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Operational Plan & Design Report HWSF Prepared by USK Consulting
1
PREPARED BY: USK Environmental & Waste Engineering Service Ground Floor
Fancourt Office Park, Block 4 Loft D
Ground Floor
Northerumberland Ave. North Riding 2169
South Africa Tel: +27 (0) 11 704 6433
Fax: +27 (086) 2703976 web: www.uskconsulting.com
PREPARED FOR: E-SQUARE ENGINEERING AND
TRANSNET ENGINEERING
GEOTECHNICAL INVESTIGATION REPORT FOR THE PROPOSED
TRANSNET ENGINEERING HAZARDOUS WASTE LANDFILL SITE AT
KOEDOESPOORT
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 2 of 37 Issue May 2015
DOCUMENT CONTROL SHEET
Client: E- SQUARE ENGINEERING
Report Title: GEOTECHNICAL INVESTIGATION REPORT FOR PROPOSED TRANSNET ENGINEERING
HAZARDOUS LANDFILL SITE AT KOEDOESPOORT
Report No: G15_002/01
Version: 1.0
Date Issued: MAY 2015
DOCUMENT DISTRIBUTION:
Copy Type Recipient Organization
1 PDF/Email Mr. Hamilton Sitole E- Square Engineering
2 Hard Copy Mr. Innocent Masunungure E- Square Engineering
Note: Electronic copies of this report are issued in portable document format and distributed via one of the following media; CD-ROM, Email or Internet Secure Server. Copies held by USK Consulting are stored on mass storage media archive. Further copies will be distributed on CD-ROM.
Prepared By Reviewed By Approved By
TECHNICAL
NAME Samuel Jjuko
NAME Dr. Denis Kalumba (MSAICE)
NAME Dr. Steve K Kalule (Pr.Sc.Nat)
SIGNATURE
SIGNATURE
SIGNATURE
DATE May 2015
DESIGNATION Geotechnical Engineer
DESIGNATION Geotechnical Engineer
DESIGNATION Director
USK Environmental & Waste Engineering Service Head Office
Ground Floor
Fancourt Office Park, North Riding, Johannesburg
Tel: +27 (0) 11 704 6433/ Fax: (086) 2703976
Eastern Cape Office
Tel: +27 (0) 43 748 5567/45
Fax: +27 (0) 43 748 1114 Email: [email protected]
Web: www.uskconsulting.com
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 3 of 37 Issue May 2015
DECLARATION OF INTEREST
This report has been professionally independently prepared by USK Environmental & Waste Engineering (Pty) Ltd, which is a South African Professional Consulting firm, with a team of professionals specializing in a number of environmental science and environmental engineering fields. Company Contact Details Head Office Physical Address: Loft C Block 4 Fancourt Office Park, North Riding, Johannesburg 2169 Telephone Number: (011) 704 6433 Fax Number: (086) 2703679 E-mail: [email protected]
DECLARATION INTEREST. I hereby declare that to the best of my knowledge USK Environmental & Waste Engineering (Pty) Ltd nor any of its members and consultants does not have any Interest in the project or associated projects. I undertake to inform the responsible representative of the client of any change in this information or any new information that needs to be reported, which occurs before or during the meeting or work itself and through the period up to the publication of the final report. Date: _________ Signature________________________________
Name Email Telephone
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 4 of 37 Issue May 2015
GEOTECHNICAL INVESTIGATION REPORT FOR PROPOSED TRANSNET
ENGINEERING HAZARDOUS LANDFILL SITE AT KOEDOESPOORT
Table of Contents
DOCUMENT CONTROL SHEET ..................................................................................................................... 2
DECLARATION OF INTEREST ...................................................................................................................... 3
1. INTRODUCTION ...................................................................................................................................... 6
1.1. Project Background ...................................................................................................................... 6 1.2. Scope of Work ............................................................................................................................. 6
2. SITE DESCRIPTION ................................................................................................................................ 7
2.1. Site Location ................................................................................................................................ 7
3. METHODOLOGY ..................................................................................................................................... 8
3.1. Field Work .................................................................................................................................... 8
4. ANALYSIS OF FIELD AND LABORATORY RESULTS ....................................................................... 11
4.1. General Site Description ............................................................................................................ 11 4.2. Site Geology .............................................................................................................................. 11 4.3. Site Hydrogeology ...................................................................................................................... 12 4.4. Description of the Soils .............................................................................................................. 12 4.5. Bedrock ...................................................................................................................................... 12 4.6. Bearing Capacity based on SPT – N Values ............................................................................. 13 4.7. Particle Size Analysis................................................................................................................. 13 4.8. Liquid Limit and Plastic Limit ..................................................................................................... 14 4.9. Compaction Characteristics ....................................................................................................... 15 4.10. California Bearing Ratio ............................................................................................................. 15 4.11. Excavation conditions ................................................................................................................ 15 4.12. Foundation Conditions ............................................................................................................... 16 4.13. Contamination Barrier and Cover .............................................................................................. 16
5. CONCLUSIONS AND RECOMMENDATIONS ..................................................................................... 17
REFERENCES ............................................................................................................................................... 19
APPENDICES ................................................................................................................................................ 20
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 5 of 37 Issue May 2015
Figures Figure 1 Locality Map of Study Site 7 Figure 2 Test Pit Excavations using TLB during the field investigation 10 Figure 3: 1:50 000 geological map of the Silverton area (2528 CB – Silverton) 12 Figure 4 Plasticity Chart 16
Tables
Table 1 GPS coordinates indicating the borehole positions ............................................................... 9 Table 2: Standard Test Methods ............................................................................................................ 10 Table 3: Log of BH01 ................................................................................................................................. 14 Table 4: Log of BH02 ................................................................................................................................. 14 Table 5: Log of BH03 ................................................................................................................................. 14
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 6 of 37 Issue May 2015
1. INTRODUCTION
1.1. Project Background
USK Environmental & Waste Engineering were appointed by E-Square Engineering (Pty) on
acting on behalf of Transnet Engineering, to undertake a geotechnical investigation for the
proposed Hazardous Waste Landfill Site at Koedoespoort, Pretoria. This geotechnical
investigation report is part of a suite of supporting documentation which is required as part of an
application for environmental authorization for the remediation of the contaminated sites at the
Koedoespoort, but also forms an important and integral part for the engineering design for the
proposed landfill site which is being planned to be the central tenet of the remedial approach
and plan.
1.2. Scope of Work
The main objectives of investigations comprised of the following:
To evaluate geo-technical parameters of the sub base soil at the site.
To conduct field investigations, tests pit excavations, in-situ testing, bulk soil sampling for
laboratory testing,
Laboratory testing on the redeemed bulk samples,
Review the geotechnical requirements for the development of foundations for the
proposed structures at the site,
Review the geotechnical requirements for the development of cells and associated
infrastructure for a landfill at the site,
Assess the requirements, and availability and suitability of cover material for the
operations of the landfill.
Assess the requirements, and availability and suitability of capping material for the
closure of the landfill.
Assess and evaluate the requirements, and risk issues for the landfill including, slope
stability, and permeability of soil.
Assess and evaluate the requirements for the landfill containment barrier system
(geomembrane lining) in accordance with the current legal framework and make key
recommendations in relation to the above site investigations.
Develop a suit of site-specific recommendations for consideration during the engineering
design of the proposed landfill site and associated infrastructure.
Compilation of a detailed report
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 7 of 37 Issue May 2015
2. SITE DESCRIPTION
2.1. Site Location
The Site is located on Portion 201 of Farm Hartebeespoort, situated in Silverton approximately
6.5 Km to the East of Pretoria Central Business District. Access to the site is off Trans Road,
which links to Dykor Road, connecting to Derdepoort Main Road in Silverton, Pretoria. (See
locality map in Figure 1).
Figure 1 Locality Map of Study Site
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 8 of 37 Issue May 2015
3. METHODOLOGY
3.1. Field Work
The field investigations for the site were conducted on 5th and 6th February 2015 in accordance
with South African Institution of Civil Engineering (SAICE) Site Investigation Code of Practice
2010. The key aspects of the investigation comprised of the following:
Identification of suitable test pit positions,
Pit excavations with a Caterpillar 428F 4x4 Tractor Loader & Backhoe (TLB),
Profiling of Test Pit excavations,
Borehole drilling by augering using the AMS 9500 VTR PowerProbeTM Environmental
and Geotechnical drill rig in accordance with method ASTM D6151-081,
Conducting standard penetration tests (SPT) in accordance with method ASTM D1586-112),
Recovery of bulk representative soils samples,
Description of soil properties,
The investigations consisted of:
Siting of seven (7) test pits and three (3) boreholes positions at strategic places for the
investigation program. The locations of the pits and boreholes based on GPS reading are
given in Table 1.
At the time of the investigation the landfill had been proposed to be in the centre of the site
with associated infrastructure, i.e., structures for the recycling plant, reverse logistics,
weigh bridge, etc. to be situated in the South, while the leachate dam was to be in the far
North East of the property. So the positions of the geotechnical test points were within the
respective footprints as shown in Figure 1.
Advancing boreholes by means of augering as deep as practicable using 108 mm hollow
stem augers. This auger method was used because the ground was stable and did not
have the tendency to collapse or cave into the borehole. So no casing was installed in
boreholes. The rig was equipped to perform standard penetration testing (SPT) using a
63.5 kg auto-drop hammer and 50 mm diameter split spoons. The depths investigated
ranged from 1.0 m to 3.6 m below ground level.
Excavation of trial pits by the TLB machine to a maximum depth of approximately 4.0 m or
to refusal when soft rock was encountered at shallow depth (Figure 2). Therefore, the
depth of exploration for test pits was greatly influenced by the nature of soils and rock in
the area.
1 Standard Practice for Using Hollow-Stem Augers for Geotechnical Exploration and Soil Sampling
2 Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils
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Soil profiling of 7 trial pits. Detailed soil profiles were drawn up from visual examination of
the in-situ material observed from the trial pits according to recommended standard
procedures. Individual soil profile descriptions are given in the in the Appendix.
Recovery of representative disturbed soil samples from trial pits at various depths and
placing them in dedicated labelled sample bags. These were sent to ROADLAB, 207
Rieffontein Road, Primrose Germiston, 1401, South Africa (Pty). The foundation indicators
and strength tests were then conducted according to standard test methods (Table 2). Full
results are presented in the appendix.
An assessment of field and laboratory results.
Geotechnical recommendations.
Table 1 GPS coordinates indicating the borehole positions
Bo
reh
ole
Nu
mb
er
ID GPS Location
Latitude Longitude
SB01 S 25o43’30.9” E 028
o17’14.3”
SB02 S 25 o
43’30.9” E 028o17’14.2”
SB03 S 25o43’33.9” E 028
o17’14.8”
Pit
nu
mb
er
TPI01 S 25o43’33.2” E 028
o17’16.9”
TP I02 S 25o43’28.4” E 028
o17’17.1”
TPI03 S 25o43’25.3” E 028
o17’20.3”
TPJ01 S 25o43’25.4” E 028
o17’20.2”
TPA/B01 S 25o43’33.7” E 028
o17’14.6”
TPH/Q01 S 25o43’33.2” E 028
o17’14.2”
TPF01 S 25o43’30.9” E 028
o17’14.3”
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 10 of 37 Issue May 2015
Figure 2 Test Pit Excavations using TLB during the field investigation
Table 2: Standard Test Methods
Name of Test Standard Test Method Sample Status
Grading/ Sieve Analysis TMH1 1986: A1 (a) Disturbed
Atterberg Limits TMH1 1986: METHOD A2 & A3; TMHA4 1974 Disturbed
California Bearing Ratio TMH1 1986: A7 & A8 Disturbed
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 11 of 37 Issue May 2015
4. ANALYSIS OF FIELD AND LABORATORY RESULTS
4.1. General Site Description
The property covers approximately 5 hectares most of which are covered with bushy grass and
shrubs. The entire property could be classified into three major zones: a) a rubble recycling
area in the North; b) concrete manufacturing plant in the Southeast and; c) an open
undeveloped land. The first two shall be of significance when developing the site. No access to
them had been granted at the time of study.
The open area, which consist of the bulk of the land, has been largely disturbed over several
years by previous activities related to grading, dozing and dumping of mixed waste including:
stock piles of concrete and other construction rubble, paint, tar, scrap metal, tyres, etc. There is
evidence of illegal dumping of material now mostly covered in over grown vegetation.
Environment significance of all this has to be considered during the development stage of the
land.
There is a drainage line that traverses through the site from the southwest towards the eastern
portion of the site. The eastern portion of the site is a low laying area and is characterized by
marshy, swampy and wetland like conditions. This marshy character could have been created
by the impounding of water from the surface water drainage over time, and/or as result of a
natural perched water table i.e. an is an accumulation of groundwater that is above the water
table in the unsaturated zone or marshland in the portion of the site.
No buried services were seen within site area. But it is expected that unidentified services could
be present and may be encountered during the performance of the excavation activities.
4.2. Site Geology
The site is underlain by shallow shale of the Silverton Formation on the South and the diabase
in the northern third of the site. Whilst the shale is relatively resistant to weathering and thus
the soil cover in the south is relatively thin, the diabase is resistant too and forms quite a
prominent ridge. The hard rock geology is covered by varying thicknesses of an overburden
that typically grades from mature residual soil through completely decomposed and weathered
rock to fresh bedrock. The evidence of the shale and diabase was intersected in all test pits
with the decomposed rock retaining the original rock structure. The 2528 CB Silverton 1:50 000
geological map confirms diabase intrusions underlying the study area.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 12 of 37 Issue May 2015
Figure 3: 1:50 000 geological map of the Silverton area (2528 CB – Silverton)
4.3. Site Hydrogeology
At the time of the investigation, there were no indications of presence of groundwater within the
top 4 m from the surface as no water table was encountered in all boreholes and trial pit
locations. However, there was seepage of water from sides of two trial pits TPA/B01 and
TPH/Q01 at 2.8 m and 3.2 m respectively. This was attributed to a possible localized patched
water table. As discussed previously, an open channel drainage line traverses eastwards
through the site to a marshy ground on the lowest areas of the property.
4.4. Description of the Soils
The site is characterized by the residual soils comprising clayey sand or sandy clay with pockets
of silty clay. The typical site soil profile may be described as:
0.0 - 0.2m Slightly moist, brown to dark brown, slightly stiff, silty with abundant organic
matter overlying
0.2 - 1.0m Moist, light/reddish brown to olive brown, stiff to very stiff, sandy clay overlying
1.0 - 2.0m Moist, light grey mottled orange in places, dense to very dense, clayey sand
(residual) overlying
2.0 - 4.5m Slightly moist to dry, light brown and grey, dense clayey sand/ very stiff sandy
clay, (residual shale/diabase).
Due to the weathering of the shale and diabase, variations to the above profile do occur across
the site. Generally, the soil profile tends to be more deeply weathered in the northern than in the
southern portions.
Koedoespoort site
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 13 of 37 Issue May 2015
The moisture content in the observed soil profile decreases with depth indicative of a relatively
deep regional water table.
4.5. Bedrock
The refusal in all boreholes and trial pits, except three trial pits (TPI01, TPI02 and TPI03), was
attributed to the shale formation in the south and diabase rock in the north. According to
borehole and trial pit logs, the depth to hard rock is therefore in excess of about 4.0 and 2.5 m in
the northern and southern portions respectively – with soft rock being probably between depths
of 2 m and 3 m. Tests were terminated between these depths
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 14 of 37 Issue May 2015
4.6. Bearing Capacity based on SPT – N Values
Based on the analysis of field SPT – N values, a safe bearing capacity of more than 300 kPa is
achieved at a depth of 600 mm from the ground surface at all three borehole locations. The
recorded logs in Tables 3, 4 and 5 show obtained SPT – N values. Detailed analysis is
presented in the appendices as Tables A2, A3 and A4.
Table 3: Log of BH01
Depth (m) Material Description SPT
Depth (m) N value (No. of blows)
0.0 – 0.4 Slightly moist, brown, slightly stiff, clayey silt with abundant organic matter (mixed with construction rubble/burnt bricks)
0.4 – 1.6 Slightly moist, yellow-brown, soft rock, highly weathered
1.00 – 1.45 35
1.6 – 3.6 Slightly moist, brown grey, medium hard rock, highly weathered
2.40 – 2.85 3.60 – 4.05
41 Refusal
Table 4: Log of BH02
Depth (m) Material Description SPT
Depth (m) N value (No. of blows)
0.0 – 0.4 Slightly moist, brown, slightly stiff, clayey silt with abundant organic matter
0.4 – 1.0 Slightly moist, red-brown, dense to very dense, clayey
1.00 – 1.45 Refusal
Table 5: Log of BH03
Depth (m) Material Description SPT
Depth (m) N value (No. of blows)
0.0 – 0.2 Slightly moist, brown, slightly stiff, clay silt with abundant organic matter
0.2 – 1.0 Slightly moist, red-brown, dense to very dense, clayey
1.00 – 1.45 31
1.0 – 2.0 Slightly moist to moist, yellow brown and grey, dense clayey sand/very stiff silty clay
2.00 – 2.45 Refusal
4.7. Particle Size Analysis
The main parameter of interest in understanding the behavior of soils is percentage of particles
passing the No. 200 sieve (75 µm sieve). Samples from trial pits TPI01 (0.3 – 2.2 m), TPI02 (0.5
– 4.0 m), TPA/B01 (0.0 – 1.2 m), TPH/Q01 (1.0 – 2.5 m), TPH/Q01 (2.5 – 3.2 m) and TPH/Q01
(0.2 – 1.0 m) exhibited a percentage passing the No. 200 sieve that was below 50%. This is
indicative of coarse-grained soils. Such soils are easy to compact, little affected by moisture,
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 15 of 37 Issue May 2015
less pervious and more stable. Samples from trial pits TPI03 (0.4 – 1.2 m), TPI04 (1.2 – 4.0 m),
TPJ01 (0.2 – 1.2 m), TPJ01 (1.2 – 2.2 m) and TPA/B01 (1.4 – 3.0 m) had a percentage passing
the No. 200 sieve that was above 50%. The high amounts of fines are indicative of presence of
clay and silt soil that is vulnerable to swelling and shrinkage with changes in water content. It is
also indicative of low permeability, which can result in deep excavations bottom heave when
such excavations are conducted in wet weather. If the floor basin is to be located on the shale
or diabase, this will not be an issue.
4.8. Liquid Limit and Plastic Limit
The liquid limit and plasticity index of obtained soil samples varied from 34.0 % to 59.0 % and
12.0 % to 26.0 % respectively. The linear shrinkage ranged between 6.1 % and 13.3 %. The
Linear Shrinkage values represent minimum percentage of water necessary to allow a soil to be
moulded. From figure 3 the soil layers were predominantly silts of intermediate to high plasticity
except TPA/B01 (0.0 – 1.2 m), TPH/Q01 (2.5 – 3.2 m) and TPH/Q01 (0.2 – 1.0 m) which were
clays of intermediate plasticity. Clays and silts of intermediate to high plasticity are associated
with medium to high expansion potential characteristics in presence of water hence cracking in
buildings and failure of foundations.
Soil layers from trial pits TPI01 (0.3 – 2.2 m), TPI02 (0.5 – 4.0 m), TPA/B01 (0.0 – 1.2 m) and
TPH/Q01 (1.0 – 2.5 m) had a grading modulus of greater than 2 indicative of good road building
quality material. The rest of the sampled soil layers had grading modulus of less than 2
indicative of poor road building quality material.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 16 of 37 Issue May 2015
Figure 4 Plasticity Chart
Samples from trial pits TPI01 (0.3 – 2.2 m), TPJ01 (0.2 – 1.2 m) and TPH/Q01 (1.0 – 2.5 m)
were classified as G7 materials according to TRH14. The rest of the samples were below the
quality of G10 material.
4.9. Compaction Characteristics
The maximum dry density (MDD) and optimum moisture content (OMC) values ranged between
1569 kg/m3 and 1996 kg/m3, and 11.6 % and 23.1 % respectively. Well-graded soils exhibit
higher MDDs than poorly graded soils while finer soils exhibit higher OMCs and lower MDDs
than coarser soils. Usually soils with MDD greater than 2000 kg/m3 and OMC less than 15%
are easier to compact and recommended for road construction. The MDD is also directly
proportional to the strength characteristics of a soil.
4.10. California Bearing Ratio
The California bearing ratio varied between 1.2 % and 33 % for the tested soil samples at 100 %
maximum dry density. Usually soils with CBR greater than 3 % are suitable for use as subgrade
materials in pavement construction. All soil layers classified, as below the quality of G10
materials would not be suitable for use in road construction. Therefore, only soil layers TPI01
(0.3 – 2.2 m), TPJ01 (0.2 – 1.2 m) and TPH/Q01 (1.0 – 2.5 m) would suitable.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 17 of 37 Issue May 2015
4.11. Excavation conditions
The boreholes were auger drilled to depths of 1,0 m to 3.6 m below the surface. The trial pits
were excavated with depths varying between 2.9 m and 4.0 m. The shale and diabase rocks
caused the drilling machine and TLB refusal at those respective depths. On this evidence the
use of a TLB could be utilized to excavate to a depth of about 1.4 m to 4.0 m below the surface.
(The observations regarding depth of excavation refer to depths measured from existing natural
ground level). Hard residual soils and rocks at deeper depth may result in difficult excavation
conditions. The use of a large excavator (18-20 ton) would probably be required to allow deeper
excavations in excess of 4.0 m over most of the site.
Due to the abundant fines content in the soil matrix material - includes silt and clay - within the
residual soils overlying the rock formations, saturation of the soils during extending raining
periods may result in difficulty working conditions. It is accordingly recommended that the bulk
earthworks be carried out with this in mind and preferably in the drier season.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 18 of 37 Issue May 2015
4.12. Foundation Conditions
The top approximately 0.4 m of the soils intersected in the boreholes and trial pits comprised
clayey silt / silty clay with abundant organic matter of variable composition. These soils are
considered to be nonstructural for supporting any imposed loading. Based on the detailed
examination of the SPT test results, the residual underlying the site from as little as 1.0 m below
existing ground level can be considered to be of sufficient strength for satisfactory support of
conventional spread footing foundations for the landfill associated infrastructure, dimensioned
not to exceed an average maximum permissible bearing pressure of 300 kPa. Differential
settlements should be minimal.
4.13. Contamination Barrier and Cover
Although the highly weathered to completely weathered residual soil in majority of the site can
be regarded as suitable construction material, much of the clayey or fine material found was
highly variable with considerable portions of silt, sand, etc. that were non plastic. Laboratory
results confirmed it to be of low to medium plasticity. Therefore, because of its quality and
contamination in several places (refer to previous USK Consulting reports of the site), it cannot
form an effective seal between the surface and the underlying rocks (and any associated
aquifer). Neither can it be suitable as one of the layers for the capping design.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 19 of 37 Issue May 2015
5. CONCLUSIONS AND RECOMMENDATIONS
Based on the field work undertaken and laboratory results obtained, no unstable geotechnical
conditions should prevent the development of this site into a landfill.
The following specific conclusions and recommendations are made:
The property is dominated by disturbed ground surface from previous activities related to
grading, dozing and dumping of mixed waste including: stock piles of concrete and other
construction rubble, paint, tar, scrap metal, tyres, etc. All of which have to be considered
before and during the development stage of the plot.
The in situ clayey or fine material was highly variable with considerable portions of silt,
sand, etc. that were non plastic. Laboratory results confirmed it to be of low plasticity.
Therefore, because of its quality and contamination in several places (refer to previous
reports submitted by USK Consulting), it cannot be suitable as one of the layers for the liner
or capping system.
Although ground water was not encountered in this investigation, the trickling water from
sides of two trial pits at depths between 2.8 m and 3.2 m is of concern. This indicates that
groundwater seepages during bulk deep excavation can however not be ruled out especially
during the wetter months.
Depending on the quantity of the waste to be landfilled, the proposed landfill cell basin floor
levels could be extended between 3.0 m and 4.0 m below the ground surface. Water
seepage at 2.8 in some regions may limit the levels in specific places to approximately 1.0
m above the localized water level. Additionally a subsurface drain channel would have to
be considered to protect the floor liner from becoming saturated from the seeping water.
This is especially relevant during the construction of the basin floor and lining system.
The rock sequence of shale and diabase has undergone weathering producing an
overburden grading from mature residual soil through completely decomposed and
weathered rock to fresh bedrock. The weathered residual material, composed of a matrix of
clayey sands and sandy clay soils, ranging from stiff to very stiff. This can suitably support
conventional spread footing foundations, for the landfill associated infrastructure,
dimensioned not to exceed an average maximum permissible bearing pressure of 300 kPa.
Differential settlements should be minimal.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 20 of 37 Issue May 2015
The in situ clayey sands and sandy clay soils are capable of forming the basin floor. It is
recommended that the preparation operation involves spreading, level and compacting to
98% standard proctor density.
Being generally cohesive or semi-cohesive, the ground did not have tendency to collapse
when disturbed. Excavation slopes of 45 in non-marshy areas could be sustained without
posing slope instability issues.
The excavation conditions between 1.0 m to 4.0 m below the ground surface will require a
TLB unless portions of outcrops of diabase and shale rocks are encountered. For deeper
layers, a 20 ton excavator should be capable of excavating with little difficulty.
Finally, it should be noted that an investigation of this nature is aimed at describing broad areas
in which problems may occur. It may be found that soil conditions at variance with those
discussed in this report do occur locally. The variant conditions should be inspected by
competent personnel to ensure that these conditions do not pose a problem for the development
of the proposed landfill site. More detailed testing in certain areas may be required in order to
produce the most suitable design with associated cost saving.
The USK consultants should be retained to review the final design plans and specifications so
comments can be made regarding interpretation and implementation of our geotechnical
recommendations in the design and specifications. They should also be retained to provide
observation and testing services during grading, excavation, foundation construction and other
earth-related construction phases of the project.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, express or implied, are intended or made. Site safety,
excavation support, and dewatering requirements are the responsibility of others. In the event
that changes in the nature, design, or location of the project as outlined in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless the consultants review the changes and either verify or modify the conclusions of
this report in writing.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 21 of 37 Issue May 2015
REFERENCES
1. BRINK, A.B.A. 1979, Engineering geology of Southern Africa. - Vol.1, Building Publications, Pretoria.
2. BRINK, A.B.A. 1982, PARTRIDGE, T.C. AND WILLIAMS, A.A.B., -Soil survey for engineering –
Monographs on Soil Survey, Oxford Press.
3. BRINK, A.B.A. 1983, Engineering geology of Southern Africa. - Vol.3, Building Publications, Pretoria.
4. BRYNE, G. AND BERRY, A.D. 2008, A guide to practical geotechnical engineering in Southern
Africa. –Franki, Fourth Edition.
5. JENNINGS, J.E. BRINK, A.B.A., AND WILLIAMS, A.A.B., 1973, Revised guide to soil profiling for
civil engineering purposes in South Africa. The Civil Engineer in S.A., Vol. 15 No. 1, January.
6. KRUGER, F.J., 2013, Short Geological Report on the Transnet Koedoespoort Site, GeoActiv (Pty)
Ltd
7. BURLAND, J.B., BURBIDGE, M.C. (1984), Settlement of foundations on sand and gravel,
Proceedings of the Institution of Civil Engineers, Part 1, 1985, 78, Dec., 1325-1381.
8. HATANAKA, M., UCHIDA, A. (1996). Empirical correlation between penetration resistance and
effective friction of sandy soil. Soils & Foundations, Vol. 36 (4), 1-9, Japanese Geotechnical Society.
9. MAYNE, P.W. (2001), Geotechnical site characterization using Cone, piezocone, SPTu, and VST,
Civil and Environmental Engineering Department, Georgia Institute of Technology
10. MEYERHOF, G.G. (1956), Penetration tests and bearing capacity of cohesionless soils, Journal of
the soil mechanics and foundation division, ASCE, Vol. 82, No. SM1, January, pp. 1-19.
11. SCHMERTMANN, J.H. (1975), Measurement of insitu shear strength, keynote lecture, Proceedings
of the conference on in-situ measurement of soil properties, June 1-4, 1975, vol. II, American Society
of Civil Engineers.
12. SAICE Site Investigation Code of Practice, 2010.
13. SANS3001 – AG21:2011: Determination of the bulk density, apparent density and water absorption
of aggregate particles passing the 5 mm sieve for road construction materials.
14. TMH1: Method A2: The determination of the liquid limit of soils by means of the flow curve method.
15. TMH1: Method A3: The determination of the plastic limit and plasticity index of soils.
16. TMH1: Method A4: The determination of the linear shrinkage of soils.
17. TMH1: Method A5: The determination of the percentage of material, in a soil sample, passing a 0,075
mm sieve.
18. TMH1: Methods A1: The wet preparation and sieve analysis of gravel, sand and soil samples.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 22 of 37 Issue May 2015
APPENDICES
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 23 of 37 Issue May 2015
Table A.1 Laboratory testing regime
Trial Pit Sample Depth(m) Indicator
Tests
Compaction
(Proctor)
Test
Unconfined
Compressive
Strength
California
Bearing Ratio
TPI01 0.3 – 2.2 x x x x
TPI02 0.5 – 4.0 x x x x
TPI03 0.4 – 1.2 x x x x
TPI04 1.2 – 4.0 x x x x
TPJ01 0.2 – 1.2 x x x x
TPJ01 1.2 – 2.2 x x x x
TPA/B01 0.0 – 1.2 x x x x
TPA/B01 1.4 – 3.0 x x x x
TPH/Q01 1.0 – 2.5 x x x x
TPH/Q01 2.5 – 3.2 x x x x
TPH/Q07 0.2 – 1.0 x x x x
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 24 of 37 Issue May 2015
Table A.2: Bearing Capacity Calculations from SPT – N values Analysis for BH1
Input values
N (average value between depth between D and
D+B) 19.75
ER 60
SPT Correction factors
Cs 1
Cr 1
Cb 1
Ce 1
N60 19.75
Design parameters
D/B 0.5
Effective unit weight (kN/m^3) 9.23
Foundation Width (m) 0.6 1 1.5 2 2.5
Depth of interest (m) 0.6 1 1.5 2 2.5
Vertical effective stress (kPa) 5.538 9.23 13.845 18.46 23.075
Liao & Witman depth correction factor 0.2353 0.3038 0.3721 0.4297 0.4804
N1,60 39.50 39.50 39.50 39.50 39.50
TERZAGHI BEARING CAPACITY EQUATION FOR SANDS
Applied Factor of Safety 3.00
Using Hatanaka & Uchida (1996), Mayne (2001) equation
Friction angle (degrees) 44.7 44.7 44.7 44.7 44.7
Ngamma (Chen) 349.8 349.8 349.8 349.8 349.8
Ngamma (Brinch-Hansen) 188.1 188.1 188.1 188.1 188.1
Nq (same for all) 127.9 127.9 127.9 127.9 127.9
Ultimate capacity (kPa) 875.0 1458.3 2187.4 2916.6 3645.7
Allowable stress (kPa) 291.7 486.1 729.1 972.2 1215.2
Using De Mello (1971), Schmertmann (1975) and Mayne (2001) equation
Friction angle (degrees) 48.8 48.3 47.7 47.1 46.5
Ngamma (Chen) (not used) 835.5 743.8 649.9 573.5 510.6
Ngamma (Brinch-Hansen) 439.2 392.2 344.0 304.6 272.0
Nq (same for all) 257.1 234.0 209.9 189.8 172.9
Ultimate capacity (kPa) 1928.1 2890.2 3833.9 4562.9 5132.7
Allowable stress (kPa) 642.7 963.4 1278.0 1521.0 1710.9
DEFORMATION CRITERION
Using Burland & Burbridge (1984) Approach
Allowable settlement (mm) 25.4
Inducing mean-σ stress KPa 761.9 532.9 401.2 328.0 280.6
Inducing mean stress (kPa) 1386.5 969.7 730.1 596.9 510.6 )nducing mean+σ stress KPa 2523.0 1764.5 1328.5 1086.2 929.1
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 25 of 37 Issue May 2015
Table A.3: Bearing Capacity Calculations from SPT – N values Analysis for BH2
Input values
N (average value between depth between D and
D+B) 21
ER 60
SPT Correction factors
Cs 1
Cr 1
Cb 1
Ce 1
N60 21
Design parameters
D/B 0.5
Effective unit weight (kN/m^3) 9.23
Foundation Width (m) 0.6 1 1.5 2 2.5
Depth of interest (m) 0.6 1 1.5 2 2.5
Vertical effective stress (kPa) 5.538 9.23 13.845 18.46 23.075
Liao & Witman depth correction factor 0.2353 0.3038 0.3721 0.4297 0.4804
N1,60 42.00 42.00 42.00 42.00 42.00
TERZAGHI BEARING CAPACITY EQUATION FOR SANDS
Applied Factor of Safety 3.00
Using Hatanaka & Uchida (1996), Mayne (2001) equation
Friction angle (degrees) 45.4 45.4 45.4 45.4 45.4
Ngamma (Chen) 408.0 408.0 408.0 408.0 408.0
Ngamma (Brinch-Hansen) 218.6 218.6 218.6 218.6 218.6
Nq (same for all) 144.5 144.5 144.5 144.5 144.5
Ultimate capacity (kPa) 1005.5 1675.8 2513.6 3351.5 4189.4
Allowable stress (kPa) 335.2 558.6 837.9 1117.2 1396.5
Using De Mello (1971), Schmertmann (1975) and Mayne (2001) equation
Friction angle (degrees) 49.4 48.9 48.3 47.7 47.1
Ngamma (Chen) (not used) 953.5 847.5 739.0 651.0 578.6
Ngamma (Brinch-Hansen) 499.4 445.3 389.8 344.5 307.2
Nq (same for all) 286.2 260.1 232.8 210.2 191.1
Ultimate capacity (kPa) 2175.6 3255.5 4309.8 5119.8 5749.3
Allowable stress (kPa) 725.2 1085.2 1436.6 1706.6 1916.4
DEFORMATION CRITERION
Using Burland & Burbridge (1984) Approach
Allowable settlement (mm) 25.4
Inducing mean-σ stress KPa 830.3 580.7 437.2 357.5 305.8
Inducing mean stress (kPa) 1510.9 1056.7 795.6 650.5 556.4 )nducing mean+σ stress KPa 2749.4 1922.8 1447.7 1183.6 1012.5
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 26 of 37 Issue May 2015
Table A.4: Bearing Capacity Calculations from SPT – N values Analysis for BH3
Input values
N (average value between depth between D and
D+B) 21.25
ER 60
SPT Correction factors
Cs 1
Cr 1
Cb 1
Ce 1
N60 21.25
Design parameters
D/B 0.5
Effective unit weight (kN/m^3) 9.23
Foundation Width (m) 0.6 1 1.5 2 2.5
Depth of interest (m) 0.6 1 1.5 2 2.5
Vertical effective stress (kPa) 5.538 9.23 13.845 18.46 23.075
Liao & Witman depth correction factor 0.2353 0.3038 0.3721 0.4297 0.4804
N1,60 42.50 42.50 42.50 42.50 42.50
TERZAGHI BEARING CAPACITY EQUATION FOR SANDS
Applied Factor of Safety 3.00
Using Hatanaka & Uchida (1996), Mayne (2001) equation
Friction angle (degrees) 45.6 45.6 45.6 45.6 45.6
Ngamma (Chen) 420.7 420.7 420.7 420.7 420.7
Ngamma (Brinch-Hansen) 225.2 225.2 225.2 225.2 225.2
Nq (same for all) 148.1 148.1 148.1 148.1 148.1
Ultimate capacity (kPa) 1033.6 1722.7 2584.1 3445.5 4306.8
Allowable stress (kPa) 344.5 574.2 861.4 1148.5 1435.6
Using De Mello (1971), Schmertmann (1975) and Mayne (2001) equation
Friction angle (degrees) 49.5 49.0 48.4 47.8 47.2
Ngamma (Chen) (not used) 978.4 869.3 757.7 667.3 592.9
Ngamma (Brinch-Hansen) 512.1 456.4 399.4 352.9 314.5
Nq (same for all) 292.3 265.5 237.6 214.4 194.9
Ultimate capacity (kPa) 2227.3 3331.9 4409.1 5235.9 5877.7
Allowable stress (kPa) 742.4 1110.6 1469.7 1745.3 1959.2
DEFORMATION CRITERION
Using Burland & Burbridge (1984) Approach
Allowable settlement (mm) 25.4
Inducing mean-σ stress KPa 844.2 590.4 444.5 363.4 310.9
Inducing mean stress (kPa) 1536.1 1074.3 808.9 661.3 565.7 )nducing mean+σ stress KPa 2795.3 1955.0 1471.9 1203.4 1029.4
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 27 of 37 Issue May 2015
Table A.5: Trial Pit TPI01 Soil Profile
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Table A.6: Trial Pit TPI02 Soil Profile
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 29 of 37 Issue May 2015
Table A.7: Trial Pit TPI03 Soil Profile
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Table A.8: Trial Pit TPJ01 Soil Profile
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Table A.9: Trial Pit TPA/B01 Soil Profile
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 32 of 37 Issue May 2015
Table A.10: Trial Pit TPH/Q01 Soil Profile
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 33 of 37 Issue May 2015
Table A.11: Trial Pit TPF01 Soil Profile
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Table A.12: Laboratory Test Results
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Table A.13: Laboratory Test Results cont.
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Table A.14: Laboratory Test Results cont.
Geotechnical Investigation Report G15_002/1/ Transnet Engineering – Koedoespoort Page 37 of 37 Issue May 2015