A REPORT - galagoenvironmental.co.za · A REPORT ON A GEOTECHNICAL ... of reddish brown sand/silt that is interpreted as colluvium. ... The test results indicate a mildly acidic environment

18120leachX2

A REPORT

ON

A GEOTECHNICAL INVESTIGATION

FOR THE PROPOSED TOWNSHIP OF LEACHVILLE EXTENSION 2

0N PORTION OF PORTION 148 OF THE FARM RIETFONTEIN 115-IR

EKURHULENI METRO MUNICIPALITY,

GAUTENG.

BY

RELLY, MILNER AND SHEDDEN

P R E T O R I A

DATE: JUNE 2018

TABLE OF CONTENTS

Page:

1. INTRODUCTION ... ... ... ... ... ... ... 1

2. SITE DESCRIPTION ... ... ... ... ... ... 1

3. GEOLOGY ... ... ... ... ... ... ... ... 2

4. EXISTING INFORMATION ... ... ... ... ... ... 2

5 SITE INVESTIGATION … … ... ... ... ... 2

6. LABORATORY TESTING ... ... ... ... ... ... 3

7. SOILS ... ... ... ... ... ... ... ... 3

8. BEDROCK ... ... ... ... ... ... ... ... 5

9. HYDROLOGY ... ... ... ... ... ... ... 5

10. GEOTECHNICAL DISCUSSION ... … ... ... ... 5

11. CONCLUSIONS AND RECOMMENDATIONS ... ... ... 10

12. GENERAL ... ... ... ... ... ... ... ... 17

APPENDICES

REGIONAL GEOLOGY ... ... ... ... ... ... ... A

SOIL PROFILES … … … … … … ... ... ... B

SUMMARY OF TECHNICAL INFORMATION ON MATERIALS ... … ... C

DETAILS OF POTENTIAL EXPANSIVENESS OF MATERIALS ... … ... D

CHEMICAL TEST RESULTS … … … ... … E

TABLE OF GEOTECHNICAL CONSTRAINTS … … … … … F

MAP … … … ... ... ... ... ... ... ... … G

1

1. INTRODUCTION

This report (18120leachX2) presents the results of a geotechnical investigation undertaken for

the proposed township of Leachville Extension 2 on portion of Portion 148 of the farm

Rietfontein 115-IR within the Ekurhuleni Metro Municipality (EMM) in Gauteng (see locality

plan overleaf).

The purpose of the investigation was to provide information on the nature and geotechnical

properties of the shallow soils encountered on the site.

This report has been prepared in accordance with a guideline published by the South African

Institute of Engineering and Environmental Geologists [SAIEG] (Reference 10) regarding the

establishment of townships in non-dolomitic areas.

The project was commissioned at the written request of Mr J Vorster of Metroprojects.

The fieldwork for this investigation was undertaken in April 2018.

2. SITE DESCRIPTION

The site is an irregular area of about 35 ha bounded by residential erven on the west

(Leachville), by portions of Rietfontein 115-IR in the east and south and by New Kleinfontein

Road in the north.

Access to the site is from New Kleinfontein Road on the northern side of the proposed township.

An extension of the existing Boven Avenue in Leachville provides access to the southern portion

of Leachville Extension 2 and via Waterval Street to join New Kleinfontein Road in the north.

The roads are all existing, surfaced, municipal roads. Access on the site is limited to these

existing roads.

The site is mostly undeveloped farmland with a row of residences along the western side of

Waterval Street on the eastern side of the proposed township. A soccer field and netball field

LOCALITY PLAN

LEACHVILLE EXTENSION 2, on portion of Portion 148 of the farm Rietfontein 115-IR, EKURHULENI METRO, GAUTENG.

THE APPROXIMATE SITE

2

have been created on a cover of fill towards the north-western corner. No structural

development other than the row of existing residences is present on the site.

The eastern and southern portions are covered in tall veld grass. A mixture of veld grass and

hydrophilic vegetation cover the central and western portions of the site. Several drainage

ditches have been created in the western half of the site to facilitate stormwater run-off.

The relief of the site is low with an overall cross-fall of about 8 m towards the north-east from

a high point in the south-west. The site has an overall gradient of about 1% but the southern

portion has a slightly steeper gradient at about 3%. The comment is based on information

obtained from the Ekurhuleni Metro Municipality GIS database.

3. GEOLOGY

According to the 1:250 000 Geological Map, Sheet No 2628 East Rand, sediments of the Vryheid

Formation, Ecca Group of the Karoo Supergroup underlie the site. The sediments comprise

mudrock, sandstone and coal.

A cover of colluvium and residual soil blankets the hard rock geology. No outcrops of rock were

observed on the site.

4. EXISTING INFORMATION

No geological reports covering the site could be sourced from the Council for Geoscience

databank.

5. SITE INVESTIGATION

The subsoil conditions for this project were investigated by means of ten shallow test pits. The

test pits were excavated using a Case 580G TLB supplied by TJ Plant Hire. The test pits were

terminated at a depth of about 2,5 m or at machine refusal on hardpan ferricrete. The depth

of the test pits ranges from 1,2 m to 2,8 m. Portions of the site were inaccessible for a TLB

3

because of saturated colluvium. Drainage ditches further restricted access to the western side

of the proposed township.

Detailed soil profiles were drawn up from an examination of the material observed in the test

pits by an engineering geologist according to recommended standard procedures (Reference

4).

Individual soil profile descriptions are given in the Soil Profiles in Appendix B and the position

of the test pits are shown on the map in Appendix G.

6. LABORATORY TESTING

Twelve disturbed soil samples were submitted to a soils laboratory for sieve analyses and

Atterberg limit determinations. The soils have been classified according to Unified Soil and T R

B classification systems and the results are summarised in the table in Appendix C.

Chemical tests to determine the pH and conductivity of the shallow soils were conducted on six

soil samples. The results are tabulated in Appendix E.

7. SOILS

The site is characterised by a variable soil profile. The southern third of the site has thick cover

of reddish brown sand/silt that is interpreted as colluvium. The northern two-thirds has a

mostly sandy profile that has undergone varying degrees of ferruginisation. Ferricrete caused

difficult excavation conditions in TP 1 and machine refusal in TP 10.

A generalised soil profile of the soil material encountered at the southern end of the site may

be described as:

0,0-0,4 m Moist, brown, medium dense, intact silty sand (colluvium) overlying

0,4-1,8 m moist to very moist, dark reddish brown, loose to medium dense in places, intact,

silty sand with scattered, soft, silt kernels (colluvium) overlying

1,8-2,6 m very moist, dark reddish brown to reddish brown, soft, intact, sandy silt with

4

abundant soft, silt kernels (colluvium).

The reddish brown sandy colluvium is intersected only in TP’s 2 and 3 located at the southern

end of the site. Groundwater prevented profiling below a depth of about 2,5 m. No evidence

of a change in soil type was observed towards the bottom of the two test pits.

The northern two-thirds of the site has a broadly similar profile that may be described as:

0,0-0,5 m Moist, dark grey, loose to medium dense, intact, silty sand (colluvium) overlying

0,5-0,6 m irregular gravel horizon of ferruginous concretions (pebble marker?) overlying

0,6-2,0 m moist, light grey mottled orange, medium dense to dense in places, intact, silty

sand with varying concentrations of ferruginous concretions (residual sandstone

and mudrock) overlying

>2,0 m beige, highly weathered, very soft rock sandstone in one or two test pits.

The soil profile in the northern portion tends to be more varied in terms of the degree of

ferruginisation and composition. Most of the soils tested as silty sand but some were more

clayey such as intersected in TP 7. The variability in composition is possibly related to

interfingering of thin sandstone and mudrock horizons. The overall sandy nature of the

residuum suggests the presence of sandstone bedrock at depth.

The top colluvial horizon is the same throughout the northern two-thirds. The layer is described

as dark grey, loose to occasionally medium dense, silty sand. A feature of this horizon, at the

time of the investigation, was the high moisture content. The colluvium and residual soil below

a depth of between 0,5 m and 1,0 m has a lower moisture content than above. It appears that

the top layer of sandy colluvium acts as a reservoir and stores a large volume of surface run-off

that then percolates downwards under gravity into the residuum. Impermeable layers of

ferruginised residuum cause the moisture to flow towards a low point at the northern end of

the township. The saturated top soil resulted in difficult access to TP 9 once the machine had

broken through the top 0,1 m to 0,2 m of the topsoil.

Bedrock was positively identified in two test pits.

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8. BEDROCK

Sandstone bedrock is intersected at depths of between 2,0 m and 2,5 m in TP’s 7 and 9. No

other test pits intersect bedrock.

9. HYDROLOGY

Groundwater seepage was observed in most test pits at depths ranging from 0,9 m (TP 4) to 2,4

m (TP’s 2, 3 and 9). Standing water hampered soil profiling in TP’s 2 and 4. The strongest flow

was observed from a small conduit at a depth of 0,9 m in TP 4. The water level rose from a

depth of 2,5 m to 1,33 m in 3 hours. Seepage in the other southern test pits occurred from

below a depth of about2,0 m.

Several drainage ditches containing standing water were observed in the south-western and

north-western portions of the proposed township. Access for the TLB was not possible over

most of the central and western parts of the site.

10. GEOTECHNICAL DISCUSSION

The following observations are based upon our interpretation of the conditions on the site, of the

soil materials sampled and the tests performed in the laboratory.

The NHBRC (Reference 7) has proposed a classification into which a site should be subdivided

according to the type and severity of the geotechnical problems and the founding solutions

required to solve the problems. The NHBRC classification has been adopted because of its

relevance to township development.

10.1 Collapsible Soil: Field evidence suggested the sandy/silty colluvium observed in TP’s 2 and

3 to be potentially collapsible should desiccation of the layer take place during a dry,

winter period. The soil horizons were too moist to allow undisturbed samples to be cut

6

from the sidewalls. Any consolidometer testing would have yielded little collapse but

significant “normal” (compressible) settlement. The thickness of the potential collapsible

layer is about 2,0 m.

The classification of the site follows those proposed by the NHBRC guideline as set out below

in Table 1.

TABLE 1

CLASSIFICATION OF SOILS SUBJECT TO COLLAPSE SETTLEMENT

NHBRC Profile

Classification

Estimated Total

Collapse Settlement

(mm)

C <5

C 1 >5 - <10

C 2 >10

(Differential movement = 75% of total settlement).

The site has been delineated into two classes namely, Classes C1 and C2. A strip of land in

the south has been delineated as Class C2. The northern area has been delineated as Class

C1 as the sandy colluvium tends to be thinner than in the south. The slightly ferruginised

layer with ferricrete concretions is the base of any potentially collapsible material.

10.2 Seepage: Shallow groundwater is likely to be encountered throughout the site

particularly during and at the end of a wet season. Appropriately located, impervious side

drains should ensure that stormwater run-off is directed towards the wetland without

entering the sandy topsoil layer. This layer acts as a vast reservoir for stormwater run-off

and allows the slow ingress into lower layers. The slow release of stored water into the

lower horizons results in shallow perched water tables for a large part of the year. Service

trenches are likely to be flooded and require stone drains to facilitate the installation of

services.

Adequate damp-proofing must be installed in all structures as the sandy topsoil layer is

often very moist to saturated in places. Consideration may be given to installing

7

agricultural drains on the upslope side of buildings to prevent an accumulation of water

against the foundations. This precaution may be regarded as essential where foundations

are placed on a layer of impermeable ferricrete below the sandy topsoil.

10.3 Potentially Expansive Soil (Active Soil): Field observations suggested the olive-coloured,

clayey layer intersected in TP 7 to be expansive. No potentially expansive soils were

observed in any of the other test pits.

Laboratory test results confirm the field observations and indicate the soils to be non-

expansive. The clayey soil, intersected in TP 7, although exhibiting a high liquid limit (>40),

does not classify as expansive.

Soil profiles may be classified according to the total potential heave (Reference 7) as

detailed below in Table 2.

TABLE 2.

NHBRC CLASSIFICATION OF EXPANSIVE SOILS

CLASS

ESTIMATED TOTAL HEAVE (mm)

H <7,5

H 1 >7,5 – 15

H 2 >15 – 30

H 3 >30

Differential movement = 50% total heave.

The site has been delineated into a single class namely, Class H.

10.4 Normal (Compressible) Settlement: Normal strip footings for structures should not be

considered for use on this site because of the compressible nature of the moist to very

moist colluvium. The high moisture content and loose consistency of the sandy colluvium

suggests that high normal settlement can be expected for any shallow strip foundations.

Strip footings are possible where horizons of shallow, hardpan ferricrete occur such as

around TP 10. However, the irregular extent of the ferricrete layer precludes an accurate

delineation of favourable founding areas. Care should be exercised to ensure a suitable

platform upon which to place floor slab where strip footings are to be considered.

8

The classification of the site follows those proposed by the NHBRC guideline for light

structures as set out below in Table 3.

TABLE 3

CLASSIFICATION OF SOILS SUBJECT TO CONSOLIDATION SETTLEMENT

NHBRC Profile

Classification

Estimated Total Settlement

(mm)

S <10

S 1 >10 - <20

S 2 >20


The site has been delineated as into two classes based on the thickness of the

compressible layer. The southern portion is delineated as Class S2 while the area to the

north is delineated as Class S1.

Individual investigations should be undertaken for large/heavy structures.

10.5 Erodibility of Soil: No evidence of erosion features such as gulleys, dongas or erosion

channels was observed on the site. The overall slope of the land is too gentle to create

high velocity run-off. The drainage ditches that criss-cross the western portion of the site

are all man-made and do not represent erosion gulleys.

10.6 Excavation Properties: Test pits were excavated by means of a Case 580G TLB and were

terminated at a depth of about 2,5 m or when excavation became difficult in ferruginised

soil or bedrock. Excavations up to 2,5 m deep should be possible throughout a substantial

portion of the site for a TLB. A large excavator (20 ton) should be capable of excavating

service trenches to depths of 3,0 m. Pockets of hardpan ferricrete may pose problems for

both a TLB and an excavator.

The limited use of pneumatic equipment may be required where pockets of shallow,

9

hardpan ferricrete are present (TP 10).

10.7 Undermining: Available information indicates that shallow mining has not taken place

below this site.

10.8 Soluble Rocks: Soluble rocks (dolomite) do not underlie the property.

10.9 Steep Slopes: No steep slopes are present on the site.

10.10 Unstable Natural Slopes: Unstable natural slopes are not present.

10.11 Seismic Activity: The site is located within an area classified as having a seismic intensity

of between V and VI on the modified Mercalli scale (MMS) with a 90% probability of an

event not being exceeded during a 100-year occurrence period. Expected peak ground

acceleration values associated with these magnitudes are given below:

• Magnitude V:Horizontal 34cm/s2Vertical17cm/s2

• Magnitude VI:Horizontal66cm/s2Vertical45cm/s2

Southern Africa is regarded as an area of low seismicity (Reference 3).

10.12 Flooding: No flooding should be expected on the site provided drainage ditches are kept

free of debris. Cognisance must be taken of the wetland buffer and 1 in 100-year floodline

to ensure development does not encroach beyond these boundaries. The downstream

flow of the wetland should not be impeded by future development.

Surface drainage should take place as sheetwash towards the north-east except along the

north-eastern edge where drainage is towards the north-west.

10.13 Sidewall Stability: All the test pits exhibited stable sidewalls to depths up to 2,8 m. The

moisture content of the natural soil in the ten test pits, at the time of fieldwork, was at a

level that favoured stable sidewalls.

10.14 Construction Material: The colluvium and residuum are too fine grained (A-4 to A-6) to

be regarded as quality construction material. Pockets of the ferruginised residuum may

10

meet G6 to G8 specifications but quantities are likely to be small relative to a large borrow

area. Some of material may be used as fill.

Detailed bulk testing would be required before any potential source of construction

material could be considered for exploitation. The potential loss of land should be

considered if material is to be borrowed on this site.

10.15 Road Subgrade: The layer of very moist, compressible colluvium from surface throughout

the site may hamper road construction. Some form of ground improvement is likely to

be required before a suitable road subgrade can be achieved.

10.16 Soil Chemistry: Certain conditions in the soil favour electro-chemical mechanisms which

increase the rate of corrosion. These conditions include the presence of acidic soil,

corrosive bacteria and electrolytes (chlorides and sulphates) which increase the soil

conductivity and decrease resistivity.

The test results indicate a mildly acidic environment with a range of pH values from 6,49 to

6,85. A pH of 7 is regarded as neutral.

The electrical conductivities (EC) of the soil material range from 12 mS/m to 140 mS/m and

the electrical resistivity values range from 714 ohms-cm to 8 333 ohms-cm. These values

indicate the corrosivity of the soil to range from slightly corrosive to very highly corrosive

(see Appendix E).

According to Beaton and Stratfull (Reference unknown), a 16-gauge metal culvert would

take between 28 years and 40 years to perforate if buried in the soils with the above

chemistry.

11. CONCLUSIONS AND RECOMMENDATIONS

The potential for excessive normal (compressible) settlement and high moisture content of the

top layer of colluvium represent the geotechnical conditions that need to be addressed in the

development of a township on this site. The site also has been classified according to the table

of geotechnical constraints published in Reference 8 (see Appendix F).

11

11.1 Collapsible Soils: The southern portion of the site has been classified as Class C2 because

of the potential of the moist to very moist colluvium to become collapsible when dry. The

remainder of the site is classified as Class C1.

The founding solutions for light structures in the various classes as recommended by the

NHBRC are given below in Table 4.

TABLE 4

RECOMMENDED CONSTRUCTION METHODS

NHBRC Profile

Classification

Estimated Total

Settlement (mm)

Recommended Construction Method

C <5 Normal Construction.

C 1 >5 – 10 Modified Normal; Compaction of in situ Soil;

Deep Strip Foundations or Soil Raft

C 2 >10

Stiffened or Cellular Raft; Deep Strip

Foundations; Compaction of in situ Soil; Piled

Construction or Soil Raft


The founding solutions recommended for light structures erected on Class C2 land are

given below.

• Stiffened Strip Footings, Stiffened or Cellular (waffle) Raft: Stiffened strip footings or

stiffened or cellular raft with articulation joints or lightly reinforced masonry. Bearing

pressure should not exceed 50 kPa. Mesh reinforcement in floor slabs. The site should

be properly drained and adequate plumbing and service precautions should be taken

to prevent leaks.

• Piled or Pier Foundations: Reinforced concrete ground beams or solid slabs on piled

or pier foundations. Ground slabs with fabric reinforcement. The site should be

properly drained and adequate plumbing and service precautions should be taken to

prevent leaks.

• In Situ Soil Compaction below Footings: Remove in situ soil to a depth and width of

1,5 times the foundation width or a competent horizon. Replace with suitable material

compacted to 93% MOD. AASHTO density at -1% and +2% of optimum moisture

content (OMC). The removed material may be suitable for replacement. Normal

12

construction with lightly reinforced strip foundations and masonry may be then

utilised.

• Deep Strip Footings: Found on a competent horizon below the problem layer using

normal construction but with the use of fabric reinforcement in floor slabs. Site should

be adequately drained.

• Soil Raft: Remove in situ material to 1,0 m beyond the structure to a depth of 1,5 times

widest foundation or to a competent horizon and replace with inert backfill compacted

at 93% Mod. AASHTO density at +2% to -1% of OMC. Normal construction methods

with lightly reinforced strip footings and light reinforcement in masonry may be then

utilised.

The founding solutions for Class C1 are the same as those detailed below in 11.4.

NHBRC Classification: C1/2. Geotechnical Constraint: 2A.

11.2 Seepage: Groundwater seepage should be expected from a depth of about 2,0m with

pockets of seepage from as shallow as 0,9 m in places (TP 4). Impervious drainage ditches

should be kept free of debris to allow stormwater run-off to be channeled into the

wetland. Every effort should be made to reduce the amount of run-off that infiltrates the

top layer of sandy colluvium.

Extensive perched water tables and flooding of service trenches are likely to be a problem

on this site and appropriate measures should be implemented to accommodate the

presence of groundwater.

Adequate damp-proofing should be installed in buildings. The use of agricultural drains

may be required where foundations are placed on impermeable ferricrete below the

sandy colluvial layer. Geotechnical Constraint: 1B.

11.3 Potentially Expansive Soils (Active Soil): No active soils were encountered in any of the

ten test pits. The site has been classified as Class H.

Table 5, on the next page, sets out the various foundation solutions according to the

13

profile classification in Table 2.

TABLE 5


NHBRC Profile

Classification

Estimated Total

Heave (mm)


H <7,5 Normal Construction below sand

H1 >7,5 – 15 Modified Normal or Soil Raft

H2 >15 – 30 Stiffened or Cellular Raft, Piled Construction,

Split Construction or Soil Raft

H3 >30 Stiffened or Cellular Raft, Piled Construction or

Soil Raft.

The entire site has been delineated as Class H. The clayey horizons intersected in TP 7

classify as non-expansive even though a high liquid limit, often associated with highly

active clay, is indicated.

NHBRC Classification: H. Geotechnical Constraint: 1C.

11.4 Normal (Compressible) Settlement: A portion of the southern half of the site has been

delineated as Class S2 because of the thick cover of compressible (loose/soft) colluvium.

The remainder of the site is classified as Class S1 provided foundations are placed below

the moist to very moist, sandy colluvium.

The recommended founding solutions for light structures for the various classes of normal

settlement are given in Table 6 on the next page.

The founding solutions recommended for light, single storey structures erected on

Class S1 land are given below:

• Modified Normal: Reinforced strip footings with articulation joints at some internal

and all external doors. The masonry should be lightly reinforced. Foundation

pressures should not exceed 50k Pa.

14

TABLE 6


NHBRC Profile

Classification

Estimated Total

Settlement (mm)


S <10 Normal Construction foundations placed

below topsoil.

S 1 >10 - <20 Modified Normal; Compaction of in situ

Soil; Deep Strip Foundations or Soil Raft

S 2 >20

Stiffened or Cellular Raft; Deep Strip

Foundations; Compaction of in situ Soil;

Piled Construction or Soil Raft

• In Situ Soil Compaction below Footings: Remove in situ soil to a depth and width of

1,5 times the foundation width or a competent horizon. Replace with suitable material

compacted to 93% MOD. AASHTO density at -1% and +2% of optimum moisture

content (OMC). The removed material is often suitable for replacement. Normal

construction with lightly reinforced strip foundations and masonry may then be

utilised.

• Deep Strip Footings: Found on a competent horizon below the problem layer using

normal construction but with the use of fabric reinforcement in floor slabs. Site should

be adequately drained.

• Soil Raft: Remove in situ material to 1,0 m beyond the perimeter of the structure to a

depth of 1,5 times widest foundation or to a competent horizon and replace with inert

backfill compacted at 93% Mod. AASHTO density at +2% to -1% of OMC. Normal

construction methods with lightly reinforced strip footings and light reinforcement in

masonry may then be utilised.

The founding solutions for Class S2 are the same as those detailed above in 11.1.

NHBRC Classification: S1/2. Geotechnical Constraint: 2D.

11.5 Erodibility of Soil: Field evidence does not indicate easily erodible soils. Soils should be

15

nevertheless protected from erosion. Geotechnical Constraint: 1E.

11.6 Excavation Properties: A mechanically sound TLB should be capable of excavating

trenches to a depth of 2,5 m below the surface except where pockets hardpan ferricrete

or ferruginised residuum occur (TP’s 1 and 10). A large excavator (20 ton) should be

capable of excavating trenches to greater than 3,0 m without difficulty although lenses of

hardpan may pose problems in places.

Pneumatic tools may be required where extensive lenses of hardpan ferricrete occur. An

excavation classification (SABS 1200) would see a sizable portion of the site being

classified as soft excavation for the top 2,5 m of the ground profile. An intermediate

classification may be more appropriate below a depth of 2,5 m. Geotechnical Constraint:

1F.

11.7 Undermining: The site is not undermined at a shallow depth. Geotechnical Constraint:

1G.

11.8 Soluble Rocks: Soluble rocks (dolomite) are not present within the top 100m of the soil

profile beneath the site. Geotechnical Constraint: 1H.

11.9 Steep Slopes: Steep slopes are not present. Geotechnical Constraint: 1I.

11.10 Unstable Natural Slopes: No unstable natural slopes occur on the site. Geotechnical

Constraint: 1J.

11.11 Seismic Activity: The potential for natural seismic activity is low. The site lies within an

area classified as having a natural seismic intensity of between V and VI on the modified

Mercalli scale (Reference 3). The possibility of mining induced seismicity cannot be

excluded as deep mining has taken place in the region. Geotechnical Constraint: 1K.

11.12 Flooding: Flooding is not expected provided cognisance is taken of the boundaries of the

wetland and buffer and the 1 in 100-year floodline. Poorly maintained drainage ditches

16

may result in localised flooding.

Surface drainage, in the form of sheetwash, should occur towards the north-east.

Sheetwash will be towards the north-west along the north-eastern edge of the site.

11.13 Sidewall Stability: Unstable sidewalls should not be expected in excavations shallower

than 1,5m unless excessive seepage water is encountered. Competent personnel must

inspect all excavations deeper than 1,5m.

The presence of ground water in any excavation is indicative of potentially unstable

conditions and must be treated with caution.

11.14 Construction Material: The shallow soils are mostly too fine grained to be of use as quality

construction material. The colluvium may be suitable for fill. Pockets of ferruginised

residuum may meet G6 to G8 specifications (Reference 2) but volumes are likely to be

small. Any exploitation of land may lead to a loss of valuable township land.

Detailed testing of any potential source will be required before exploitation is possible.

11.15 Road Subgrade: The sandy colluvium requires some form of ground improvement before

use as a road subgrade. The colluvium should be compacted to achieve 90% Mod AASHTO

for 0,0-0,5 m and 85% Mod AASHTO for 0,5-1,0 m. Adequate side drains and culverts are

required to ensure a road does not act as a barrier to groundwater movement.

11.16 Soil Chemistry: The chemical test results indicate the top 2,0 m of the soil profile to be

slightly corrosive to very highly corrosive towards galvanised pipes in terms of conductivity.

The soils exhibit a mildly acidic environment with pH values ranging from 6,49 to 6,85. A

pH of 7 is neutral.

Although numerous factors influence the aggressiveness of a soil environment, it is

recommended that plastic pipes rather than galvanised pipes be used for buried, water-

bearing services on this site in the light of the chemical results.

17

12. GENERAL

It must be borne in mind that an investigation of this nature is aimed at delineating broad areas

in which problems may occur. Consequently, certain generalisations must be made to avoid the

necessity of a costly investigation at every stand.

It may be found that soil conditions at variance with those discussed in this report do occur

locally. Competent personnel should inspect the variant conditions to ensure that these

conditions do not pose a problem for a specific development

The NHBRC requires a stand list indicating the soil classification for each stand as part of a

Phase 2 investigation to facilitate NHBRC enrolment. This investigation should run concurrently

with the installation of services. A refinement of the soil boundaries is possible at this stage.

E Shedden (Pr Sci Nat)

RELLY MILNER AND SHEDDEN JUNE 2018

REFERENCES/BIBLIOGRAPHY

1. BRINK, A.B.A. Engineering geology of Southern Africa. - Vol.3: The Karoo Sequence. -

Building Publications, Pretoria, 1983.

2. COMMITTEE OF STATE ROAD AUTHORITIES. –Guidelines for road construction materials. –

TRH 14, 1985.

3. FERNANDEZ, L.M. AND GUZMAN, J.A., - Earthquake hazard in Southern Africa. –

Seismological Series 10, Geological Survey of South Africa, 1979.

4. JENNINGS, J.E., BRINK, A.B.A. AND WILLIAMS, A.A.B., - Revised guide to soil profiling for civil

engineering purposes in South Africa. The Civil Engineer in S.A., Vol. 15 No. 1, January 1973.

5. JENNINGS, J.E. AND KNIGHT, K. - A guide to construction on or with materials exhibiting

additional settlement due to "Collapse" of grain structure. - 6th Reg. Conf. for Africa on Soil

Mech. and Found. Eng. Durban, South Africa, Vol. 1, pp 99 – 105, 1975.

6. JOHNSON, M.R., ANHAEUSSER, C.R. AND THOMAS, R.J. (Eds). – The geology of South Africa. –

Geological Society of South Africa/Council for Geoscience, Pretoria (2006).

7. NHBRC. – Home building manual, 2015.

8. PARTRIDGE, T.C., WOOD, C.K. AND BRINK, A.B.A. – Priorities for urban expansion within the

PWV metropolitan region: the primacy of geotechnical constraints. – South African

Geography Journal, Vol 75, 1993.

9. SAVAGE, P.E., Simplified Assessment of Settlement of Uniform Soil under Dwelling House

Foundations. - Unpublished paper, 1974.

10. SOUTH AFRICAN INSTITUTE OF ENGINEERING GEOLOGISTS (SAIEG). – Guidelines for urban

engineering geological investigations - 1st Issue, 1997.

11. SOUTH AFRICAN INSTITUTE OF ENGINEERING GEOLOGISTS (SAIEG). - A Short Workshop on

suggested interpretation techniques of soil movement with emphasis on heave and collapse

conditions. - CCI, Midrand, April 1999.

12. VAN DER MERWE, D.H., (MODIFIED BY P.E. SAVAGE) - The prediction of heave from Plasticity

Index and the percentage clay fraction, 1970.

APPENDIX A

REGIONAL GEOLOGY

REGIONAL GEOLOGY

LEACHVILLE EXTENSION 2, Ekurhuleni Metro, Gauteng.

Excerpt from 1:250 000 Geological Series, Sheet No: 2628 East Rand. [Not to scale]

Pv Mudrock and sandstone (Vryheid Formation - Ecca Group - Karoo Supergroup).

C-Pd Diamictite (Tillite) (Dwyka Group - Karoo Supergroup).

MUDROCK AND SANDSTONE

THE APPROXIMATESITE

APPENDIX B

SOIL PROFILES

Lithologic DescriptionPotential

SOIL PROFILE

Unified/

TRB Class.Expansiveness

Sa

mp

le N

o

67085

Elevation: 1629 mamsl

TEST PIT No:

X: 29019977

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:

RELLY MILNER and SHEDDEN, P O BOX 32107, GLENSTANTIA 0010, Tel: 012 9932049 Email: [email protected]

Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

1

es 6/4/2018Portion 148, Rietfontein 115-IR

18120leachX2

2,3m

Case 580G

1

TJ Plant Hire1) Difficult excavation at 2,3m in ferruginisedresiduum.2) Very slight seepage below 1,5m with slight butsteady flow at 2,15m.3) Fine roots in top 0,6m. Most vegetation clearedfor soccer field.

SC[A-4(1)]

(LOW)

LOW

(LOW)

2/1

0,0-0,6m: Moist, dark grey, medium dense, intact, silty SAND; colluvium.

0,6-1,2m: Moist to very moist, light grey mottled orange, loose, intact, silty SAND;colluvium(?).

1,2-2,3m: Medium and fine, subangular clast supported GRAVEL of hard, ferruginousconcretions in a minor matrix of very moist to wet, light grey mottled and blotchedorange, ferruginised, sandy silt; overall consistency is dense; residuum (ferruginised).

Grades into lenses of honeycomb and hardpan ferricrete in places.

Almost hardpan ferricrete below 1,8m.

EOH @ 2,3m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66972


TEST PIT No:

X: 2902486

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

2


18120leachX2

2,8m

Case 580G

2

TJ Plant Hire1) Hole stopped at 2,8m in silty colluvium. Norefusal.2) Standing water at 2,44m after 1 hour. No visibleflow above 2,44m.3) Fine roots in top 2,0m.

SC[A-4(2)]

(LOW)

LOW12/1

0,0-0,4m: Moist, brown, medium dense, intact, silty SAND; colluvium.

0,4-1,8m: Moist becoming very moist with depth, dark reddish brown, loose, intact,silty SAND with occasional soft, silt kernels below 1,7m; colluvium.

1,8-2,44m: Very moist to wet below 2,44m, dark reddish brown, loose, intact, siltySAND with traces of soft, silt kernels; colluvium(?).

2,44-2,8m: Standing water at 2,44m prevents sampling and hampers profiling below1,9m.

EOH @ 2,8m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66812


TEST PIT No:

X: 2902465

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

3


18120leachX2

2,6m

Case 580G

3

TJ Plant Hire1) Hole stopped at 2,6m in silty colluvium. Norefusal.2) Slight seepage visible at bottom of test pit. Nostanding water.3) Fine roots in top 2,0m.

SC[A-4(2)]

(LOW)

LOW

(LOW)

13/1

0,0-0,4m: Moist, brown, medium dense, intact, silty SAND; colluvium.

0,4-1,9m: Moist becoming very moist with depth, dark reddish brown, loose to mediumdense, intact, silty SAND with occasional soft, silt kernels below 1,5m; colluvium.

1,9-2,6m: Moist to very moist, reddish brown, firm, intact, sandy SILT with abundantsoft, silt kernels; colluvium(?).

EOH @ 2,6m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66891


TEST PIT No:

X: 2902357

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

4


18120leachX2

2,5m

Case 580G

4

TJ Plant Hire1) Hole stopped at 2,5m in silty colluvium. Norefusal.2) Standing water at 1,9m after 1 hour. Risen to1,33m after 3 hours. Flow from conduit at 0,9m andfrom entire sidewall below 1,0m3) Fine roots in top 0,9m.

(LOW)

0,0-0,5m: Very moist to almost wet, dark grey, loose, intact, silty SAND; colluvium(saturated).

0,5-0,9m: Very moist, light grey mottled orange, firm to soft, intact, sandy SILT withoccasional soft, silt kernels; colluvium.

0,9-1,33m: Moist to very moist, light grey blotched orange, dense to medium dense,intact, slightly ferruginised, silty SAND with abundant, hard, ferruginous concretions;residual mudrock (ferruginised).

Tends to gravel in places.

1,33-2,5m: Standing water from 1,33m after 3 hours.

EOH @ 2,5m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66771


TEST PIT No:

X: 2902362

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

5


18120leachX2

2,5m

Case 580G

5

TJ Plant Hire1) Hole stopped at 2,5m on ferruginised sandstone.2) Standing water at 2,35m after 0,3 hour. Flowfrom conduit at 2,2m. No flow above 2,2m.3) Fine roots in top 0,9m.

SC[A-2-4(0)]

SC[A-2-4(0)]

(LOW)

LOW

LOW

14/1

14/2

0,0-0,5m: Moist, dark grey, medium dense to loose, intact, silty SAND; colluvium.

0,5-1,1m: Moist to very moist, light grey blotched orange, firm, intact, silty SAND;colluvium(?).

1,1-2,35m: Moist to very moist, light grey mottled and blotched light orange and darkbrown, dense with medium dense pockets, intact, slightly ferruginised, silty SAND withabundant, hard, ferruginous concretions; residual mudrock (ferruginised).

Lenses of honeycomb ferricrete throughout profile.

2,35-2,5m: Standing water from 2,35 after 20 minutes. Standing water hamperedassessment of bottom horizon, assumed to be ferruginised sandstone.

EOH @ 2,5m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66816


TEST PIT No:

X: 2902230

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

6


18120leachX2

2,4m

Case 580G

6

TJ Plant Hire1) Hole stopped at 2,4m in silty residuum.2) Groundwater not encountered but top layer verymoist (saturated). TLB almost bogged down.3) Fine roots in top 0,9m.

CL[A-6(6)]

CL[A-6(3)]

(LOW)

LOW

LOW

10/1

10/2

0,0-0,5m: Very moist, dark grey, loose, intact, silty SAND; colluvium.

0,5-1,1m: Moist, olive, firm to stiff, intact, clayey SILT; colluvium.

1,1-2,4m: Moist, olive mottled grey and light orange, stiff, fractured, slightly clayey,sandy SILT with occasional, fine, ferricrete nodules; residual mudrock(?).

EOH @ 2,4m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66744


TEST PIT No:

X: 2902098

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

7


18120leachX2

2,3m

Case 580G

7

TJ Plant Hire1) Almost refusal at 2,3m on very soft rocksandstone .2) Groundwater not encountered but top layer verymoist (saturated).3) Fine roots in top 0,8m.

CL[A-7-6(7)]

CH[A-7-5(1)]

(LOW)

LOW

LOW

(LOW)

9/1

9/2

0,0-0,4m: Moist to very moist, dark grey almsot black, loose, intact, slightly clayey, siltySAND; colluvium.

Becoming more clayey with depth.

0,4-0,9m: Very moist, olive grey, firm becoming stiff with depth, intact, silty CLAY withscattered, fine gravel of ferricrete nodules; colluvium(?).

0,9-1,5m: Fine, subrounded, matrix supported GRAVEL of hard, ferricrete nodules andconcretions and occasional soft, calcareous concretions in an abundant matrix of olivemottled orange speckled black, very slightly ferruginised, clayey silt; pebble marker.

1,5-1,9m: Moist, olive grey mottled light orange, stiff, closely fractured, silty CLAY withscattered, fine gravel; residual mudrock.

1,9-2,3m: Beige, highly weathered, very soft rock SANDSTONE with lenses of oliveclay.

EOH @ 2,3m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66676


TEST PIT No:

X: 2901966

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

8


18120leachX2

2,3m

Case 580G

8

TJ Plant Hire1) Hole stopped at 2,3 in residual; silt. No refusal.2) Groundwater not encountered but top layer verymoist (saturated).3) Fine roots in top 0,3m.

SC[A-2-6(0)]

(LOW)

LOW

(LOW)

8/1

0,0-0,4m: Moist to very moist, dark grey, medium dense, intact, silty SAND; colluvium.

0,4-0,5m: Thin horizon of ferricrete GRAVEL; pebble marker(?).

0,5-0,8m: Moist, grey, medium dense, fractured, slightly clayey, silty SAND;residuum(?).

0,8-1,5m: Moist, light orange mottled and blotched light grey, stiff to firm in places,fractured, very slightly ferruginised above 1,0m, sandy SILT/silty SAND with scattered,hard, ferruginous conretions; residual mudrock.

1,5-2,0m: Moist, light orange mottled and blotched light grey, dense, intact, clayeySAND with lenses of clayey silt; residual gritstone(?).

2,0-2,3m: Moist to very moist, light grey blotched orange khaki and some dark grey,firm to stiff, closely fractured, clayey SILT; residual mudrock.

EOH @ 2,3m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66593


TEST PIT No:

X: 2902102

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

9


18120leachX2

2,4m

Case 580G

9

TJ Plant Hire1) Hole stopped at 2,4 in ferruginised sandstone.No refusal.2) Less than 15mm of standing water after 1 hour.Moisture visible below 2,2m.3) Fine roots in top 0,6m.4) TLB stuck in saturated, soft, top sandy layer.

SC[A-2-4(0)]

(LOW)

LOW

(LOW)

15/1

0,0-0,7m: Moist to very moist, dark grey, loose to medium dense with depth, intact,silty SAND; colluvium.

Becoming slightly clayey below 0,5m.

0,7-0,9m: Fine with some medium, subrounded, matrix supported GRAVEL of hard,ferricrete nodules and concretions in a minor matrix of moist, light grey mottled orange,slightly clayey, silty sand; overall consistency is dense to medium dense; pebblemarker(?).

0,9-1,8m: Moist, light grey mottled and blotched orange speckled black in places,dense, intact, very slightly ferruginised, silty SAND with scattered, hard, ferruginousconretions; residual mudrock(?).

1,8-2,3m: Moist, light khaki orange mottled light grey, dense, intact, very slightlyferruginised, silty SAND with scattered, hard and soft, ferruginous concretions; residualsandstone(?).

2,3-2,4m: Beige mottled brown, highly weathered, slightly ferruginised, very soft rockSANDSTONE.

EOH @ 2,4m.


SOIL PROFILE

Unified/


Sa

mp

le N

o

66154


TEST PIT No:

X: 29019975

Project:

Client:

Y:Coordinates Wgs:

Recorded by: Date:

Project No:

Location:L

ith

olo

gy

De

pth

(m

)

Page 1 of 1

Contractor:

Machine:

Test Pit No:

NOTES:


Total depth:

0,0

-0,5

-1,0

-1,5

-2,0

-2,5

-3,0

-3,5

29

Leachville Ext 2

Metroprojects

10


18120leachX2

1,2m

Case 580G

10

TJ Plant Hire1) Machine refusal at 1,2m on ferruginised residuum(ferricrete).2) Groundwater not encoountered.3) Fine roots in top 0,6m.

SC[A-4(1)] LOW

(LOW)

16/1

0,0-0,8m: Moist to very moist, dark grey, loose to medium dense, intact, silty SAND;colluvium.

Becoming slightly clayey with depth.

0,8-1,0m: Moist to very moist, light grey to grey mottled orange, medium dense,fractured, slightly clayey, silty SAND; colluvium(?).

1,0-1,2m: Fine, subrounded, matrix supported GRAVEL of hard and soft, ferruginousconcretions in a minor matrix of moist, light grey blotched orange, sandy silt; overallconsistency is medium dense to dense; pebble marker(?).

EOH @ 1,2m.

>1,2m: Grades into lenses of dense, ferruginised residuum and hardpan ferricrete.

APPENDIX C

SUMMARY OF TECHNICAL INFORMATION ON MATERIALS

SUMMARY OF TECHNICAL INFORMATION ON MATERIALS PROJECT: LEACHVILLE EXTENSION 2

SITE: Portion of Portion 148, RIETFONTEIN 115-IR,

Ekurhuleni Metro Municipality, GAUTENG.

SIEVE ANALYSIS SOIL MORTAR CONSTANTS CLASSIFICATION POTENTIAL

HOLE SAMPLE DEPTH MATERIAL (% PASSING) ANALYSIS (%)

EXPANSIVE-

No. No. (m)

DESCRIPTION

63,0mm

50,0

mm

37,5mm

28,0mm

20,0

mm

14,0mm

5,0

mm

2,0

mm

0,425

mm

0,075mm

0,002

mm

2.00

-

0,425

0,425-

0,25

0,25

-

0,15

<0,075

LL PI LS GM T.R.B. UNIF NESS

TP 1 2/1 0,6-1,2 Silty SAND 100 93 83 72 38 18 15 8 15 44 26 8 4,0 1,05 A-4(1) SC LOW



TP 5 14/1 0,5-1,1 Silty SAND 100 97 92 83 33 25 10 13 17 36 22 9 4,4 0,92 A-2-4(0) SC LOW

14/2 1,1-2,35 Gravelly SAND 100 96 71 60 51 24 20 14 11 13 40 24 8 3,9 1,66 A-2-4(0) SC LOW

TP 6 10/1 0,5-1,1 Clayey SILT 100 99 89 60 41 9 10 12 61 35 13 6,5 0,52 A-6(6) CL LOW

10/2 1,1-2,4 Sandy SILT 100 99 90 48 41 9 20 13 49 30 11 5,7 0,62 A-6(3) SC LOW

TP 7 9/1 0,4-0,9 Silty CLAY 100 98 88 78 53 37 11 11 9 60 44 19 8,8 0,81 A-7-6(7) CL LOW

9/2 0,9-1,5 Gravelly CLAY 100 99 82 59 52 38 33 13 7 8 65 55 11 5,6 1,51 A-7-5(1) CH LOW

TP 8 8/1 0,8-1,5 SAND/SILT 100 88 80 70 24 29 12 15 20 30 29 11 5,5 1,27 A-2-6(0) SC LOW

TP 9 15/1 0,9-1,6 Silty SAND 100 99 78 68 57 30 16 16 11 11 44 23 7 3,5 1,45 A-2-4(0) SC LOW

TP 10 16/1 0,0-0,8 Silty SAND 100 98 85 39 13 14 11 18 10 16 5 2,5 0,78 A-4(1) SC LOW

RELLY MILNER AND SHEDDEN PO Box 32107 GLENSTANTIA 0010 Tel: 012 99312 2049 Cellular: 082 551 6034 Email: [email protected]

0,15

-

0,075

17

18

20

25

22

8

9

9

7

23

18

17

APPENDIX D

DETAILS OF POTENTIAL EXPANSIVENESS OF MATERIALS

DETAILS OF POTENTIAL EXPANSIVENESS OF MATERIALS PROJECT: LEACHVILLE X2

LOCATION:Ptn of Ptn 148, RIETFONTEIN 115-IR, Ekurhuleni Municipal Metro, GAUTENG.

PROFILE No. SAMPLE No. DEPTH OF SAMPLE (m)

THICKNESS OF LAYER (m)

POTENTIAL EXPANSIVENESS

PREDICTED HEAVE (mm)

TOTAL PREDICTED HEAVE (mm)

RELLY MILNER AND SHEDDEN P O Box 32107 GLENSTANTIA 0010 Tel: 012 9932049 Fax: 086 534 9513 Cellular: 082 551 6034

NO EXPANSIVE SOILS ENCOUNTERED ON THE SITE (within the depths excavated).

APPENDIX E

CHEMICAL TEST RESULTS

CHEMICAL TEST RESULTS

TEST

PIT

SAMPLE

No.

DEPTH

(m)

pH

CONDUCTIVITY

mS/m

RESISTIVITY

Ω-cm

CORROSIVENESS

TP 1 2/1 0,6-1,2 6,71 25 4 000 MC

TP 3 13/1 0,4-1,9 6,63 12 8 333 SC

TP 5 14/2 1,1-2,35 6,70 16 6 250 SC

TP 6 10/2 1,1-2,4 6,85 140 714 VHC

TP 8 8/1 0,8-1,5 6,81 76 1 316 HC

TP 10 16/1 0,0-0,8 6,409 13 7 692 SC

According to authors Beaton and Stratfull (reference unknown) and based on the above

results, a 16-gauge metal culvert would take between 28 years and 40 years to corrode if

located within the soils encountered in the test pits indicated in the above table. It should be

noted that the above factors are not the only ones which influence the rate of corrosion. High

soil moisture contents and corrosive bacteria may also be present which could substantially

increase the rate of corrosion.

Table of Corrosiveness

Conductivity

Resistivity

Corrosiveness

>110 mS/m

110 - 45 mS/m

45 - 20 mS/m

20 - 10 mS/m

<10 mS/m

0 - 900 Ω-cm

900 - 2300 Ω-cm

2300 - 5000 Ω-cm

5000 - 10000 Ω-cm

>10000 Ω-cm

Very Highly corrosive (VHC)

Highly corrosive (HC)

Medium corrosive (MC)

Slightly corrosive (SC)

Non-corrosive (MC)

The conductivity and resistivity values indicate the soil to range from slightly corrosive to very

highly corrosive.

APPENDIX F

TABLE OF GEOTECHNICAL CONSTRAINTS

APPENDIX G

MAP

Documents

A REPORT - galagoenvironmental.co.za · A REPORT ON A GEOTECHNICAL ... of reddish brown sand/silt that is interpreted as colluvium. ... The test results indicate a mildly acidic environment