cutting will have to be done. (See erosion slope analysis) therefore the erosion potential is considerably lower. Short Route (Eastern Section) For the Short Route, the eastern section involves the construction of a short section of new downward sloping road through forest plantations between the Uniondale interchange and a new interchange at Springfield. The soils on this road section are the same as for the Proposed Route further north, and there is a reasonable potential for erosion of the cover sands. Slopes in this section are not as long as in other areas and erosion could be contained with sound erosion control measures (see Figure 8.3 for detail on Springfield Link). Significance Statement for the Construction Phase



Risk or Likelihood

Total Score



Mitigation Long Term 3 Study Area 2 Severe 4 Probable 3 12 HIGH -

With Mitigation Short Term 1 Localised 1 Slight 1 Unlikely 1 4 LOW -








Mitigation Medium 2 Study Area 2 Severe 4 Definite 4 12 HIGH -

With Mitigation Short term 1 Study Area 2 Moderate 2 May

Occur 2 7 LOW -


Mitigation Medium t 2 Study Area 2 Severe 4 Probable 3 12 HIGH-

With Mitigation Short term 1 Study Area 2 Moderate 2 May

Occur 2 7 LOW--



Impact 3: Moderate Erosion Hazard Common Central Section of the Highway The common central section of the highway, which is all new road, traverses the Enon conglomerates from Westford Bridge, across the Knysna River around the northern side of Knysna Heights up to White Location. The conglomerates have a moderate to high erosion potential if left unmitigated. The road cutting round the Knysna Lagoon exposes a steep high angle face of conglomerate. Although generally competent, this face is unstable during heavy rains as storm water runoff flushes out the cementing material between the clasts. Portions of this cut failed during the floods in August 2006. The situation is exacerbated by directed run-off (from hard surfaces above) and removal of vegetation above the cut. The Enon conglomerate changes in composition with distance from the northern fault boundary. Conglomerates further from the fault line are likely to be more matrix supported (have less pebbles and more sand in them) and be less stable. However, without extensive soil testing it is not possible to predict where this fault lies. The faulting is not uniform and may meander. Consequently, variations in soil characteristics should be expected along this section and soil profiling test holes during the design phase should inform the design and selection of mitigation measures. . Proposed Route (Western Section) On the eastern bank of the Knysna River where the highway crosses up to the Eastford interchange, there are Enon conglomerate soils and steep slopes (see Figure 8.5). These Enon soil banks are more stable with less erosion potential than the cover sands on the western banks. The application of erosion control methods as described previously should contain unwanted erosion along this east bank section. Consequently the significance of the erosion impacts for this section is rated moderate. Short Route (Western Section) Just east of the White Bridge there will be a new section of road constructed, where it runs up a kloof cutting through the Enon cliff. Less than 2 km of this cutting will pose a moderate erosion risk. The proximity to the lagoon and the silt content of the Enon lithologies makes it imperative to pay close attention to runoff management and the stabilisation of the cut surfaces. Erosion potential on this steep slope is severe (but lower than that for the deep cover sands on west bank of the Knysna river) during the construction phase and runoff must be carefully controlled to prevent the silt from entering the Knysna Lagoon. A clay-rich cap on top of the Enon layer on the Welbedagt plateau also has a high erosion potential, particularly in the areas where the cut will be made for the ‘Short’ route (See Figure 8.5). Significance Statement for the Construction Phase



Risk or Likelihood

Total Score



Mitigation Permanent 4 Localised 1 Severe 4 May Occur 2 11 MODERATE

- With

Mitigation Permanent 4 Localised 1 Moderate 2 Unlikely 1 8 MODERATE -


Mitigation Permanent 4 Localised 1 Severe 4 probable 3 12 HIGH -

With Permanent 4 Localised 1 Moderately 2 May 2 9 MODERATE





Risk or Likelihood

Total Score


Mitigation Severe occur - Western Section of Short Route

Without Mitigation Permanent 4 Localised 1 Severe 4 May

Occur 2 11 MODERATE -

With Mitigation Permanent 4 Localised 1 Moderately

Severe 2 Unlikely 1 8 MODERATE -







Figure 8.5: Excavation into clay horizon overlying Enon Conglomerate Impact 4: Low Erosion Hazard Short Route West of White Bridge the Short Route follows the existing N2 road so will not involve the construction of a new road. There will however be some modifications to the existing road, particularly at the sharp steep bend in the road immediately west of White bridge. Here the sharpness of the bend in the road will need to be reduced and this will involve some cutting into the northern slope. Some slumping occurred on the existing slope in the past. Care should be taken to stabilise the new cutting along the same lines as proposed for cover sands. Compared to the ‘Proposed’ route this section is significantly less prone to erosion due to the fact that the cuts already exist. Only a very short section will have to be reshaped to lessen the severity of the curve. This will allow reshaping of the cut to a less acute angle. The length of this new section is relatively short, approximately. 1km. Some slopes along a section of the proposed change are fortunately relatively flat and will only pose a very moderate threat if water management is done diligently.



Significance Statement for the Construction Phase Effect

Impact Temporal Scale Spatial Scale Severity of

Impact

Risk or Likelihood

Total Score









Mitigation Short 1 Local 1 Moderate 2 May occur 2 6 LOW -

With Mitigation Medium 2 Local 1 Slight 1 Slight 1 5 LOW -







8.2.3 Construction Impacts of the Bridges Impact 5: Impact of excavation into Enon Conglomerates The new bridge to be constructed across the Knysna River for the Proposed Route, as well as the bridge to be constructed over the Salt River, will require the excavation of Enon Conglomerate. This applies to all the bridge types being considered, as well as the viaduct for the Short Route. The Enon Conglomerate that would have to be excavated contains clay and silt. Given the erodible nature of these soils and the slopes of the approach roads there is a danger that these materials could be washed into the river systems. Mitigation Measures: The same precautionary measures as discussed in section 8.2.1 apply. Care should be taken that the excavated materials are not washed into the river systems by applying the appropriate erosion control measures. These measures should be incorporated into the Construction Environmental Management Plan (CEMP). Significance Statement for the Construction Phase



Risk or Likelihood

Total Score


Proposed Knysna Bridge Types (All) Without

Mitigation Short Term 1 Study Area 2 Moderate 2 Probable 3 8 MODERATE -


Salt River Bridge Types (All) Without





Impact 6: Importation of Fill Material In the case of the Proposed Route, the construction of the A type bridge, which is similar to the existing White Bridge, would require the use of considerable fill material to construct the road over the mud flats particularly on the western bank of the Knysna river channel. In the case of the Short Route, the widening of White Bridge and the approach road over the east bank of the river will require the use of fill material to widen the road (although some of this widening is already taking place as part of the process of upgrading the Lagoon road). In addition, there will be a need to construct a temporary traffic accommodation road over the mud flats while the viaduct is being constructed. This will require the use of additional fill material. The possibility exists that fill material imported for the construction of the bridges and widening of the roads over the mud flats could be eroded and spilled into the river systems. Most of the bridges will in all probability have approaches over wetlands, these fill areas have the potential for siltation of the wetland systems. Mitigation Measures: Construction Phase Appropriate erosion control measures should be put in place. Particular attention will have to be given to stabilise the fill areas in such a way that there is no possibility of erosion on to the river/esturary in the post construction period. These measures should be incorporated into the Construction Environmental Management Plan (CEMP). Operational Phase After the completion of the bridges, the erosion potential remains moderate due to the masses of fill material that will be contained in the embankments. Care should be taken to maintain vegetation cover and retaining walls in good repair during the operational phase. Significance Statement for the Construction Phase



Risk or Likelihood

Total Score


Proposed Bridge Type A Without

Mitigation Short Term 1 Study Area 2 Severe 4 Probable 3 1 MODERATE -

With Mitigation Short Term 1 Localised 1 Slight 2 May

occur 2 6 LOW -

Short Route (White Bridge and Viaduct) Without


With Mitigation Short Term 1 Localised 1 Slight 1 May

occur 2 5 LOW -

Construction Impacts of the Interchanges Impact 7: Moderate erosion impact of Interchanges Eastford Interchange Moderate slopes occur in the area of the proposed interchange on the Greeff farm. Clay soils overlay the Enon formation on the slopes above the river. Perhaps of greater concern is the link road proposed from the Eastford Interchange to the current N2 which requires a very deep cut into white to pink clay overlying the Enon conglomerate immediately to the north of the N2. An excavation made by a private individual into this slope above the Point is illustrated in Figure 8.3. Two years later, no natural rehabilitation has occurred. Stabilisation and rehabilitation in this horizon is difficult.



Impact 8: Low Erosion impact of Interchanges Rheenendal Interchange (Proposed Route only) To the east of the existing Rheenendal road in the vicinity of the proposed interchange there is a steep east-facing slope that should be avoided. The area is underlain by cover sands and therefore there is a very high potential for erosion. Salt River Interchange The Salt River Interchange is on a relatively level area and therefore minimal impact due to slope is envisaged. No erodible soil conditions occur in the area. Potential erosion could occur from imported fill and construction material. Cognisance should be taken of the fact that the proposed intersection would have to be over or adjacent to the Salt River and therefore the envisaged impact is similar to that of the Salt River Bridge (Para. 8.2.3) Uniondale, Springfield and Brackenhill Interchanges (R339) The Uniondale , Springfield and Brackenhill interchanges have the same erosion risk because they are all placed on cover sands and undulating topography . Some levelling may be necessary and there are wetland areas between the dunes that may be impacted. Mitigation Measures There are cover sands in the areas where the Rheenendal, Uniondale Springfield and Brackenhill interchange would be developed. Cover sands have a high erosion potential and adequate erosion control measures need to be put in place. In the event of any disturbance rehabilitation and re-vegetation should take place as soon as possible. Each disturbed site must be re-vegetated with plants similar to the vegetation type at the particular spot. The Environmental Control Officer should give guidance to the contractor regarding the method and type of vegetation replacement. Water penetration into the subsoil on this slope has the potential of causing severe slope failures and therefore early protective measures should be put in place to regulate storm water above and below the road. All of the mitigation measures discussed in section 5 should be considered. These measures should be incorporated into the Construction Environmental Management Plan (CEMP). All of the mitigation measures discussed in section 8.2.1 should be considered. These measures should be incorporated into the Construction Environmental Management Plan (CEMP). In the case of the Rheenendal interchange, avoid the steep east facing slope. For the Eastford interchange where there are Enon conglomerates overlain with clay the erosion hazard can be managed with good erosion control measures in place as outlined in section 8.2.1. The Eastford Link back to the N2 will require a carefully engineered solution. Deep cuts into the clay should be avoided. Shallow cuts will need to be stabilised with hard structures. Significance Statement for Interchanges (Construction Phase)



Risk or Likelihood

Total Score


Rheenendal Interchange Without

Mitigation Medium 2 Localised 1 Moderate 2 Probable 3 8 LOW -

With Mitigation Short Term 1 Localised 1 Moderate 1 Unlikely 1 4 LOW -

Eastford Interchange Without

Mitigation Permanent 4 Localized 1 Severe 4 May Occur 2 11 MODERATE

- With

Mitigation Permanent 4 Localized 1 Moderate 2 May Occur 2 12 MODERATE

- Salt River Interchange

Without Mitigation Short Term 1 Study Area 2 Severe 4 May

Occur 2 9 MODERATE -






Risk or Likelihood

Total Score


Uniondale Interchange Without

Mitigation Short Term 1 Localised 1 Moderate 2 May occur 2 6 LOW -


Springfield Interchange Without



Brackenhill Interchange (Propose Route Only) Without



8.2.4 Construction Impacts of the toll Plazas Impact 9: Erosion impact of Toll Plazas Due to the nature of operations of toll plazas, the sites chosen for their locations are on level ground. There is therefore only probable that erosion would take place, no matter what soil type overlays the sites. Mitigation Measures It is therefore suggested that the general erosion control precautions should be applied. In addition, care should be taken to prevent pollution of the very shallow water table at the Groenvlei Plaza site due to its close proximity to the Groenvlei Lake and Goukamma Reserve. Significance Statement for Toll Plaza Sites (Construction Phase)



Risk or Likelihood

Total Score


All Toll Plaza sites Without

Mitigation Medium 2 Localised 1 Moderate 2 Probable 3 8 MODERATE -

With Mitigation Short Term 1 Localised 1 Moderate 1 Unlikely 1 4 LOW -

Operational impacts Impact 10: Moderately Severe Erosion Hazard The erosion potential for sections of the road with deep cuttings into the cover sands will remain moderately high. These erosion risk areas are relevant to the western section of the Proposed Route only. More specifically to the west bank of the Knysna River up to just west of the Rheenendal interchange where there are deep cover sands. Mitigation measures applied during construction may become ineffective during the operational phase due to change of land use of the surrounding areas adjacent to the road (i.e. a fire may destroy the ground cover, or road runoff patterns from adjacent development may change).There are many examples of embankments failing years after construction due to such changes.



Mitigation Measures As it takes time for slopes to be rehabilitated and for vegetation to take effective root in the infertile soils typical of the Knysna area, it will be necessary to monitor the rehabilitation process for a few years after completion of construction to ensure that rehabilitation is effective. Thereafter, it will be a matter of monitoring the highway and particularly the drainage from and around the road to ensure that no erosion or slumping occurs, and maintaining the vegetation cover, retaining walls and drainage channels in good repair. If it does occur, then rapid implementation of additional rehabilitation measures will be needed. The monitoring and maintenance work will entail the following:

• Vegetation of road verges and cut faces must be inspected and maintained on a regular basis. This is particularly important on steep slopes.

• Water runoff conduits and stormwater swales must be monitored for undercutting and piping Any sign of deterioration must be attended to promptly as inadequate spillways tend to erode on the soft edges of the structures, causing undercutting and collapse.

• Any new activity such as installation of underground services should be scrutinised for possible impacts on the water regime of the road and road reserve. Experience shows that such activities often cause slumping of stable slopes near roads.

Significance Statement for Operation Phase



Risk or Likelihood

Total Score






Mitigation Permanent 4 Study Area 2 Severe 4 Probable 3 13 HIGH -

With Mitigation Permanent 4 Study Area 2 Moderate 2 Probable 3 11 MODERATE

- Western Section of Short Route

Without Mitigation N/A N/A N/A N/A N/A








Impact 11: Low Erosion Hazard Once the construction of the highway is complete and the recommended mitigation measures for the construction phase have been employed, and the rehabilitation measures have become effective, there should be little risk of further erosion for most sections and aspects of the Highway. Consequently, the erosion risks during the operation phase for almost the whole length of the highway (except for the portion of the western section of the ‘Proposed’ route mentioned above), as well as all the interchanges, bridges and toll plazas, will be low.



Mitigation Measures The mitigation measures would be the same as recommended in Impact 8.2.1 above. Significance Statement for Operation Phase



Risk or Likelihood

Total Score


All aspects of the Highway Without

Mitigation Permanent 4 Study Area 2 Moderate 2 May occur 2 10 MODERATE

- With

Mitigation Permanent 4 Localised 1 Slight 1 Unlikely 1 7 LOW -

8.2.5 Comparisons of Alternatives For the purposes of this comparison of the alternative routes, the highway has been divided into three sections, namely the western, central and eastern sections. The central section is common to both highway routes, while the western and eastern sections have different alignments and impacts. The Central Section Common to Both routes The central section runs from the Eastford to the Uniondale interchange. Most of the streams draining the central section run into wetlands and the Knysna Lagoon. Due to the position of the road in relation to the streams draining into Knysna Lagoon, erosion risk in this section should have a higher impact rating than sections that do not drain into the Knysna lagoon. Massive cut and fill operations will have to be made in some sensitive areas on the western facing slopes above the Salt River. In addition, the slopes along which the alignment is re-routed adjacent to the informal settlements show a marked tendency to slip and erode when the natural vegetation is disturbed. The erosion of cover sands to the east of Nekkies is a possibility, but the slopes are not as long and steep as the sections to the west of Knysna River. The Western Section The Proposed Route in the western section will involve the construction of a new road from Buffelsvermaak to the Eastford interchange with a new bridge over the Knysna River. The Short Route, on the other hand, will have a much shorter section of new road from White Bridge to the Eastford Interchange. The Proposed Route Firstly, massive cut and fill operations will have to be made in the most sensitive areas, specifically the western banks of the Knysna River. Large scale embankments through the Knysna River will be necessary for bridge option A (with culverts in the fill area). Apart from the loss of additional salt marsh vegetation, the additional obstruction of the flood plains will expose more surfaces to possible erosion by rain and flood water. The Short Route



The Short Route will require substantial fill at the proposed viaduct to the east of the White Bridge but the fill area over healthy salt marsh is significantly smaller than that for bridge type A associated with the Proposed Route. Erosion potential of the Enon conglomerate is moderate to high, but it is much more manageable than the cover sand slopes that will be exposed to the west of the Knysna River. The Eastern Section The Proposed Route along this section involves the construction of a new road from the Uniondale interchange to the Brackenhill interchange and toll plaza, but it will also involve the construction of a new link road from the Uniondale interchange to Springfield. By contrast, the Short Route will only have a short section of new road from the Uniondale interchange to Springfield. The Proposed Route This route will have almost the same impacts as the Short Route along this section, but in addition have the long section of road from the Uniondale interchange to Brackenhill. The streams draining the eastern section mostly drain away from the Knysna lagoon, thus making the erosion impact rating somewhat lower. There are however some small wetlands that may be impacted negatively. A combination of shorter slopes and distance from the Knysna lagoon makes the erosion impacts along this section lower than those of the Western section of the Proposed highway. Cover sand deposits along this section are also thick (as in the western section), but contrary to the more western deposits, the slopes are not as steep, and far less cutting will have to be done (see erosion slope analysis in Figure 8.3). Consequently, the potential damage from erosion is considerably lower. The terrain is undulating with a series of low coversand hummocks and small valleys containing wetlands along the drainage lines. By appearance it would seem to be old stabilised sand dunes. The concern about erosion hazards for this far eastern section are also lower than those for the western section due to the greater distance away from the Knysna estuary and the lack of any feeder rivers into the Knysna estuary. In some cases the drainage lines go into the Noetzie River and not the lagoon. The Short Route The Springfield link runs across cover sand ridges but the slopes are gentler than those to the west of Knysna River. Erosion potential for this Springfield link section compared to the Proposed Route is more or less similar but there may be a slightly smaller potential for damage to the small wetlands between the cover sand ridges. The Do Nothing Option Erosion potential along the present road alignment is lower than both the previously discussed options provided that run-off water remains properly managed (Table 8.3). Comparison of the Interchange Options



As both the Eastford and Salt River interchange sites are located in the common central section, they have no effect on the erosion impact of the two highway route alternatives. They both have moderate impacts, which can be mitigated to a Low level in the case of the Salt River interchange. This suggests that the Salt River interchange might be a slightly better option with regard to erosion potential, but there is not that much difference between them.



Comparison of the Toll Plaza Options As all the toll plazas would be located on relatively flat areas there is little if any potential erosion impact associated with them. The alternative plaza sites proposed for the two highway routes therefore make no difference to their overall erosion impact. Erosion potential is therefore not a factor that would influence the choice of toll plaza sites. Table 8.3: Summary of Erosion Impacts Issue/Impact Significance Without With Mitigation

Highway Route impacts Impact 1: Very Severe Erosion Hazard Common central section N/A N/A Western -proposed VERY HIGH - HIGH - Western -short N/A N/A Eastern -proposed N/A N/A Eastern - short N/A N/A Impact 2: Severe Erosion Hazard Common central section HIGH - LOW - Western -proposed N/A N/A Western -short N/A N/A Eastern -proposed HIGH - LOW - Eastern - short HIGH - LOW - Impact 3: Moderate Erosion Hazard Common central section MODERATE - MODERATE - Western -proposed HIGH - MODERATE - Western -short MODERATE - MODERATE - Eastern -proposed N/A N/A Eastern - short N/A N/A Impact 4: Low Erosion hazard Common central section N/A N/A Western -proposed N/A N/A Western -short LOW - LOW - Eastern -proposed N/A N/A Eastern - short N/A N/A

Bridges Impact 5: Excavation into Enon Conglomerates Proposed Knysna Bridge (all) MODERATE - LOW - Salt River Bridge (all) MODERATE - LOW - Impact 6: Importation of Fill Material Proposed Knysna Bridge Type A MODERATE - LOW - Short Route White Bridge MODERATE - LOW -

Interchanges Impact 7: Erosion impact on interchanges Rheenendal Interchange LOW - LOW - Eastford Interchange MODERATE - MODERATE - Salt River Interchange MODERATE - LOW -



Issue/Impact Significance Without With Mitigation Uniondale Interchange LOW - LOW - Springfield Interchange LOW - LOW - Brackenhill Interchange LOW - LOW -

Toll Plaza Impact 8: Erosion impact on toll plazas All Toll plazas LOW - LOW -

Operational Impacts Impact 9: Moderately Severe Erosion Hazard Common central section N/A N/A Western -proposed HIGH - MODERATE - Western -short N/A N/A Eastern -proposed N/A N/A Eastern - short N/A N/A Impact 10: Low Erosion Hazard All Aspects MODERATE - LOW - Western Section HIGH - MODERATE - 8.2.6 Conclusion and recommendations Minimise Erosion by Shortening the Highway Taking in consideration the very real possibility of massive soil erosion during construction of the N2 Highway, it makes sense to support the shortest possible route through the highly erodible cover sands. The Western Section: The Proposed Route The section of the Proposed Route to the west of Knysna River has to traverse deep deposits of cover sand, (as seen at the van Reenen Quarry) with very steep slopes presents unacceptably high erosion hazards that are difficult to mitigate. It is recommended therefore that this section be avoided if at all possible. The Short Route will allow avoidance of these deep cover sands close to the Knysna River. It is therefore recommended that the Short Route is the best alternative and should be constructed. Further, the western section of the Proposed Route should not be constructed, now or in the distant future. If this western section for the Proposed Route cannot be re-aligned to a less sensitive area, very stringent erosion control measures will have to be put in place in order to address the high erosion potential of the area. Very diligent maintenance of the cuts and the areas on either side of the road will have to be provided for the duration of the operational phase. Erosion Mitigation Measures

Due to the varying conditions along the route, each site will have to be evaluated on merit as construction progresses. Soil testing results will determine the scale of mitigation measures to be applied. As a general rule, the combination of steep slopes and cover sands should indicate red light conditions, both for construction and operational phases. It is recommended that the listed methods and precautions should serve as a minimum standard and that innovative methods should be considered as and when they become available. Understanding “erosion potential”



Erosion potential is determined by the following factors:

• Soil type • Slope gradient • Rainfall (high precipitation over short period ) • Vegetation and ground cover.

With regard to the present study the following conclusions can be made, taking the above factors in consideration

o Deep cover sands on steep slopes with poor vegetation cover invariably lead to disastrous erosion events

o Cover sands with good vegetation cover, normal precipitation on a low slope will have minimal erosion potential

o If any of the characteristics mentioned above change then the potential for erosion will change accordingly.

Preventative Treatment applicable to construction of any of the evaluated routes

• Most Importantly - Avoid removal of the natural vegetation cover. • Prevent the disturbance of the natural soil structure. Plan excavations carefully and avoid

moving heavy machinery into areas unnecessarily. • All fill material must be very well compacted and innovative use of geo-textile materials in

the retention of soil fill areas will prove to be money well spent. • Introduction of agricultural drainage methods in fill materials will serve to remove water that

could trigger slumping. • Identify perched water tables early and provide adequate drainage for these trigger points. • Create cut off drains in areas above cut slopes. Ensure that cut off drains are lined in such

a way that they do not create, rather than, alleviate problems. • Create enough storm water take off points along the route in such a way that water does

not have an opportunity to gather momentum. • Protect storm water conduit sides to avoid undercutting of hard surfaces. • Storm water ditches should contain structures that will reduce velocity of the run off. • Use of vegetated swales should be investigated in less steep areas.



8.3 Impacts on the Estuary and Aquatic environment Certain natural and anthropogenic activities, e.g. floods, and placing bridge structures in a river or estuarine bed, cause immense damage to the structure of banks and river / estuary beds, and therefore the channel in which the water flows. The physical channel structure forms the template for instream habitat, and is essential for maintaining habitat quality. Any changes in channel condition and structure would have a cumulative effect, and if sufficiently extreme, may result in a shift in population structure and possibly biotic diversity at a site. Macroinvertebrates are particularly dependent on instream habitat availability, and due to their short life-spans and localised habitats, are very vulnerable to changes in channel structure and resultant changes in instream habitat. All impacts on aquatic bodies that result in changes to habitat, flow pattern or hydrodynamics and water quality have the potential to cause changes in ecosystem structure and function, and subsequent loss of biodiversity and species richness. Estuarine ecosystems, however, are dynamic in nature meaning their ability to assimilate change is greater than other more sensitive aquatic environments i.e. small streams and wetlands. Due to the location of the changes associated with the Knysna toll highway, all the aquatic impacts are expected in the true estuarine section of the Knysna Estuary, that is, upstream of the present White (N2) Bridge. The assessment of the impacts on the estuary and aquatic environment focussed mainly on the impacts within the estuary channel. The impacts on the salt marsh vegetation on the mud flats along the banks of the Knysna river were assessed separately in the Terrestrial Ecology Assessment which is dealt with in section 8.4. All the potential aquatic impacts of the Highway are associated with the impacts of the alternative bridge options. These were assessed for both the Knysna River and one of its tributaries, the Salt River which will also be affected by the highway project. With respect to the crossings over the Knysna river, ‘Proposed’ route would involve the construction of a new bridge in the upper estuary between the existing N2 White Bridge and Red Bridge, and a new bridge across the Salt River (see Figure 5.3.1 in Specialist Volume Part 1). The ‘Short’ route would involve some widening of the existing N2 White Bridge that was built using earth embankments that transect large areas of salt marsh. While extra lanes will be accommodated, it is assumed that no extra pillars will be constructed in the river channel. The approach over the mud banks on the east bank will be widened up to the point where the viaduct will be constructed to lift the road up to the upper half of the ridge on the east bank of the Knysna River. During the construction phase of this route, a temporary traffic accommodation road will also need to be constructed across the mud banks while the viaduct is being constructed. At the top of the ridge on the east bank of the Knysna river the ‘Short’ route will join the ‘Proposed’ route just west of the Eastford Interchange and will therefore also involve the construction of a new bridge across the Salt River. In addition, if a toll plaza is built at Eastford for the ‘Short’ route, it will also be necessary to upgrade the existing Red Bridge to accommodate one-way vehicle traffic, so as to provide the residents of Rheenendal, Belvidere, Brenton Lake and Brenton-on-Sea with a non-toll alternative. For the ‘Proposed’ route, three Knysna Bridge options were assessed:

• Option A (short bridge and fill over the salt marsh): four piers in the main channel and earth fills over the salt marsh on each side of the bridge. As a mitigation strategy, allowance has been made to provide three evenly spaced 3.6m wide and 3m high box culverts under the western approach embankment to facilitate the flow of water under the embankment when the river is in flood. The size and number of culverts actually required will need to be reviewed during the detailed design stage when a full hydraulic investigation and design has been completed. Even with these culverts in place, river flow will be restricted. This option is likely to increase river depth during floods and cause upstream sedimentation similar to the sedimentation above the red bridge.



• Option B (long bridge extending over the floodplain supported by narrow piers): longer bridge that does not have earth fills but has 13 piers across the channel (No’s 8, 9 and 10 in the channel) and salt marsh (1-7 and 11-13 in the salt marsh).

• Option C (Cable Stayed bridge over the floodplain): a bridge that spans the estuary channel and floodplain except for one large support on the eastern side and narrow piers of the western side of the floodplain (similar to Option C). It is assumed that due to space constraints the large support on the eastern side will be at least partially in the river channel.

When this EIA was initiated, the aquatic team was asked to assess the impact of one other type of bridge namely a long suspension bridge with two tall suspension towers on each side of the river with no piers in the river channel or floodplain, which has been referred to in this report as Bridge Type D. The highway design engineers subsequently revealed that it would not be possible to construct such a bridge for the Proposed Route due to the curvature of the bridge on the west bank of the river. Consequently, this type of bridge was not assessed further in the EIA. However, due to the concerns about the impact of a new bridge on the river and estuary, the aquatic team did consider briefly the impact that such a suspended bridge might have on the aquatic environment should it be possible to construct such a bridge and found that it would have the least impact. There were four proposed designs for the Salt River Bridge (common to both the ‘Short’ and ‘Proposed’ routes) and these all include earth fills/embankments, with varying numbers of pillars across the narrow floodplain and even narrower channel. Due to the channel morphology and sediment characteristics of the Salt River at the bridge crossing site, it was concluded in the geomorphological assessment that the erosion and sedimentation responses to the four different bridge options would not differ significantly. This therefore suggests that the impacts identified will be the same regardless of the bridge design, therefore only one rating per impact is given for the Salt River Bridge. The ‘Short’ and ‘Proposed’ routes both include the construction of an interchange (half or full diamond) within the Salt River floodplain tributary. The impacts of this will be minimal although the rating has been included in Section 11: Comparison of Alternatives. While all impacts will result from the construction phase, the biotic impacts, and the addition of contaminants (water quality impact), will persist into the operational phase and become permanent impacts (or will persist as long as the bridges remain). These impacts are thus the same for both phases, but more significant in the operational phase so have been assessed for this phase only. The remaining three water quality related impacts are relevant to the construction phase only and are thus rated as ‘short’ in the temporal scale in the impact rating below. As the presence of the bridge is the cause of the impacts, mitigation effects for Bridge Options B and C were not taken into consideration, as the bridge design alternatives are the most effective way of mitigating the impacts. Ratings are therefore without mitigation. For Bridge Option A, however, culverts can be inserted through the embankments on the floodplain, mitigating the ‘change in available habitat’ impacts. These have therefore been rated before and after mitigation for Bridge Option A. As the impact assessment refers to the water column and intertidal regions only, no less habitat will be lost as a result of the culverts, therefore the ‘loss of habitat’ ratings are without mitigation only. The water quality impacts can be mitigated during the construction phase (‘Short’ duration) – mitigation measures have been listed, and the impacts rated before and after mitigation. The biggest threat (driver of change) to the aquatic systems affected by the proposed bridges is excessive sedimentation rates and to a lesser extent erosional processes. These would serve to alter the habitat available for the biotic components of the system, which is thus a resultant impact of the highway due to the presence of the bridge structures in the floodplain. These drivers of change are discussed below before proceeding to discuss the impacts on the biotic components.



8.3.1 Drivers of change in the Knysna Aquatic Systems as a result of the toll highway EROSION Erosion induced by the bridge structures such as the approaches and piers of the bridges hindering the normal flow will mainly affect the channel bed and floodplain areas in the immediate vicinity of these structures through turbulence caused by the structures acting as obstacles to free stream flow. These areas of influence are shown in Figures 8.4 and 8.5. This enhanced turbulence mainly prevails during flood conditions or normal fluvial discharge during ebb tide. On the stoss side of the obstacles very high turbulence prevails due to the strong stream flow of water. Fluid lift forces acting on mobile sediment particles within the stoss influence zone of the obstacle experience a substantial increase compared to the free stream as the sediment enters the stoss influence zone. This will create scouring on the upstream side of piers and bridge approaches. The area affected is relatively small (about 1m2 upstream of each pier, Figures 8.4 and 8.5) but the mobilisation of sediment has a much bigger impact on downstream areas where this sediment is deposited (see section 8.3.3). The overall effect is that the approaches and piers of the bridges will keep sediment in suspension for longer periods to be deposited in areas that would under undisturbed conditions not receive sediment or this much sediment. The significance is that sand size sediment particles stay suspended for a longer period of time and are transported beyond the normal area of deposition in areas that would normally only experience mud and clay accumulation. SEDIMENTATION Knysna Estuary Unlike the predominantly mature estuaries along the Southern Cape coast, the Knysna Estuary is immature and is therefore an unusual system in the broader coastal context. This statement requires some background on the development of estuaries. In a historical framework of thousands of years, estuaries best develop on coasts where sea level rises. In this setting of a drowning shoreline, sea water extends into river valleys where tidal mixing of sea water with fresh river water takes place. This tide-driven mixing process is a typical and fundamental process of estuaries. Gentle channel gradients compared to that of rivers and a low-energy depositional regime compared to that in the marine environment characterize estuaries. In addition, very effective mechanisms exist in estuaries to trap fine-grained sediment. As a combined result of these factors, sediment derived from both land and sea tends to accumulate in estuaries. During the rising sea level stage of estuary development, the rate of valley drowning generally exceeds the rate of sediment accumulation. As a result, channel dimensions in newly drowned estuarine river valleys are generally much larger than the dimensions needed for river floods to reach the sea. Such an estuary is in an immature state of development. Because channel dimensions of an immature estuary are so much larger than those of the feeder river, the coarse-grained fraction of river-flood sediment accumulates in the estuary. This sediment collects near the head of the estuary where flood water abruptly decelerates as it enters the deep and wide estuary. The bay-head delta system (term, Dalrymple et al., 1992) is the association of sediment bodies composed of land-derived sediment in the upper reaches of an estuary. In a similar way, sediment imported from the sea into the lower estuary by tidal action, accumulates on flood-tidal deltas that extend into the estuary from the tidal mouth. Like bay-head deltas, flood-tidal deltas grow into the estuary by lateral accretion. A variable fraction of sediment derived from the catchment basin consists of clay suspended in fresh water. Where fresh river water mixes with sea water in the middle estuary, the increased salt content causes clay particles to attract each other in a process termed flocculation. The flocs settle from suspension and accumulate in the middle estuary reaches. Once clay settles on the bed, the chemical attraction between clay particles continues and the clay expels water. In time, the clay bed becomes cohesive and highly resistant to erosion. Sand on the flood-tidal deltas of the lower estuary



generally remains unconsolidated. Little clay settles in these lower reaches, because tide-generated turbulence is too high there. Fresh water dominates in the upper reaches of the estuary so clay remains in suspension there. Suspended clay selectively passes down-estuary to the zone where fresh water mixes with sea water in the middle estuary reaches. So, a typical estuary has a sandy bed in both its upper and lower reaches, and predominantly muddy sediment in the middle reaches. Depending on sediment availability and the rate at which sea level rises, sediment accumulates on tide-reworked shoals in the estuary. In time the estuary fills with sediment as the bay-head and flood-tidal delta systems prograde towards each other and ultimately merge. At this stage of development the extent of scour by river floods determines the channel dimensions of the sediment-choked estuary. Such an estuary has reached its final stage of development and is a mature estuary. Since the end of the Flandrian transgression 6000 years ago, sea level along the Southern Cape coast has remained essentially stable, with fluctuations limited to 1 to 2m. As a result sediment filled most estuaries along this coast under the influence of a steady sediment supply, and attained a mature state of development. These mature estuaries typically accumulate marine and river-borne sediment during periods between floods and undergo cyclical scour during episodic river floods. This cyclicity operates on a time scale of about 20 to 50 years, depending on recurrence of major river floods. No change in shoreline outline is evident at all but one of the smaller streams that join the estuary. The single exception is the Salt River, which supplies a notable, but not excessive, volume of sediment to the estuary. The sediment volume supplied by the Salt River is probably small on an annual scale, but its cumulative contribution is probably substantial. To a much smaller extent the Ouplaas River supplies some sand to the Ashmead channel. The Knysna River and its tributaries provide most of the discharge of the combined catchment basin of the estuary. Surprisingly, this dominant river system appears to supply very little sediment. This observation is unexpected, but the 1936 aerial photographs match the latest satellite images especially well in the upper reaches of the estuary where the Knysna River deposits its sediment load. As a result, the conclusions, based on comparable sand body outlines, are indisputable. Since shallow water prevails in this area, the channels cannot accommodate enough sediment to modify the interpretation to allow for a much higher sediment influx. Chunnett (1965, p. 11) also arrived at the conclusion that very little sediment enters the estuary from the Knysna River. Any sediment kept in suspension in the rivers would pass through the rivers and accumulate in the estuary. Apart from the threat of increased sedimentation rates is the threat of sand accumulation over areas that would only experience clay deposition. This would result in a change of substrate type and possible loss of biodiversity. To quantify the volume of sediment that would accumulate at any point is not possible with the information available. It is, though, possible in a broader sense to predict where the sediment will accumulate. Knysna and Salt River The most likely influence the bridges will have on sedimentation in the rivers is an accumulation of sediment in the flow shadows just downstream of the bridge approaches. This will manifest as sand banks building on the floodplain on the downstream side of the bridge approaches (Figures 8.4 and 8.5). This process is at present evident on the floodplains downstream of the existing N2 Bridge (White Bridge). Here mud flats on the flood plain are systematically replaced by sand bars. These sand bars are permanent features that will persist as long as the bridges are in position. Flooding will not remove these sand bars as they are located in a flow shadow environment sheltered by the bridge approach. This effect is localised and mainly limited to no more than 100m downstream from the bridge.



8.3.2 Biological Impacts As the influence of the bridges is limited to the flow shadow zone shown in Figures 8.4 and 8.5, and a maximum distance of 100m downstream during flooding, the impact assessment was limited to the true estuarine environment of the Knysna and Salt River systems. Impacts refer to only the sub- and intertidal sections, with regions and impacts above the spring high tide mark (i.e. the mud flats and associated salt marsh vegetation) discussed in the Terrestrial Ecology Impact Assessment. As indicated in table 8.4. below, the impact of the anticipated erosion due to the presence of the bridges and resultant sedimentation was assessed for the six broad abiotic and biotic components of the aquatic environment. Within the biotic components, three biological aspects were considered when assessing the impacts, i.e. potential loss of diversity, loss of species abundance, and change in community composition – these three aspects combined are considered as essential for the maintenance of ecosystem health and functioning. Two principle impacts affecting the above aspects (in terms of plankton, submerged macrophytes and macrobenthos) were identified as being likely to result due to the presence of the bridges within the water column, i.e.:

• Loss of habitat (physical loss due to presence of bridge supports) • Change in the available habitat of the system which would be linked to changes in the

morphology due to hydrodynamic shifts (mediated by scouring and sedimentation), that is, a downstream replacement of muddy substrate with sand eroded from bridge sites.

In terms of fish, the most likely impact is a change in the availability of food due to the affect on the plankton and macrobenthos. With regard to the abiotic component that stands to be affected, namely water quality, four relevant impacts were identified as a result of the construction and operation of the bridges:

• Change in physico-chemical parameters i.e. temperature, pH, salinity, dissolved oxygen (related to construction activities)

• Increase in turbidity reducing light availability (related to construction activities and stormwater run-off)

• Addition of nutrients leading to excessive plant growth (related to construction activities) • Addition of potentially toxic contaminants (e.g. trace metals, poly-aromatic hydrocarbons &

polychlorinated biphenyls from operational use of the road) Table 8.4: List of potential issues and impacts on the estuary and aquatic environment Issue # Impacts

1 Change in physico-chemical parameters 2 Increase in turbidity 3 Addition of nutrients

1. Water Quality

4 Addition of potentially toxic contaminants 5 Loss of habitat 2. Plankton 6 Change in available habitat 7 Loss of habitat 3. Benthic microalgae 8 Change in available habitat 9 Loss of habitat 4. Submerged macrophytes 10 Change in available habitat 11 Loss of habitat 5. Macrobenthos 12 Change in available habitat

6. Fish 13 Change in availability of food



The Knysna Estuary represents one of the most important habitats for water birds along the Southern African coastline (Martin et al., 2000). Results of twelve water bird counts indicate that the majority of water birds (some 63%) were found downstream of the N2 Bridge, particularly in the Ashmead Channel (25% of the total counts) and on the mudbanks (38% of the total counts) on the Brenton side of the estuary. Only 3% of all the birds counted were recorded in the true estuarine environment above the N2 Bridge (Martin et al., 2000). The proposed developments are therefore unlikely tp have a long-term impact on the water bird community structure of the Knysna Estuary. However, during the construction phase of the bridges, some disturbance of the birds in the area is anticipated. These impacts, however, are not expected to be significant and are not considered further here. 8.3.3 Impact Rating Issue 1: Water Quality Cause and Comment Impact 1: Change in physico-chemical parameters – Dissolved oxygen in the upper estuary, during periods of low river input and in summer dropped below 4 mg L-1 in water >1 m deep. Any physical structure that impedes flow and increases residence time of water in the upper estuary could potentially result in hypoxic (reduced dissolved oxygen concentrations to a point detrimental to aquatic organisms living in the system) or anoxic (depletion of dissolved oxygen in the system) conditions. Such conditions have the potential to result in phytoplankton blooms (sudden multiplication of certain phytoplankton species), resulting in bad odours and toxicity to fauna. This is an operational impact, however, and is unlikely. Construction related impacts include the release of oxygen demanding wastewater into the estuary, and potential pH change should large volumes of unmixed cement enter the water column. The fresh water used during the construction phase and resultant discharge into the estuary is unlikely to significantly alter the salinity of the system. These impacts are unlikely for all options (after mitigation), and will persist for the short term only meaning they are of Low significance for all options. Impact 2: Increase of turbidity – turbidity has generally been low, <5 NTU, during periods of low river input with elevated Total Suspended Solid (TSS) concentrations (>200 mg L-1) during pulse events. However, the peaks are short lived and the water becomes clear shortly after these events. It is possible that the construction of bridges could lead to elevated TSS (and turbidity) through the discharge of wastewater and silt-laden water, but as in its natural state, the elevated levels are not likely to persist. Although submerged macrophyte density is low in the vicinity of the proposed bridges, elevated suspended solids could restrict light availability and potentially smother plants with fine particulate matter. This impact is likely to only last during the period of construction (short term) unless stormwater runoff from the road surface is high in particulate matter. Due to the interference with the river bed, impacts will be moderate for all options, but of a Low overall significance (after mitigation). Impact 3: Change in nutrient status – Phosphorus and nitrogen are essential nutrients for the growth of aquatic plants and algae. It is unlikely that there will be a significant increase in the load of nutrients entering the estuary as a result of highway runoff. However, vehicle emissions and roosting birds could contribute to an increase in ammonia (King County 2006). It is more likely the increase in availability of nutrients, through an increase in water residence time that may lead to an increase in biomass of these plants and algae. This impact is unlikely for all options (after mitigation), and will persist for the short term only and is therefore of Low significance for all options.

Knysna Environmental Impact Report – April 2009

Coastal & Environmental Services Knysna N2 Toll Highway EIA 136

Figure 8.4: Knysna Bridge sensitivity map, showing areas of expected scouring and deposition


Coastal & Environmental Services Knysna N2 Toll Highway EIA 137

Figure 8.5: Salt River Bridge sensitivity map, showing areas of expected scouring and deposition


Coastal & Environmental Services 138 Knysna N2 Toll Highway

Impact 4: Addition of contaminants – to date, there have been no major concerns with regards to the accumulation of toxins within the upper estuary. However, it is likely that toxic substances in urban and road runoff will accumulate in fine, cohesive sediment in calm backwaters in the vicinity of the bridge sites. The additional use of the bridge in the short option, and the crossing of the channel in the ‘Proposed’ route will be a new source of contaminants accumulating in the estuary. While there has been no measurable build-up of toxins along the length of the estuary adjacent to the current N2 where it borders the water, it is likely that contaminants will accumulate with continued use of the road. There is also the risk of the introduction of hydrocarbons into the estuary should an accident occur along this route, or over the bridges. This would be a moderate impact (after mitigation), and is a permanent risk. Due to the length of the road adjacent to the estuary at present (‘Do Nothing’ option), the impact is at a study area scale. While impacts for all options have a Moderate significance, the overall score of the ‘Do Nothing’ option (11) is higher than that of the other options (9) due to the greater likelihood of an accident occurring given the greater length of road adjacent to the estuary. Mitigation Measures Mitigation measures required relate to the control of silt and elevations in TSS and turbidity, pollution from litter and stockpile / storage sites, as well as the prevention of contaminants entering the water column. Suggested mitigation measures are:

• An Environmental Management Plan (EMP) must be developed and implemented during the construction phase that will ensure that contaminated water is not released into the Knysna Estuary and Salt River channels – this includes water contaminated with silt, hydrocarbons or any other kind of pollutants.

• An Environmental Control Officer (ECO) must be employed and take responsibility for ensuring that the EMP is adhered to – as detailed design will only take place if the project proceeds, ‘on-the-ground’ specifications are not yet available. It will thus be up to the ECO to approve the methods of installing the bridge support structures (caisson method) to ensure that as little sediment as possible is released into the water column.

• Access and use of the construction vehicles must be controlled to minimise the potential chemical / hydrocarbon spill resulting from accident and poor maintenance.

• Pillars, vertical columns and buttresses should not be placed within river channels if at all possible. If this is necessary, all precautions should be taken to avoid excessive disturbance of the bank and increased sedimentation into the river channel.

• The use of clean quarry run rock to construct the armour beds coupled with installation of Geotextile filters prior to filling and layer-works will substantially reduce the impact that the construction phase will have in altering the water column TSS and therefore the light environment. As a precautionary measure, a water quality monitoring programme should be put in place to measure the ambient turbidity. Should the turbidity during construction exceed 20% of the accepted ambient within 20m of the construction activities, then silt curtains should be erected around the applicable construction areas.

• Adequate runoff and storm water systems draining the road surface area are vital in the construction phase. This would involve the inclusion of a sump-system as part of the drainage system. In addition, the operational management plan for the development must ensure that the drainage systems are adequately designed and well maintained.

• Stockpiles must be located out of the floodplain, and must be present for as short a time as possible.

• All stockpiles must be protected from erosion, stored on flat areas where run-off will be minimised, and be surrounded by bunds.

• Storage containers must be regularly inspected so as to prevent leaks into the aquatic system

• Chemicals used for road surfacing and bridge building must be stored safely on site and surrounded by bunds.

• No stockpiling should take place within a wetland. • Littering and contamination of water sources during construction must be mitigated by

effective construction camp management.



• The construction camp and necessary ablution facilities meant for construction workers must be out of the floodplain and well maintained.

• Local people should be employed to act as litter patrols on a weekly or daily basis if necessary during the construction phase, to ensure that pollution is reduced at all times.

• Erosion control of all banks must take place so as to reduce erosion and sedimentation into river channels.

• Silt traps must be placed down slopes where vegetation stripping is taking place, so as to catch any silt which may move into the rivers.

• Silt traps and culverts should be regularly maintained and cleared so as to ensure effective drainage.

• Water diversion and erosion control structures must be capable of withstanding storm events with a probability of greater than 50% for the time of year during which construction takes place or as specified by the hydrological engineer.

• Weather forecasts from the South African Weather Bureau of up to three days in advance must be monitored on a daily basis to avoid exposing soil or building works or materials during a storm event and appropriate action must be taken in advance to protect construction works should a storm event be forecasted.

• Emergency plans must be in place in case of spillages onto road surfaces and/or into the river systems during the construction phase.

• A Disaster Management Plan should be compiled by the contractors and updated where required. This must allow for improved deployment of clean-up crews and containment booms within a period of two hours. These measures would ensure that the spill is restricted to a localized area and prevent the dispersal of the agents through flow and tides throughout the estuary.

Significance Statement for Water Quality

WITHOUT MITIGATION Impact Temporal Spatial Severity Risk SIG

Bridge A (PR) short (1) local (1) mod (2) prob (3) 7 LOW (–) Bridge B (PR) short (1) local (1) mod (2) prob (3) 7 LOW (–) Bridge C (PR) short (1) local (1) mod (2) prob (3) 7 LOW (–) Salt River short (1) local (1) mod (2) prob (3) 7 LOW (–) Short Route short (1) local (1) mod (2) prob (3) 7 LOW (–)

Phy

sico

-ch

emic

al

Do Nothing N/A Bridge A (PR) short (1) local (1) severe (4) prob (3) 9 MOD (–) Bridge B (PR) short (1) local (1) severe (4) prob (3) 9 MOD (–) Bridge C (PR) short (1) local (1) severe (4) prob (3) 9 MOD (–) Salt River short (1) local (1) severe (4) prob (3) 9 MOD (–) Short Route short (1) local (1) severe (4) prob (3) 9 MOD (–)

Turb

idity

Do Nothing N/A Bridge A (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge B (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge C (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route perm (4) local (1) slight (1) unlikely (1) 7 LOW (–)

Nut

rient

s

Do Nothing N/A Bridge A (PR) perm (4) local (1) severe (4) may (2) 11 MOD (–) Bridge B (PR) perm (4) local (1) severe (4) may (2) 11 MOD (–) Bridge C (PR) perm (4) local (1) severe (4) may (2) 11 MOD (–) Salt River perm (4) local (1) severe (4) may (2) 11 MOD (–) Short Route perm (4) local (1) severe (4) may (2) 11 MOD (–)

Wat

er Q

ualit

y

Con

tam

inan

ts

Do Nothing perm (4) study (2) severe (4) prob (3) 13 HIGH (–) PR = SANRAL Proposed Route



WITH MITIGATION

Impact Temporal Spatial Severity Risk SIG Bridge A (PR) short (1) local (1) slight (1) unlikely (1) 4 LOW (–) Bridge B (PR) short (1) local (1) slight (1) unlikely (1) 4 LOW (–) Bridge C (PR) short (1) local (1) slight (1) unlikely (1) 4 LOW (–) Salt River short (1) local (1) slight (1) unlikely (1) 4 LOW (–) Short Route short (1) local (1) slight (1) unlikely (1) 4 LOW (–)

Phy

sico

-ch

emic

al

Do Nothing N/A Bridge A (PR) short (1) local (1) mod (2) prob (3) 7 LOW (–) Bridge B (PR) short (1) local (1) mod (2) prob (3) 7 LOW (–) Bridge C (PR) short (1) local (1) mod (2) prob (3) 7 LOW (–) Salt River short (1) local (1) mod (2) prob (3) 7 LOW (–) Short Route short (1) local (1) mod (2) prob (3) 7 LOW (–)

Turb

idity

Do Nothing N/A Bridge A (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge B (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge C (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route perm (4) local (1) slight (1) unlikely (1) 7 LOW (–)

Nut

rient

s

Do Nothing N/A Bridge A (PR) perm (4) local (1) mod (2) may (2) 9 MOD (–) Bridge B (PR) perm (4) local (1) mod (2) may (2) 9 MOD (–) Bridge C (PR) perm (4) local (1) mod (2) may (2) 9 MOD (–) Salt River perm (4) local (1) mod (2) may (2) 9 MOD (–) Short Route perm (4) local (1) mod (2) may (2) 9 MOD (–)

Wat

er Q

ualit

y

Con

tam

inan

ts

Do Nothing perm (4) study (2) mod (2) prob (3) 11 MOD (–) PR = SANRAL Proposed Route Issue 2: Plankton (phyto- and zooplankton) Cause and Comment Impact 1: Loss of habitat – The construction of a bridge, supported by cement pillars in the estuary channel, represents a local but permanent loss of water-column habitat. Impact 2: Change in available habitat type – Phytoplankton occur in the water-column throughout the estuary, which extends to areas of salt marsh during spring high tides. Bridge Option A, unlike options B and C, includes large embankments extending over the salt marshes on both sides of the estuary channel, and will result in substantial scour during periods of high flow. This will cause a re-working of sediment and a reduction in light availability in the flow shadow of the bridge, altering the habitat type available to phytoplankton and zooplankton in the water column. If culverts are installed, this will lessen the scour at the main channel edge embankment, but result in deposition of sediment on the salt marsh altering the habitat available to phytoplankton at spring high tide. The impact as a result of the suspended sediment in the main estuary channel, however, will be less significant. Mitigation Measures As the presence of the bridge supports in the water column are the cause of the impacts, mitigation effects for Bridge Options B and C were not taken into consideration, as the bridge design alternatives are the most effective way of mitigating the impacts. Ratings are therefore without mitigation. For Bridge Option A, however, culverts can be inserted through the embankment on the floodplain, mitigating the ‘change in available habitat’ impacts. These have therefore been rated before and after mitigation for Bridge Option A. As the impact assessment refers to the water column and intertidal regions only, no less habitat will be lost as a result of the culverts, therefore the ‘loss of habitat’ ratings are without mitigation only.



Significance Statement for Plankton


Bridge A (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge B (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge C (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–)

Loss

of

habi

tat

Do Nothing N/A Bridge A (PR) perm (4) local (1) mod (2) definite (4) 10 MOD (–) Bridge B (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge C (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–) P

hyto

- and

zoo

plan

kton

Cha

nge

in

habi

tat

avai

labi

lity

Do Nothing N/A WITH MITIGATION

Change in habitat availability

Bridge A (PR) perm (4) local (1) slight (1) definite (4) 11 MOD (–)

PR = SANRAL Proposed Route Issue 3: Benthic microalgae Cause and Comment Impact 1: Loss of habitat – Benthic microalgae colonise almost all wet sediments and are particularly productive in stable environments where the deposition of fines (sediment and organic material) occur. As a result, the biomass of benthic microalgae is particularly high in the calmer middle reaches of estuaries and in exposed sediment in salt marshes. All three bridge options have concrete pillars in the estuary channel and salt marsh, which represents a local but definite loss of habitat for benthic microalgae. Bridge Option A, unlike options B and C, has large embankment extending across the salt marshes on both sides of the estuary. Even if culverts are inserted, the available benthic habitat is replaced by concrete, resulting in the permanent loss of a large area of salt marsh (a few hectares) and the loss of productive habitat for benthic microalgae. The resultant impact is of HIGH significance. Impact 2: Change in available habitat type – The construction of large embankment in option type A represents a loss of habitat but the construction of concrete pillars represents a permanent but local change of habitat type from soft, cohesive sediment suitable for epipelic microalgae to a hard substrate suitable for the colonisation of epilithic microalgae. Sand eroded and deposited downstream will replace the favoured softer sediment. Culverts will result in deposition on the salt marsh and an alteration of habitat available to benthic microalgae in this region. The culverts, however, will reduce scour and deposition in the main channel and intertidal zone, lessening the significance of the impacts. Mitigation Measures As the presence of the bridge supports in the water column are the cause of the impacts, mitigation effects for Bridge Options B and C were not taken into consideration, as the bridge design alternatives are the most effective way of mitigating the impacts. Ratings are therefore without mitigation. For Bridge Option A, however, culverts can be inserted through the embankment on the floodplain, mitigating the ‘change in available habitat’ impacts. These have therefore been rated before and after mitigation for Bridge Option A. As the impact assessment refers to the water column and intertidal regions only, no less habitat will be lost as a result of the culverts, therefore the ‘loss of habitat’ ratings are without mitigation only.



Significance Statement for Benthic microalgae


Bridge A (PR) perm (4) study (2) mod (2) definite (4) 12 HIGH (–) Bridge B (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge C (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–)

Loss

of

habi

tat

Do Nothing N/A Bridge A (PR) perm (4) local (1) mod (2) definite (4) 10 MOD (–) Bridge B (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge C (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–)

Ben

thic

mic

roal

gae

Cha

nge

in

habi

tat

avai

labi

lity




PR = SANRAL Proposed Route Issue 4: Submerged macrophytes Cause and Comment Impact 1: Loss of habitat – There are some submerged macrophytes in the vicinity of the proposed bridge (Zostera capensis is visible in the intertidal zone at the crossing point of the proposed bridge – Plate 3-1), dominated by eelgrass (Zostera capensis). The construction of the concrete pillars will represent a permanent loss of available habitat for these submerged macrophytes. In addition, there could be a short term (construction phase) increase in suspended solids in the water-column, limiting light availability and potentially smothering plants with fine particulate matter. The area covered by Z. capensis in the Knysna Estuary, based on a 1942 aerial photograph, was estimated to be 68.8 ha, and this decreased slightly to 65.9 ha by 2007 (Figures 5.3-18 in Specialist Volume Part 1) (Adams & Bornman, 2008). The permanent loss of Z. capensis from the intertidal zone where the proposed bridge crosses, estimated to be ~10 m2 based on a 30% surface cover, represents a small (<0.02 %) loss from the estuary. There are no submerged macrophyte beds that will be affected by the upgrading of White Bridge, therefore this impact does not apply to the ‘Short’ route. Impact 2: Change in available habitat type – All three bridge options have concrete pillars in the estuary channel, which represents a local but definite change of habitat for submerged macrophytes from soft sediment suitable for taxa such as eelgrass to a hard structure suitable for attached macrophytes (e.g. Ulva sp., Codium sp. etc.). Sediment (sand) eroded from the support structures (most significantly for Option A) will result in a change of available habitat in the estuary channel and on the intertidal portion of the floodplain where macrophytes are present. Effects on the floodplain will be most significant for Option A, as a result of sediment scoured from the embankment and deposited through the culverts. A lack of culverts would result in additional scouring and further deposition in the main channel, with associated negative effects. There are no submerged macrophyte beds that will be affected by the upgrading of White Bridge, therefore this impact does not apply to the ‘Short’ route. Mitigation Measures As the presence of the bridge supports in the water column are the cause of the impacts, mitigation effects for Bridge Options B and C were not taken into consideration, as the bridge design alternatives are the most effective way of mitigating the impacts. Ratings are therefore without mitigation. For Bridge Option A, however, culverts can be inserted through the embankment on the floodplain, mitigating the ‘change in available habitat’ impacts. These have therefore been rated before and after mitigation for Bridge Option A. As the impact assessment refers to the water



column and intertidal regions only, no less habitat will be lost as a result of the culverts, therefore the ‘loss of habitat’ ratings are without mitigation only. Significance Statement for submerged macrophytes


Bridge A (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge B (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge C (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route N/A

Loss

of

habi

tat

Do Nothing N/A Bridge A (PR) perm (4) local (1) mod (2) definite (4) 10 MOD (–) Bridge B (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Bridge C (PR) perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route N/A S

ubm

erge

d m

acro

phyt

es

Cha

nge

in

habi

tat

avai

labi

lity




PR = SANRAL Proposed Route Issue 5: Macrobenthos Cause and Comment Impact 1: Loss of habitat – The construction of the bridge, supported by concrete pillars in the estuary channel represents a permanent loss of soft substrate (muddy sediment) available to macrobenthos (loss likely to be ~10m2). Impact 2: Change in available habitat type – The macrocrustacea community structure is strongly linked to substrate type and availability. The presence of the concrete pillars will result in scouring and deposition which translates into a shift in the habitat availability for selected macrocrustacea. For example, should muddy substrate be replaced by sandy substrate, the mud prawn will be replaced by the sand prawn reflecting specific habitat requirements of the different species. This change will be most prevalent in the estuary channel, and will occur to a lesser degree on the floodplain in times of high flow. The impact of the change in available habitat in the channel will be most significant for Bridge Option A as a result of scouring around the embankment over the floodplain and deposition in the main channel. While culverts will result in deposition on the floodplain impacting on the habitat available to macrobenthos in this region, an absence of culverts would lead to severe scouring along the length of the embankment and additional deposition in the main channel, resulting in an impact of HIGH significance. Mitigation Measures As the presence of the bridge supports in the water column are the cause of the impacts, mitigation effects for Bridge Options B and C were not taken into consideration, as the bridge design alternatives are the most effective way of mitigating the impacts. Ratings are therefore without mitigation. For Bridge Option A, however, culverts can be inserted through the embankment on the floodplain, mitigating the ‘change in available habitat’ impacts. These have therefore been rated before and after mitigation for Bridge Option A. As the impact assessment refers to the water column and intertidal regions only, no less habitat will be lost as a result of the culverts, therefore the ‘loss of habitat’ ratings are without mitigation only.



Significance Statement for Macrobenthos WITHOUT MITIGATION

Impact Temporal Spatial Severity Risk SIG Bridge A (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge B (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge C (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–)

Loss

of

habi

tat

Do Nothing N/A Bridge A (PR) perm (4) local (1) Severe(4) definite (4) 13 HIGH (–) Bridge B (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge C (PR) perm (4) local (1) mod (2) definite (4) 11 MOD (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–)

Mac

robe

ntho

s

Cha

nge

in

habi

tat

avai

labi

lity



Bridge A (PR) perm (4) local (1) mod (2) definite (4) 12 MOD (–)

PR = SANRAL Proposed Route Issue 6: Fish Cause and Comment Impact 1: Food availability – the potential shift in the macrocrustacean community structure associated with the presence of the concrete pillars, embankment and resultant scouring and deposition will be associated with a localised change in the fish community structure reflecting the change in the food availability for selected fish species. Mitigation Measures As the presence of the bridge supports in the water column are the cause of the impacts, mitigation effects for Bridge Options B and C were not taken into consideration, as the bridge design alternatives are the most effective way of mitigating the impacts. Ratings are therefore without mitigation. For Bridge Option A, however, culverts can be inserted through the embankment on the floodplain, mitigating the ‘change in available habitat’ impacts on the macrobenthos and zooplankton i.e. the diet of the fish. ‘Food availability’ impacts have therefore been rated before and after mitigation for Bridge Option A. Significance Statement for Fish


Bridge A (PR) perm (4) local (1) severe (4) definite (4) 13 HIGH (–) Bridge B (PR) perm (4) local (1) slight (1) definite (4) 10 MOD (–) Bridge C (PR) perm (4) local (1) mod (2) definite (4) 11 MOD (–) Salt River perm (4) local (1) slight (1) unlikely (1) 7 LOW (–) Short Route short (1) local (1) slight (1) definite (4) 7 LOW (–)

Fish

Food

av

aila

bilit

y


Food availability Bridge A (PR) perm (4) local (1) mod (2) definite (4) 11 MOD (–) PR = SANRAL Proposed Route 8.3.4 Comparison of Route Alternatives The predicted impacts of the different routes are compared in Table 8.5. It can be seen that the least negative impacts are associated with the ‘Do Nothing’ option (only one HIGH impact – the water quality: toxic contaminant effects and risk of the continued road use along the estuary between Knysna and White Bridge). All impacts of the ‘Short’ route have been rated as LOW, with the exception of the water quality: toxic contaminant effects and risk which was rated as a MEDIUM impact (a higher impact rating score than for the ‘Do Nothing’ option, but still in the



MODERATE range). The ‘Proposed’ route has the most significant negative impacts, seven MODERATE impacts at least. All the Salt River Bridge and Salt River interchange impacts, common to both the ‘Short’ and ‘Proposed’ routes, have been rated as LOW, with the exception of the MODERATE water quality: toxic contaminant effects and risk in each case. While the ‘Do Nothing’ option has the least negative associated impacts, this is to be expected given the lack of construction impacts. It is understood, however, that the current traffic and road capacity trends will not be sustainable into the future, hence the MODERATE impact of the continued use of the estuary-edge road (assuming a Disaster Management Plan is / would be developed). This impact has not been rated as HIGH due to the lack of evidence of an accumulation of toxins from road run-off and use to date, but this effect is likely to increase with continued and the predicted additional road use in the future. The ‘Short’ route has less MODERATE impacts than the ‘Proposed’ route, if however the ‘Short’ route proves to be a temporary solution, the impacts of the ‘SANRAL Proposed Route’ could be realised over the long term if an additional bridge was developed for the highway in the future. If the ‘Proposed’ route is the option selected, White Bridge will not need to be widened, the viaduct and temporary road over the mudflats will not be required, and Red Bridge will not need to be upgraded, meaning these impacts will be avoided. The area affected by the viaduct area has already been altered by the fill embankment of the current N2 road, and is generally more affected by spring high tides than periods of high discharge as the channel is very wide, however if construction of an additional road can be avoided this would be beneficial to the salt marsh that would be affected, and the salt marsh conservation targets of the Knysna Estuary. Table 8.5: Comparison of impacts (after mitigation for Bridge A Impact 5, and Water quality impacts; all impacts are negative)

Issues and Impacts

Water quality Plankton Benthic microalgae

Submerged macrophytes

Macro benthos Fish Option

1 2 3 4 5 6 5 6 5 6 5 6 7 Bridge A (PR)

LOW -

LOW -

LOW -

MOD -

MOD -

MOD -

HIGH -

MOD -

MOD -

MOD -

MOD -

HIGH -

HIGH -

Bridge B (PR)

LOW -

LOW -

LOW -

MOD -

MOD -

LOW -

MOD -

LOW -

MOD -

LOW -

MOD -

MOD -

MOD -

Bridge C (PR)

LOW -

LOW -

LOW -

MOD -

MOD -

LOW -

MOD -

LOW -

MOD -

LOW -

MOD -

MOD -

MOD -

Bridge D (PR)

LOW -

LOW -

LOW -

MOD -

LOW - LOW LOW

- LOW

- LOW

- LOW

- LOW

- LOW

- LOW

- Salt LOW

- LOW

- LOW

- MOD

- LOW

- LOW LOW -

LOW -

LOW -

LOW -

LOW -

LOW -

LOW -

Short Route

LOW -

LOW -

LOW -

MOD -

LOW -

LOW -

LOW -

LOW - N/A N/A LOW

- LOW

- LOW

- Do Nothing N/A N/A N/A HIGH

- N/A N/A N/A N/A N/A N/A N/A N/A N/A Inter change

LOW -

LOW -

LOW -

MOD -

LOW -

LOW -

LOW -

LOW -

LOW -

LOW -

LOW -

LOW -

LOW -

PR = SANRAL Proposed Route; 1 = Physico-chemical, 2 = turbidity, 3 = nutrients, 4 = contaminants, 5 = loss of habitat, 6 = change of habitat availability, 7 = food availability The low sediment yield of the Knysna River, current state of the catchment and potential for erosion due to the route alignment is key to the impacts experienced downstream. The main substrate litho types occurring in the area are quartzitic sandstone of the Table Mountain Group, sandstone and conglomerate of the Enon Formation and poorly to unconsolidated Quaternary aeolian sand. Of these lithologic types, the Quaternary aeolian sand is most prone to erosion. Meteoric water leached out almost all detrital skeletal CaCO3 originally present in the older aeolian sand deposits north and east of Knysna. The remaining lime-depleted quartz sand is poorly consolidated and prone to erosion. The younger aeolian sand to the South and Southwest of the



estuary contains CaCO3, but dune rock outcrops are rare near the estuary. Reddering and Esterhuysen (1984, 1987) point out that mud most commonly occurs near the Mesozoic Enon Formation deposits, which are the probable source. The mud-yield potential of the catchment basin is low; most rock types produce quartz sand. The conglomerate component of the Mesozoic deposits resists erosion very well and commonly outcrops in near-vertical cliffs. Nearly all the route possibilities presented as the new N2 Toll Road or its alternatives are in areas where the geology map indicates the least consolidated rock types to be present. Only the northern most parts of the route that is in forested areas in the northern sector of the catchment basin lie on erosion-resistant Table Mountain quartzite. The aeolian sands in particular occur along the watersheds near the edge of the estuary and it is exactly here where most of the route alternatives have been proposed. Superimposition of high sediment-yield rock types and areas of the N2 Toll Highway development is unfortunate and could result in considerable erosion risk. Field observations show that vegetation very effectively covers almost all outcrops in the area, preventing soil erosion and trapping any sediment that may have been liberated.. The high perennial rainfall (mean, 922mm; Grindley, 1985) in the Knysna area ensures that this vegetation cover maintains itself throughout the year. However, the erosion study indicates that the construction of the highway could cause considerable erosion if not properly managed. The developers and authorities must be aware of this and make every effort to keep the period for the exposure of the unconsolidated sand as short as possible, to manage the sites effectively during construction and to re-establish vegetation immediately on completion of work. Bridge Design Alternatives – ‘Proposed’ Route While the ‘Proposed’ route has more significant (MODERATE) impacts than the ‘Short’ or ‘Do Nothing’ options, it is possible that the ‘Proposed’ route and a new bridge across the Knysna River will be required in time. Therefore, through the selection of the ‘Proposed’ route, the impacts of the ‘Short’ route (although generally LOW) will ultimately be avoided. This then calls for a comparison of the various bridge options of the ‘Proposed’ route. Discounting the impacts of Option D (discussed later), Table 8.6 shows the impacts of the three Bridge Options A, B and C that differ, that is, those that that are the same for all three (either MODERATE or LOW, see Table 8.5) have been removed to allow for an easier comparison. Bridge Option A is a short bridge with only four pillars in the river, but an approach fill over the wetlands in the floodplain on each side of the bridge. Allowance has been made to provide three evenly spaced 3.6m wide and 3m high box culverts under the western approach embankment to facilitate the flow of water under the embankment when the river is in flood. Even with these culverts in place, river flow will be restricted and this design will result in scouring and sediment remobilisation at the fill edges and at the piers in the stream channel, with resultant floodplain and river channel sedimentation. This additional sedimentation (relative to options B and C) will result in more significant biotic impacts (after mitigation) – the change in available habitat type (sandy sediments replacing the muddy substrate) will be of MODERATE impact to plankton and submerged macrophytes, while this and the loss of habitat will be of HIGH significance to benthic microalgae. This is therefore the least preferable bridge option. Bridge Option B (a longer bridge right across the floodplain which has 13 piers, three of which are in the river channel, and does not block the river flow with fill embankments over the wetland) would result in much less erosion and resultant sedimentation and negative impacts on the floodplain, but still will cause scouring and sediment remobilisation at the three piers in the stream channel. The small diameter of the individual piers will assist to minimise this effect. The result will be less significant impacts on the plankton, submerged macrophytes, and benthic microalgal components (Table 8.6) of the aquatic systems in the affected area (generally limited to within 100m of the bridge site). From a geomorphological, and (as this determined the biotic impacts)



therefore a biological point of view, it is suggested that this design would have the lowest negative influence on the biology of the system (discounting Option D). The impacts of Bridge Option C (a long bridge suspended on the eastern side by a large pillar partially in the river channel, and a series of pillars on the western side of the floodplain similar to Option B) were rated as the same as that of Option B in terms of significance. The severity of the impact on macrobenthos due to the change in available habitat, however, was rated as ‘moderate’ for Option C and ‘slight’ for Option B (although both were of MODERATE overall significance – see Section 5.4.3.5 of Specialist Volume Part 1. This was due to the larger diameter of the pillar on the eastern bank and the higher turbulence created, with the net effect that it would have a greater negative impact on scouring and remobilisation and resultant deposition of sediment than Option B. As stated, however, the impacts on the biology of the system were rated as the same in terms of overall significance (Table 8.6). Table 8.6: Impacts of ‘Proposed’ route bridge options, discounting those that are the same for all options

Issues and Impacts

Water quality Plankton Benthic microalgae

Submerged macrophytes

Macro benthos Fish Option

1 2 3 4 1 2 1 2 1 2 1 2 1 Bridge A (PR) MOD

- HIGH

- MOD

- MOD -

Bridge B (PR) LOW

- MOD

- LOW

- LOW -

Bridge C (PR) LOW

- MOD

- LOW

- LOW -

PR = SANRAL Proposed Route; 1 = Physico-chemical, 2 = turbidity, 3 = nutrients, 4 = contaminants, 5 = loss of habitat, 6 = change of habitat type, 7 = food availability

All the aquatic impacts of Bridge Option D (a long suspension bridge with two tall suspension towers on each side of the river with no piers in the river channel or floodplain) impacts were rated as LOW, with the exception of one MODERATE impact – the water quality: toxic contaminant effects and risk of crossing the Knysna Estuary (Table 8.5). In terms the least significant impacts, this bridge is therefore the most favourable. However given the low and moderate significance of the impacts of the Option B and C bridges (six LOW and seven MODERATE impacts), the high cost of Bridge Option D will need to be weighed up against the reduction of six impacts from MODERATE to LOW. Were there numerous HIGH impacts associated with Options B and C, it would be recommended that a bridge design with less significant impacts (i.e., Option D) be considered. The impacts of the bridge over the Salt River also need to be taken into consideration when deciding on whether or not to proceed with the Toll Highway. It was felt that due to the narrow confined nature of the floodplain and channel, the shallow water depth and limited habitat availability, the impacts of the four different bridge designs would not differ, and were all LOW with the exception of one MODERATE impact – the water quality: toxic contaminant effects of crossing the Salt River (Table 8.5). Pillars in the river channel, however, should be avoided at all costs. Impacts of Flooding The impact of flood events on the biology of the system is likely to remain unaltered from the present state. The inflow of freshwater will temporarily result in the collapse of the estuarine community upstream of the N2 Bridge, that is, in the true estuarine component of the system. The community will, however, become re-established once the amount of freshwater flowing into the system decreases. Although the flood events will change the hydrodynamics and channel morphology, it is unlikely to result in a loss of species. Rather, the present state distribution patterns are likely to be altered at a local scale. The impacts of this alteration of available habitat as a result of increased scouring under flood flow have been incorporated into the impact assessment, as impacts are likely to be minimal under normal stream flow.



8.4 Impacts on the Terrestrial Ecology Twelve potential impacts on the terrestrial ecology have been identified. In each case the impact table indicates the extent to which this impact applies to the various sections of the Knysna Highway as well as the interchanges, bridges and toll plazas. 8.4.1 Impact 1: Loss of forest Cause and Comment Construction of the road will lead to some direct loss of forest habitat in the footprint of the proposed road and Short Route. This will lead to localised or more extensive reduction in the overall extent of forest habitat in the study area. Where these habitats are already stressed due to degradation and transformation, the loss may lead to increased vulnerability (susceptibility to future damage) of the habitat. The overall effect of habitat loss may be increased by secondary impacts that alter the nature of habitats adjacent to the road. The distance of this secondary effect is controversial, but biological changes have been observed up to 150 m from road edges (Hansen & Clevenger 2005, Watkins et al. 2003), for example, invasion by alien plants. The main area where the road will impact on forests is adjacent to Concordia, where the road reserve directly affects an approximately 2 km linear section adjacent to the forest. It is estimated that a total of 5 ha of forest will be lost along this section along with 3 ha of scrub woodland along the forest margins. There are two other patches of forest within 200 m of the road reserve towards the eastern end of the alignment, but these will not be directly affected by the road, although they may be impacted by secondary impacts. The mitigation measures provided aim to minimize impacts, including secondary impacts, which could occur over and above the direct construction impacts. These mitigation measures would reduce the scale of the impact from being potentially regional to more localized. Mitigation Measures

• During construction, ensure that impacts are contained to as small an areas as possible. • Minimise and restrict clearing to the area required for road construction purposes only and

limit disturbance to adjacent undisturbed natural forest. • Re-vegetation of disturbed areas must be undertaken with site indigenous species. This

can provide a buffer to protect remaining indigenous vegetation from invasion by weeds and alien invader plants. The identification of which species are suitable and for which propagules are available from commercial sources needs to be established. A local nursery may need to be established to provide suitable plant material for rehabilitation purposes.

• Protect habitat through implementation of erosion and sediment control measures, including effective storm-water management.

• Ongoing monitoring and maintenance of re-vegetation works should be undertaken following construction of the road.

• Appropriate locating of stockpiles, site offices and infrastructure should be undertaken to limit damage to sensitive forest vegetation. These should not be located within forest that will not be directly lost to construction. Stockpiles, site offices and infrastructure should be located within the road reserve and preferably away from steep slopes overlooking forest.

• Implement a weed control plan to avoid the establishment and spread of weeds with the long-term measurable outcome the complete absence of alien plants in the road reserve or adjacent areas.



Significance Statement Effect


Impact

Risk or Likelihood

Total Score


BOTH ROUTES - CENTRAL SECTION Without

Mitigation Permanent 4 Study area 2 Moderate 2 Definite 4 12 HIGH -

With Mitigation Permanent 4 Localised 1 Moderate 2 Definite 4 11 MODERATE

- 8.4.2 Impact 2: Loss of fynbos Cause and Comment Construction of the road will lead to some direct loss of fynbos habitat in the footprint of the proposed road. This will lead to localised loss of fynbos patches that will result in more extensive reduction in the overall extent of fynbos along the alignment. Due to the high conservation status of fynbos in the study area, this impact has, potentially, regional to global consequences. The two types of fynbos that occur along the alignment are Garden Route Shale Fynbos and Knysna Sand Fynbos. Both of these vegetation types are classified as Endangered (see Table 6.4) and Knysna Sand Fynbos is on the verge of becoming Critically Endangered. Due to the global biogeographical significance of the Fynbos Biome, any further loss of fynbos is therefore potentially serious and of national (or even global) significance. The main area where the road will impact on Knysna Sand Fynbos is on the slopes overlooking White Bridge (Short Route only) and the main areas where Garden Route Shale Fynbos will be affected are between the Goukamma and Knysna Rivers (Proposed Route only). For the Short Route, a patch of Knysna Sand Fynbos will be severely affected by this route option, splitting it in half and traversing the most sensitive component of it. Construction of the Eastford Interchange will lead to some direct loss of a small remnant patch of Garden Route Shale Fynbos. This vegetation type is classified as Endangered (see Table 6.4). Construction of the Rheenendal Interchange will lead to some direct loss of some Knysna Sand Fynbos, a vegetation type classified as Endangered (see Table 6.4). The impacts associated with construction of the Rheenendal Interchange apply to the Proposed Route only, because the Short Route would not include construction of this section of road. In each of these cases, the overall effect of habitat loss may be increased by secondary impacts that alter the nature of habitats adjacent to the road. The distance of this secondary effect is controversial, but biological changes have been observed up to 150 m from road edges (Hansen & Clevenger 2005, Watkins et al. 2003), for example, invasion by alien plants. The mitigation measures provided aim to minimize impacts, including secondary impacts, which could occur beyond the direct construction impacts. The mitigation measures are aimed primarily at reducing the impact to the footprint of the development only and reducing the likelihood of impacts spreading beyond this immediate footprint. These mitigation measures would reduce the scale of the impact from being potentially national to more localized (if loss of fynbos can be minimized). Mitigation Measures

• Select the route option that has the least potential direct impacts on fynbos. • During construction, ensure that impacts are contained to as small an areas as possible.

Any remaining patches of fynbos must be protected, if they are not within the direct footprint of the proposed construction.

• Minimise and restrict clearing to the area required for road construction purposes only and limit disturbance to adjacent fynbos.



• Sensitive areas adjacent to the road must be demarcated and no construction activities or impacts must be permitted to occur across these demarcations.

• Independent monitoring of construction impacts must take place to ensure that no areas of fynbos outside of the construction zone are affected by construction.

• Re-vegetation of disturbed areas must be undertaken with site indigenous species. This can provide a buffer to protect indigenous vegetation from invasion by weeds. The identification of which species are suitable and for which propagules are available from commercial sources needs to be established. A local nursery may need to be established to provide suitable plant material or revegetation method for re-habilitation purposes.

• Protect habitat through implementation of erosion and sediment control measures, including storm-water management.

• Ongoing monitoring and maintenance of re-vegetation works should be undertaken following construction of road.

• Appropriate locating of stockpiles, site offices and infrastructure should be undertaken to limit damage to sensitive vegetation. Stockpiles, site offices and infrastructure should be located within the road reserve, but should not be located within any remaining areas of fynbos, even if these occur within the road reserve. Stockpiles, site offices and associated infrastructure may be located in areas outside the road reserve, if these do not contain natural vegetation, but should be at least 200 m away from any remaining patches of fynbos.

• Implement a weed control plan to avoid establishment and spread of weeds with the long-term measurable outcome the complete absence of alien plants in the road reserve or beyond.

Note that none of these mitigation measures will decrease the spatial scale or the severity of the impact of the Short Route, since it passes through the centre of a patch of Knysna Sandstone Fynbos. Significance Statement



Risk or Likelihood

Total Score


PROPOSED ROUTE – WESTERN SECTION Without

Mitigation Permanent 4 National 3 Severe 4 Definite 4 15 HIGH-

With Mitigation Permanent 4 National 3 Moderate 2 Definite 4 13 HIGH-

SHORT ROUTE – WESTERN SECTION Without

Mitigation Permanent 4 National 3 Very severe 8 Definite 4 19 VERY HIGH-

With Mitigation Permanent 4 National 3 Very severe 8 Definite 4 19 VERY HIGH-

RHEENENDAL INTERCHANGE ONLY Without

Mitigation Permanent 4 Localised 1 Moderate 2 Definite 4 11 MODERATE -

With Mitigation Permanent 4 Localised 1 Slight 1 Definite 4 10 MODERATE

- EASTFORD INTERCHANGE ONLY

Without Mitigation Permanent 4 Localised 1 Moderate 2 Definite 4 11 MODERATE

- With

Mitigation Permanent 4 Localised 1 Slight 1 Definite 4 10 MODERATE -

EASTFORD TOLL PLAZA Without

Mitigation Permanent 4 Localised 1 Moderate 2 May occur 2 9 MODERATE

- With

Mitigation Permanent 4 Localised 1 Slight 1 May occur 2 8 MODERATE

-



8.4.3 Impact 3: Loss of coastal thicket Cause and Comment Construction of the road will lead to some direct loss of coastal thicket habitat in the footprint of the proposed road. This will lead to localised loss of coastal thicket habitat. Where these habitats are already stressed due to degradation and transformation, the loss may lead to increased vulnerability (susceptibility to future damage) of the habitat. For the central section of the highway (which is common to both routes), the main area where the road will impact on coastal thickets is on the margins of the Salt River estuary crossing, where the road reserve directly affects approximately 2 ha of coastal thicket. It is assumed that this entire section will be lost. On the western section of the Proposed Route, there is a patch of coastal thicket within 200 m of the road reserve on the eastern bank of the Knysna River crossing, but these will not be directly affected by the road to any great extent, although they may be impacted by secondary impacts. On the western section of the Short Route, there are remnant patches of coastal thicket on the eastern bank of the Knysna River crossing, but these are small and fragmented by existing infrastructure.. These patches will be further fragmented by the Short Route highway. Construction of the bridges will lead to some direct loss of coastal thicket habitat on either bank of the Knysna and Salt rivers. The potential impact on thicket will be the same for all proposed bridge construction options. Construction of the Salt River Interchange will lead to some direct loss of fragments of coastal thicket habitat on the banks of the Salt River where the road crosses. This will lead to localised reduction in the overall extent of coastal thicket along the alignment. The overall effect of habitat loss may be increased by secondary impacts that alter the nature of habitats adjacent to the road. The distance of this secondary effect is controversial, but biological changes have been observed up to 150 m from road edges (Hansen & Clevenger 2005, Watkins et al. 2003), for example, invasion by alien plants. The mitigation measures provided aim to minimize impacts, including secondary impacts, which could occur beyond the direct construction impacts. These mitigation measures would reduce the scale of the impact to localized areas within the footprint of the construction zone only and limit the potential for impacts beyond the construction zone within sensitive habitats. Mitigation Measures

• During construction, ensure that impacts are contained to as small an areas as possible. All impacts should be contained within the defined road reserve.

• Any sensitive features outside the direct construction zone should be demarcated and no activities should take place within these areas.

• Minimise and restrict clearing to the area required for road construction purposes only and limit disturbance to adjacent undisturbed natural coastal thicket.

• Re-vegetation of disturbed areas must be undertaken with site indigenous species. This can provide a buffer to protect indigenous vegetation from invasion by weeds. The identification of which species are suitable and for which propagules are available from commercial sources needs to be established. A local nursery may need to be established to provide suitable plant material for rehabilitation purposes.



• Implement a weed control plan to avoid establishment and spread of weeds with the long-term measurable outcome the complete absence of alien plants in the road reserve.



Significance Statement Effect Impact Temporal Scale Spatial Scale Severity of Impact

Risk or Likelihood

Total Score


PROPOSED ROUTE – WESTERN AND CENTRAL SECTIONS Without

Mitigation Permanent 4 Localised 1 Moderate 2 Definite 4 11 MODERATE -


- SHORT ROUTE - WESTERN AND CENTRAL SECTIONS

Without Mitigation Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH -

With Mitigation Permanent 4 Localised 1 Moderate 2 Definite 4 11 MODERATE

- PROPOSED Bridge Options (Knysna & Salt Rivers)

Without Mitigation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE

- With

Mitigation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE -

SHORT ROUTE Bridge Options (Knysna and Salt Rivers) Without

Mitigation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

With Mitigation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE

- EASTFORD INTERCHANGE ONLY


- With


8.4.4 Impact 4: Loss of freshwater wetlands Cause and Comment Construction of the road will lead to some direct loss of seasonal marsh wetlands along the route of the proposed road. This will lead to localised loss of wetland habitat and may lead to downstream impacts that affect a greater extent of wetlands or impact on wetland function. Where these habitats are already stressed due to degradation and transformation, the loss may lead to increased vulnerability (susceptibility to future damage) of the habitat. In the western section of the Proposed Route, there is one main wetland area that will be affected by the road that is in the valley between the plantation forests to the west of the Rheenendal road. Construction of the Rheenendal Interchange and the Buffelsvermaak Toll Plaza will also result in some direct loss of these seasonal marsh wetlands. In the central section of the highway (common to both routes) there are also the occasional small wetlands in the area around Concordia which will be affected by the highway. However, these wetlands have already been affected by surrounding urbanization, infrastructure and plantation forests. The potential magnitude of this impact is moderate to severe due to the fact that physical alteration to wetlands can have an impact on the functioning of those wetlands. It will have an impact at a localized scale, but could result in downstream impacts further away and is therefore scored as regional. There may also be secondary impacts beyond the boundaries of the study area, e.g. reduction in water quality downstream of the road. There is one small drainage line on the site of the proposed Groenvlei plaza that drains the entire site towards the Groenvlei lake. Construction of the Groenvlei plaza will therefore lead to some direct loss of seasonal marsh wetland.



The mitigation measures provided aim to minimize impacts, including secondary impacts, which could occur beyond the direct construction impacts, including impacts on the function of downstream wetlands. These mitigation measures would reduce the scale of the impact to localized areas rather than within the broader study area. Mitigation Measures

• Minimise and restrict clearing to the area required for road construction purposes only and limit disturbance to adjacent undisturbed wetland vegetation communities.


• Bridges and/or culverts must be designed and constructed in such a way as to minimise impacts on wetland areas.

• Protection of habitat through implementation of erosion and sediment control measures, including storm-water management.

• Ongoing monitoring and maintenance of re-vegetation works following commissioning of proposal.

• Control alien plants in wetland areas and in disturbed areas by implementing a weed control plan to avoid establishment and spread of weeds.

Significance Statement

Effect Impact Temporal Scale Spatial Scale Severity of

Impact

Risk or Likelihood

Total Score



Mitigation Permanent 4 Regional 3 Moderate 2 Definite 4 13 HIGH-


- BOTH ROUTES – CENTRAL SECTION

Without Mitigation Permanent 4 Study

area 2 Moderate 2 Definite 4 12 HIGH -


- RHEENENDAL INTERCHANGE


- With


BUFFELSVERMAAK TOLL PLAZA Without

Mitigation Permanent 4 Regional 3 Moderate 2 Probable 3 12 HIGH -

With Mitigation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE

- GROENVLEI TOLL PLAZA

Without Mitigation Long-term 3 Regional 3 Moderate 2 Probable 3 11 MODERATE

- With

Mitigation Long-term 3 Localised 1 Slight 1 Probable 3 8 MODERATE -



8.4.5 Impact 5: Fragmentation of natural vegetation Cause and Comment Fragmentation of habitat is one of the most important factors to consider in evaluating the impacts of roads on previously unfragmented areas (Forman & Alexander 1998, Saunders et al. 1991). It will arise due to destruction of habitat in such a way as to divide areas of habitat partially or fully into smaller parts. Fragmentation leads to changes in physical conditions in fragments, increased negative edge effects, isolation of fragments and loss of connectivity with other remnants (Saunders et al. 1991). Fragmentation by transportation corridors such as highways, railways and other linear developments frequently disturb and alter natural disturbance regimes of ecosystems in many areas of the world (Hansen & Clevenger 2005). Larger remnants are less adversely affected by the fragmentation process (Saunders et al. 1991) and it is therefore desirable to keep disturbance as close as possible to existing edges. The barrier effect of roads subdivides populations leading to demographic and genetic consequences (Forman & Alexander 1998). The impact of fragmentation includes the following:

1. Impaired gene flow within fragmented populations, 2. Creation of edges, 3. Breakdown of ecological relationships, e.g. pollinator-plant, 4. Breakdown of migration routes, 5. Reduced functional use, e.g. grazing.

Due to existing disturbance patterns in the landscape in the study area, the proposed road will travel through a relatively modified area. Much of the vegetation already occurs in fragmented patches (see Figure 6.3) and the town of Knysna and its satellite townships have already created hard edges between natural and transformed areas. The two vegetation types of concern with respect to fragmentation are forest and fynbos. For the Proposed Route, in both cases, the proposed road is aligned close to the edge of the existing patches of vegetation. Although habitat loss may occur, no major new fragments will be created and the existing vegetation boundary will merely shift inwards to some degree. For the Short Route, In the case of the forest, the proposed road is aligned close to the edge of the existing patches of vegetation (see Figure 6.3). Although habitat loss may occur, no major new fragments will be created and the existing vegetation boundary will merely shift inwards to some degree. For the fynbos, there is one important patch of fynbos that will be split in half by this road option (Figure 8.6). It will therefore be severely fragmented. Mitigation Measures No mitigation measures are proposed. For the Short Route option, the only possible mitigation to avoid fragmentation of fynbos habitat is to locate the road elsewhere. Significance Statement



Risk or Likelihood

Total Score



Mitigation Permanent 4 Localised 1 Slight 1 Unlikely 1 7 LOW -

With Mitigation Permanent 4 Localised 1 Slight 1 Unlikely 1 7 LOW -


Mitigation Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH -

With Mitigation Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH -



Figure 8.6: Potential fragmentation impact of the proposed (top) and short (bottom) routes on Knysna Shale Fynbos patch. 8.4.6 Impact 6: Loss of populations of threatened plant species Cause and Comment Threatened species include those classified as critically endangered, endangered or vulnerable. For any other species a loss of individuals or localized populations is unlikely to lead to a change in the conservation status of the species. However, in the case of threatened plant species, loss of a population or individuals could lead to a direct change in the conservation status of the species, possibly extinction. This may arise if the proposed infrastructure is located where it will impact on such individuals or populations. There are five species that have been evaluated as having a high chance of occurring along the alignment, four classified as Endangered and one as Vulnerable. Two of the Endangered species could occur in remnant fynbos patches around Eastford and one in the forests north of Concordia. One Vulnerable plant species could occur in any of the remnant patches of fynbos between the Knysna and Goukamma Rivers. The proposed alignment has a low likelihood of affecting any of these four species directly. One of the Endangered species (Acmadenia alternifolia) was recorded during this survey in the fynbos overlooking the bridge over the Knysna estuary. In the case of the Proposed Route, the proposed alignment cuts across the edge of this fynbos and there is a high likelihood of secondary impacts affecting this population. In the case of the Short Route, the proposed alignment cuts directly through the centre of this population and it is definite that direct impacts will destroy this plant population. Since this is a healthy population, its loss could have severe negative impacts on the survival of this species. Loss of this species has global consequences due to the fact that this species does not occur elsewhere.



Mitigation Measures Mitigation measures are proposed for the Proposed Route only. No mitigation is possible for the Short Route since the road alignment cuts directly through the centre of the population and it is probable that no plants will survive from this population if this alignment is selected. Therefore, no mitigation measures will reduce the significance of the impact of the Short Route. Mitigation measures are designed to reduce the likelihood of an indirect impact upon this population.

• Along this section of road, minimise and restrict clearing to the area required for road construction purposes only and limit disturbance to adjacent undisturbed fynbos vegetation communities.


• Sensitive areas adjacent to the road, including all potential habitat for threatened species, must be demarcated and no construction activities or impacts must be permitted to occur across these demarcations. Demarcated areas must be fenced off and no personnel or equipment must be permitted to enter this area.

• Independent monitoring of construction impacts must take place to ensure that no areas of fynbos outside of the construction zone are affected by construction.

• Contractors must be made aware of the highly sensitive nature of the habitat in this area. • Re-vegetation of disturbed areas must be undertaken with site indigenous species. This

can provide a buffer to protect indigenous vegetation from invasion by weeds. The identification of which species are suitable and are available from commercial sources needs to be established. A local nursery may need to be established to provide suitable plant material for rehabilitation purposes.


• Appropriate locating of stockpiles, site offices and infrastructure should be undertaken to limit damage to sensitive vegetation. Stockpiles, site offices and infrastructure should be located within the road reserve and should not be located within areas of fynbos or anywhere close to sensitive sites, even if these occur within the road reserve.

• Implement a weed control plan to avoid establishment and spread of weeds with the long-term measurable outcome the complete absence of alien plants in the road reserve or beyond.




Risk or Likelihood

Total Score


PROPOSED ROUTE Without

Mitigation Permanent 4 International 4 Very severe 8 Probable 3 19 VERY HIGH -

With Mitigation Permanent 4 International 4 Severe 4 May

occur 2 11 MODERATE -

SHORT ROUTE Without

Mitigation Permanent 4 International 4 Very severe 8 Definite 4 20 VERY HIGH -

With Mitigation Permanent 4 International 4 Very severe 8 Definite 4 20 VERY HIGH

-



8.4.7 Impact 7: Loss of populations of threatened animal species Cause and Comment Threatened species include those classified as critically endangered, endangered or vulnerable. For any other species a loss of individuals or localized populations is unlikely to lead to a change in the conservation status of the species. However, in the case of threatened animal species, loss of a population or individuals could lead to a direct change in the conservation status of the species, possibly extinction. This may arise if the proposed infrastructure is located where it will impact on such individuals or populations or the habitat that they depend upon. One of these species, the Blue duiker, is classified as Vulnerable and is therefore the mammal species of highest conservation concern. The Blue Duiker occurs in indigenous evergreen forest and thickets and is known to occur in the study area. It is not, however, likely to be critically affected by the loss of 5 ha of forest close to an existing township, where there is potentially an existing hunting impact on the species. The Knysna Warbler, classified as Vulnerable, is considered to have only a moderate chance of occurring within habitats along the alignment. Suitable habitat includes the vegetation between the Goukamma River and the Knysna River close to drainage lines and the forested valley north of Knysna (adjacent to Concordia). The Knysna leaf-folding frog, classified as Endangered, may be found in fynbos or forest areas, in glades, clearings and roadside pools and in arum blooms. Any wetland, stream or open water area is therefore potential habitat for this species along the proposed alignment. It is considered to have a high chance of occurring within these habitats along the alignment, although not previously recorded there. Mitigation Measures Mitigation measures are designed to reduce direct impacts on potential habitat for threatened animal species, especially the Knysna leaf-folding frog.

• Minimize impacts on wetland areas, as per Impact 4 (above). • Ensure road impacts on the forested area adjacent to Concordia do not affect streams

within the forest • Along this section of road, restrict clearing to the area required for road construction

purposes only and limit disturbance to adjacent undisturbed vegetation. • Contractors must be made aware of the highly sensitive nature of the habitat in this area

and the potential for the occurrence of sensitive species. • Protect habitat through implementation of erosion and sediment control measures,

including effective storm-water management. Significance Statement



Risk or Likelihood

Total Score



Mitigation Permanent 4 International 4 Moderate 2 May occur 2 13 HIGH -

With Mitigation Permanent 4 International 4 Slight 1 Unlikely 1 10 MODERATE

- SHORT ROUTE

Without Mitigation Permanent 4 International 4 Moderate 2 May

occur 2 13 HIGH -

With Mitigation Permanent 4 International 4 Slight 1 Unlikely 1 10 MODERATE

-



8.4.8 Impact 8: Secondary impacts on vegetation due to changes in runoff and drainage, soil erosion and increase in silt loads and sedimentation

Cause and Comment Roads and interchanges crossing landscapes cause local hydrological and erosion effects resulting in major peak-flow and sediment impacts (Forman & Alexander 1998). This may occur around construction sites, but also in areas where the infiltration rates of the landscape are changed due to an impermeable surface being constructed. Increased runoff associated with roads may increase the rates and extent of erosion, reduce percolation and aquifer recharge rates, alter channel morphology and increase stream discharge rates. Consequences may include:

1. Increased loss of soil; 2. Loss of or disturbance to indigenous vegetation, especially in wetlands; 3. Loss of sensitive habitats, especially in wetlands; 4. Impairment of wetland function; 5. Change in channel morphology in downstream wetlands, potentially leading to loss

of wetland vegetation; and 6. Reduction in water quality in wetlands downstream of road.

This impact will affect all interchange options where natural vegetation will be affected. There is one small drainage line on the site of the proposed Groenvlei plaza that drains the entire site perpendicularly away from the existing road towards the Groenvlei lake (see figure 8.7 below). Construction of the Groenvlei plaza will therefore lead to some direct loss of seasonal marsh wetland. This will lead to localised loss of wetland habitat and may lead to downstream impacts that affect a greater extent of wetlands or impact on wetland function. The loss may lead to increased vulnerability (susceptibility to future damage) of the habitat. The potential magnitude of this impact is moderate to severe due to the fact that physical alteration to wetlands can have an impact on the functioning of those wetlands. It will have an impact at a localized scale, but could result in downstream impacts further away, especially on the Groenvlei lake, and is therefore scored as regional. There may therefore be secondary impacts beyond the boundaries of the study area, e.g. reduction in water quality downstream of the road. Similarly, the construction of the proposed Buffelsvermaak plaza will lead to hydrological impacts into the drainage line that occurs downslope of the site. Mitigation Measures

• A stormwater management plan is required to manage potential runoff problems during construction and operation.

• Following construction, rehabilitation of disturbed areas is required. • Restrict clearing to the area required for road construction purposes only and limit

disturbance to adjacent undisturbed wetland vegetation communities. • Re-vegetation of disturbed areas must be undertaken with site indigenous species. This

can provide a buffer to protect indigenous vegetation from invasion by weeds. The identification of which species are suitable and are available from commercial sources needs to be established. A local nursery may need to be established to provide suitable plant material for rehabilitation purposes.

• Bridges and/or culverts must be designed and constructed in such a way as to minimise impacts on wetland areas.



Figure 8.7: Google image of Groenvlei plaza position (within 4 marked points straddling road). Wetland areas (seasonal) are shown within the blue polygon. The white bar is 100 m long. Significance Statement



Risk or Likelihood

Total Score



Mitigation Long-term 3 Study area 2 Moderate 2 Probable 3 10 MODERATE -

With Mitigation Long-term 3 Study area 2 Slight 1 May


SHORT ROUTE Without




ALL INTERCHANGES Without




GROENVLEI TOLL PLAZA Without

Mitigation Long-term 3 Regional 3 Moderate 2 Probable 3 11 MODERATE -







Risk or Likelihood

Total Score


BUFFELSVERMAAK TOLL PLAZA Without




8.4.9 Impact 9: Establishment and spread of declared weeds and alien invader plants Cause and Comment Major factors contributing to invasion by alien invader plants include high disturbance, fostering/utilisation as hedges, woodlots or fruit trees, negative grazing practices, and deforestation (Zachariades et al. 2005). Exotic species are often more prominent on roadsides than further away (Gelbard & Belnap 2003, Watkins et al. 2003). Transportation corridors may encourage the invasion by non-native plant species by: (1) altering disturbance regimes in adjacent plant communities, both directly by creating gaps and by changing the plant species composition, and indirectly by altering environmental conditions such as light and soil moisture. (2) Vehicle traffic on roads aids in the dispersal of non-native species into surrounding habitat by causing air turbulence and by acting as vectors for spread of seeds and vegetative plant parts (Hansen & Clevenger 2005). This impact will affect all interchange and toll plaza options where natural vegetation will be affected. Mitigation Measures

• Following construction, rehabilitation of disturbed areas is required. • Re-vegetation of disturbed areas must be undertaken with site indigenous species. This

can provide a buffer to protect indigenous vegetation from invasion by weeds. The identification of which species are suitable and for which propagules are available from commercial sources needs to be established. A local nursery may need to be established to provide suitable plant material for rehabilitation purposes.

• Avoid translocating stockpiles of topsoil from one place to another in order to avoid translocating soil seed banks of alien species.

• Keep construction of access roads to a minimum. • During operation, the clearing of alien plants within the road servitude is required to control

alien invasions. This is mandatory, according to current legislation. Significance Statement



Risk or Likelihood

Total Score



Mitigation Medium-

term 2 Study area 2 Severe 4 Probable 3 11 MODERATE -

With Mitigation

Medium-term 2 Study area 2 Slight 1 May

occur 2 7 LOW -

SHORT ROUTE Without

Mitigation Medium-


With Mitigation


occur 2 7 LOW -

ALL INTERCHANGES Without






Risk or Likelihood

Total Score




ALL TOLL PLAZAS Without

Mitigation Medium-


With Mitigation


occur 2 7 LOW -

8.4.10 Impact 10: Preventing free movement of animals Cause and Comment Building the road may cause barriers to movement of animals. However, the potential barrier is on the margin of existing vegetation patches thus resulting in little fragmentation (see Impact 5 on fragmentation impacts). For the Proposed Route, there are two areas that may become more isolated with the construction of the road, the headland overlooking the bridge over the Knysna estuary and the area between the Knysna and Goukamma Rivers. For the Short Route, there is one area that may become more isolated with the construction of the road, the headland overlooking the bridge over the Knysna estuary. The only animal likely to require free movement is the Blue duiker, which occurs in the forest, not in the two areas mentioned above, and is unlikely to be impeded by a road between the forest and an urban area. Mitigation Measures None proposed. Significance Statement



Risk or Likelihood

Total Score



Mitigation Long-term 3 Study area 2 Slight 1 Unlikely 1 7 LOW -

With Mitigation Long-term 3 Study area 2 Slight 1 Unlikely 1 7 LOW -


Mitigation Long-term 3 Study area 2 Slight 1 Unlikely 1 7 LOW -

With Mitigation Long-term 3 Study area 2 Slight 1 Unlikely 1 7 LOW -

EASTFORD TOLL PLAZA ONLY Without

Mitigation Medium-

term 3 Study area 2 Severe 4 Probable 3 12 HIGH -

With Mitigation

Medium-term 3 Localized 1 Severe 4 May


8.4.11 Impact 11: Increased risk of veld fires Cause and Comment During construction there is a higher risk of veld fires around construction sites due to the use of fires for cooking and warmth by construction workers. During operation, there is a similar higher risk of veld fires along the road due to poor habits by road users as well as potential spreading of fires during the burning of fire breaks in road servitudes. Impacts that may arise from this may include:

1. Damage to sensitive habitats, especially damage to forest and woodland vegetation and change in species composition in fynbos;



2. Damage to populations of sensitive plant species; 3. Loss of vegetation biomass; and 4. Increased soil erosion due to loss of vegetation cover.

The fynbos vegetation overlooking the bridge over the Knysna River is vulnerable to incorrect fire regimes due to the presence of the Endangered plant species that occur there. The Eastford plaza is therefore the option with the greatest cause for concern with regards to the increased risk of fires. The potential severity of the impact is high due to potential cumulative effects of regular fires on fynbos species and especially the Endangered plant species. The mitigation measures are aimed at reducing the probability of fires and reducing the spread of fires, thus reducing the scale of the impact. Mitigation Measures

• During construction, management of fires emanating from construction camps and education of the work force concerning management of fires is required.

• Camp fires at construction sites must be strictly controlled to ensure that no veld fires are caused. This is especially important where fires may affect sensitive habitats.

• During operation, a burning programme should be compiled to reduce fuel loads in the road reserve without implementing a fire frequency that is too high for the affected vegetation.




Risk or Likelihood

Total Score



Mitigation Medium-

term 3 Study area 2 Moderate 2 Probable 3 10 MODERATE -

With Mitigation

Medium-term 3 Localized 1 Slight 1 May

occur 2 7 LOW -

SHORT ROUTE Without

Mitigation Medium-

term 3 Study area 2 Moderate 2 Probable 3 10 MODERATE -

With Mitigation

Medium-term 3 Localized 1 Slight 1 May

occur 2 7 LOW -

8.4.12 Impact 12: Loss of protected trees Cause and Comment There is a number of tree species that are protected according to Government Notice no. 1012 under section 12(I)(d) of the National Forests Act, 1998 (Act No. 84 of 1998). In terms of section 1 5(1) of the National Forests Act, 1998 “no person may cut, disturb, damage or destroy any protected tree or possess, collect, remove, transport, export, purchase, sell donate or in any other manner acquire or dispose of any protected tree or any forest product derived from a protected tree, except under a license granted by the Minister to an (applicant and subject to such period and conditions as may be stipulated”. A number of species was recorded in the study area that appear on this list, including the following: Curtisia dentata, Podocarpus falcatus and Sideroxylon inerme subsp. inerme. There is also a high likelihood of Ocotea bullata and Podocarpus latifolius occurring along the alignment, although it was not seen. Mitigation Measures

• A targeted survey of protected trees is required to identify any individuals of protected species.

• A permit must be obtained from Department of Water Affairs and Forestry for the removal or damage of any protected tree species.





Impact

Risk or Likelihood

Total Score



Mitigation Medium-

term 3 Localized 1 Moderate 2 Probable 3 9 MODERATE -

With Mitigation

Medium-term 3 Localized 1 Slight 1 Probable 3 8 MODERATE

- SHORT ROUTE

Without Mitigation

Medium-term 3 Localized 1 Moderate 2 Probable 3 9 MODERATE

- With

Mitigation Medium-

term 3 Localized 1 Slight 1 Probable 3 8 MODERATE -

8.4.13 Impact 13: Loss of salt marsh vegetation Cause and Comment Construction of bridges will lead to direct loss of salt marsh vegetation in the footprint of the proposed bridge. Where these habitats are already stressed due to degradation and transformation, the loss may lead to increased vulnerability (susceptibility to future damage) of the habitat. The overall effect of habitat loss may be increased by secondary impacts that alter the nature of habitats adjacent to the bridge, especially in terms of the overall hydrology of the estuary. Other than direct loss of vegetation, the bridge may alter water flow patterns and thus lead to a change or further loss of salt marsh vegetation. Since specific conservation targets for the Knysna Estuary are not yet known, it is unknown whether this impact will affect the conservation status of habitats within the estuary. In the case of the Proposed Route, the main area where the proposed bridge will impact on salt marsh vegetation is on the floodplain of the Knysna River estuary crossing. There is another patch of salt marsh vegetation within the Salt River estuary at the site of the proposed bridge. For the Knysna River crossing, impacts will be contained within the footprint of the proposed bridge and there will be little lateral spread of direct impacts. The bridge with embankments (bridge type A) will have a more significant impact on floodplain vegetation (primarily salt marsh vegetation) than the completely piered structure Bridge (bridge type B), because the piered structure will eventually (after construction) allow floodplain processes, e.g. water movement, to continue underneath the bridge structure. The Cable Stayed Bridge (Bridge type C) will have the same impact as that of bridge type B. The Short Road option makes use of an existing bridge, but will require the construction of a major viaduct 300m east of White Bridge that lifts the highway over the existing lagoon road and up into the ravine above on its way to the Eastford interchange. This will require some widening of the existing fill area over the mud flats/salt marshes between White Bridge and the viaduct. In addition, during construction the existing traffic will need to be diverted around the highway and a temporary road will need to be constructed over the mud flats during construction of this section. It is therefore expected that impacts on salt marsh vegetation for this option will be greater than the “Proposed” road option. The main area where the proposed bridge will impact on salt marsh vegetation is on the floodplain of the Knysna River estuary crossing. Mitigation Measures The mitigation measures provided aim to minimize secondary impacts, which could occur beyond the direct construction impacts. Mitigation measures cannot reduce direct construction impacts.

• During construction, ensure that impacts are contained to as small an area as possible, i.e. construction equipment should not be stored or driven outside the defined road reserve. This will ensure that there is little lateral spread of direct impacts.

• Restrict clearing to the area required for road construction purposes only and limit disturbance to adjacent undisturbed salt marsh vegetation.



• Machinery and vehicles should not be driven across salt marshes outside of the expected impact zone.

• All salt marshes outside the impact zone must be designated as sensitive and no access to these areas by construction contractors or equipment must be permitted.

• An independent Environmental Control Officer must be present to monitor impacts on salt marshes and prevent undue damage.


• Implement a weed control plan to avoid establishment and spread of weeds with the long-term measurable outcome the complete absence of alien plants in the road reserve.

• A comprehensive rehabilitation plan must be developed for disturbed areas. Significance Statement



Risk or Likelihood

Total Score


PROPOSED ROUTE (A: Short Bridge with embankment) Without

Mitigation Permanent 4 Study area 2 Severe 4 Definite 4 14 HIGH -

With Mitigation Permanent 4 Study area 2 Moderate 2 Definite 4 12 HIGH -

PROPOSED ROUTE (B: Piered bridge structure) Without

Mitigation Long-term 3 Study area 2 Severe 4 Definite 4 13 HIGH -

With Mitigation Long-term 3 Study area 2 Moderate 2 Definite 4 11 MODERATE

- PROPOSED ROUTE (C: Cable Stay Bridge)

Without Mitigation Long-term 3 Study area 2 Severe 4 Definite 4 13 HIGH -

With Mitigation Long-term 3 Study area 2 Moderate 2 Definite 4 11 MODERATE

- SHORT ROUTE – White Bridge & Viaduct

Without Mitigation Permanent 4 Study area 2 Severe 4 Definite 4 14 HIGH -

With Mitigation Permanent 4 Study area 2 Severe 4 Definite 4 14 HIGH -

8.4.14 Comparison of alternatives Alternative routes are compared here in terms of the relative impacts that they may have. The impacts in each of these sections of the highway are summarized in table 8.7 below. Table 8.7: Summary of Impacts on the Terrestrial Ecology for the Knysna Toll Highway Project

Impact Significance Impacts Without Mitigation With Mitigation Impact 1: Loss of forest Both Routes-Central Section HIGH - MODERATE - Do Nothing N/A N/A Impact 2: Loss of fynbos Proposed-Western section HIGH - HIGH - Short Route-Western section VERY HIGH - VERY HIGH - Rheenendal Interchange (PR) MODERATE - MODERATE - Eastford Interchange (Both routes) MODERATE - MODERATE - Eastford Plaza (SR) MODERATE - MODERATE - Groenvlei Plaza (Both routes) MODERATE - MODERATE - Do Nothing N/A N/A Impact 3: Loss of coastal thicket



Impact Significance Impacts Without Mitigation With Mitigation Both Routes - Central Section HIGH - MODERATE - Proposed-Western section MODERATE - MODERATE - Short Route-Western section HIGH - MODERATE - Knysna River Bridge (PR) MODERATE - MODERATE - Knysna River White Bridge (SR) MODERATE - MODERATE - Salt River Bridge (Both Routes) MODERATE - MODERATE - Salt River Interchange (Both routes) MODERATE - MODERATE - Do Nothing N/A N/A Impact 4: Loss of freshwater wetlands Both Routes - Central Section MODERATE - MODERATE - Proposed-Western section HIGH - MODERATE - Short Route-Western section HIGH - MODERATE - Rheenendal Interchange (PR) MODERATE - MODERATE - Buffelsvermaak Plaza (PR) HIGH - MODERATE - Groenvlei Plaza (Both Routes) MODERATE - MODERATE - Do Nothing N/A N/A Impact 5: Fragmentation of natural vegetation Both Routes - Central Section LOW - LOW - Proposed-Western section LOW - LOW - Short Route-Western section HIGH - HIGH - Do Nothing N/A N/A Impact 6: Loss of populations of threatened plant species Both Routes - Central Section VERY HIGH - MODERATE - Proposed VERY HIGH - MODERATE - Short Route VERY HIGH - VERY HIGH - Do Nothing N/A N/A Impact 7: Loss of populations of threatened animal species Both Routes - Central Section HIGH - MODERATE - Proposed-Western section HIGH - MODERATE - Short Route-Western section HIGH - MODERATE - Do Nothing N/A N/A Impact 8: Change in runoff and drainage leading to soil erosion and increase in silt loads and sedimentation Proposed MODERATE - MODERATE - Short Route MODERATE - MODERATE - Groenvlei Interchange MODERATE - MODERATE - Rheenendal Interchange (PR) MODERATE - MODERATE - Eastford Interchange (Both) MODERATE - MODERATE - Salt River Interchange (Both) MODERATE - MODERATE - Groenvlei Plaza (Both routes) MODERATE - MODERATE - Buffelsvermaak Plaza (PR) MODERATE - MODERATE - Do Nothing N/A N/A Impact 9: Establishment and spread of declared weeds and alien invader plants Proposed MODERATE - LOW - Short Route MODERATE - LOW - Groenvlei Interchange (Both) MODERATE - LOW - Rheenendal Interchange (PR) MODERATE - LOW - Eastford Interchange (Both) MODERATE - LOW - Salt River Interchange (Both) MODERATE - LOW - Do Nothing N/A N/A Impact 10: Preventing free movement of animals Proposed-Western section LOW - LOW - Short Route-Western section LOW - LOW - Do Nothing N/A N/A



Impact Significance Impacts Without Mitigation With Mitigation Impact 11: Increased risk of veld fires Proposed-Western section MODERATE - LOW - Short Route-Western section MODERATE - LOW - Eastford Toll Plaza (SR) MODERATE - LOW - Do Nothing N/A N/A Impact 12: Loss of protected trees Proposed MODERATE - MODERATE - Short Route MODERATE - MODERATE - Do Nothing N/A N/A Impact 13: Loss of salt marsh vegetation Proposed (A: bridge with embankment) HIGH - HIGH - Proposed (B: piered bridge structure) HIGH - MODERATE - Proposed (C: cable stay bridge HIGH - MODERATE - Short Route HIGH - HIGH - Do Nothing N/A N/A

There are some impacts which are general and apply to all sections of both highway options (Impacts 8, 9, 11 &12). The eastern section has no impacts that are specific to it. The central section of the highway, which is common to both routes, has eight impacts, two of which are very high and another two are High. All these impacts can be mitigated to moderate levels. Central Section Without Mitigation With Mitigation 1) Loss of Forest HIGH - MODERATE - 2) Loss of fynbos MODERATE - MODERATE - 3) loss of coastal thicket HIGH - MODERATE - 4) Loss of freshwater wetlands MODERATE - MODERATE - 5) Fragmentation of natural vegetation LOW - LOW - 6) Loss of populations of threatened plant species VERY HIGH - MODERATE - 7) Loss of populations of threatened animal species VERY HIGH - MODERATE - 10) Preventing free movement of animals LOW - LOW - The western section is where the most significant impacts occur and where the major differences between the two routes occur. The main and most significant differences relate to the impact on fynbos, coastal thicket and salt marsh vegetation which are all higher for the Short Route options and more difficult to mitigate.

Proposed Route

Short Route

Impacts

Without Mitigation

With Mitigation

Without Mitigation With Mitigation

2) Loss of fynbos HIGH - HIGH - VERY HIGH - VERY HIGH - 3) loss of coastal thicket MODERATE - MODERATE - HIGH - MODERATE - 4) Loss of freshwater wetlands HIGH - MODERATE - HIGH - MODERATE - 5) Fragmentation of natural vegetation LOW - LOW - HIGH - HIGH - 6) Loss of populations of threatened plant species VERY HIGH - MODERATE - VERY HIGH - VERY HIGH - 7) Loss of populations of threatened animal species HIGH - MODERATE - HIGH - MODERATE - 10) Preventing free movement of animals LOW - LOW - LOW - LOW - 11) Increased risk of veld fires MODERATE - LOW - MODERATE - LOW -

13) Loss of salt marsh vegetation HIGH - MODERATE - (bridge B&C) HIGH - HIGH -



The primary reason for the high significance of these three impacts on the western section of the Short Route option versus the Proposed Route is the fact that the route passes through an area of fynbos on the headland above the bridge crossing the Knysna estuary, in which a population of an Endangered plant species occur. The existence of this population is confirmed and was observed during fieldwork. This population is directly in the path of the proposed road and it would not be possible to re-align the road to avoid it. Even if a re-alignment was possible, the entire area of fynbos is important for meta-population dynamics within this plant population and any disturbance to this area of fynbos would therefore jeopardize the survival of this population and, due to its high threatened status, the species itself. For the Proposed Route, the construction of the bridge has one impact in the western section assessed as having HIGH significance for bridge design A and B. For bridge type A (short bridge with embankments), the significance of this impact cannot be reduced significantly with mitigation measures, whereas for bridge type B (on 13 piers) it can be reduced to MODERATE. This impact is “Loss of salt marsh vegetation”. This indicates that bridge types B and C would be preferred from an ecological perspective, specifically due to impacts on salt marsh vegetation. The significance of this impact for the Short Route option is HIGH with and without mitigation. The primary reason for this difference in significance for this impact is due to the fact that, for a new crossing of the estuary (bridge construction), impacts will be contained to the footprint of the infrastructure, whereas upgrading of the existing bridge will result in adjacent disturbance due to the requirement for diverting the existing traffic onto a temporary road during construction. The existing bridge would also require the construction of a large causeway to provide sufficient elevation on the eastern bank. The Proposed Route is therefore considered to be preferable. The interchange options differ for the short and proposed alignments. The proposed alignment will include the Rheenendal Interchange, which has been evaluated as having two impacts of moderate significance, as follows:

• Loss of freshwater wetlands • Loss of fynbos

These impacts would not occur for the Short Route option, because the Rheenendal Interchange would not be built if this route option was selected. The Eastford Interchange would lead to one impact of moderate significance, namely “loss of fynbos” and the Salt River Interchange would result in one impact of moderate significance, namely “loss of coastal thicket”. The two interchanges would therefore have impacts of similar significance. From an ecological perspective, neither interchange is therefore preferable. For all interchanges, there may also be two additional impacts, one of moderate significance and one of low significance, namely “change in runoff and drainage” and “Establishment and spread of declared weeds and alien invader plants”. There are ecological impacts resulting from all of the west bound toll plaza sites. The Eastford toll plaza may lead to the impact “loss of fynbos”. Increased risk of veld fires is a concern around all toll plazas, but the potential severity of this impact is worst for the Eastford plaza due to the proximity of the fynbos habitat in which an Endangered plant species may occur. This impact has been assessed as having potentially HIGH significance, but could be reduced to MODERATE with the implementation of mitigation measures. The Groenvlei is expected to lead a loss of some seasonal marsh wetland and the drainage for the entire site is towards the Groenvlei lake within the Goukamma Reserve. There is some concern therefore about potential secondary downstream impacts on the lake. This is rated as a MODERATE impact that could be managed. The Buffelsvermaak toll plaza near the Rheenendal interchange has one impact assessed as having HIGH significance, which can be reduced to MODERATE significance with mitigation measures. This impact is “Loss of freshwater wetlands” due to the presence of a valley bottom wetland system that would be affected by the road and toll plaza. This plaza would also result in a change in runoff and drainage leading to soil erosion and an increase in silt loads and sedimentation



8.4.15 Conclusion and recommendations The requirements of this study were to undertake an ecological assessment to describe the vegetation, flora and fauna in the study area. The study identified a number of vegetation types that are considered to have high conservation value. These include fynbos, all remnants of which belong to Endangered vegetation types, forest, coastal thicket, salt marsh and some freshwater wetlands. Construction of the western section of the highway, whichever alternative is selected, is likely to have significant impacts on vegetation or threatened plant or animal species. From an ecological perspective, the overall assessment of impacts indicates that the Short Route option will have one impact of VERY HIGH significance (Loss of populations of a threatened plant species), which is sufficient to prevent the implementation of that option. The Proposed Route option has one impact of HIGH significance (Loss of salt marsh vegetation), which may be considered to constitute a severe environmental effect which requires careful control and implementation of mitigation measures. It is recommended that the following studies are undertaken:

1. Undertake a targeted survey of the population of Acmadenia alternifolia to determine the number of individuals and their total distribution in the area of fynbos where they occur. This will be necessary in order to determine the boundaries of the population, establish appropriate buffer zones and determine the outer limits of the sensitive area that needs to be taken into consideration for mitigation of potential impacts on this species.

2. Undertake a targeted survey of potential habitats for the Endangered Knysna leaf-folding frog to determine whether it occurs along the alignment or not. This is necessary in order to improve the confidence in the assessment of the potential impact of the proposed road on threatened animal species.

3. Undertake a targeted survey of all protected trees occurring within the selected alignment in order to provide the information required for applying for a permit for the potential removal or damage of any of these trees. The proposed alignments are almost certain to impact on such protected trees and it is a legal requirement to obtain this information before a permit can be obtained, which will need to be done before construction of the road can take place. The species most likely to be affected by construction of the road are Sideroxylon inerme subsp. inerme, Mimusops caffra and Podocarpus latifolius, all recorded in habitats along the alignments.

The following is recommended with respect to sensitive sites in the study area:

1. Habitat suitable for threatened species that are known to occur along the alignment (Acmadenia alternifolia and Aspalathus bowieana) should not be affected by the proposed road. The habitats and, where available, a 200 m buffer around them should be protected from any impacts associated with the construction of the road (see Figures 6.8.1 & 6.8.2 in Specialist Volume Part 1). In the absence of any legislative guidelines, the distance of 200 m is based on various published sources. A buffer zone is a collar of land that filters out inappropriate influences from surrounding activities (Shafer, 1999), also known as edge effects, including the effects of invasive plant and animal species, physical damage and soil compaction caused through trampling and harvesting, abiotic habitat alterations and pollution. Buffer zones can also provide more landscape needed for ecological processes such as fire (Shafer, 1999). This distance of 200 m therefore provides some protection from deleterious edge effects and is considered to be the minimum amount to provide these species with a chance of survival.

2. No construction or secondary impacts should occur within the core or buffer areas. This includes shading by bridges, changes in runoff patterns and geomorphological impacts, such as changes to ground-water movement, slope stability, etc.



On the basis of these recommendations, the Short Route option will not be possible to build without having direct impacts on populations of the threatened species, Acmadenia alternifolia (Figure 6.8.1 in Specialist Volume Part 1). The SANRAL Proposed alignment also occurs within close proximity to suitable habitat. It is essential to determine the boundaries of this population in order to assess the potential impact that the proposed alignment may have on this species.



9 IMPACTS AND MITIGATION: THE SOCIO-ECONOMIC

ENVIRONMENT 9.1 Introduction The subsections which follow discuss the potential impacts of the Knysna Toll Highway on three main aspects of the socio-economic Environment. This includes all the social, heritage, traffic, landscape, visual, noise and economic impacts. A large number of these impacts are general impacts that are not specific to any particular site or portion of the highway alternatives. The only exception is the noise impact which varies along the route depending on topography and the types of land use and density of settlement around the highway. As with the other site specific impacts, the discussion of these impacts focuses on its relative significance for various sections and features of the highway. For ease of comparison between the alternatives, the highway has been divided up into three sections – 1) the central section which is common to both the ‘Proposed’ and the ‘Short’ routes, 2) the western section from Buffelsvermaak to the Eastford interchange, and 3) the eastern section from the Uniondale Interchange to Brackenhill. The western and eastern sections had different routes for the ‘Proposed’ and ‘Short’ routes. The extent to which these impacts are relevant to the construction and operational phases. 9.2 Social Impacts In this section of the report the social impacts as identified will be described and assessed. These impacts do not include the eight economic, traffic, visual and noise impacts that are mentioned in the Social Impact Assessment but which overlap with the impacts identified in the Economic, Traffic, Visual and Noise Impact Assessments. Based on the various issues raised across all sections of the route the following social impacts have been identified:

1. Increased cost of doing business and concomitant loss of income 2. Increased cost of accessing services and employment for marginal communities 3. Increased cost of accessing services and employment for advantaged communities 4. Increase in pollutants along the toll road area 5. Increase in pollutants in the CBD area 6. Increased HIV/AIDS and STD risks associated with construction gangs and increased

truck traffic 7. Secondary effects such as potential increased crime 8. Resettlement of affected households 9. Loss of access to natural capital

Each of these impacts is described and assessed below. Both the Proposed Route and the Short Route are assessed as well as the Do Nothing option. 9.2.1 Impact 1: Increased cost of doing business and concomitant loss of income Description of impact: The introduction of tolls on the highway may have a negative impact on the cost of living and doing business in Knysna and surrounds. Mitigation objective: Limit financial losses to local communities and businesses that may be caused by tolling. Mitigation Measures:

• Introduce concessions for local business;



Assessment: In some respects this is one of the more vocally articulated arguments against the Toll roads. The introduction of a toll has the potential to lead to a loss of employment and consequently the reduction in community income, exacerbating poverty. Tolling will impact on those undertaking longer journeys and many of those travelling for work purposes. For marginal operations this, it has been stated, could lead to their demise. However this needs to be balanced by the increased cost of living and doing business because of traffic congestion and potential loss of tourism associated with the Do Nothing option. The traffic and economic studies indicate that there are significant vehicle operating costs and health costs associated with the Do Nothing option – much higher than costs of tolls. In fact the economic cost-benefit analysis found that the Proposed Route was a better alternative than either the Short Route or the Do Nothing (Do-nothing) option.7 Without mitigation: This impact is assessed with a medium level of confidence. During the operational phase, for both the Proposed and Short Routes, this impact will be negative and will definitely occur permanently over the study area with a moderate severity. The overall significance of this impact will be high. For the No Toll Highway option, the impact will also be negative and high with no option for mitigation measures. With mitigation: If the mitigation measures suggested for the operational phase are successfully implemented, then although the impact remains negative for both the Proposed and Short Routes, the severity will decrease from moderate to slight with an assocaited decrease in the overall significance from high to moderate. Significance Statement

Effect Phase Temporal


Risk or Likelihood

Total Score


Proposed Route- Before Mitigation Construction NA NA NA NA NA Operation Perm 4 Study Area 2 Moderate 2 Definite 4 12 HIGH -

Proposed Route- After Mitigation Construction NA NA NA NA NA

Operation Perm 4 Study Area 2 Slight 1 Definite 4 11 MODERATE -

Short Route- Before Mitigation Construction NA NA NA NA NA

Operation Perm 4 Study Area 2 Moderate 2 Definite 4 12 HIGH-

Short Route- After Mitigation Construction NA NA NA NA NA


No Toll Highway- Before Mitigation


No Toll Highway- After Mitigation Operation N/Am N/A N/A N/A N/A

7 See EIA Specialist Report: Economic Impact Assessment (2008). Prepared by Imani.



9.2.2 Impact 2: Increased cost of accessing services and employment for marginal

communities Description of impact: The introduction of tolls on roads that have not previously been subject to tolling will have a negative impact on the cost of accessing points of employment and/or services for disadvantaged residents of outlying settlements. In this regard disadvantaged residents are defined as those with relatively low levels of disposable income and dependent on public transport.8 For the “No Toll” option increased levels of congestion will also impact negatively on travel costs, Mitigation objective: To ensure that the toll costs do not result in greater economic hardship for marginalized communities. Mitigation measures:

• Reduce the number of toll points; • Introduce concessions for public transport providers.

Assessment: The communities potentially most affected are likely to be those in the dormitory suburbs and peripheries around Knysna. Also affected will be the marginal workforce who commutes from west and east of Knysna into the town. Additional costs associated with tolls incurred by marginal households will have negative consequences for their viability For the “No Toll” Highway option there will be increased time and travel costs associated with congestion as well as increased health costs.9 Without mitigation: This impact is assessed with a medium level of confidence and applies to only the operational phase. For both the Proposed and Short Routes, this impact will definitely occur over the study area and will be permanent with a moderate severity. The impact will be negative with an overall significance that is high. For the No Toll Highway option, the significance of this impact would also be high, with no possible mitigation measures. With mitigation: If the suggested mitigation measures are successfully implemented, then although the impact remains negative, the severity of the impact can be decreased from moderate to slight and overall significance from high to moderate for both the Proposed and Short route options. Significance Statement



Risk or Likelihood

Total Score


Proposed Route- Before Mitigation Construction NA NA NA NA NA Operation Perm 4 Study Area 2 Moderate 2 Definite 4 12 HIGH-





8 The potential Groenvlei Toll Plaza would have less impact on the communities at Rhenendaal, Belvidere, Brenton-on-Sa and Buffles Bay than the

Buffelswermaak/Rhenendaal and Estford Plazas. 9 See EIA Specialist Study: Traffic Report (2008). Prepared by BKS.





Risk or Likelihood

Total Score






No Toll Highway- After Mitigation Operation N/A N/A N/A N/A N/A N/A 9.2.3 Impact 3: Increased cost of accessing services and employment for advantaged

communities Description of impact: The introduction of tolls onto roads that have not as yet been subject to tolling will have a negative impact on the cost of accessing services for all road users even those regarded as wealthier and more advantaged. Again this should be balanced against higher time, travel and accident costs associated with congestion if the Toll Road does not go ahead.10 Mitigation objective: To ease the cost of accessing services and employment for advantaged communities. Mitigation measures:

• Introduce concessions for local commuters. Assessment: In this regard, advantaged communities are defined as those with relatively higher levels of disposable income. In this case “higher levels of disposable income” would mean the likelihood of access to private transport. Most of these road users are likely to be travelling on a regular basis between wealthier outlying areas of Knysna to town itself. Without mitigation: This impact is assessed with a medium level of confidence. During the operation phase of both the Proposed and Short Routes, this impact will definitely occur over the study area and will be permanent with a slight severity. This impact will be negative and its overall significance for both route options will be moderate. For the No Toll Highway option, the overall significance of this negative impact will be high with no mitigation measures. With mitigation: It is unlikely that mitigation will alter this impact to any significant degree as the more fiscally advantaged commuters are unlikely to be greatly affected by the tolls. Mitigation while still strongly suggested, in the form of concessions, is not likely to have a major impact. Significance Statement



Risk or Likelihood

Total Score


Proposed Route- Before Mitigation Construction NA NA NA NA NA Operation Perm 4 Study Area 2 Slight 1 Definite 4 11 MODERATE -

Proposed Route- After Mitigation Construction NA NA NA NA NA Operation Perm 4 Study 2 Slight 1 Definite 4 11 MODERATE -

10 Again, the potential Groenvlei Toll Plaza would have less impact on the communities at Rhenendaal, Belvidere, Brenton-on-Sa and Buffles Bay

than the Buffelswermaak/Rhenendaal and Estford Plazas.





Risk or Likelihood

Total Score


Area Short Route- Before Mitigation

Construction NA NA NA NA NA





Operation Perm 4 Study Area 2 Moderate 2 Definite 4 12 HIGH -

No Toll Highway- After Mitigation

Operation Perm 4 Study Area 2 Moderate 2 Definite 4 12 HIGH -

9.2.4 Impact 4 and 5: Increase in health risks and traffic generated pollutants Description of impact: Construction will result in the emission of various air pollutants characteristic of the use of petrol and diesel-powered vehicles and equipment. The anticipated air pollutants to be emitted include nitrogen oxide, hydrocarbons, carbon monoxide, sulphur dioxide and particulate matter. Vehicular traffic during the operational phase may also contribute to the general overall exhaust emissions, which can negatively impact on peoples’ health. Mitigation objective: Ensure that air pollutants are in accordance with the World Heath Organisation (WHO) guidelines. Mitigation measures:

• Regularly monitor levels of air pollution; • Work in conjunction with the appropriate authorities in enforcing air pollution by-laws; • During construction all vehicles and construction machinery should be maintained to a

standard that minimises pollutants; • The recommendations of the air pollution specialists must be complied with.

Assessment: Along the proposed highway an increase in health risk and traffic generated pollutants could be a particular issue where toll plazas are close to residential areas. These are however fairly remote from points of high density. The bypass, where it passes close to the informal settlements could increase health risks from pollutants. Construction is also likely to increase pollutants and dust. The “No Toll Highway” will have increased congestion and hence traffic through the town itself and therefore have negative impacts. Without mitigation: This impact is assessed with a medium level of confidence. Two areas will be affected by this impact; the first is along the toll route itself and the second in the CBD. In the first area (i.e. along the toll route), during the construction phase for the Proposed and Short Routes, this impact will be probably occur on a localised scale over the short-term and will be moderately severe. The overall significance of this negatve impact will therefore be low. During the operational phase for both route options however, this impact will probably occur permanently over a localised scale with a slight severity. The overall significance of this negative impact will increase to moderate. In the second area (i.e. the CBD), during the operational phase of both route options, the impact may occur permanently over a localised scale and will be slightly beneficial with an overall significance of moderately beneficial.



For the No Toll Highway option in the CBD area, the impact would probably be negative, occur permanently over a localised scale with a slight severity and an overall significance of moderate. With mitigation: If the suggested mitigation measures are successfully implemented, then in the first area (i.e. along the toll route), during the construction phase for both the Proposed and Short Routes, the severity of this negative impact can be reduced from moderate to slight however, the overall significance of this impact will still remain low. However during the operational phase for both route options, the severity of this negative impact and overall significance will remain slight and moderate respectively. In the second area (i.e. the CBD), during the operational phase of both route options, even with successful implementation of mitigation measures, the impact will remain slightly beneficial with an overall significance of moderately beneficial. As for the above, for the No Toll Highway option in the CBD area, the overall significance of the negative impacts will remain moderate. Significance Statement for areas along the Toll road



Risk or Likelihood

Total Score


Proposed Route- Before Mitigation

Construction Short Term 1 Localised 1 Moderate 2 Prob 3 7 LOW-

Operation Perm 4 Localised 1 Slight 1 Prob 4 9 MODERATE - Proposed Route- After Mitigation

Construction Short Term 1 Localised 1 Slight 1 Prob 3 6 LOW -

Operation Perm 4 Localised 1 Slight 1 Prob 3 9 MODERATE - Short Route- Before Mitigation

Construction Short Term 1 Localised 1 Moderate 2 Prob 3 7 LOW -

Operation Perm 4 Localised 1 Slight 1 Prob 4 9 MODERATE - Short Route- After Mitigation

Construction Short Term 1 Localised 1 Slight 1 Prob 3 6 LOW-

Operation Perm 4 Localised 1 Slight 1 Prob 3 9 MODERATE - No Toll Highway- Before Mitigation

Operation NA NA NA NA NA No Toll Highway- After Mitigation

Operation NA NA NA NA NA Significance Statement for CBD Areas



Risk or Likelihood

Total Score


Proposed Route- Before Mitigation Construction NA NA NA NA NA

Operation Perm 4 Localised 1 Slight Beneficial 1 May

Occur 2 8 MODERATE BENEFICIAL







9.2.5 Impact 6: Increased HIV/AIDS and STD risks associated with construction gangs

and increased truck traffic Description of impact: Construction activities can have a negative impact on local communities through the impact of an influx of construction workers and the potential spread of HIV/AIDS and STDs. However, the potential impact during the construction phase is negligible. Potentially more of a problem is an increase in truck traffic. This risk is of concern as it has been well documented for some time now that long distance truck drivers are associated with the spread of HIV/AIDS (see for instance Alam, undated; Kulis, undated; United Nations, 2007). The risk, although potentially a consequence of the road is not directly related to the SANRAL initiative as the road is already a major trucking route. Mitigation objective: To reduce the risk of the spread of HIV/AIDS and STDs. Mitigation measures:

• The Contractor should, in consultation with local HIV/AIDS organisations and government structures, design and implement an HIV/AIDS and STD awareness and prevention campaign. This campaign should use various common practice methodologies in order to ensure social and cultural sensitivity.

• The Contractor must ensure that job opportunities available to local people who do not need to be housed in construction accommodation are maximised.

• The Contractor should make HIV/AIDS and STD awareness and prevention programmes a condition of contract for all suppliers and sub-contractors.

• The Contractor should provide an adequate supply of free condoms to all workers. Condoms should be located in the bathrooms and other communal areas on the construction site.

• A voluntary counselling and testing programme should be introduced during the construction phase and continued during operations. This will be undertaken in conjunction with the existing VCT programmes.

• The Contractor should undertake a HIV/AIDS and STD prevalence survey amongst all workers on a regular basis. It will involve a voluntary test available to 100% of the workforce11. The results of the survey will help to determine the HIV/AIDS and STD strategy. When and if statistically representative results are obtained the results of the survey should be made available to management and workers at the same time. Results should be presented as statistical returns that ensure confidentiality.

During the operational phase

• The Operator should, in association with HIV/AIDS organisations and government structures, implement an HIV/AIDS and STD awareness and prevention campaign directed at local villages along the route. This will include information dissemination sessions within the villages and provision of pamphlets and condoms.

11 Voluntary samples are not necessarily statistically accurate as they are not strictly random.






No Toll Highway- Before Mitigation Operation Perm 4 Localised 1 Slight 1 Prob 3 9 MODERATE -

No Toll Highway- After Mitigation Operation Perm 4 Localised 1 Slight 1 Prob 3 9 MODERATE -



If the mitigation measures are successfully implemented then this impact will remain negative, but will be of low significance and low intensity. Assessment: The risk of the road contributing towards an increase in HIV/AIDS and STDs, particularly during the operational period of the project exists along this section of the route. Without mitigation: The impact is assessed with a medium level of confidence. It is anticipated that, during the construction phase without mitigation for both the Proposed and Short Routes, this impact is unlikely to occur over the short-term on a localised scale with moderate severity. The impact is negative with an overall significance of low. During the operation phase, for the Proposed Route and Short Route, the impact will probably and may occur respectively over the long-term on a localised scale with a moderate severity and an overall significance of moderate.. With mitigation: If the suggested mitigation measures are successfully implemented, then in the construction phase, although the overall significance of this negative impact would remain low, its severity would decrease from moderate to slight for both route options. With mitigation measures during the operation phase, the overall significance of this negative impact is likely to be decreased for both route options from moderate to low resulting from a decrease in the severity of the impact from moderate to slight. Significance Statement



Risk or Likelihood

Total Score



Construction Short Term 1 Localised 1 Mod 2 Unlikely 1 5 LOW -

Operation Long Term 3 Localised 1 Mod 2 Prob 3 9 MODERATE -

Proposed Route- After Mitigation

Construction Short Term 1 Localised 1 Slight 1 Unlikely 1 4 LOW -

Operation Long Term 3 Localised 1 Slight 1 May

Occur 2 7 LOW -

Short Route- Before Mitigation

Construction Short Term 1 Localised 1 Mod 2 Unlikely 1 5 LOW -

Operation Long Term 3 Localised 1 Mod 2 Prob 3 9 MODERATE -

Short Route- After Mitigation


Operation Long Term 3 Localised 1 Slight 1 May

Occur 2 7 LOW -

No Toll Highway- Before Mitigation Operation NA NA NA NA NA

No Toll Highway- After Mitigation Operation NA NA NA NA NA 9.2.6 Impact 7: Secondary effects such as potential increased crime Description of impact: Several interest groups indicated that they considered that an increase in criminal activity due to an influx of workers during the construction phase and greater access during the operational phase was likely. This is not to suggest that construction workers are criminals but that increased mobility leads to increased “cover” for criminal elements.



Mitigation objective: To reduce the risks of crime. Mitigation measures:

• Established liaison structures with local police to monitor changes during the construction phase;

• Where necessary additional security should be provided; • South African legislation makes allowance for the establishment of Community Policing

Forums. Where they do not exist in the affected areas the Contractor should assist with facilitating the establishment of these forums.

Assessment: The introduction of strangers, sometimes indistinguishable from construction workers, has the potential to break down local internal policing strategies and potentially lead to an increase in crime. Increased access also has the possibility of increasing crime levels. As such there is a potential operational risk as well. Without mitigation: This impact is assessed with a medium level of confidence. In the construction phase, this impact may occur over the short-term on a localised scale for both the Proposed and Short Routes. However, the severity of this negative impact for the Proposed Route would be moderate with an overall significance of low and for the Short Route the impact would be slightly severe with a low overall significance. During the operation phase for both route options, the impact may occur permanently over a localised scale with a moderate severity. This impact will be negative with an overall significance that is moderate. With mitigation: If the suggested mitigation measures are successfully implemented, then for both the construction and operation phases for both route options, then although this negative impact will retain an overall significance of low and moderate respectively, the severity of the impact is likely to decrease from moderate to slight for construction of the Proposed Route and from moderate to slight during operation of the short route. Although this does not alter the score greatly, mitigation should be pursued nevertheless. Significance Statement



Risk or Likelihood

Total Score



Construction Short Term 1 Localised 1 Moderate 2 May

Occur 2 6 LOW -

Operation Perm 4 Localised 1 Moderate 2 May Occur 2 10 MODERATE -


Construction Short Term 1 Localised 1 Slight 1 May

Occur 1 5 LOW -

Operation Perm 4 Localised 1 Slight 1 May Occur 2 9 MODERATE -


Construction Short Term 1 Localised 1 Slight 2 May

Occur 2 6 LOW -

Operation Perm 4 Localised 1 Moderate 1 May Occur 2 10 MODERATE -



Operation Perm 4 Localised 1 Slight 1 May Occur 2 9 MODERATE -


No Toll Highway- After Mitigation Operation NA NA NA NA NA



9.2.7 Impact 8: Resettlement of affected households Description of impact: The construction of a new road in the Concordia area where large numbers of people are living illegally on the existing road reserve, will require that these households be resettled. The numbers of people to be resettled in this area is in dispute but it is estimate that somewhere between 250 and 1000 households will be required to move. There will also be 5-10 forestry worker households and a school that may need to be resettled to develop the Brackenhill interchange for the Proposed Route, unless the road can be realigned. International experience shows that, unless the best practice benchmarks are achieved, resettlement exposes affected people to a range of risks such as:

• landlessness • homelessness • joblessness • economic and social marginalization • increased morbidity and mortality • food insecurity • loss of access to common property resources • social and cultural disarticulation/disruption

In this regard poorer households are at particular risk. Mitigation objective: Provide an acceptable alternate resource for those affected by the loss. Mitigation measures: Resettlement must be conducted in terms of international best practice and accompanied by a comprehensive resettlement action plan. This goes further than merely fulfilling the legislative requirements of compensation. According to the World Bank's Revised Policy on Involuntary Resettlement (OP/BP 4.12) (2006), best practices must ensure that:

• Involuntary resettlement should be avoided, or minimised where unavoidable. • Where resettlement is unavoidable, resettlement plans and activities should be seen and

executed as development programmes. • Resettled persons should be provided with sufficient investment resources and

opportunities to share in project benefits. • Displaced persons should be meaningfully consulted, and should participate in the planning

and implementation of resettlement programmes. • Displaced persons should be compensated, prior to the move, for their losses at full

replacement cost. • Resettled persons should be assisted with the move and provided with support during the

transition period. • Resettled persons should be assisted with their efforts to improve, or at least restore, their

former living standards, income earning capacity and production levels – whichever is higher.

Assessment: It is evident that a large number of households will need to be resettled in order to make way for the highway. This is one of the impacts of greatest concern. The No Toll Highway option could avoid this resettlement impact in the short term, but if it cannot relieve the traffic congestion for long, and highway will still need to be developed some time in the future. Without mitigation: This impact is assessed with a high level of confidence. It is anticipated that for the construction phase, for both the Proposed and Short Route options, this impact will definitely occur in the short-term on a localised scale. The impact will be negative with and very severe in ths case of the proposed route and severe for the short route. For both route options however, the overall significance of this impact will be high.



With mitigation: If the suggested mitigation measures are successfully implemented, then although it is unlikely, during the construction phase although the impact remains negative for both route options, the severity of the impact is lowered from very severe to moderate for the proposed route and from severe to moderate for the short route with the overall significance of this impact decreasing from high to low for both route options. Significance Statement



Risk or Likelihood

Total Score



Construction Short Term 1 Localised 1 Very

Severe 8 Definite 4 14 HIGH -

Operation NA NA NA NA NA Proposed Route- After Mitigation

Construction Short Term 1 Localised 1 Moderate 2 Unlikely 1 5 LOW -

Operation NA NA NA NA NA Short Route- Before Mitigation

Construction Short Term 1 Localised 1 Severe 8 Definite 4 14 HIGH -

Operation NA NA NA NA NA Short Route- After Mitigation

Construction Short Term 1 Localised 1 Moderate 2 Unlikely 1 5 LOW -

Operation NA NA NA NA NA No Toll Highway- Before Mitigation

Operation NA NA NA NA NA No Toll Highway- After Mitigation

Operation NA NA NA NA NA 9.2.8 Impact 9: Loss of access to natural capital Description of Impact: Some of the stakeholders felt that the construction of the Toll Highway would sever people from the access to resources such as grazing and forest resources. This is relevant for the disadvantaged residents living adjacent to the road reserve in the Concordia area. Mitigation objective: Where access to grazing and forest resources is a legal entitlement then mitigation in the form of restored access should be designed. Mitigation measures: Design of appropriate numbers of under or overpasses so that access from resources is not impeded Assessment: Within the context of rural and peri-urban poverty access to natural capital is often of critical importance for household survival. There is no impact for the “No Toll Highway” option. Without mitigation: This impact is assessed with a medium level of confidence. During the construction phase for both the Proposed and Short Routes, the impact is unlikely to occur over the short term on a localised scale with a slight severity. The overall significance of this impact will be low. For the operation phase for both routes, the impact will probably occur over the long term on a localised scale with a slight severity and an overall significance of moderate.



With mitigation: If the suggested mitigation measures are successfully implemented, then although it is unlikely that the impact will occur during the construction phase, the impact remains negative for both route options, and the overall significance low. During the opration phase however, for both route options, the likelihood of the impact occurring changes from probable to unlikely, with an associated decrease in the overall significance from moderate to low. Therefore, although mitigation measures will reduce likelihood of the impact occurring as well as its significance from probably to unlikely and moderate to low respectively for both route options in the operational phase but have little impact in the construction phase the mitigation measures should be pursued nevertheless. Significance Statement



Risk or Likelihood

Total Score




Operation Long Term 3 Localised 1 Slight 1 Probable 3 8 MODERATE -



Operation Long Term 3 Localised 1 Slight 1 Unlikely 1 6 LOW -



Operation Long Term 3 Localised 1 Slight 1 Probable 3 8 MODERATE -



Operation Long Term 3 Localised 1 Slight 1 Unlikely 1 6 LOW -


No Toll Highway- After Mitigation Operation NA NA NA NA NA 9.2.9 Discussion This section provides further contextualisation and discussion around the issues that have been identified in the impact assessment above as those requiring the most critical management intervention and adoption of mitigation strategies. As such it selects only the most critical items for further consideration or those under which the developer can be expected to make a meaningful difference through the introduction of relevant mitigation strategies. Resettlement and compensation One of the most critical aspects of the project is likely to be the need to resettle people out of the informal settlements within the road reserve for the Toll Highway. In this regard it is imperative that the project develop, at the very least, a Resettlement Policy Framework (RPF). This should be in line with international best practice and should go beyond discussions of asset acquisition and compensation. The RPF should be put in place to ensure that the resettlement process does not expose affected people to unnecessary risks. The range of risks associated with resettlement are usually categorised as:



• landlessness • homelessness • joblessness • economic and social marginalization • increased morbidity and mortality • food insecurity • loss of access to common property resources • social and cultural disarticulation/disruption.

All of these must be kept in mind by the developers who must make every effort to ensure that these risks are kept to a minimum for all effected communities living along the Proposed Route. Some issues that complicate the resettlement process and need to be considered, discussed and resolved by all the key stakeholders, and should probably be mentioned in the EIA:

• How to resolve the issue of creating an incentive for people to illegally squat on the road reserve, especially since not all of the road reserve will be used for the highway and the unused land may be occupied again?

• Should the needs of the ‘illegal squatters’ be prioritised above those who have been in Knysna for a long time, have had their name on the housing list for a long time, and been doing the right thing by not squatting illegally on the road reserve? The resettlement of these illegal squatters into other areas to be developed for housing has the effect of reducing the opportunity for other informal dwellers in townships. This is essentially an impact on the host communities that needs to be mitigated.

• Should the illegal squatters be given houses, or just sites and assistance with moving their dwellings (most if not all of which are movable)?

• If they are given houses, services and other assistance then this will create an incentive for other people to occupy the remaining road reserve once the highway is built. The municipality will then have to move more people in the future when the other half of the highway is built.

• If future illegal squatting cannot be prevented, should those illegally squatting on that part of the road reserve that will not be used by the current highway proposal, be left there and informed that they will not receive assistance with services and will be removed when the highway is expanded in the future, in order to create an incentive for people to look for better and more secure alternative accommodation. This would be one way in which resettlement could be minimized as per World Bank guidelines.

Labour issues It is clear from the discussion under Section 12.3 in Specialist Volume Part 2 that unemployment levels in the Knysna area are high. At these levels there is little doubt that the area is in desperate need of job creation initiatives and the project has the potential to assist in this regard. However, it must be realised that the creation of jobs is not a straightforward matter and there is some discussion as to how best to ensure that job creation is managed within the context of maximising equity returns and local involvement In terms of employment it is envisaged the following jobs will be created over a period of about three years.:

1. Supervision Team from the Consultant • Project Engineer • Resident Engineer and assistant Resident Engineer • Earthworks and Bridges Clerks of Works • 2 senior material technicians and 1 laboratory manager • 6 junior laboratory technicians / staff

2. Contractor’s Team



• Project Manager • Senior Site Agent • 2 junior Site Agents • Senior Earthworks and Bridge Foremen • Quarry Manager • 4 Junior Foremen • 2 materials technicians • 2 Surveyors • Safety Officer • 20 plant operators • 30 drivers • 30 skilled labourers • 100 unskilled labourers

On a social level the issue of job creation is often associated with the reservation of employment opportunities. Job reservation appears to be of concern to many of the potentially affected people, and the negative impact associated with potential increases in social tensions that this brings has been mentioned above. In order to ensure that the positive impacts are maximised at the local/sub-regional level, and in order to obviate some of the negative impacts alluded to in the section above, it is strongly recommended that as many employment opportunities as is practical are reserved for local people. Reserving employment for local people has been done successfully in many projects in many parts of the world and is particularly successful within conservational circles in an effort to gain local support (Sekhar, 2003) Although there are no rigid legislative parameters that force developers to use local communities in actively developing local employment strategies there is a move towards what might best be termed as ‘responsible best practice’. In the context of the proposed Knysna Toll Road (or No Toll Highway option) it is suggested that four elements of this responsible best practice need to be incorporated into overall project design, construction and employment policy. These are: • involvement by local Department of Labour authorities • Involvement of the Municipality • design of contractor tender requirements • SMMEs • training This is in accordance with SANRAL’s stated policy on training, job creation and small business development where it is indicated that ‘[t]he ethos of the Agency’s targeted procurement philosophy is that we can and are contributing to economic growth in our country and the Southern African region as a whole by training people to become economically active and by reducing unemployment and by stimulating growth in the small and informal sector of our economy’ (SANRAL, 2004:40). The enactment of this policy is crucial to the success of the Project. SANRAL also embeds targeted employment into its tender procedure. Furthermore, in this regard the Department of Labour has recently embarked on a more pro-active approach towards employment creation12. One of the mechanisms by which the department has been committed to ensuring that proactive engagement with developers occurs, in an effort to deal with the issue of poverty, is through maintaining a database of people seeking work and the skills that they have to offer.

12 See ‘Creating Jobs, Fighting Poverty: An Employment Strategy Framework’ (2004) (http://www.labour.gov.za/docs/policy/jobsframework.html.)



Although the quality of the various data bases available in the regional offices of the Department of Labour has not been empirically tested for the purposes of this project there is an assurance that such data is available in Knysna. It is important that the Contractor forms a positive relationship with these offices and uses this data as a basis on which to recruit local labour as construction progresses along the route. For the purposes of this project it is suggested that the developer stipulate that all contractors during the construction phase as well as the highway operators be required, as far as possible, to utilise the Department of Labour as its primary source of labour recruitment. Furthermore, unlike Tender documents in the public sector, the private sector has a great deal more flexibility in terms of its tender procedures. Although public sector procurement policies have not yet developed to stipulate maximisation of local employment opportunities there are a number of ‘best practice’ guidelines that have been developed and that are frequently utilised as instructions in tender documents. In essence four elements have been developed in this regard. These are: • Where possible labour-intensive methods of construction should be utilised. While this is often

regarded as a desirable goal it is acknowledged that this may not be entirely practical within the context of a private sector set of tender requirements. Nevertheless it is recommended that the developer, in conjunction with their professional service providers, examine means by which this could become a tender instruction in relevant contracts.

• Use local labour as far as possible. The developer and its contractors should recruit and employ staff in an equitable and transparent manner and maximise the proportion of staff employed from the local community. The developer should set targets for increasing the proportion of staff and/or of the enterprise wage bill going to communities within 10 km of the enterprise.13 It should be noted that by using a local labour strategy some of the concerns around the spread of HIV/AIDS and STDs and other negative aspects attached to in-migration are significantly reduced.

• Develop a community labour agreement with targets for employment and for progression. Recognise that the enterprise can play a significant role in increasing the skills and capacity of the local community and that the enterprise benefits from that.14 In this regard it is recommended that the developer formalise labour agreements, with the assistance of the Department of Labour, with the affected communities – these should be geographically defined for the various contractors.

• Go beyond the bare minimum wage rate and invest in local staff – quality is dependent upon well-motivated staff.15

Further it is recommended that the developer actively work towards facilitating access to Basic Skills Training. The intention behind this is ‘skill up’ local workers employed on the development to perform the tasks required of them during the contract and, in the post-construction phase, to be able to sustain a level of income through selling these skills either in the labour market or as local contractors. The establishment of a training and skills development programme would therefore be a key component of the overall employment strategy. The broad elements of such a programme could be drafted by the developer but individual successful contractors will have to draft a more detailed training programme and also take responsibility for implementation. Such a programme should be guided by a number of principles and features: • All the major construction work components of the project should be accompanied by the

identification of the broad number, categories and types of job opportunities needed.

13 See Appendix B ‘National Responsible Tourism Guidelines’ DEAT 2002 14 Ibid 15 Ibid



• A wide range of training opportunities and services must be identified within the overall cost structure of the project. This should range from simple job application procedures and pre-tender information sessions, to on-site technical training and mentorship. Contractors would show how they would gear-in funds; perhaps out of Skills Development Levy coffers for such programmes. This would be used to demonstrate how they would offset the costs that they might otherwise incur and pass on to the developer.

• The scope and content of the training programme must be clearly outlined by the contractor. The nature of this programme must be explicitly linked to the project tasks and as far as possible to the individual’s career plan.

• The responsibility for implementing the training programme might rest with the contractor. However the contractor should operate the programme under the advice of the developer and he should ensure that the programme is in harmony with the overall employment guidelines set up by the developer.

• The ‘community labour desk’ must ensure that the needs of all the various parties and interests are dealt with fairly and that this occurs within the overall programme and budget of the projects.

The number of permanent and sustainable jobs directly created by the Toll Road is likely to be limited and substantially less than those jobs created during the construction phase. Nevertheless the developer can make some contribution towards ensuring that the road acts to bolster local employment and skills development in accordance with SANRAL’s stated intent16. In this regard it is recommended that the developer generate a policy for small, medium and micro-enterprises and that the various policies and positions developed by the Department of Trade and Industry be adhered to.17 Health Projects Although it is not SANRAL’s responsibility to promote health infrastructure along the route, the reputation of SANRAL and the project will be greatly benefited should SANRAL become involved in health infrastructural development as it pertains to transport issues. Potentially an effective ambulance service could be installed to service areas hitherto poorly serviced. It might be argued that a critical issue is that resettled households should be given priority in being incorporated into empowerment projects, with particular focus given to vulnerable households. Resettled households will be the most affected by the toll road, and therefore should be first in line for any benefits accruing. A counter argument is that this merely increases the incentive to illegal squatting. SANRAL has already indicated that South African legislation does not allow local communities to be stakeholders in the toll plazas (CCA, 2007).18 However, there is no law against local people and businesses investing in the project and becoming part owners. Road safety education Although potentially not a very serious impact there is a school of thought that believes that all new road projects should be accompanied by educative projects. As such a road safety education plan, in accordance with SANRAL’s declaration of intent (SANRAL, 2005: 62) would need to be put into place. It would also be important to provide sufficient and well maintained cordoning off of the road and its margins, so as to ensure that that highway is a ‘limited access highway’ and to mitigate against the risk of accidents. Sufficient and easily accessible crossing points – bridges and

16 See South African Road Agency Limited Declaration of Intent 2005–2008. 17 See Berry et al. (2002). The Economics of SMMES in South Africa. 18 Proposed N2 Wild Coast Toll Highway: Final Scoping Report – Comments and Responses Report on DSR



underpasses that permit more than just pedestrians – would also need to be put in the right places.19 These crossings would greatly diminish the possibilities of accidents involving pedestrians and/or livestock occurring. Road safety programmes would need to concentrate on children in schools, with lessons taught on how to deal with the road safety and specifically to the N2. Community meetings and safety presentations would also need to put into place to inform communities of the risks of the road, and how to minimise these risks. Virtual demonstrations presented in education workshops of the dangers would go some way towards lessening the chances of accidents involving pedestrians and livestock. Given that this education would need to be ongoing it would be appropriate to develop video/DVD material in the local languages that could be used by the schools and other civic organisations on an ongoing basis. National road safety adverts/educational inserts would also be appropriate. Infrastructure would need to be put in place so as to complement any road safety programme. Designated pedestrian walkways running along sections of the road would also minimise the chances of pedestrians attempting to use the road and thereby of accidents occurring. Elevated lighting of the road and its margins through some of the populated rural areas will also need to be installed so as to minimise the chances of accidents. ‘Do Nothing option’ The ‘Do Nothing option’ is perhaps the most difficult to assess. This is the ‘benchmark option’ against which the proactive options are assessed and costed. In current international management practice the ‘do nothing option’ is sometimes viewed as the most expensive solution as the costs of long-term impacts on no action often outweigh the proactive implementation costs and can therefore be easily dismissed. In a situation where a resource is clearly under pressure and demands are growing, the ‘do nothing option’ is usually not feasible unless the strategy is to impose punitive measures by effectively crippling the resource. In a situation where a proactive alternative is mooted to expand economic growth or forestall a potential future problem, as has been argued is the case for the Knysna Toll Highway, then the ‘do nothing option’ often has at least merit as a benchmark. The traffic and economic impact assessments for this Knysna highway project support this argument. The ‘do nothing option’, at least in the short term would:

• Have a limited impact on people living in the reserve of the proposed Toll Highway. • Would have some positive impacts attached to the maintenance of the status quo but also

some negative impacts associated with access to health services and job opportunities. • Could impact on the economy of Knysna as a tourist destination • Would place the existing road resources under increasing pressure.

9.2.10 Conclusions from the Social Analysis Of the nine social impacts identified (see Table 9.1) and associated with the proposed and Short Routes

• One is a moderately positive impact. • Eight are negative impacts. Prior to mitigation there are five impacts that are assessed as

largely moderate and two as largely high. Two of the moderate negative impacts are also positive impacts for some residents. After mitigation none of the impacts remain high. After mitigation there are five impacts that are reduced to or remain moderate, two impacts that are reduced to low.

In comparison, the Do Nothing has three high negative impacts, one of which cannot be effectively mitigated. 19 The Taxi industry should be involved in these discussions. Ad Hoc taxi pick up and drop off points are a major road hazard.



Table 9.1: Summary of the Social Impacts for the different alternatives Impact Alternatives Without Mitigation With Mitigation

Proposed Highway HIGH - MODERATE - Short highway HIGH - MODERATE - Impact 1: Increased cost of doing business and

concomitant loss of income Do nothing option HIGH - N/A Proposed Highway HIGH - MODERATE - Short highway HIGH - MODERATE - Impact 2: Increased cost of accessing services

and employment for marginal communities Do nothing option HIGH - N/A Proposed Highway MODERATE - MODERATE - Short highway MODERATE - MODERATE - Impact 3: Increased cost of accessing services

and employment for advantaged communities Do nothing option HIGH - HIGH - Proposed Highway MODERATE - MODERATE - Short highway MODERATE - MODERATE - Impact 4: Increased pollutants along the toll

road area Do nothing option N/A N/A Proposed Highway MODERATE - MODERATE - Short highway MODERATE - MODERATE - Impact 5: Increased pollutants in the CBD area Do nothing option MODERATE - MODERATE - Proposed Highway MODERATE - LOW - Short highway MODERATE - LOW -

Impact 6: Impact HIV/AIDS and STD risks associated with construction gangs and increased truck traffic Do nothing option N/A N/A

Proposed Highway MODERATE - MODERATE - Short highway MODERATE - MODERATE - Impact 7: Increased crime levels Do nothing option N/A N/A Proposed Highway N/A N/A Short highway N/A N/A Impact 8: Resettlement of affected households Do nothing option N/A N/A Proposed Highway MODERATE - LOW - Short highway MODERATE - LOW - Impact 9: Loss of access to Natural Capital Do nothing option N/A N/A

The potential severity of each of these negative impacts for those who face relocation, a disruption in livelihood or the loss of a job cannot, however, be overestimated and this is important for the developers to note. Given that there are some important social costs associated with the Do Nothing option, some social benefits of the highway for the CBD area and some negative impacts which can, if mitigated as suggested, limit the impacts to low or moderate levels. Issues around resettlement, effective urban planning, and access control, and concessions for users will however need to be adequately managed. These will form the cornerstones of any mitigation strategy. In terms of the social impacts of the two routes, there is little to choose. However, taking into consideration some of the economic and other non-social impacts which have social consequences, the conclusion is that the Proposed Route would be marginally more attractive than the Short Route in the medium term. In terms of the major access points to the CBD, the Eastford Interchange would probably be marginally less acceptable than the Salt River Interchange. There are currently a number of developments taking place in the Eastford area at the moment and along its associated link road. There are also adjacent developments in the Salt river area but probably less. The noise associated with the Salt River interchange would probably be greater. There are safety risks associated with both options. The Salt River interchange is likely to be more visually intrusive. Additional land would be required for both interchanges. Salt River would however probably be a shorter route into town. However with sufficient mitigation both interchanges are acceptable.



From a social perspective it can be concluded that although there are a number of negative social impacts that are typically associated with Toll Road development (Proposed and Short Routes), these impacts, to a greater extent, can be mitigated. While the “do nothing” appears to have fewer negative social impacts and as such appears to be a viable option from the perspective of the social impact assessment, it has no highly beneficial impacts. However, some of the economic, noise, visual and traffic related impacts have important social consequences which make this option less acceptable. 9.3 Heritage Impacts This study examined the impacts of the two route alternatives (Proposed and Short), the Do Nothing option and the ‘Do Minimum’ option. The inclusion of the ‘Do Minimum’ option in this study arose from the potential impacts it might have on some heritage resources in the Knysna CBD. This study identified nine potential heritage impacts (see Table 9.2 for a summary of these impacts):

1. Places, buildings structures and equipment 2. Places to which oral traditions are attached or area associated with living heritage 3. Historical settlements and townscapes 4. Geological sites of scientific or cultural importance 5. Archaeological and palaeontological sites 6. Graves and burial grounds 7. Sites of significance to the history of slavery in South Africa 8. Movable objects excluding any object made by a living person

9.3.1 Places, buildings, structures and equipment Cause and comment Most, if not all, of the buildings in these urban residential areas are affected indirectly by the ‘Proposed’ and ‘Short’ routes are younger than sixty years, and do not constitute heritage resources of significance. There are also a large (as yet uncounted) number of households living on the proclaimed road reserve, comprising informal residences (see below). These structures and buildings will be directly affected by the ‘Proposed’ and ‘Short’ routes, since they will be demolished. However, none of these structures constitutes heritage resources older than sixty years, or with other heritage significance, and may therefore be altered or demolished with no permit from Heritage Western Cape. The effects of the ‘Do Nothing’ and ‘Do Minimum’ routes would be limited to the Knysna CBD. While the ‘Do Nothing’ option would not directly impact any buildings or structures older than sixty years, the ‘Do Minimum’ route would directly and indirectly affect numerous places, buildings and structures older than sixty years. These heritage resources have various levels of significance for their historic, aesthetic, social, spiritual and cultural values. A permit from Heritage Western Cape would be required for any alteration to them. An architectural impact assessment should identify all heritage resources in this category affected directly and indirectly and propose appropriate mitigation measures. Provincial Heritage Sites are proclaimed and protected in terms of Section 27 of the Heritage Resources Management Act of 1999, and comprise places with special qualities that make them significant in the context of the province or a region. No person may destroy, damage, deface, excavate, alter, remove from its original position, subdivide or change the planning status of any such heritage site without a permit issued by Heritage Western Cape. In the case of the ‘Do Nothing’ case, impacts on heritage resources will not be direct but would probably indirectly affect the character of the CBD. Impacts on heritage resources in this case will be negative, with a slight to moderate severity and significance over the medium to long term and may occur. This impact is assessed with a medium to high level of confidence (see Table 9.2).



In the case of the ‘Do Minimum’ route, impacts on heritage resources in this category will be negative, with a medium to high intensity and significance and will highly probably or definitely occur. This impact is assessed with a medium to high level of confidence. Mitigation measures ‘Proposed’ and ‘Short’ routes – Not applicable The only mitigation appropriate for the ‘Do Nothing’ option is to implement one of the alternative routes. ‘Do Minimum’ route –A permit from Heritage Western Cape is required to alter any structure older than sixty years in any way. Significance Statement



Risk or Likelihood

Total Score


Proposed Route - Before Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA Proposed Route - After Mitigation

Construction NA NA NA NA NA Operation NA NA NA NA NA

Short Route - Before Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA Short Route – After Mitigation


Do Minimum Option – Before Mitigation Construction Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH -

Operation Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH - Do Minimum Option – After Mitigation

Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE- Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Do Nothing option - Before Mitigation Construction N/A N/A N/A N/A N/A

Operation Medium term 2 Localised 1 Slightly

severe 1 May occur 2 6 LOW -

Do Nothing option – After Mitigation Construction N/A N/A N/A N/A N/A

Operation N/A N/A N/A N/A N/A



9.3.2 Places to which oral traditions are attached or which are associated with living heritage

Cause and comment ‘There are a large (as yet uncounted) number of households living on the proclaimed road reserve. These people will be directly affected as they will have to be relocated if the proposed toll highway is to go ahead along the proclaimed reserve. In general, these residents do not appear to have a serious objection to the idea of relocating from the area as long as they are properly consulted and alternative sites and accommodation is provided as well as assistance with moving. They did, however, raise concerns about problematic negotiation processes in the past and the lack of delivery on compensation issues. As a result of this, people have doubts about the current process and are concerned about whether housing and services will be provided. Although we were not able to gain direct access to households living within the proclaimed road reserve, we have studied the Social Impact Assessment prepared for this project and consider that it is very unlikely that significant heritage resources in this category will be affected by the ‘Proposed’ and ‘Short’ routes. The effects of the ‘Do Nothing’ route would be limited to the Knysna CBD, indirectly affecting various places to which oral traditions are attached or which are associated with living heritage, such as churches and market places. The effects of the ‘Do Minimum’ route would be limited to the Knysna CBD, directly and indirectly affecting various places along Gordon Street and other areas that may need to be acquired and transformed to construct a new one way street parallel to waterfront drive, to which oral traditions may be attached or which are associated with living heritage, such as churches and market places. Mitigation objective To limit or eliminate direct and indirect impacts on places to which oral traditions are attached or which are associated with living heritage. Mitigation measures ‘Proposed’ and ‘Short’ routes – Not applicable; no heritage resources in this category will be affected directly. ‘Do Nothing’ route – the only mitigation is to adopt one of the other alternatives. ‘Do Minimum’ route – Architectural and historical impact assessments should identify all heritage resources in this category affected directly and indirectly and propose appropriate mitigation measures. Assessment The ‘Proposed’ and ‘Short’ routes are both preferable to the ‘Do Nothing’ and ‘Do Minimum’ options. Without mitigation: No heritage resources in this category will be affected directly by the ‘Proposed’ and ‘Short’ routes. In the case of the ‘Do Nothing’ route, impacts on heritage resources in this category will be negative, with a slight to moderate severity and significance and may occur. This impact is assessed with a medium to high level of confidence.



In the case of the ‘Do Minimum’ route, impacts on heritage resources in this category will be negative, with a moderate to high severity and significance over a permanent timeframe and will highly probably or definitely occur. This impact is assessed with a medium to high level of confidence. With mitigation: No heritage resources in this category will be affected directly by the ‘Proposed’ and ‘Short’ routes. In the case of the ‘Do Minimum’ route, impacts on heritage resources in this category will be neutral to negative, with a low to medium intensity and significance and will probably or highly probably occur. This impact is assessed with a medium to high level of confidence. In the case of the ‘Do Nothing’ route, impacts on heritage resources in this category will be neutral to negative, with a slight severity and significance and may occur. This impact is assessed with a medium to high level of confidence. Significance Statement



Risk or Likelihood

Total Score





Short Route - Before Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA Short Route – After Mitigation


Do Minimum option - Before Mitigation Construction Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH -

Operation Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH - Do Minimum option – After Mitigation

Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE - Operation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE -

Do Nothing option - Before Mitigation Construction NA 0 NA 0 NA 0 NA 0 0 N/A

Operation Medium 2 Localised 1 Moderate 2 May Occur 2 7 LOW -

Do Nothing option – After Mitigation Construction NA 0 NA 0 NA 0 NA 0 0 N/A

Operation Medium 2 Localised 1 Slight 1 May Occur 2 6 LOW -

9.3.3 Historical settlements and townscapes Cause and comment Direct effects of the ‘Proposed’ and ‘Short’ routes on the historical townscape of Knysna will be minimal, whereas indirect effects (improved traffic flow, less heavy vehicular traffic) could be considered positive.



The effects of the ‘Do Minimum’ route would be limited to the Knysna CBD, directly and indirectly affecting Knysna’s historical townscape. The sense of place of the CBD would be altered significantly and permanently. The effects of the ‘Do Nothing’ route would be limited to the Knysna CBD, indirectly affecting Knysna’s historical townscape. The sense of place of the CBD would be compromised significantly over the short to medium (until such time something is done to address the traffic problems). Mitigation measures ‘Proposed’ and ‘Short’ routes – Not applicable; this heritage resource category will not be affected directly. ‘Do Minimum’ route – An appropriately qualified specialist should undertake an assessment of the historical townscape of Knysna to determine whether effective implementation of the ‘Do Minimum’ route could limit or eliminate direct and indirect impacts on this heritage resource category. ‘Do Nothing’ route – the only appropriate mitigation measure would be one of the alternative route options. Assessment The ‘Proposed’ and ‘Short’ routes are both preferable to the ‘Do Minimum’ and ‘Do Nothing’ options. Without mitigation: No heritage resources in this category will be affected directly by the ‘Proposed’ and ‘Short’ routes. In the case of the ‘Do Minimum’ route, impacts on heritage resources in this category will be negative, with a medium to high intensity and significance and will definitely occur. This impact is assessed with a high level of confidence. In the case of the ‘Do Nothing’ route, impacts on heritage resources in this category will be negative, with a slight to medium intensity and significance and may occur over the short-medium term. This impact is assessed with a high level of confidence. With mitigation: No heritage resources in this category will be affected directly by the ‘Proposed’ and ‘Short’ routes. In the case of the ‘Do Minimum’ route, impacts on heritage resources in this category will be neutral to negative, with a medium intensity and significance and will highly probably occur. This impact is assessed with a medium to high level of confidence. In the case of the ‘Do Nothing’ route, impacts on heritage resources in this category will be negative, with a slight intensity and significance and may occur over the short-medium term. This impact is assessed with a high level of confidence. Significance Statement



Risk or Likelihood

Total Score





Short Route - Before Mitigation





Risk or Likelihood

Total Score



Short Route – After Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA Do Minimum option - Before Mitigation

Construction Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH - Operation Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH -

Do Minimum option – After Mitigation Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE - Do Nothing Option – Before Mitigation

Construction NA 0 NA 0 NA 0 NA 0 0 N/A

Operation Medium 2 Localised 1 Moderate 2 May Occur 2 7 LOW -

Do Nothing Option – After Mitigation Construction NA 0 NA 0 NA 0 NA 0 0 N/A

Operation Medium 2 Localised 1 Slight 1 May Occur 2 6 LOW -

9.3.4 Geological sites of scientific or cultural importance Cause and comment As indicated in the description of the geological environment provided in section 8.3.3 of the Specialist Volume Part 1, the landscape within the Knysna Basin is complex and can be considered one with a high sensitivity. This implies that the landscape has the potential for rapid and often irreversible change. Such change is often initiated by cumulative human impacts and can be triggered by meteorological events. Although no specific geological sites of scientific or cultural importance occur in the project area, the ‘Proposed’ and ‘Short’ routes could directly and indirectly affect sectors 2 and 3 of this sensitive geological landscape. Given the greater length of the ‘Proposed’ route the impact of this route is likely to be greater than that of the ‘Short’ route. In the case of the ‘Proposed’ routes impacts would be neutral to negative, with a severe intensity and high significance and will probably occur. This impact is assessed with a medium level of confidence. In the case of the ‘Short’ routes impacts would be neutral to negative, with a moderate intensity and significance and will probably occur. This impact is assessed with a medium level of confidence. Given the highly modified urban landscape in which the ‘Do Minimum’ and ‘Do Nothing’ routes will be implemented, it is highly unlikely that any geological sites of scientific or cultural importance would be affected by these routes option. In terms of impacts on geological features, the ‘Do Minimum’ and ‘Do Nothing’ option is preferable to the ‘Proposed’ and ‘Short’ routes. Mitigation measures ‘Proposed’ and ‘Short’ routes – The recommendations of the Erosion Impact Assessment for this project to limit direct and indirect impacts on sensitive geological features should be implemented.



‘Do Nothing’ route – Not applicable Significance Statement

Effect Phase Temporal Scale Spatial Scale Severity of

Impact

Risk or Likelihood

Total Score


Proposed Route - Before Mitigation Construction Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH -

Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Proposed Route - After Mitigation

Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE --

Operation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE -

Short Route - Before Mitigation

Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Short Route – After Mitigation

Construction Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE -

Operation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE -

Do Minimum option - Before Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA Do Minimum option – After Mitigation


Do Nothing option - Before Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA Do Nothing option - After Mitigation


9.3.5 Archaeological and palaeontological sites Cause and comment We accessed the site records of the Archaeological Data Recording Centre at the Iziko Museums of Cape Town on 5 June 2008. Only one site is recorded on the relevant 1:50 000 map sheet, 3423AA KNYSNA. This was a quartzite cobble Early Stone Age tool manufacturing site exposed during quarrying activities in the vicinity of the Harkerville Forest Station. The site was subsequently destroyed by expansions of the quarry in 1971. Washed quartzite cobbles are a feature of the basement deposits of the coastal plain, emanating from the intertidal zones of past raised sea levels. Accordingly, the potential for the occurrence of similar sites at the bases of valleys during road construction is high. The adjacent map sheet to the east, 3423 AB, records more than twenty archaeological sites. These span the Early, Middle and Later Stone Ages but are largely confined to the immediate coastal littoral where they occur as open air middens or cave deposits immediately along the foreshore (Robberg Peninsula, Matjes River etc.). The occurrence of this class of archaeological site is unlikely within or immediately adjacent to the road reserve, due to the nature of the topography and geology.



In summary, it is unlikely that significant archaeological or palaeontological sites will be affected by the ‘Proposed’, ‘Short’, and ‘Do Minimum’ Route options. The impact ratings in the table below are attributed with a medium to high level of confidence for these routes. As there would be no construction associated with the ‘Do Nothing’ route this impact is not applicable to this option. Mitigation measures ‘Proposed’, ‘Short’, and ‘Do Minimum’ routes – If any archaeological or palaeontological sites are encountered during construction, a permit from Heritage Western Cape will be required to alter these sites in any way. Depending on its significance, a heritage resource in this category might require detailed recording and / or excavation and curation of material in an approved heritage institution. ‘Do Nothing’ route – this impact does not apply. Significance Statement



Risk or Likelihood

Total Score


Proposed Route - Before Mitigation Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE - Proposed Route - After Mitigation

Construction Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE - Operation Permanent 4 Localised 1 Slight 1 Probable 3 9 MODERATE -

Short Route - Before Mitigation Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE - Short Route – After Mitigation


Do Minimum Highway option - Before Mitigation Construction Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE -

Operation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE - Do Minimum option – After Mitigation



Operation NA NA NA NA NA Do Nothing option – After Mitigation


9.3.6 Graves and burial grounds Cause and comment It is possible that ancestral graves are located within the proclaimed road reserve, associated with the informal settlement of households in these areas. Graves, both marked and unmarked, could also be located outside of proclaimed cemeteries elsewhere along the ‘Proposed’ and ‘Short’ routes. The significance of these impacts is provided in the table below and these impact ratings are attributed with a medium to high level of confidence.



Graves and burial grounds affected by the ‘Do Minimum’ route would be limited to proclaimed cemeteries within the Knysna CBD. If older than sixty years, such historical graves or cemeteries are protected in terms of the Heritage Resources Management Act of 1999. The significance of these impacts are provided in the table below and these impact ratings are attributed with a medium to high level of confidence. The ‘Do Nothing’ route would have no impact on graves and burial grounds. Mitigation measures ‘Proposed’, ‘Short’ and ‘Do Minimum’ routes – No graves or burial grounds may be altered in any way without the permission of the families concerned and a permit from Heritage Western Cape. Significance Statement



Risk or Likelihood

Total Score


Proposed Route - Before Mitigation Construction Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH -

Operation Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH - Proposed Route - After Mitigation

Construction Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH - Operation Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH -

Short Route - Before Mitigation Construction Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH -

Operation Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH - Short Route – After Mitigation

Construction Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH - Operation Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH -

Do Minimum option - Before Mitigation Construction Permanent 4 Localised 1 Moderate 2 Unlikely 1 8 MODERATE -

Operation Permanent 4 Localised 1 Moderate 2 Unlikely 1 8 MODERATE - Do Minimum option – After Mitigation-

Construction Permanent 4 Localised 1 Moderate 2 Unlikely 1 8 MODERATE - Operation Permanent 4 Localised 1 Moderate 2 Unlikely 1 8 MODERATE -


Operation NA NA NA NA NA Do Nothing option – After Mitigation


9.3.7 Sites of significance relating to the history of slavery in South Africa Cause and comment There are no records for sites of significance relating to the history of slavery in South Africa in and around Knysna. Accordingly, it is highly unlikely that any heritage resources in this category will be affected by any of the proposed highway alternatives. Mitigation measures Not applicable; no heritage resources in this category will be affected.






Risk or Likelihood

Total Score


All Alternatives Construction NA NA NA NA NA

Operation NA NA NA NA NA 9.3.8 Movable objects excluding any object made by a living person Cause and comment No records exist of records in and around Knysna for any relevant movable objects. Accordingly, it is highly unlikely that any heritage resources in this category will be affected by these routes. Mitigation measures Not applicable; no heritage resources in this category will be affected. Significance Statement



Risk or Likelihood

Total Score


All Route Alternatives- Before Mitigation Construction NA NA NA NA NA

Operation NA NA NA NA NA 9.3.9 Comparison of Alternatives The Proposed and Short Routes have the same potential moderate negative impacts on geological, archaeological and palaeontological sites and a potentially high impact on grave sites. There were no known sites that were expected to be impacted by these routes or portions of them, but various mitigation measures have been recommended in the event that such sites are encountered during the construction process. The Do Minimum option, which involves the conversion of some streets and buildings along the Waterfront area into a new one way road parallel to the current Waterfront Drive, will have potentially high negative impacts on places and buildings, sites of oral tradition and heritage, and the historical townshape but these can be mitigated to moderate levels. It will also have potentially moderate negative impacts on archaeological and palaeontological sites and graves. The Do Nothing option will have low negative impacts on places and buildings, places of oral traditions and heritage, and the historical townscape. These are all linked to the increased traffic congestion expected to characterise the CBD area. Consequently, the heritage assessment finds that there are no significantly high impacts on heritage sites and resources associated with the Knysna highway development and its alternatives that cannot be mitigated to moderate or low levels.



Table 9.2: Summary of potential heritage impacts associated with the Knysna highway development and its alternatives.

Significance Impact

Alternative Without

mitigation With mitigation

Proposed N/A N/A Short Route N/A N/A Do minimum HIGH - MODERATE -

Impact 1: Places, buildings, structures and equipment

Do Nothing LOW - N/A Proposed N/A N/A Short Route N/A N/A Do minimum HIGH - MODERATE -

Impact 2: Oral traditions/heritage places

Do Nothing LOW - MODERATE - Proposed N/A N/A Short Route N/A N/A Do minimum HIGH - MODERATE -

Impact 3: Historical settlements and townscapes

Do Nothing LOW - LOW - Proposed MODERATE - MODERATE - Short Route MODERATE - MODERATE - Do minimum N/A N/A

Impact 4: Geological sites of scientific or cultural importance Do Nothing N/A N/A

Proposed MODERATE - MODERATE - Short Route MODERATE - MODERATE - Do minimum MODERATE - MODERATE -

Impact 5: Archaeological and palaeontological sites

Do Nothing N/A N/A Proposed HIGH - HIGH - Short Route HIGH - HIGH - Do minimum MODERATE - MODERATE -

Impact 6: Graves and burial grounds

Do Nothing N/A N/A Proposed N/A N/A Short Route N/A N/A Do minimum N/A N/A

Impact 7: Sites of significance relating to the history of slavery in South Africa

Do Nothing N/A N/A Proposed N/A N/A Short Route N/A N/A Do minimum N/A N/A

Impact 8: Movable objects excluding any object made by a living person Do Nothing N/A N/A



9.4 Traffic Impacts This section assesses the potential traffic impacts associated with the Knysna Toll Highway and its alternatives. In this study, in response to concerns raised by IAPs, an additional ‘Do Minimum’ alternative has been included in this assessment. This alternative is essentially the implementation of the Knysna Municipality’s Traffic Management Plan which involves the conversion of Waterfront drive and Gordon Street into two parallel one way streets that would become the main thoroughfare through the CBD and relieve the traffic congestion along Main road. The assessment of this additional alternative was required in order to assess whether the Municipality’s Traffic Management Plan could alleviate the traffic congestion problems in Knysna and for how long. A more detailed response to these questions is provided in the Traffic Specialist Report in the specialist volume (see chapter 9, Part 2). In addition, the traffic study also assessed the potential impact that an additional interchange linked to Grey and Long/Queen streets in the CBD would have on traffic flow. The traffic specialist study identified the seven traffic impacts listed below. These are discussed in more detail in the subsections which follow.

1. Regional intercity linkages and accessibility 2. Traffic flow in Knysna streets (intra Knysna traffic) 3. Local access to Knysna 4. Access to properties around the Proposed and Short highway routes 5. Traffic safety 6. Vehicle operating costs 7. Travel time

9.4.1 Impacts of the Route Impact 1: Regional intercity linkages/accessibility Cause and Comment The regional road links to/from Knysna are currently under severe pressure during holiday times – the traffic demand exceeds the capacity of the main eastern and western links to Knysna for extended times. This results in extensive queuing during these times with the resultant traffic delays and frustration of motorists. Even during “normal” times, it takes just one incident to influence the capacity of these links and the regional accessibility is affected. This was illustrated for example in 2006 when landslides occurred after heavy rain on the section of the N2 next to the Knysna Lagoon. Even though this specific link is currently being upgraded, it remains vulnerable to incidents affecting traffic flow. The only other links from/to Knysna (excluding the N2), are the gravel roads to George and Uniondale. The capacity of these routes is severely limited, and their upgrading potential is very low, which implies, also in the absence of an operational rail link to Knysna, that the N2 links are of highest strategic importance to the successful functioning of Knysna’s economy. It is considered that these facts played an important role in the request of the Knysna Municipality to the National Roads Agency to proceed with the implementation of the Knysna Toll Highway. The proposed upgrading of the Knysna Traffic Management Plan will have almost no impact on the regional accessibility of Knysna. It limits the growth possibilities of at least some industries related to Knysna, including the tourism industry. The impact of doing nothing is similar.



Mitigation Measures In this case the only mitigation measures that are possible are the alternatives assessed in this EIA. No additional mitigation measures can be taken. The main advantage of both the Proposed and Short Options with respect to the regional linkage of Knysna is that at least two new high standard links will be created from the N2 into Knysna (the Eastwood/Salt River and Uniondale links) in addition to the existing links. This will help to separate and reduce the flow of traffic in and out of the town and result in a major improvement to the present situation and will be of high strategic value to Knysna. It will mean that business/tourist activity in Knysna can grow even further – the macro economic (multiplier effects, etc) impact will be assessed in the Economic Impact Assessment, but it should be substantial. The fact that bypass traffic, which does not have to enter Knysna, will be removed from the access routes, will also contribute to highly improved regional access to Knysna. Significance Statement



Risk or Likelihood

Total Score


PROPOSED HIGHWAY Without

Mitigation Permanent 4 Regional 3 Beneficial 4 Definite 4 15 HIGH +


SHORT HIGHWAY Without

Mitigation Permanent 4 Regional 3 Beneficial 4 Definite 4 15 HIGH +


DO MINIMUM OPTION Without

Mitigation Permanent 4 Regional 3 Severe 4 Definite 4 15 HIGH -


DO NOTHING OPTION Without

Mitigation Permanent 4 Regional 3 Severe 4 Definite 4 15 HIGH -


Impact 2: Traffic flow in Knysna streets (intra Knysna traffic) Cause and Comment The current situation where all regional (bypass) traffic has to travel through Knysna, contributes heavily to the traffic flow situation on local streets. The street system can be divided into a number of sections, but for the purposes of this investigation, three basic sections would be adequate, as shown below (Figure 9.1).



N

N2 West Knysna Central Streets N2 East

GeorgePort

Elizabeth

Figure 9.1: Schematic Illustration of the current flow of traffic through Knysna. The section referred to as N2 West is the section of the N2 west of the Main/Waterfront Street intersection and the N2 East is the section east of where Waterfront Street links with Main Road on the eastern side of Knysna CBD. The N2 West is considered the critical section of the existing route through Knysna as it is here that the demand exceeds the capacity on a regular basis and where long queuing results. The capacity of this section is not constant – it reduces in rainy weather and due to the presence of heavy vehicles. From the available recent traffic counts (CTO station 1203, excluding Brenton-on-Sea and Belvidere traffic), the highest volume recorded (two directions) is just over 1700 vehicles/hour. Note that previous information (Van Straten Associates, 2002) indicated traffic volumes of around 2000 vehicles/hour (both directions) counted just east of the White Bridge. The present capacity on this section (east of White Bridge) is accepted as 2000 vehicles/hour. A portion of this section (east of White Bridge) is presently being upgraded, which should have a positive impact on the capacity (wider lanes, wider shoulders, etc). For design purposes and in order to be conservative, a capacity of 2100 vehicles/hour (two directions) is proposed for the upgraded situation. The intersection at E (sketch above – N2/Main/Waterfront Road intersection) will however still limit this capacity to around 2000 vehicles/hour. The design demand (2008) at CTO station 1203 is 1450 vehicles/hour – to allow for the Brenton on Sea, Belvidere and Welbedacht traffic, the design demand (2008) just west of intersection E is estimated as 1700 vehicles/hour. This is expected to grow to 2000 vehicles/hour by 2013, when this section will therefore reach capacity. The Knysna Central Streets providing the east/west through function consist of Main Road and Waterfront Road. These two roads have to serve the external traffic to/from the N2 West, as well as all the local Knysna traffic. The highest volume recorded on Main Road (considered capacity) is ±1700 vehicles/hour. The capacity of Waterfront Road is estimated to be in the order of 1800 vehicles/hour. Should the Knysna Traffic Management Plan (Waterfront/Gordon Street one way system) be implemented as proposed, i.e. basically doubled to two lanes/direction, then the capacity of Waterfront/Gordon would double to 3600 vehicles/hour. The total east/west capacity for this section would then be 5300 (1700 +3600) vehicles/hour. Should the split between external



and local traffic be 50/50 (i.e. total east/west traffic in 2008 in the central section equals 2900 vehicles/hour), then this upgraded central section would reach capacity (in theory) by approximately 2025. The upgraded central section therefore would reach capacity approximately ten years later than the western section. Note that this cannot happen in practice for the “do minimum” case, as the N2 West section can not “feed” the central section with more than 2000 vehicles/hour. For the “do nothing” case, the design demand would reach capacity of the Central Streets even before 2013 and the traffic consequences will be severe. The capacity of the N2 East section varies due to the number of lanes available, but is considered not lower than 2000 vehicles/hour at present. With the design demand of 930 vehicles/hour in 2008, and the proposed traffic growth rates, this section will reach capacity by approximately 2030. Note that this assumes that the upgrading of Waterfront Road includes upgrading of Main Road up to George Rex Drive. From the analysis above it is concluded that the proposed Knysna Traffic Management Plan (Do Minimum Option) will not solve the most critical traffic capacity problem, namely the inadequate capacity of the N2 West section. By about 2013 the design demand of this section will have reached its capacity. For the Do Nothing Option the situation will be even worse. This situation is illustrated for a number of years already during holiday times, with the traffic demand exceeding the capacity on a regular basis, and the resultant long queues, high delays and severe frustration of motorists. Even during “normal” times the through traffic contributes to congestion and causes severe damage to the road pavements, which has (largely) to be maintained by the Knysna Municipality and therefore paid for by local residents. Mitigation Measures In this case the only mitigation measures that are possible are the alternatives assessed in this EIA. No additional mitigation measures can be taken. The removal of the through traffic from the Knysna streets by the Toll Highway will reduce the regional traffic volumes in Knysna by approximately 50%. This will have a high positive impact on especially the N2 West section. The impact of less traffic through Knysna Streets on business activities is expected to be low, as the bypass traffic would not have stopped in Knysna anyway. The need for the improvements which is part of the “do minimum” option could be postponed (should the toll highway be built – Proposed or Short Option). In the case of the Do Minimum option, the upgrading of Waterfront and Gordon Streets can in fact be questioned, as it will not solve the more severe problem related to the N2 West section.






Risk or Likelihood

Total Score



Mitigation Permanent 4 Study area 2 Beneficial 4 Definite 4 14 HIGH +






Mitigation Permanent 4 Study area 2 Moderate 2 Definite 4 12 HIGH -



Mitigation Permanent 4 Study area 2 Severe 4 Definite 4 14 HIGH -


Impact 3: Local Access to Knysna Cause and Comment This is the one impact where there is quite a difference between the Proposed and Short options. In the case of the Proposed option, the residents of Rheenendal, Brenton on Sea and Belvidere will experience no change to their route into Knysna – they will also not have to pay tolls. For the residents on the eastern, northern and southern sides of Knysna, there is no change to their access into Knysna – the upgraded Eastford (and other entrances) will only be beneficial to them. In the case of the Short route the Rheenendal, Brenton on Sea and Belvidere residents will have an option, either they (i) take the new longer route over the new Red Bridge and pay no tolls, or (ii) they access Knysna over the White Bridge and do pay tolls. For these residents the Short Route therefore introduces negative aspects into their journey into town. Should the toll plaza be moved to Groenvlei, then the situation is similar to the proposed option. For the Do Minimum and Do Nothing options, there is no change to the present situation. The issue of tolling (or not) is not considered a traffic matter, it is a matter of financing the N2 Toll Highway – in effect it is a matter of taxation. For some residents of the surrounding areas of Knysna (such as those in Buffels Bay, Sedgefield, etc), it introduces an unfairness, if compared to residents of (say) Brenton on Sea, as the former will be subjected to an additional tax when they travel to Knysna, while the latter group will not. It is however expected that regular travellers from say Buffels Bay and Sedgefield to Knysna will be able to apply for some form of discounted tolls. Mitigation Measures In this case the only mitigation measures that are possible are the alternatives assessed in this EIA. No additional mitigation measures can be taken. The mitigation measures for the Short Route include the construction of a new Red Bridge, which implies a longer route into town (for the western areas) as mentioned above. The option of using the White Bridge would be shorter and faster for them, but would mean paying tolls, at least in the westbound direction. The fact that



these residents will have two options of travel into Knysna, can be considered positive again. With the current proposed toll strategy, it can be expected that some residents of Brenton on Sea, Belvidere and Rheenendal could use the Short Route for their journey into town and the new Red Bridge for the journey out of town, and in this way have some benefit, but no tolls to pay, except when they travel to east of Knysna. Significance Statement



Risk or Likelihood

Total Score



Mitigation Permanent 4 Study area 2 Very Beneficial 8 Definite 4 18 VERY HIGH +






Mitigation Permanent 4 Localised 1 Slight

beneficial 1 Definite 4 10 MODERATE

+ With





Impact 4: Access to property adjacent to Proposed and Short Routes Cause and Comment The construction of the proposed and Short Routes will have an impact on access to specific properties along the routes. Retaining access to all properties is one of the design challenges that have to be solved whenever a new road is designed. This case will be no exception. The highway is to be designed as a limited access highway which will provide no direct highway access for neighbouring properties. All neighbouring properties will access the road network via existing roads and underpasses will be constructed for these roads where they cross the current road reserve. Consequently, for most existing neighbouring properties there will be no change in existing accesses. Any new developments in areas adjacent to the highway will need to develop property accesses onto the existing road network. Mitigation Measures In this case the only mitigation measures that are possible are the alternatives assessed in this EIA. No additional mitigation measures can be taken. As mentioned above feasible arrangements are included in the geometric design of the new route to allow all adjacent properties to access the road network. It is possible that these arrangements could be slightly longer than at present for specific properties, but in general the situation should be similar or better than at present.






Risk or Likelihood

Total Score



Mitigation Permanent 4 Study area 2 Slight beneficial 1 Definite 4 11 MODERATE

+ With



Mitigation Permanent 4 Study area 2 Moderately beneficial 2 Definite 4 12 HIGH+

With Mitigation Permanent 4 Study area 2 Slight

beneficial 1 Definite 4 11 MODERATE +


Mitigation Permanent 4 Localised 1 Slightly severe 1 Definite 4 10 MODERATE

- With



Mitigation Permanent 4 Localised 1 Moderately

Severe 2 Definite 4 11 MODERATE

- With


Impact 5: Traffic Safety Cause and Comment The reduction in traffic volumes through the Knysna streets will have a positive impact on road safety in Knysna itself, as conflict between vehicles and also with pedestrians will reduce substantially in the case of the highway options. In the case of the Proposed option, the long down grade on the N2, just to the west of the White Bridge, will not have to be used by the majority of vehicles and this accident black spot will therefore be avoided. The present dangerous N2/Rheenendal intersection will also be eliminated and further contribute to better traffic safety. The removal of bypass traffic from the N2 in the vicinity of the low income areas to the east of Knysna will contribute significantly to traffic safety in that area. Substantial accident reduction can therefore be associated with (especially) the Proposed option – this has been estimated in the economic analysis. As both the Proposed and Short options will be built to high geometric standards, and eliminate the intersections (and the associated conflicts) of central Knysna, their impact on traffic safety is highly positive. Adequate under and/or overpasses will be provided on the toll highway to separate pedestrians from the traffic. The ‘Do Minimum’ option will also improve traffic safety in the CBD somewhat but not to the same extent as the highway options. There would be no change in traffic safety on the N2 sections west and east of the CBD except for the deterioration in traffic safety associated with increased traffic volumes in future. The number and cost of accidents associated with this option are expected to be much higher than for the Proposed and Short options. The additional accident cost has been estimated (quantitatively) for the purposes of the micro economic analysis.



Mitigation Measures In the case of the “Do Minimum” option, special measures will be required to mitigate vehicle conflict as well as vehicle/pedestrian conflict in the streets of Knysna as much higher traffic volumes (than presently) through Knysna will have to be handled in the future. These measures could include special signalised pedestrian crossings, as well as adequate allowance at other signalised (and non-signalised) intersections for pedestrians and cyclists. Over and/or underpasses will be required in the vicinity of the low income residential areas to the east of Knysna. Traffic calming (such as speed bumps and raised intersections), should not be implemented, as the Waterfront/Gordon Street one way pair should have a mobility function. Significance Statement



Risk or Likelihood

Total Score



Mitigation Permanent 4 Study area 2 Beneficial 4 Definite 4 14 HIGH+



Mitigation Permanent 4 Study area 2 Moderate beneficial 2 Definite 4 12 HIGH+





- With

Mitigation Permanent 4 Localised 1 Slightly Severe 1 Definite 4 10 MODERATE

- DO NOTHING OPTION

Without Mitigation

Permanent 4 Localised 1 Severe 4 Definite 4 13 HIGH-

With Mitigation

N/A 4 N/A 1 N/A 4 N/A 4 N/A

Impact 6: Vehicle Operating Cost Cause and Comment The impact of constructing the toll highway on vehicle operating costs will be highly positive, both for bypassing traffic and traffic destined for Knysna. With further traffic growth, congestion through Knysna will occur over longer and longer periods (than presently), more queuing will be evident, the wastage of fuel will increase and general wear and tear will also increase. This is especially true for heavy vehicles. The toll highway will cause substantial operational cost savings for longer distance (bypass) traffic, even should the toll fees be taken into account. The saving in vehicle operating cost has been estimated in the micro economic analysis and the extent can be seen in Chapter 9.3 of the Specialist Volume.



Mitigation Measures In this case the only mitigation measures that are possible are the alternatives assessed in this EIA. No additional mitigation measures can be taken. In the case of the Do Minimum option, some improvement should occur due to the proposed Traffic Management Plan, but this improvement has limitations to the extent of its impact. The real solution from a traffic viewpoint (for Do Minimum option) is the further widening of the section of the existing N2 between the White Bridge and the Main/Waterfront intersection to two lanes per direction. This is so environmentally sensitive, that the chances for implementation are considered highly unlikely. The Do Minimum will therefore remain with a serious flaw, namely the lack of adequate capacity over this specific section. Significance Statement



Risk or Likelihood

Total Score



Mitigation Permanent 4 Study area 2 Beneficial 4 Definite 4 14 HIGH+



Mitigation Permanent 4 Study area 2 Moderately beneficial 2 Definite 4 12 HIGH+





- With





Impact 7: Travel Time Cause and Comment The impact of not constructing the toll highway on travel time will be similar to that of vehicle operating cost described above. Currently the journey through Knysna is already time consuming and frustrating to road users, especially during holiday times. This situation will only deteriorate over time. The additional capacity of the toll highway and the removal of through traffic from Knysna’s streets will contribute to a highly improved situation. This has been estimated and included in the economic analysis . Mitigation Measures In this case the only mitigation measures that are possible are the alternatives assessed in this EIA. No additional mitigation measures can be taken. As for the situation with the vehicle operating cost, the improvements to travel time possible with the Traffic Management Plan, are very limited. The capacity increase is limited and numerous intersections with conflicting traffic and pedestrians will remain.





Impact

Risk or Likelihood

Total Score






Mitigation Permanent 4 Study area 2 Moderate beneficial 2 Definite 4 12 HIGH +





- With





9.4.2 Impacts of the Alternative Interchanges and link roads The appropriateness and impacts of the three alternative main interchanges and link roads into the CBD are considered in this section. These three interchanges are the Eastford, Salt River and the Grey/Long street interchanges. While the Salt River link is considered an alternative to the Eastford link, as indicated in section 9.4.1 of the Specialist Volume and section 4.4.4 of the EIR, the Grey Street link is not considered appropriate as an alternative to the Eastford or Salt River interchanges, but could be considered as an additional interchange and link road. The relative impacts of these interchanges on traffic flow, safety and travel costs and times are evaluated below. Impact on traffic flow From a traffic flow viewpoint the difference between the Eastford and Salt River interchanges/link roads is negligible as they will both serve the same function and will not result in any significant differences in traffic flow in the CBD. The Grey/Long Street interchange will have some advantage if it were to serve as an additional access to Knysna and thereby distribute Knysna bound traffic more. However, it is not required from a capacity viewpoint and it links with Main Road in the centre of town where the additional traffic can not easily be accommodated, i.e. at an undesirable location.





Impact

Risk or Likelihood

Total Score


EASTFORD INTERCHANGE Without

Mitigation Permanent Regional Very beneficial Definite k19 VERY HIGH +


SALT RIVER INTERCHANGE Without

Mitigation Permanent Regional Very beneficial Definite 19 VERY HIGH +


GREY/LONG STREET INTERCHANGE Without

Mitigation Permanent Regional Severe Definite 15 HIGH -

With Mitigation

N/A N/A N/A N/A N/A N/A

Impact on traffic safety The construction of the Proposed or the Short Highway will improve traffic safety in the Knysna CBD. However, this does not mean that there will be no traffic safety hazards with these options. From a traffic safety viewpoint there would be a small difference between the Eastford and Salt River interchanges/link roads as the latter involves a slightly longer distance of travel on a high standard toll highway. This does not take into account any traffic safety issues associated with steep slopes on these interchanges and link roads. The Grey/Long Street link road will have steep downgrades which introduces safety hazards. It also brings traffic to the activity portion of Central Knysna which is negative from a pedestrian safety viewpoint.



Risk or Likelihood

Total Score



Mitigation Permanent Regional Beneficial Definite 15 HIGH +






Mitigation Permanent Regional Severe Definite 15 HIGH -

With Mitigation


Impact on travel time and costs From a travel time viewpoint, the Salt River link could be slightly advantageous (if compared with Eastford) as it involves a longer distance of travel on the high standard toll highway and a shorter link road.



The Grey Street Link will provide time savings from longer travel on toll highway, but these savings would be offset by the expected congestion of Main Road in Central Knysna.



Risk or Likelihood

Total Score










With Mitigation


9.4.3 Conclusions to Traffic Impact Assessment The traffic impacts of the Proposed and the Short highway options are largely (but not totally) similar, but they differ substantially from the “Do Minimum” and “Do-Nothing” options (see Table 9.3 for a summary). In view of the traffic flow problems presently experienced in Knysna, the impacts of any improvements to these problems are considered positive. Consequently, the three options that will result in some traffic flow improvements, are considered positive/beneficial. The traffic consequences of doing nothing are highly negative. More specifically the two highway options will have highly positive impacts on regional intercity linkages, traffic flow in Knysna town, access to properties adjacent to the highway, traffic safety, vehicle operating costs, and travel time. The only difference between the two highway options is that of access to Knysna for local residents. Residents on the west bank of the Knysna river will be affected by toll fees on their way home from the CBD in the case of the Short Route with the Eastford toll plaza site, unless they can take an alternative route. The proposed non-toll alterative is to upgrade the Red Bridge for one way traffic and the access roads along the banks of the river. This would provide them with a scenic but much longer and slower route home. Their access routes out of town will therefore not be as beneficial as that of the Proposed Route, if the westbound toll plaza for the Short Route is located at Eastford. The analysis of the traffic data concluded that the proposed Knysna Traffic Management Plan (Do Minimum Option) will not solve the most critical traffic capacity problem, namely the inadequate capacity of the N2 West section. By about 2013 the design demand of this section will have reached its capacity. Consequently, although the Do Minimum will moderately improve access locally, it will have highly negative impacts on regional linkages, Knysna traffic flow, and access to properties along the road reserve, and moderately negative impacts on traffic safety, vehicle operating costs and travel time. In the case of the Do Nothing Option the situation will be even worse with no benefits and all traffic impacts being highly negative.



Table 9.3: Summary of potential Traffic Impacts for the Knysna Toll Highway and its alternatives Impacts Alternatives Without With mitigation

Proposed Highway HIGH + N/A Short highway HIGH + N/A Do minimum option HIGH - N/A

Impact 1: Regional intercity linkages/accessibility

Do nothing option HIGH - N/A Proposed Highway HIGH + N/A Short highway HIGH + N/A Do minimum option HIGH - N/A

Impact 2: Traffic flow in Knysna streets (intra Knysna traffic)

Do nothing option HIGH - N/A Proposed Highway VERY HIGH + N/A Short highway HIGH + N/A Do minimum option MODERATE + N/A

Impact 3: Local access to Knysna

Do nothing option HIGH - N/A Proposed Highway HIGH + N/A Short highway HIGH + MODERATE + Do minimum option MODERATE - N/A

Impact 4: Access to property around proposed and Short Routes

Do nothing option MODERATE - N/A Proposed Highway HIGH + N/A Short highway HIGH + N/A Do minimum option MODERATE - MODERATE -

Impact 5: Traffic safety

Do nothing option HIGH - N/A Proposed Highway HIGH + N/A Short highway HIGH + N/A Do minimum option MODERATE - N/A

Impact 6: Vehicle operating costs

Do nothing option HIGH - N/A Proposed Highway HIGH + N/A Short highway HIGH + N/A Do minimum option MODERATE - N/A

Impact 7: Travel time

Do nothing option HIGH - N/A For most of the traffic impacts, the alternatives are the only possible mitigation measure, so no other mitigation measures are suggested. Based on the micro economic and life cycle cost analysis, the following is the order of ranking of the alternatives, from the best to the worst Life Cycle cost: Ranking Route Present Worth of Cost

1 Proposed Route Alternative R 23 124 765 000 2 Short Route Alternative R 26 137 344 000 3 “Do Minimum” Alternative R 54 431 511 000 4 “Do Nothing Alternative R 74 887 329 000

These cost estimates take into consideration the vehicle operating costs, travel time costs and accident costs. The present worth of the total cost saving (benefits) of the Toll Highway alternatives over the 25 year analysis period, of approximately R30 billion and R50 billion, indicates very high benefit cost ratios and clearly proves the economic feasibility of the Toll Highway project. This analysis indicates that from a micro economic viewpoint, the implementation of both the Proposed Route Alternative and the Short Route Alternative is clearly justified. With respect to the possible linking of Grey/Long Streets to the Toll Highway (via an interchange), the traffic assessment concluded that the linking of Grey/Long Streets with the proposed Knysna Toll Highway was undesirable from a traffic viewpoint and should not be pursued.



9.5 Landscape and Visual Impacts This chapter focuses on the landscape and visual impacts during the construction and operation phase for the routes, bridges, interchanges, underpasses and toll plazas. The activities that are expected to cause landscape and visual impacts in the construction phase are listed below. These activities will create surface disturbances, which will result in the removal of vegetation, the exposure of the underlying soils and changes to the landform. More specifically these include:

• Clearing of vegetation for roadway, road reserve, construction camps and stock piling; • Cut and fill activities; • Rock blasting and crushing (earthworks); • Grading and levelling; • Finishing and grading; • Road surfacing; • Dust from construction activities; and • Destruction and damage to sensitive coastal vegetation and estuary.

Construction activity will fluctuate in intensity along the length of the alignment during the construction phase. Parcels of exposed soil will be a typical characteristic of the construction phase. Construction sites will appear disorganised and dispersed with construction equipment, material stockpiles and supporting facilities. Large construction equipment will be used for the construction of bridges, cut and fill and for road surfacing. Dust clouds may be generated by these activities. Operational phase: After the construction phase, the completed toll highway will introduce new elements that will alter the existing land cover and sometimes alter the character of the study area. The hard-scape and associated structures will replace natural vegetation. The completed toll highway will be an improvement from the construction phase and can include rehabilitation and landscaping activities. Surface disturbances created during construction may remain for an extended period during the operational phase. These are considered as residual effects carried forward from the construction phase and can be completely or substantially mitigated if treated appropriately during the construction phase. Some are new activities and components arising from the completion of the project. These arise from a change in the existing land uses with the proposed project components. The following are possible impacts, or sources of risk that can be anticipated:

• Possible change in the overall natural or rural character (ambience) of the area; • Possible visual intrusion on sensitive receptors along the proposed alternatives; • Possible increase of lighting from the development at night, particularly in relation to the

vehicle lights, toll plaza lights and street lighting at various intersections; • Possible increase in visual intrusions (visual 'disorder') resulting from signage and other

infrastructure being introduced to the area; • The night-time light impacts to the surrounding environment in particular the toll plaza

signal lights, traffic and flood lights; • Decrease or appreciation in property values adjacent the proposed development; • Possible change in character could have negative implications for the visual quality and

ambience of the area especially to residential areas in close proximity to where the highway will traverse;

• Possible immediate and long-term degradation of sensitive habitats for coastal and marine environments due to a change in ecological processes;



• An increase in the number of bridge structures over the Knysna River can be to the detriment of the visual quality and scenic views of many residential and tourist accommodation properties in study area; and

• The upgrading of the infrastructure could have a beneficial visual impact in some cases, for instance the ease in traffic congestion and reduction in accidents.

9.5.1 Landscape Impacts: Method of Assessment During the construction and operational phases, the project components are expected to impact on the landscape character types they traverse. The magnitude or severity of these impacts is measured against the scale of the project, the permanence of the intrusion and the loss in visual quality, value, and/or Visual Absorbtion Capacity (VAC). The severity of landscape impacts during the construction phase is anticipated to be high but short-lived. The construction activities will have a negative impact on the visual quality of the landscape due to the presence of construction camps, road signage, and a loss of vegetation cover. With the recommended mitigation measures in place, the impacts can be reduced significantly in most cases. Due to the high sensitivity of the Cape Estuarine and Lagoon landscapes, the impact on these landscapes is considered high but short-lived in the construction phase, and moderate but sustained in the operational phase. The Landscape Character Sensitivity analysis was used to assess the landscape impacts of the proposed. This analysis differs for natural and built environments. The factors incorporated into this analysis for these two types of environments are described below before moving on to discuss the significance of the landscape impacts for the Knysna Toll Highway project. Natural environment The sensitivity of the landscape character is an indication of “…the degree to which a particular landscape can accommodate change from a particular development, without detrimental effects on its character” (GLVIA, 2002). A landscape with a high sensitivity would be one that is greatly valued for its aesthetic attractiveness and/or have ecological, cultural, or social importance through which it contributes to the inherent character of the visual resource. The assessment of the sensitivity of the different landscape character types is substantiated through an informed judgement based on the landscape character assessment in Table 9.4 and 9.5 below. Table 9.4: Categorisation of approaches used for visual assessment (DEA & DP

TYPE OF ISSUE

APPROACH Little or no visual impact

expected

Minimal visual impact expected

Moderate visual impact expected

High visual impact expected

Very high visual impact expected

LEVEL OF VISUAL INPUT

RECOMMENDED

Level 1 visual input

Level 2 visual input

Level 3 visual assessment Level 4 visual assessment

A landscape sensitivity rating was adapted from GOSW (2006) and applied in the classification of the study area into different sensitivity zones.



Table 9.5: Landscape character sensitivity rating (Adapted from GOSW, 2006) SENSITIVITY DESCRIPTION

Low

These landscapes are likely to: • Have distinct and well-defined landforms; • Have a strong sense of enclosure; • Provide a high degree of screening; • Have been affected by extensive development or man-made features; • Have reduced tranquillity; • Are likely to have little inter-visibility with adjacent landscapes; and • Exhibit no or a low density of sensitive landscape features that bare visual value.

Moderate

These landscapes are likely to: • Have a moderately elevated topography with reasonably distinct landforms that provides

some sense of enclosure; • Have been affected by several man-made features; • Have limited inter-visibility with adjacent landscapes; and • Exhibit a moderate density of sensitive landscape features that bare visual value.

High

These landscapes are likely to: • Consist mainly of undulating plains and less distinctly defined landforms; • Be open or exposed with a remote character and an absence of man-made features; • Are often highly visible from adjacent landscapes; and • Exhibit a high density of sensitive landscape features that bare visual value.

Built Environment A different approach is required for assessing potential impacts on an existing urban framework. Urban settings are usually considered less sensitive to additional development because they are already disturbed and not in their natural state. However, Knysna central business district’s character is composed of contemporary, heritage buildings and waterfront spaces that have gained local significance. It is important to assess the sensitivity of the townscape and landscape to safeguard such areas from disturbance. Refer to Table 9.6 and 9.7 respectively. Table 9.6: Townscape Character Sensitivity Rating (Adapted from ‘The Environmental Dimension LLP, 2007’)

SENSITIVITY DESCRIPTION

Low

These townscapes are likely to: • Townscape area or setting of feature where the general mixture of elements result in an

indistinct and ambiguous character; • Where the man-made, historic and natural elements are evidently discordant and in a

degraded condition; and • Where there are several detractors and poor scenic quality.

Moderate

These landscapes are likely to: • Townscape area or setting of feature with a diversity of elements which combine to

produce a recognisable but inconsistent character, • Where the man-made, historic and natural elements are generally balanced and in fair

condition; and • Where there are some detractors but overall, a pleasant scenic quality.

High

These landscapes are likely to: • Townscape area or setting of feature with some diversity but where elements combine

well to produce a clear, distinct and integrated character over most areas; • Where the man-made, historic and natural elements are harmonious and in good

condition; and • Where there are few detractors and high scenic quality.



Table 9.7: Landscape Character Sensitivity

LANDSCAPE CHARACTER TYPE

PREVAILING TOWNSCAPE

AREA OF DISTURBANCE IN LANDSCAPE TYPE

Knysna Built Environment Moderate

• Waterfront Drive; • Gordon Street; • Trotter Street; • The Royal Herberg – N2; • Knysna Spar Area – N2; • Wayside Inn - N2; and • Church Square – N2

PREVAILING LANDSCAPE CHARACTER SENSITIVITY

Cape Estuarine & Lagoon High • White Bridge crossing; and

• New crossing next to the Red Bridge

Garden Route Shale Fynbos Low

• Residential areas (Eastford, West Hill & Khayalethu);

• Commercial forestry areas north of Knysna CBD; and

• Commercial & industry areas near the CBD.

Knysna Sand Fynbos Moderate • Residential housing; • Informal housing; and • Forestry.

Southern Afrotemperate Forest Low

• Residential and farm houses west of the proposed Buffelsvermark toll plaza; and

• Informal housing north of Knysna CBD 9.5.2 Landscape Impacts for the Routes, Intersections, Bridges, Underpasses & Toll

Plazas 9.5.2.1 Routes Proposed Route: Approximately 73% of this alignment will be made up a new road. Large portions of undisturbed or undeveloped landscape along the alignment will be cleared to accommodate the highway and its components. The project components will alter the existing vegetation fabric along and adjacent the alignment, this will result in exposure of underlying soils and alteration to the existing character of the landscape. The size and location of the construction camps will play an additional role in increasing the severity of the landscape impact. Short Route: Approximately 55% of this alignment will be made up a new road. Areas of undisturbed or undeveloped land along the alignment will be cleared to accommodate the highway and its components. The construction of new sections of the highway will result in massive earthworks, clearing of sensitive indigenous vegetation and disturbance to adjacent properties. The project components will alter the existing fabric along and adjacent to its alignment, expose the underlying soils and modify the character of the landscape. During the operational phase, the roadway and other elements will replace vegetation cleared for the construction of the toll highway along the route. Disturbed vegetation in the road reserve can take time to recover from the damage inflicted during the construction phase. Cut landscape and rock faces will be left scarred if not rehabilitated, leading to soil erosion or collapse



Significance statement for the Landscape impacts of the Routes (Construction) Effect

Impact Temporal

Scale Spatial Scale Severity of

Impact Risk or

Likelihood Total Score


Proposed Route

Without Mitigation

Short term 1

Study area 2

Very severe 8 Definite 4 15 HIGH -

With Mitigation

Short term 1

Study area 2 Severe 4 Definite 4 11

MODERATE -

Short Route

Without Mitigation

Short term 1

Study area 2


With Mitigation

Short term 1 Localised 1


Significance statement for the Landscape Impacts of the Routes (Operational)

Effect


Impact Risk or



Proposed Route

Without Mitigation Permanent 4

Study area 2 Moderate 2

May occur 2 10

MODERATE -

With Mitigation Permanent 4 Localised 1 Slight 1

May occur 2 8

MODERATE -

Short Route



May occur 2 10

MODERATE -

With Mitigation Permanent 4 Localised 1 Slight 1

May occur 2 8

MODERATE -

9.5.2.2 Road Bridges/Intersections The proposed road bridges and interchanges will entail the construction of large structures necessary to raise the toll highway road over other smaller roads that it may intersect. A significant footprint will be cleared for construction purposes to accommodate the proposed interchanges. Eastford Interchange: This intersection is located in an indigenous forest environment, clearing will be necessary to construct the interchange. The character of the landscape in this area will likely be transformed by the introduction of the proposed interchange. The residential properties within the vicinity can be affected negatively due to the altering of the character in this area. A significant footprint will be cleared for construction purposes around the area to accommodate the highway and the interchange.

Salt River Interchange: This is a partial interchange; it will be located in the heart of Salt River Valley. The most significant landscape impacts will be the disturbance of the Salt River flood plains and its banks. The residential properties within the vicinity can be affected negatively due to the altering of the character in this area. A significant footprint will be cleared for construction purposes around the area to accommodate the highway and the interchange. Cleared vegetation will take time to establish. Uniondale/ R339 Road Bridge: This location does not require much clearing but extensive earthworks will be necessary to raise the toll highway over the R339. The interchange and road bridge will have a significant landscape impacts in the operational phase. The character of this undeveloped rural environment will be transformed to an urban character



Rheenendal, Springfield and Brackenhill Interchanges: The interchange is located in a commercial forest environment; the landscape impact will be high due to the high vegetation cover that will be removed to accommodate the interchange. The interchange and road bridge will have a significant landscape impacts in the operational phase. The character of this undeveloped rural environment will be transformed to an urban character. Significance statement for the Landscape Impacts of the Road Bridges/Interchange (Construction)

Effect

Impact Temporal


Impact Risk or



Eastford Interchange Without

Mitigation Short term 1 Localised 1 Severe 4 Definite 4 10 MODERATE

_ With

Mitigation Short term 1 Localised 1 Moderate 2 Definite 4 8 MODERATE

_

Salt River Interchange Without

Mitigation Short term 1 Localised 1 Severe 4 Definite 4 10

MODERATE _

With Mitigation

Short term 1 Localised 1 Moderate 2 Definite 4 8

MODERATE _

Uniondale/R339 Road Bridge

Without Mitigation

Short term 1


MODERATE _

With Mitigation

Short term 1

Study area 2 Moderate 2 Definite 4 9

MODERATE _

Rheenendal Interchange (PR)

Without Mitigation

Short term 1 Study

area 2 Very severe 8 Definite 4 15 HIGH -

With Mitigation

Short term 1 Study

area 2 Severe 4 Definite 4 11 MODERATE _


Mitigation Short term 1 Study


With Mitigation

Short term 1 Study


Brackenhill Interchange Without



With Mitigation

Short term 1 Study


Significance statement for the Landscape Impacts of the Road Bridges/Interchange (Operation)

Effect


Impact Risk or



Eastford Interchange

Without Mitigation Permanent 4 Localised 1 Severe 4 Probable 3 12 HIGH -



Effect


Impact Risk or



With Mitigation Permanent 4 Localised 1 Moderate 2 Probable 3 10 MODERATE

-

Salt River Interchange Without

Mitigation Permanent 4 Localised 1 Severe 4 Probable 3 12 MODERATE -


-

Uniondale/R339 Road Bridge Without

Mitigation Short term 1 Study area 2

Very severe 8

May occur 2 13 HIGH -

With Mitigation Short term 1

Study area 2 Severe 4

May occur 2 9

MODERATE -

Rheenendal Interchange (PR)

Without Mitigation Permanent 4 Study

area 2 Very severe 8 Probable 3 17 VERY HIGH

- With

Mitigation Permanent 4 Study area 2 Severe 4 Probable 3 13 HIGH -


Mitigation Permanent 4 Study area 2 Very

severe 8 Probable 3 17 VERY HIGH -

With Mitigation Permanent 4 Study

area 2 Severe 4 Probable 3 13 HIGH -

Brackenhill Interchange Without

Mitigation Permanent 4 Study area 2 Very

severe 8 Probable 3 17 VERY HIGH -


area 2 Severe 4 Probable 3 13 HIGH -

9.5.2.3 River Bridges and Viaduct This section refers to the Salt River crossing which is common to both the proposed and Short Route, the Knysna River Bridge which is specific to the Proposed Route and the White Bridge Viaduct which is specific to the Short Route. Four types of bridge crossings are being considered for the Salt River (Central) crossing.

Bridge Type A : Bridges type A will have the greatest landscape footprint due to the high number of piers used to cross the Salt River. This bridge type A make use of 5 piers per carriageway, making 10 piers for the entire bridge. Large amounts of earth will be required to construct the embankment structure on both ends of the bridge. On bridge type A there is an additional ramp D to join the underpass from the proposed highway, this increases the footprint disturbance of the bridge design as whole. Bridge Type B: This Bridge type will have a reduced landscape footprint compared to bridge type A and D. The bridge will span the Salt River flood plains on an A-frame tower. This bridge type will cause landscape impacts, which are limited to the tower footprint and embankment structures at both ends of the riverbank. Bridge Type C: This Bridge will have a reduced landscape footprint with 8 piers compared to bridge type A and D with 10 piers. Landscape impacts are limited to only the 8 pier structures, which include the central Arch, and abutment structures at both ends.



Three types of bridge crossings are being considered for the Knysna River / Lagoon crossing (Proposed only). All three will have varying landscape impacts.

Bridge Type A: This Bridge type has the greatest landscape footprint hence the greatest landscape impacts compared to the other two bridge type B and C. Large amounts of earth will be required to construct the embankment structure of bridge type A. The embankment structure will disturb the tidal flow of the river and encroach on the flood plains. Bridge Type B: This Bridge type will have a reduced landscape footprint compared to bridge type A. The bridge will span the flood plains and river on piers. This bridge type will cause landscape impacts, which are limited to the piers and the short abutment structure over the flood plains. The embankment structure will disturb the tidal flow of the river and encroach on the flood plains. Bridge Type C: This Bridge will have the least landscape impacts compared to the proposed bridge designs A and B. Landscape impacts are limited to only the caisson/ pier structures and the anchorage points of the bridge.

White Bridge Viaduct (Short Route only) Widening of the fill section over the mud flats of the Knysna River will be required to construct the viaduct which will raise this road section above and over the lagoon road and up the ravine towards the Eastford interchange. The ravine has portions of sensitive red data species that will be impacted by the construction activities of the viaduct. There will be the temporary construction of a traffic accommodation road over the mud flats during the construction period, this temporary structure may interfere with the tidal flow of the river and cause possible long-term disturbance of coastal environment. As the viaduct will rise for most of its length on piers, this will limit the landscape impacts to pier footprints only for this section. The widened White bridge will lead to additional support structures including embankment structures over the mud flats of the Knysna River. Significance statement for the Landscape Impacts of the River Bridges (Construction)

Effect

Impact Temporal


Impact Risk or



Salt River Bridge Type A

Without Mitigation


Very Severe 8 Definite 4 14 HIGH -

With Mitigation

Short term 1 Localised 1 Moderate 2 Definite 4 8 MODERATE-

Salt River Bridge Type B

Without Mitigation


With Mitigation


Salt River Bridge Type C

Without Mitigation

Short term 1 Localised 1 Severe 4 Probable 4 10 MODERATE-

With Mitigation

Short term 1 Localised 1 Moderate 2 Probable 4 8 MODERATE-

Salt River Bridge Type D Without

Mitigation Short term 1

Study area 1




Effect

Impact Temporal


Impact Risk or



With Mitigation

Short term 1

Study area 1 Moderate 2 Definite 4 9 MODERATE-

Knysna River Bridge Type A

Without Mitigation



With Mitigation

Short term 1 Localised 1 Severe 4 Definite 4 10 MODERATE-

Knysna River Bridge Type B

Without Mitigation


With Mitigation


Knysna River Bridge Type C

Without Mitigation

Short term 1 Localised 1 Severe 4 Probable 3 9 MODERATE-

With Mitigation

Short term 1 Localised 1 Moderate 2 Probable 3 7 LOW -

Whitebridge Viaduct (SR)

Without Mitigation



With Mitigation


Significance statement for the Landscape Impacts of the River Bridges/Viaduct (Operational)

Effect

Impact Temporal


Impact Risk or




Without Mitigation

Long term 3 Localised 1 Moderate 2 Probable 3 9

MODERATE -

With Mitigation

Long term 3 Localised 1 Slight 1 Probable 3 8

MODERATE -


Without Mitigation


MODERATE -

With Mitigation


MODERATE -


Without Mitigation


MODERATE -

With Mitigation


MODERATE -


Mitigation Long term 3 Localised 1 Moderate 2 Probable 3 9

MODERATE -

With Mitigation


MODERATE -



Effect

Impact Temporal


Impact Risk or




Without Mitigation

Long term 3 Localised 1 Severe 4 Probable 3 11

MODERATE -

With Mitigation


MODERATE -


Without Mitigation


MODERATE -

With Mitigation


MODERATE -


Without Mitigation


MODERATE -

With Mitigation

Long term 3 Localised 1 Slight 1 Probable 3 8 LOW -


Without Mitigation


VERY HIGH -

With Mitigation

Long term 3 Localised 1 Severe 8

May occur 2 14 HIGH -

9.5.2.4 Underpasses Lagoon and Concordia Underpass: The underpasses will be constructed over gravel roads and portions around the underpass may be upgraded to a tar surface as part of the underpass construction. Uniondale Underpass: To construct the underpass entails extensive earthworks in the case an embankment structure is chosen to elevate the highway from existing Uniondale road. Alternatively, if a structure is utilised the earthworks will be limited to the foundation footings. The upgrading of portions of the roads that intersect with the highway underpass will alter the character of the local area through the introduction of hard paving surfaces and landscaping in these areas. Significance statement for the Landscape Impacts of the Underpasses (Construction)

Effect

Impact Temporal


Impact Risk or



Lagoon Underpass

Without Mitigation

Short term 1 Localised 1 Severe 4

May occur 2 8

MODERATE -

With Mitigation

Short term 1 Localised 1 Moderate 2

May occur 2 6 LOW -

Concordia Underpass Without

Mitigation Short term 1 Localised 1 Severe 4

May occur 2 8

MODERATE -

With Mitigation


May occur 2 6 LOW -



Significance statement for the Landscape Impacts of the Underpasses (Operational)

Effect

Impact Temporal


Impact Risk or



Lagoon Underpass

Without Mitigation

Short term 1 Localised 1 Moderate 2 Unlikely 1 5 LOW -

With Mitigation

Short term 1 Localised 1 Slight 1 Unlikely 1 4 LOW -

Concordia Underpass Without

Mitigation Short term 1 Localised 1 Moderate 2 Unlikely 1 5 LOW -

With Mitigation


9.5.2.5 Toll Plazas Groenvlei Toll Plaza: The construction of the toll plaza in this location will not affect any sensitive receptors including recreational user of Groenvlei Lake and Goukamma Nature Reserve, only motorist driving along the N2 will be exposed to the construction activities of the toll plaza in this location. Portions of the commercial forest areas may be removed to provide adequate approach and road reserve for the highway. Buffelsvermark Toll Plaza (Proposed only): Vegetation type affected is the Knysna Sand Fynbos, which is highly sensitivity due to its high plant diversity and ecological value will be lost to site clearing activities The Eastford toll plaza (Short only) is located within a residential area; the toll plaza will alter portions of the landscape thereby altering the residential fabric and character of this locality. Springfield and Brackenhill Toll Plazas The toll plaza is located within commercial forest areas. Portions of the commercial forest areas may be removed to provide adequate road width approach for the toll plaza. Significance statement for the Landscape Impacts of the Toll Plazas (Construction)

Effect

Impact Temporal


Impact Risk or



Groenvlei Toll Plaza

Without Mitigation

Short term 1 Localised 1 Severe 4 Definite 4 10

MODERATE -

With Mitigation


MODERATE -

Eastford Toll Plaza

Without Mitigation



With Mitigation


MODERATE -

Buffelsvermaak Toll Plaza

Without Mitigation



With Mitigation


MODERATE -



Effect

Impact Temporal


Impact Risk or



Springfield Toll Plaza Without

Mitigation Short term 1 Localised 1


With Mitigation


MODERATE -

Brackenhill Toll Plaza Without

Mitigation Short term 1 Localised 1 Very

severe 8 Definite 4 14 HIGH - With

Mitigation Short term 1 Localised 1 Severe 4 Definite 4 10 MODERATE

- Significance statement for the Landscape Impacts of the Toll Plazas (Operational)

Effect


Impact Risk or






-

Eastford Toll Plaza Without

Mitigation Permanent 4 Study area 2 Severe 4 Probable 3 13 HIGH -


area 2 Moderate 2 Probable 3 11 MODERATE -




- Springfield Toll Plaza



- Brackenhill Toll Plaza



- 9.5.3 Visual Impacts: Method of Assessment Severity of visual impact refers to the magnitude of change to specific visual receptor’s views and/or experience of the landscape. Severities of visual impacts are influenced by the following factors:

• The viewer’s exposure to the project: o Distance of observers from the proposed project; o The visibility of the proposed project (Zone of Visual Impact - ZVI); o Number of affected viewers; and



o Duration of views to development experienced by affected viewers. • Degree of visual intrusion created by the project.

The visual impacts on the residents and tourists are assessed in terms of occurrence and severity, which are further divided into probability and duration, as well as magnitude and scale respectively. It is anticipated that the visual impact on residents and tourists will vary depending on their location in relation to the toll highway. Specific areas are exposed to prolonged views of the toll highway and its associated structures in the construction and operational phases, especially those adjacent to the proposed project. 9.5.3.1 Viewer Sensitivity Within the receiving environment, specific viewers (visual receptors) experience different views of the visual resource and value it differently. They will be affected because of alterations to their views due to the proposed project that can obstruct or introduce new elements. Visual receptors are grouped according to their similarities in sensitivity. A viewer group is a collection of viewers that are involved with similar activities and experience similar views of the proposed development. Within the receiving environment, specific visual receptors experience unique views of the proposed development. They will be affected due to the alteration of their views and are therefore identified as part of the receiving and affected environment. The visual receptors included in this study are:

• Residents; and • Tourists;

Due to the similarity of the expectations, sensitivity and, at times, location these two groups residents and tourists, will be assessed as one group and will be referred to as Sensitive Viewers (Visual Receptors). 9.5.3.2 Land-use and Viewer Sensitivity Classification Land uses have been classified into areas of low, moderate and high visual sensitivity (see Table 9.8). Table 9.8 Land use and visual receptor sensitivity

9.5.3.3 Visual Quality Visual quality is a qualitative evaluation of the composition of landscape features and their scenic attractiveness. Factors contributing to the visual quality of the landscape and are grouped under the following main categories (Table 9.9) that are internationally accepted indicators of visual quality (FHWA, 1981):

LAND USE VISUAL RECEPTOR (VIEWER) SENSITIVITY CLASS

Commercial / Industrial; Commercial Forestry; and Mining Low

Cultivated Land, Subsistence Farming and Vacant / Unspecified Land Moderate

Conservation; Residential; and Tourism High



Table 9.9: Criteria of Visual Quality (FHWA, 1981) INDICATOR CRITERIA

Vividness The memorability of the visual impression received from contrasting landscape elements as they combine to form a striking and distinctive visual pattern.

Intactness The integrity of visual order in the natural and man-built landscape, and the extent to which the landscape is free from visual encroachment.

Unity The degree to which the visual resources of the landscape join to form a coherent, harmonious

visual pattern. Unity refers to the compositional harmony of inter-compatibility between landscape elements.

To calculate the visual quality the landscape is allocated a rating from an evaluation scale of 1 to 7 and divided by 3 to get an average. The evaluation scale is as follows: Very Low =1; Low =2; Moderately-Low =3; Moderate =4; Moderately-High =5; High =6; and Very High =7. The landscape character types are assessed against each indicator separately. All three indicators should be high to obtain a high visual quality. The visual quality is assessed on a regional scale and therefore expresses the predominant visual quality of each landscape character type. Refer to Table 9.10 Table 9.10: Visual Quality of Landscape character types

LANDSCAPE CHARACTER TYP VIVIDNESS INTACTNESS UNITY VISUAL QUALITY

Knysna Built Environment 4 3 2 Moderately-low

Cape Estuarine & Lagoon 3 5 5 Moderate

Garden Route Shale Fynbos 6 4 4 Moderately High

Knysna Sand Fynbos 6 4 4 Moderately High

Southern Afrotemperate Forest 3 4 4 Moderate 9.5.3.4 Visual Absorption Capacity (VAC) Visual Absorption Capacity (VAC) signifies the ability of the landscape to accept additional human intervention without serious loss of character and visual quality or value. VAC is founded on the characteristics of the physical environment such as:

• Degree of visual screening • Terrain variability • Land cover

A rating system is used to evaluate each landscape character type against the three VAC parameters. The values are relative and relate to the type of project that is proposed and how it may be absorbed in the landscape. A three-value range is used, three (3) being the highest potential to absorb an element in the landscape and one (1) being the lowest potential. The values are summed and categorised in a high, moderate or low VAC rating. Table 9.11: Visual Absorption Capacity evaluation LANDSCAPE CHARACTER TYPE

VISUAL SCREENING

TERRAIN VARIABILITY LAND COVER VAC

Knysna Built Environment 3 0 3 Moderate Cape Estuarine & Lagoon 1 1 1 Low

Garden Route Shale Fynbos 3 2 3 High

Knysna Sand Fynbos 1 1 2 Low Southern Afrotemperate Forest 3 3 3 High



9.5.3.5 Inherent Visibility Analysis A visibility analysis was performed for the study area of the proposed development. A Digital Elevation Model (DEM) with a cell resolution of 90m was utilised together with a Geographic Information System (GIS) to determine the inherent visibility of each 90m cell. The visibility analysis considers the worst-case scenario, using line-of-sight i.e. ignoring trees and other structures, and is based on topography alone. The analysis performs a line-of-sight calculation from each cell within the study area to every other cell within a 10 kilometre radius. The visibility score of each cell is increased by 1 for every surrounding cell from which it is visible. This assists the process of identifying areas of high visibility and therefore high potential for visual impact. The following areas are indicated as areas of high visibility along the two proposed alignments, Westford Bridge North, Estuary Heights, Knysna Heights, Flenters and Robololo. 9.5.4 Visual Impacts for Routes, Intersections, Bridges, Underpasses and Toll Plazas

during Construction and Operational Phase. 9.5.4.1 Routes Proposed Route: Portions of the study area occur in a generally high scenic environment, visual impacts are anticipated to be generally high due to the high visual sensitivity of the receptors within the study area. The following areas will experience an intrusion on their views due to the presence of the proposed toll highway: Westford Bridge North, Estuary Heights, Riverglades, Kanonkop, Larenhill, Welbedacht, Knysna Heights, Paradise, Flenters, Robololo, Etembini and Concordia West. Short Route: Portions of the study area occur in a generally high scenic environment in particular, the Knysna River is a popular tourist attraction point. High visual impacts are anticipated within this area due to the proposed viaduct on the east side of the Knysna River, which forms part of the Short Route. The following residents will be affected, Estuary Heights, Riverglades, Kanonkop, Larenhill, Welbedacht, Knysna Heights, Paradise, Flenters, Robololo, Etembini, Concordia West. The reduced VAC over the Knysna River crossing magnifies the visibility of any structure crossing the river, resulting in high visual impacts and visual discontinuity. The existing N2 highway over the Knysna River is frequently utilised by tourists, therefore a high number of receptors are concentrated here. Significance statement for Visual Impacts of the Routes (Construction)

Effect

Impact Temporal


Impact Risk or



Proposed Route

Without Mitigation

Short term 1 Regional 3

Very severe 8 Definite 4 16

VERY HIGH -

With Mitigation

Short term 1 Regional 3 Severe 4 Definite 4 12 HIGH -

Short Route

Without Mitigation

Short term 1 Regional 3


VERY HIGH -

With Mitigation

Short term 1 Regional 3 Severe 4 Definite 4 12 HIGH -



Significance statement for the Visual Impacts of the Routes (Operational) Effect

Impact Temporal


Impact Risk or



Proposed Route

Without Mitigation


MODERATE -

With Mitigation

Long term 3 Localised 1 Slight 1 Probable 3 8 LOW -

Short Route

Without Mitigation


MODERATE -

With Mitigation


MODERATE -

9.5.4.2 Road Bridges/Intersections Large construction equipment is usually housed on site, as it cannot be relocated easily and at night is often lit up for security reasons. Construction equipment like cranes and other hoisting machinery is erected temporarily on site and sometimes for the entire duration of the construction period. Large equipment will be highly visible. Typical earthworks entail large areas of soil to be excavated, moved and piled. These soils are usually brightly coloured due to lack of organic matter, which creates a visual contrast with the surface soil. The disturbed landscape from the construction activities will take time to recover, thereby causing significant visual impact during operational phase due to lack of screening abilities. Eastford Interchange: The proposed Eastford Bridge is located in the middle of Eastford, Eastford Glen, Eastford Ridge and Estuary Heights residential areas. The residents of the above areas will be exposed visually to the proposed interchange structure. The residents are regarded as highly sensitive visual receptors. The residents of the above areas may be exposed to dust and other unsightly aspects of the construction activities. Salt River Interchange: The reduced VAC over the Salt River magnifies the visibility of any structure and construction activities that will occur. This will result in significant visual impacts to the surrounding residents of Eastford and the Salt River Valley. Uniondale/ R339 Road Bridge: The elevated profile of the proposed bridge will cause it to be visible to the nearby Khayalethu residents within a kilometre from the road bridge. The VAC will be increased or reduced depending on forest’s wood harvesting period. Mature forest plantations will provide significant screening whilst after harvesting screening will be reduced. Rheenendal & Brackenhill Interchange: The elevated profile of the proposed bridge will cause the construction activities of this bridge to be visible to the nearby farm residents within a kilometre from the interchange. The interchanges are located in a commercial forest environment; the visual impact can vary depending on the VAC provided by the commercial forest. The VAC will be low in cases were timber has been felled and higher for areas covered with mature trees. Springfield Interchange: The interchange is located in a commercial forest environment with no nearby settlements. No significant visual receptors will be affected by the construction of the toll plaza.



Significance statement for the Visual Impacts of the Road Bridges/Intersections (Construction)

Effect

Impact Temporal


Impact Risk or




Without Mitigation


Very severe 8 Probable 3 13 HIGH -

With Mitigation

Short term 1 Localised 1 Severe 4 Probable 3 9

MODERATE -

Salt River Interchange

Without Mitigation

Short term 1

Study area 2


With Mitigation

Short term 1

Study area 2 Severe 4 Probable 3 10

MODERATE -


Without Mitigation

Short term 1


MODERATE -

With Mitigation

Short term 1

Study area 2 Moderate 2 Definite 4 9

MODERATE -

Rheenendal and Brackenhill Interchanges

Without Mitigation

Short term 1 Study

area 2 Severe 4 Probable 3 10 MODERATE -

With Mitigation

Short term 1 Study

area 2 Moderate 2 Probable 3 8 MODERATE -




With Mitigation

Short term 1 Study

area 2 Severe 4 Definite 4 11 MODERATE -

Significance statement for the Visual Impacts for the Road Bridges/Interchanges (Operational)

Effect

Impact Temporal


Impact Risk or




Without Mitigation

Medium term 2 Localised 1


With Mitigation

Medium term 2 Localised 1 Severe 4 Probable 3 10 MODERATE_

Salt River Interchange

Without Mitigation

Long term 3

Study area 2 Severe 4 Probable 3 12 MODERATE_

With Mitigation

Long term 3

Study area 2 Moderate 2 Probable 3 10 MODERATE_


Without Mitigation

Short term 1

Study area 2 Severe 4 Definite 4 11 MODERATE_



Effect

Impact Temporal


Impact Risk or



With Mitigation

Short term 1

Study area 2 Moderate 2 Definite 4 9 MODERATE_

Rheenendal Interchanges

Without Mitigation

Short term 1

Study area 2 Severe 4

May occur 2 9 MODERATE_

With Mitigation

Short term 1


May occur 2 7 LOW -

Springfield and Brackenhill Interchanges Without

Mitigation Long term 3 Study

area 2 Severe 4 Probable 3 12 HIGH - With

Mitigation Long term 3 Study

area 2 Moderate 2 Probable 3 10 MODERATE_ 9.5.4.3 River Bridges and Viaduct Large construction equipment is usually housed on site as it cannot be relocated with ease and at night is lit up for security reasons. Construction equipment like cranes and other hoisting machinery is erected temporarily on site and sometimes for the entire duration of the construction period. Large equipment along with the construction activities will be visible to most residents located in Salt River valley, over a large area of Knysna River (affecting tourists) and tourist entering the town of Knysna in the case of the Viaduct. Typical earthworks entail large areas of soil being excavated, moved and stock piled. These soils are usually brightly coloured due to a lack of organic matter, which creates a visual contrast with the surface soil when they are stock piled and often causes dust. The windblown dust causes discolouration of the surrounding landscape and structures. Dust created from the construction activities will be highly visible and potentially affect views of sensitive visual receptors including tourists and residents. The reduced VAC over the Salt River crossing magnifies the visibility of any structures crossing over the river causing significant visual impacts and visual discontinuity. The proposed Salt River Bridges will affect the following viewers of Eastford, Knysna Heights, Eastford Glen, Narnia and Estuary Heights residential areas.

Bridge Type A, and C: These Bridge types have a similar visual appearance and structure; their visual impact will be the same. Bridge Type B: This Bridge type will have an increased visual impact on the viewers due to its elevated A-frame tower structure.

Knysna River Bridge: All three designs will have varying severity of visual impacts. Portions of study area occur in a generally high scenic environment in particular, the Knysna River is a popular tourist attraction, and therefore visual impacts are anticipated to be generally high due to the high visual sensitivity of the visual receptors within this locality. The reduced VAC over the Knysna River crossing magnifies the visibility of any structure crossing over the river, causing significant visual impacts and visual discontinuity.

Bridge Type A, B and C: Construction equipment will be visible to the surrounding tourist especially the ferry pick up points and road users along the Knysna River. The large earthworks and machinery will be visible over the Knysna River to residents and tourists.



Bridge Types A and B: These bridge structures will cause higher visual discontinuity due to the bulkiness of the bridge and embankment structures compared to bridge type C. A moderate visual envelope is anticipated due to the flat profile of the bridges types A and B. Bridge Type C: The Bridge’s visibility is increased by the caisson (tower) structures

White Bridge Viaduct: Portions of study area occurs in a generally high scenic environment, the Knysna River is frequently visited by tourist and forms a popular attraction point, therefore visual impacts are anticipated to be generally high due to concentration of visual receptors within this area. The reduced VAC over the Knysna River bridge crossing and ravine magnifies the visibility of the viaduct as it rises towards the Eastford toll plaza. The widening of the mud flats and additional piers will have a cumulative visual impact due to the already existing White Bridge over this section of the Knysna River. The rising viaduct over the Knysna River will lead to an increased visual discontinuity because of the viaduct, which will become a dominant feature over the White Bridge and ravine area. The visual character of the White Bridge will be altered from the existing familiar visual character that it is identified by, in this region. Significance statement for the Visual Impacts of the River Bridges (Construction)

Effect

Impact Temporal


Impact Risk or




Without Mitigation

Short term 1


MODERATE -

With Mitigation

Short term 1

Study area 2 Moderate 2 Probable 3 8

MODERATE -


Without Mitigation


Very Severe 8 Probable 3 14 HIGH -

With Mitigation


MODERATE -


Without Mitigation


MODERATE -

With Mitigation

Short term 1 Localised 2 Moderate 2 Probable 3 8

MODERATE -


Mitigation Short term 1 Localised 2 Severe 4 Probable 3 10

MODERATE -

With Mitigation


MODERATE -


Without Mitigation

Short term 1

Study area 2


With Mitigation

Short term 1


MODERATE -




Effect

Impact Temporal


Impact Risk or



Without Mitigation


MODERATE -

With Mitigation


MODERATE -


Without Mitigation


MODERATE -

With Mitigation

Short term 1 Localised 1 Moderate 2 Probable 3 7 LOW -


Without Mitigation

Medium term 2

Study area 2


VERY HIGH -

With Mitigation

Medium term 2

Study area 2


VERY HIGH -

Significance statement for the Visual Impacts of the River Bridges/Viaduct (Operational)

Effect

Impact Temporal


Impact Risk or





Study area 2 Severe 4 Probable 3 13 HIGH -

With Mitigation Permanent 4

Study area 2 Moderate 2 Probable 3 11

MODERATE -


Without Mitigation Permanent 4 Localised 2

Very Severe 8 Probable 3 17

VERY HIGH -

With Mitigation Permanent 4 Localised 2 Severe 4 Probable 3 13 HIGH -



With Mitigation Permanent 4 Localised 2 Moderate 2 Probable 3 11

MODERATE -


Mitigation Permanent 4 Localised 2 Severe 4 Probable 3 13 HIGH - With

Mitigation Permanent 4 Localised 2 Moderate 2 Probable 3 11 MODERATE

-

Knysna River Bridge Type A Without

Mitigation Permanent 4 Regional 3 Severe 4 Probable 3 14 HIGH - With

Mitigation Permanent 4 Regional 3 Moderate 2 Probable 3 12 HIGH -

Knysna River Bridge Type B Without

Mitigation Permanent 4 Regional 3 Severe 4 Probable 3 14 HIGH -



Effect

Impact Temporal


Impact Risk or



With Mitigation Permanent 4 Regional 3 Moderate 2 Probable 3 12 HIGH -


Without Mitigation Permanent 4 Regional 3

Very severe 8 Probable 3 18

VERY HIGH -

With Mitigation Permanent 4 Regional 3 Severe 4 Probable 3 14 HIGH -


Without Mitigation Long term 3 Regional 3

Very Severe 8 Definite 4 14 HIGH -

With Mitigation Long term 3


MODERATE -

9.5.4.4 Underpasses Lagoon Underpass and Concordia: The upgrading of portions of the roads that intersect with the highway underpass will alter the character of the local area through the introduction of hard paving surfaces and landscaping in these areas. Uniondale Underpass: The Uniondale road is already surfaced; very low visual impacts are anticipated at this point due to the high screening ability of the surrounding forestry plantations. Operational phase: Minimal and possibly negligible negative visual impacts are anticipated here Significance statement for Visual Impacts of the Underpasses (Construction)

Effect

Impact Temporal


Impact Risk or



Lagoon Underpass

Without Mitigation


May occur 2 8

MODERATE -

With Mitigation


May occur 2 6 LOW -

Concordia Underpass

Without Mitigation


May occur 2 8

MODERATE -

With Mitigation


May occur 2 6 LOW -

Significance statement for the Visual Impacts of the Underpasses (Operational)

Effect

Impact Temporal


Impact Risk or



Lagoon Underpass

Without Mitigation


With Mitigation




Effect

Impact Temporal


Impact Risk or



Concordia Underpass

Without Mitigation


With Mitigation


9.5.4.5 Toll Plazas The construction activities will alter the existing fabric and expose the underlying soils. Springfield Toll Plaza: No significant visual receptors will be affected by the construction of the toll plaza. The proposed structure will be screened by the existing high forest vegetation. The introduction of the toll plaza in this location will alter the existing forest character to an urban character. Groenvlei Toll Plaza: The construction of the toll plaza in this location will not affect any sensitive receptors including recreational user of Groenvlei Lake and Goukamma Nature Reserve, only motorist driving along the N2 will be exposed to the construction activities of the toll plaza in this location. The toll plaza is located at the valley bottom along which the N2 follows in addition the ridge along the south portions of the highway increases screening especially where forest vegetation is mature. Buffelsvermark Toll Plaza: The nearest visual receptors of Blackwater Farm are completely screened by the forest vegetation that surrounds this area. There is potential that residents located south of the toll plaza can experience views of the construction of the toll plaza, as they are located on a higher ground overlooking the proposed toll plaza. The inherent visibility analysis indicates the most visible areas as shaded in red, Eastford toll plaza is indicated as such an area. The Eastford toll plaza is located in a residential area; the visual impacts will therefore be high due to the high concentration of visual receptors in this area. The location of the toll plaza is generally elevated compared to the surrounding areas hence it is likely to visible over a large area affecting more visual receptors. Significance statement for Visual Impacts of the Toll Plazas (Construction)

Effect

Impact Temporal


Impact Risk or




Without Mitigation


MODERATE -

With Mitigation


MODERATE -

Eastford Toll Plaza

Without Mitigation

Short term 1

Study area 2


With Mitigation

Short term 1


MODERATE -




Effect

Impact Temporal


Impact Risk or



Without Mitigation



With Mitigation


MODERATE -



MODERATE -

With Mitigation


MODERATE -



MODERATE -

With Mitigation


MODERATE -

Significance statement for the Visual Impacts of the Toll Plazas (Operational)

Effect

Impact Temporal


Impact Risk or




Without Mitigation

Long term 3 Localised 1 Severe 4 Probable 3 11 MODERATE

- With

Mitigation Long term 3 Localised 1 Moderate 2 Probable 3 9 MODERATE

-

Eastford Toll Plaza Without

Mitigation Long term 3

Study area 2

Very severe 8 Probable 3 16

VERY HIGH -

With Mitigation


MODERATE -


Without Mitigation

Long term 3 Localised 1 Severe 4 Probable 3 11 MODERATE

- With


-


Mitigation Long term 3 Localised 1 Severe 4 Probable 3 11 MODERATE

- With


-


Mitigation Long term 3 Localised 1 Severe 4 Probable 3 11 MODERATE

- With


-



9.5.5 Potential Obtrusive Light Effects Lighting impacts are assessed in the operational phase and are limited to the toll plazas The high mounted floodlights, signal lights, and traffic lights at dusk. Eastford Toll Plaza: Floodlights will affect the surrounding residents of Simola and Salt River Valley. Significance statement for Obtrusive Light Effects of the Toll Plazas (Operational)

Effect

Impact Temporal


Impact Risk or




Without Mitigation

Long term 3 Localised 1 Slight 1

May occur 2 7 LOW -

With Mitigation


May occur 1 5 LOW -

Eastford Toll Plaza

Without Mitigation

Long term 3 Localised 1 Moderate 2

May occur 2 8

MODERATE -

With Mitigation


May occur 2 7 LOW -

Buffelsvermark Toll Plaza

Without Mitigation

Long term 3 Localised 1 Moderate 2

May occur 2 8

MODERATE -

With Mitigation


May occur 2 7 LOW -


Mitigation Long term 3 Localised 1 Moderate 2

May occur 2 8

MODERATE -

With Mitigation


May occur 2 7 LOW -


Mitigation Long term 3 Localised 1 Moderate 2 May


With Mitigation

Long term 3 Localised 1 Slight 1 May

occur 2 7 LOW - 9.5.6 Mitigation Methods The aim of mitigation is to reduce or alleviate the intrusive contrast between the proposed project components and activities, and the receiving landscape to a point where it is acceptable to visual and landscape receptors. Table 9.12 gives a summary of the Recommended Mitigation Measures and Application Area. General Proceed with construction of the highway and associated infrastructure during the off peak tourism season. The duration of the construction should be kept as short as possible to reduce severe landscape impacts, increasing the recovery chances of rehabilitated patches of land Where areas are going to be disturbed through the destruction of vegetation by, for example, the establishment of the construction camps, the vegetation occurring in the area to be disturbed must be salvaged and kept in a controlled environment such as a nursery, for future re-planting in the disturbed areas as a measure of rehabilitation.



Rehabilitate disturbed areas as soon as practically possible after disturbance; this should be done to restrict extended periods of exposed soil. Design Phase Treat structure facades with a mat paint or cladding that is similar to the prevailing colour of the surrounding landscape. Avoid very light and very dark coloured finishes that will increase colour contrast with the foreground and background. Always use mat paint and pastel colours which are subtle and resemble colours in the landscape. Visual impacts can be mitigated by cladding or painting the bridge structure with a colour that blends into the environment, unreflective and dull colours is usually recommended. In building structures, be sensitive towards the use of glass or materials with a high reflectivity in the infrastructure as to avoid glare from the shiny surfaces and to avoid visual discomfort for viewers. Use large roof overhangs to minimise glare from windows and mat finishes to reduce reflection. With regard to bridges, consider alternative bridge design that will have a reduced landscape footprint. Align the highway on the edge of the residential, cultivated fields, forest and any other land uses so as not to fragment large parcels of uniform landscapes. Locate the material stockyards as close to the highway alignment as practically possible to reduce the landscape footprint visual envelope of the different project components. A grouped arrangement will result in a concentrated disturbance footprint and the potential exists for the individual elements to screen each other from sensitive viewpoints. Screen planting should be introduced along the perimeter of the highway passing especially in areas with high sensitivity viewers. As a general good practice, screen planting should preferably be indigenous and comply with the Environmental Management Program (EMP). To increase the effectiveness of screen planting, screening berms can be constructed and vegetated. Construction Phase Manage stock-piled earth to reduce soil erosion and dust pollution by maintaining small mounds of stockpile as opposed to large stockpiles, which are often visible over large areas. Stockpile topsoil moved from clearing activities for rehabilitation purposes. Restrict disturbance over riverbanks and flood plains. Rehabilitate disturbed vegetation and prevent river water pollution to avoid downstream impacts and reduce additional destruction to the Knysna lagoon Locate construction camps and stockyards out of the visual field of highly sensitive visual receptors. Choose sites that are close to an existing clump of trees or inconspicuous sites. Utilise the existing screening capacity of the site and improve it by enclosing the construction site and stockyards with a dark green or khaki brown shade. Construction equipment should be strategically placed to avoid blocking popular tourist views and vistas and removed when not required on site. Construction camp establishment should avoid landscape modifications like tree cutting, grading and levelling of the landscape. Retain the existing vegetation cover of the site through selective clearing. Where practical, protect existing vegetation clumps during the construction phase in order to facilitate screening during construction and operational phases. Visual screening of the White Bridge viaduct will not have significant mitigation in this situation.



Keep the construction sites and camps neat, clean and organised in order to present a general tidy appearance; Remove rubble and other building rubbish off site as soon as possible or place it in containers in order to keep the construction site free from additional unsightly elements; Pave roads where relative high volumes of traffic are expected, to minimise dust generation and potential unsightly discoloration of vegetation along roads. Alternatively, other dust suppression techniques should be implemented especially on windy days; Operational Phase The mitigation methods for the operational phase are largely the same as are mentioned for the construction phase. Where the mitigation methods differ is in monitoring the new vegetation establishments for three months to make sure that it establishes successfully, especially in areas were vegetation is established for screening purposes. In addition, monitor water quality and any permanent damage from construction activity. Ecological damage to the river ecosystem will be almost impossible to mitigate. Areas of Cut and Fill To minimise the visual impact of the cut and fill areas, the slopes should be as gradual as possible. A slope of 1:2 has the potential of soil erosion during heavy rain events, hampering the growth of the recovering vegetation. Slopes of 1:2, 5 or 1:3 are preferred. On steeper slopes, more than (1:2) make use of retaining blocks that allow for vegetation establishment. Hydro-seeding must be undertaken on slopes with soft material (soils, residual and transported) as soon as possible; The success of hydro-seeding must be monitored over a period of 3 years and be repeated in areas of low success; and The use of a combination of gabions and vegetation cover on steep cuts is encouraged. Light Impacts Reducing the number of light sources on the bridges will assist with a reduction of light impacts especially during night-time. Motorists will make use of the signal and flood lights; this is considered as part of the operation of the toll plaza which neither a negative or positive impact Avoid light trespass and glare originating from external light sources. Fit “full cut-off” luminaries to limit the amount of light trespass and spillage so as to control light output and restrict glare (Shaflik, 1997) (see Figure 9.2). If construction is necessary during night time, light sources should be directed away from residents and roads so as to prevent obtrusive lighting. When vertical structures or surfaces are lit such as building facades or bridge masts, install a down light luminaire. If the only alternative is to up-light the element, the correct luminaire must be fitted to avoid light spillage. Avoid over-illumination of outdoor spaces (see Figure 9.3). Generally, low-pressure sodium lights are regarded as highly energy efficient and suitable for security lighting. Light impacts can easily be mitigated by installing appropriate lighting that does not spill light. Lighting should be minimised and installed where necessary around the toll plaza.



Strategically introduce screen planting around buildings and the perimeter fence so as to reduce the adverse affect of obtrusive lighting. Screen walls can be installed along the perimeter of the resident’s yards adjacent the toll plaza It is assumed that most of the vehicle lights will be screened by the parapet structure along the entire route of the toll highway. Vehicle headlights are anticipated to cause a negligible level of glare. The visibility analysis indicates that the floodlights from the Buffelsvermark toll plaza within two kilometres will affect no visual receptors. Visual impacts are generally significant for receptors within 1 to 2 kilometres from the light source, although the Black Waters Farm is located within 1.5 kilometres, they will not be affected, as they are located in a valley and surrounded by dense forest vegetation that helps to screen potential light impacts.

Figure 9.2: Luminaire fixtures (Shaflik, 1997)

Figure 9.3: Directing outdoor luminaries (ILE, 2005)



Adjacent Land Uses Where the highway is in close proximity to Eastford and other residential areas, care must be taken to retain a sufficient visual barrier (screen planting) to minimise the effect on visitors to the highway and its components. Table 9.12: Recommended Mitigation Measures and Application Area

Item Sections Affected Recommended Mitigation Measure Area of

Application

1 Road Reserve • Rehabilitate disturbed areas with local indigenous plants

and appropriate high tree species where screening is required.

Along entire Proposed Routes and existing N2

2 River Crossings

• When constructing piles for the bridge, temporarily detain water flow to allow settling of mud in order to prevent further downstream impacts;

• Design a bridge structure that is supported on anchor points resting on the bank vs. piers in the sensitive flood plains of the Knysna River/ Lagoon or river; and

• Reduce embankment structure footprint and increase water flow by incorporating culverts.

Knysna River and Salt River

3 Interchanges,

Underpasses and other

intersections

• Establish screen planting , so as to screen structures and thereby increase surrounding visual absorption capacity;

• Design and placement guidelines for structures and infrastructure i.e. signage, communication, lighting etc. to consider:

o Use of appropriate materials; o Avoid positioning on ridgelines; o Massing, i.e. cluster activities where possible;

• Appropriate setbacks from adjacent sensitive land uses, especially residential and tourism;

• Building structure should have modest scale, height and form of simple rectangular nature;

• Structures to be as ‘transparent’ as possible to ‘melt’ / integrate into the landscape- make use of slender structures;

• Signage and other infrastructure, e.g. communication leading up to and at plazas to be kept to a minimum;

• Lighting to be kept to a minimum, to minimise light pollution and intrusion especially into private properties adjacent; and

• The mitigation of light pollution / intrusion through the planting of high trees in affected visual receptor’s gardens and road reserves.

Along entire Proposed Routes and existing N2

4

Toll Plazas

• Adjacent to / in close proximity of existing development versus placement in a natural (un-built) landscape except for residential and tourist developments;

• Toll plaza to consider positioning of existing high tree breaks, avenues, etc. which provide visual absorption;

o Planting appropriate high trees, so as to screen structures and thereby increase surrounding visual absorption capacity;

• Landscaping of medians / islands leading up to Toll Plaza to increase vegetative cover;

• Design and placement guidelines for structures and infrastructure i.e. signage, communication, lighting etc. to consider:

o Use of appropriate materials; o Massing, i.e. cluster activities where

Groenvlei, Buffelsvermark, Eastford, and

Springfield Toll Plazas



Item Sections Affected Recommended Mitigation Measure Area of

Application possible;

o Appropriate setbacks from adjacent uses, especially residential and tourism;

o Modest scale, height and form of simple rectangular nature;

o Structures to be as ‘transparent’ as possible to ‘melt’ into the landscape;

o Signage and other infrastructure, e.g. communication leading up to and at plazas to be kept to a minimum;

o Signage and other infrastructural elements be uniform as far as possible; and

o Lighting to be kept to a minimum, to minimise light pollution and intrusion especially into private properties adjacent.

5 Residential and Tourist Areas

Mitigation of visual impact through landscaping and other visual barriers:

• Planted earth berms in selected areas; • Planting of appropriate high trees within road

reserve and / or private plot; and or • Residential edge treatment e.g. perimeter walls

(review regulation on maximum allowable height for residential property perimeter walls adjacent the road corridor).

Mitigation of visual impact of light pollution / intrusion through:

• consideration at detail design stage; • use of reflectors on side positioned street lights to

direct light onto road; • planting of high trees in gardens or in road reserve;

and • Implementation of noise barriers on the freeway,

which would provide a visual barrier. It may however be necessary to investigate special mitigation measures at detail design stage for properties immediately affected/adjacent to toll highway.

Eastford Paradise/West Hill and , Khayalethu, Karatara and other residential areas

occurring along the proposed

alignments

9.5.7 Conclusions of Landscape and Visual Assessment The most severe landscape impacts are anticipated to occur in the construction phase along the alternative alignments, over undeveloped landscapes in the central section of the Highway where large amounts of clearing are expected to occur adjacent to the residential properties of Eastford, West Hill, and the informal residents north of Knysna CBD (Concordia area), and on conserved forest areas around the Concordia underpass (see Table 9.13 for a summary of landscape and visual impacts). In the western section of the highway there will also be significant landscape impacts over the sensitive Knysna River flood plain landscape for both routes. The most severe visual impacts are anticipated to occur in the operational phase, attributed mainly to the permanence of the finished elements of the toll highway. Areas of high visual impact include the Knysna River valley in the western section of the Highway, and Salt River valley and Eastford areas in the central section (see Table 9.13).



Due to the difference in length of the two alternatives, a simple sum of impacts as comparative analysis will tend to be biased towards the Short Route as the preferred alternative. A different approach focused on the most critical impacts is required when selecting the most appropriate alternative. Below are the critical landscape and visual impacts associated with the Proposed Route and the Short Route. Short Route - Critical Impacts Landscape Impacts

• Landscape impacts associated with the viaduct traversing over red data species on the ravine leading to the Eastford interchange.

Visual Impacts • Cumulative visual and landscape impacts of the additional White bridge and viaduct; • Possible change in visual character of the well known White Bridge; • Low VAC (Visual Absorbance Capacity) over the Knysna River, White bridge crossing; • High number of visual receptors occurring around the White Bridge; • High visual impacts on tourists using the existing N2 travelling into and out of Knysna town;

and • High visual impacts in the construction phase on recreational users of the Knysna River

and Lagoon area. Proposed Route - Critical Impacts Landscape Impacts

• The Proposed Route traverses large areas of undeveloped and undisturbed landscape from Buffels Bay intersection to the Eastford residential area. This new road portion will require a significant amount of clearing, cut and fill to accommodate the new road in this section.

Visual Impacts • High visual impact arising from the construction of a bridge crossing over the Knysna River

next to the Red Bridge. Due to the fewer critical impacts associated with the Proposed Route, it is the most preferred alternative route for the N2 Toll Highway; provided the mitigation measures listed in Section10Error! Reference source not found. of the Specialist Volume are implemented, the landscape and visual impacts of the toll highway can be mitigated to acceptable levels. Figure 9.4 shows an example of the proposed mitigation along the highway. There were no landscape or visual impacts associated with the Do Nothing option.

Knysna Environmental Impact Report– April 2009


Table 9.13: Summary of Landscape and Visual Impacts Landscape Impacts Visual Impacts

Construction Phase Operational Phase Construction Phase Operational Phase

Issue/Impact

Without With mitigation Without With mitigation Without With mitigation Without With mitigation Proposed High - Moderate - Moderate - Moderate - Very high - Moderate - Moderate - Low - Short High - High - Moderate - Moderate - Very high - High - Moderate - Moderate - Rheenendal interchange - PR High - Moderate - High - Moderate - Moderate - Moderate - Low - Low - Eastford interchange Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - High - Moderate - Uniondal/R339 Road bridge Moderate - Moderate - High - Moderate - High - Moderate - Moderate - Moderate - Saltriver interchange Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - Springfield Interchange High - Moderate – High - Moderate – Moderate - Moderate - Moderate - Low - Brackenhill Interchange High - Moderate – High - Moderate – Moderate - Moderate - Moderate - Low - Estuary bridges Knysna Proposed Bridge A High - Moderate - Moderate - Moderate - High - Moderate - High - High - Knysna Proposed Bridge B Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - High - High - Knysna Proposed Bridge C Moderate - Low - Moderate - Low - Moderate - Moderate - Very high - High - White Bridge viaduct (SR) High - Moderate - Very high - High - High - Moderate - High - Moderate - Saltriver bridges Saltriver bridge A High - Moderate - Moderate - Moderate - Moderate - Moderate - High - Moderate - Saltriver bridge B Moderate - Moderate - Moderate - Moderate - High - Moderate - Very high - High - Saltriver bridge C Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - High - Moderate - Saltriver bridge D High - Moderate - Moderate - Moderate - Moderate - Moderate - High - Moderate - Underpasses Lagoon underpass Moderate - Low - Low - Low - Moderate - Low - Low - Low - Concordia underpass Moderate - Low - Low - Low - Moderate - Low - Low - Low - Uniondale Underpass Low - Low - Low - Low - Low - Low - Low - Low - Toll Plazas Buffelsvermark Toll Plaza High - Moderate - Moderate - Moderate - High - High - Moderate - Low - Groenvlei Toll Plaza Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - Moderate - Low - Eastford Toll Plaza - SR High - Moderate - High - Moderate - High - Moderate - Very high - Moderate - Springfield Toll Plaza High - Moderate - High - Moderate - High - Moderate - High - Moderate -



Landscape Impacts Visual Impacts Construction Phase Operational Phase Construction Phase Operational Phase

Issue/Impact

Without With mitigation Without With mitigation Without With mitigation Without With mitigation Brackenhill Toll Plaza High - Moderate - High - Moderate - High - Moderate - High - Moderate - Obtrusive lighting impacts of Toll Plazas Buffelsvermark Toll Plaza N/A N/A N/A N/A N/A N/A Moderate - Low - Groenvlei Toll Plaza N/A N/A N/A N/A N/A N/A Low - Low - Eastford Toll Plaza N/A N/A N/A N/A N/A N/A Moderate - Low - Springfield Toll Plaza N/A N/A N/A N/A N/A N/A Moderate - Low - Brackenhill Toll Plaza



Figure 9.4: Proposed mitigation along the highway



9.6 Noise Impacts The exposure to noise from road traffic at any observation/receiver location is a combination of numerous different yet interrelating factors. These may be categorised as follows:

• Noise source – how it is produced and how the level of noise emitted can be reduced.

• Propagation path – how topography, intervening structures and the atmosphere influence the reduction in level of noise between the noise source and receiver location.

• Receiver – the factors at the receiver location that influence the level of noise received and the resulting impact of the noise on the receiver.

Noise generated by road traffic consists predominantly of two independent components that are predictable and that can therefore be incorporated in road noise calculations:

1. Propulsion noise produced by the driveline - engine, exhaust, cooling system, gearbox, axle.

2. Rolling noise generated by the interaction of the tyres with the road surface and which accounts for over 80% of the noise produced by road traffic.

Knysna forms part of the renowned Garden Route sought after for recreation, holiday property investment and visited by local and international tourists for its unique natural beauty and expectations of its peace, tranquillity and quiet typically quantified by a measured daytime LAeq,T (the equivalent continuous day/night rating level of noise) = 36 dBA away from road traffic (refer to Section 11.6 in Specialist Volume Part 2). The assessment of road noise in this project may therefore not be limited to the impact thereof only on residential communities but must include consideration of its impact on the natural beauty and solitude of the area in its widest concept. The overriding influence of the road surface texture on noise emanating from road traffic is presented in section 9.6.1.1. The basis upon which to predict the levels of noise on land adjacent to a road – in the absence of noise mitigation – therefore depends on the selection of the particular road surface. Many disparate road surfaces are used on freeways and urban roads throughout South Africa with respective noise levels at a reference distance of 10 m differing in excess of 10 dB for the different surfaces. This presented no clear guide for the selection of an “average” surface to be used as a datum for this study. The calculation of the LR,dn noise level contours appearing in this study – in the absence of noise mitigation - utilised the acoustical properties of a Continuously Graded Asphalt (CGA) surface as a datum in line with the author’s international colleagues. The LAeq,T contours appearing in this chapter could thus be readily extrapolated to other road surfaces for which reference measurements were available in South Africa and to other new road surfaces based on the same datum. The Physical and acoustical properties of a CGA and other surfaces appear in section 9.6.1.1. It is noted that road noise emanating from a CGA surface is lower than all surface seals and Ultra Thin Friction Courses (UTFC) measured to date by the author in this country. The latter surfaces appear more frequently on many freeways due to their improved skid resistance, hence safety, compared to a CGA surface. However, the details and benefits of low-noise friction courses appear in section 9.6.1.1. The calculated LR,dn for the various sections of the proposed N2 Toll Highway including proposed interchanges and associated link roads are all displayed in the form of LR,dn contours at 5 dB intervals overlaid onto Google Earth aerial photographs of the respective sections. The top of each Figure faces North. The noise contours only portray the LR,dn due to the proposed roads and do not include the contribution of noise from existing roads or other noise sources.



The fill colours between contiguous contours are shown in the colour scale in Figure 9.5. Thus, the colour yellow depicts the land area on which the LR,dn will range between 50 dBA and 55 dBA. Rendering the contour overlays transparent may cause difficulty in distinguishing the colour changes. The LR,dn contour values (in dBA) have therefore been indicated in many places by means of black numerals on a white circular background.

Figure 9.5: LR,dn colour scale used for all predicted noise contours Where ambient noise levels were measured for an extended duration the recorded LAeq,T values (in dBA) are displayed in white on a black square background at the particular measurement location. The entire route was divided into four sections:

1. The western section between Groenvlei and east of the Knysna River. 2. The central section including the alternative Eastford and Salt River Interchanges. 3. The section of the highway east of the Salt River to west of the Uniondale Interchange. 4. The eastern section of the “Proposed” route from 1km west of the Uniondale Interchange to

Bracken Hill with its associated link road from Uniondale to Springfield and the “Short” route between Uniondale Interchange and Springfield.

9.6.1 Mitigation Methods 9.6.1.1 Influence of road surface texture on the production of rolling noise The road surface texture has an overriding influence on the production of rolling noise. The terminology used to describe road surface texture and its effects on noise emission is outlined in Figure 9.6. a Contact patch length of a tyre with the road surface – 100 to 110 mm for passenger vehicles λ Road texture wavelength – distance between adjacent peaks of surface texture d Vertical displacement of the tyre wall within contact patch

LR,dn dBA



h Road texture depth

Figure 9.6: Road surface texture descriptors related to tyre contact patch length An analysis of the frequency content of road noise provides valuable insight into the relative contribution of rolling noise emanating from different road surfaces compared to engine/driveline noise [Jongens, 2008]. A series of road noise measurements were recently conducted along the N2 between George and the Knysna River [Jongens Keet Associates, 2008]. Of relevance to the present project are the results of LAeq,T measurements after resurfacing large sections of the N2 up to the Knysna River with a Triple Seal friction course. An LAeq,T of 71 dBA was measured both at the western end of the Swartvlei causeway and at Groenvlei; the same location proposed for the alternative mainline Toll Plaza at the western end of the Toll Highway. It is understood that Triple Seal was chosen in the belief that it would produce a low level of road noise due to the use of 8 mm stone aggregate as top layer between 19 mm stone. The aggregate size is smaller compared to the surfaces displayed in Figure 9.7. However, due to the surface not being rolled smooth, it presents a large texture wavelength and texture depth with, in addition, the sharp edges of the stone impacting on the tyre. Unfortunately Triple Seal produces amongst the highest levels of rolling noise.

Macrotexture

Megatexture

Unevenness

d

λ << a d << h

λ ≈ a d ≈ h

λ >> a d << h

h

λ Low tyre/road noise exterior

and interior of vehicle Maximum tyre vibration hence maximum noise production exterior and interior of vehicle; traveller discomfort Low noise production; traveller discomfort

a

λ

(Descornet & Sandberg, ISO 13473-5)

Effect of texture



Figure 9.7: Cape Seal (left) and Ultra Thin Friction Course (right) with 1/3rd octave sound level spectrum (dBA) measured at 10m from the road edge. Traffic flow: 100 km/hr, 650 veh/h, 5% heavy duty vehicles. By comparison Figure 9.8 displays the noise levels measured 10 m from a smooth, well rolled Continuously Graded Asphalt (CGA) surface close to the Rademacher Nursery east of George. Unfortunately dissimilar traffic flow conditions could not enable a direct comparison with the previous surfaces. The results are for a mean speed of 80 km/h; 15% heavy-duty vehicles and 560 vehicles per hour. Apparent is a virtually zero texture wavelength and texture depth that minimises the vibrations imparted into the tyres and thus the noise produced by the tyre walls.

LAeq,T = 76 dBA LAeq,T = 69 dBA

0

10

20

30

40

50

60

70

80

31.5 63 125 250 500 1000 2000 4000 8000

Frequency, Hz

A-w

eigh

ted

Soun

d Pr

essu

re L

evel

, dB

A

UTFC 69dBA Cape Seal 76dBA

64444444744444448 Rolling noise 64748

Engine/driveline noise

D=15dB D =22dB

69dBA

62dBA 47dBA

1000 HZ



Figure 9.8: Continuously Graded Asphalt with 1/3rd octave sound level spectrum (dBA) at 10m. Traffic flow: 80 km/h, 560 veh/h, 15% heavy duty veh.

It is stressed that the acoustical properties of a smooth Continuously Graded Asphalt surface have been used in the calculation of the noise level contour diagrams in this study without noise mitigation. Thus, were any “seal” or other surface discussed in the previous paragraphs to be used all noise level contour values shown would need to be increased by between 3 dB and 10 dB depending on the particular surface. Figure 9.9 shows a photograph of a 2 to 3cm thick, well rolled, porous Ultra Thin Friction Course comprising aggregates of 6mm or less and with a rubber-bitumen binder. The rolling process ensures that the flat faces of the stone aggregate come into contact with the tyre. It is presents a similar reduction in tyre generated noise as a CGA surface. But the additional reduction in noise is due to the porous surface eliminating the generation of air-pumping noise and effectively removing half of the “horn” that would amplify the emitted noise. Note the similarity when cupping your hands around your mouth to project you voice and then removing one of your hands. It is a durable surface providing good skid resistance and used extensively in The Netherlands. The surface is so quiet that the author was unaware of an approaching vehicle while photographing the surface!

0

10

20

30

40

50

60

70

80

90

31.5 63 125 250 500 1000 2000 4000 8000

Frequency, Hz

A-w

eigh

ted

Soun

d Pr

essu

re L

evel

, dB

A

CGA 66dBA

57 dBA 46 dBA

D=11dB

1250 Hz

LAeq,T = 66dBA



This low-noise UTFC has not yet been applied to roads in South Africa. Comparative noise measurements conducted in The Netherlands indicate that a reduction in LAeq,T of approximately 5 dB compared to the CGA surface shown in Figure 9.8 could be expected.

Figure 9.9: Thin, low-noise, porous, rubber-bitumen friction course The level of noise from a road decreases by 3dB for every doubling of distance of the observer from the road. Thus, a reduction of 5dB at source due to a low-noise surface is equivalent to what an observer would experience at a threefold increase in distance from a road with a CGA surface. Cost comparison of low-noise, porous, rubber bitumen friction course The resurfacing of existing roads with Ultra Thin Friction Courses is becoming more common. Recently the N2 Freeway in the vicinity of the N2 Gateway housing project outside Cape Town was resurfaced with a 3 cm thick, open-grade wearing course containing 13 mm aggregate. This unfortunately resulted in a noisier surface than that which it replaced due to the large aggregate size and spacing of the aggregates (large texture wavelength). The author enquired from the road builder who had laid the above surface and from a major supplier of road materials what the cost would be of laying the low-noise, porous, rubber-bitumen road surface illustrated in Figure 9.9 [PC 2007]. The answer: 1 Rand less per square metre of road surface compared to the existing surface! Indeed, the cost of ensuring watertight integrity of the base layer was not included. The rubber-bitumen binder provides improved durability compared to many local seal surfaces. Thus, a substantial decrease in the exposure to noise from our roads can be achieved over large areas of land and hence on thousands of residences at a lower cost than friction courses used to date in this country. The author hopes that the extensive discussion in this chapter of the relationship between road surface texture and the production of road noise and the contents of referenced literature will be utilised in the future choice of road surfaces so as to minimise road noise in general and, in particular, the present project.

Microflex 0/6 Porosity 15% Thickness 2 - 3cm



9.6.1.2 Noise Barriers In instances where highways and other roads with large traffic volumes pass close to residential suburbs the “quietest” road surface would be insufficient to ensure compliance with legislated or recommended levels. Additional noise mitigation measures in the form of high noise barriers would be required. A noise barrier is any continuous object, without apertures, with a minimum mass of 24 kilogram per square metre of surface area. Typical barriers include earth berms; brick walls; buildings; metal or 10mm thick Perspex or glass sheeting; or any combination of these. Noise barriers are only effective against road traffic if their effective height is at least 2 m and they are positioned close to the road edge. “Effective” height is the vertical distance between where the line-of-sight joining noise source and receiver intersects a barrier and the top of the barrier. This is illustrated in Figure 9.10. The source height for passenger vehicles is assumed to be 0,5 m above the road surface. However, the outlet of the exhaust of some heavy-duty vehicles is located some 2m above road level. In many countries throughout the world, where busy roads traverse densely populated areas, extensive use is made of noise barriers that are typically 5 to 7 m high and even 11 m high along some routes where residences and road are at the same elevation. These tall barriers are generally used in combination with low-noise road surfaces in order to achieve sufficient road noise mitigation on noise sensitive land close to the road. The required height and lateral extent are dependent on the topography and relative elevations of road and adjacent noise sensitive land. Noise barriers are only effective in reducing the level of noise at residences located close to the barrier. Sound diffracts, or “spills”, over the top of a barrier. Beyond several tens of metres the reduction of noise is increasingly due to the increased distance and less due to the barrier. In addition, under certain meteorological conditions, sound propagating in the atmosphere ”bends” down towards the earth as illustrated in Figure 9.11. This condition generally prevails during wind-still conditions just before sunrise and after sunset and for light winds blowing in a direction from noise source to receiver. Trees and shrubs provide no meaningful reduction of sound from road traffic noise. They do, however, provide a psychological benefit by reducing the visual distraction of passing traffic.



Figure 9.10: Effectiveness of barriers for different topographical situations

Figure 9.11: Noise barriers are only effective for residences close to the barrier

Effective barrier height benefiting ground floor window only

Lines of sight Upstairs window: No reduction in noise level Ground floor window: Some reduction in noise

a. Residence & road at same elevation

Upstairs window: No reduction in noise level Ground floor window: Some reduction in noise

Lines of sight

Effective barrier height benefiting ground floor window only

b. Residence above road - requires very high wall for any noise reduction

c. Residence below road – good noise reduction even for low wall

Noise reduction for upstairs & ground floor windows

Lines of sight

Effective barrier height benefiting upstairs window



9.6.1.3 Reduction in vehicle speed For a constant number of vehicles per hour a reduction in mean traffic speed from 120 to 60 km/hr causes a reduction in LAeq,T of 6 dB at receiver location for traffic containing up to 3% heavy-duty vehicles and a reduction of 5 dB for traffic containing between 4 and 14% heavy-duty vehicles. These both represent significant differences in LAeq,T and substantiate the need to implement and enforce the 60 km/hr speed limit on roads traversing suburban areas. 9.6.1.4 Separation distance Doubling the distance between a road and a listener results in a 3 dB reduction in noise level. In terms of human’s response to sound this difference is insignificant. Doubling the new distance results in a further 3 dB reduction in noise level. The total reduction of 6 dB is perceived by humans as a significant difference in “loudness”. The use of separation distance could thus be very costly in terms of land use unless the intervening land were zoned for commercial or other less noise sensitive use thereby creating noise buffer zones and additional noise screening by the intervening buildings for noise sensitive land further removed from the road. 9.6.1.5 Sound insulation of dwellings The installation of “double glazing” is often suggested as a noise mitigation option. Double glazing, with small separation between panes, is primarily utilised for thermal insulation in colder climatic regions, and is less tenable in the warm South African climate where windows are traditionally left open. Noise reduction would require thick, laminated glass in sealed frames accompanied by the installation of costly fresh-air ventilation systems with appropriate noise attenuation. In addition, sound insulation of buildings will not resolve the problem of noise intruding into private gardens and onto outdoor educational and recreational spaces. 9.6.1.6 Resettlement of people It has been proposed that resettlement of people should be considered as a noise mitigation option. It would seem logical that those settlements – formal or informal - situated within the proposed road reserve will need to be relocated. South Africa comprises large tracts of land where it appears difficult for any authority to control the ordered settlement of people in those areas. Thus, even if it was decided to resettle people of informal settlements in the vicinity of the proposed Toll Road there appears to be no effective mechanism in place that will ensure that new informal settlements will not sprout in the immediate vicinity of the new road. It is therefore questioned whether the resettlement proposal – outside of the road reserve - is practically viable. 9.6.2 Predicted Noise Impacts for the various sections of routes 9.6.2.1 Western Section (Groenvlei to Knysna River) Mitigation method: Low noise road surface The western section of the Proposed Route involves the use of the existing road from Groenvlei to Buffelsvermaak, and then the construction of an entirely new road from Buffelsvermaak to the Knysna River that would pass through a largely farming area until beyond the proposed new Rheenendal Interchange when, upon descending towards the western bank of the river it would pass close to an hotel, a private nature reserve, other tourist accommodation and private residences along the western banks of the Knysna river before crossing over a new bridge. This



section includes residential land on the eastern side of the Knysna River until west of the alternative proposed Eastford Interchange. The aerial survey data did not include the land along the existing N2 between Buffels Vermaak and the start of the White Bridge. A direct quantitative comparison of the two routes west of the Rheenendal Road and the section of the existing road between the existing Rheenendal intersection and the White Bridge could therefore not be made.

Along the Proposed Route there would be a very significant increase in LR,dn in excess of 10 dB above measured existing levels of 36 and 38 dBA along large areas of rural as well as rural residential land and in excess of 15 dB within 500 m of the Proposed Route. On residential land overlooking the Knysna River the affected area would extend more than 1000 m from both sides of the road. If traffic no longer flowed on the 2 km section of the existing N2 west of the existing Rheenendal intersection the LR,dn along that section would reduce significantly representing a substantial to very substantial benefit on land adjacent to the road. However, the area of affected land would be small compared to the area of land to be severely impacted upon by the Proposed Route up to the Knysna River. The NCR limit of 65 dBA would be confined to land extending approximately 60 m from the road. In terms of the NCR noise mitigation procedures would be required to reduce the noise levels within this distance to below 65 dBA.

After mitigation, the LR,dn values would reduce by approximately 5 dB throughout the area shown. However, the measured existing levels of 36 dBA on most of the land would still be exceeded. The LR,dn would still exceed the existing level of 36 dBA on large areas of rural/farm land by between 2 dB and 27 dB with a severity of impact ranging from Slight to Very Severe. On residential land and tourist accommodation overlooking the Knysna River the LR,dn would still exceed the measured existing levels by 10 dB within 400 m and 15 dB within 250 m from the route with a severity of impact ranging from Moderate to Severe. There would be a reduction in LR,dn of 10 dB on the residential land west of the Knysna River overlooking the White Bridge. However, with the contribution of noise emanating from reduced traffic flow on the White Bridge the estimated reduction would be limited to 5 dB with an associated Slight benefit. The NCR limit of 65 dBA would be confined to land within 50 m of the N2. In terms of the NCR noise mitigation procedures, such as noise barriers, would be required to reduce the noise levels within this distance to below 65 dBA.

Along the western section of the Short Route, there would be no increase in LR,dn and thus no noise impact on land in the upper half of Figure 9.12, except for the Eastford plateau area shown at the right of the Figure. The LR,dn on the residential land west of the Knysna River overlooking the White Bridge would be up to 5 dB higher than existing levels with an associated Severity of noise impact ranging between Slight for the furthest residences to Severe for the nearest residences to the White Bridge. This would be entirely due to the increase in traffic volume and mean speed compared to the existing speed limit of 80 km/h on the bridge (refer to the discussion in section 11.6.1 in Specialist Volume Part 2). After mitigation, the predictions indicate that with a low-noise surface the LR,dn would be the same as existing levels on the residential land overlooking the White Bridge ranging between Negligible to Moderate dependent on the distance from the White Bridge. There would thus be No noise impact. Similarly, there would be no increase in LR,dn and No noise impact on all land shown on the upper half of Figure 9.13 excluding land on the Eastford plateau



Figure 9.12: Predicted LR,dn for the “Short” route via the White Bridge

Figure 9.13: Predicted LR,dn for the “Short” route via the White Bridge – with low-noise road surface

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For the Do Nothing option, the section of the route would be the same as the proposed Short Route up until the eastern end of the White Bridge. The existing speed limits varying from 100 km/h in the west to 80 km/h on the bridge were assumed to remain in place and that the road surface had been rehabilitated with a CGA surface. There would be a 1 dB increase in LR,dn due the increase in traffic volume between 2008 and 2013 that would occur along the whole section of the route. The associated severity of impact would be between Negligible to Moderate dependent on the distance from the White Bridge. Were the surface of the N2 on the bridge to be rehabilitated with a low-noise road surface (mitigation), it was estimated that there would be a reduction in LR,dn of the order of 6 to 9 dB, compared to the existing surface including the effects of increased traffic flow in 2013. The associated impact on the residential land overlooking the White Bridge would range between Negligible and Slight. Significance statement for the western section of the Highway between Groenvlei and the Knysna River



Risk or Likelihood

Total Score


Proposed Route Without

Mitigation permanent 4 Study Area 2 Very Severe 8 Definite 4 18 VERY HIGH -

With Mitigation permanent 4 Study Area 2 Severe 4 Definite 4 14 HIGH -

Short Route Without

Mitigation permanent 4 Study Area 2 Severe 4 Definite 4 14 HIGH -

With Mitigation permanent 4 Study Area 2 Moderate 2 Probable 3 11 MODERATE

- Do Nothing Option

Without Mitigation permanent 4 Study Area 2 Moderate 2 Probable 3 11 MODERATE

- With

Mitigation permanent 4 Study Area 2 Slight 1 Probable 3 10 MODERATE -

9.6.2.2 Existing N2 in the vicinity of Knysna: Comparative assessment of existing and

predicted future noise impacts Mitigation method: Low noise road surface Noise is generally assessed in terms of the day/night rating level, LR,dn, of noise. Due to the high percentage of heavy-duty traffic passing in close proximity to residences, tourist accommodation and businesses through Knysna during night-time together with the availability of accurate hourly traffic flow data through Knysna containing these percentages it enabled a comparison of assessments of the existing and predicted future night-time rating levels, LReq,n, of noise to be made for this part of the study area. It was considered in section 11.6.1 in Specialist Volume Part 2 that the night-time LReq,n provided a closer correlation of the quantitative values with the subjective responses received from residents and businesses located close to the Main Road (N2) passing through Knysna. Assessment in terms of the night-time LReq,n is therefore included and considered more representative than LR,dn for the assessment of noise impact in this chapter.



Existing noise impact: In section 11.6.1 in Specialist Volume Part 2 the calculated existing LR,dn at the closest residences to the Knysna Main Road within and west of the CBD was 65 dBA. In terms of the day/night LR,dn the existing Severity of impact of noise is Moderate. However, the existing impact of the 61 dBA night-time LReq,n is Very Severe. Due to the controlled intersections the variation in noise level due to the stop-start traffic flow conditions would render the noise more noticeable and thus more intrusive within the CBD. The estimated existing LR,dn at residential boundaries 15 m from the N2 east of the CBD is 63 dBA with an associated Moderate impact. The night-time LReq,n is 59 dBA with an associated Severe impact. Mitigation of the main road would reduce the LReq,n in the order of 5 dB with the Severity of noise impact reduced to Severe within and west of the CBD and to Moderate east of the CBD Future noise impacts on the existing N2 if the Highway is developed: A predicted 58% of total traffic flow west of Knysna would travel to Knysna via the respective interchange and link road onto the Main Road to the CBD [BKS, 2008]. However, this information did not contain the predicted percentage heavy-duty vehicles during each hour. Knysna has no overnight stopping facilities for trucks. In discussion with the BKS traffic engineers, it was considered reasonable to assume that with the Toll Highway option all heavy-duty traffic after working hours would be through-traffic, not destined for Knysna. Therefore, for the Toll Highway option it was assumed there would be zero heavy-duty traffic on the Knysna Main Road during night-time and the total number of vehicles during each night-time hour was reduced accordingly. The LR,dn at the nearest residential boundaries would reduce to 62 dBA in 2008 where after it would increase to 63 dBA in 2013. The Severity of impact would remain unchanged as Moderate. The same impact would apply to the CBD. With no truck traffic during night-time the LReq,n on the Main Road within and west of Knysna would reduce to 49 dBA in 2008 where after it would increase to 50 dBA in 2013. The Severity of Impact would be Slight. East of the CBD the LR,dn at the nearest residential boundaries would reduce to 60 dBA in 2008 where after it would increase to 61 dBA in 2013. The Severity of impact would be Slight. During night-time the LReq,n would reduce to 47 dBA in 2008. This would increase to 48 dBA in 2013. The Severity of Impact would be Slight. The results of the calculations indicate that although there would be an insignificant reduction in noise level and associated impact during the day, the reduction during night-time would result in a highly significant reduction in impact from Very Severe to Slight. Mitigation would further reduce the Severity of noise impact to Negligible. Future noise impacts on the existing N2 if the Highway is not developed: The LR,dn in the CBD and at the residential boundaries along the Knysna Main Road west of the CBD would increase from 65 dBA in 2008 to 66 in 2013. The increase in terms of subjective human response to sound would be negligible. However the excess over the typical level would be 11 dB with an associated Severe impact. During night-time the LReq,n would increase from 61 dBA to 62 dBA in 2013 with an associated Very Severe noise impact. Rehabilitation of the road with a low-noise porous surface would reduce the Severity of impact to Severe. East of the CBD the LR,dn at the nearest residential boundaries would increase from 63 dBA in 2008 to 64 dBA in 2013. The difference would be insignificant. The Severity of impact would remain unchanged as Moderate. During night-time LReq,n would increase from 59 dBA in 2008 to 60 dBA in 2013 with the Severity of impact remaining as Severe. Mitigation would reduce the Severity of impact in 2013 to Moderate. Assessments of impacts are based on the night-time rating level of noise, LReq,n, that are highest in close proximity to the Main Road within and west of the Knysna CBD.



Significance statement for the existing N2 within the vicinity of Knysna Effect


Impact

Risk or Likelihood

Total Score


Existing Situation (2008) Without



Future Noise Impact if the Highway is developed Without

Mitigation permanent 4 Study Area 2 Slight 1 May occur 2 9 MODERATE

- With

Mitigation permanent 4 Study Area 2 Negligible 0 Unlikely 1 6 LOW -

Future Noise impact for the Do Nothing Option Without



9.6.2.3 Eastford and Salt River Interchanges With mitigation Proposed Route: Low-noise porous road surface, plus 2 m high noise barriers 1 m from link road, plus 5 m high noise barriers 1 m from the highway. (For impacts after only Low-noise porous road surface mitigation, refer to specialist report) This section encompasses the proposed construction of a new route on a plateau east of the Knysna River through conservation areas and small holdings that would lie north of the Proposed Route. Suburban residential land would lie primarily south of the Proposed Route but with some located north of the route. In this section there is no difference between the “Proposed” route and “Short” route alternatives as they follow the same alignment. The noise impact of the proposed highway and alternative Eastford and Salt River Interchanges with the associated roads linking with the Knysna Main Road are studied individually and compared. In addition to mitigation of noise provided by a low-noise road surface, this chapter studies the benefits and limitations of noise barriers as an additional noise mitigation option. It is important to note that in the noise modelling the barriers are located 1m from the edge of the road. The bottom of the barrier is then approximately at the same elevation as the road. Although in practice a greater distance might be required it would take excessively long to calculate the differences in elevation to be added or subtracted while ensuring the same height of the top of the barrier above the road surface.

Eastford Interchange: The noise emanating from the proposed highway, Interchange and link road would cause the LR,dn to exceed the measured residual daytime level of between 35 dBA and 38 dBA dBA over virtually all the land shown in Figure 9.14. This includes all land extending more than 1000 m North of the N2. The Severity of impact would range between Severe at the furthest range to Very Severe within 200 m of the road. Within approximately 300 m on either side of the highway and 160 m on either side of the link road the LR,dn would exceed the WHO recommended maximum level of 55 dBA for any residential land and the typical SANS level for urban residential land. The LR,dn would exceed the typical 50 dBA for a suburban residential district on all land shown in Figure 9.15 by between 5 and 15 dB up to the 65 dBA noise contour with an associated Severity of impact ranging between Slight and Very Severe, respectively. The NCR limit of 65 dBA would be exceeded on land extending approximately 60 m from the highway and 50 m from the link road. In terms of the NCR noise mitigation procedures would be required to reduce the noise levels within these distances to below 65 dBA.



Figure 9.14: Predicted LR,dn between Buffelsvermaak & Knysna River – with low-noise road surface.

Figure 9.15: Predicted LR,dn due to the highway through Eastford and Salt River with an interchange at Eastford – no noise mitigation.

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Mitigation includes, a 2m high noise barrier is located 1m east of the link road, 2m high noise barrier is located 1m from the southern off-ramp of the alternative Eastford Interchange and a 3m high noise barrier is located 1m from westbound carriageway of the proposed N2 Highway.

The 2m high noise barrier along the link road would result in a significant 10 dB reduction in LR,dn on land within 100 m of the wall. The raised elevation of the link road above land to the east would contribute to the added effectiveness of the noise barrier. However, with increased distance the noise reduction effect of the wall would decrease. An overall reduction of 5 dB on suburban residential land could be expected as shown in Figure 9.16b.

a. b. Figure 9.16: Eastford Interchange and link road a): Low-noise road surfaces b): Low-noise road surface plus noise barriers

An increased height of the noise barrier along the highway would be required due to a greater distance of the furthest, eastbound lanes from the barrier. The greater the distance between noise source and noise barrier, the less the noise reduction effectiveness of the barrier will be. A 3m noise barrier was chosen to illustrate that although a significant reduction in LR,dn could be expected close to the barrier, due to differences in elevation of the highway and adjacent land the reduction would be limited to 5 dB adjacent to the highway shown at the right of Figure 9.16. A more significant reduction in noise level adjacent to the highway would require the height of the barrier to be increased to at least 5m.

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Not withstanding the predicted reduction in LR,dn due to low-noise road surfaces and noise barriers, on the northern section of land flanked by the noise barriers the resulting level of 50 dBA would still exceed the existing the residual level of 36 dBA by 14 dB. The Severity of impact would be Severe. In this same area the excess of 5 dB over the typical level of 45 dBA for a rural residential district would result in a Slight Severity of impact. Further south, within the predicted 50 dBA noise contour, the LR,dn on land within this area would comply with the typical level for a suburban residential district. A further calculation was performed to illustrate the effect of raising the height of the noise barriers on both sides of the highway to 5 m, more specifically, a 2m high noise barrier is located 1m east of the link road, 2m high noise barrier is located 1m from the southern off-ramp of the Eastford Interchange. No barriers were included for the northern on and off ramps and 5m high noise barriers are located 1m from both outer carriageways of the highway.

Due to the higher elevation of the land north of the proposed N2 the increased height of the noise barrier to 5 m along the highway would result in a negligible reduction in LR,dn on virtually all of this land. There would thus be no reduction beyond that provided by a low noise road surface in the Severity of noise impact with regard to the measured existing daytime level of 36 dBA. The 5m high noise barrier along the southern edge of the highway would provide sufficient reduction in noise for the LR,dn to comply with the SANS typical level of 45 dBA for a rural residential district on all land beyond 150 m south of the highway in the Salt River area and much of the land towards the link road in the east with No impact in terms of the typical level. A similar reduction was anticipated for the alternative Salt River Interchange. Within 150 m south of the highway and extending to near the Interchange the LR,dn would comply with the typical level of 50 dBA for a suburban residential district with No noise impact in terms of the typical level excepting for relatively small land areas.

Saltriver Interchange: The noise emanating from the proposed highway, Interchange and link road would cause the LR,dn to exceed the measured existing daytime leves of 35 to 38 dBA over virtually all the land shown in Figure 9.17. This includes all land extending more than 1000 m North of the N2. The Severity of impact would range between Severe at the furthest range to Very Severe within the 50 dBA contour from the road. The 55 dBA LR,dn contour would extend approximately 600 m to the Northwest and 360 m Southeast of the highway in the vicinity of the alternative Salt River Interchange and 160 m on either side of the link road and would thus exceed the recommended maximum WHO level and the typical SANS level for urban residential land within these distance from the respective roads. The typical level of 50 dBA for suburban residential land would be exceeded on all suburban residential land shown in Figure 9.17 excepting for the Southeast residences overlooking the Knysna Main Road. The Severity of impact would range between Slight and Very Severe. The NCR limit of 65 dBA would be confined to land extending approximately 100 m from the highway in the vicinity of the Interchange and 50 m from the link road. In terms of the NCR noise mitigation procedures would be required to reduce the noise levels within these distances to below 65 dBA. Mitigation includes, a 2m high noise barrier is located 1m from the edge of each side of the link road, a 3m high noise barrier is located 1m from the on-ramps and off-ramps of the alternative Salt River Interchange and 3m high noise barrier is located 1m from westbound carriageway of the highway. The respective noise barriers, together with the low-noise road surface, would result in a significant reduction in LR,dn immediately adjacent to the link road and within 200 m of the interchange ramps. The noise reduction effect of the noise barriers would become minimal on flat land beyond approximately 200m from the road, with the influence of the road surface texture becoming predominant.



Figure 9.17: Predicted LR,dn due to the highway through Eastford and the Salt River with an interchange at Salt River – no noise mitigation.

It is evident that the varying topography would have a major influence on land exposed to road noise. The ridges, being parallel to the highway, would provide naturally high and effective noise barriers to land on the far side to noise emanating from the highway. However, the valley between the ridges would still be exposed to noise originating from the link road and the section of the highway in the west extending beyond the left of Figure 9.18. The valley would be in line with and thereby directly exposed to noise from one or both carriageways of the highway and Western on and off ramps as outlined in blue in the 3-D computer simulation in Figure 9.19 looking Westward down the valley flanked by the two ridges. Noise barriers flanking the highway would present little noise reduction. The level of noise would be determined primarily by the road surface texture. Land on the slopes of the ridges parallel to and overlooking the highway would be at a higher elevation and therefore more exposed to noise from the highway than land at the same elevation. Only the construction of very high noise barriers would provide significant noise reduction on the elevated land. Once again, the road surface texture would play a dominant role on the level of exposure to road noise.

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a. b. Figure 9.18: Salt River Interchange and link road a): Low-noise road surfaces b): Low-noise road surface plus noise barriers

Figure 9.19: 3-D simulation of view looking westward onto Salt River Interchange illustrating direct exposure to noise from the highway and ramps

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Comparing the Eastford and Saltriver Interchanges: The Eastford link road would be longer than the Salt River link road thereby exposing a longer band of affected land along its length. However it is for a large part contained within a valley that contains the distance from the link road of the respective noise contour lines. Much of the land in the vicinity of the alternative Salt River Interchange would be elevated above the highway thereby exposing a significantly larger area of land to higher noise levels compared to the alternative Eastford Interchange. In the absence of noise mitigation the Eastford Interchange would be the preferred alternative. After Noise Mitigation, the topography surrounding the alternative Salt River Interchange would expose a larger area of elevated land to noise emanating from this interchange compared to the alternative Eastford Interchange not withstanding the use of low-noise road surfaces. Due to the topography the use of noise barriers along the highway and link road of the Salt River Interchange would be less effective than that of the Eastford Interchange particularly in screening suburban residential land south of the highway. The results of the study indicate that the Eastford Interchange would be preferred with regard to a lower potential noise impact unless higher noise barriers were erected. This is considered in the following sub-chapter. Significance Statement for the highway between Eastford and Salt River



Risk or Likelihood

Total Score


Eastford Interchange – north of the highway Without

Mitigation permanent 4 Study Area 2 Very severe 8 Definite 4 18 VERY HIGH -

With Mitigation permanent 4 Study Area 2 Very Severe 8 Definite 4 18 VERY HIGH

- Eastford Interchange – south of the highway

Without Mitigation permanent 4 Study Area 2 Very severe 8 Definite 4 18 VERY HIGH

- With


Salt River Interchange- north of the highway Without


With Mitigation permanent 4 Study Area 2 Very severe 8 Definite 4 18 VERY HIGH

- Salt River Interchange – south of the highway


- With


9.6.2.4 All other Interchanges In order to facilitate the comparison of the different impacts arising out of the separate studies of the different disciplines in the overall EIA process this section includes a Significance Statement for the interchanges other than the interchanges at Eastford and at Salt River that have been considered in detail in section 9.6.2.3.



A visual impact study may consider the impact of the physical structure of an interchange in isolation from all roads connected to it. This has no meaning in a noise study. Without a highway and link roads connected to an interchange there would be no noise emanating from the interchange. The noise impact “due to” the interchange is the impact of the combined noise emanating from the entire length of the link road(s) connected to the interchange, from the highway, and from the interchange “footprint” comprising the on and off ramps and the bridge over the highway. The number and mean speed of the vehicles on the bridge and on each of the ramps within the “footprint” is significantly lower than on the highway and link road(s). Therefore the contribution of noise from the interchange compared to the total noise level approximately 20 m beyond the “footprint” is insignificant compared to that from the highway and from the link road(s), respectively. This is illustrated in the numerous Figures in section 9.6.2.3. In summary, the noise impact relating to an interchange is due to noise emanating from the roads connected to the interchange. Similarly, noise mitigation is understood to be that applied to the highway and link road(s) as presented in this report. Rheenendal Interchange A study of Figures 9.20 and 9.14 indicate that the levels of noise in the vicinity of the interchange are primarily due to the noise emanating from the highway. In the absence of the highway the noise contours due to noise from existing traffic on the Rheenendal Road would be similar to those shown furthest from the highway.

Figure 9.20: Predicted LR,dn between Buffelsvermaak & Knysna River – preferred route White Bridge Interchange The traffic flow on the link road is significantly less than that on the White Bridge. The impact is thus due to noise emanating from the White Bridge.

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Uniondale Interchange A study of Figure 9.21 indicates that the levels of noise in the vicinity of the interchange are primarily due to the noise emanating from the highway. In the absence of the highway the noise contours due to noise from existing traffic on the Uniondale Road would be similar to those shown furthest from the highway.

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KRUISFONTEIN STATE FOREST

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STATE FOREST

Figure 9.21: Predicted LR,dn due to the “Proposed” route between 1 km west of the Uniondale Interchange and Bracken Hill – no noise mitigation Springfield Interchange The interchange and link road would be in state forest far removed from residential or other noise sensitive land and would therefore not cause a noise impact. Significance Statement for Interchanges



Risk or Likelihood

Total Score


Rheenendal Interchange Without



White Bridge Interchange Without

Mitigation permanent 4 Study Area 2 Severe 4 Definite 4 14 HIGH -

With Mitigation permanent 4 Study Area 2 Moderate 2 Probable 3 11 MODERATE

- Uniondale Interchange


- With

Mitigation permanent 4 Study Area 2 Moderate 2 Probable 3 11 MODERATE -



With permanent 4 Study Area 2 Negligible 0 Unlikely 1 7 LOW -



Mitigation Brackenhill Interchange


- With

Mitigation permanent 4 Study Area 2 Moderate 2 Definite 4 12 HIGH -

9.6.2.5 Central highway (Saltriver –1km west of the Uniondale Interchange) common to

both Proposed Routes Mitigation: Low-noise porous road surface This section of the proposed N2 would skirt north of and close to several densely populated settlements extending 6 km east of the Salt River. In this study it was assumed that residential development would not spread onto Municipal and State forest land lying to the north of the Proposed Route. Compare to the Do Nothing option discussed in section 9.6.2.2. On all land within the calculation area south of the road edge the predicted LR,dn would exceed the 40 dBA measured on the Concordia Road north of one of the settlements. The typical level of 50 dBA for a suburban district would be exceeded within approximately 200 m of the road edge depending on the topography. The LR,dn would exceed 60 dBA within approximately 100 m from the road edge and exceed 65 dBA within approximately 50 m from the road edge. In terms of the typical LR,dn for a suburban district the severity of impact would thus range between Slight at 200 m distance to Moderate at 100 m distance from the road edge. Within 100 m from the road edge the severity of impact would range between Severe and Very Severe. Mitigation (low noise road surface): No calculations were conducted to predict the effect of a low-noise porous road surface for this section. From the results of modelling in section 9.6.2.4 it is anticipated that this would reduce each of the contour values shown in Figure 9.22 by approximately 5 dB. This would reduce the impact of noise on a significant area of settlement land as well as vacant land. The typical level of 50 dBA for a suburban district would be exceeded within approximately 150 m of the road edge depending on the topography. The LR,dn would exceed 60 dBA within approximately 50 m from the road edge. In terms of the typical LR,dn for a suburban district the Severity of impact would thus range between Slight at 150 m distance to Moderate at 50 m distance from the road edge.

Figure 9.22: Predicted LR,dn due to the highway between Salt River and 1 km west of the Uniondale Interchange – no noise mitigation.

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Mitigation 2 (low noise road surface + noise barriers): The road would comprise numerous cuts and fills along this entire section with varying amounts of noise screening as illustrated in Figure 9.22 by the varying distances of the 65 and 60 dBA noise contour lines from the road edge. The noise reduction effects of barriers have been illustrated in Chapter 7.3. The detailed and extensive modelling required to study the effects and optimisation of varying heights of noise barriers along this varying terrain is considered beyond the scope of an EIA. It is recommended that this be conducted at the detail design stage of the road. (Note, not reflected in Significance Statement table) Significance Statement for the highway between Salt River and Uniondale Interchange



Risk or Likelihood

Total Score


Salt River to Uniondale Interchange Without


With Mitigation permanent 4 Study Area 2 Moderate 2 Definite 4 12 HIGH -

9.6.2.6 Eastern Section (1 km west of the Uniondale Interchange till Brackenhill) With mitigation: Low-noise porous road surface plus 3 m high wall along the Proposed Route (Uniondale to Brackenhill) With mitigation: Low-noise porous road surface (Uniondale –Springfield) This section of the “Proposed” highway would skirt north of and close to settlements to the west and to the south of the proposed Uniondale Interchange. To the east of the proposed interchange the highway would pass through 4,5 km of unoccupied forestry land until the approach to the end of the Toll Highway at Bracken Hill where it would pass close to residential settlements before connecting with the existing N2. The Uniondale link road between the proposed interchange would for the most part pass through state forest land and connect with the existing N2 near Springfield. This is shown left of centre. Uniondale –Brackenhill: The southern extent of the noise contours was limited by the absence of digital elevation data south of the noise contour calculation area shown. In the west, on all land within approximately 500m of the road edge the predicted LR,dn would exceed the measured 40 dBA except for land south of the link road approach to the proposed interchange. The severity of impact of noise from the proposed highway would range between Slight at 500 m to Very Severe within 200 m of the road edge.



Figure 9.23: Predicted LR,dn due to the “Proposed” route between 1km west of the Uniondale Interchange and Bracken Hill – no noise mitigation

55

60 65

40

50

55 60

45 50 50 60

60

50

55

55

50 45

50

45

60

55

45

50

40

0 500 m

40

50 55

Bracken Hill

Existing N2 Springfield

Uniondale Road

Uniondale Interchange

KRUISFONTEIN STATE FOREST

CONCORDIA STATE FOREST

T



Most of the land containing residential settlements to the west and to the south of the proposed Uniondale Interchange would be exposed to an LR,dn of 50 dBA or less. In terms of the SANS typical level for suburban residential land there would be No noise impact in those areas. Small pockets of land at the extreme west and southwest of the interchange would be exposed to levels between 50 dBA and 55 dBA with an associated Slight noise impact. At Bracken Hill in the east the existing residences west of the existing N2 are in a valley that shields this rural residential land from noise emanating from the existing N2 but, the same valley would result in higher exposure to noise from the proposed highway than would be the case on level ground. LR,dn on residential land at Bracken Hill would range from 50 dBA at approximately 400 m to in excess of 65 dBA within 100 m of the proposed road. In terms of the typical level of 45 dBA for rural residential land the severity of impact would range between Slight at the 400 m to Very Severe within 100 m. Certain of the residences would be exposed to levels in excess of the NRC limit of 65 dBA with the legal requirement for noise mitigation procedures to be implemented to ensure levels on affected land were to be reduced to below 65 dBA. The LR,dn on land adjacent to the link road between the proposed Uniondale Interchange and the existing N2 at Springfield would exceed 45 dBA only within a few tens of metres of the road edge. It is anticipated that there would be No noise impact beyond approximately 50 m from the road edge. No calculations were conducted to predict the effect Mitigation (surface + barriers) for this section. However, from the results of modelling in section 9.6.2.4 it is anticipated that a reduction in LR,dn of between 10 dB and 15 dB would be achieved on the affected residential land at Bracken Hill by means of a combination of low-noise road surface and a noise barrier of at least 3 m height along the highway. The resultant severity of impact would then range between Slight and Moderate. The required height in relation to the distance of the barrier from the road edge would need to be determined at the detailed design stage of the highway. Uniondale –Springfield: The route would pass through state forest far removed from residential or other noise sensitive land and would therefore not cause a noise impact. The residential dwellings at Springfield would fall outside of the Short Route. However, the residential dwellings at Springfield would be located within 200 m of the alternative Toll Plaza. The impact of the Toll Plaza on these residences is considered in section 1.1.3. Significance Statement for the highway between west of the Uniondale Interchange and Bracken Hill – Proposed Route



Risk or Likelihood

Total Score


Uniondale Interchange to Bracken Hill Without





Significance Statement for the highway between west of the Uniondale Interchange and Springfield – Short Route



Risk or Likelihood

Total Score


Uniondale Interchange to Springfield Without


With Mitigation permanent 4 Study Area 2 Negligible 0 Unlikely 1 7 LOW -

9.6.3 Predicted Noise Impacts of Toll Plazas The prediction of noise emanating from toll plazas is not straightforward due to the combination of different types of noise associated with such infrastructure. These comprise the noise from deceleration and acceleration of vehicles through the toll plaza plus sporadic, impulsive types of noise emanating from individual vehicles when stopping at the tollbooths and subsequently accelerating away from the tollbooths. Experience has shown that these types of noise can be the dominant source of noise impact from a toll plaza. The standard procedures used to predict the noise from free-flowing traffic on freeways are inadequate to predict the total impact of noise from toll plazas. Neither the National Standards, nor the Noise Control Regulations, nor any other international standards contain procedures to predict or assess the impact of this type of noise. For this reason investigations were conducted at three typical mainline toll plazas throughout the country in order to characterize the different types of noise emanating from different sources and how they are perceived at distances from a toll plaza (Jongens Keet Associates, July 2002). From the results of the investigation proposed procedures were developed to predict the combined noise emanating from the different sources that is perceived at distances from a toll plaza and noise mitigation measures to be implemented to reduce the impact. The noise emanating from a toll plaza is associated with a mixture of several sound sources. The sources identified at one or more of three mainline toll plazas studied include: 1. General traffic operation sounds under stop-start (interrupted flow) conditions as vehicles pass

through the toll plaza. The noise fluctuates relatively little and slowly in level (loudness) and frequency content (tone) over a period of several seconds or minutes due to the collective noise of vehicles passing through the toll plaza.

2. These normal sounds are, however, interspersed with sporadic, and sometimes very loud abrupt emission of noise from single events occurring infrequently resulting in brief but significant changes in level and/or frequency of the ambient noise in close proximity to the tollbooths. Examples of the latter noise sources are, including:

∗ Vehicles with overly noisy engines and exhaust systems.

∗ Vehicles decelerating and accelerating excessively loudly. This includes respectively, Jacobs assisted brakes of heavy-duty vehicles that produce high levels of low-frequency throbbing noise; the “squeal” of brakes from some light- and heavy-duty vehicles as well as the sudden, loud, high frequency “hiss” accompanying compressed air release of brakes on many heavy-duty vehicles; and the loud revving of engines by some vehicles prior to accelerating away from the tollbooths.

∗ Rattling of badly maintained vehicles and badly loaded freight.

∗ Vehicles hooting.

∗ Radios in some vehicles being played very loudly.



∗ The noise produced by the tyres and suspension of a vehicle during interaction with the rumble strips on approaches to some of the plaza. The instantaneous, high impulse sound levels render this noise particularly noticeable at night when the ambient noise level is low.

∗ Intermittent sounding of a siren at the weighbridge indicating an overload of a heavy-duty vehicle.

Mitigation methods For detailes mitigation methods, please refer to section 9.6.1 In absence of any other noise mitigation measures, it has been calculated that the separation distance between a tollbooth and the nearest receiver location in each site should be no less than 950 m and 630 m, respectively. Where the separation distance is likely to be less than the distances given in the previous paragraph, noise mitigation measures may be required. The only practical alternative noise mitigation measure for noise produced in the vicinity of mainline tollbooths is a noise barrier extending on either side of the tollbooths. Typically, for a mainline toll plaza, the height required would be of the order of 5 m. However, the actual height would depend on the number of lanes and total width of the plaza. The typical length of the barrier required would be 100 m extending on either side of the tollbooths. A noise barrier, as described, will only be beneficial if the land to be protected from noise is located behind the barrier. Where receivers are directly in line with the approach lanes to the tollbooths a noise barrier placed parallel to the approach lanes will serve no purpose. A mainline toll plaza located on a slightly elevated section of the route, with the approach sections on a gradient, will facilitate deceleration of vehicles with an associated reduction in noise emission, particularly from heavy-duty vehicles. Similarly, after passing through the toll booths, the downward gradient will reduce the amount of power required and hence noise emitted during acceleration. This automatically occurs at ramp toll plazas. Impacts The Groenvlei alternative toll plaza is proposed to be located at the eastern end of Groenvlei as shown in Figure 9.23. It would be located more than 1000 m from any residence with the Lake Pleasant Hotel and holiday accomodation located 5000 m west of the toll plaza. the anticipated noise impact would be Negligible. A potential exception would be the noise emitted during braking by heavy-duty vehicles fitted with Jacobs assisted brakes approaching the toll plaza. With reference to the beneficial effect of elevation, it could be debated to locate the plaza 2500 m further eastward where there is an elevated and level section of road. However, this would bring the toll plaza to within 450 m of farm residences located to the east. This location is therefore not supported. The Buffelsvermark (Proposed Route) toll plaza and approach sections of the proposed highway would be in a valley whose ridges would provide adequate noise screening for the nearest farm residences located 700 m south of the plaza location. It is anticipated that there would be a Negligible noise impact of the toll plaza on these residences. Due to the separation distance between the Groenvlei tollbooth and the nearest receiver location The impact of the Eastford toll plaza would excacerbate an already Very Severe impact on several residences on the hills that would overlook the highway and toll plaza. A noise barrier of at least 5 m high along each side of the toll plaza, as well as along the highway would be required to reduce the LR,dn to below 50 dBA on adjacent land. The predicted impact on the rural residential district would then range between Moderate and Slight. The actual height would need to be determined at the detail design of the toll plaza. However, noise emanating from heavy-duty trucks fitted with Jacob assisted braking systems would still be distinctly audible and probably intrusive.



Figure 9.23: Proposed location of the alternative Groenvlei toll plaza. The Brackenhill Toll Plaza would be within 100 m of several farm/small holding residences and have a Very Severe noise impact on all these residences. Mitigations methods are identical to those discussed for the Eastford toll plaza discussed above. The Springfield Toll plaza would be within 100 m of several residences and have a Very Severe noise impact on all these residences. The mitigation methods are identical to those discussed for the Eastford Toll Plaza above. A noise barrier of at least 5 m high along each side of the toll plaza, as well as along the highway would be required to reduce the LR,dn to below 50 dBA on adjacent land. The predicted impact on the rural residential district would then range between Moderate and Slight. The actual height would need to be determined at the detail design of the toll plaza. With reference to Chapter 8.2.2 noise emanating from heavy-duty trucks fitted with Jacob assisted braking systems would still be distinctly audible and probably intrusive Significance Statement for Toll Plazas



Risk or Likelihood

Total Score


Groenvlei Toll Plaza Without



Buffelsvermaak Toll Plaza Without



Eastford Toll Plaza Without permanent 4 Study Area 2 Very severe 8 Definite 4 18 VERY HIGH





Risk or Likelihood

Total Score


Mitigation - With

Mitigation permanent 4 Study Area 2 Moderate 2 Definite 4 12 HIGH -







9.6.4 Noise Impacts during Construction Phase Various forms of construction activities will take place along different parts of the proposed Toll Highway varying from extensive earth movement of land, possibly including blasting, to final surfacing of the roads. All types of construction activities, whether of buildings or of roads, are accompanied by levels of noise that exceed typical noise levels found in various districts. Such noise is generally of limited duration and provided such activities do not produce excessive noise levels and do not occur during normal rest periods of a community the noise is usually tolerated. The topography of the land through which the proposed Toll Highway will pass in each of the sections considered in Chapter 7 is highly variable and will have an equally variable influence on the propagation of noise from noise source(s) to the numerous receiver locations whence variation in impact of the noise. In addition the noise emission from road construction machinery and vehicles and their duration of operation at any time during a day is also highly variable. The noise emission of similar machines or vehicles can vary significantly depending on the manufacturer. Thus, to attempt a specific and detailed impact study for each section of the road at the EIA phase would have little meaning nor confidence. The detailed noise emission data could only be determined after the detail design stage of the road when the specific type and number of construction machines and vehicles become known. This Chapter thus considers road construction noise and mitigation measures in general terms. The level of noise emitted by machinery is related to the mechanical power required by the machine to perform the required function. For example, greater power is required by a bulldozer to move earth than a paver to lay a new bituminous road surface. Thus, in principle, higher noise emissions may be expected from a bulldozer than machinery used for road surfacing. However, noise emission is strongly dependent on the manufacturer and on the “noise reduction packages” incorporated by the manufacturer of the machinery. With the increasing enforcement of noise control legislation throughout the world, manufacturers have been “encouraged” and are capable of supplying new heavy-duty machinery/vehicles with very low noise emission levels. Blasting activities are very sophisticated and are strictly legislated. Contrary, perhaps to the uninitiated, blasting of rock can take place with little emission of airborne sound and of ground vibration. During blasting operations at a quarry, had the author not visually observed blasting taking place less than 200 m away, he would not have been aware of the fact.



The noise emitted by earth moving machinery and heavy duty vehicles can vary considerably during normal operating conditions. The results are rarely repeatable making it difficult to compare the noise emissions of different vehicles. For this reason the noise emission is measured under controlled conditions such that the same values are obtained when repeated under the same operating condition. The author has measured the noise emission of numerous types of heavy-duty vehicles and of earth moving machinery of different manufacturers under controlled conditions as well as under normal operating conditions. Results obtained under controlled conditions were within 0,5 dB of those provided by the manufacturer, where the information was supplied. However, such results excluded additional sounds as are produced by rocks falling into trucks during loading, squealing of the rubble as it slides out of the truck during dumping, reverse hooter and the effect of the engine operating under differing loads. Sound measurements were therefore also recorded of numerous front end loaders, trucks and bulldozers during normal operating conditions. The emission of noise by a source is normally recorded in octave frequency band sound power levels obtained from measured octave frequency band sound pressure levels at a known distance from the noise source thereby permitting direct comparison of sound energy sources and enabling the calculation of the sound pressure level at a known distance in accordance with SANS 1035, The calculation of sound propagation by the Concawe method. Table 9.14 records the sound power levels, LW (dB), emitted by typical heavy-duty machinery that might be used during new road construction and the calculated separation distance over unobstructed land required for the outdoor LAeq,T (dBA), during continuous operation, to decrease to 65, 55 and 45 dBA, respectively. These represent the LAeq,T of two of the “noisier” activities recorded, including reverse hooters and noise associated with dumping of rubble, and can thus be considered to be worst-case scenarios. Table 9.14: LW emission of heavy-duty machinery and separation distances required for different LAeq,T values

Separation distance, m, for, Machinery & operating conditions LW, dB 65 dBA 55 dBA 45 dBA CAT D11 bulldozer moving earth, reversing and repeating – several cycles 115 135 378 944

CAT5130B front-end loader loading CAT777D truck after approaching and subsequently leaving loading area – several cycles

112 79 229 602

Assessment − The 5th column provides an indication of the separation distance on rural land at which noise

from the particular operation would barely be audible.

− The 4th column provides an indication of the separation distance at which the noise would be distinctly noticeable on rural land with an associated medium severity of noise impact whereas in a suburban district it would be noticeable with an associated low severity of noise impact.

− The 3rd column provides an indication of the separation distance beyond which the LAeq,T would comply with the NCR limit but with an associated impact of very high and high on rural and suburban land, respectively, and decreasing with increasing distance.



The significance of the impacts would depend upon the total duration of the construction activities in the vicinity of receiver locations. The impact may be reduced by not only utilising construction processes and machinery with low noise emission values, but also by increasing the number of vehicles/machinery needed to shorten the total construction duration in a particular area as much as possible. The latter is based on the scientific fact that a doubling of sound power emission results in only a 3dB increase in sound level at a receiver location; an almost imperceptible difference. Thus, utilising two similar trucks simultaneously will cause a 3 dB increase over that of one truck. Utilising four trucks simultaneously will result in a further 3 dB (total 6 dB). Utilising eight trucks simultaneously will add a further 3 dB (total 9 dB). A 6 dB difference in sound level is perceived as significant while 9 dB is perceived as an almost doubling of “loudness”. In practice, however, vehicles/machinery on a construction site do not all generate noise simultaneously. For example, a truck idles (generating little noise) while a front-end loader emits noise while loading the truck. As a full truck generates noise as it moves away, the front-end loader idles (generating little noise) while waiting for the next truck. The construction activities may result in ground vibration associated with compaction of the earth being perceived at nearby residences or other noise sensitive land. This may be accompanied by noise of rattling of fixtures to buildings. It is difficult to quantify the noise impact associated with this activity. The intensity and significance of this impact may similarly be reduced by shortening the total duration of the compaction process. Recommendations The following recommendations are made where road construction/rehabilitation takes place within approximately 1 km of residential and other noise sensitive land:

− Construction processes and machinery/vehicles with the lowest noise emission values available are utilised.

− A well planned and co-ordinated “fast track” procedure is implemented to complete the total construction process in any area in the shortest possible time.

− Construction only takes place during normal daytime working hours. No construction activities are to be permitted during weekday evenings and night-time, on Saturdays after midday and the entire day on Sundays.

In addition to the above it is recommended that details of all construction machinery and vehicles be determined prior to construction in order to identify potentially noisy machinery and to seek possible alternatives. Details would include the manufacturer, type and noise emission data of each machinery/vehicle and how many will be used at any time along each section of the route. Manufacturs of modern vehicles and machinery provided for the international market are obliged to provide noise emission data. Where this information is not available noise measurements may need to be conducted on such machinery or vehicles. 9.6.5 Conclusions The results of the study indicated the following:

• The existing levels of noise on most of the land located away from the existing N2 are low. They are lower than the SANS 10103 typical levels for “rural districts” and “suburban districts with little road traffic”. This, together with the unique estuary and forest land of the area is what attracts holiday makers and potential investors of land to the region.



• The Toll Highway would very significantly increase the levels of noise on large areas of land including farmland, small holdings, nature reserves, residential land and tourist accommodation. The Severity of impact on occupied and unoccupied land would range between Severe and Very Severe. This will irrevocably destroy a portion of the uniqueness of Knysna

• The alternative “Short” routes at the western and eastern ends of the highway would minimise the expansion of the noise footprint and, in particular, avoid the severe impact on farmland, small holdings, nature reserves, residential land and tourist accommodation located along the western section of the highway where it crosses the Knysna River.

• The use of low-noise porous road surfaces would reduce the severity and extent of noise impact.

• However, in areas close to settlements additional mitigation measures would be required. In these areas the combined use of low-noise porous road surfaces and noise barriers erected close to the highway and link roads would be required to reduce the noise levels and associated Severity of impacts to Moderate or lower.

• Due to the undulating topography even very high noise barriers would be inadequate to reduce the noise levels and associated Severity of impacts on elevated land overlooking the highway such as in the Eastford and Salt River areas.

• Construction of the Toll Highway would not significantly reduce the levels of noise and existing severity of the noise impact along the existing N2 during daytime or based on a 24-hour day/night time period. An exception would be for the section between Buffelsvermaak and the western bank of the Knysna River where there would be a very substantial benefit.

• During night-time a very high percentage of heavy-duty traffic passes residences, tourist accommodation and businesses located in close proximity to the Main Road through Knysna. The existing noise impact including that in the CBD during night-time is Very Severe. Upon construction of the highway it is assumed that all night-time heavy-duty traffic would be removed from the Knysna Main Road. This would result in a very substantial benefit to occupants of affected land with the Severity of impact reducing to Slight. Rehabilitation of the Main Road with a low-noise porous surface would further reduce the Severity of noise impact to Negligible.

• However, the reduction of noise impact on Knysna businesses and on residential dwellings in the immediate vicinity of Knysna would be at the cost of a significant noise impact during daytime and night-time on very much larger areas of land and on many more residential dwellings. The detrimental effects would thereby overshadow the benefits.

• Other than at Groenvlei and Buffelsvermaak the Toll Plazas at the proposed locations would cause a Very Severe impact on neighbouring land. High and long noise barriers would be required to reduce the impact to between Moderate and Slight.

Table 9.15: Summary of significance of Noise Impacts (Operational Phase) Issue/Impact Significance Without With Mitigation

Western Section(Groenvlei -Knysna river) Proposed route Very High - High - Short route High - Moderate - No Go (Western section) Moderate - Moderate -

Central ( Westem half-Salt River -Uniondale) Both routes-eastern half Very High - High -

Existing N2 (Current and Future) Existing situation (2008) Very High - High -



Issue/Impact Significance Without With Mitigation

Existing N2 with Highway Moderate - Low - Existing N2 without Highway Very high - High -

Eastern Section Uniondale -Brackenhill (proposed) Very High - High - Uniondale -Springfield (short) Low - Low -

Interchanges Eastford -North of N2 Very HIGH - Very High - Eastford -South of N2 Very HIGH - Low - Salt River-North N2 Very HIGH - Very High Salt River-South N2 Very HIGH - Low - Rheenendal Interchange Very High - High - White Bridge Interchange High - Moderate - Uniondale Interchange Very High - Moderate - Springfield Interchange Low - Low - Brackenhill Interchange Very High - High -

Toll Plazas Groenvlei Low - Low - Buffelsvermaak Low - Low - Eastford Very high - High - Springfield Very high - High - Brackenhill Very high - High - Arising out of the study the following recommendations are made:

• The effectiveness of noise barriers is strongly dependent on the distance of the barriers from the road edge. In this study the noise barriers have been assumed to be very close to the road edges. With increased separation distance the height would need to be increased. It is thus recommended that more detailed noise studies be conducted to optimise the height and location of noise barriers at the detail design stage of the highway. This should include noise barriers along toll plazas.

• The study brief was restricted to a comparison of noise impact of the two highway alternatives with that of the existing N2. The author is aware that the Knysna Municipality has plans to reroute traffic along the Waterfront area, and that the impact of this on traffic flow has been assessed in the Traffic study for the Highway EIA. If this plan is to be implemented, it is recommended that a noise assessment be undertaken.

9.7 Economic Impacts The following economic impacts have been identified in the previous sections of this report:

1. Increased local (Knysna Municipality) and provincial GDP. 2. Increased employment. 3. Reduced costs of transport. 4. Increased tourism. 5. Positive and negative effects on property prices. 6. Negative effects on Sedgefield/Karatara residents. 7. Negative effects on Brenton-on-Sea/Belvidere/Buffels Bay residents. 8. Costs of tolls to Knysna residents. 9. Negative effects for the forestry sector. 10.Impacts of the alternative main interchanges. 11.Impacts of the alternative bridge options over the Knysna River. 12.Costs of resettlement.



13.Increased availability of land for housing 14.Costs of proclaiming and expropriating additional land.

These impacts are described and rated in the remainder of this section for the Proposed Route, Short Route and the Do Nothing option, using the CES assessment and scoring format. As explained in earlier sections of this report, a toll highway would have no impact on retail prices and a neutral impact on lagoon traders. Thus, these impacts are not dealt with below. 9.7.1 Impact 1: Increased GDP Cause and Comment The construction of a toll highway would, through multiplier effects, lead to an increase in provincial, district and municipal GDP. This increase in GDP would arise from the expenditure on construction and maintenance of the highway and the multipliers associated with this, but also as a result of the improved traffic growth and the indirect impact this would have on economic growth in the Knysna area. Conversely, the Do Nothing option would lead to a stagnation and perhaps even a decline in local economic growth as the town traffic became gridlocked before 2013. As would be expected, the larger scale of the Proposed Route results in a greater impact on GDP than is the case with the Short Route. Significance Statement



Risk or Likelihood

Total Score



Construction Short term 1 Regional 3 Mod Beneficial 2 Definite 4 10 MODERATE +

Operation Permanent 4 Regional 3 Mod Beneficial 2 Definite 4 13 HIGH +

Proposed Route- After Mitigation Construction NA NA NA NA NA NA

Operation NA NA NA NA NA NA Short Route- Before Mitigation

Construction Short term 1 Regional 3 Mod Beneficial 2 Definite 4 10 MODERATE +

Operation Medium term 2 Regional 3 Mod

Beneficial 2 Definite 4 11 MODERATE +

Short Route- After Mitigation Construction NA NA NA NA NA NA

Operation NA NA NA NA NA NA No Toll Highway- Before Mitigation

Construction NA NA NA NA NA NA

Operation Permanent 4 Regional 3 Very

Severe Negative

8 Probable 3 18 VERY HIGH -

No Toll Highway- After Mitigation Construction NA NA NA NA NA NA

Operation NA NA NA NA NA NA Mitigation and Management The Do Nothing option would inevitably have to give way to a Traffic Management Plan, but even this would not be a viable solution after 2013. The construction of a highway is inevitable. However, since the Do Nothing option is defined as a completely Do Nothing (i.e., do-nothing) option, no mitigation is identified.



9.7.2 Impact 2: Increased Employment Cause and Comment The construction phase of the highway would create approximately 210 additional jobs, most of these unskilled or semi-skilled. The contract between SANRAL and the road construction company will specify that preference should be given to local residents in order to maximise the local impact. In the operational phase, the number of direct jobs created would be minimal, but the employment multiplier in SAM indicates that jobs would be created indirectly in the local economy through the higher economic growth rate that would be made possible. The Do Nothing option could lead to a loss of jobs in the long term. Mitigation and Management No mitigation measures are identified. Significance Statement



Risk or Likelihood

Total Score



Construction Short term 1 Regional 3 Slight Beneficial 1 Definite 4 9 MODERATE

+

Operation Permanent 4 Regional 3 Slight Beneficial 1 Probable 3 11 MODERATE

+ Proposed Route- After Mitigation

Construction NA NA NA NA NA NA Operation NA NA NA NA NA NA


Construction Short term 1 Regional 3 Slight Beneficial 1 Definite 4 9 MODERATE

+

Operation Medium term 2 Regional 3 Slight

Beneficial 1 Probable 3 9 MODERATE +




Operation Long term 3 Regional 3 Severe Negative 4 Probable 3 13 HIGH -


Operation NA NA NA NA NA NA 9.7.3 Impact 3: Transport Costs Cause and Comment The Do Nothing option will result in high transport costs for road hauliers, industry, retail establishments and private motorists arising from traffic congestion (increased vehicle operating costs, time costs, accident costs). Conversely, these costs will be reduced by the construction of a highway. This reduction in transport costs will far exceed the toll fees that will be paid. Mitigation and Management No mitigation measures are identified.




Phase Temporal Scale Spatial Scale Severity of

Impact

Risk or Likelihood

Total Score


Proposed Route- Before Mitigation Construction NA NA NA NA NA NA

Operation Long term 3 National 3 Beneficial 4 Probable 3 13 HIGH + Proposed Route- After Mitigation


Short Route- Before Mitigation Construction NA NA NA NA NA NA

Operation Medium term 2 National 3 Beneficial 4 Probable 3 12 HIGH +




Operation Permanent 4 National 3 Severe Negative 4 Definite 4 15 HIGH +


Operation NA NA NA NA NA NA 9.7.4 Impact 4: Increased Business Opportunity Cause and Comment The Do Nothing option will result in traffic gridlock before 2013 with the resultant loss of Knysna’s main attractiveness for tourism and consequently other business. The construction of a highway will alleviate the traffic problems and facilitate rather than constrain growth in the tourism industry as well as other business in Knysna. It might also induce a fair proportion of passing motorists to visit the town and stop for a meal or refreshment. At present, an insignificant volume of business is done with passing motorists. Mitigation and Management No mitigation measures are identified. Significance Statement



Risk or Likelihood

Total Score



Operation Long term 3 Regional 3 Beneficial 4 Probable 3 13 HIGH + Proposed Route- After Mitigation



Operation Medium term 2 Regional 3 Beneficial 4 Probable 3 12 HIGH +




Operation Permanent 4 Regional 3 Severe Negative 4 Probable 3 14 HIGH -

No Toll Highway- After Mitigation





Risk or Likelihood

Total Score



9.7.5 Impact 5: Positive and Negative Effects on Property Prices Cause and Comment The Do Nothing option would probably lead to a reduction or stagnation in property prices as tourism falls and traffic congestion remains severe. The highway could have a negative effect during construction on property prices in the area traversed, but overall it might in fact enhance prices in Knysna as the town regains or maintains its attractiveness as a location for holidaymakers, business and retirement. This impact is relevant to the central section of the highway which is common to both the ‘Proposed’ and ‘Short’ routes. Mitigation and Management No mitigation measures are identified. Significance Statement



Risk or Likelihood

Total Score



Construction Short term 1 Study area 2 Slight

Negative 1 Unlikely 1 5 LOW -

Operation Long term 3 Study area 2 Slight

Beneficial 1 May occur 2 8 MODERATE +



Construction Short term 1 Study area 2 Slight

Negative 1 Unlikely 1 5 LOW -


Beneficial 1 May occur 2 8 MODERATE +




Operation Permanent 4 Study area 2 Slight

Negative 1 May occur 2 9 MODERATE -


Operation NA NA NA NA NA NA



9.7.6 Impact 6: Negative Effects of tolls on Sedgefield/Karatara Residents Cause and Comment Residents of Sedgefield/Karatara (including taxi owners and users) would have to pay a toll for intra-municipal travel. The costs of paying the toll might be offset by time savings and reduced vehicle operating costs, but the overall effect is nevertheless likely to be negative. Mitigation and Management The mitigation measure would be to exclude Sedgefield and Karatara residents from payment of the toll fee. A suitable technology would need to be instituted to prevent scams. Significance Statement



Risk or Likelihood

Total Score



Operation Permanent 4 Study area 2 Moderate

negative 2 Definite 4 12 HIGH -



positive 2 Definite 4 12 HIGH +



negative 2 Definite 4 12 HIGH -



positive 2 Definite 4 12 HIGH +

9.7.7 Impact 7: Negative Effects of tolls on Residents of Brenton-on-Sea, Belvidere and

Buffels Bay Cause and Comment Under the Short Route the residents of these three residential areas would have to travel several kilometres further than they do at present to get to and from central Knysna because of the closure of the present N2 at White Bridge and the construction of a longer road across Red Bridge. This is only the case if the toll plaza is located at Eastford, and only for their journey out of town. If the toll plaza is located at Groenvlei, the residents will not be affected by their trip into Knysna. This impact is only relevant to the western section of the highway. Mitigation and Management This would involve the continued unrestricted access from White Bridge to Lagoon Road, and the closure of the existing N2 at a point to the west of the Rheenendal road rather than in Lagoon Road. Significance Statement



Risk or Likelihood

Total Score


Toll Plaza Located at Eastford – Before Mitigation Construction NA NA NA NA NA NA

Operation Long term 3 Localised 1 Moderate

negative 2 Definite 4 10 MODERATE -

Toll Plaza Located at Groenvlei – Before Mitigation Construction NA NA NA NA NA NA





Risk or Likelihood

Total Score


Operation Long term 3 Localised 1 Moderate

positive 2 Definite 4 10 MODERATE +

9.7.8 Impact 8: Cost of tolls to Knysna Residents Cause and Comment All Knysna residents would have to pay tolls on the outbound trip from Knysna to George or Plettenberg Bay and beyond. This would affect commuters and “semigrants” the most, and may encourage them to relocate outside of Knysna. However, residents would derive benefits from both reduced congestion and lowered road user costs. It is questionable whether these benefits would sufficiently offset the full toll for individual users. Mitigation and Management The mitigation measure would be to provide discounted toll fares to these frequent users. By providing a discount, there is a far higher probability that the overall cost for road users will be less with either of the highway options than with the current situation. Significance Statement



Risk or Likelihood

Total Score



Operation Long term 3 Study area 2 Moderate

negative 2 Probable 3 10 MODERATE -



positive 1 Probable 3 9 MODERATE +


Operation Long term 3 Study area 2 Moderate

negative 2 Probable 3 10 MODERATE -



positive 1 Probable 3 9 MODERATE +

9.7.9 Impact 9: Negative Effects for the Forestry Sector Cause and Comment MTO Forestry (Pty) (Ltd) could lose some of its growing area when the highway is built, it could find it necessary to construct additional firebreaks, and it could also find that it has to pay a toll fee in order to reach some of its forests (the last-mentioned point being particularly important in the event of a fire). This impact is only relevant to the eastern section of the highway from the Uniondale interchange to the Brackenhill interchange. Mitigation and Management The mitigation measures would be to compensate MTO for the cost of additional firebreaks, and to ensure that there are sufficient underpasses for MTO’s vehicles to continue being able to drive unimpeded in its forests without the cost of toll fees.





Impact

Risk or Likelihood

Total Score



Construction Short term 1 Regional 3 Mod negative 2 May


Operation Permanent 4 Regional 3 Mod negative 2 May



Construction Short term 1 Regional 3 Slight negative 1 May

occur 2 7 LOW -

Operation Permanent 4 Regional 3 Slight positive 1 May

occur 2 10 MODERATE +



occur 2 7 LOW -

Operation Medium term 3 Regional 3 Slight

negative 1 May occur 2 9 MODERATE -



occur 2 7 LOW -

Operation Permanent 4 Regional 3 Slight positive 2 May

occur 2 11 MODERATE +

No Toll Highway- Before Mitigation Construction NA NA NA NA NA NA

Operation NA NA NA NA NA NA No Toll Highway- After Mitigation


9.7.10 Impact 10: Impacts of the Alternative Main Interchanges Cause and Comment An interchange needs to be constructed to connect the town to the toll highway. The alternative interchanges and link roads are at Eastford and Salt River in the central section of the highway which is common to both the Proposed and Short Routes. Inevitably, there will be some disruption along these routes during the construction phase, but a comparison shows that the Eastford route would be preferred in terms of economic impact on the residential area traversed. There are two reasons for this. First, according to the Noise Impact Assessment, it is anticipated that the Salt River Route would generate a greater amount of noise during operation. Secondly, the Salt River Route will cost an extra R60.9 million to build. Mitigation and Management No mitigation measures are identified. Significance Statement



Risk or Likelihood

Total Score


Salt River Interchange- Before Mitigation

Construction Short term 1 Localised 1 Moderate negative 2 Probable 3 7 LOW -

Operation Permanent 4 Localised 1 Moderate negative 2 Probable 3 10 MODERATE -

Eastford Interchange- Before Mitigation

Construction Short term 1 Localised 1 Mod negative 2 Probable 3 7 LOW -

Operation Permanent 4 Localised 1 Slight negative 1 May




9.7.11 Impact 11: Economic costs of the Alternative Bridge Options over the Knysna River Cause and Comment Bridges are probably the most expensive component of the construction of new roads. There are three options for the bridge over the Knysna River for the Proposed Route, namely, the short bridge, long bridge and cable stayed bridge. The two latter options will cost an additional R132 million and R352 million respectively. The additional cost of widening the White Bridge and constructing the viaduct over the floodplain amounts to R211.6 million and offsets some of the savings from shortening the road. This accounts for the high costs of the shorter route relative to the longer Proposed Route. These additional costs will clearly increase the required toll fees and offset any savings on toll fees that could have been associated with the Short Route. However, the overall increase in costs for the Highway associated with the bridges are small, so the relative impact on total costs are considered slight. Bridge Options Cost Additional Cost Proposed Bridge A R64 million Proposed Bridge B R188 million R132 million Proposed Bridge C R284 million R352 million White Bridge widening + viaduct R211.6 million R147.6 million This impact is only relevant to the western section of the highway from Groenvlei to Eastford. Mitigation and Management No mitigation measures are identified. Significance Statement



Risk or Likelihood

Total Score


Proposed Route Bridge A - Short Bridge Option – Before Mitigation

Construction Short Term 1 Localised 1 Neutral 0 May

occur 2 0 NEUTRAL

Operation NA NA NA NA NA NA Proposed Route Bridge B - Long Bridge Option – Before Mitigation

Construction Short Term 1 Localised 1 Slight

negative 1 May occur 2 5 LOW -

Operation NA NA NA NA NA NA Proposed Route Bridge C - Cable Stay Bridge Option – Before Mitigation

Construction Short Term 1 Localised 1 Moderate


Operation NA NA NA NA NA NA Short Route – Widening of White Bridge and Viaduct



Operation NA NA NA NA NA NA 9.7.12 Impact 12: Economic Costs of the Alternative Bridge Options over the Salt River Cause and Comment There are three options for the bridge over the Salt River for the Highway (‘Proposed’ and ‘Short’ routes), namely, the twin box girder on rectangular piers, the cable stayed box girder with single A-frame tower or the twin box girder on rectangular tiers with central arch. The two latter options will cost an additional R75 million and R35 million respectively. This will clearly increase the required toll fees, but only marginally. This impact is relevant to the central section of the highway.



Mitigation and Management No mitigation measures are identified. Significance Statement



Risk or Likelihood

Total Score


Twin box girder on rectangular piers – Before Mitigation

Construction Short Term 1 Localised 1 Neutral 0 May

occur 2 0 NEUTRAL

Operation NA NA NA NA NA NA Cable stayed box girder with single A-frame tower – Before Mitigation



Operation NA NA NA NA NA NA Twin box girder on rectangular tiers with central arch – Before Mitigation



Operation NA NA NA NA NA NA 9.7.13 Impact 15: Resettlement Costs Cause and Comment The costs of resettling those who have encroached into the road reserve in the Concordia area will be the responsibility of the local municipality and the Department of Housing, using housing and land grants. This would be part of an ongoing housing programme so therefore is not an extra expense. This impact will occur along the central section of the highway and is the same for both the route alternatives. In the case of the ‘Do Nothing’ option, there would be no change in the housing costs for the government authorities and no improvement in living conditions for the households illegally living on the road reserve. Mitigation and Management There are no economic mitigation measures. Significance Statement



Risk or Likelihood

Total Score



Construction Short term 1 Localised 1 Slight

negative 1 Definite 4 7 LOW -



negative 1 Definite 4 7 LOW -

Operation NA NA NA NA NA NA Do Nothing Alternative




9.7.14 Impact 16: Increased Availability of Land for Housing Cause and Comment The construction of the highway would necessitate a new road alignment at the Uniondale road/Highway intersection, and facilitate the development by the municipality of land leased by MTO for forestry. This land would be used for housing, industry and a cemetery. Under the Do Nothing option, land for housing will still have to be acquired. Such land is at present in very short supply. Again, it needs to be stressed that the Do Nothing option would not make the road reserve land available for housing developments. The impact is relevant to the common central section of the highway and therefore applies to both the route alternatives. Significance Statement



Risk or Likelihood

Total Score



Operation Medium term 2 Study

area 2 Beneficial 4 Probable 3 11 MODERATE +


Operation Medium term 2 Study

area 2 Beneficial 4 Probable 3 11 MODERATE +

Do Nothing Alternative Construction NA NA NA NA NA NA

Operation NA NA NA NA NA NA Mitigation and Management None. 9.7.15 Impact 17: Cost of Proclaiming Additional Land Cause and Comment As a result of changes in the alignment of the two highway options, additional land will need to be proclaimed, amounting to between 38.3-39.0 hectares and 50.6-51.3 hectares for the Short and Proposed Routes respectively. The table below indicates that the 60-70% of this land needs to be acquired in the eastern section of the highway which is dominated by forestry land uses, and another 20-33% would need to be acquired in the western section which is dominated by farming land uses. The 10% of land needed in the central section will affect residential properties and will be slightly higher if the Salt river interchange is developed as opposed to the Eastford interchange. Highway Sections Proposed Route Short Route Western Section 17.1 ha 7.9 ha Central Section 3.3-4 ha 3.3-4 ha Eastern Section 30.2 ha 27.1 ha Mitigation and Management Compensation can be paid to the land owners. This will need to be at a fair market value of the land. Also, it must be stressed that if the claimed portion of land results in the rest of the land being unusable, compensation should be made for the full value of the full property.





Impact

Risk or Likelihood

Total Score




negative 1 Probable 3 6 LOW -

Operation NA NA NA NA NA NA Proposed Route- After Mitigation

Construction Short term 1 Localised 1 Neutral 0 Probable 3 0 NEUTRAL



negative 1 Probable 3 6 LOW -

Operation NA NA NA NA NA NA Short Route- After Mitigation

Construction Short term 1 Localised 1 Neutral 0 Probable 3 0 NEUTRAL




Operation NA NA NA NA NA NA 9.7.16 Conclusions from the Economic Assessment 9.8 Conclusion This study involved both a qualitative and a quantitative analysis. The qualitative analysis was based significantly on interviews conducted during fieldwork. During these discussions, a number of issues were raised. Although there was a general consensus that Knysna needed a highway, there was strong opposition to the tolling of intra-municipal traffic. The mitigation measures proposed include a significant reduction in toll fees payable by residents, and an analysis was performed on the financial effects of excluding them from paying toll fees. It was found that the toll fees increased by 13.4% following an 80% reduction for the LUD and a 100% reduction in the special LUD for Class I vehicles. This would cover all local, frequent users. However, it is pointed out that this is just one example and the values could be adjusted. A perception that a highway could have a negative effect on some property values was investigated with local estate agents and a property valuer. The view was that the prices of properties in the vicinity of the road reserve were discounted at the time of purchase. In fact, it was suggested that a number of properties may even increase in value with better access and reduced congestion in the town. It was suggested that, following the tolling of the N2, the price of goods would rise in Knysna. This is a highly flawed perception. Not only would transporters gain from greatly reduced operating costs (including VOCs, time and accident costs) despite a toll fee, but the major retail outlets confirmed that the toll fee would be insignificant in terms of the value of goods carried and that in any case the prices of goods are set at a national level. Some argued that Knysna would lose business as road users would now bypass Knysna. As Knysna is a destination in itself, this is unlikely. Again, interviews confirmed that passing traffic’s contribution to Knysna is insignificant. Instead, by removing the bypassing traffic from the centre of town, there is reason to believe that Knysna will actually gain business. Sectors such as tourism would do much better with a reduction in congestion.



In the quantitative sections, both a financial and an economic analysis were conducted. The financial analysis focused only on the highway alternatives. As may be expected, the Short Route was found to be the better option. This was because the total financial cost was lower which meant that toll fees were lower. However, if in the long term, additional costs need to be incurred under the Short Route in order to construct a new route from Buffelsvermaak to Eastford along the ‘Proposed’ alignment (as argued by SANRAL), the overall cost of Short Route will, in fact, be more expensive. The implications this will have on toll fees is not included in this study. The economic cost-benefit analysis found that the Proposed Route was a far better alternative than either the Short Route or the Do Nothing (Do-nothing) option. This analysis evaluated the relative costs that the road user faced under each of the alternatives. Overall, VOCs, time costs and accident costs were much lower over the project’s life for the Proposed Route than for the other two alternatives. For the Proposed Route, there were several options for the bridge over the Knysna River. Following the environmental studies, it is suggested that the short bridge option be used as it has the lowest cost and does not result in significantly higher environmental impacts on the estuary and lagoon than the other more expensive bridge options. With respect to the relative impact of the cost of tolls of the various toll plaza site options, the Groenvlei option would do much to reduce opposition to the toll highway from west-bank residents, and would be likely to result in lower administrative costs to SANRAL or the concessionaire in comparison to the Eastford Plaza option. Thus, it is recommended that the Groenvlei option be used as the west-bound plaza site for the Short Route. There would also be some economic benefits to opting for the Groenvlei plaza for the ‘Proposed’ route as it would reduce toll fees on the residents and visitors to Buffelsbaai (including Knysna residents and visitors who make regular use of this beach area). There are no differences in the toll cost impacts of the two east-bound toll plaza sites – Brackenhill and Springfield. The economic analysis showed clearly that the Do Nothing option is the least favourable. In fact, it is the opinion of the consultants that to follow the Do Nothing alternative would result in significant negative impacts on the economy of Knysna. In terms of the economic rankings, all the indicators show that the Proposed Route is the preferable option. This is followed closely by the Short Route option. Table 9.17 restates the various indicators for the two routes. Table 9.17: Economic Indicators IRR B/C Ratio NPV (R'm) Short Route 60.7% 21.5 22,063.4 Proposed Route 65.9% 22.6 24,146.5 As indicated in Table 9.18, most of the economic impacts are general ones that have no implications for the choice of route for the highway. The only economic impacts that are differentiated by route relate to the bridge options over the Knysna River (in the western section of the highway) and the forestry sector which is limited to the eastern section of the highway. In the case of two of the bridge options, the cost of building a new bridge across the Knysna River is less than the cost of widening White bridge and constructing a viaduct across the flood plain. The third – the cable stayed bridge option – is more expensive than widening White bridge and constructing a viaduct across the flood plain. The expense of having to construct the viaduct for the Short Route substantially increases the costs of this route, and reduces the cost differential between the two routes. In the forestry case, the Proposed Route is much longer and would have greater impacts on this sector. However, these forestry impacts are of moderate to low significance.



Table 9.18: Summary of the Significance of the Economic Impacts of the Knysna Toll Highway (without Mitigation). Impacts Proposed Short Do

Nothing Section

of Highway

1 Increased GDP

Moderate Moderate N/A general

2 Employment Moderate Moderate N/A general 3 Transport

costs High + High + High - general

4 Tourism-business

High + High + High - general

5 Property prices

Low - Low - Mod - central

6 Tolls for Sedgefield residents

High - High - N/A general

7 Tolls on west bank residents

N/A Moderate - or Moderate + N/A general

8 Toll costs of Knysna residents

Moderate - Moderate - or Moderate + N/A general

9 Forestry Sector

Moderate - Low - N/A eastern

10 Main Interchanges

Eastford: Moderate - Salt River: Moderate - N/A central

Short Bridge Option: Neutral N/A N/A western Long Bridge Option: Low - N/A N/A western Cable Stay Option: Low - N/A N/A western

11 Knysna River Bridges

N/A White Bridge + Viaduct: Low - N/A western 12 Salt River

Bridge Low - Low - N/A central

13 Resettlement Costs

Low - Low - N/A central

14 Land for housing

Moderate + Moderate + N/A central

15 Land expropriation

Low - Low - N/A all

Thus, although the Short Route results in marginally lower toll fees in the medium term, the Proposed Route results in the lowest total costs to the road users. Thus, this study finds that the economic ranking of the three alternatives should be: 1. Proposed Route 2. Short Route 3. Do Nothing.



10 CUMULATIVE IMPACTS Cumulative Impacts or effects have been defined as “…changes to the environment that are caused by an action in combination with other past, present and future human actions” (Hegmann et al. 1999 as cited on page 5 in DEAT 2004). The DEAT guidelines for Environmental Impact Assessments highlight the need to assess cumulative impacts as part of the EIA process. Consequently, the discussion which follows provides an assessment of the potential for cumulative impacts associated with the Knysna Toll Highway Project. As illustrated in table 10.1 below, eight different types of cumulative effects are generally recognised. In the case of the Knysna Toll Highway project there is the potential for both direct and indirect cumulative impacts; these are discussed separately below. Table 10.1: Types of cumulative effects. (see table 1 in DEAT 2004, pg 6) Type Characteristic Example Time crowding Frequent and repetitive impacts Forest harvesting rates exceeds

regrowth Time lags Delayed effects Bioaccumulation of mercury Space crowding High spatial density of effects Pollution discharge into stream from non-

point sources. Cross-boundary Effects occur away from the

source Atmospheric pollution and acid rain

Fragmentation Change in landscape pattern Fragmentation of indigenous habitats Compounding effects

Effects arising from multiple sources or pathways

Synergism amongst pesticides

Indirect effects Secondary effects Developments following construction of a new highway

Triggers and thresholds

Fundamental changes in system functioning and structure

Climate change

10.1 Direct cumulative impacts 10.1.1 Compounded impacts In the case of the SANRAL’s proposal to develop a Knysna Toll Highway, the aquatic study of the estuary found no significantly high impacts on the estuary directly associated with the construction of the bridge options. However, there was concern about the indirect impact of erosion in the catchment on the estuary. The erosion study also indicated that the highway will potentially have a significant erosion impact, particularly on the western section of the Proposed route where there are deep cover sands and steep slopes. Erosion in this area could result in sedimentation, deposition and water quality impacts on the river and estuary. Given the uniqueness and importance of the Knysna estuary, such impacts are of considerable concern. So the potential for downstream impacts on the estuary increases the importance of avoiding erosion impacts or effectively mitigating and managing them to avoid secondary impacts on the estuary. Another case of cumulative impacts arises in the Knysna Highway case due to the impacts of some of the mitigation measures proposed by the various specialist studies. The noise assessment for instance, recommends that noise barriers be constructed along the highway and link roads in suburban areas to reduce the noise to acceptable levels. Some of these barriers may need to be very high (5m). This in turn may have significant visual impacts that have not been factored into the analysis undertaken by the visual assessment specialists. It may increase the visual impacts but, if these barriers are developed in an appropriate manner that blends in with the surrounding landscape, they could reduce the visual impact in some areas. The construction of



such high barriers will also increase the costs of the highway. While this will increase the economic benefits of the highway, it may also increase the toll fees and the secondary economic impacts these may have. Unfortunately, it is not possible at this stage to develop accurate estimates of the costs of such barriers, as further studies would be needed to calculate the exact size, location and length of such barriers. The additional measures that will be needed to prevent erosion during the construction phase, and to manage them during the operational phase, will also add to the costs of the highway. 10.1.2 Cumulative effects over time Similarly, while the impacts of any particular route alternative may not be too significant to be of concern, the impacts of all the routes being realised at different points in time could become very significant. For example, if the decision making process results in the highway proposal not proceeding at this stage, then this could result in the impacts of the ‘Do Nothing’ option being realised. However, as a result of traffic congestion problems the highway project could be initiated again in the next five years and if this succeeds in the ‘Short Route’ being developed, then all of the impacts of this route would also be realised. Then another 15-20 years later, if as a result of significant growth in the Knysna area the western and eastern sections of the ‘Proposed Route’ are developed, then the impact of this alternative will also be realised. In this scenario the impacts of all the highway route alternatives will be realised and will have a significant cumulative effect. These cumulative impacts could be avoided if a strategic decision was made to resolve Knysna’s long term traffic problems at the outset. 10.2 Indirect cumulative impacts The need for the highway arises from increased population and economic growth, which increases traffic volumes and eventually results in congestion as the existing road infrastructure reaches carrying capacity. The development of a highway, and the associated progress with implementing the Municipality’s Traffic Management Plan (which will be achieved through upgrading of the three intersections in the CBD as part of the highway development), will allow Knysna to continue growing physically and economically. In other words it will allow more economic activity to take place and more people to live in and visit Knysna. The highway will also provide benefits to other areas far beyond the Knysna region due to the strategic position Knysna occupies on the national road network. The cumulative environmental effects of the proposed Highway project will also be a consequence of the indirect effects it will have on economic growth. While economic growth is usually seen as a good thing and is the central political goal for most countries, it normally has negative impacts on the natural environment. It results in more natural resources being lost or used, and more pollution and degradation occurring. In the case of the highway, it will allow more economic activity to take place in the Knysna area and more people to live and visit there. This in turn will result in:

• the clearing of more natural vegetation to make way for roads, pathways, infrastructure, buildings and gardens etc.

• the loss of suitable habitat for indigenous and endangered species, • the fragmentation of vegetation types and populations • the loss of threatened and endangered plant and animal species • increased risk of fires • increased risk of pollution • erosion due to vegetation removal • sedimentation in the tributaries and the estuary • changes to water quality and quantity in the river

Economic growth will also have other negative indirect social impacts due to changes in the landscape, and increases in the number of people exposed to visual and noise impacts. One of the benefits of economic growth will be the reduction in the financial burden associated with tolls due to the larger number of road users and the higher incomes.



The magnitude of these impacts will obviously depend on whether they are managed to ensure sustainability and how well they are managed. Government and municipal planning processes are designed to address these issues but capacity constraints can undermine the effectiveness of management strategies. However, economic growth normally increases human, physical and financial capital and could therefore increase local capacity to manage environmental impacts as they have done in most other developed parts of the world. It is just unfortunate that this capacity arrives after most of the damage has already been done.

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8 IMPACTS AND MITIGATION: THE NATURAL ENVIRONMENT N2 Bypass EIR (Pg 109- 294).pdf · 8 IMPACTS AND MITIGATION: THE NATURAL ENVIRONMENT ... the central section which is common to both