Report on a Phase 1 Engineering Geological Investigation ...nalisustainabilitysolutions.co.za/wp-content/... · Civil Engineer or other suitably experienced specialist to overwrite

JLOUISVANROOYPr.Sci.Nat.PhD(Pret)FSAIEGMGSSAEngineeringGeologist POBox36786 MENLOPARK0102E-mail:[email protected] Tel:0832910938 Fax:0123498500

Preparedfor: CenturyPropertyDevelopment(Pty)Ltd.POBox70406Bryanston2021

Report 1553

Report on a Phase 1 Engineering Geological Investigation: Holding 104 Blue Hills AH, Midrand, Gauteng

December2015

Holding 104, Blue Hills

2015/12/21 ii J Louis van Rooy

1. INTRODUCTION.............................................................................................................................12. AVAILABLE INFORMATION.....................................................................................................13. SITE DESCRIPTION.....................................................................................................................1The investigated holding is located east along Mimosa Road from the R55 Main Road and is enclosed by Poplar Road along the west and Acacia Road along the east with access from Mimosa Road on the southern boundary, in Blue Hills Agricultural Holdings, Midrand (Figure 1, Appendix A)..........................................................14. METHOD OF INVESTIGATION.................................................................................................25. GEOLOGY........................................................................................................................................2

5.1 GENERAL........................................................................................................................................................25.2 SOIL PROFILE...............................................................................................................................................25.3 GROUNDWATER..........................................................................................................................................3

6. GEOTECHNICAL EVALUATION..............................................................................................36.1 ENGINEERING AND MATERIAL CHARACTERISTICS...................................................................46.2 SLOPE STABILITY AND EROSION........................................................................................................46.3 EXCAVATION CLASSIFICATION WITH RESPECT TO SERVICES............................................56.4 IMPACT OF THE GEOTECHNICAL CHARACTER OF THE SITE ON HOUSING DEVELOPMENTS.................................................................................................................................................5

7. SITE CLASSIFICATION AND FOUNDATION RECOMMENDATIONS........................58. CONCLUSIONS..............................................................................................................................69. REPORT PROVISIONS................................................................................................................710. REFERENCES.............................................................................................................................8

Table 1. Test pit summary Table 2. Indicator test results Table 3. Geological classification for urban development Table 4. Geotechnical Classification for Urban Development Table 5. Residential site class designations Table 6. Foundation design for buildings founded on heaving soils Table 7. Foundation design for buildings founded on collapsible soils

Table 8. Foundation design for buildings founded on compressible soils

APPENDIX A: FIGURES APPENDIX B: SOIL PROFILES APPENDIX C: SOIL PROFILE PHOTOGRAPHS APPENDIX D: LABORATORY TEST RESULTS APPENDIX E: SITE CLASS DESIGNATION TABLES

2015/12/21 J Louis van Rooy 1

J LOUIS VAN ROOY P O Box 36786 Pr.Sci.Nat. PhD(Pret) FSAIEG MGSSA MENLOPARK Engineering Geologist PRETORIA 0102

( C - 083 2910938 Report 1553/final [email protected] 21 December 2015 REPORT ON A PHASE 1 ENGINEERING GEOLOGICAL INVESTIGATION: HOLDING

104 BLUE HILLS A.H., MIDRAND, GAUTENG.

1. INTRODUCTION A Phase 1 Geotechnical Site Investigation was undertaken at the request of Johann Jordaan of Optical Town Planners on behalf of the client Century Property Developments (Pty) Ltd. for township establishment on Holding 104, Blue Hills Agricultural Holdings, Midrand, Johannesburg, Gauteng Province. The property is approximately 3 ha in surface area. The investigation was undertaken according to the SANS 634:2009 national standard as well as the Guidelines for Urban Engineering Geological Investigations (SAIEG & SAICE, 1997) for urban development on sites smaller than 10 hectares and included the excavation of trial pits, description of the soil profiles and soil sampling for laboratory testing. The objectives of the investigation were:

• To determine the geology and the relevant mechanical properties of the soil and rock horizons present on site.

• To give general foundation recommendations. • To comment on the excavation characteristics and possible uses of the materials

underlying the site for installation of services as well as for use in layer works in paving and roads.

• To comment on site water management aspects particularly pertaining to shallow groundwater or seepage.

The investigation excludes the following aspects, where applicable: • Flood lines and wetland delineation • Detailed hydrogeology • Assessment of dolomite stability and undermining.

2. AVAILABLE INFORMATION At the time of the investigation the 1: 250 000 Geological Sheet 2528 Pretoria, 1:50 000 Geological Sheet 2528CC Lyttelton, 1:50 000 topocadastral map 2528CC Centurion, site locality and a satellite image were available. The guideline and specification documents by the South African Institute of Engineering and Environmental Geologists and South African Institution for Civil Engineers (2002) were also used. 3. SITE DESCRIPTION The investigated holding is located east along Mimosa Road from the R55 Main Road and is enclosed by Poplar Road along the west and Acacia Road along the east with access from Mimosa Road on the southern boundary, in Blue Hills Agricultural Holdings, Midrand (Figure 1, Appendix A). There is a house with garden, swimming pool and various outbuildings in the north-eastern part of the holding with the remainder undeveloped. A previous dam is located near the south-western

Holding 104 Blue Hills

2015/12/21 2 J Louis van Rooy

corner and a number of large trees are present in the garden area surrounding the house, along the northern boundary and surrounding the dam area. The site slopes to the south, towards Mimosa Road, at approximately 3,5o (Figure 2, Appendix A). The site elevation is between 1 514 m in the south and 1 530 m above mean sea level on the northern boundary. The surrounding area is serviced by typical municipal services, although the roads surrounding the holding is dirt without any stormwater reticulation. 4. METHOD OF INVESTIGATION The fieldwork, entailing a site walkover, trial pitting and profile descriptions were conducted on 10 November 2015 during which time five trial pits were excavated by a JCB 3CX Tractor Loader Backhoe (TLB), which was supplied by Paul Heslop Plant Hire. The 5 profiles are regarded as being representative of the site conditions. The trial pit positions are indicated on a satellite image of the site (Figure 3, Appendix A). A registered Engineering Geologist inspected the excavation of the 5 trial pits and recorded the soil profiles using the standard procedures as recommended by AEG/SAIEG/SAICE (2002). The soil profiles are included in Appendix B and photographs of the test pits are attached in Appendix C. Five disturbed soil samples were retrieved from selected layers in some trial pits and submitted to Soillab (Pty) Ltd. of Pretoria for testing. Foundation indicator tests were performed on the disturbed samples to determine the particle size distribution and plasticity of the soil. The material was tested for foundation purposes and therefore the grading was carried out to 0,002 mm. Chemical analysis was also conducted on selected samples to test the potential corrosivity of the site materials. 5. GEOLOGY 5.1 GENERAL According to the 1:50 000 geological sheet 2528CC Lyttelton and 1:250 000 sheet 2528 Pretoria, the site is underlain by granite-gneiss and granite of the Johannesburg Granite Dome and consists of poorly exposed biotite tonalite, trondjhemite, granodiorite and migmatite varieties. This site is not underlain by dolomitic bedrock and a surface stability investigation is therefore not required. According to the geological maps and accompanied explanation no specific mineral deposits are present on the site. Some linear features, inferred from surface magnetic surveys, are indicated in the vicinity of the site, but no intrusions are specifically indicated within the site boundaries. The climatic N-value (Weinert, 1980) of the region is less than 5, which implies that chemical weathering is dominant. 5.2 SOIL PROFILE A brief description of the various soil horizons encountered in the trial pits excavated is given below with a summary in Table 1. The surficial transported horizon is on average 0.3 m thick and comprises of dry, greyish brown loose intact with open root channels clayey silty sand with coarse quartz gravel.



The typical pebble marker, regarded as the boundary between the upper transported and deeper residual materials, is present in all test pits but BH3 on the western boundary. Table 1: Test pit summary: Encountered depths of different materials (m) Test Pit Topsoil &

Colluvium Pebble Marker

Ferricrete Residual granite Weathered granite

Test pit depth (m)

BH1 BH2 BH3 BH4 BH5

0 – 0.16 0 – 0.40 0 – 0.30 0 – 0.40 0 – 0.20

0.16 – 0.27 0.40 – 0.54

0.40 – 0.60 0.20 – 0.47

0.30 – 0.44

0.27 – 0.45 0.54 – 1.27

0.60 – 1.00

0.45 – 1.60

0.47 – 0.80

1.60AR 1.27

0.44R 1.40R 0.80R

R-Refusal; AR – Approaching refusal; EOH – End of hole

The pebble marker is moist, greyish brown, loose, intact with open root channels, clayey silty sand with abundant sub-angular, translucent medium to coarse quartz gravel. All the test pits except BH3, on the central western boundary were terminated in residual to highly weathered granite at depth varying between 1,6 m and 0,8 m. Machine refusal was reached at 0,44 m in test pit BH3 on honeycomb ferricrete. The residual granite is typically moist, greyish brown mottled orange, speckled white, loose to medium dense, voided, clayey gravelly sand. The average depth to residual granite is 0,47 m. Highly weathered granite was exposed at 0,45 m in BH1 and 0,47 m in BH5 and is medium dense to dense and jointed coarse sand. 5.3 GROUNDWATER Shallow and/ or perched water tables will very likely be present at the site. Significant changes in moisture content may contribute to the anticipated movement behaviour of the site soils. During construction and after development, shallow perched water systems may develop yet further due to stormwater management practices and localised infiltration.

• No water seepage was encountered in any of the test pits. Waterlogged conditions or surface ponding following prolonged and intense precipitation events are, however, anticipated at the site, especially on the lower elevated southern parts.

• Ferruginization (resulting from alternating waterlogged and dried states and typically referring to the yellow to black discoloured soils) furthermore supports the notion of periodical waterlogged conditions of site soils. Test pit BH3 was terminated on honeycomb ferricrete where perching will occur. This is near the small earth dam where strong ferruginization is evident.

• Altering the soil profile in granitic terrain commonly affects the subsurface seepage. Design should incorporate the likelihood of enhanced shallow seepage due to localised infiltration, stormwater practices, etcetera.

RECOMMENDED ACTIONS: Drainage precautions are required to minimise differential movements and erosion. The installation of drains may prevent super-saturation of the site soils and minimise differential movements on surface level. If the site or a portion thereof is situated within the 1:100-year flood lines, or have been delineated as a wetland, it is the prerogative of the Civil Engineer or other suitably experienced specialist to overwrite the geotechnical recommendations for such portions. 6. GEOTECHNICAL EVALUATION The geotechnical appraisal is based on the field observations, local knowledge of the area, interpretations on site and available laboratory test results obtained during this investigation.



6.1 ENGINEERING AND MATERIAL CHARACTERISTICS The foundation indicator test results conducted on the samples retrieved from the various test pits on site are discussed below and summarised in Table 2. Table 2: Indicator test results Test pit

Depth (m)

Description Soil composition Atterberg Limits

LS %

GM Activity AASHO classification

Clay %

Silt %

Sand %

Gravel %

LL %

PI %

BH1 BH1 BH2 BH2 BH5

0-0.16 0.75 0.55 1.0

0-0.26

Topsoil Granite Granite Granite

Colluvium

6 5 5 8 8

20 19 9

20 22

66 57 27 47 63

8 19 59 25 7

20 27 22 20 22

6 9 9 6 7

3.0 4.0 5.0 3.0 3.0

1.16 1.39 2.16 1.42 1.02

Low Low Low Low Low

A-2/SM&SC A-2/SC A-2/SC

A-2/SM&SC A-4/SM&SC

LL – Liquid limit; PI – Plasticity index; LS – Linear shrinkage; GM – grading modulus; SP – slightly plastic; The results obtained indicate the following: • The colluvium typically grades as clay-gravel silty sand. It is slightly plastic with low potential

expansiveness and linear shrinkage and medium grading modulus. • The residual granite typically grades as silty gravelly sand with slight plasticity, low potential

expansiveness, low linear shrinkage and medium grading modulus.

• According to the AASHO and Unified Soil Classifications all the materials on site (A-2 and SM & SC) will be suitable subgrade but poor as subbase and not suitable for use as base course in roads pavement layers. Drainage will be poor and impervious when compacted, compressibility may be medium, but low when compacted and the shear strength will be good to fair when compacted and saturated. Typically the workability as a construction material is fair.

Mildly corrosive conditions are expected due to the acidic soils, although the electrical conductivity is low. The surficial transported horizons (colluvium and pebble marker) were described as loose in the upper < 0.6 m as well as having an open structure with open root channels. It is assumed that most of these soils will be removed prior to any foundations being placed. The residual granitic materials were generally described as being loose becoming dense in the less weathered horizons. All the residual horizons showed a voided structure. Generally loose consistencies ae correlated with allowable bearing capacities of less than 50 kPa. The applied load from a single storey masonry house may be assumed to be between 30 kPa and 50 kPa, which fall near the upper limit of the bearing capacity of the residual material. This disregards the effect of either heave or collapse. The structure in the granitic soil on site is generally described as voided, implying the existence of small openings. This indicates that additional volume change could occur due to compressible characteristics in the moist state while a collapsible grain structure may exist in the dry state. The general thickness of this horizon is more than 750 mm and results in an unfavourable situation according to Table 5 (Appendix E). 6.2 SLOPE STABILITY AND EROSION The slope gradients typically fall into the limits of 2o to 6o to the southwest and natural slope instabilities are not expected on this site. Due to the site gradient it is expected that cut to fill site preparation may be necessary and care must be taken to prevent differential settlements from occurring across the cut and fill parts of platforms. Concentrated runoff will cause erosion due to the sandy nature of the soils, especially after the vegetation has been cleared.



6.3 EXCAVATION CLASSIFICATION WITH RESPECT TO SERVICES Test pits were excavated by means of a JCB 3CX TLB to depths of between 0,44 m and 1,6 m with machine refusal in most of the test pits in residual and weathered granite. Excavation conditions are SOFT in accordance with SANS 1200D (1988) and SANS 634 (2009) to between 0,4 m and 1,0 m from surface where-after it becomes INTERMEDIATE. Refusal in test pit BH3 was reached in honeycomb Ferricrete at 0,44 m below surface. The extent of this Ferricrete horizon was not specifically mapped during this Phase 1 investigation. Test pit sidewalls were stable, however any excavation deeper than 1,5 m must be shored as is legally required. The upper site soils may be suitable for use as bedding and backfill in service trenches if the coarse fractions are removed. 6.4 IMPACT OF THE GEOTECHNICAL CHARACTER OF THE SITE ON HOUSING DEVELOPMENTS The impact of the geotechnical constraints on housing development (single storey masonry structures) may be evaluated according to Table 3, which is a summary of the general geotechnical constraints relevant to urban development (Partridge, Wood and Brink, 1993). The Class column indicates the severity of the specific constraints for this site. Table 3. Geological classification for urban development CONSTRAINT SITE CONDITION CLASS A Collapsible soil Any collapsible horizon or consecutive horizons with

a depth of more than 750 mm in thickness. 2

B Seepage Permanent or perched water table less than 1,5 m below ground surface

2

C Active soil Low soil heave potential expected. 1 D Highly compressible soil Intermediate soil compressibility expected. 2 E Erodability of soil Intermediate 2 F Difficulty of excavation to 1,5m

depth Rock or hardpan pedocretes between 10% and 40% of the total volume. 2

G Undermined ground No known undermined areas 1 H Instability in areas of soluble rock Soluble rocks not present 1 I Steep slopes Slopes between 2 and 6 degrees. 1 J Areas of unstable natural slopes Low risk. 1 K Areas subject to seismic activity This area is not a known natural seismic active zone.

Induced seismicity may occur. 1

L Areas subject to flooding No drainage features on site. n/a Class: 1 – Most favourable, 2 – Intermediate, 3 – Least favourable The main expected geotechnical constraints for this site are: • Collapsible and compressible soils on the granite soils. • Seasonal shallow perched groundwater tables and/or surface seepage. • Intermediate erodability of surficial soil horizons. • Intermediate excavation conditions in weathered granite horizons and honeycomb ferricrete. 7. SITE CLASSIFICATION AND FOUNDATION RECOMMENDATIONS The site has been classified into one Site Class Designation zone (Figure 3), based on the above constraints and the criteria as set out in the NHBRC (1999) guideline document of which the appropriate tables have been included in Appendix E. Site Class Designation – C1/2ABDEF – moderate collapse and consolidation settlement under



loading and/ or wetting over the entire soil profile, likely perched water system which may also develop post developmental; difficult excavation in weathered granite and Ferricrete horizons. Options based on the site class designation tables supplied in APPENDIX E are shown with respect to the recommended zoning of the site and the classification and foundation recommendations are based on results from this investigation and for present conditions. For heavier structures, improved foundations should be considered. For any required filling and levelling, proper foundation design will be required to minimise differential movement and to ensure suitable founding. The possible foundation options recommended for this site depend on the type of structure to be erected on site and the foundation depth (SAICE, 1995), and are suggested according to Table 7 (Appendix E):

Modified normal construction with good site drainage, Deep strip foundations, Soil raft.

These foundation recommendations are according to the Joint Structural Division (SAICE, 1995) Code of Practice for single storey masonry structures founded below the loose upper horizons (Tables 4 to 8, Appendix E). It is recommended that the structural engineers calculate the best economical foundation option for the proposed development based on the type of structure and the different available construction methods. 8. CONCLUSIONS The following pertains to the Phase 1 Engineering Geological (Geotechnical) Investigation for the proposed development of Holding 104 Blue Hills AH in Midrand, Gauteng. The site will be suitable for development if the geotechnical constraints are taken into account and the designs incorporate measures to accommodate the on site material properties and groundwater conditions. Appropriate foundation design, and building procedures will be necessary as listed in this report. The major geotechnical constraints for this site are: • Collapsible and compressible soils on the granite soils. • Seasonal shallow perched groundwater tables and/or surface seepage. • Intermediate erodability of surficial soil horizons. • Intermediate excavation conditions in weathered granite horizons and honeycomb ferricrete. The colluvium and residuum may settle additionally due to moderate collapsible soils, especially when loads are applied and significant increases in moisture content occur. The suggested foundations for single storey masonry dwelling units are modified normal strip footings, deep strip foundations or soil rafts to accommodate possible soil volume changes due to collapse. The upper sandy soils will generally be suitable as backfill, platform fill and subgrade for roads. The soils are slightly corrosive and cathodic protection or pipes other than steel is suggested. Good site drainage will be necessary as the occurrence of a perched water table is a reality. This may cause problems with dampness in surface structures and with installation of services. The saturation of the soil profile will also need special site drainage methods as this may lead to



additional collapse settlements under load and surface erosion. The installation of drains may prevent super-saturation of the site soils and minimise differential movements on surface level. The pits were backfilled by the TLB without proper compaction in layers. If structures are to be positioned over or across these pits proper compaction must be executed to prevent differential settlements from taking place. The same will apply to development across existing foundations, waste pits, dams, root areas of removed medium to large trees, and the two septic tanks identified on site. 9. REPORT PROVISIONS This investigation was executed along professional and accepted guidelines. This document has been prepared for the exclusive use of Century Property Development (Pty) Ltd. (“Client”) on the basis of instruction, information and data supplied by them. No warranty or guarantee, whether express or imply, is made by J L van Rooy with respect to the completeness or accuracy of any aspect of this document and no party, other than the “Client”, is authorised to or should place any responsibility or liability in any way whatsoever to any person or entity in respect of the whole or any part or parts of this document, or errors in or omissions from it, whether arising from negligence or any other basis in law whatsoever. Furthermore, copyright for this technical document vest with “Client” unless otherwise agreed to in writing. While every effort is made during the fieldwork phase to identify the different soil horizons, areas subject to a perched water table, areas of poor drainage, areas underlain by hard rock and to estimate their distribution, it is impossible to guarantee that isolated zones of poorer foundation materials, or harder rock have not been missed. For these reasons this investigation has sought to highlight areas of potential foundation, groundwater and excavation problems, to provide prior warning to the developer. Future development should be reassessed based on the specific conditions encountered. A competent person should inspect foundation excavations for future structures at the time of construction or the open service trenches, to determine the variance from the above assessment of the site. The present site zoning is based on the NHBRC Manual with the guideline site class designation specifically for single-storey masonry residential units. This investigation did not include floodline or wetland delineations and appropriately competent persons must be appointed to address these aspects. The required Phase II Geotechnical Investigation will be necessary to complete the per stand enrolment.

J.L. van Rooy Pr.Sci.Nat. 400239/83



10. REFERENCES Brink, A B A, 1979. Engineering Geology of Southern Africa. Volume 1. Building Publications. Silverton. Guidelines for soil and rock logging in South Africa. 2nd Impression 2002, eds. A.B.A, Brink and R.M.H. Bruin, Proceedings, Geoterminology Workshop organized by AEG, SAICE and SAIEG. 1990. Jennings, J.E.B., Brink, A.B.A., Williams, A.A.B., 1973. Revised guide to Soil Profiling for Civil Engineering Purposes in Southern Africa. The Civil Engineer in SA. p3-12. January 1973. Jennings, JE., & Knight, KA., 1975. A guide to construction on or with materials exhibiting additional settlement due to ‘collapse’ of grain structure. Proc. 6th Regional Conf. for Africa on SM & FE., Durban. Vol. 1, pp 99-105. Partridge, T.C., Wood, C.K., Brink, A.B.A., 1993. Priorities for urban expansion within the PWV metropolitan region: The primacy of geotechnical constraints. South African Geographical Journal, Vol 75, pp9-13. Stiff, et al, 1997. Guidelines for Urban Engineering Geological Investigations. South African Institute for Engineering and Environmental Geologists and the South African Institution of Civil Engineers. SAICE. 1995. Code of Practice: Foundations and superstructures for single storey residential buildings of masonry construction. Joint Structural Division, Johannesburg. First edition. Weinert, H.H., 1980. The natural road construction materials of southern Africa. Academica. Cape Town.

APPENDIX A: FIGURES AND REFERENCE TABLES

Figure 1: Locality Plan, Holding 104, Blue Hills A.H., Midrand.

\\

Figure 2: Elevation Model, Holding 104, Blue Hills A.H., Midrand.

Figure 3: Test Pit Positions and Geotechnical Zoning, Holding 104, Blue Hills, Midrand.

C2-2ABDEF

APPENDIX B: SOIL PROFILES

J LOUIS VAN ROOY Pr.Sci.Nat. PhD(Pret) FSAIEG MGSSA Engineering Geologist

0.0--0.16m

0.75m

Century Property Development (Pty) LtdHolding 104 BlueHills A.H.

HOLE No: BH1Sheet 1 of 1




JOB NUMBER: 1553JOB NUMBER: 1553

0.16

0.00

0.27

0.45

1.60

Dry, greyish brown, loose, intact with open root channels clayey siltyfine SAND with occasional sub-angular translucent quartz coarse gravel,Topsoil with roots.

Dry, greyish brown, loose, intact with open root channels clayey siltyfine SAND with abundant angular translucent quartz coarse gravel and Fe& Mn nodules, Pebble Marker with roots.

Dry brown mottled orange speckled yellow, medium dense, voidedclayey silty fine to coarse SAND. Residual granite.

Slightly moist light yellowish brown mottled range & black streaked whitedense gneissic banding and voided gravelly silty fine to coarse SAND.Highly weathered granite.

Scale1:10

NOTES1) Gradual TLB refusal.

2) No seepage.

3) No sidewall collapse.

4) Disturbed samples at 0.0--0.16m and 0.75m.

CONTRACTOR :MACHINE :

DRILLED BY :PROFILED BY :

TYPE SET BY :SETUP FILE :

Paul HeslopJCB 3CXPhill MarogaJLvanRooy

LOUIS.SET

INCLINATION :DIAM :DATE :DATE :

DATE :TEXT :

10/11/201530/12/2015 07:07C\DOT7000\1553DP.TXT

ELEVATION :X-COORD :Y-COORD :

1520m28.0918225.95712

dotPLOT 7019 PBpH67D04E J Louis van Rooy

HOLE No: BH1HOLE No: BH1HOLE No: BH1HOLE No: BH1


0.55m

1.0m







0.40

0.00

0.54

0.85

1.27

Moist, greyish brown, loose, intact with open root channels, clayey siltyfine to medium SAND with scattered sub-angular translucent quartzcoarse gravel. Colluvium with roots.

Moist, greyish brown, loose, intact with open root channels, clayey siltyfine to medium SAND with abundant sub-angular translucent quartzmedium to coarse gravel. Pebble Marker roots.

Moist, greyish brown mottled orange speckled white, loose, voided,clayey gravelly fine to coarse SAND with occasional angular gravel,Residual Granite. Roots.

Dry, white with occasional orange mottles dense, voided silty gravellyfine to coarse SAND. Residual granite.

Scale1:10

NOTES1) End of Hole.

2) Disturbed samples at 0.55m and 1.0m.


4) No seepage.





LOUIS.SET


DATE :TEXT :

10/11/201530/12/2015 07:07C\DOT7000\1553DP.TXT


1525m28.09182725.956528










0.30

0.00

0.44

Dry, greyish brown, loose, voided, clayey silty fine to coarse SAND,Colluvium, roots.

Dry, orange brown mottled black & orange dense to very dense, voidedhoneycomb FERRICRETE.

Scale1:10

NOTES1) TLB Refusal.

2) No sample.


4) No water seepage.





LOUIS.SET


DATE :TEXT :

10/11/201530/12/2015 07:07C\DOT7000\1553DP.TXT


1528m28.09132125.955902










0.20

0.00

0.40

0.60

1.00

Dry, greyish brown, loose, intact with open root channels clayey siltyfine SAND with occasional sub-angular translucent quartz coarse gravel,Topsoil with abundant roots.

Dry, greyish brown, medium dense, intact with open root channels, siltysandy fine to coarse GRAVEL, Colluvium with roots.

Moist, greyish brown, loose, intact with open root channels, clayey siltyfine to medium SAND with abundant sub-angular translucent quartzmedium to coarse gravel. Pebble Marker roots.

Moist, greyish brown mottled orange speckled white, loose, voided,clayey gravelly fine to coarse SAND with occasional angular gravel,Residual Granite. Roots.

Scale1:10

NOTES1) TLB refusal.

2) No sample.


4) No seepage.





LOUIS.SET


DATE :TEXT :

10/11/201530/12/2015 07:07C\DOT7000\1553DP.TXT


1531m28.0915225.955438




0.0--0.27m







0.20

0.00

0.47

0.60

Dry, greyish brown, medium dense, intact with open root channels, siltysandy fine to coarse GRAVEL, Colluvium with roots.

Moist, greyish brown, loose, intact with open root channels, clayey siltyfine to medium SAND with abundant sub-angular translucent quartzmedium to coarse gravel and large slightly weathered granite cobbles.Pebble Marker roots.

Moist, white mottled orange & yellow patches, medium dense, jointedsilty fine SAND, Highly weathered granite.

Scale1:10

NOTES1) End of hole.

2) Disturbed sample 0.0--0.27m.


4) No seepage.





LOUIS.SET


DATE :TEXT :

10/11/201530/12/2015 07:07C\DOT7000\1553DP.TXT


1531m28.09258525.955886



APPENDIX C: SOIL PROFILE PHOTOGRAPHS

Test pit BH1. Test pit BH2.

Test pit BH3. Test pit BH4.

Test pit BH5

APPENDIX D: LABORATORY TEST RESULTS

Sample No. 1 2

Soillab Sample No. 2015-S-1619-1 2015-S-1619-2 PROJECT : ERAND 104

Depth (m) 0 - 0.16 0.25 JOB No. : 2015-S-1619

Position BH 01 BH 01 DATE : 20-11-2015Material Description DARK GREY DARK REDDISH BROWN

FERRUGINISED FERRUGINISED

W/ GRANITE W/ GRANITE

SILTY SILTY

SAND SAND

Organic Material

Moisture (%) / Dispersion (%)

SCREEN ANALYSIS ( % PASSING) (TMH 1 A1(a) & A5)

63.0 mm 100 100

53.0 mm 100 100

37.5 mm 100 100

26.5 mm 100 100

19.0 mm 100 100

13.2 mm 98 99

4.75 mm 96 94

2.00 mm 92 81

0.425 mm 63 51

0.075 mm 29 29

HYDROMETER ANALYSIS ( % PASSING) (TMH 1 A6)

0.040 mm 21 18

0.027 mm 18 15

0.013 mm 13 10

0.005 mm 10 12

0.002 mm 6 5

% Clay 6 5

% Silt 20 19

% Sand 66 57

% Gravel 8 19

ATTERBERG LIMITS (TMH 1 A2 - A4)

Liquid Limit 20 27

Plasticity Index 6 9

Linear Shrinkage (%) 3.0 4.0

Grading Modulus 1.16 1.39

Uniformity coefficient 74 181

Coefficient of curvature 3.3 2.5

Classification A-2-4 (0) A-2-4 (0)

Unified Classification SM & SC SC

Soillab is a SANAS accredited Testing Laboratory.

Engineering Materials LaboratoryT +27 12 813 4900 E [email protected]

Soillab Pretoria

www.soillab.co.za

R54 revision 1

PARTICLE SIZE ANALYSIS

Chart Reference0 0.2 0.4 0.6 0.8 1 1.2

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80

PI o

f w

ho

le s

am

ple

Clay fraction of whole sample

POTENTIAL EXPANSIVENESS

0

20

40

60

80

100

Cu

mu

lati

ve %

passin

g

0.002 0.01 0.02 0.06 0.1 0.2 0.5 1.0 2.0 5.0 10 50 100

VERY HIGH

H

I

G

H

M

E

D

I

U

M

LOW

CLAY GRAVEL SILT SAND

0 0.2 0.4 0.6 0.8 1 1.20 0.2 0.4 0.6 0.8 1 1.2

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PLASTICITY CHART

HIDROMETER/1619-01.xls

Sample No. 3 4

Soillab Sample No. 2015-S-1619-3 2015-S-1619-4 PROJECT : ERAND 104

Depth (m) 0.85 1 JOB No. : 2015-S-1619

Position BH 02 BH 02 DATE : 20-11-2015Material Description LIGHT BROWN DARK YELLOWISH ORANGE

W/ GRANITE W/ GRANITE

SANDY GRAVELLY

GRAVEL SAND

Organic Material


SCREEN ANALYSIS ( % PASSING) (TMH 1 A1(a) & A5)

63.0 mm 100 100

53.0 mm 100 100

37.5 mm 100 100

26.5 mm 93 100

19.0 mm 87 100

13.2 mm 84 100

4.75 mm 61 93

2.00 mm 41 75

0.425 mm 27 51

0.075 mm 16 33

HYDROMETER ANALYSIS ( % PASSING) (TMH 1 A6)

0.040 mm 12 22

0.027 mm 10 18

0.013 mm 8 13

0.005 mm 7 10

0.002 mm 5 8

% Clay 5 8

% Silt 9 20

% Sand 27 47

% Gravel 59 25


Liquid Limit 22 20

Plasticity Index 9 6

Linear Shrinkage (%) 5.0 3.0

Grading Modulus 2.16 1.42

Uniformity coefficient 164 162

Coefficient of curvature 2.6 1.1

Classification A-2-4 (0) A-2-4 (0)

Unified Classification SC SM & SC



Soillab Pretoria

www.soillab.co.za

R54 revision 1


Chart Reference0 0.2 0.4 0.6 0.8 1 1.2

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Sample No. 5

Soillab Sample No. 2015-S-1619-5 PROJECT : ERAND 104

Depth (m) 0-0.26 JOB No. : 2015-S-1619

Position BH 05 DATE : 2015-11-25Material Description DARK GREY

WEATHERED

GRANITE

SILTY

SAND

Organic Material Yes


SCREEN ANALYSIS (% PASSING) (TMH 1 A1(a) & A5)

63.0 mm 100

53.0 mm 100

37.5 mm 100

26.5 mm 100

19.0 mm 100

13.2 mm 100

4.75 mm 97

2.00 mm 93

0.425 mm 69

0.075 mm 36

HYDROMETER ANALYSIS (% PASSING) (TMH 1 A6)

0.040 mm 23

0.027 mm 19

0.013 mm 14

0.005 mm 10

0.002 mm 8

% Clay 8

% Silt 22

% Sand 63

% Gravel 7


Liquid Limit 22

Plasticity Index 7

Linear Shrinkage (%) 3.0

Grading Modulus 1.02

Uniformity coefficient 49

Coefficient of curvature 2.2

Classification A-4 (0)

Unified Classification SM & SC

R54 revision 1


Chart Reference



Soillab Pretoria

www.soillab.co.za

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R26 revision 1


Engineering Materials Laboratory T +27 12 813 4900 E [email protected]

Soillab Pretoria www.soillab.co.za

Client: J LOUIS VAN ROOY

Project: ERAND 104

Project No.: 2015-S-1619

Date: 2015-12-02

pH & CONDUCTIVITY - TMH 1 A20 & A21T

Soillab No. Sample Position

Depth (m)

pH Electrical

Conductivity S/m

2015-S-1619-03 BH2 0.55 4.74 0.0065

APPENDIX E: SITE CLASS DESIGNATION TABLES

TABLE 4. GEOTECHNICAL CONSTRAINTS IN URBAN DEVELOPMENT (SANS 634:2012) CONSTRAINT DESCRIPTOR

DESCRIPTION 1 (most favourable) 2 (intermediate) 3 (least favourable)

A Collapsible soil

Any collapsible horizon or consecutive horizons totalling depth of less than 750 mm in thickness

Any collapsible horizon or consecutive horizons totalling depth of more than 750 mm in thickness

n/a

B Seepage

Permanent or perched water table more than 1.5 m below ground surface

Permanent or perched water table less than 1.5 m below ground surface

Swamps and marshes

C Active soil Low soil-heave potential anticipated

Moderate soil-heave potential anticipated

High soil-heave potential anticipated

D Highly compressible soil

Low soil compressibility anticipated

Moderate soil compressibility anticipated

High soil compressibility anticipated

E Erodibility of soil soil Intermediate High

F Difficulty of excavation to 1.5 m depth

Scattered or occasional boulders less than 10% of total volume

Rock or hardpan pedocretes between 10% and 40% of total volume

Rock or hardpan pedocretes more than 40% of total volume

G Undermined ground

Undermining at a depth greater than 200 m below surface

Old undermined areas to a depth of 200 m below surface

Mining within less than 200 m of surface with total extraction

H Stability (dolomite land) Possibly stable Potentially instable Known sinkholes and

dolines

I Steep slopes 2-6 degrees < 2 degrees or 6-18 degrees > 18 degrees

J Unstable natural slopes Low risk Intermediate risk High risk

K Seismic activity 10% probability of an event less than 100 cm/s2 in 50 years

Mining-induced seismicity > 100 cm/s2

Natural seismicity > 100 cm/s2

L Flooding n/a Adjacent to known drainage or channel with slope < 1%

Areas within drainage channel or floodplain

(After Partridge, Wood & Brink, 1993)

Table 5. RESIDENTIAL SITE CLASS DESIGNATIONS (SAICE, 1995)

TYPICAL FOUNDATION MATERIAL

CHARACTER OF FOUNDING MATERIAL

EXPECTED RANGE OF TOTAL SOIL

MOVEMENTS (mm)

ASSUMED DIFFERENTIAL

MOVEMENT (% OF TOTAL)

SITE CLASS

Rock (excluding mud rocks which exhibit swelling to some depth)

STABLE NEGLIGIBLE - R

Fine-grained soils with moderate to very high plasticity (clays, silty clays, clayey silts and sandy clays)

EXPANSIVE SOILS < 7,5 7,5 – 15 15 – 30

> 30

50% 50% 50% 50%

H H1 H2 H3

Silty sands, sands, sandy and gravelly soils

COMPRESSIBLE AND POTENTIALLY COLLAPSIBLE SOILS

< 5,0 5,0 – 10

> 10

75% 75% 75%

C C1 C2

Fine-grained soils (clayey silts and clayey sands of low plasticity), sands, sandy and gravelly soils

COMPRESSIBLE SOIL < 10 10 – 20

> 20

50% 50% 50%

S S1 S2

Contaminated soils Controlled fill Dolomitic areas Land fill Marshy areas Mine waste fill Mining subsidence Reclaimed areas Very soft silt/silty clays Uncontrolled fill

VARIABLE VARIABLE P

NOTES: 1. The classifications C, H, R and S are not intended for dolomitic area sites unless specific investigations are carried out to

assess the stability (risk of sinkholes and doline formation) of the dolomites. Where this risk is found to be acceptable, the site shall be designated as Class P (dolomitic areas).

2. Site classes are based on the assumption that differential movements, experienced by single-storey residential buildings, expressed as a percentage of the total movements are equal to about 50% for soils that exhibit expansive or compressive characteristics and 75% for soils that exhibit both compressible and collapse characteristics. Where this assumption is incorrect or inappropriate, the total soil movements must be adjusted so that the resultant different movements implied by the table is equal to that which is expected in the field.

3. In some instances, it may be more appropriate to use a composite description to describe a site mote fully e.g. C1/H2 or S1 and/or H2. Composite Site Classes may lead to higher differential movements and result in design solutions appropriate to a higher range of differential movement e.g. a Class R/C1 site. Alternatively, a further site investigation may be necessary since the final design solution may depend on the location of the building on a particular site.

4. Where it is not possible to provide a single site designation and a composite description is inappropriate, sites may be given multiple descriptions to indicate the range of possible conditions e.g. H-H1-H2 or C1-C2.

5. Soft silts and clays usually exhibit high consolidation and low bearing characteristics. Structures founded on these horizons may experience high settlements and such sites should be designated as being Class S1 or S2 as relevant and appropriate.

6. Sites containing contaminated soils include those associated with reclaimed mine land, land down-slope of mine tailings and old land fills.

7. Where a site is designated as Class P, full particulars relating to the founding conditions on the site must be provided. 8. Where sites are designated as being Class P, the reason for such classification shall be placed in brackets immediately

after the suffix – i.e. P(contaminated soils). Under certain circumstances, composite description may be more appropriate – e.g. P(dolomite areas)-C1.

9. Certain fills may contain contaminates which present a health risk. The nature of such fill should be evaluated and should be clearly demarcated as such.

Table 6. FOUNDATION DESIGN, BUILDING PROCEDURES AND PRECAUTIONARY MEASURES FOR SINGLE-STOREY RESIDENTIAL BUILDINGS FOUNDED ON EXPANSIVE SOIL (SAICE, 1995)

SITE CLASS

ESTIMATED TOTAL

SETTLEMENT (mm)

CONSTRUCTION TYPE

FOUNDATION DESIGN AND BUILDING PROCEDURES

H <7,5 Normal - Normal construction (strip footing or slab-on-the-ground foundations)

- Site drainage and service/plumbing precautions recommended H1 7,5 – 15 Modified normal

Soil raft

- Reinforced strip footings - Articulation joints at all internal/external doors and openings - Light reinforcement in masonry - Site drainage and service/plumbing precautions - Remove all or part of expansive horizon to 1,0 m beyond the

perimeter of the structure and replace with inert backfill, compacted to 93% MOD AASHTO density at –1% to +2% of optimum moisture content.

- Normal construction with lightly reinforced strip footings and light reinforcement in masonry if residual movements are 7,5mm, or construction type appropriate to residual movements.

- Site drainage and service/plumbing precautions. H2 15 – 30 Stiffened or cellular

raft Piled construction Split construction Soil raft

- Stiffened or cellular raft with articulation joints or lightly reinforced masonry.

- Site drainage and service/plumbing precautions. - Piled foundations with suspended floor slabs with or without

ground beams. - Site drainage and service/plumbing precautions. - Combination of reinforced brickwork/block work and full

movement joints. - Suspended floors of fabric-reinforced ground slabs acting

independently from structure. - Site drainage and service/plumbing precautions. - As for H1.

H3 > 30 Stiffened or cellular raft Piled construction Soil raft

- As for H2 - As for H2 - As for H1

NOTES: 1. Differential heave assumed to equal 50% of total heave. 2. The relaxation of some of these requirements, e.g. the reduction or omission of steel or articulation joints, may

result in a Category 2 level of expected damage.

Table 7. FOUNDATION DESIGN, BUILDING PROCEDURES AND PRECAUTIONARY MEASURES FOR SINGLE-STOREY RESIDENTIAL BUILDINGS FOUNDED ON HORIZONS SUBJECT TO BOTH CONSOLIDATION AND COLLAPSE SETTLEMENT (SAICE, 1995)

SITE CLASS

ESTIMATED TOTAL

SETTLEMENT (mm)

CONSTRUCTION TYPE


C <5 Normal - Normal construction (strip footing or slab-on-the-ground foundations) - Good site drainage

C1 5 – 10 Modified normal Compaction of in situ soils below individual footings Deep strip foundations Soil raft

- Reinforced strip footings - Articulation joints at some internal and all external doors - Light reinforcement in masonry - Site drainage and service/plumbing precautions - Foundation pressure not to exceed 50 kPa - Remove in situ material below foundations to a depth and width of

1,5 times the foundation width or to a competent horizon and replace with material compacted to 93% MOD AASHTO density at –1% to +2% of optimum moisture content.

- Normal construction with lightly reinforced strip foundations and light reinforcement in masonry.

- Normal construction with drainage requirements. - Founding on a competent horizon below the problem horizon - Remove in situ material to 1,0m beyond perimeter of building to a

depth and width of 1,5 times the widest foundation or to a competent horizon and replace with material compacted to 93% MOD AASHTO density at –1% to +2% of optimum moisture content.

- Normal construction with lightly reinforced strip footings and light reinforcement in masonry.

C2 >10 Stiffened strip footings, stiffened or cellular raft Deep strip foundations Compaction of in situ soils below individual footings Piled or pier foundations Soil raft

- Stiffened strip footing or stiffened or cellular raft with articulation joints or solid lightly reinforced masonry.

- Bearing pressure not to exceed 50kPa. - Fabric reinforcement in floor slabs. - Site drainage and service/plumbing precautions. - As for C1 but with fabric reinforcement in floor slabs - As for C1. - Reinforced concrete ground beams or solid slabs on piled or pier

foundations. - Ground slabs with fabric reinforcment. - Good site drainage. - As for C1.

NOTES: 1. Differential settlement assumed to equal 75% of total settlement 2. The relaxation of some of these requirements, e.g. the reduction or omission of steel or articulation joints, may

result in a Category 2 level of expected damage.

Table 8. FOUNDATION DESIGN, BUILDING PROCEDURES AND PRECAUTIONARY MEASURES FOR SINGLE-STOREY RESIDENTIAL BUILDINGS FOUNDED ON HORIZONS SUBJECT TO CONSOLIDATION SETTLEMENT (SAICE, 1995)

SITE CLASS

ESTIMATED TOTAL

SETTLEMENT (mm)

CONSTRUCTION TYPE


S 10 Normal - Normal construction (strip footing or slab-on-the-ground foundations) - Good site drainage

S1 10-20 Modified normal Compaction of in situ soils below individual footings Deep strip foundations Soil raft

- Reinforced strip footings - Articulation joints at some internal and all external doors - Light reinforcement in masonry - Site drainage and service/plumbing precautions - Foundation pressure not to exceed 50 kPa - Remove in situ material below foundations to a depth and width of

1,5 times the foundation width or to a competent horizon and replace with material compacted to 93% MOD AASHTO density at –1% to +2% of optimum moisture content.

- Normal construction with lightly reinforced strip foundations and light reinforcement in masonry.

- Normal construction with drainage requirements. - Founding on a competent horizon below the problem horizon - Remove in situ material to 1,0m beyond perimeter of building to a

depth and width of 1,5 times the widest foundation or to a competent horizon and replace with material compacted to 93% MOD AASHTO density at –1% to +2% of optimum moisture content.

- Normal construction with lightly reinforced strip footings and light reinforcement in masonry.

S2 >20 Stiffened strip footings, stiffened or cellular raft Deep strip foundations Compaction of in situ soils below individual footings Piled or pier foundations Soil raft

- Stiffened strip footing or stiffened or cellular raft with articulation joints or solid lightly reinforced masonry.

- Bearing pressure not to exceed 50kPa. - Fabric reinforcement in floor slabs. - Site drainage and service/plumbing precautions. - As for S1 but with fabric reinforcement in floor slabs - As for S1. - Reinforced concrete ground beams or solid slabs on piled or pier

foundations. - Ground slabs with fabric reinforcement. - Good site drainage. - As for S1.

NOTES: 1. Differential settlement assumed to equal 50% of total settlement 2. The relaxation of some of these requirements, e.g. the reduction or omission of steel or articulation joints, may

result in a Category 2 level of expected damage. 3. Account must be taken on sloping site since differential fill heights may lead to greater differential settlements. 4. Settlements induced by loads imposed by deep filling beneath surface beds may necessitate the adoption of a

construction type appropriate to a more severe site class.

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