FRESHWATER ECOSYSTEMS CONSTRAINTS ANALYSIS: PROPOSED LOW ... · freshwater ecosystems constraints analysis: proposed low-cost housing development on erven 10509 and ca597-15-re, philippi

FRESHWATER ECOSYSTEMS CONSTRAINTS ANALYSIS: PROPOSED LOW-COST HOUSING DEVELOPMENT ON ERVEN

10509 AND CA597-15-RE, PHILIPPI (CITY OF CAPE TOWN)

The Freshwater Consulting Group

April 2016

Report prepared for:

Guillaume Nel Environmental ConsultantsPO Box 2632Paarl 7620

Document title : Freshwater Ecosystems Constraints Analysis: Proposed Low-cost Housing Development on Erven 10509 and CA597-15-RE, Philippi (City of Cape Town)

Authors : Johann Kilian Cand.Sci.Nat. Tumisho Ngobela Cand.Sci.Nat.

Reviewed by : Dean Ollis Pr.Sci.Nat.

Project : Sheffield Road

Status of report : Final

Report date : 8 April 2016

Contact person:

Dean Ollis

Unit #23, Imhoff FarmKommetjie Main Road

Kommetjie 7975Cell: 072 377 7006

Email: [email protected]

Consulting Group

Freshwater

Freshwater Ecosystems Constraints Analysis: Erven 10509 and CA597-15-RE, Philippi

TABLE OF CONTENTS

1. INTRODUCTION.............................................................................................................................11.1. Background.................................................................................................................................11.2. Terms of Reference.....................................................................................................................2

2. APPROACH TO AND LIMITATIONS OF THE SPECIALIST INVESTIGATION.........................................22.1. Approach....................................................................................................................................22.2. Limitations..................................................................................................................................3

3. BIOPHYSICAL OVERVIEW OF STUDY AREA.....................................................................................4

4. DESCRIPTION OF PROPOSED SITE AND POTENTIALLY AFFECTED FRESHWATER ECOSYSTEMS........54.1. Site description...........................................................................................................................54.2. Freshwater ecosystems on the site.............................................................................................6

5. DESCRIPTION OF PROPOSED DEVELOPMENT................................................................................7

6. CONCLUSIONS...............................................................................................................................8

7. REFERENCES..................................................................................................................................8

The Freshwater Consulting Group


1. INTRODUCTION

1.1. Background

The following information regarding the proposed development was received from the proponent (provided here verbatim with minor editing for clarity).

The Housing Development Agency (HDA) is currently in the process of transferring the HDA-owned property, Erf 10509 situated in Philippi, to the Western Cape Department of Human Settlements for the establishment of permanent medium-density housing to accommodate excess approved beneficiaries of the Boystown project as part of the N2 Gateway National Priority Project.

Figure 1: Locality Map for Consolidated Erf 10509, Philippi, City of Cape Town, Western Cape

Guillaume Nel Environmental Consultants (GNEC) have been appointed to coordinate the environmental authorisation process that is required for the proposed development. The Freshwater Consulting Group (FCG) has, in turn, been sub-contracted to provide freshwater ecological input into the environmental assessment.

The Freshwater Consulting Group 1


1.2. Terms of Reference

The specific Terms of Reference for FCG’s input into the environmental assessment process for the proposed low-cost, medium-density residential development on Erven 10509 and CA597-15-RE, Philippi, were to compile an Aquatic Constraints Analysis Report for the property on which the residential development is proposed to be constructed.

2. APPROACH TO AND LIMITATIONS OF THE SPECIALIST INVESTIGATION

2.1. Approach

The approach taken to meeting the above-mentioned Terms of Reference was as follows: Review of all available documentation and plans for the proposed project, including

the EIA Application by GNEC (GNEC 2015) and the botanical report by Bergwind (Emms 2015).

Examination of relevant conservation/biodiversity plans to note whether any rivers or wetlands of regional or local conservation importance have been identified on or in close proximity to the proposed site – these included the mapping products of the National Freshwater Ecosystem Priority Areas (NFEPA) project and the City of Cape Town's Biodiversity Network and associated Wetlands Map.

Examination of relevant maps, aerial photographs and Google Earth imagery of the study area, including historical aerial photographs of the study area dating back to the 1940's.

Preparation of a preliminary, desktop-based map of freshwater ecosystems potentially present in the vicinity of the site using Geographical Information Systems (GIS) software.

Completion of a site visit (on 2 March 2016) to visually scan the proposed site, and to identify and map the freshwater ecosystems that were confirmed to be present on or adjacent to the site, using standard field procedures.

Compilation of a ground-truthed map showing the location of the freshwater ecosystems confirmed to be present on or adjacent to the proposed site.

Determination of the conservation importance of the freshwater ecosystems identified to be present on the site, using the criteria for categorising the conservation importance of wetlands and other freshwater ecosystems developed by FCG (after Ewart-Smith & Ractliffe 2002) as summarised in Table 1.

Preparation of the current report, which summarises the findings of the constraints analysis relating to freshwater ecosystems for the proposed site.



Table 1: Criteria used to assign low, moderate or high conservation importance to the potentially affected wetlands and other freshwater ecosystems [from Ewart-Smith & Ractliffe (2002)]

2.2. Limitations

The following limitations apply to the constraints analysis presented in this report: No water quality data were collected for the potentially affected freshwater ecosys-

tems on the site, but it is unlikely that the collection of such data would have changed any of the findings;

No faunal data were collected for the potentially affected freshwater ecosystems but it is unlikely that these ecosystems are providing habitat for any fauna of conserva-tion significance because of the artificial nature of the systems and the highly dis-turbed ecological state of the site ; and

This study provides an assessment of the constraints relating to freshwater ecosys-tems, and not a comprehensive assessment of the potential impacts on freshwater ecosystems.



3. BIOPHYSICAL OVERVIEW OF STUDY AREA The geology of the area is mainly made up of Tertiary to recent calcareous sands of marine origin and overlaying metasediments of the Tygerberg Formation (Rebelo et al. 2006). The landscape of the Cape Flats, which the study area forms part of, has been largely altered (i.e. levelled), with extensive dune fields having undergone transformation due to sand-mining and development of housing and other infrastructure (Emms 2015).

According to the most recent national vegetation map (Mucina & Rutherford 2006), the proposed site is located in an area that would have naturally consisted of Cape Flats Dune Strandveld. Cape Flats Dune Strandveld is categorised as an Endangered terrestrial vegetation type on the National List of Threatened Ecosystems published in terms of the National Environmental Management: Biodiversity Act (Act No. 10 of 2004) (Government Notice 1002 of 9 December 2011), due the high number of threatened plant species associated with this vegetation type and the high degree of habitat transformation.

The proposed site is situated within the South Western Coastal Belt Ecoregion (after Kleynhans et al. 2005). The topography of this ecoregion is dominated by plains with a moderate to low relief, and there is a predominance of slopes with a gradient of <5%. The most dominant vegetation type in the ecoregion is Renosterveld, although significant areas of Fynbos are also present. One of the more significant rivers that flow through this ecoregion is the Kuils River.

The study area is situated in DWS Quaternary Catchment G22D. The modelled hydrological characteristics of this Quaternary Catchment are as follows (after WRC 2008):

Mean Annual Precipitation (MAP) = 823 mm [strongly seasonal, mostly in winter] Mean Annual Evaporation (MAE) = 1400 mm Mean Annual Runoff (MAR) = 57 X 106 m3

No naturally-occurring (or artificial) wetlands were mapped on or adjacent to the proposed site by the NFEPA project and the site does not fall with the City of Cape Town's Biodiversity Network (May 2015 edition). The City’s Wetlands Map (May 2015 edition) shows the south western corner as a storm water pond that has been categorised as an OESA (Other Ecological Support Area). This feature was, however, found to be incorrectly mapped during the site assessment by FCG (see Section 4.2).



was, however, only observed to be present on the highest points of the site. It is likely that this upper layer has been stripped from the rest of the site during sand mining activities in the past. The soil layer immediately below the white sand generally consists of brown-grey sand and this layer was the dominant soil found on the property. An E-horizon was observed to be present approximately 50 cm below the ground surface in the lower-lying parts of the site (typically within depressions), which generally consisted of whiteish-grey silty sand.

The vegetation currently present on the site has been described as “severely ecologically compromised pockets of Cape Flats Dune Strandveld” (Emms 2015). The botanical assessment by Emms 2015 concluded that, “Over 95% of the site is highly degraded to transformed. The site is also ecologically and spatially isolated. It is overrun with alien grasses and patches of Port Jackson Willow and is polluted with human faeces, cattle dung and litter. The conservation value of the habitat is considered to be very low. It is the specialist’s opinion the site is ideal for development since there would be no far-reaching conservation implications and threats to the Cape Flats Dune Strandveld ecosystem or threatened species.”

4.2. Freshwater ecosystems on the site

Five depressions were identified to be present on the site (Figure 3). These features are likely due to the transformation of the topography by historic sand mining and surrounding development.

The artificial depressions presumably collect water from precipitation and localised runoff, and from the rising of the water table during the wet season. The wetness regime is seasonally to permanently saturated, as was demonstrated by free water being encountered within 0.5 to 1 m of the surface in places at the time of the site visit (high summer) and the presence of poorly developed redoximorphic features (e.g. sparse mottling) in the soils of some of the depressions within 0.5 m of the surface. Presumably some of the depressions would be temporarily to seasonally inundated with standing water during and after rainfall events in the wet season (winter to spring). Most of the depressions were filled with domestic litter and building rubble at the time of the site visit by FCG.

The vegetation in the depressions is characterised and dominated by dense mats of Kikuyu Grass (Pennisetum clandestinum) and Kweek Grass (Cynodon dactylon). The grass is persisting and tolerant of existing cattle grazing, trampling and waterlogging. Isolated individuals of the indigenous wetland plant Juncus c.f. acutus were found in the artificial depressions, while Cyperus congestus (an indigenous sedge) was found in dense stands in the north-western depression on the site.



Figure 3: Map of excavated depressions on Consolidated Erf 10509, Philippi

The artificially-created depressions on the subject property were rated to be of low conservation importance, according to the criteria outlined in Table 1. The main reasons for the low conservation importance rating are that these non-natural features are considered to be providing limited aquatic habitat, and because the artificial depressions are highly degraded and substantially altered with no connectivity to other aquatic systems.

5. DESCRIPTION OF PROPOSED DEVELOPMENTThe proposal is to establish a low-cost, medium-density residential development on Erf 10509 (2.4814 ha) and Erf CA597-15-RE (3.183 ha). The two properties making up the proposed site will be consolidated under Erf 10509 (as shown on the locality map in Figure 1), with the entire development covering an area of approximately 5.7ha (57 000m2). Erf 10509 is currently bounded by low-to-medium density residential land-uses to the north, east and south, and informal residential structures to the west (opposite Sheffield Road).



6. CONCLUSIONSThe main conclusion of the freshwater ecosystems constraints assessment undertaken by FCG is that there are no naturally-occurring wetlands or any other freshwater ecosystems of particular conservation value present on site. The wet areas that were identified on the proposed development site are artificial depressions, presumably created through historic sand mining and the excavation of material from the site. The artificial depressions are highly degraded in terms of their vegetation, being dominated by Kikuyu and Kweek Grass. The proposed low-cost, medium-density housing development would thus only impact on what are considered to be highly degraded, artificial depressions with very low conservation value. It is, therefore, the professional opinion of FCG that there are no constraints from a freshwater ecological perspective that preclude against the proposed low-cost housing development on Consolidated Erf 10509.

7. REFERENCESEmms P (2015). Botanical Assessment for proposed low cost housing at Erf 10509, Philippi: N2 Gateway

National Housing Priority Project, City of Cape Town. Prepared by Bergwind Botanical Surveys & Tours for Guillaume Nel Environmental Consultants, December 2015.

Ewart-Smith JL and Ratcliffe SG (2002). Assessment of the Potential Impacts of the Proposed N1 / N2 Winelands Toll Highway Project on Aquatic Ecosystems. Specialist EIA Report to Crowther Campbell & Associates, on behalf of the National Roads Agency.

GNEC (2015). EIA Application: Proposed Construction and Establishment of a Low Cost Medium Density Housing Development and Associated Infrastructure on Erf 10509, Philippi, as part of the N2 Gateway National Priority Project. Prepared by Guillaume Nel Environmental Consultants (GNEC).

Kleynhans CJ, Thirion C and Moolman J (2005). A Level I River Ecoregion classification System for South Africa, Lesotho and Swaziland. Report No. N/0000/00/REQ0104. Resource Quality Services, Department of Water Affairs and Forestry, Pretoria.

Mucina L and Rutherford MC (eds) (2006). The Vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.

Ollis DJ, Snaddon CD, Job NM and Mbona N (2013). Classification System for Wetlands and other Aquatic Ecosystems in South Africa. User Manual: Inland Systems. SANBI Biodiversity Series 22. South African National Biodiversity Institute, Pretoria.

Rebelo AG, Boucher C, Helme N, Mucina L and Rutherford MC (2006). Fynbos Biome. In: Mucina L and Rutherford MC (eds.) The Vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.

Water Research Commission [WRC] (2008). Water Resources of South Africa, 2005 (WR2005). WRC Project No. K5/1491. Water Research Commission, Pretoria.


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FRESHWATER ECOSYSTEMS CONSTRAINTS ANALYSIS: PROPOSED LOW ... · freshwater ecosystems constraints analysis: proposed low-cost housing development on erven 10509 and ca597-15-re, philippi