SOLUTION: Proposed Development: Residential dwelling

Educational use only
September 23, 201
Project No. 0001
LWI/ms
SITE INVESTIGATION REPORT
Client: Mr & Mrs Brown
Address: 1 Lake Road Toronto16:
Proposed Development: Residential dwelling
Site Description
Approx. area (m2): 698.6
Approx. fall: 1 metre to the west, reasonable site drainage
Vegetation: Grass, trees and shrubs
Improvements: 1LO
Geology, Fieldwork Details and Subsurface Conditions
The Sydney geological series sheet at a scale of 1:100,000 shows the site is underlain by
Triassic Age Ashfield Shale of the Wianamatta Group. Rocks within this formation
comprise shale and laminite.
Three boreholes were drilled and three Dynamic cone penetrometer (DCP) tests were
carried out on September 14, 201 at the locations shown on Drawing No. $.
Restricted site access dictated the borehole locations. The subsurface conditions
encountered are shown on the attached borehole logs. Explanation sheets and notes
relating to geotechnical reports are also attached.
When making an assessment of the subsurface conditions across a site from a limited
number of boreholes, there is the possibility that variations may occur between test
locations. The data derived from the site investigation programme are extrapolated across
the site to form a geological model and an engineering opinion is rendered about overall
subsurface conditions and their likely behaviour with regard to the proposed development.
The actual condition at the site may differ from those inferred, since no subsurface
exploration programme, no matter how comprehensive, can reveal all subsurface details
and anomalies.
The subsurface conditions consist of topsoil overlying silty clays and weathered shale. The
topsoil is 0.3 to 0.4 metres thick. Natural silty clays underlie the site to depths of
1.1 metres and the depth of drilling, 3.0 metres. The strength of these materials vary
between firm to stiff and very stiff. In BH1 and BH3 weathered shale was present to depths
of 1.5 and 2.0 metres. Auger refusal occurred at these depths.
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
No groundwater was observed in the boreholes during the fieldwork.
Site Classification
The classification has been prepared in accordance with the guidelines set out in the
“Residential Slabs and Footings” Code, AS2870 – 1996.
Based on the subsurface conditions observed, the site is classified highly reactive (H),
provided the recommendations given below are adopted.
Foundation Design and Construction
Pad and/or strip footings founded in natural materials below the topsoil may be
proportioned using an allowable bearing pressure of 100 kPa. The minimum depth of
founding must comply with the requirements of AS2870
If a higher load carrying capacity is required, piers should be used to transfer the loads to
the underlying stronger materials. Footings or piers founded in the weathered shale may be
proportioned using an allowable end bearing pressure of 700 kPa. An adhesion value of
70 kPa applies to the portion of the shaft within the weathered rock.
In order to ensure the bearing values given can be achieved, care should be taken to ensure
the base of the excavations are free of all loose material prior to concreting. To this end, it
is recommended that all excavations be concreted as soon as possible, preferably
immediately after excavating, cleaning, inspecting and approval. Pier excavations should
not be left open overnight. The possibility of groundwater inflow needs to be considered
when drilling the piers and pouring concrete.
The site is considered suitable for slab on ground construction provided due regard is given
to the groundsurface slope.
During foundation construction, should the subsurface conditions vary to those inferred in
this report, a suitably experienced geotechnical engineer should review the design and
recommendations given above to determine if any alterations are required.
Additional Comments
Attention is drawn to Appendix B of AS2870 – 1996 regarding the need to properly
maintain the foundations. Surface drainage should be provided to avoid the possibility of
water ponding near the building and the finished ground surface should fall at least 50 mm
over a distance of one metre away from the building.
The above classification has been made assuming that the maximum depth to filling placed
in any building platform will be 400 mm and that all footings will bear in either natural
ground or in control filling. Prior to the placement of any filling the existing surface
should be stripped of all vegetation and topsoil.
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
The above classification is based on the soil profiles observed at the time of testing. If site
works are undertaken, the classification of the actual building platform may vary across the
site depending upon the extent of the cut and/or fill and the degree of compaction of any
fill. The designer of the footing system must take the above factors into account.
If excavations for rainwater or detention tanks are to be made within 6 metres of the
building foundations, advice should be sought regarding their effect on the foundations.
Placing absorption trenches on the high side of the property may create abnormal moisture
conditions for the foundations (Refer to Section 1.3.3 of AS2870). This could have a
negative effect on the foundation performance and more than likely alter the site
classification provided above.
This report has been prepared assuming the site development will be limited to one or two
storey residential buildings. The information and interpretation may not be relevant if the
design proposal changes (e.g. to a five-storey building involving major cuts during the site
preparation). If changes occur, we would be pleased to review the report and advise on the
adequacy of the investigation.
Laurie Ihnativ, BE, MEngSc, MBA, FIE Aust.
Manager, SMEC Testing Services Pty Limited
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
60(&7(67,1*6(59,&(63W/WG 6FDOH8QNQRZQ ‘DWH6HSWHPEHU8
Client: MR & MRS BROWN
6,7(,19(67,*$7,21
1 LAKE ROAD TORONTO NSW2283
%25(+2/($1’3(1(7520(7(5/2&$7,216
3URMHFW1R
0001
‘UDZLQJ1RA03
BH3P3
BH2P2
BH1P1
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty
Ltd. Certain details have been changed and redacted to protect private and confidential information. TAFE NSW has
been granted use of the report solely for educational purposes and any person who receives a copy of this report (or
any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report
for any other purpose whatsoever. The author does not accept a duty of care or any other legal responsibility in
relation to this report.
Educational use only
NOTES RELATING TO GEOTECHNICAL REPORTS
Introduction
These notes have been provided to outline the
methodology and limitations inherent in
geotechnical reporting. The issues discussed are
not relevant to all reports and further advice
should be sought if there are any queries
regarding any advice or report.
When copies of reports are made, they should be
reproduced in full.
Geotechnical Reports
Geotechnical reports are prepared by qualified
personnel on the information supplied or
obtained and are based on current engineering
standards of interpretation and analysis.
Information may be gained from limited
subsurface testing, surface observations, previous
work and is supplemented by knowledge of the
local geology and experience of the range of
properties that may be exhibited by the materials
present. For this reason, geotechnical reports
should be regarded as interpretative rather than
factual documents, limited to some extent by the
scope of information on which they rely.
Where the report has been prepared for a specific
purpose (eg. design of a three-storey building),
the information and interpretation may not be
appropriate if the design is changed (eg. a twenty
storey building). In such cases, the report and the
sufficiency of the existing work should be
reviewed by SMEC Testing Services Pty Limited
in the light of the new proposal.
Every care is taken with the report content,
however, it is not always possible to anticipate or
assume responsibility for the following
conditions:
 Unexpected variations in ground conditions.
The potential for this depends on the amount
of investigative work undertaken.
 Changes in policy or interpretation by
statutory authorities.
 The actions of contractors responding to
commercial pressures.
If these occur, SMEC Testing Services Pty
Limited would be pleased to resolve the matter
through further investigation, analysis or advice.
Unforeseen Conditions
Should conditions encountered on site differ
markedly from those anticipated from the
information contained in the report, SMEC
Testing Services Pty Limited should be notified
immediately. Early identification of site
anomalies generally results in any problems
being more readily resolved and allows reinterpretation and assessment of the implications
for future work.
Subsurface Information
Logs of a borehole, recovered core, test pit,
excavated face or cone penetration test are an
engineering and/or geological interpretation of
the subsurface conditions. The reliability of the
logged information depends on the
drilling/testing method, sampling and/or
observation spacings and the ground conditions.
It is not always possible or economic to obtain
continuous high quality data. It should also be
recognised that the volume or material observed
or tested is only a fraction of the total subsurface
profile.
Interpretation of subsurface information and
application to design and construction must take
into consideration the spacing of the test
locations, the frequency of observations and
testing, and the possibility that geological
boundaries may vary between observation points.
Groundwater observations and measurements
outside of specially designed and constructed
piezometers should be treated with care for the
following reasons:
 In low permeability soils groundwater may
not seep into an excavation or bore in the
short time it is left open.
 A localised perched water table may not
represent the true water table.
 Groundwater levels vary according to
rainfall events or season.
 Some drilling and testing procedures mask or
prevent groundwater inflow.
The installation of piezometers and long term
monitoring of groundwater levels may be
required to adequately identify groundwater
conditions.
Supply of Geotechnical Information or
Tendering Purposes
It is recommended tenderers are provided with as
much geological and geotechnical information
that is available and that where there are
uncertainties regarding the ground conditions,
prospective tenders should be provided with
comments discussing the range of likely
conditions in addition to the investigation data.
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
SMEC Testing Services Pty Ltd GEOTECHNICAL LOG – NON CORE BOREHOLE

Client: MR & MRS BROWN Project: 1 LAKE ROAD TORONTO NSW Location: Refer to Drawing No. A03 Project No.: 0001 Date : September 14, 2018 Logged: AC	BOREHOLE NO.: BH 1
Sheet 1 of 1
CONSISTENCY (cohesive soils) or RELATIVE DENSITY (sands and gravels)	M O I S T U R E	W A T T A E B R L E	S A M P L E S	S Y M B O L	DESCRIPTION OF DRILLED PRODUCT (Soil type, colour, grain size, plasticity, minor components, observations)	DEPTH (m)
SILTY CLAY: dark brown, low plasticity TOPSOIL	CL	FIRM	D-M	0.5 1.0 1.5 2.0 2.5
SILTY CLAY: brown/orange brown, medium plasticity	CL	FIRM TO STIFF	M
SILTY CLAY: light grey with orange brown, medium plasticity	CL	VERY STIFF	M
SHALE: grey	EXTREMELY LOW STRENGTH	D
AUGER REFUSAL AT 1.5 M
NOTES: D – disturbed sample U – undisturbed tube sample B – bulk sample WT – level of water table or free water N – Standard Penetration Test (SPT)	Contractor: STS Equipment: Christie Hole Diameter (mm): 100 Angle from Vertical (°) 0
See explanation sheets for meaning of all descriptive terms and symbols

AssignmentTutorOnline

This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
SMEC Testing Services Pty Ltd GEOTECHNICAL LOG – NON CORE BOREHOLE

BOREHOLE NO.: BH 2	Client: MR & MRS BROWN Project: 1 LAKE ROAD TORONTO NSW Location: Refer to Drawing No. A03 Project No.: 0001 Date : September 14, 2018 Logged: AC
Sheet 1 of 1
CONSISTENCY (cohesive soils) or RELATIVE DENSITY (sands and gravels)	M O I S T U R E	W A T T A E B R L E	S A M P L E S	S Y M B O L	DESCRIPTION OF DRILLED PRODUCT (Soil type, colour, grain size, plasticity, minor components, observations)	DEPTH (m)
SILTY CLAY: dark brown, low plasticity TOPSOIL	CL	FIRM	D-M	0.5 1.0 1.5 2.0 2.5
SILTY CLAY: orange brown, medium plasticity	CL	FIRM TO STIFF	M
SILTY CLAY: grey with orange brown, medium plasticity	CL	STIFF BECOMING VERY STIFF	M
SILTY CLAY: grey with red brown, trace to some fine gravel BOREHOLE DISCONTINUED AT 3.0 M	CL	VERY STIFF	D-M
NOTES: D – disturbed sample U – undisturbed tube sample B – bulk sample WT – level of water table or free water N – Standard Penetration Test (SPT)	Contractor: STS Equipment: Christie Hole Diameter (mm): 100 Angle from Vertical (°) 0
See explanation sheets for meaning of all descriptive terms and symbols

BOREHOLE NO.: BH 3	Client: MR & MRS BROWN Project: 1 LAKE ROAD TORONTO NSW Location: Refer to Drawing No. A03 Project No.: 0001 Date : September 14, 2018 Logged: AC
Sheet 1 of 1
CONSISTENCY (cohesive soils) or RELATIVE DENSITY (sands and gravels)	M O I S T U R E	W A T T A E B R L E	S A M P L E S	S Y M B O L	DESCRIPTION OF DRILLED PRODUCT (Soil type, colour, grain size, plasticity, minor components, observations)	DEPTH (m)
SILTY CLAY: dark brown, low plasticity TOPSOIL	CL	FIRM	D-M	0.5 1.0 1.5 2.0 2.5
SILTY CLAY: brown/orange brown, medium plasticity	CL	FIRM TO STIFF	M
SILTY CLAY: grey, medium plasticity	CL	STIFF	M
VERY STIFF
SHALE: grey	EXTREMELY LOW STRENGTH	D
AUGER REFUSAL AT 2.0 M
NOTES: D – disturbed sample U – undisturbed tube sample B – bulk sample WT – level of water table or free water N – Standard Penetration Test (SPT)	Contractor: STS Equipment: Christie Hole Diameter (mm): 100 Angle from Vertical (°) 0
See explanation sheets for meaning of all descriptive terms and symbols

SMEC Testing Services Pty Ltd 14/1 Cowpasture Place, Wetherill Park NSW 2164 Phone: (02)9756 2166 Fax: (02)9756 1137 Email: [email protected] Dynamic Cone Penetrometer Test Report Project No.: 001 Report No.: 10/2018 Report Date: 23/9/2018 Project: 1 LAKE ROAD TORONTO NSW 2283 Client: MR & MRS BROWN Address: PO BOX 001, TORONTO Test Method: AS 1289.6.3.2 Page: 1 of 1
Site No.	P1	P2	P3
Location	Refer to Drawing No. A03	Refer to Drawing No. A03	Refer to Drawing No. A03
Starting Level	Surface Level	Surface Level	Surface Level
Depth (m)	Penetration Resistance (blows / 150mm)
0.00 – 0.15	2	2	2
0.15 – 0.30	2	3	3
0.30 – 0.45	3	4	4
0.45 – 0.60	4	4	4
0.60 – 0.75	5	5	5
0.75 – 0.90	7	6	6
0.90 – 1.05	20/R	8	6
1.05 – 1.20	14	8
1.20 – 1.35	20/D	14
1.35 – 1.50	20/R
1.50 – 1.65
1.65 – 1.80
1.80 – 1.95
1.95 – 2.10
2.10 – 2.25
2.25 – 2.40
2.40 – 2.55
2.55 – 2.70
2.70 – 2.85
2.85 – 3.00
3.00 – 3.15
3.15 – 3.30
3.30 – 3.45
3.45 – 3.60
3.60 – 3.75
Remarks: * Pre drilled prior to testing Approved Signatory…………………………………………… Technician: AC Laurie Ihnativ – Manager

E1.1	Soil	Classification	and	the	Unified
System

An assessment of the site conditions usually includes an
appraisal of the data available by combining values of
engineering properties obtained by the site investigation
with descriptions, from visual observation of the materials
present on site.
The system used by SMEC in the identification of soil is
the Unified Soil Classification system (USC) which was
developed by the US Army Corps of Engineers during
World War II and has since gained international acceptance
and has been adopted in its metricated form by the
Standards Association of Australia.
The Australian Site Investigation Code (AS1726-1981,
Appendix D) recommends that the description of a soil
includes the USC group symbols which are an integral
component of the system.
The soil description should contain the following
information in order:
Soil composition
x SOIL NAME and USC classification symbol (IN
BLOCK LETTERS)
x plasticity or particle characteristics
x colour
x secondary and minor constituents (name estimated
proportion, plasticity or particle characteristics, colour
Soil condition
x moisture condition
x consistency or density index
Soil structure
x structure (zoning, defects, cementing)
Soil origin
interpretation based on observation eg FILL, TOPSOIL,
RESIDUAL, ALLUVIUM.

E1.2
(a)

Soil Composition
Soil Name and Classification
Symbol

The USC system is summarized in Figure E1.2.1. The
primary division separates soil types on the basis of particle
size into:
x Coarse grained soils – more than 50% of the
material less than 60 mm is
larger than 0.06 mm (60 μm).
x Fine grained soils – more than 50% of the material
less than 60 mm is smaller than
0.06 mm (60 μm).
Initial classification is by particle size as shown in Table
E1.2.1. Further classification of fine grained soils is based
on plasticity.
TABLE E1.2.1 – CLASSIFICATION BY PARTICLE
SIZE

NAME	SUB-DIVISION	SIZE
Clay (1)
Silt (2)	2 μm to 60 μm
Sand	Fine Medium Coarse	60 μm to 200 μm 200 μm to 600 μm 600 μm to 2 mm
Gravel (3)	Fine Medium Coarse	2 mm to 6 mm 6 mm to 20 mm 20 mm to 60 mm
Cobbles (3)	60 mm to 200 mm
Boulders (3)	> 200 mm

Where a soil contains an appropriate amount of secondary
material, the name includes each of the secondary
components (greater than 12%) in increasing order of
significance, eg sandy silty clay.
Minor components of a soil are included in the description
by means of the terms “some” and “trace” as defined in
Table E1.2.2.
TABLE E1.2.2 – MINOR SOIL COMPONENTS

TERM	DESCRIPTION	APPROXIMATE PROPORTION (%)
Trace	presence just detectable, little or no influence on soil properties	0-5
Some	presence easily detectable, little influence on soil properties	5-12

The USC group symbols should be included with each soil
description as shown in Table E1.2.3
TABLE E1.2.3 – SOIL GROUP SYMBOLS

SOIL TYPE	PREFIX
Gravel	G
Sand	S
Silt	M
Clay	C
Organic	O
Peat	Pt

The group symbols are combined with qualifiers which
indicate grading, plasticity or secondary components as
shown on Table E1.2.4
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
TABLE E1.2.4 – SOIL GROUP QUALIFIERS

SUBGROUP	SUFFIX
Well graded	W
Poorly Graded	P
Silty	M
Clayey	C
Liquid Limit	L
Liquid Limit >50% – low to medium plasticity	H

(b)	Grading
“Well graded”	Good representation of all particle sizes from the largest to the smallest. One or more intermediate sizes poorly represented One or more intermediate sizes absent
“Poorly graded”
“Gap graded”

“Uniformly graded” Essentially single size
material.
(c) Particle shape and texture
The shape and surface texture of the coarse grained
particles should be described.
Angularity may be expressed as “rounded”, “subrounded”, “sub-angular” or “angular”.
Particle form can be “equidimensional”, “flat” or
elongate”.
Surface texture can be “glassy”, “smooth”, “rough”,
pitted” or striated”.

(d)	Colour
The colour of the soil should be described in the moist
condition using simple terms such as:
Black	White	Grey	Red
Brown	Orange	Yellow	Green
Blue

These may be modified as necessary by “light” or “dark”.
Borderline colours may be described as a combination of
two colours, eg. red-brown.
For soils that contain more than one colour terms such as:
x Speckled Very small (x Mottled Irregular
x Blotched Large irregular (>75 mm dia)
x Streaked Randomly oriented streaks
(e) Minor Components
Secondary and minor components should be individually
described in a similar manner to the dominant component.

E1.3	Soil Condition
(a)	Moisture

Soil moisture condition is described as “dry”, “moist” or
“wet”.
The moisture categories are defined as:
Dry (D) – Little or no moisture evident. Soils are running.
Moist (M) – Darkened in colour with cool feel. Granular
soil particles tend to adhere. No free water evident upon
remoulding of cohesive soils.
In addition the moisture content of cohesive soils can be
estimated in relation to their liquid or plastic limit.
(b) Consistency
Estimates of the consistency of a clay or silt soil may be
made from manual examination, hand penetrometer test,
SPT results or from laboratory tests to determine undrained

shear or unconfined compressive strengths.
classification of consistency is defined in Table E1.3.1.

The

TABLE E1.3.1 – CONSISTENCY OF FINE-GRAINED
SOILS

TERM	UNCONFINED STRENGTH (kPa)	FIELD IDENTIFICATION
Very Soft		Easily penetrated by fist. Sample exudes between fingers when squeezed in the fist.
Soft	25 – 50	Easily moulded in fingers. Easily penetrated 50 mm by thumb.
Firm	50 – 100	Can be moulded by strong pressure in the fingers. Penetrated only with great effort.
Stiff	100 – 200	Cannot be moulded in fingers. Indented by thumb but penetrated only with great effort.
Very Stiff	200 – 400	Very tough. Difficult to cut with knife. Readily indented with thumb nail.
Hard	>400	Brittle, can just be scratched with thumb nail. Tends to break into fragments.

Unconfined compressive strength as derived by a hand
penetrometer can be taken as approximately double the
undrained shear strength (qu = 2 cu).
(c) Density Index
The insitu density index of granular soils can be assessed
from the results of SPT or cone penetrometer tests. Density
index should not be estimated visually.
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.
Educational use only
TABLE E1.3.2 – DENSITY OF GRANULAR SOILS

TERM	SPT N VALUE	STATIC CONE VALUE qc (MPa)	DENSITY INDEX (%)
Very Loose	0 – 3	0 – 2	0 – 15
Loose	3 – 8	2 – 5	15 – 35
Medium Dense	8 – 25	5 – 15	35 – 65
Dense	25 – 42	15 – 20	65 – 85
Very Dense	>42	>20	>85

E1.4
(a)

Soil Structure
Zoning

A sample may consist of several zones differing in colour,
grain size or other properties. Terms to classify these zones
are:
Layer – continuous across exposure or sample
Lens – discontinuous with lenticular shape
Pocket – irregular inclusion
Each zone should be described, their distinguishing
features, and the nature of the interzone boundaries.

(b)	Defects
Defects which are present in the sample can include:
x	fissures

x roots (containing organic matter)
x tubes (hollow)
x casts (infilled)
Defects should be described giving details of dimensions
and frequency. Fissure orientation, planarity, surface
condition and infilling should be noted. If there is a
tendency to break into blocks, block dimensions should be
recorded
E1.5 Soil Origin
Information which may be interpretative but which may
contribute to the usefulness of the material description
should be included. The most common interpreted feature
is the origin of the soil. The assessment of the probable
origin is based on the soil material description, soil
structure and its relationship to other soil and rock
materials.
Common terms used are:
“Residual Soil” – Material which appears to have been
derived by weathering from the underlying rock. There is
no evidence of transport.
“Colluvium” – Material which appears to have been
transported from its original location. The method of
movement is usually the combination of gravity and
erosion.
“Landslide Debris” – An extreme form of colluvium where
the soil has been transported by mass movement. The
material is obviously distributed and contains distinct
defects related to the slope failure.
“Alluvium” – Material which has been transported
essentially by water. Usually associated with former
stream activity.
“Fill” – Material which has been transported and placed by
man. This can range from natural soils which have been
placed in a controlled manner in engineering construction
to dumped waste material. A description of the
constituents should include an assessment of the method of
placement.
E1.6 Fine Grained Soils
The physical properties of fine grained soils are dominated
by silts and clays.
The definition of clay and silt soils is governed by their
Atterberg Limits. Clay soils are characterised by the
properties of cohesion and plasticity with cohesion defines
as the ability to deform without rupture. Silts exhibit
cohesion but have low plasticity or are non-plastic.
The field characteristics of clay soils include:
x dry lumps have appreciable dry strength and cannot be
powdered
x volume changes occur with moisture content variation
x feels smooth when moist with a greasy appearance
when cut.
The field characteristics of silt soils include:
x dry lumps have negligible dry strength and can be
powdered easily
x dilatancy – an increase in volume due to shearing – is
indicted by the presence of a shiny film of water after a
hand sample is shaken. The water disappears upon
remoulding. Very fine grained sands may also exhibit
dilatancy.
x low plasticity index
x feels gritty to the teeth
E1.7 Organic Soils
Organic soils are distinguished from other soils by their
appreciable content of vegetable matter, usually derived
from plant remains.
The soil usually has a distinctive smell and low bulk
density.
The USC system uses the symbol Pt for partly decomposed
organic material. The O symbol is combined with suffixes
“O” or “H” depending on plasticity.
Where roots or root fibres are present their frequency and
the depth to which they are encountered should be
recorded. The presence of roots or root fibres does not
necessarily mean the material is an “organic material” by
classification.
Coal and lignite should be described as such and not
simply as organic matter.
This document is an amended version of an original report prepared in 2010 for a client of SMEC Testing Services Pty Ltd. Certain details have been changed and
redacted to protect private and confidential information. TAFE NSW has been granted use of the report solely for educational purposes and any person who receives a
copy of this report (or any part of it) does so on the basis that he or she acknowledges and accepts that they may not rely on or use this report for any other purpose
whatsoever. The author does not accept a duty of care or any other legal responsibility in relation to this report.