REPORT ON THE RESULTS OF A GEOTECHNICAL SITE … · 2019. 1. 9. · PROPOSED HELMSLEY RESIDENTIAL COUNTRY ESTATE DEVELOPMENT – BALLITO. October 2018 Davies Lynn & Partners (Pty)

Reference

18/N8514

Prepared By

C. Ross / N. Tonkin

Date

October 2018

REPORT ON THE RESULTS OF A

GEOTECHNICAL SITE

INVESTIGATION FOR THE

PROPOSED HELMSLEY

RESIDENTIAL COUNTRY ESTATE

DEVELOPMENT - BALLITO

October 2018 Davies Lynn & Partners (Pty) Ltd Page ii

Ref. 18/N8514

REVISION HISTORY

Date Rev No. Description Revised By

10/2018 A Creation of New Document C.J.R / N.D.T

October 2018 Davies Lynn & Partners (Pty) Ltd Page iii

Ref. 18/N8514

TABLE OF CONTENTS

1. TERMS OF REFERENCE .................................................................................................................................... 1

2. SCOPE OF WORK ................................................................................................................................................. 1

3. INFORMATION SUPPLIED ................................................................................................................................ 1

4. SITE DESCRIPTION ............................................................................................................................................. 2

5. SUBSURFACE GEOTECHNICAL INVESTIGATION ..................................................................................... 2

6. GEOLOGY AND SUBSOILS ................................................................................................................................ 3

6.1 OVERVIEW ............................................................................................................................................................ 3 6.2 COLLUVIAL TOPSOIL ............................................................................................................................................. 3 6.3 NATAL GROUP SANDSTONE .................................................................................................................................. 3 6.4 DWYKA TILLITE/DIAMICTITE ................................................................................................................................ 4 6.5 POST KAROO DOLERITE ........................................................................................................................................ 5

7. GROUNDWATER .................................................................................................................................................. 6

8. LABORATORY TESTING ................................................................................................................................... 6

9. EXCAVATABILITY .............................................................................................................................................. 8

10. PROPOSED DEVELOPMENT ............................................................................................................................. 9

11. FOUNDING RECOMMENDATIONS ................................................................................................................. 9

11.1 EARTHWORKS .................................................................................................................................................. 9 11.1.1 Excavatability ......................................................................................................................................... 9 11.1.2 Embankment Construction ................................................................................................................... 10

11.2 FOUNDING ...................................................................................................................................................... 11 11.2.1 Founding Conditions ............................................................................................................................ 11 11.2.2 Founding Recommendations ................................................................................................................ 12

12. PROPOSED RESERVOIR SITE ........................................................................................................................ 13

13. PROPOSED WATER TREATMENT WORKS SITE ...................................................................................... 14

14. ROADS ................................................................................................................................................................... 15

14.1 ROAD EARTHWORKS ...................................................................................................................................... 15 14.1.1 Excavatability ....................................................................................................................................... 15 14.1.2 Embankment Construction ................................................................................................................... 15

14.2 ROAD SUBGRADE ASSESSMENT ..................................................................................................................... 16 14.2.1 Subgrade .............................................................................................................................................. 16 14.2.2 Layerworks ........................................................................................................................................... 17 14.2.3 General ................................................................................................................................................ 17

14.3 SUBSOIL DRAINAGE ....................................................................................................................................... 18

15. ENGINEERING SERVICES ............................................................................................................................... 18

15.1 EARTHWORKS ................................................................................................................................................ 18 15.1.1 Excavatability ....................................................................................................................................... 18 15.1.2 Backfill Material Assessment ............................................................................................................... 18

October 2018 Davies Lynn & Partners (Pty) Ltd Page iv

Ref. 18/N8514

APPENDICES

APPENDIX 1 Test Pit Logs

APPENDIX 2 Laboratory Test Results

DRAWINGS 18/N8514-01 Geotechnical Site Plan

REPORT ON THE RESULTS OF A GEOTECHNICAL SITE INVESTIGATION FOR THE

PROPOSED HELMSLEY RESIDENTIAL COUNTRY ESTATE DEVELOPMENT –

BALLITO.

October 2018 Davies Lynn & Partners (Pty) Ltd Page 1

Ref. 18/N8514

1. TERMS OF REFERENCE

Davies Lynn and Partners (Pty) Ltd (DLP) were requested by Bigen Africa (Pty) Ltd to

undertake a Phase 1 Geotechnical Site Investigation for the proposed new Helmsley

Residential Country Estate Development near Compensation, Ballito. The geotechnical

proposal was submitted by Davies Lynn & Partners (Pty) Ltd to Bigen Africa (Pty) Ltd

on 10th

September 2018 and referenced 18/N8514. The quotation was subsequently

accepted and DLP were authorised to proceed with the investigation.

2. SCOPE OF WORK

This report documents the findings of the geotechnical investigation that was carried out

at the site of the proposed new Helmsley Residential Country Estate Development near

Compensation, Ballito.

Accordingly, the scope of this Geotechnical Report is as follows:

▫ to present all the fieldwork and laboratory testing carried out during the

geotechnical investigations;

▫ to assess the geotechnical and geological conditions of the subsoil materials

across the site of the proposed Housing Development with respect to the

development of structures, roads, slope stability and engineering services;

▫ to recommend sound economical development practices and founding guidelines

for the proposed development based on the geotechnical conditions that are

encountered.

3. INFORMATION SUPPLIED

The following information was supplied to Davies Lynn & Partners (Pty) Ltd to assist

with the investigation:

➢ A detailed drawing was provided, titled “Locality Map Project Context”, prepared

by Bigen Africa (Pty) Ltd, dated April 2018, Drawing No. 0938.00AA.01A012.

➢ A Site Layout Plan was provided, titled “Phasing Layout Plan” prepared by

Bigen Africa (Pty) Ltd, dated May 2013, Drawing No. 0938.00ZA.01A014.

➢ A Satellite image was similarly provided with an overlay of the proposed site

layout.



BALLITO.


Ref. 18/N8514

4. SITE DESCRIPTION

The proposed Housing Development is located on the Helmsley Farm Compensation,

Ballito.

The proposed Helmsley Residential Country Estate DDevelopment is anticipated to

comprise of three (3No.) Phases with a total of fourty two (42No.) Freestanding

Residential Homes and three (3No.) Planned Unit Development (PUD) Sites. The land

is currently undeveloped and is partially covered by sugar cane plantations and open

undeveloped grassed fields with interspersed shrubs and trees.

Topographically, the site slopes towards the south east, with development mainly

confined along the two (2No) south east trending ridge lines. Slopes vary across the site

from gently sloping ridge lines to moderately to steeply sloping hillside slopes and valley

head areas.

5. SUBSURFACE GEOTECHNICAL INVESTIGATION

The fieldwork for the subsurface geotechnical investigation comprised the following:

i. Excavation, profiling and backfilling of Inspection Pits (IP’s) across the proposed

site. During the investigation, twenty-two (22No.) Inspection Pits (IP’s) were

excavated by TLB to depths ranging between approximately 2m and up to 3.2m

below existing ground levels for the purpose of geotechnical profiling and material

sampling. The logs of the Inspection Pits are presented in Figures 1.1 to 1.22 in

Appendix 1 of this Report.

ii. Twenty-two (22No.) Dynamic Cone Penetrometer (DCP) tests were performed

immediately adjacent to the twenty-two (22No.) Inspection Pits. The DCP tests

were undertaken adjacent to the Inspection Pits in order to assess and correlate the

relative densities of the subsurface materials across site with the profiled

descriptions from the Inspection Pits. The DCP tests were performed to depths of

refusal or to a maximum depth of approximately 3m below existing ground levels.

The DCP test results are presented together with the Inspection Pit logs in Figures

1.1 to 1.22 in Appendix 1 of this report.

iii. Material sampling of representative subsoils was undertaken from the Inspection Pit

excavations and were transported to a commercial soils testing laboratory for Sieve

analyses, Hydrometer analyses, Atterberg Limits, Natural Modified AASHTO

maximum dry density compaction tests and California Bearing Ratio (CBR) tests.



BALLITO.


Ref. 18/N8514

Selected undisturbed samples were taken for Collapse and Swell Potential tests.

The results of the Laboratory Tests are included in Appendix 2 of this report.

The locations of the various in-situ tests in relation to the proposed development

are indicated on the Geotechnical Site Plan Dwg. No. 18/N8514-01 enclosed.

6. GEOLOGY AND SUBSOILS

6.1 Overview

The Natal Group Sandstone sequence and its related subsoils mainly underlie the site of

the proposed new development, with Dwyka Group Tillites confined to the south and

south western portions of the site. The Natal Group Sandstone sequence is

approximately 250 to 490 million years old and therefore, over time, has been exposed

to a multitude of different environmental and geological conditions. The geology of the

site is characterised by colluvial topsoil overlying residual clayey subsoils that have

undergone a protracted period of weathering to form a lateritic profile, which in turn

overlie weathered Sandstone bedrock at depth.

6.2 Colluvial Topsoil

The colluvial topsoil horizon comprises slightly moist, dark brown, soft to stiff, silty

SANDY CLAY to moderately clayey SAND which was found to cover the entire site to

depths ranging between approximately 0.2m and up to 1.5m below existing ground

levels. This horizon was found across all three (3No.) Geotechnical Zones.

6.3 Natal Group Sandstone

The majority of the development area is underlain by the Natal Group Sandstones.

Colluvial and residual clayey SAND to SANDY CLAY horizons form the sub-soil cover

of the Natal Group Sandstone bedrock. These soil covers extend to depths of up to 2,2

metres across these portions of the site, with the Hilltop areas consisting of a thinner

colluvial horizon ranging between 0.3m to 1m in depth before weathered, soft to

medium hard rock Sandstone bedrock is encountered.

The depth at which the Sandstone bedrock is encountered across the site, is typically

governed by topographical relief.



BALLITO.


Ref. 18/N8514

The subsurface profile typically comprises a dry, pale grey brown, intact, medium

dense, silty fine SAND underlain by a dry to slightly moist, reddish brown to red

mottled orange, nodulised, dense, slightly to moderately clayey SAND (residual

Ferricrete), which in turn underlain by Sandstone bedrock. The bedrock unit typically

occurs either as completely weathered, residual rock, or becomes progressively less

weathered with increasing depth or moderately weathered, hard rock lying close to

surface.

The occurrence of fine grained sandy soils (where collapse potential is possible)

overlying weathered sandstone bedrock, classify the NHBRC founding conditions as

Category C1 (beneath the areas where shallow soils prevail above bedrock), and

Category C2 (where thicker soil cover prevails and the potential for collapse type

settlements exceed 20mm.) These areas shown diagrammatically in Figure D.

Composite Site Classes leading to possible higher differential movements will occur

across cut / fill platforms, where bedrock is exposed in the deeper cut portion and

colluvial and residual soils occur towards the cut / fill line. NHBRC Class R/H2

designations occur where thicker potentially active residual clayey sub-soils occur

overlying the Sandstone bedrock.

6.4 Dwyka Tillite/Diamictite

The Dwyka Group Tillite / Diamictite bedrock is typically found confined to the south

and south-western portions of the site and is generally highly to completely weathered

and of very soft rock strength near the ground surface. Scattered hard corestones and

boulders occur within a silty and clayey residium in certain areas. The soil cover

typically varies between 0,1m and up to 2m depth with topographical variance across

the site.

The NHBRC Site Class Classification in the areas underlain by Dwyka Group Tillite /

Diamictite varies from C1/S1 where shallow sandy and silty colluvium overlies Tillite /

Diamictite bedrock to C2/S2 and / or H2 where deep colluvium / residual soil overlies

bedrock. The NHBRC guidelines Table 3 designates these fine grained soils as

potentially compressible and collapsible where total anticipated soil movements in the

range 5mm to >10mm are possible. Class H2 designations occur where thicker

potentially active colluvial and residual clayey soils occur above the bedrock. The

landform in the area typically requires that cut to fill platforms are undertaken to create

building platforms.

Accordingly, these platforms are likely to expose the Tillite / Diamictite bedrock in the

deeper cut portions of the layout, whilst colluvial and residual soils will be exposed

towards the cut / fill line. The NHBRC class designates are likely to be R/H2 or R/C2,



BALLITO.


Ref. 18/N8514

etc. where Tillite / Diamictite bedrock is exposed in the deep cut portions of the

platforms whilst residual soils are likely to occur adjacent to the cut/fill portion of the

layout.

6.5 Post Karoo Dolerite

Post Karoo Dolerite intrusions were not encountered during the geotechnical site

investigation, however, according to the Geological 1:250 000 map, Dolerite capping is

shown on the elevated north western portion of the site. Residual Dolerite clays are

characteristically expansive and thus prone to heave (swell) and shrinkage movements

in response to moisture level fluctuations.

Saprolitic silty clays often characterise the doleritic residium. These soils are prone to

consolidation settlement under load and hence special founding requirements are

required for development on these soils.

Figure 1: Site Geology according to the 1:250 000 Geological Series.



BALLITO.


Ref. 18/N8514

7. GROUNDWATER

No groundwater was encountered across all of the proposed three (3No.) Phases of the

site, during the geotechnical field investigation. Owing to its elevation, the site is

considered to be well drained; however, the rock jointing and soil profile of the

weathered Natal Group Sandstone and/or Dwyka Group Tillite / Diamictite sequence

makes the area susceptible to the development of localized perched water tables,

particularly after heavy rain.

Groundwater seepage was however, encountered in the lower topographical area of the

proposed Waste Water Treatment Works (WWTW) at a depth of approximately 1,5m

below existing ground level. Consideration of this will need to be taken into account

during the design and construction phases of the proposed WWTW.

8. LABORATORY TESTING

In order to classify the major subsoil materials and to assess their suitability for use in

earthworks and road construction, laboratory testing was undertaken on six (6No.)

disturbed and six (6No.) undisturbed samples of soil.

The laboratory testing comprised the following:

▫ Sieve Analyses,

▫ Hydrometer Analyses,

▫ Atterberg limits,

▫ Moisture Contents

▫ Natural Mod. AASHTO maximum dry density compaction tests;

▫ California Bearing Ratio (CBR) tests;

▫ Collapse Potential;

▫ Swell Potential.

A summary of the results of the mechanical size analysis, compaction tests, CBR tests,

Collapse Potential and Swell Potential, are given below with results of the laboratory

testing presented in Appendix 2. The implications of these results, in terms of material

assessment and classification applicable to the proposed development, are briefly

discussed below and, in more detail, subsequently in the relevant sections of this report.

Table 1, overleaf, summarizes the results of the laboratory test results of subsoils

sampled during the geotechnical investigations. Plasticity Indices (PI) of the materials

tested typically ranged between 6% and 33% and Liquid Limits (LL) typically ranged



BALLITO.


Ref. 18/N8514

between 18% and 64%, while the grading moduli ranged between 0.52 and 1.50.

Linear Shrinkages varied from 3% and 14% in the tested subsoils.

Table 1: Summary of Laboratory Test results

Sample No. T12658 T12659 T12660 T12661 T12662 T12663

Field Position IP2 IP4 IP7 IP8 IP11 IP16

Sample Depth

(m)

0m–

1.5m

0.6m–

1.3m

0.7m –

2.0m

0.9m –

2.2m

0.6m–

1.3m

0.6m–

1.6m

Material

Description

Dk.

Grey,

silty

clayey

Sand

Rd. Or.

Brown

sandy

Clay

Pale

Olive

Brown

Gravelly

Clay

Pale Yl

Or. Brown

mod.

Clayey

SAND

Dark

grey Or.

Brown

sandy

silty

CLAY

Rd.

Brown

very

sandy

CLAY

Origin

Colluvial

Topsoil

Residual

Laterite

Residual

Dwyka

Tillite

Residual

Sandstone

Residual

Clay

Residual

Sandstone

Soil M

ortor

% Coarse

Sand

51 19 19 51 6 30

% Coarse

Fine

Sand

15 10 6 9 3 6

%

Medium

Fine

Sand

8 6 8 5 3 4

% Fine

Fine

Sand

6 5 10 3 5 4

% Silt &

Clay

21 60 58 32 82 56

% Clay 9 45 - - 56 38

Liquid Limit % 18 44 26 31 64 41

Plasticity

Index %

6 19 10 12 33 15

Linear

Shrinkage %

3 10 5 6.5 14 8.5



BALLITO.


Ref. 18/N8514

Grading

Modulus

1.33 0.60 1.50 1.28 0.52 0.91

Maximum Dry

Density (kg/m3

)

2062 1812 1976 2020 1823 1836

Optimum

Moisture

Content (%)

8.8 16.2 8.8 10.8 20.6 15.7

CB

R at %

M

od.

AA

SH

TO

100% 22 9.9 21 5.8 1.6 14

98% 18 5.9 13 3.2 1.2 10

97% 17 4.5 10 2.4 1.1 8.6

95% 14 2.7 6.2 1.3 0.8 6.0

93% 12 1.6 3.8 0.7 0.6 4.3

90% 9.3 0.7 1.8 0.3 0.4 2.5

Maximum

Swell (%)

0.0 0.3 0.8 0.7 2.4 0.7

Group Index

Classification

A-1-b(0)

A-7-

6(11)

A-4(0) A-2-6(0)

A-7-

5(26)

A-7-6(5)

TRH 14

Classification

G8 <G10 <G10 <G10 <G10 <G10

Unified

Classification

SM-SC CL SC SC CH ML/OL‡

The colluvial soils exhibited Collapse Potentials in the range of 0.11% to 0.21% for the

samples tested.

The Collapse Potential for the Residual Sandstone materials tested ranged from

between 0.18% and 0.48% with a Swell Potential of the residual Sandstone Clays

sampled at IP 4 of 4.62 kPa.

The residual Tillite / Diamictite Clay sampled at IP 11 exhibited a higher Swell Potential

of 6.32kPa.

9. EXCAVATABILITY

The final depths of the Inspection Pits excavated during the geotechnical investigation

(maximum 3.2m below ground level) gives a good indication of the depth to which



BALLITO.


Ref. 18/N8514

excavations can be carried out with relative ease by a TLB (back-acting excavator) or

similar plant.

Based on the above, as well as engineering experience with subsoils of similar nature,

the classes of excavatability which should be expected and catered for during

excavations into the various materials on site is given below.

The colluvial topsoil and residual Sandstone / Tillite / Diamictite subsoils (typically

encountered within Geotechnical Zones 2 and 3) are considered to be easily

excavatable. In other words, these materials classify as soft in terms of SABS 1200 DA

criteria. Notwithstanding this, materials classifying as intermediate could be encountered

where re-cementation of the residual soils is well formed or where the consistency of the

clayey subsoils has increased due to drying out during months of drier conditions.

Completely weathered Sandstone / Tillite / Diamictite bedrock is expected to range from

soft to intermediate in terms of SABS 1200 DA criteria, while medium to highly

weathered Sandstone / Tillite / Diamictite bedrock could classify as hard, depending on

bedding and joint spacing as well as the nature of the bedrock present. Where relatively

hard Sandstone / Tillite / Diamictite occurs within less than 1m of the surface (within

Geotechnical Zone 1) there is a potential for heavy ripping and / or blasting.

10. PROPOSED DEVELOPMENT

The proposed Helmsley Residential Country Estate Housing Development is anticipated

to comprise freestanding residential single and double storey homes as well as three

(3No.) Planned Unit Developments (PUD). Additionally, the proposed Reservoir and

Waste Water Treatment Works sites were investigated with an Inspection Pit excavated

at each site. No detailed drawings of the proposed structures were provided at the time

of writing this Report.

11. FOUNDING RECOMMENDATIONS

11.1 Earthworks

11.1.1 Excavatability

For the excavatability characteristics of the insitu materials in terms of earthworks for

platform construction, refer to Section 9 of this Report.



BALLITO.


Ref. 18/N8514

11.1.2 Embankment Construction

Given the varying slopes, cut to fill platforms are likely to be required across the

majority of the site, in order to facilitate construction of the proposed residential

structures. It is recommended that all earthworks and embankment construction be

carried out in accordance with recommendations given in the current SABS 1200

series.

In general, the insitu subsoils present across the site are suitable for construction of

embankments and terraces in terms of SABS 1200 D criteria. Notwithstanding this, the

following precautions are strongly advised:

▫ Residual Sandstone / Tillite / Diamictite clays should not be used for embankment

and terrace construction.

▫ The top 0.2m to 1.5m of topsoil should be removed and stockpiled for later use.

▫ Boulders or rock fragments greater than 150mm in size should be removed.

▫ The placement of the fill should be in layers not exceeding 200mm, individually

compacted at optimum moisture content to 93% Mod. AASHTO maximum dry

density.

All vegetation and topsoil should be cleared from the areas over which fill is to be

placed. This material should be stockpiled for later use as topsoil and for landscaping. In

the event that fill is to be placed onto loose material, it is recommended that the ground

surface should be well compacted before commencing fill placement. Where the natural

ground slopes exceed 1:6 (approximately 9

degrees), fill should be benched into the

insitu material to promote compaction and stability.

Regular compaction density control tests should be undertaken during development of

fill embankments as set down in SABS 1200 series guidelines.

Where slightly to moderately weathered Sandstone / Tillite / Diamictite bedrock is

excavated, this material should be broken down and stockpiled for use as rock fill in the

lower layers of road embankment fills. Alternatively, rock fill could also be used in the

lower layers of the embankments and terraces provided that all rock fragments greater

than 600mm are screened out. It is important to ensure that the voids inherent in these

poorly sorted rock fill materials are completely choked with finer materials during

compaction.

The topsoil referred to above should be placed onto embankments after construction

and vegetated as soon as possible to promote stability and limit erosion.



BALLITO.


Ref. 18/N8514

The following batters are recommended:

▫ 1:2 (26

degrees) for fill embankments subject to maximum height of 1.5m

▫ 1:3 (18


▫ 1:2 (26

degrees) for cuts within subsoils subject to maximum height of 1.5m

▫ 1:1.5 (34 degrees) for cuts within highly weathered bedrock (depending on joint

and bedding orientation)

▫ 1:1+ (45

degrees) for cuts within slightly to moderately weathered bedrock

(depending on joint and bedding orientation)

The cut batters recommended for the bedrock above are subject to the rock being intact

and not showing adverse dip or joint orientations. A geotechnical consultant should

approve these slopes on site immediately after construction.

Where the batters recommended above are not practical due to the steep nature of the

sites, cut to fill platforms in conjunction with retaining walls may be necessary to

facilitate development. To this end, sites with slope grades in excess of 1:5 (11

degrees)

may need to consider retaining measures.

11.2 Founding

11.2.1 Founding Conditions

The variable founding conditions, which are typically controlled largely by the

geomorphological site features, are apparent across the proposed Development. The

variety of founding conditions that may be encountered are described as different

Geotechnical Zones outlined below:

i. Geotechnical Zone 1 : Shallow Bedrock (<1m below existing ground levels).

ii. Geotechnical Zone 2 : Potentially collapsible colluvial topsoil and compressible

residual sandy clay subsoils overlying completely weathered Bedrock (Bedrock

located between 1m and 2m below existing ground levels)

iii. Geotechnical Zone 3 : Deep, slightly active, compressible residual clayey subsoils

(Bedrock located >2m below existing ground levels)

Additionally, there is also:

iv. Differential founding conditions as a result of cut to fill platforms constructed on

gently to moderately sloping portions of the site.



BALLITO.


Ref. 18/N8514

11.2.2 Founding Recommendations

The depths to suitable founding materials beneath the low strength and potentially

active, compressible clayey soils or the potentially collapsible sandy clayey soils vary

across the site. In addition, contrasting founding conditions will arise across cut and fill

terraces, usually resulting in relatively shallow founding on suitable materials over the

cut layout, stepping down and deepening significantly beneath the fill portion of the

layout.

As such, a number of founding options to address the anticipated subsoil variability

would apply across the site. Taking into account the nature of the residential

developments proposed on the estate, which is generally anticipated to range between

single storey freestanding houses and double/ multiple storey apartment blocks

(potentially sensitive to movements), it is strongly advised that foundation loads be

transferred onto competent, weathered bedrock wherever possible. Whilst it would be

advisable to geotechnically assess individual sites independently, two (2No.) possible

founding options are listed below for preliminary consideration.

11.3 Option 1: Reinforced Concrete Strip Footings (and/or Ground Beams on

Mass Concrete Pads)

The economic use of a founding solution comprising reinforced concrete strip footings is

likely to prove feasible across the site where suitable founding materials (i.e. weathered

bedrock) occur within 1m of finished platform level.

Where the approved founding materials (ie. weathered bedrock) occur at greater depths

within 1.5m to a maximum of 2m of finished platform level, the use of mass concrete

pads supporting reinforced concrete ground beams should prove more economically

advantageous.

These types of foundation are likely to be feasible within Geotechnical Zones 1 and 2.

However, due to the sloping nature of the above geotechnical zones, deeper founding is

likely to occur over fill portions of platforms. (Refer to Option 2 below for founding

solution where approved founding materials are greater than 2m below finished

platform levels).

For this founding method to provide stable founding, the following precautions are

recommended:

▫ Foundation loads must be transferred through the colluvial topsoils and residual

soils onto the weathered bedrock. It is recommended that the strip and pad footings



BALLITO.


Ref. 18/N8514

are sized according to a net allowable foundation pressure not exceeding

150kN/m2

.

▫ Where differential conditions arise due to structures straddling cut to fill terraces,

and mass concrete pads supporting ground beams are necessary, the reinforced

concrete ground beams would need to be designed to span between pad

foundations. Pad foundations should be founded 0.3m into intact bedrock.

11.4 Option 2: Reinforced Concrete Ground Beams in conjunction with

Augered Mini-Piles

Where the depth to approved founding materials typically exceeds 2m below terrace

level, auger piles socketed into the weathered bedrock could be used in place of the

above-mentioned mass concrete pads. Their use will also be dependent on the

presence of boulder within the fill which may render augering difficult.

Provisionally, this type of foundation is considered to be appropriate over the fill

portions of sites located on sloping ground and within Geotechnical Zone 3.

The number, spacing and length of piles will obviously vary depending on the grading

scheme of the site, the variance in subsoil materials and the nature of the structure.

Accordingly, individual developments should be assessed separately.

12. PROPOSED RESERVOIR SITE

The near-surface conditions at the site of the proposed Reservoir can be inferred from

Inspection Pit IP Res1. The subsoil material typically comprises a colluvial horizon

described as, dry to slightly moist, dark grey, very loose to loose, moderately clayey

SAND to a depth of approximately 0.8m below existing ground level. These colluvial

subsoils are underlain by residual clays typically described as, slightly moist, reddish

orange brown, very stiff, sandy CLAY extending to depths of approximately 1.4m

below existing ground level. Underlying the abovementioned subsoil sequences,

(W5/W4) medium yellowish orange brown, completely to highly weathered, no visible

jointing, very soft to soft rock, fine to medium grained SANDSTONE (Natal Group) was

encountered at a depth of 1.4m below existing ground level.

Accordingly, founding of the Reservoir should be located into the intact albeit highly

weathered Sandstone at a depth of approximately 1,8m below existing ground levels.



BALLITO.


Ref. 18/N8514

13. PROPOSED WATER TREATMENT WORKS SITE

The sub-surface conditions at the site of the proposed Waste Water Treatment Works

can be inferred from Inspection Pit IP WWTW1. As the WWTW is located on a lower

topographic elevation, the subsoil material typically comprises colluvial / alluvial sub-

soils described as, moist, medium grey, very loose to loose, voided, moderately clayey

SAND to depths of approximately 0.9m below existing ground level. These colluvial /

alluvial subsoils are in turn underlain by residual Sandstone clays typically described as,

moist to wet, medium grey blotched orange brown, soft to very stiff, intact, SANDY

CLAY extending to depths greater than approximately 3m below existing ground levels.

The final design of the Waste Water Treatment Works was not confirmed at the time of

writing this report, however it is anticipated to comprise a Packaged Treatment Plant

with the foundations anticipated to comprise a combination of shallow conventional

strip footings, reinforced raft foundations, to deeper subsurface structures likely to be

founded to depths of approximately 3,5m below existing ground levels.

It is recommended that ground improvement measures be undertaken beneath all the

proposed shallow founded Structures located in the Alluvial/Residual subsoils, as

detailed below:

Depending on the final platform level selected, it is recommended that the, proposed

shallow founded structures be located on an engineered soil raft in order to restrict

potential total and differential settlements that may arise across the structure.

It is recommended that the soils beneath the plan area of the structure and 1m beyond

the periphery be boxed-out to a depth of 1.5m below underside of foundations and

replaced with an inert granular material, of at least a G5 material classification.

The G5 material should be replaced in 200mm thick layers and compacted to achieve

98% Modified AASHTO maximum dry density. Compaction of the layers should

proceed to underside foundation level.

It is essential that strict quality control is exercised on compaction of the engineered fill

material. In this regard allowance for regular sampling and testing should be made in

the tender.

Provided the above measures are properly implemented angular distortion of the

structure arising from differential settlement should not exceed 1 : 500.



BALLITO.


Ref. 18/N8514

Dewatering and subsoil drainage would most likely be required at depths greater than

approximately 1.5m depth, based on Inspection Pit IP WWTW 1.

14. ROADS

14.1 Road Earthworks


For the excavatability characteristics of the insitu materials in terms of road earthworks,

refer to Section 9 of this report.

14.1.2 Embankment Construction

Considering the topography of the area, it is anticipated that a large portion of the road

construction will need to adopt a cut-to-fill methodology. It is therefore recommended

that all earthworks and embankment construction be carried out in accordance with the

specifications given in the current SABS 1200 documentation.

Generally, the colluvial topsoil and residual Sandstone / Tillite / Diamictite subsoils

(which classify as poorer than G10 in terms of TRH 14) are not recommended for the

use in the construction in the road embankments fill due to the potential for longterm

consolidation/settlement.

All vegetation and topsoil should be cleared from the areas over which fill is to be

placed. This material should be stockpiled for later use as topsoil and for landscaping.

In the event that fill is to be placed onto loose colluvial material, it is recommended that

the ground surface should be well compacted before commencing fill placement. Where

the natural ground slopes exceed 1:6 (approximately 9 degrees), fill should be benched

into the insitu material to promote compaction and stability.

Fill should be placed in layers not exceeding 300mm and compacted to a minimum

93% Mod. AASHTO maximum dry density. Boulders larger than 200mm should be

removed from the fill material in order to enhance compaction and reduce the risk of

piping.

Regular compaction density control tests should be undertaken during construction of

fill embankments as set down in SABS 1200 series guidelines.



BALLITO.


Ref. 18/N8514

Where slightly to moderately weathered bedrock is excavated, this material should be

broken down and stockpiled for use as rock fill in the lower layers of road embankment

fills. Boulders greater than 600mm that cannot be broken down should be screened

out, and the rock fill then placed in layers not exceeding 600mm and spread in

accordance with SABS 1200 DM criteria. It is important to ensure that the voids

inherent in these poorly sorted rock fill materials are completely choked with finer

materials during compaction.

The colluvial topsoil referred to above should be placed onto the surfaces of

embankments after construction and vegetated as soon as possible to promote stability

and limit erosion.

The following batters are recommended:

▫ 1:2 (26


▫ 1:3 (18


▫ 1:2 (26

degrees) for cuts within subsoils subject to maximum height of 2m

▫ 1:1.5 (34

degrees) for cuts within highly weathered bedrock (depending on joint

and bedding orientation)

▫ 1:1+ (45 degrees) for cuts within slightly to moderately weathered bedrock

(depending on joint and bedding orientation)

The cut batters recommended for the bedrock above are subject to the rock being intact

and not showing adverse dip or joint orientations. A geotechnical consultant should

approve these slopes on site immediately after construction.

14.2 Road Subgrade Assessment

A variation in material characteristics occurs across the proposed Development. Road

subgrade materials range from colluvial topsoils and residual sandy clayey subsoils,

which generally classify as poorer than G10 in terms of TRH 14 guidelines, to shallow

as well as intact bedrock. A more detailed description of the road subgrade materials

and their characteristics is given overleaf.

14.2.1 Subgrade

The roads and parking areas for the Development are likely to require an engineered

material depth of 600mm to 800mm below finished road level.

The potentially compressible and collapsible nature of these subsoils, as well as the poor

CBR values (providing inadequate material strength) and poor TRH 14 classification



BALLITO.


Ref. 18/N8514

(poorer than G10) indicate that these materials are unlikely to be suitable for the use as

insitu subgrade materials.

The colluvial sample selected for testing from IP 4, indicated a TRH14 classification of

G8, indicating that this material could possibly be suitable for re-use as a subgrade in

the road layer works design. However, the variation in topographical elevation and

underlying lithology could likely have an influence on the material properties of the

colluvium encountered across the site. It is therefore our recommendation, that if this

material is considered for re-use in sub-grade construction, that regular onsite testing be

undertaken to confirm the suitability of this material as the material properties could

vary considerably across the site.

Due to the generally poor subsoils encountered across the site, it is therefore

recommended that the subgrade soils are improved to provide a stable foundation for

roads and parking by:

a) removing the existing soils to a suitable depth where the majority of the in-situ

materials provide an adequate sub-grade material – e.g. in the residual weathered

sandstones – and constructing the road layerworks thereon. (This would apply

typically where the vertical road alignment results in cuts of greater than 1,5 to 2m).

Once the road and parking alignments have been finalised and bulk excavations done,

the project Civil Engineer should assess the most economical option of subgrade

improvement vs pavement design. It is also further recommended that additional

confirmatory laboratory testing is undertaken on the subsoils encountered across the

site at the commencement of construction.

14.2.2 Layerworks

As indicated in Section 8, the TRH 14 classification of the insitu materials on site are

typically poorer than G10. Accordingly, these natural materials are unsuitable for use in

sub-base (lower) layers of road layerworks.

It is recommended that suitably inert, imported gravels are used in all layerworks on the

site.

14.2.3 General

Once bulk excavations have been done for the roads and parking areas it may be

necessary to conduct limited, specific assessment of exposed soils – particularly in



BALLITO.


Ref. 18/N8514

drainage lines, or where groundwater is evidenced – to determine subgrade conditions

and a need for “pioneer” layers.

14.3 Subsoil Drainage

It is anticipated that localized seepage activity could develop intermittently within road

cuttings subsequent to road construction. Seepages of this nature can cause minor

erosion of soils and / or localized instability within the bedrock with unfavourable

discontinuity orientations. The requirements for subsoil (for example, herringbone)

drains within such cuttings should be established in consultation with the geotechnical

consultant during construction.

15. ENGINEERING SERVICES

15.1 Earthworks


For the excavatability characteristics of the insitu materials in terms of trenching for

engineering services, refer to Section 9 of this report.

15.1.2 Backfill Material Assessment

Water, electricity and other services are anticipated to run largely within the road

reserves at the proposed Development. However, water borne sewerage is anticipated

to be collected from each unit and fed into the proposed Water Treatment Works.

With regard to the above, a brief assessment of the insitu backfill materials in terms of

pipe trenching is given below.

No material considered suitable in terms of SABS 1200 LB criteria for use as bedding

material, selected gravel or selected fill within pipe trenches was observed on site during

the preliminary geotechnical investigation. As such, provision should be made for

importing bedding sands, selected gravels and selected fill for this purpose.

In terms of SABS 1200 D criteria, the insitu subsoils present across the site are generally

suitable for use as backfill for closing pipe trenches. Notwithstanding this, the following

precautions are advised:

▫ Residual clays should not be used for backfill.



BALLITO.


Ref. 18/N8514

▫ The top 500mm topsoil should be removed and stockpiled for use on

embankments.

▫ Wet, highly fissured materials and boulders or clods greater than 100mm in size

should be screened out.

▫ The placement of the fill should be in layers not exceeding 200mm, individually

compacted at optimum moisture content to 90% Mod. AASHTO maximum dry

density.

-------oo0oo-------

APPENDIX 1

Inspection Pit Logs and DCP Test Results

PROJECT: Geotechnical Investigation for Helmsley MACHINE: Volvo BL61B INSPECTION PIT NO.

Residential Country Estate Development I.P. 1

DATE: 25-26/09/2018

LOCATION: Compensation ELEVATION:LOGGED BY: N. Tonkin

DCP EQV.

Blows/100mm CBR.

2 4

2 4

2 4

1 1

0,5 1 1

1 1

1 1

1 1

1 1

1,0 15 36

15 36

31 50

41 50 1.3m

R

1,5

2,0

2,5 2.5m

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10

TO 2 4 6 8 10 + WATER TABLE -

REFUSAL -

The equivalent CBR values above are provided as an indication only.

REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist to moist, dark grey brown, very loose to loose becoming dense, voided,

moderately clayey silty SAND with abundant hard rock Sandstone boulders at base.

(Colluvium)

(W6/W5) Pale yellowish to medium brown blotched light grey, completely weathered, no

visible jointing, residual to extremely soft rock SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

3 6

2 4

1 1

0,5 1 1

1 1

1 1

2 4

1 1

1,0 3 6

6 12

5 10

7 15

11 25

1,5 5 10 1.5m

6 12

7 15

17 41

16 39

2,0 12 27

15 36

25 50

32 50

40 50

2,5 R

3,0 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist to moist, dark grey brown, very loose to dense, voided, moderately clayey silty

SAND. (Colluvium)

(W6/W5) Pale yellowish orange brown speckled light grey, completely weathered, no visible

jointing, residual to extremely soft rock, fine to medium grained SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

4 8

3 6

4 8

3 6

0,5 3 6

3 6

2 4

1 1

2 4

1,0 4 8

5 10

4 8

4 8 1.3m

5 10

1,5 4 8

5 10

6 12

4 8

5 10

2,0

2,5

2.6m

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Dry to slightly moist, dark grey brown, very loose to loose, voided, moderately clayey silty

SAND with abundant gravel at base (pebble marker). (Colluvium)

(W6/W5) pale yellowish orange brown speckled light grey, completely weathered, no visible

jointing, extremely soft rock SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

3 6

2 4

2 4

2 4

0,5 2 4

2 4 0.60m

2 4

2 4

2 4

1,0 5 10

4 8

6 12

4 8 1.30m

4 8

1,5 3 6

4 8

4 8

8 17

6 12

2,0 6 12

6 12

14 32

11 25

7 15

2,5 12 27

24 50

16 39

16 39

28 50 2.9m

3,0 31 50

3.1m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, loose, voided, moderately clayey silty SAND. (Colluvium)

Moist, reddish orange brown, soft to stiff, intact, SANDY CLAY (Laterite).

Moist, pale orange to yellowish brown blotched light grey, firm to very stiff, intact, SANDY

CLAY. (Residual Sandstone)

(W6) Yellowish brown blotched light grey, residual to completely weathered, no visible

jointing, residual to extremely soft rock SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

1 1

2 4

0,5 2 4

0 <1

1 1

1 1

1 1 0.9m

1,0 2 4

4 8

3 6

3 6

3 6

1,5 2 4

2 4

15 36

20 50

28 50

2,0 31 50 2.0m

36 50

41 50

R

2,5

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very loose, voided, moderately clayey, silty SAND.

(Colluvium)

(W6/W5) Pale orange brown speckled light grey, completely weathered, no visible jointing,

extremely soft rock, medium grained SANDSTONE (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

4 8

2 4

5 10

4 8

0,5 1 1

3 6

4 8

3 6 0.8m

6 12

1,0 20 50

28 50

31 50

41 50

R

1,5

2,0 2.0m

2,5

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very loose to loose, voided, moderately clayey silty SAND

with occasional Sandstone boulders. (Colluvium)

(W6/W5) medium orange to yellowish brown speckled light grey, completely weathered, no

visible jointing, extremely soft rock SANDSTONE, becoming W5/W4 with depth. (Natal

Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

1 1

1 1

1 1

2 4

0,5 4 8

3 6

4 8 0.7m

4 8

10 22

1,0 13 30

19 47

24 50

36 50

41 50

1,5 R

2,0 2.0m

2,5

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very soft to firm, shattered, SANDY CLAY. (Colluvium)

(W5/W4) pale olive brown blotched dark grey, completely to highly weathered, very highly

jointed to fractured, very soft rock Dyka Tillite with occasional hard rock corestone boulders.

(Dwyka Tillite)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

1 1

2 4

2 4

2 4

0,5 2 4

1 1

3 6

2 4

1 1 0.9m

1,0 4 8

4 8

2 4

2 4

2 4

1,5 5 10

6 12

3 6

3 6

6 12

2,0 12 27

12 27

12 27 2.2m

16 39

26 50

2,5 22 50

25 50

28 50

31 50

36 50

3,0 38 50 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)


with occasional Sandstone boulders (Colluvium).

Slightly moist to moist, pale yellowish orange brown, loose to medium dense, intact,

moderately clayey silty, fine to medium grained SAND. (Residual Sandstone)

(W6/W5) pale orange brown blotched speckled light grey, completely weathered, no visible

jointing, residual to extremely soft Residual SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

2 4

1 1

0,5 2 4

1 1

2 4

4 8

2 4

1,0 2 4 1.0m

2 4

3 6

5 10

9 20

1,5 12 27

9 20

8 17

7 15 1.8m

18 44

2,0 17 41

17 41

17 41

17 41

20 50

2,5 24 50

28 50

31 50

32 50

38 50

3,0 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very loose to loose, voided, moderately clayey silty SAND.

(Colluvium)

Moist, yellowish orange brown, loose to medium dense, intact, moderately clayey silty SAND.

(Residual Sandstone)

(W6/W5) yellowish brown speckled light grey, completely weathered, no visible jointing,

extremely soft rock, fine to medium grained SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

3 6

3 6

0,5 2 4

1 1

1 1

1 1

1 1

1,0 2 4 1.0m

2 4

2 4

3 6

5 10

1,5 6 12

8 17

13 30

27 50

31 50

2,0 36 50 2.0m

41 50

R

2,5

2.5m

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist to moist, dark grey brown, very loose to loose, voided, moderate clayey silty

SAND. (Colluvium)

Moist, pale yellowish brown blotched orange brown and light grey, soft to very stiff, intact,

SANDY CLAY. (Residual Sandstone)

(W5/W4) yellowish brown blotched light grey, completely to highly weathered, no visible

jointing, very soft rock SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

1 1

3 6

22 50

0,5 22 50

11 25 0.6m

5 10

5 10

5 10

1,0 3 6

5 10

11 25

21 50 1.3m

36 50

1,5 R

2,0 2,0m

2,5

3,0 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist to moist, dark grey brown, very soft to very stiff, shattered, SANDY CLAY

(Colluvium)

Moist, reddish orange brown blotched dark grey and yellow brown, stiff to very stiff, intact,

sandy silty CLAY with occasional ferricrete nodules and corestones (Residual Clay).

Moist, yellowish brown blotched light grey, stiff to very stiff, intact, sandy silty CLAY. (Residual

Tillite)

(W5) Pale olive brown blotched yellowish grey, completely weathered, no visible jointing,

extremely soft rock Dwyka Tillite (Dwyka Group).



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

2 4

1 1

0,5 3 6

2 4

5 10

6 12

3 6 0.9m

1,0 5 10

11 25

19 47

14 32

14 32

1,5 16 39

14 32

28 50

31 50

34 50

2,0 37 50 2,0m

41 50

R

2,5

3,0 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very loose to loose, voided, moderately clayey silty SAND.

(Colluvium)

Slightly moist, medium orange brown blotched dark grey (clay infill joints), medium dense to

very dense, intact, moderately clayey silty fine to medium grained SAND with occasional

gravel fragments. (Residual Sandstone)

(W6/W5) yellowish brown speckled and blotched light grey, completely weathered, no visible




DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

3 6

2 4

0,5 2 4

1 1 0.6m

1 1

2 4

1 1

1,0 1 1

1 1

2 4

3 6

2 4

1,5 2 4 1.5m

2 4

4 8

4 8

7 15

2,0 4 8 2.0m

4 8

6 12

6 12

3 6

2,5 2 4

7 15

19 47

18 44

21 50

3,0 23 50 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, reddish brown, very loose to loose, voided, moderately clayey silty SAND.

(Colluvium)

Moist, reddish orange brown, very soft to firm, intact, sandy silty CLAY. (Laterite)

(W6) medium yellowish orange brown, residual to completely weathered, no visible jointing,

residual to extremely soft rock SANDSTONE. (Natal Group)

(W5) Yellowish brown speckled light grey, completely weathered, no visible jointing, extremely

soft to very soft rock, fine to medium grained SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

3 6

3 6

0,5 5 10

9 20 0.6m

13 30

13 30

16 39

1,0 18 44

13 30

14 32

12 27

11 25

1,5 9 20

6 12

8 17 1.7m

14 32

11 25

2,0 17 41

21 50

36 50

R

2,5 2.5m

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, reddish brown, loose to medium dense, voided, moderately clayey silty SAND.

(Colluvium)

Moist, reddish orange brown, stiff to very stiff, intact, sandy silty CLAY. (Residual Sandstone)

(W5/W4) yellowish brown blotched light grey, completely to highly weathered, no visible

jointing, soft rock, medium to coarse grained SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

5 10

8 17

7 15

10 22

0,5 17 41

15 36

17 41 0.7m

14 32

15 36

1,0 11 25

11 25

12 27

13 30

13 30

1,5 13 30

9 20 1.6m

12 27

11 25

21 50

2,0 41 50

R

2,5 2.5m

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, reddish brown, loose to dense, voided, moderately clayey silty SAND with

abundant rootlets. (Colluvium)

Moist, reddish orange brown, very stiff, intact, sandy CLAY. (Residual Sandstone)

(W5/W4) Pale yellowish orange brown speckled light grey, completely to highly weathered, no

visible jointing, very soft to soft rock, medium to coarse grained SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

3 6

2 4 0.3m

8 17

0,5 4 8

3 6 0.6m

3 6

4 8

10 22

1,0 17 41

22 50

17 41

13 30

24 50

1,5 28 50

37 50 1.6m

41 50

R

2,0

2,5

3,0 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

(W5) yellowish brown, completely weathered, no visible jointing, extremely soft rock, fine to

medium grained SANDSTONE. (Natal Group)

Slightly moist, medium to dark brown, very loose to loose, voided, moderately clayey silty

SAND (Colluvium)

Moist, reddish brown, firm to stiff, intact, SANDY CLAY with abundant gravel fragments.

(Residual Sandstone).

Moist, reddish orange brown speckled yellowish brown, medium dense, intact, moderately

clayey silty SAND. (Residual Sandstone)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

2 4

2 4

2 4

2 4

0,5 2 4 0.5m

2 4

10 22

11 25

9 20

1,0 9 20

14 32

16 39

19 47

18 44

1,5 13 30

13 30

16 39

19 47

16 39 1.9m

2,0 32 50

41 50

R

2,5

3,0

3.2m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, soft, shattered, SANDY CLAY. (Colluvium)

Moist, reddish orange brown, medium dense to dense, intact, moderately clayey silty SAND

with dark grey brown clay infill joints. (Residual Sandstone)

(W6/W5) Yellowish orange brown speckled light grey, completely weathered, no visible




DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

3 6

3 6

3 6

2 4

0,5 3 6

3 6 0.6m

5 10

7 15

10 22

1,0 13 30

9 20

9 20

10 22

13 30

1,5 12 27

11 25

11 25

8 17

7 15

2,0 6 12

5 10

7 15

5 10 2.3m

7 15

2,5 10 22

9 20

12 27

18 44

26 50

3,0 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

(W6/W5) yellowish brown speckled light grey, completely weathered, no visible jointing,

extremely soft rock SANDSTONE. (Natal Group)


(Colluvium).

Moist, yellowish orange brown, loose to medium dense, intact, moderately clayey, silty fine to

medium grained SAND with dark grey clay infill joints (Residual Sandstone)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

3 6

2 4

2 4

2 4 0.4m

0,5 2 4

5 10

5 10

4 8

3 6

1,0 3 6

4 8

8 17

11 25

11 25 1.4m

1,5 15 36

19 47

20 50

20 50

14 32

2,0 20 50

24 50

28 50

36 50

40 50

2,5 R 2.5m

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, soft to firm, shattered, SANDY CLAY (Colluvium)

Moist, dark reddish brown, firm to very stiff, intact, sandy CLAY. (Laterite)

(W6/W5) yellowish blotched orange brown, completely weathered, no visible jointing,

extremely to very soft rock, fine to medium grained SANDSTONE. (Natal Group)



DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

3 6

2 4

1 1

3 6

0,5 2 4

4 8

4 8

6 12 0.8m

4 8

1,0 5 10

7 15

8 17

9 20

9 20

1,5 10 22

13 30

14 32

12 27

15 36

2,0 13 30

13 30

10 22

12 27 2.3m

16 39

2,5 22 50

24 50

27 50

31 50

40 50

3,0 R 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very soft to stiff, shattered, SANDY CLAY (Colluvium).

Moist, orange brown blotched dak grey brown, shattered, firm to very stiff, intact SANDY

CLAY. (Residual Sandstone)

(W6/W5) yellowish brown blotched orange brown and speckled light grey, completely

weathered, no visible jointing, extremely soft to very soft rock, fine to medium grained

SANDSTONE. (Natal Group)


Residential Country Estate Development I.P. WT W1

DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

1 1

1 1

2 4

2 4

0,5 2 4

1 1

0 <1

0 <1

3 6 0.9m

1,0 1 1

1 1

2 4

1 1

2 4

1,5 6 12

7 15

13 30

8 17

8 17

2,0 13 30

16 39

10 22

15 36

19 47

2,5 8 17

6 12

5 10

6 12

8 17

3,0 8 17 3.0m

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Moist, medium grey, very loose to loose, voided, moderately clayey silty SAND. (Colluvium)

Medium grey, blotched orange brown, very soft to very stiff, intact, SANDY CLAY. (Residual

Sandstone)


Residential Country Estate Development I.P. RES 1

DATE: 25-26/09/2018


DCP EQV.

Blows/100mm CBR.

1 1

1 1

1 1

2 4

0,5 3 6

3 6

5 10

9 20 0.8m

10 22

1,0 11 25

16 39

16 39

14 32

21 50 1.4m

1,5 34 50

38 50

41 50

R

2,0 2.0m

2,5

3,0

3,5

4,0

4,5

5,0

FROM 0 2 4 6 8 10


REFUSAL -


REF.No.

18/N8514

FIG.No.

DEPTHDESCRIPTION

(m)

Slightly moist, dark grey brown, very loose to medium dense, voided, moderate clayey silty

SAND. (Colluvium)

Slightly moist to moist, reddish orange brown, very stiff, intact, SANDY CLAY. (Laterite)

(W5/W4) medium yellowish orange brown to pale pink speckled light grey, completely to

highly weathered, no visible jointing, very soft to soft rock, fine to medium grained

SANDSTONE. (Natal Group)

APPENDIX 2

Laboratory Test Results

DRAWINGS

18/N8514-01 – Geotechnical Site Plan

CLIENT

Bigen Africa (Pty) Ltd

PROJECT

Geotechnical Investigation for the Proposed

Helmsley Country Estate Development

TITLE

GEOTECHNICAL SITE PLAN

SCALE

N.T.S

DRAWING NO.

18/N8514-01

Rev

0

LEGEND

Approximate Inspection

Pit and DCP test Position

Geotechnical Zone 1

Geotechnical Zone 2

Geotechnical Zone 3

Phase 1

Phase 2

Phase 3

IP1 SST 1,3m

IP6 SST 0,8m

IP3 SST 1,3m

IP2 SST 1,5m

IP9 SST 1,8m

IP7 DT 0,7m

IP10 SST 2,0m

IP12 SST 2,0m

IP11 DT 2,0m

IP4 SST 2,9m

IP8 SST 2,2m

IP5 SST 0,5m

IP20 SST 2,3m

IP19 SST 1,4m

IP18 SST 2,3m IP13 SST 2,0m

IP14 SST1,7m

IP15 SST1,6m

IP16 SST 1,6m

WWTW 1 SST>3m

IP17 SST 1,8m

RES 1 SST 1,4m

Zone 1

Zone 2 Zone 3

Documents

REPORT ON THE RESULTS OF A GEOTECHNICAL SITE … · 2019. 1. 9. · PROPOSED HELMSLEY RESIDENTIAL COUNTRY ESTATE DEVELOPMENT – BALLITO. October 2018 Davies Lynn & Partners (Pty)