• Postal Address: Postnet Suite 457, Private Bag x29, Gallo Manor, 2052
• Physical Address: 44 Andries Street, Wynberg, Sandton, 2019
• Tel: +27 0861 GEOSURE (436 7873) • Fax: 086 689 5506 • Mobile: +27 (0) 82 784 0544
• E-Mail: [email protected]
www.geosure.co.za
LEVEL 1 BEE CONTRIBUTOR
Report to Malani Padayachee & Associates (Pty) Ltd on the
Results of a Deeper Geotechnical Investigation for the
Proposed Tower Structure for the Central Fire station,
Johannesburg, Gauteng
Geotechnical Engineering Services
Engineering Geology
Environmental and Groundwater
Pile Integrity Testing
SANAS Accredited Soil & Rock Laboratory
Earthworks/Materials Supervision & Control
Geotechnical Monitoring Systems
Road Pavement Materials and Design
Project Management
Reference: JHB015-19.R01
Revision 0
Dated: 27 June 2019
Geosure Gauteng (Pty) Ltd www.geosure.co.za JHB015-19.R01.docx
Report to Malani Padayachee & Associates (Pty) Ltd
on the Results of a Deeper Geotechnical
Investigation for the Proposed Tower Structure for
the Central Fire station, Johannesburg, Gauteng
Reference : JHB015-19.R01
Revision 0
Dated : 27 June 2019
GEOSURE (PTY) LTD Geotechnical, Environmental & Groundwater Engineering Consultants
SANAS Accredited Soil and Rock Laboratory
Head Office & Laboratory
122 Intersite Avenue, Umgeni Business Park, Durban, 4001, South Africa
PO Box 1461, Westville, 3630
Head Office
Tel.: 031 266 0458 (International +2731 266 0458)
Fax: 086 689 5506 (International +2786 689 5506)
Cell: +27 (0)82 784 0544
E-mail: [email protected]
Civil Engineering Laboratory Gauteng Branch
Tel: 031 701 9732 Postnet Suite 457, Private Bag X29,
Gallo Manor, 2052
Fax: 086 684 9785 Tel: 0861 GEOSURE (4367873)
Cell: 072 870 2621 Cell: +27 (0)82 557 0473
E-mail: [email protected] Fax: +27 086 689 8327
E-mail: [email protected]
www.geosure.co.za
Geosure Gauteng (Pty) Ltd www.geosure.co.za JHB015-19.R01.docx
Document Control Record
Document prepared by:
Geosure Gauteng (Pty) Ltd
44 Andries Street
Wynberg
Sandton
2019
Tel: 0861 436 7873
Fax: 086 689 5506
E-mail: [email protected]
Website: www.geosure.co.za
A person using Geosure Gauteng (Pty) Ltd documents must take note of the following:
a) Electronic copies to be checked against original hard copy version to ensure accuracy.
b) Using the documents or data for any purpose not agreed to in writing with Geosure
(Pty) Ltd is prohibited.
Document Control
Report Title Report to Malani Padayachee & Associates (Pty) Ltd on the Results of a
Deeper Geotechnical Investigation for the Proposed Tower Structure for
the Central Fire station, Johannesburg, Gauteng
Report Reference JHB015-19.R01 Responsible Person Mr D. Gertzen
Client Name Johannesburg
Development Agency
Client Contact Details
Revision Date Revision Details/Status Author Reviewer
0 20/02/2018 Geotechnical report with
recommendations Mr N. Govender Mr F. Smith
Current Revision 0
Approval
Author Signature
Reviewer Signature
Name Nishen Govender
Pr. Sci. Nat Name
Francis Smith
Pr. Sci. Nat
Title Technical Manager Title Associate
Geosure Gauteng (Pty) Ltd www.geosure.co.za JHB015-19.R01.docx
Abbreviations and definitions
Abbreviation Definition
AASHTO American Association of State Highway and Transportation
CBR California Bearing Ratio
E East
EGL existing ground level
Geosure Geosure Gauteng (Pty) Ltd
GM grading modulus
IMC insitu moisture content
JDA Johannesburg Development Agency
JMPD Johannesburg Metropolitan Police Department
kN/m2 kilonewtons per metre square
LL liquid limit
LS linear shrinkage
m metre (s)
MDD maximum dry density
mm millimetre
MPA Malani Padayachee & Associates
No. number
N North
OMC optimum moisture content
PI plasticity index
SANS South African National Standards
S South
TLB Tractor Loader Backhoe
TRH Technical Recommendations for Highways (1985)
Geosure Gauteng (Pty) Ltd www.geosure.co.za JHB015-19.R01.docx
Report to Malani Padayachee & Associates (Pty) Ltd on the
Results of a Deeper Geotechnical Investigation for the Proposed
Tower Structure for the Central Fire station, Johannesburg,
Gauteng
Reference: JHB015-19.R01 Revision 1 Date: 27 June 2019
TABLE OF CONTENTS
1. INTRODUCTION AND TERMS OF REFERENCE .......................................................................... 6
2. SCOPE OF REPORT .............................................................................................................................. 6
3. GUIDELINES FOR METHODOLOGY OF INVESTIGATION ....................................................... 6
4. INFORMATION USED .......................................................................................................................... 7
5. SITE DESCRIPTION ............................................................................................................................. 7
6. FIELDWORK .......................................................................................................................................... 9
6.1 GEOTECHNICAL BOREHOLE ............................................................................................................................. 9
7. INFERRED GEOLOGY AND ANTICIPATED SUBSURFACE CONDITIONS ...........................10
8. GROUNDWATER .................................................................................................................................12
9. DISCUSSION ..........................................................................................................................................12
9.1 PROPOSED DEVELOPMENT ..............................................................................................................................12 9.2 MINING ACTIVITY BENEATH THE SITE ...........................................................................................................12 9.3 GLOBAL STABILITY ........................................................................................................................................14 9.4 TRENCHABILITY ASSESSMENT ........................................................................................................................14 9.5 EARTHWORKS .................................................................................................................................................14 9.6 FOUNDING CONDITIONS ..................................................................................................................................16 9.7 FOUNDATION RECOMMENDATIONS FOR THE PROPOSED FIRE STATION ..........................................................16
9.7.1 Pad/Strip Footings on Rock .....................................................................................................................16 9.7.2 Piled Foundation .....................................................................................................................................16 9.8 DRAINAGE ......................................................................................................................................................18
10. SUMMARY AND OBSERVATIONS ...................................................................................................18
11. REFERENCES .......................................................................................................................................18
Appendix A: Borehole Profile
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Report to Malani Padayachee & Associates (Pty) Ltd on the Results of a
Deeper Geotechnical Investigation for the Proposed Tower Structure for
the Central Fire station, Johannesburg, Gauteng
Reference: JHB015-19.R01 Revision 0 Date: 27 June 2019
1. INTRODUCTION AND TERMS OF REFERENCE
Geosure was appointed by Johannesburg Development Agency (Pty) Ltd (JDA) in
January 2018 to carry out a geotechnical investigation for the construction of the New
Central Fire Station. A shallow geotechnical investigation was carried out which entailed
inspection pits being excavated by hand to a maximum depth of 1.5m below existing
ground level (EGL). A recommendation given in the shallow geotechnical report was to
drill an additional borehole at the proposed elevated tower site to confirm rock levels for
the proposed foundations. The report arising from the above investigation is dated 31st July
2018 and titled “Report to Johannesburg Development Agency (Pty) Ltd on the Results of
a Shallow Geotechnical Investigation for the Proposed Central Fire station,
Johannesburg, Gauteng” and reference 015-18.R01. Revision 1.
In May 2019, JDA requested Geosure to provide a cost estimate to carry out the
supplementary investigation. Geosure issued a proposal and cost estimate under cover of a
letter referenced p339-19 (Central fire Station)/ng and dated 21 May 2019.
Subsequently, Geosure was authorised by Malani Padayachee & Associates (Pty) Ltd
(MPA), hereafter referred to as “the Client”, in a letter of appointment dated 30 May 2019
to proceed with the investigation as proposed.
2. SCOPE OF REPORT
This report details the results of a deeper geotechnical investigation for the proposed tower
structure for the New Central Fire Station in Johannesburg, Gauteng.
The slope and subsurface conditions at the positions profiled on the site are described and
comment is made on the general stability of the site. Recommendations for earthworks,
drainage, materials excavatability, foundations, and comment regarding any mining
activity beneath the site, are made.
3. GUIDELINES FOR METHODOLOGY OF INVESTIGATION
The fieldwork for the investigation was carried out according to guidelines relevant to
geotechnical investigations of this nature.
The formation and weathering of geological materials are discontinuous processes and
unexpected variations in soil, rock and groundwater regimes may occur even on sites
where the conditions seem to be uniform or consistent. Variations in what is reported here
may become evident during construction and it is thus imperative that an appropriately
qualified and experienced Competent Person inspects all critical stages of development
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including, but not limited to, excavations to assess the conditions encountered and to assist
in the interpretation of observations at variance with the information supplied in this report.
This report was prepared for use by MPA and their professional team for the purpose
stated and should not be relied upon for any other purpose.
4. INFORMATION USED
The following information was referenced to assist with the fieldwork and preparation of
this report in the investigation:
i. A digital copy of a survey drawing no. AAM/12814A/01, titled “Topographic
Survey of Proposed Central Johannesburg Fire Station”, dated 02 August 2017
and prepared by Geomatics to a scale of 1:500;
ii. A 1:250 000 Regional Geological Map titled “2628 Eastrand”, dated 1986 and
published by the Council for Geoscience of South Africa;
iii. Digital copy of a underground mine survey drawing, titled “Underground Mine
Plan”, prepared by Village Main Reef G.M. Co. (1934) Ltd to a scale of 1:2000.
(Information supplied by JDA).
iv. Low resolution aerial imagery sourced from Google Earth (2018).
5. SITE DESCRIPTION
The site is located within the Johannesburg Central Business District at approximate
latitude and longitude 26.209913° S and 28.043734° E, respectively. Existing development
comprises an impound parking area which is managed by Johannesburg Metropolitan
Police Department (JMPD).
Two structures were observed on site, namely, a newly developed office block and a guard
house.
Significant rutting was observed along the parking areas with many areas being water
logged from recent rainfall activity. Palisade fencing surrounds the site with the JMPD
grounds forming the southern boundary and office blocks forming the northern and eastern
boundaries.
Topographically, the site is relatively flat to gently sloping towards the north, after a
significant infilling exercise to raise ground levels to their present levels.
Plate 1 overleaf provides an indication of the site locality whilst Plates 2 and 3 overleaf
provide a general view of the site.
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Plate 1: Locality Plan (sourced from Google Earth)
Plate 2: View of the site from the south showing the water logged areas on site
N
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Plate 3: View of the site from the west
6. FIELDWORK
The fieldwork for the investigation was carried out over the period 10 June 2019 to
14 June 2019 and comprised the drilling of a single borehole.
6.1 Geotechnical Borehole
A single geotechnical borehole, designated BH1 was carried out by Roelf Fourie
Geotechnical Services at the approximate positions given in Plate 4. The borehole was
advanced through the subsurface using an NWD4 core barrel to a final depth of 10.5m
below EGL.
The latitude and longitude coordinates as well as the approximate elevations and
approximate final depths of the borehole is given in Table 1 below.
Table 1: Latitude and Longitude Coordinates, Approximate Elevation and Final
Depths of borehole
BH No. Latitude Longitude
*Approximate
Elevation
above MSL (m)
Final Depth
below EGL
(m)
Final
Elevation
above MSL
(m)
BH1 26.21044 S 28.04347 1745 10.5 1734.5
*- Elevations measured using a hand held GPS device
The borehole was profiled using the South African Geoterminology Guidelines (Brink &
Bruin, 2002). Copies of the detailed borehole profiles are given in Appendix A.
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Plate 4: Location of the borehole drilled on site
7. INFERRED GEOLOGY AND ANTICIPATED SUBSURFACE
CONDITIONS
According to the 1:250 000 regional geological map of East Rand referenced “2628
Eastrand”, the general area of the site is underlain by quartzite and conglomerate of
Central Rand Group (Rjo). An extract of the above geological map is included below as
Plate 5.
Plate 5: Extract of Regional Geological Map of the Site (“2628 Eastrand”, by the Council for
Geoscience)
!(Proposed Firestation Site
GISCOE
N
Key:
Pv – Vryheid Formation sandstone Msy – Mokolian age syenite
Ra – Feldspary porphyry of Klipriviers Group
Rj – Shale, quartzite, conglomerate of West Rand Group
Rjo - Quarzite, conglomerate of Central Rand Group
Gold Mine
Gold Mine
N
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The following soil horizons in order of increasing depth have been observed in the
inspection pits excavated on site:
i. Unit 1: Fill Layer 1 - The fill layer can be described generally as dark grey, dense,
coarse, GRAVEL. This fill layer generally extended to an approximate depth of 0.5m
below EGL.
ii. Unit 2: Fill Layer 2 - The fill layer can be described generally as Pale brown to dark
grey, soft, fine grained, sandy SILT. This fill layer generally extended below the fill
of Unit 1 to an approximate depth of 1.0m below EGL.
iii. Unit 3: Residual Sandstone - The fill layer can be described generally as reddish
orange, medium dense, medium to coarse grained, sandy GRAVEL with rock
fragments. The residual layer generally extended to rock level at an approximate
depth of 1.95m below EGL.
iv. Unit 4: Weathered Quartzitic Sandstone Rock - The weathered rock can be
described as pale pink to cream with yellowish orange stains along joints, completely
weathered, medium to coarse grained, highly fractured, very soft rock from a depth
of approximately 3.0m below EGL. Between a depth of 3.0m and 8.2m below EGL,
it becomes a highly weathered, highly fractured, soft to medium hard rock with
coarse quartzitic inclusions, and a medium hard rock from 8.2m to the final depth
drilled of 10.0m below EGL.
Plate 6 below provides a visual of the borehole core extracted from the site
Plate 6: Borehole core extracted from the borehole
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8. GROUNDWATER
A standpipe piezometer was installed in the borehole to measure the depth of the
groundwater. The approximate depth to the groundwater level was measured on
14 June 2019 and is given in Table 2.
Table 2: Approximate Depth to Groundwater Levels
BH No. Approximate Depth to Groundwater Levels BH1 5.40m
Seasonal fluctuations in shallow groundwater levels related to rainfall patterns are,
therefore, likely intermittently during the traditionally “wet” season and/or after periods of
sustained rainfall.
The necessity for implementation of subsurface drainage measures or suitable foundation
controls should be assessed during the construction phase of the project in consultation
with the geotechnical professional.
9. DISCUSSION
9.1 Proposed Development
Information received by Geosure indicates that tower structure is proposed for the site.
Information supplied by the Engineers indicate that the tower will be approximately 18m
in height and have an approximate foundation load of 150 kN/m2 respectively. No further
structural details of the proposed building structure was made available to Geosure at the
time of preparation of this report.
Geosure will need to be given the opportunity to review the recommendations in this report
once detailed information regarding the design and layout of the proposed development is
available.
9.2 Mining Activity Beneath The Site
The geological map (refer to Section 7, Plate 5) indicates at least three gold mines within
close proximity of the site.
Referring to a drawing from the Department of Mine Surveys in Pretoria, confirmed that
the site is undermined from depths between approximately 46m to 244m below EGL.
Plate 7 below is an extract of the Department of Mines building restrictions from 1970.
Plate 8 overleaf (red boundary) is an extract of the underground mine plan for the site.
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Plate 7: Department of Mines Building Restrictions
Plate 8: Extract of Underground Mine Layout
Referring to the above building restrictions (Plate 7 refers), no building should be
constructed in an area in which mining activities occur or occurred within a depth of
91m below EGL.
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Taking the above restrictions into account and considering the numerous building activities
located within 100m of the site, it is advised that permission be obtained from the
Department of Mineral Resources for the proposed development on the site.
9.3 Global Stability
On the basis of our observations, the site is considered stable from a geotechnical
perspective in its current condition investigated and suitable for the development a
proposed provided the recommendations set down below in this report are adopted and
certified by Geosure. Measures amount to no more than sound development practices
appropriate to the site conditions anticipated and nature of the architectural scheme known
to Geosure at the time of preparation of this report.
9.4 Trenchability Assessment
“Soft” excavation in terms of SANS 1200 is generally anticipated within the soil cover (fill
and residual sandstone) and very soft sandstone rock.
The soft to medium hard quartzitic sandstone rock are likely to classify as “Intermediate”
to “Hard” material excavation in terms of SANS 1200.
The hard sandstone rock is likely to classify as “Hard” material excavation in terms of
SANS 1200.
Nonetheless, limited “Intermediate” and “Boulder” excavations to the depths investigated
cannot be discounted and it is recommended that a contingency amount be allowed for
“Intermediate” and “Boulder” excavations at shallower depths due to likely geological
variations.
Slow excavation rates beneath the water table are considered likely. Dewatering of
excavations is considered likely.
9.5 Earthworks
It is recommended that all earthworks be carried out in accordance with SANS 1200
(current version). All vegetation, topsoil and unsuitable subgrade material should be
cleared from areas over which fills are to be built. Under fills of more than three metres in
height, further subgrade improvement may be necessary.
9.5.1 General Fills
Fill slopes should be formed to not exceed a batter of 1 vertical to 2 horizontal (≤ 26°) and
a height of 1.5m where retaining systems are not provided. Slopes exceeding 1.5m in
height will need to be designed and inspected by a competent geotechnical practitioner to
ensure long term stability.
General fills should be placed in layers not exceeding 0.25m when placed in loose
condition, and compacted to a minimum of 93% of Modified AASHTO maximum dry
density within 1 – 2 percent (wet / dry) of Optimum Moisture Content (OMC). Boulder’s
larger than 0.2m in size should not be included in the fill material. Large boulders or
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builder’s rubble within the fill could affect compaction and mask voids into which fines
could later migrate, resulting in subsidence. Boulders / rubble may also adversely affect
foundation excavations.
Density control testing of fill material should be undertaken at appropriate intervals during
fill construction.
The sandy materials on site are considered highly erodible and sloughable due to
uncontrolled surface water runoff and special consideration will need to be given to
prevent erosion by uncontrolled stormwater runoff both during and after construction.
Platforms should also be shaped to direct water away from the fill embankments and
buildings. The use of earth bunds along the edge of fill embankments is recommended to
prevent water from overtopping and eroding fill embankments.
All banks should be grassed as soon as possible, preferably commencing during
construction.
9.5.2 General Cuts
Cuts in insitu soils may be formed to not exceed a batter of 1 vertical to 2 horizontal
(≤ 26°) and a height of not more than 1.5m where retaining systems are not provided.
Slopes exceeding 1.5m in height will need to be designed and inspected by a geotechnical
professional to ensure long term stability.
Cuts in weathered rock may be formed to batters of 1 vertical to 0.75 horizontal and to a
height not greater than 3.0m where retaining walls are not provided. Where daylighting
bedding planes are encountered during construction, it is recommended that a geotechnical
specialist be appointed to inspect the cutting and assess the global stability of the slope.
Cut and fill heights greater than 2.0m would need to be inspected and approved by a
geotechnical professional.
Sidewall collapse of excavations not battered back or shored is considered likely. The
construction and selection of appropriate retaining structures to engineer’s detail will be
critical as temporary vertical / oversteep slopes are likely to be unstable.
Where excavations intersect or approach the water table, the sidewalls will tend to become
unstable and need to be drained and laterally supported or battered back at slopes of the
order of 1 vertical in 5 horizontal. Suitable permanent dewatering by a specialist are
recommended to achieve a dry stable and safe working environment for the construction of
the proposed basement.
Workers should not enter any excavations deeper than 1.5m that are not shored or battered
back. Steeper batters can be considered but will be subject to inspection and approval by a
geotechnical professional on site during construction. It remains, however, the
responsibility of the contractor/engineer on site to ensure excavations are safe and shored
in line with requirements as set down in the current “Occupational Health and Safety” Act
85 (1993 as amended).
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9.6 Founding Conditions
The fill layer is considered to be unsuitable as a founding layer for the tower structure and
the use of shallow concrete foundations. Based on the borehole investigation founding
depths greater 3m below EGL is considered to be suitable founding media.
9.7 Foundation Recommendations for the Proposed Fire Station
Information supplied to Geosure indicates that an approximate foundation load of
150kN/m2 is proposed for the site.
Accordingly, taking into account the likely proposed development and inferred founding
conditions, it is recommended that the following foundation types be considered:
i. Pad/spread footings placed on soft to medium hard rock; and
ii. Piled foundations.
9.7.1 Pad/Strip Footings on Rock
It is recommended that all foundations for the proposed structure be taken down through
the fill and residual material and placed on the weathered sandstone rock where a
maximum net allowable bearing pressure of 200kN/m2 is considered applicable. Soft
sandstone rock was encountered from a depth of approximately 2.0m below EGL.
Total settlement is likely to be in the range less than 5mm with approximate differential
settlement taken as 50% of the total settlement.
Any loose or remoulded material must be removed from foundation trenches prior to the
casting of concrete. All footings and brickwork will need to be reinforced as determined
by a structural engineer. All foundation excavations must be inspected and approved by
Geosure to confirm bearing pressures.
9.7.2 Piled Foundation
Should there be a concern with the structural engineer with regards to upliftment of the
structure due to external forces on the proposed structure, it is considered that the foundation
loads be supported on a piled foundation socketed adequately into rock.
Consideration should be given to the use of the following piled foundation systems:
i) Continuous Flight Auger (CFA) piles; and/or
ii) Driven Cast Insitu (DCI) piles.
Other pile types may be considered if there is adequate assurance that the installation
equipment and procedures can:
i) ensure that the piles will be advanced to the required founding depth;
ii) prove the structural integrity of the pile shafts; and
iii) ensure the absence of disturbed material below the pile base.
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Typical working loads for various pile diameters are given in Table 3 as a guideline for
budgetary purposes only.
Table 3: Central Fire Station Tower Structure: Guidelines for Typical Pile Diameter
and Allowable Working Loads
Pile Type Pile diameter
(mm)
Typical Working Load
(kN)
CFA
250 250
300 350
350 450
DCI 355 500
410 750
Pile lengths will be dependent on the final platform level and the detailed pile design must
be provided by the piling contractor. For budgeting purposes, pile lengths are anticipated to
be between 5m to 6m in length considering that the piles will be socketed into soft to
medium hard rock by at least 2m to 3m.
The determination of the required diameter, depth and reinforcing of the piles will also be
influenced by factors such as configuration and spacing of the piles in groups beneath the
pile caps, depth of the bottom of the pile cap below ground level and factors of safety or
partial factors in accordance with the design code adopted by the structural engineer.
The levels of the pile caps should be designed as shallow as possible to limit requirements
associated with temporary dewatering of any wet excavations.
Final pile founding levels will need to be reviewed by the pile designer by observing the
piles formed in the field.
It is recommended that static load capacity tests be carried out on selected piles in order to
confirm the pile working loads and pile design. The static load capacity tests should be
carried out prior to the commencement of the piling contract. Geosure’s appointment
should be extended to review the results of such static load capacity tests.
Axial settlement of single isolated piles, excluding settlement that occurs during
construction of the superstructure, should not exceed elastic shortening of the pile shaft
plus 10mm. Additional settlement due to grouping of piles would depend on spacing,
depth and number of piles in each group.
It is also recommended that low energy Frequency Response dynamic pile integrity tests
be carried out on all piles before they are covered by a pile cap. It should be specified in
the tender document that these quality assurance tests be conducted by an independent
specialist consultant to detect potential structural defects such as voids, honeycombing or
cracks that would normally be detected by quality assurance procedures for reinforced
concrete that was accessible after casting.
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9.8 Drainage
A critically important factor in the stable development of the site is the control and
removal of both surface and groundwater and wastewater from the site.
Earthworks and drainage measures should be designed in such a way as to prevent ponding
of, or high concentrations of, stormwater or groundwater anywhere on the site, both during
and after the development. Stormwater from roofed and paved surfaces is to be led off site
into the nearest municipal stormwater connection facility or approved disposal position.
Under no circumstances is disposal by soakaway for stormwater and / or wastewater to be
considered.
Any terrace(s) should be shaped to a gradient to prevent water ponding on the surface and
should be graded to direct water away from the fill edges and foundations.
The need for subsoil drains and dewatering will need to be assessed on site during
construction in consultation with the geotechnical professional.
10. SUMMARY AND OBSERVATIONS
The following observation can be made about the site investigation:
i. The site is underlain by fill and residual material overlying weathered sandstone
rock.
ii. In terms of restrictions set down by the Department of Mines (1970), no building
should be constructed in an area in which mining activities occur or occurred within
a depth of 91m below EGL.
iii. It is advised that permission be requested from the Department of Mineral Resources
for the proposed development on the site.
iv. Founding options for the tower structure is discussed in Sections 9.7.
v. All construction activities on site need to be carried out in accordance with the
current version of SANS 1200.
The ground conditions given in this report refer specifically to the field tests carried out on
site. It is therefore, quite possible that conditions at variance with those given in this report
could be encountered elsewhere on site during construction. It is therefore important that
Geosure be appointed to carry out periodic inspections during construction. Any change
from the anticipated ground conditions could then be taken into account to avoid
unnecessary expense. Allowance should also be made for conducting a supplementary
geotechnical investigation of deep founding requirements for the proposed Tower anchor
points and obtaining advice on mining activities in the general vicinity of the site.
11. REFERENCES
i. Brink, A., & Bruin, R. (2002). Guidelines for Soil and Rock Logging in South
Africa. Proceedings of the Geoterminology Workshop. South Africa: Association of
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Engineering Geologists, South African Institute of Civil Engineering and South
African Institute for Engineering and Environmental Geologists.
ii. Google earth. (2018). AfriGIS (Pty) Ltd. Retrieved 27 06, 2019, from Google earth:
www.googlearth.com
iii. South African Bureau of Standards. (1990). Standard Specification for Civil
Engineering Construction, D: Earthworks. South Africa: South African Bureau of
Standards.
APPENDIX A
●●●●●●●●●●●●●●●●●●●●●
BOREHOLE PROFILES
●●●●●●●●●●●●●●●●●●●●●●●●●●●●
Geotechnical, Environmental & Groundwater Engineering Pile Integrity Testing & Civil Engineering Laboratory P O Box 1461, Westville, 3630, South Africa Tel: (031) 266-0458 Fax: 086 689-5506 email: geosure@ iafrica.com www.geosure.co.za
Roelf Fourie Geotechnical Services
Rotary Drilling of Boreholes for
Johannesburg Central Firestation, Gauteng
HOLE No: BH1
Sheet 1 of 1
HOLE No: BH1
Sheet 1 of 1
JOB NUMBER: J015-19JOB NUMBER: J015-19
0.50
0.00
1.00
1.95
3.00
8.20
10.00
Dark grey, dense, coarse, GRAVEL.
FILL (asphalt and boulders).
Pale brown to pale dark grey, soft, fine
grained, sandy SILT. FILL.
Reddish orange, medium dense,
medium to coarse grained, sandy
GRAVEL. Residual Sandstone with rock
fragments.
Pink to cream with yellowish orange
stains along joints, completely
weathered, medium to coarse grained,
highly fractured, very soft rock.
Quartzitic SANDSTONE (Central Rand
Group).
Pink to cream with yellowish orange
stains along joints, highly weathered,
medium to coarse grained, highly
fractured, soft to medium hard rock.
Quartzitic SANDSTONE (Central Rand
Group).
Pink to cream with opaque coarse
inclusions, highly weathered, coarse
grained, medium hard rock. Quartzitic
SANDSTONE (Central Rand Group).
Scale1:75
NOTES
1) Static Water Level: 5,4m.
2) Borehole terminated at 10,5m.
CONTRACTOR :MACHINE :
DRILLED BY :PROFILED BY :
TYPE SET BY :SETUP FILE :
RFG5
-N.Govender Pr.Sci.Nat. Reg No. 400138/17
P.KhaliliSTANDARG.SET
INCLINATION :DIAM :DATE :DATE :
DATE :TEXT :
-N10 June 201914 June 2019
28/06/19 08:36..C:\LOGS\BH1.TXT
ELEVATION :X-COORD :Y-COORD :
1745m28.04347 E26.21044 S
dotPLOT 6008 PBpD069 Geosure (Pty) Ltd
HOLE No: BH1
-
HOLE No: BH1
-
1
2
3
4
5
6
7
8
9
10
1744
1743
1742
1741
1740
1739
1738
1737
1736
1735
NXC
NWD4
-
-
96
100
100
96
100
-
-
46
57
25
70
0
-
-
9
16
14
DrillMethod
andSize
% CoreRec-overy
%RQD Frac-tureFre-
quency
DEPTHScale1:75