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NOOSA COUNCIL
REFERENCE DOCUMENT
MCU25/0091
Geotechnical Investigation & Stability Assessment
Proposed Cabins
224 Moran Group Road, Kin Kin
Prepared for:
Wingara Hills Pty Ltd
Email: [email protected]
Report Number: J002915-001-R-Rev0
August 2025
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
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Full text of sections 2 to 42 (of 52)
Section 2
Wingara Hills Pty Ltd
Table of Contents
1.0 INTRODUCTION ...................................................................................................................... 1
2.0 PROPOSED DEVELOPMENT ................................................................................................. 1
3.0 SITE DESCRIPTION ................................................................................................................ 1
4.0 METHOD OF INVESTIGATION ............................................................................................... 3
4.1 Walkover Survey and Subsurface Investigation ....................................................................... 3
4.2 Fieldwork .................................................................................................................................. 3
4.3 Geotechnical laboratory testing ................................................................................................ 4
5.0 RESULTS OF INVESTIGATION .............................................................................................. 4
5.1 Published Geological Information ............................................................................................. 4
5.2 Subsurface conditions .............................................................................................................. 5
5.3 Topography ............................................................................................................................... 5
5.4 Surface Drainage ...................................................................................................................... 6
5.5 Vegetation ................................................................................................................................. 6
5.6 Buildings, Other Structures, etc. ............................................................................................... 6
6.0 ASSESSMENT OF LAND STABILITY ..................................................................................... 6
6.1 Existing Conditions ................................................................................................................... 6
6.2 Stability Risk Assessment ........................................................................................................ 7
7.0 DEVELOPMENT IMPACTS & MITIGATION MEASURES....................................................... 8
7.1 Earthworks ................................................................................................................................ 8
7.1.1 Site Preparation & Trafficability ................................................................................................ 8
7.1.2 Excavations .............................................................................................................................. 8
7.1.3 Batter Slopes ............................................................................................................................ 8
7.1.4 Erosion Protection .................................................................................................................... 9
7.2 Retaining Structures ................................................................................................................. 9
7.3 Footings .................................................................................................................................... 9
7.3.1 Site Classification ................................................................................................................... 10
7.3.2 High Level Footings and Piers ................................................................................................ 10
7.4 Drainage ................................................................................................................................. 11
7.5 General Foundation Maintenance .......................................................................................... 11
8.0 WASTEWATER TREATMENT AND DISPOSAL ................................................................... 12
8.1 Wastewater Flow Design Allowance ...................................................................................... 12
8.2 Terrain-Soil Assessment ........................................................................................................ 12
8.3 Recommendations .................................................................................................................. 12
8.3.1 System Construction............................................................................................................... 13
9.0 SUMMARY AND CONCLUSIONS ......................................................................................... 14
10.0 LIMITATIONS ......................................................................................................................... 14
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Wingara Hills Pty Ltd
Tables
Table 1: Stability Risk Levels 7
Table 2: Qualitative Risk Assessment for Property (Based on AGS 2007). 7
Table 3: Retaining structure design parameters. 9
Table 4: Horizontal separation distances for irrigation areas 13
Figures
Figure 1 – Site Plan
Appendices
Appendix A Reports of Test Pits and Explanatory Notes
Appendix B Insitu Permeability Test Results
Appendix C Qualitative Risk Analysis Matrix (Australian Geomechanics Vol 42 No 1 March 2007)
Appendix D General Guidelines for Hillside Development
Appendix E CSIRO Foundation Maintenance Guidelines
Appendix F Limitations
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Section 4
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1.0 INTRODUCTION
This report presents the results of a geotechnical investigation carried out by Core Consultants Pty Ltd
(Core) for a proposed development (cabins) at 224 Moran Group Road, Kin Kin.
Our report includes a slope stability risk assessment, along with geotechnical recommendations on footing
design, earthworks, pavements, drainage and effluent disposal.
This report format generally follows the recommended Noosa Council (NC) format for geotechnical and slope
stability assessments.
2.0 PROPOSED DEVELOPMENT
We understand the client proposes to construct two single story cabins close to or at a knoll located at the
southern end of the lot (refer Image 1 below). No details of the cabins have been provided; however, we
anticipate that the cabins are to be constructed of lightweight materials. It is also anticipated that the
proposed development will require some minor earthworks including excavation for infrastructure and
services.
The cabins will be connected to an on-site treatment plant(s) with treated wastewater to be disposed of on-
site (refer Image 1 below).
Image 1: Locations of proposed cabins (Linea Design & Drafting Sheet 01, Job No. 2025550)
3.0 SITE DESCRIPTION
The site is located at 224 Moran Group Road, Kin Kin (Lot 1 on SP313593), and the total area of the lot is
approximately 101.5 ha. The site of the proposed cabins comprises a well grassed knoll bound by dense
vegetation (trees) to the north and Moran Group Road to the south. An existing residence and outbuildings,
and a dam, are located to the west (refer Image 2 below).
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Image 2: Proposed development area (NC on-line Interactive Mapping website)
General site conditions at the time of our investigation are shown on Photographs 1 and 2.
Photograph 1: Proposed cabin locations (top of knoll facing south-west).
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Photograph 2: Base of southern side of the knoll location of TP5 (facing west)
4.0 METHOD OF INVESTIGATION
As part of our investigation, a desktop study was carried out comprising a review of the published geological
maps of the area, the NC landslide hazard (susceptibility) maps and historical aerial imagery. This was
followed by a site walkover and subsurface investigation.
4.1 Walkover Survey and Subsurface Investigation
Following the desktop study, a walkover survey was conducted to assess the ground conditions and to make
an appraisal of the general condition of the site.
The walkover survey was carried out by an engineering geologist on 29 July 2025.
The walkover survey included assessment of topography, drainage, vegetation cover, geology, erosion, and
slope stability. Results of the walkover survey are discussed in Section 5.0.
4.2 Fieldwork
The investigation fieldwork was undertaken on 29 July 2025 comprising five test pits (designated TP1 to
TP5). Three test pits (TP1 to TP3) were excavated in the area of the proposed cabins. Test pits TP4 and
TP5 were located in areas initially considered for effluent disposal fields.
Test pits were excavated with a 4.5 tonne excavator, fitted with a 0.7 m toothed bucket to depths of up to 3
m below ground level (BGL). Dynamic Cone Penetrometer (DCP) tests were also carried out adjacent to the
test pits to assess soil strength.
The fieldwork was carried out in the presence of a geotechnical engineer from Core, who logged the
subsurface conditions in accordance with Australian Standard AS1726-2017 Geotechnical site
investigations.
Test locations were recorded in the field using a handheld GPS unit. Investigation locations are shown on
the attached Figure 1.
Reports of Test Pits are attached in Appendix A, together with explanatory notes. Subsurface conditions are
discussed in Section 5.2.
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In addition to the above, two Talsma Hallam constant head permeability tests were carried out at possible
locations that could be utilised for treated effluent disposal (land application). The results of those tests are
provided in Appendix B, and results are discussed in Section 8.
4.3 Geotechnical laboratory testing
Due to the timeframe required for report completion, geotechnical laboratory testing had not been
undertaken at this stage.
5.0 RESULTS OF INVESTIGATION
5.1 Published Geological Information
Published geological information 1 indicates that the site is underlain by Middle Triassic aged Kin Kin Beds
(Rk) comprising “Strongly cleaved and commonly kinked mudstone with thin siltstone laminae; minor
volcanilithic sandstone”. To the south of Moran Group Road, mapping indicates younger Quaternary age
(Qa) “Clay, silt, sand and gravel; flood-plain alluvium”.
A north-west to south-east trending fault line is shown on the mapping (dashed black line), which brings the
Late Triassic – Early Triassic age Myrtle Creek Sandstone (RJdm) formation of “Quartzose sandstone,
orthoquartzite, sublabile to labile sandstone, siltstone, shale” into contact with the Kin Kin Beds.
An extract from the geology mapping is provided in Image 3 below.
RJdm
Rk
Qa
Image 3 – Extract from Geology Map1
1
Queensland Geotechnical Database
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5.2 Subsurface conditions
The general subsurface profile encountered in test pits TP1 to TP3 comprised:
Topsoil: 0.2 m to 0.3 m of firm to stiff clay; overlying
Residual Soils: comprising low to medium plasticity, stiff to very stiff silty clay to depths ranging from
1.0 m to 1.1 m BGL at TP1 and TP2, and 3 m BGL at TP3; grading into
Extremely Weathered Material (Mudstone): comprising very stiff to hard, medium plasticity silty clay;
interbedded with
Mudstone: very low to low strength mudstone below a depth of 1.8 m to 2.7m BGL. Bands of higher
strength mudstone were encountered at TP1 only requiring ripper tyne excavation.
Test pits were completed at locations as shown on Figure 1.
5.3 Topography
The subject site is situated on knoll at the western end of a ridge running south-west down from a higher
knoll and ridge located to the east of the site. The ground slopes at about 15° to 20° on the northern and
southern sides of the knoll, and about 10° following the general ridge direction to the west. Site slopes were
measured using a handheld clinometer and are shown on Figure 1.
A defined gully line is to the north of the knoll that appears to feed into dams located to the east and west of
the residence. A less defined gully is located along the southern side of the knoll, which appears to capture
and drain less water than the northern gully.
Image 4: Site contours (1m intervals) (courtesy Queenland Globe on-line mapping tool)
Areas outside of the general area surrounding the proposed development footprint were not assessed.
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5.4 Surface Drainage
Surface drainage at the knoll and on the flanks of the knoll is considered to be good, with runoff generally
being directed downslope to the natural drainage lines (gullies) towards the north and south. The northern
gully drains into existing dams near the residence.
The ground at the base of the southern gully (near Moran Group Road) was noted to be wet at the time of
the investigation, although surface water was not noted to be flowing.
5.5 Vegetation
The area surrounding the proposed development contained some mature trees up to approximately 15 m
height. Most smaller trees and shrubs appeared to have been cleared to facilitate historical grazing in the
area although some steep sided gullies and other isolated areas contained more dense undergrowth.
At the time of our investigation, no significant signs of tilting were observed in the existing vegetation, which
can be an indicator of ground movement.
5.6 Buildings, Other Structures, etc.
No structures were located in the area of the proposed cabins. An existing residence and sheds were
located to the northwest of the cabins site, at the foot of the knoll.
6.0 ASSESSMENT OF LAND STABILITY
6.1 Existing Conditions
The NC Landslide Hazard (susceptibility) mapping indicates that the site for the proposed development is of
mostly Moderate Landslide Hazard (ref. Image 5).
Approx. proposed cabins location
Image 5: Landslide Hazard Risk Mapping
The NC Landslide Hazard Map is a broad-scale indication of potential landslide likelihood. The landslide
ratings can be superseded once site specific investigation and analysis are undertaken (i.e. this report).
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6.2 Stability Risk Assessment
A qualitative slope stability risk assessment has been carried out following the Australian Geomechanics
Society (AGS) Guidelines for Landslide Risk Management (March 2007). The risk assessment relates to
property and potential development. Relative levels of risk and their implications are given in Table 2 below
and the qualitative terminology (i.e. likelihood and consequence definitions) for use in assessing risk to
property are attached in Appendix C.
Table 1: Stability Risk Levels
Risk Level Example Implications(1)
Unacceptable without treatment. Extensive detailed investigation and research,
VERY HIGH planning and implementation of treatment options essential to reduce risk to
VH
RISK Low; may be too expensive and not practical. Work likely to cost more than
value of property.
Unacceptable without treatment. Detailed investigation, planning and
H HIGH RISK implementation of treatment options required to reduce risk to Low. Work would
cost a substantial sum in relation to the value of the property.
May be tolerated in certain circumstances (subject to regulators’ approval) but
MODERATE requires investigation, planning and implementation of treatment options to
M
RISK reduce risk to Low. Treatment options to reduce to Low risk should be
implemented as soon as practicable.
L LOW RISK Usually acceptable to regulators. Where treatment has been required to reduce
the risk to this level, ongoing maintenance required.
VERY LOW
VL Acceptable. Manage by normal slope maintenance procedures.
RISK
Note: (1) The implications for a particular situation are to be determined by all parties to the risk assessment and may
depend on the nature of the property at risk; these are only given as a general guide.
The risk assessment essentially involves combining the elements of ‘Likelihood’ and ‘Consequence’ for the
potential hazards identified across the proposed development area in a qualitative manner. Relative levels of
risk and their implications are given in Table 3.
It should be noted that the stability assessment above relates to the global stability of the areas surrounding
the proposed development (as shown in Figure 1). Our assessment does not include areas surrounding the
existing residence.
Table 2: Qualitative Risk Assessment for Property (Based on AGS 2007).
Assessed
Hazard Likelihood Consequence Comments
Risk
The likelihood of shallow failure is assessed as Unlikely
due to the absence of groundwater (during our
investigation), the nature of the soils found in our
Shallow failure investigation and site slopes directing water away from
of soils above the proposed development. The consequence is
Unlikely Minor Low
the footing considered Minor, if the structures are lightweight/flexible
zone and founded well into the very stiff to hard extremely
weathered material or mudstone underlying weathered at
depths below about 1.2 m BGL as recommended in this
report. The resultant risk is Low.
Deep-seated
failure through
very stiff to A likelihood of Rare is assessed for global instability due
hard residual to the competent nature of the residual soils, weathered
Rare Medium Low
soils; extremely materials; and mudstone. A consequence of Medium has
weathered been assigned, with a resultant risk of Low.
material or
weathered rock
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Based on our slope stability assessment, it is our opinion that there is a Low Risk for the proposed
development, provided that the recommendations in this report are implemented. This level of risk is
normally acceptable to regulators (i.e. Council).
The recommendations provided in this report are provided to enable an inferred factor of safety against
landslide of over 1.5. The above recommendations must be reviewed when earthworks and building designs
are finalised, to confirm an acceptable factor of safety is achieved.
7.0 DEVELOPMENT IMPACTS & MITIGATION MEASURES
It is our opinion that this site is suitable for the proposed development, from a geotechnical viewpoint, subject
to implementation of the recommendations provided in this report. The potential impacts on slope stability of
the proposed development have been considered, and the measures recommended below have been
designed to mitigate those impacts. Building development should follow normal slope maintenance
procedures and the document ‘General Guidelines for Hillside Construction’, which is attached in Appendix
D.
7.1 Earthworks
Earthworks should be carried out in accordance with Australian Standard AS 3798-2007 ‘Guidelines on
Earthworks for Commercial and Residential Developments’. Filling should not exceed 1 m in depth.
7.1.1 Site Preparation & Trafficability
Site preparation in building and pavement areas should include the following:
Strip the surface of vegetation, organic matter, organic rich soils (topsoils) and severely root affected
soils.
‘Proof roll’ the stripped surface by several passes of a minimum 10 tonne roller to identify loose or
soft areas.
An experienced geotechnical engineer from Core should carry out an inspection of the subgrade 'proof roll'.
Loose/soft areas identified by proof rolling and/or inspection will require treatment by either of the following
methods:
Over-excavation and replacement with suitable fill compacted in layers (refer Section 7.1.4); or
Re-compaction of the loose or soft material provided that it does not contain substantial organic
matter or deleterious substances.
At the time of the investigation the site was trafficable with a tracked excavator with caution. Following
stripping of topsoil materials, trafficability issues should be anticipated following rainfall. Due to the potential
for poor trafficability across the site, it would be prudent to allow for the placement of a compacted granular
fill layer particularly in access road and laydown areas. A geotextile separation layer between the natural
ground and granular fill may also be required.
7.1.2 Excavations
Excavations into the residual soil, and extremely weathered materials/rock should be achievable using
conventional small to large earthmoving equipment (i.e. 6 to 20 tonne excavators).
Bands of higher strength mudstone may be encountered requiring ripper tyne excavation (e.g. as found in
test pit TP1).
7.1.3 Batter Slopes
For short-term construction periods, excavated un-surcharged faces could be battered at 1V:1H in the
residual stiff to hard clayey soils, and weathered material and underlying mudstone. Shoring will be required
to enable personnel entry into near vertical sided trenches deeper than 1 m.
Flatter batters may be required if significant groundwater seepage is encountered or if exposed faces are not
protected from erosion by rainfall.
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Permanent batters should not be steeper than 1V:2H in the natural stiff (or stiffer) clays. Batters in extremely
weathered mudstone may be constructed at 1V:1H (subject to inspection by Core).
Further positive support by engineer-designed retaining structures may also be required where space
restrictions prevent trimming of batters to safe slopes and where slopes are surcharged or near movement
sensitive structures (ref Section 7.2).
Permanent batters that are not retained should be protected from erosion (e.g. revegetation or stone
pitching).
7.1.4 Erosion Protection
Any excavations or disturbance of materials should be carefully monitored and managed during the
construction phase to minimise potential for scour/erosion and sediment run off.
Exposed soil (i.e. on batters or drains) should be protected from erosion by appropriate measures such as
re-vegetation and hydro-seeding, protective matting, geotextiles or hard facings. Temporary sediment control
should be adopted during construction where surface water will flow offsite. Concentrating surface runoff
should be avoided unless adequate erosion protection and flow dissipation is constructed.
7.2 Retaining Structures
Design for retaining structures could be carried out using a triangular pressure distribution applicable to the
wall type and based on the parameters listed in Table 4. The values in Table 4 assume that the walls are
fully drained and no allowance is included below for construction loading, up-slope footing loadings, and
backfill compaction stresses. Retaining walls should be founded as described in Section 7.3.
Positive permanent drainage (surface and subsoil) must be installed behind retaining walls to prevent the
development of hydrostatic pressures. Drainage outlets must extend beyond the ends of the walls.
Retaining wall backfill should be a loose, free draining granular material and should only be lightly
compacted as heavy compaction may raise the earth pressure to above the ‘at rest’ earth pressure.
Table 3: Retaining structure design parameters.
Lateral earth pressure coefficient
Unit Friction Non-
Cohesion, Yielding
Retained material weight angle yielding
cu (kPa)
(t/m3) (degrees)
Ka
Kp Ko
(cantilever)
Stiff clay - Residual Soil 1.8 25 50-100 0.41 2.5 0.58
Very Stiff to Hard Clay - Residual
1.9 30 100-200 0.33 3.00 0.50
Soil
Extremely Weathered
1.9 34 >1000 0.38 3.54 0.44
Material/Mudstone
Notes:
Ka - active; Ko - at rest; Kp - passive
For yielding walls active state develops when: Deflection > 0.001H to 0.004H (granular soil),
or deflection > 0.01H to 0.04H (cohesive soil)
7.3 Footings
The proposed structures could be supported on a combination of high-level strip/pad and/or piered footings
founded at least 300 mm into stiff (or stiffer) residual soils or extremely weathered material/mudstone below
depths of 1.2 m BGL. Design bearing pressures are provided in Section 7.3.2.
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7.3.1 Site Classification
The site classification was derived in accordance with Australian Standard AS 2870 Residential slabs and
footings which provides an indication of the likely magnitude of reactive (shrink and swell) movements
associated with normal seasonal soil moisture variations.
The subsurface profile encountered in the test pits at the proposed cabin locations comprises primarily stiff
(or stiffer) silty clay (residual soil) of low to medium plasticity and overlying weathered material and/or
mudstone.
A preliminary site classification of “Class H1” (in accordance with AS2870-2011) is recommended for such
site conditions. Laboratory testing will be required to confirm the site classification. If cut to fill works are
proposed this may alter the site classification and Core should be consulted.
It should be noted that the estimated order of movement is based on the existing soil profile and the
proposed founding conditions, including moisture content changes within soils due to normal seasonal
moisture variations only.
As the site soils are anticipated to be ‘reactive’, it will be necessary to ensure that ‘usual good practice’ is
adopted for design and detailing if control of reactive ground movement is desired. Such practices should
include the following:
Trees and shrubs should not be planted or be allowed to remain closer than their mature height to
movement sensitive features.
Soil moisture should not be allowed to change during or following construction.
Site grades should be designed to readily shed water and prevent ponding around footings and other
movement sensitive areas.
The proposed buildings should be made as “flexible” as possible to cope with reactive soil movements.
Services beneath the buildings should be kept to a minimum and should be designed to be flexible
(especially at building walls), and to prevent any leakage.
7.3.2 High Level Footings and Piers
Building loads could be supported by strip or pad footings taken into stiff (or stiffer residual clays or deeper
into extremely weathered material or mudstone (depths expected to be about 1 m to 1.5 m bgl).
The following allowable bearing pressures may be adopted in natural materials for design purposes:
- Shallow footings on Stiff (or Stiffer) Clays 100 kPa
- Shallow footings on Very Stiff/Hard Clays 200 kPa
Extremely Weathered Material
- Bored piers are founded in Extremely Weathered Material/ 500 kPa
Weathered Mudstone
To achieve the recommended allowable bearing pressures, founding materials must be dry and cleaned of
any loose, disturbed or saturated materials prior to pouring concrete. Footing excavations must be inspected
by an engineer from Core to confirm the foundation material meets the design pressure requirements.
If any soil conditions encountered during the footing excavations are found to differ from those noted in the
geotechnical investigation, Core should be notified immediately, and an inspection of the footing excavations
should be carried out to assess if changes to footing design are required.
All proposed footings should found such that they are not adversely affected by any adjacent excavations,
batter slopes, trenches, or retaining walls that are not designed to support building or fill loads.
To minimise the potential for any adverse interaction effects, footings should found at least below a plane
extending 1 m horizontally from the base of trenches/batter slopes/excavations/ retaining walls, then rising
up at 1V:1H. This requirement is illustrated in the following diagram.
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7.4 Drainage
Site drainage should be designed to readily remove surface water, minimise water infiltration into the slope,
and to prevent ponding of water on subgrade areas during construction and also adjacent to foundations,
and driveways once construction is completed.
Roof water, including overflow from rainwater tanks, and water collected from hard surfaces (e.g. driveways)
must be directed by pipes or lined channels to a legal point of discharge.
Shallow subsurface cut-off drains should be installed upslope of building areas in order to intercept and
divert potential subsurface seepage. Diversion drains should be constructed above the crest of any cut or fill
embankments.
7.5 General Foundation Maintenance
The CSIRO document Foundation maintenance and footing performance: A Homeowner’s Guide (2003) is
attached in Appendix E for your information. This advice should be considered in the construction and
maintenance of the proposed development.
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8.0 WASTEWATER TREATMENT AND DISPOSAL
An assessment of the type and configuration of wastewater systems that may be suitable for a proposed
development requires the following:
Assumptions to be made regarding the development configuration and probable wastewater flow; and
Evaluation of the terrain-soil combinations to identify distinct units.
8.1 Wastewater Flow Design Allowance
For the proposed development, comprising two single bedroom, single level eco-cabins we understand that
the maximum occupancy will be 4 Equivalent Persons (EP) total. For each EP, a typical wastewater flow
allowance has been taken from Table H4 of Australian Standard AS1547:2012 On-site domestic wastewater
management (Table H4 refers to New Zealand conditions, and AS1547 allows for a reduction of about 30%
of wastewater to allow for differences between Australian and NZ climatic conditions), as follows:
• Guests of cabins (4 EP) 150 L/person/day (roof water supply)
We therefore estimate a typical total wastewater flow rate of 600 L/day during the maximum occupancy of
the cabins.
Wastewater flow rates may be reduced by the adoption of water reduction fixtures. Conversely, the use of
extra wastewater producing fixtures (e.g. spa baths) and/or additional cabins etc. with more people has the
potential to increase the wastewater flow rate.
It should be noted that sewage treatment works discharged through an irrigation scheme with a total daily
peak design capacity of 21 to 100 EP are deemed to be an environmental relevant activity and must comply
with the obligations of the Environmental Protection Act 1994, and the regulations made under that Act. The
proposed development does not meet this threshold of assessment; however, the addition of more cabins
could result in exceeding the threshold and require further assessment.
8.2 Terrain-Soil Assessment
The terrain-soil combination(s) at a site are assessed so that an expected available area can be delineated
for suitable methods of wastewater treatment and land application.
The terrain across the site has been categorised in accordance with the slope configurations described in
Figure C2 of AS1547:2012, which also describes the relationship between the shape of the slope and
surface drainage. The topography across the site varies but could generally be described as Linear Planar
to Linear Divergent in the area where effluent disposal is proposed (Ref. Figure No. 1).
At the location of the potential effluent disposal area(s) (ref. Figure 1), subsurface conditions comprised silty
clay of low to medium plasticity, broadly corresponding to Soil Category 5 (Light Clay; Strongly Structured)
which has an indicative permeability of 0.12 m/day to 0.5 m/day (Table 5.1 of AS 1547:2012) and could be
described as “poorly to moderately drained”.
Results of insitu permeability testing, indicated permeability values in the range 0.6 m/day adjacent toTP4 (in
clay soils).
A second test was performed at TP5 due to that area possessing a flatter gradient and potentially being an
effluent disposal site. The test indicated a permeability of about 1.2 m/d in sandy soil. However, it was
reassessed that location is potentially a catchment of surface runoff and, actually possessed standing water
(in parts), and as such that area was not further considered.
8.3 Recommendations
Having consideration for the terrain-soil assessment and environmental constraints of the site, it is
recommended that treated wastewater be directed to a surface or shallow subsurface drip irrigation system.
The wastewater treatment system(s) must be licensed to produce minimum Secondary standard effluent in
accordance with the Queensland Plumbing and Wastewater Code (QPW Code). Treated greywater may be
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used as irrigation provided it is disposed of in a manner appropriate for its end use as indicated in the QPW
Code.
Land application of secondary treated wastewater using surface irrigation (spray or drip) is limited to ground
slopes less than 10% (about 6°). Subsurface irrigation may be adopted for ground slopes up to 30% (about
17°).
Based on Table 5.2 and Table M1 of AS1547 and adjusted for slope angle in accordance with Table M2, a
Design Irrigation Rate (DIR) of 1.5 mm/day is considered appropriate for the proposed facility. This allows for
a sloping site of up to 30%, whereby the DIR of 3 mm/day for a Category 5 soil is reduced by 50%.
For Category 5 soils, Table M1 of AS 1547 recommends that a drip irrigation system have a depth of
150 mm to 250 mm in good quality topsoil.
Therefore, about 400 m² of irrigation area would be required for an assumed total wastewater flow rate of
600 L/day. Indicative irrigation areas are shown on Figure 1. The disposal field may be split into two or more
areas but must total at least 400 m2.
Positioning (‘setbacks’) of the land application systems should be in accordance with the horizontal
separation distances recommended in the QPW Code as outlined in Table 4.
Table 4: Horizontal separation distances for irrigation areas
Description Secondary Effluent Advanced Secondary Effluent
To permanent/intermittent
watercourse, dam, drainage 30 m 10 m
channel
To bore or well used for domestic
30 m 10 m
water supply
Property boundaries, paths,
walkways, recreation areas,
4m/2m 4m/2m
footings of buildings, retaining
walls
In ground potable water tank 6m 6m
Dwelling, recreation area
10 m 10 m
(surface irrigation only)
Water edge of swimming pool,
6m 6m
cutting in soil
An unsaturated soil depth of 0.6 m (i.e. depth to rock or wet soil) is recommended in the QPW Code for
Secondary effluent. Test pits in the vicinity of the proposed irrigation area indicate sufficient available soil
depths and absence of groundwater to at least 0.6 m depth.
The system may be required to be positioned upslope or at a reduced level similar to proposed buildings
whilst adhering to the separation distances recommended in the QPW Code (Table 7) and will require a
suitable pump system.
8.3.1 System Construction
Construction of the wastewater land application area should be carried out in accordance with Section 6 of
AS 1547 and Sunshine Coast Council requirements. In order to minimise potential deleterious
environmental impacts associated with wastewater application at the site, the following practices should be
employed:
The subsurface irrigation field(s) is to be located on land sloping at less than 17° (indicative suitable
areas are shown on Figure 1). Alternatively, a disposal field could be created on steeper land using
cut/fill earthworks supported by a retaining wall. It is anticipated that for such a field, the wall would be
generally less than 1 m high. If cut is undertaken, it must be limited to ensure at least 600 mm of soil
overlies rock. Fill must be limited to no more than 1 m high.
J002915-001-R-Rev0 13
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 17
Wingara Hills Pty Ltd
Topsoil material won from any stripping works associated with construction could be used to
supplement the soil within the disposal field.
To evenly distribute wastewater throughout the irrigation area, a pressure equalisation system should
be installed.
Irrigation laterals should be constructed parallel to the natural ground surface contours.
A cut off berm or diversion drain must be constructed upslope to divert surface water away from the
irrigated area.
Signage should be erected at the boundaries of the area in at least two places in accordance with
Council requirements to warn people regarding the presence of wastewater pipes (e.g. “Sewage
Effluent Pipework Installed Below – DO NOT DIG” or “Recycled Water – Avoid Contact - DO NOT
DRINK”).
Detailed design of the effluent disposal system must be carried out by a Registered Evaluator once the
facility design is finalised.
9.0 SUMMARY AND CONCLUSIONS
From a geotechnical viewpoint, the site is suitable for the proposed development. This recommendation is
subject to the implementation of the measures specified in this report.
It is also our opinion that the site is suitable for on-site disposal of effluent. Our assessment indicates that a
minimum Secondary HSTP with 280 m2 irrigation area is required for the proposed facility.
10.0 LIMITATIONS
Your attention is drawn to the document, Limitations which is attached in Appendix F.
J002915-001-R-Rev0 14
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 18
Core Consultants Pty Ltd
Yours sincerely,
Tom Sutton Darryn Quinn
BEng (Hons) (Geotechnical and Civil) MIEAust BE(Geological) MIEAust RPEQ 7602
Geotechnical Engineer Principal Geotechnical Engineer
TS/DQ/ts
A.B.N. 75 603 384 050
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 19
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© CORE CONSULTANTS PTY. LTD. INFORMATION CONTAINED ON THIS DRAWING IS THE COPYRIGHT OF CORE CONSULTANTS PTY. LTD. UNAUTHORISED USE OR REPRODUCTION OF THIS PLAN EITHER WHOLLY OR IN PART WITHOUT WRITTEN PERMISSION INFRINGES COPYRIGHT.
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Esri Community Maps Contributors, Department of Resources, DESI, © OpenStreetMap, Microsoft, Esri, TomTom, Garmin, METI/NASA, USGS, Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community 1:1250
487800 487850 487900 487950 488000 488050 488100 488150 488200
EASTING (m)
LEGEND
CLIENT PROJECT
{
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v
x APPROXIMATE TEST PIT LOCATION URBN TOWN PLANNING PROPOSED CABINS - 224 MORAN GROUP RD, KIN Section 20
KIN
DRAWN BY DATE DRAWING TITLE
APPROXIMATE 1M CONTOURS
TS 30/07/2025
EXAMPLE EFFLUENT DISPOSAL AREA CHECKED BY DATE
SITE PLAN
DQ 31/07/2025
SCALE SHEET SIZE PROJECT No DOC No DOC TYPE FIGURE No REVISION
www.coreconsultants.com.au 1:1250 A3 J002915 001 R F001 0 SHEET 1 OF 1
Plot Date: 31 July 2025 Time: 3:17 PM By: tsutton Path: C:\Users\tsutton\OneDrive - Core Consultants\Documents\ArcGIS\J002915-GIS\J002915.aprx
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 21
Appendix A
Reports of Test Pits and Explanatory Notes
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 22
REPORT OF TESTPIT: TP1
East : 488,010.00 Sheet : 1 OF 1
Client : UBRN Town Planning North : 7,100,923.00 56J Logged : TS
Project : Proposed Cabins Contractor : Cooper Civil Logged Date 29/07/2025
Location : 224 Moran Group Rd, Kin Kin QLD 4571, Australia Excavator : Kubota KX040-4 Checked : DQ
Job No : J002915 Inclination : -90 deg Checked Date : 01/08/2025
GROUP SYMBOL
DEPTH (meters)
CONSISTENCY
PENETRATION
GRAPHIC LOG
DESCRIPTION
RESISTANCE
MOISTURE
DEPTH RL
METHOD
DENSITY
WATER
SAMPLE OR DCP TEST (Blows per 100m)
SOIL/ROCK MATERIAL DESCRIPTION
FIELD TEST
0 5 10 15 20
CLAY (TOPSOIL): medium plasticity, dark brown , trace fine grained
CI sand, with rootlets. w ≈ PL F- St
0.2
Silty CLAY (RESIDUAL SOIL): medium plasticity, brown, trace rootlets.
DS 0.2- 0.6m CI St
L
0.6
Silty CLAY (RESIDUAL SOIL): low to medium plasticity, brown, orange,
pale grey and white.
w<
DS 0.6- 1.1m CL- CI PL- w
≈ PL
1 77.0
1.1
Silty CLAY (EXTREMELY WEATHERED MUDSTONE): medium
plasticity, pale grey to grey mottled orange- red- brown, with fine to
CI coarse grained gravel, with cobbles. VSt
Groundwater not encountered
1.4
M becoming hard.
EX
CI H
1.8
MUDSTONE: fine grained, grey stained brown- orange- white, lamination
fabric, very low to low strength, highly weathered.
2 76.0
VLS-
DS 1.8- 2.6m MUD M
LS
M-
H
2.6
Silty CLAY (EXTREMELY WEATHERED MUDSTONE): medium
plasticity, pale grey to grey mottled orange- red- brown, with fine to
coarse grained gravel, with cobbles. w<
DS 2.6- 3.0m CI PL- w H
≈ PL
75.0
TP1 Terminated at 3 m
This report must be read in conjunction with accompanying notes and abbreviations. It has been prepared for geotechnical
purposes only, without attempt to assess possible contamination. Any references to potential contamination are for information
only and do not necessarily indicate the presence or absence of soil or groundwater contamination.
Page 1 of 1
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 23
REPORT OF TESTPIT: TP2
East : 487,994.00 Sheet : 1 OF 1
Client : UBRN Town Planning North : 7,100,938.00 56J Logged : TS
Project : Proposed Cabins Contractor : Cooper Civil Logged Date 29/07/2025
Location : 224 Moran Group Rd, Kin Kin QLD 4571, Australia Excavator : Kubota KX040-4 Checked : DQ
Job No : J002915 Inclination : -90 deg Checked Date : 01/08/2025
GROUP SYMBOL
DEPTH (meters)
CONSISTENCY
PENETRATION
GRAPHIC LOG
DESCRIPTION
RESISTANCE
MOISTURE
DEPTH RL
METHOD
DENSITY
WATER
SAMPLE OR
SOIL/ROCK MATERIAL DESCRIPTION DCP TEST (Blows per 100m)
FIELD TEST
0 5 10 15 20
CLAY (TOPSOIL): medium plasticity, dark brown, trace fine grained
CI sand, with rootlets. w ≈ PL St
0.2
Silty CLAY (RESIDUAL SOIL): medium plasticity, brown, trace rootlets.
w<
CI PL- w
DS 0.2-1.0m becoming very stiff. ≈ PL
VSt
1
1 78
Silty CLAY (EXTREMELY WEATHERED MUDSTONE): medium
plasticity, pale grey to grey mottled brown- orange, with fine to coarse
grained gravel, with cobbles.
L
Groundwater not encountered
becoming hard.
EX
DS 1.5- 2.0m CI w < PL H
2 77
2.5
MUDSTONE: fine grained, pael grey to grey stained brown- orange,
lamination fabric, very low strength, highly weathered, frequent lenses of
extremely weathered material.
M DS 2.5- 3m MUD M VLS
76
TP2 Terminated at 3 m
This report must be read in conjunction with accompanying notes and abbreviations. It has been prepared for geotechnical
purposes only, without attempt to assess possible contamination. Any references to potential contamination are for information
only and do not necessarily indicate the presence or absence of soil or groundwater contamination.
Page 1 of 1
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 24
REPORT OF TESTPIT: TP3
East : 488,034.00 Sheet : 1 OF 1
Client : UBRN Town Planning North : 7,100,946.00 56J Logged : TS
Project : Proposed Cabins Contractor : Cooper Civil Logged Date 29/07/2025
Location : 224 Moran Group Rd, Kin Kin QLD 4571, Australia Excavator : Kubota KX040-4 Checked : DQ
Job No : J002915 Inclination : -90 deg Checked Date : 01/08/2025
GROUP SYMBOL
DEPTH (meters)
CONSISTENCY
PENETRATION
GRAPHIC LOG
DESCRIPTION
RESISTANCE
MOISTURE
DEPTH RL
METHOD
DENSITY
WATER
SAMPLE OR DCP TEST (Blows per 100m)
SOIL/ROCK MATERIAL DESCRIPTION
FIELD TEST
0 5 10 15 20
CLAY (TOPSOIL): medium plasticity, dark brown, trace fine grained
sand, with rootlets.
CI w ≈ PL F
0.3
Silty CLAY (RESIDUAL SOIL): medium plasticity, brown, trace rootlets.
CI St
L
0.8
Silty CLAY (RESIDUAL SOIL): medium plasticity, pale grey, brown and w<
CI red, trace rootlets. PL- w F- St
≈ PL
1
1 77
becoming very stiff.
CI VSt
1.2
Silty CLAY (EXTREMELY WEATHERED MUDSTONE): medium
Groundwater not encountered
CI plasticity, pale grey to white mottled brown- red- orange , with fine to
coarse grained gravel, with cobbles.
1.4
becoming hard.
EX
DS 1.8- 2.0m
M
2 76
CI H
2.7
MUDSTONE: fine grained, pale grey to white stained brown- orange-
red, lamination fabric, very low to low strength, highly weathered,
M- frequent lenses of extremely weathered material. VLS-
MUD M
H LS
75
TP3 Terminated at 3 m
This report must be read in conjunction with accompanying notes and abbreviations. It has been prepared for geotechnical
purposes only, without attempt to assess possible contamination. Any references to potential contamination are for information
only and do not necessarily indicate the presence or absence of soil or groundwater contamination.
Page 1 of 1
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 25
REPORT OF TESTPIT: TP4
East : 488,087.00 Sheet : 1 OF 1
Client : UBRN Town Planning North : 7,100,948.00 56J Logged : TS
Project : Proposed Cabins Contractor : Cooper Civil Logged Date 29/07/2025
Location : 224 Moran Group Rd, Kin Kin QLD 4571, Australia Excavator : Kubota KX040-4 Checked : DQ
Job No : J002915 Inclination : -90 deg Checked Date : 01/08/2025
GROUP SYMBOL
DEPTH (meters)
CONSISTENCY
PENETRATION
GRAPHIC LOG
DESCRIPTION
RESISTANCE
MOISTURE
DEPTH RL
METHOD
DENSITY
WATER
SAMPLE OR
SOIL/ROCK MATERIAL DESCRIPTION DCP TEST (Blows per 100m)
FIELD TEST
0 5 10 15 20
Sandy CLAY (TOPSOIL): low to medium plasticity, dark brown, fine to
medium grained sand, with rootlets.
CL- CI w ≈ PL F- St
0.3
Clayey SAND (RESIDUAL SOIL): fine to medium grained, brown,
SP- medium plasticity clay. M L- MD
SC
0.5
becoming dense.
DS 0.3- 0.9m
SP-
D
SC
0.9
Sandy CLAY (RESIDUAL SOIL): low to medium plasticity, dark brown,
1 70 fine to medium grained sand.
CL- CI w ≈ PL St
Groundwater not encountered
1.2
Silty CLAY (RESIDUAL SOIL): high to medium plasticity, pale grey
mottled re- brown- orange , with fine to medium grained sand.
EX
L
CI- CH
1.7
DS 1.5- 2.0m becoming stiff.
CI- CH VSt
2
2 69
Silty CLAY (RESIDUAL SOIL): high to medium plasticity, pale grey
mottled re- brown- orange , with fine to medium grained sand.
CI- CH
TP4 Terminated at 2.8 m
This report must be read in conjunction with accompanying notes and abbreviations. It has been prepared for geotechnical
purposes only, without attempt to assess possible contamination. Any references to potential contamination are for information
only and do not necessarily indicate the presence or absence of soil or groundwater contamination.
Page 1 of 1
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 26
REPORT OF TESTPIT: TP5
East : 488,024.00 Sheet : 1 OF 1
Client : UBRN Town Planning North : 7,100,831.00 56J Logged : TS
Project : Proposed Cabins Contractor : Cooper Civil Logged Date 29/07/2025
Location : 224 Moran Group Rd, Kin Kin QLD 4571, Australia Excavator : Kubota KX040-4 Checked : DQ
Job No : J002915 Inclination : -90 deg Checked Date : 01/08/2025
GROUP SYMBOL
DEPTH (meters)
CONSISTENCY
PENETRATION
GRAPHIC LOG
DESCRIPTION
RESISTANCE
MOISTURE
DEPTH RL
METHOD
DENSITY
WATER
SAMPLE OR
SOIL/ROCK MATERIAL DESCRIPTION DCP TEST (Blows per 100m)
FIELD TEST
0 5 10 15 20
CLAY (TOPSOIL): medium plasticity, dark brown, with fine to medium
grained sand, trace fine to medium grained gravel, with rootlets.
CI w ≈ PL F
0.3
Sandy CLAY (RESIDUAL SOIL): low to medium plasticity, brown
and grey, fine to coarse grained sand, trace fine grained gravel.
Groundwater not encountered
CL- CI F- St
EX
L
1 48
1.1
CLAY (RESIDUAL SOIL): medium plasticity, brown and orange, with
fine to coarse grained sand, trace fine to medium grained gravel, trace
cobbles.
CI St
TP5 Terminated at 1.5 m
This report must be read in conjunction with accompanying notes and abbreviations. It has been prepared for geotechnical
purposes only, without attempt to assess possible contamination. Any references to potential contamination are for information
only and do not necessarily indicate the presence or absence of soil or groundwater contamination.
Page 1 of 1
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 27
EXPLANATION OF NOTES, ABBREVIATIONS & TERMS
USED ON BOREHOLE AND TEST PIT REPORTS
DRILLING/EXCAVATION METHOD
AS Auger Screwing RD Rotary blade or drag bit NQ Diamond Core - 47 mm
AD Auger Drilling RT Rotary Tricone bit NMLC Diamond Core - 52 mm
*V V - Bit RAB Rotary Air Blast HQ Diamond Core - 63 mm
T TC - Bit, e.g. ADT RC Reverse Circulation HMLC Diamond Core – 63mm
HA Hand Auger PT Push Tube BH Tractor Mounted Backhoe
ADH Hollow Auger CT Cable Tool Rig EX Tracked Hydraulic Excavator
DTC Diatubre Coring JET Jetting EE Existing Excavation
WB Washbore or Bailer NDD Non-destructive digging HAND Excavated by Hand Methods
PENETRATION/EXCAVATION RESISTANCE
L Low resistance . Rapid penetration possible with little effort from the equipment used
M Medium resistance. Excavation possible at an acceptable rate with moderate effort from equipment used
H High resistance to penetration/excavation. Further penetration is possible at a slow rate
R Refusal or Practical Refusal. No further progress possible without the risk of damage or unacceptable wear to the digging implement
or machine.
These assessments are subjective and are dependent on many factors including the equipment power, weight, condition of excavation or drilling tools,
and the experience of the operator.
WATER
Water level shown at date Partial water loss
Water inflow Complete water loss
GROUNDWATER NOT The observation of groundwater whether present or not, was not possible due to drilling water, surface seepage or cave in
OBSERVED of the borehole/test pit.
GROUND WATER NOT The borehole/test pit was dry soon after excavation. However, groundwater could be present in less permeable strata.
ENCOUNTERED Inflow may have been observed had the borehole/test pit been left open for a longer period.
SAMPLING AND TESTING
SPT Standard Penetration Test to AS1289.6.3.1-2004
4,7,11 N=18 4,7,11 = Blows per 150mm N = Blows per 300mm penetration following 150mm seating
30/80mm Where practical refusal occurs, the blows and penetration for that interval are reported
RW Penetration occurred under the rod weight only
HW Penetration occurred under the hammer and rod weight only
HB Hammer double bouncing on anvil
DS Disturbed Sample
BDS Bulk disturbed sample
G Gas Sample
W Water sample
FP Field permeability test over section noted
FV Field vane shear test expressed as uncorrected shear strength (sv = peak value)
PID Photoionisation Detector reading in ppm
PM Pressuremeter test over section noted
PP Pocket penetrometer test expressed as instrument reading in kPa
U63 Thin walled tube sample - number indicates nominal sample diameter in millimetres
WPT Water pressure tests
DCP Dynamic cone penetration test
CPT Dynamic cone penetration test
CPTu Static cone penetration test with pore pressure (u) measurement
ROCK CORE RECOVERY
TCR = Total Core Recovery (%) SCR = Solid Core Recovery (%) RQD = Rock Quantity Designation (%)
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 28
METHOD OF SOIL DESCRIPTION USED ON BOREHOLE AND TEST PIT
REPORTS
FILL CLAY (CL,CI, or CH)
GRAVEL (GP or SW) ORGANIC SOILS (OL or OH or Pt)
SAND (SP or SW) COBBLES or BOULDERS
SILT (ML or MH)
Combinations of these basic symbols may be used to indicate mixed materials such as sandy clay.
CLASSIFICATION AND INFERRED STRATIGRAPHY
Soil and Rock is classified and described in Reports of Boreholes and Test Pits using the preferred method given in AS 1726 - 2017. The material proper-
ties are assessed in the field by visual/tactile methods.
PARTICLE SIZE PLASTIC PROPERTIES
Major
Sub Division Particle Size
Division
Boulders >200 mm
Cobbles 63 - 200 mm
Gravel Coarse 20 - 63 mm
Gravel Medium 6.7 - 20 mm
Gravel Fine 2.36 - 6.7 mm
Sand Coarse 0.6 - 2.36 mm
Sand Medium 0.21 - 0.6 mm
Sand Fine 0.075 - 0.21 mm
Silt 0.002 - 0.075 mm
Clay <0.002 mm
MOISTURE CONDITION FOR COARSE GRAINED SOIL AS 1726 - 2017
Symbol Term Description
D Dry Non-cohesive and free running
M Moist Soil feels cool, darkened in colour, tends to stick together
W Wet Soil feels cool, darkened in colour, soil sticks together, free water forms when handling
MOISTURE CONDITION FOR FINE GRAINED SOIL AS1726 - 2017
Symbol Term Description
W<PL Moist dry of liquid limit Hard and friable or powdery
W = PL Moist near plastic limit Soils can be molded at a moisture condition approximately equal to the plastic limit
W >PL Moist, wet of plastic limit Soils usually weakened and free water forms on hands when handling
W = LL Wet near plastic limit
W > LL Wet, wet of liquid limit
CONSISTENCY TERMS FOR AS1726—2017 RELATIVE DENSITY OF COARSE GRAINED SOILS AS1726—2017
COHESIVE SOILS
Symbol Term Density Index % SPT ‘N’ #
Symbol Term Undrained Shear
VL Very Loose Less than 15 0 to 4
Strength
L Loose 15 to 35 4 to 10
VS Very Soft 0 to 12 kPa
S Soft 12 to 25 kPa MD Medium Dense 35 to 65 10 to 30
F Firm 25 to 50 kPa D Dense 65 to 85 30 to 50
St Stiff 50 to 100 kPa VD Very Dense Above 85 Above 50
VSt Very Stiff 100 to 200 kPa In the absence of test results, consistency and density may be assessed from correlations with
the observed behaviour of the material.
H Hard Above 200 kPa
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 29
TERMS FOR ROCK MATERIAL STRENGTH & WEATHERING AND
ABBREVIATIONS FOR DEFECT DESCRIPTIONS
ROCK MATERIAL STRENGTH CLASSIFICATION AS1726—2017
Symbol Term Uniaxial Point Load Field Guide
Strength Is (50)
Compressive
(MPa)
Strength (MPa)
VL Very Low 0.6 to 2 0.03 to 0.1 Material crumbles under firm blows with sharp end of pick. Pieces up to 30 mm thick can
Strength be broken with finger pressure.
L Low Strength 2 to 6 0.1 to 0.3 Easily scored with knife. Indentations 1 mm to 3 mm show in the specimen with firm
blows of the pick point. A piece of core 150 mm by 50 mm may be broken by hand. Sharp
edges of core are friable and break during handling.
M Medium 6 to 20 0.3 to 1 Readily scored with a knife. A piece of core 150 mm by 50 mm can be broken by hand
Strength with difficulty.
H High Strength 20 to 60 1 to 3 A piece of core 150 mm by 50 mm cannot be broken by hand but can be broken by a pick
with a single firm blow. Rock rings under hammer.
VH Very High 60 to 200 3 to 10 Hand specimen breaks with pick after more than one blow. Rock rings under hammer.
Strength
EH Extremely High Above 200 Above 10 Specimen requires many blows with geological pick to break through intact material. Rock
Strength rings under hammer.
= Diametral Point Load Test = Axial Point Load Test
CLASSIFICATION OF MATERIAL AS1726—2017
WEATHERING
Symbol Term Field Guide
RS Residual Soil (Note 1) Material is weathered to such an extent that it has soil properties. Mass structure and material texture and
fabric of original rock are no longer visible but the soil has not been significantly transported.
XW Extremely Weathered Material is weathered to such an extent that is has soil properties. Mass structure and material texture and
(Note 1) fabric of original rock are still visible.
HW Highly Weathered (Note 2) The whole rock mass is discoloured, usually by iron staining or beaching to the extent that the colour of the
original rock is not recognizable. Rock strength is significantly changed by weathering. Some primary miner-
als have weathered to clay minerals. Porosity may be increased by leaching, or may be decreased due to
deposition of weathering products in pores.
MH Moderately Weathered The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the
(Note 2) colour of the original rock is not recognizable, but shows little or no change in strength from fresh rock.
SW Slightly Weathered Pock is partially discoloured with staining or bleaching along joints but shows little or no change of strength
from fresh rock.
FR Fresh Rock shows no signs of decomposition of individual minerals or colour change.
Note 1 The term ‘Extremely Weathered rock’ is misleading as the material has soil properties. The word ‘rock’ should be replaced with the name
of the original rock of the word ‘material’, eg. Extremely Weathered granite or Extremely Weathered material.
Note 2 Where it is not possible to distinguish between ‘Highly Weathered’ and ‘Moderately Weathered’ rock the term ‘Distinctly Weathered’ may
be used.
DEFECT TYPE/DESCRIPTION DEFECT PROFILE DEFECT ROUGHNESS
Symbol Description DESCRIPTION
B Bedding Parting V Vein
PL Planar
Symbol Description
J Joint HB/DB Handling/Drilling St Stepped
Break Sl Slickenside
Un Undulating
EW Extremely Weathered C Contact Sm Smooth
DEFECT INFILL DESCRIPTION
Seam
Symbol Description Ro Rough
FZ Fracture Zone L Cleavage Vertical Boreholes - The dip
Cn Clean: No visible
coating (inclination from horizontal) for the
CZ/S Crushed Zone/Seam X Foliation defect is given.
Sn Stain: Coated 1 to
3 mm Inclined Boreholes - The inclination
IS Infilled Seam S Schistocity is measured as the acute angle to the
Vr Veneer: < 1 mm core axis.
SZ/S Sheared Zone/Seam Ct Coating: 1 to 3
mm
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 30
Appendix B
Insitu Permeability Test Results
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 31
CONSTANT HEAD TEST
Talsma Hallam Method AS/NZ 1547:2000 Appendix 4.1F
Client URBN Town Planning Hole No TP04
Project ECOCABINS Test Date 29/07/2025
Location 224 Moran Group Rd, Kin Kin Project No. J002915
dh
Tested by TS Checked
Co-ordinates 488087 / 7100948
Depth of Hole (Lh) 38.00 cm Vegetation
Tube below Surface (Lt) 15.00 cm Rootlets to 0.2m
Length to Air Inlet (Ls) 10.0 cm Mature trees adjacent ~6m
Test Section (H) 23 cm Soil moisture prior to test Lt
Diameter of test section (Dh) 6.00 cm W=PL / Moist Dt
Ls Lh
Diameter of tube (Dt) 4.330 cm
Static depth to gw (hs) 93.00 cm General comments (soil structure, H
Dh
Depth Impermeable Layer (S) 150.00 cm macro pores, water logging etc)
Radius of Tube (R) 2.17 cm Topsoil / Resdiual soil
Radius of Test Section (r) 3.00 cm S
Impermeable Layer
i = 1, 2, 3, ....n
120 Level in Difference
i Time Tube in level
t h dh K
100 (min) (cm) (cm) (m/s)
1 0.00 93.000 0.000 #DIV/0!
2 1.50 92.500 -0.500 #DIV/0!
80
3 2.50 92.000 -3.000 #DIV/0!
4 4.00 90.000 -4.000 #DIV/0!
60 h 5 4.33 89.000 -5.000 #DIV/0!
6 4.66 88.000 -6.000 #DIV/0!
7 5.0 87.0 -7.000 #DIV/0!
40 8 5.2 86.0 -8.000 #DIV/0!
9 5.5 85.0 -9.000 #DIV/0!
10 5.8 84.0 -10.000 #DIV/0!
20 11 6.0 83.0 -11.000 #DIV/0!
12 6.3 82.0 -12.000 #DIV/0!
0 13 6.6 81.0 -13.000 #DIV/0!
0.00 5.00 10.00 15.00 20.00 25.00 14 7.0 80.0 -18.000 #DIV/0!
15 8.3 75.0 -23.000 #DIV/0!
Time t (min) y = -3.2685x + 101.49
16 9.8 70.0 -28.000 #DIV/0!
R² = 0.9914
17 11.3 65.0 -33.000 #DIV/0!
18 12.8 60.0 -34.000 #DIV/0!
19 13.2 59.0 -35.000 #DIV/0!
Calculation of Hydraulic Conductivity, K : 20 13.5 58.0 -36.000 #DIV/0!
21 13.8 57.0 -37.000 #DIV/0!
π R 2 ∆h 22 14.0 56.0 -38.000 #DIV/0!
0.5sinh-1 H − r r
4.4 2 + 0.25 + 23 14.3 55.0 -39.000 #DIV/0!
∆t 2r H H
24 14.5 54.0 -40.000 #DIV/0!
K =
2πH 2 25 14.8 53.0 -41.000 #DIV/0!
26 15.0 52.0 -42.000 #DIV/0!
27 15.5 51.0 -43.000 #DIV/0!
28 15.8 50.0 -48.000 #DIV/0!
29 17.3 45.0 -53.000 #DIV/0!
30 18.7 40.0 -58.000 #DIV/0!
Equilibrium Hydraulic Conductivity : 31 20.2 35.0 -63.000 #DIV/0!
32 21.5 30.0 -65.000 #DIV/0!
Time Height 33 22.2 28.0 -68.000 #DIV/0!
Start from 4 4.0 90.0 34 22.8 25.0 -93.000 #DIV/0!
End at 34 22.8 25.0 35
K = -7.3E-06 m/sec 36
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Section 32
CONSTANT HEAD TEST
Talsma Hallam Method AS/NZ 1547:2000 Appendix 4.1F
Client URBN Town Planning Hole No TP5
Project ECOCABINS Test Date 29/07/2025
Location 224 Moran Group Rd, Kin Kin Project No. J002915
dh
Tested by TS Checked
Co-ordinates 488024 / 7100831
Depth of Hole (Lh) 33.00 cm Vegetation
Tube below Surface (Lt) 15.00 cm Rootlets to 0.2m
Length to Air Inlet (Ls) 10.0 cm Mature trees adjacent ~6m
Test Section (H) 18 cm Soil moisture prior to test Lt
Diameter of test section (Dh) 6.00 cm W=PL / Moist Dt
Ls Lh
Diameter of tube (Dt) 4.330 cm
Static depth to gw (hs) 1000.00 cm General comments (soil structure, H
Dh
Depth Impermeable Layer (S) 150.00 cm macro pores, water logging etc)
Radius of Tube (R) 2.17 cm Topsoil / Resdiual soil
Radius of Test Section (r) 3.00 cm S
Impermeable Layer
i = 1, 2, 3, ....n
100 Level in Difference
i Time Tube in level
90 t h dh K
(min) (cm) (cm) (m/s)
80
1 0.00 87.500 0.000 #DIV/0!
70 2 0.50 86.000 -1.500 #DIV/0!
3 0.80 85.000 -2.500 #DIV/0!
60
4 0.95 84.000 -3.500 #DIV/0!
50 h 5 1.10 83.000 -4.500 #DIV/0!
6 1.25 82.000 -5.500 #DIV/0!
40 7 1.4 81.0 -6.500 #DIV/0!
8 1.6 80.0 -7.500 #DIV/0!
30
9 1.8 79.0 -8.500 #DIV/0!
20 10 1.9 78.0 -9.500 #DIV/0!
11 2.0 77.0 -10.500 #DIV/0!
10 12 2.3 76.0 -11.500 #DIV/0!
0 13 2.5 75.0 -12.500 #DIV/0!
0.00 5.00 10.00 15.00 14 2.6 74.0 -13.500 #DIV/0!
15 2.8 73.0 -14.500 #DIV/0!
Time t (min) y = -4.4682x + 86.409
16 3.0 72.0 -15.500 #DIV/0!
R² = 0.9952
17 3.3 71.0 -16.500 #DIV/0!
18 3.5 70.0 -17.500 #DIV/0!
19 3.6 69.0 -18.500 #DIV/0!
Calculation of Hydraulic Conductivity, K : 20 3.8 68.0 -19.500 #DIV/0!
21 4.0 67.0 -20.500 #DIV/0!
π R 2 ∆h 22 4.3 66.0 -21.500 #DIV/0!
0.5sinh-1 H − r r
4.4 2 + 0.25 + 23 4.5 65.0 -22.500 #DIV/0!
∆t 2r H H
24 4.8 64.0 -23.500 #DIV/0!
K =
2πH 2 25 5.8 60.0 -27.500 #DIV/0!
26 7.0 54.0 -33.500 #DIV/0!
27 8.0 50.0 -37.500 #DIV/0!
28 9.3 45.0 -42.500 #DIV/0!
29 10.4 40.0 -47.500 #DIV/0!
30 11.7 35.0 -52.500 #DIV/0!
Equilibrium Hydraulic Conductivity : 31 13.0 30.0 -57.500 #DIV/0!
32 14.2 25.0 -62.500 #DIV/0!
Time Height 33
Start from 1 0.0 87.5 34
End at 32 14.2 25.0 35
K = -1.3E-05 m/sec 36
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Document Set ID: 24031832
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Section 33
Appendix C
Qualitative Risk Analysis Matrix (Australian Geomechanics
Vol 42 No 1 March 2007)
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 34
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX C: LANDSLIDE RISK ASSESSMENT
QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY
QUALITATIVE MEASURES OF LIKELIHOOD
Approximate Annual Probability
Implied Indicative Landslide
Description Descriptor Level
Indicative Notional Recurrence Interval
Value Boundary
10-1 5x10-2
10 years The event is expected to occur over the design life. ALMOST CERTAIN A
20 years The event will probably occur under adverse conditions over the
-2
10 100 years
design life.
LIKELY B
-3
-3 5x10 200 years
10 1000 years The event could occur under adverse conditions over the design life. POSSIBLE C
5x10-4 2000 years
The event might occur under very adverse circumstances over the
10-4 10,000 years
design life.
UNLIKELY D
-5 5x10-5 20,000 years
10 The event is conceivable but only under exceptional circumstances
100,000 years RARE E
over the design life.
-6 5x10-6 200,000 years
10 1,000,000 years The event is inconceivable or fanciful over the design life. BARELY CREDIBLE F
Note: (1) The table should be used from left to right; use Approximate Annual Probability or Description to assign Descriptor, not vice versa.
QUALITATIVE MEASURES OF CONSEQUENCES TO PROPERTY
Approximate Cost of Damage
Description Descriptor Level
Indicative Notional
Value Boundary
Structure(s) completely destroyed and/or large scale damage requiring major engineering works for
200% CATASTROPHIC 1
stabilisation. Could cause at least one adjacent property major consequence damage.
100%
Extensive damage to most of structure, and/or extending beyond site boundaries requiring significant
60% MAJOR 2
stabilisation works. Could cause at least one adjacent property medium consequence damage.
40%
Moderate damage to some of structure, and/or significant part of site requiring large stabilisation works.
20% MEDIUM 3
Could cause at least one adjacent property minor consequence damage.
10%
5% 1% Limited damage to part of structure, and/or part of site requiring some reinstatement stabilisation works. MINOR 4
Little damage. (Note for high probability event (Almost Certain), this category may be subdivided at a
0.5% INSIGNIFICANT 5
notional boundary of 0.1%. See Risk Matrix.)
Notes: (2) The Approximate Cost of Damage is expressed as a percentage of market value, being the cost of the improved value of the unaffected property which includes the land plus the
unaffected structures.
(3) The Approximate Cost is to be an estimate of the direct cost of the damage, such as the cost of reinstatement of the damaged portion of the property (land plus structures), stabilisation
works required to render the site to tolerable risk level for the landslide which has occurred and professional design fees, and consequential costs such as legal fees, temporary
accommodation. It does not include additional stabilisation works to address other landslides which may affect the property.
(4) The table should be used from left to right; use Approximate Cost of Damage or Description to assign Descriptor, not vice versa
91 Australian Geomechanics Vol 42 No 1 March 2007
Document Set ID: 24031832
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Section 35
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX C: – QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY (CONTINUED)
QUALITATIVE RISK ANALYSIS MATRIX – LEVEL OF RISK TO PROPERTY
LIKELIHOOD CONSEQUENCES TO PROPERTY (With Indicative Approximate Cost of Damage)
Indicative Value of 1: CATASTROPHIC 2: MAJOR 3: MEDIUM 4: MINOR 5:
Approximate Annual 200% 60% 20% 5% INSIGNIFICANT
Probability 0.5%
A – ALMOST CERTAIN 10-1 VH VH VH H M or L (5)
-2
B - LIKELY 10 VH VH H M L
C - POSSIBLE 10-3 VH H M M VL
D - UNLIKELY 10-4 H M L L VL
-5
E - RARE 10 M L L VL VL
-6
F - BARELY CREDIBLE 10 L VL VL VL VL
Notes: (5) For Cell A5, may be subdivided such that a consequence of less than 0.1% is Low Risk.
(6) When considering a risk assessment it must be clearly stated whether it is for existing conditions or with risk control measures which may not be implemented at the current
time.
RISK LEVEL IMPLICATIONS
Risk Level Example Implications (7)
Unacceptable without treatment. Extensive detailed investigation and research, planning and implementation of treatment
VH VERY HIGH RISK options essential to reduce risk to Low; may be too expensive and not practical. Work likely to cost more than value of the
property.
Unacceptable without treatment. Detailed investigation, planning and implementation of treatment options required to reduce
H HIGH RISK
risk to Low. Work would cost a substantial sum in relation to the value of the property.
May be tolerated in certain circumstances (subject to regulator’s approval) but requires investigation, planning and
M MODERATE RISK implementation of treatment options to reduce the risk to Low. Treatment options to reduce to Low risk should be
implemented as soon as practicable.
Usually acceptable to regulators. Where treatment has been required to reduce the risk to this level, ongoing maintenance is
L LOW RISK
required.
Acceptable. Manage by normal slope maintenance procedures.
VL VERY LOW RISK
Note: (7) The implications for a particular situation are to be determined by all parties to the risk assessment and may depend on the nature of the property at risk; these are only
given as a general guide.
92 Australian Geomechanics Vol 42 No 1 March 2007
Document Set ID: 24031832
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Section 36
Appendix D
General Guidelines for Hillside Development
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 37
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX G - SOME GUIDELINES FOR HILLSIDE CONSTRUCTION
GOOD ENGINEERING PRACTICE POOR ENGINEERING PRACTICE
ADVICE
GEOTECHNICAL Obtain advice from a qualified, experienced geotechnical practitioner at early Prepare detailed plan and start site works before
ASSESSMENT stage of planning and before site works. geotechnical advice.
PLANNING
SITE PLANNING Having obtained geotechnical advice, plan the development with the risk Plan development without regard for the Risk.
arising from the identified hazards and consequences in mind.
DESIGN AND CONSTRUCTION
Use flexible structures which incorporate properly designed brickwork, timber Floor plans which require extensive cutting and
or steel frames, timber or panel cladding. filling.
HOUSE DESIGN
Consider use of split levels. Movement intolerant structures.
Use decks for recreational areas where appropriate.
SITE CLEARING Retain natural vegetation wherever practicable. Indiscriminately clear the site.
ACCESS & Satisfy requirements below for cuts, fills, retaining walls and drainage. Excavate and fill for site access before
DRIVEWAYS Council specifications for grades may need to be modified. geotechnical advice.
Driveways and parking areas may need to be fully supported on piers.
EARTHWORKS Retain natural contours wherever possible. Indiscriminatory bulk earthworks.
Minimise depth. Large scale cuts and benching.
CUTS Support with engineered retaining walls or batter to appropriate slope. Unsupported cuts.
Provide drainage measures and erosion control. Ignore drainage requirements
Minimise height. Loose or poorly compacted fill, which if it fails,
Strip vegetation and topsoil and key into natural slopes prior to filling. may flow a considerable distance including
Use clean fill materials and compact to engineering standards. onto property below.
FILLS Batter to appropriate slope or support with engineered retaining wall. Block natural drainage lines.
Provide surface drainage and appropriate subsurface drainage. Fill over existing vegetation and topsoil.
Include stumps, trees, vegetation, topsoil,
boulders, building rubble etc in fill.
ROCK OUTCROPS Remove or stabilise boulders which may have unacceptable risk. Disturb or undercut detached blocks or
& BOULDERS Support rock faces where necessary. boulders.
Engineer design to resist applied soil and water forces. Construct a structurally inadequate wall such as
Found on rock where practicable. sandstone flagging, brick or unreinforced
RETAINING
Provide subsurface drainage within wall backfill and surface drainage on slope blockwork.
WALLS
above. Lack of subsurface drains and weepholes.
Construct wall as soon as possible after cut/fill operation.
Found within rock where practicable. Found on topsoil, loose fill, detached boulders
Use rows of piers or strip footings oriented up and down slope. or undercut cliffs.
FOOTINGS
Design for lateral creep pressures if necessary.
Backfill footing excavations to exclude ingress of surface water.
Engineer designed.
Support on piers to rock where practicable.
SWIMMING POOLS Provide with under-drainage and gravity drain outlet where practicable.
Design for high soil pressures which may develop on uphill side whilst there
may be little or no lateral support on downhill side.
DRAINAGE
Provide at tops of cut and fill slopes. Discharge at top of fills and cuts.
Discharge to street drainage or natural water courses. Allow water to pond on bench areas.
SURFACE Provide general falls to prevent blockage by siltation and incorporate silt traps.
Line to minimise infiltration and make flexible where possible.
Special structures to dissipate energy at changes of slope and/or direction.
Provide filter around subsurface drain. Discharge roof runoff into absorption trenches.
Provide drain behind retaining walls.
SUBSURFACE
Use flexible pipelines with access for maintenance.
Prevent inflow of surface water.
Usually requires pump-out or mains sewer systems; absorption trenches may Discharge sullage directly onto and into slopes.
SEPTIC &
be possible in some areas if risk is acceptable. Use absorption trenches without consideration
SULLAGE
Storage tanks should be water-tight and adequately founded. of landslide risk.
EROSION Control erosion as this may lead to instability. Failure to observe earthworks and drainage
CONTROL & Revegetate cleared area. recommendations when landscaping.
LANDSCAPING
DRAWINGS AND SITE VISITS DURING CONSTRUCTION
DRAWINGS Building Application drawings should be viewed by geotechnical consultant
SITE VISITS Site Visits by consultant may be appropriate during construction/
INSPECTION AND MAINTENANCE BY OWNER
OWNER’S Clean drainage systems; repair broken joints in drains and leaks in supply
RESPONSIBILITY pipes.
Where structural distress is evident see advice.
If seepage observed, determine causes or seek advice on consequences.
Australian Geomechanics Vol 42 No 1 March 2007 113
Document Set ID: 24031832
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Section 38
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
114 Australian Geomechanics Vol 42 No 1 March 2007
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 39
Appendix E
CSIRO Foundation Maintenance Guidelines
Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025
Section 40
Foundation Maintenance
and Footing Performance: BTF 18-2011
A Homeowner’s Guide
replaces
Information
Sheet 10/91
Buildings can and often do move. This movement can be up, down, lateral or rotational. The fundamental cause of movement in
buildings can usually be related to one or more problems in the foundation soil. It is important for the homeowner to identify the
soil type in order to ascertain the measures that should be put in place in order to ensure that problems in the foundation soil can
be prevented, thus protecting against building movement.
This Building Technology File is designed to identify causes of soil-related building movement, and to suggest methods of
prevention of resultant cracking in buildings.
Soil Types Erosion
The types of soils usually present under the topsoil in land zoned for All soils are prone to erosion, but sandy soil is particularly susceptible
residential buildings can be split into two approximate groups – to being washed away. Even clay with a sand component of say 10%
granular and clay. Quite often, foundation soil is a mixture of both or more can suffer from erosion.
types. The general problems associated with soils having granular
content are usually caused by erosion. Clay soils are subject to Saturation
saturation and swell/shrink problems. This is particularly a problem in clay soils. Saturation creates a bog-
like suspension of the soil that causes it to lose virtually all of its
Classifications for a given area can generally be obtained by bearing capacity. To a lesser degree, sand is affected by saturation
application to the local authority, but these are sometimes unreliable because saturated sand may undergo a reduction in volume,
and if there is doubt, a geotechnical report should be commissioned. particularly imported sand fill for bedding and blinding layers.
As most buildings suffering movement problems are founded on clay However, this usually occurs as immediate settlement and should
soils, there is an emphasis on classification of soils according to the normally be the province of the builder.
amount of swell and shrinkage they experience with variations of
water content. The table below is Table 2.1 from AS 2870-2011, the Seasonal swelling and shrinkage of soil
Residential Slab and Footing Code. All clays react to the presence of water by slowly absorbing it, making
the soil increase in volume (see table below). The degree of increase
Causes of Movement varies considerably between different clays, as does the degree of
Settlement due to construction decrease during the subsequent drying out caused by fair weather
There are two types of settlement that occur as a result of periods. Because of the low absorption and expulsion rate, this
construction: phenomenon will not usually be noticeable unless there are
• Immediate settlement occurs when a building is first placed prolonged rainy or dry periods, usually of weeks or months,
depending on the land and soil characteristics.
on its foundation soil, as a result of compaction of the soil under
the weight of the structure. The cohesive quality of clay soil The swelling of soil creates an upward force on the footings of the
mitigates against this, but granular (particularly sandy) soil is building, and shrinkage creates subsidence that takes away the
susceptible. support needed by the footing to retain equilibrium.
• Consolidation settlement is a feature of clay soil and may take
Shear failure
place because of the expulsion of moisture from the soil or because
This phenomenon occurs when the foundation soil does not have
of the soil’s lack of resistance to local compressive or shear stresses.
sufficient strength to support the weight of the footing. There are
This will usually take place during the first few months after two major post-construction causes:
construction, but has been known to take many years in
exceptional cases. • Significant load increase.
• Reduction of lateral support of the soil under the footing due to
These problems are the province of the builder and should be taken
erosion or excavation.
into consideration as part of the preparation of the site for
construction. Building Technology File 19 (BTF 19) deals with these In clay soil, shear failure can be caused by saturation of the soil
problems. adjacent to or under the footing.
GENERAL DEFINITIONS OF SITE CLASSES
Class Foundation
A Most sand and rock sites with little or no ground movement from moisture changes
S Slightly reactive clay sites, which may experience only slight ground movement from moisture changes
M Moderately reactive clay or silt sites, which may experience moderate ground movement from moisture changes
H1 Highly reactive clay sites, which may experience high ground movement from moisture changes
H2 Highly reactive clay sites, which may experience very high ground movement from moisture changes
E Extremely reactive sites, which may experience extreme ground movement from moisture changes
Notes
1. Where controlled fill has been used, the site may be classified A to E according to the type of fill used.
2. Filled sites. Class P is used for sites which include soft fills, such as clay or silt or loose sands; landslip; mine subsidence; collapsing soils; soil subject to erosion;
reactive sites subject to abnormal moisture conditions or sites which cannot be classified otherwise.
3. Where deep-seated moisture changes exist on sites at depths of 3 m or greater, further classification is needed for Classes M to E (M-D, H1-D, H2-D and E-D).
Document Set ID: 24031832
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081203 BTF 18 3pp.indd 1 25/10/12 12:40:29
Section 41
Tree root growth
Trees can cause shrinkage and damage
Trees and shrubs that are allowed to grow in the vicinity of footings
can cause foundation soil movement in two ways:
• Roots that grow under footings may increase in cross-sectional
size, exerting upward pressure on footings.
• Roots in the vicinity of footings will absorb much of the moisture
in the foundation soil, causing shrinkage or subsidence.
Unevenness of Movement
The types of ground movement described above usually occur Wall cracking
unevenly throughout the building’s foundation soil. Settlement due due to uneven
looting settlement
to construction tends to be uneven because of:
• Differing compaction of foundation soil prior to construction.
• Differing moisture content of foundation soil prior to
construction.
Movement due to non-construction causes is usually more uneven external footings. The doming is accentuated and cracking reduces
still. Erosion can undermine a footing that traverses the flow or can or disappears where it occurred because of dishing, but other cracks
create the conditions for shear failure by eroding soil adjacent to a open up. The roof lines may become convex.
footing that runs in the same direction as the flow.
Doming and dishing are also affected by weather in other ways. In
Saturation of clay foundation soil may occur where subfloor walls create areas where warm, wet summers and cooler dry winters prevail, water
a dam that makes water pond. It can also occur wherever there is a migration tends to be toward the interior and doming will be
source of water near footings in clay soil. This leads to a severe accentuated, whereas where summers are dry and winters are cold
reduction in the strength of the soil which may create local shear failure. and wet, migration tends to be toward the exterior and the
Seasonal swelling and shrinkage of clay soil affects the perimeter of underlying propensity is toward dishing.
the building first, then gradually spreads to the interior. The swelling
process will usually begin at the uphill extreme of the building, or on Movement caused by tree roots
the weather side where the land is flat. Swelling gradually reaches the In general, growing roots will exert an upward pressure on footings,
interior soil as absorption continues. Shrinkage usually begins where whereas soil subject to drying because of tree or shrub roots will tend
the sun’s heat is greatest. to remove support from under footings by inducing shrinkage.
Effects of Uneven Soil Movement on Structures Complications caused by the structure itself
Most forces that the soil causes to be exerted on structures are
Erosion and saturation vertical – i.e. either up or down. However, because these forces are
Erosion removes the support from under footings, tending to create seldom spread evenly around the footings, and because the building
subsidence of the part of the structure under which it occurs. resists uneven movement because of its rigidity, forces are exerted
Brickwork walls will resist the stress created by this removal of from one part of the building to another. The net result of all these
support by bridging the gap or cantilevering until the bricks or the forces is usually rotational. This resultant force often complicates the
mortar bedding fail. Older masonry has little resistance. Evidence of diagnosis because the visible symptoms do not simply reflect the
failure varies according to circumstances and symptoms may include: original cause. A common symptom is binding of doors on the
• Step cracking in the mortar beds in the body of the wall or above/ vertical member of the frame.
below openings such as doors or windows.
• Vertical cracking in the bricks (usually but not necessarily in line Effects on full masonry structures
with the vertical beds or perpends). Brickwork will resist cracking where it can. It will attempt to span
areas that lose support because of subsided foundations or raised
Isolated piers affected by erosion or saturation of foundations will points. It is therefore usual to see cracking at weak points, such as
eventually lose contact with the bearers they support and may tilt or openings for windows or doors.
fall over. The floors that have lost this support will become bouncy,
In the event of construction settlement, cracking will usually remain
sometimes rattling ornaments etc.
unchanged after the process of settlement has ceased.
Seasonal swelling/shrinkage in clay With local shear or erosion, cracking will usually continue to develop
Swelling foundation soil due to rainy periods first lifts the most exposed until the original cause has been remedied, or until the subsidence
extremities of the footing system, then the remainder of the perimeter has completely neutralised the affected portion of footing and the
footings while gradually permeating inside the building footprint to lift structure has stabilised on other footings that remain effective.
internal footings. This swelling first tends to create a dish effect, In the case of swell/shrink effects, the brickwork will in some cases
because the external footings are pushed higher than the internal ones. return to its original position after completion of a cycle, however it
The first noticeable symptom may be that the floor appears slightly is more likely that the rotational effect will not be exactly reversed,
dished. This is often accompanied by some doors binding on the and it is also usual that brickwork will settle in its new position and
floor or the door head, together with some cracking of cornice will resist the forces trying to return it to its original position. This
mitres. In buildings with timber flooring supported by bearers and means that in a case where swelling takes place after construction
joists, the floor can be bouncy. Externally there may be visible and cracking occurs, the cracking is likely to at least partly remain
dishing of the hip or ridge lines. after the shrink segment of the cycle is complete. Thus, each time the
As the moisture absorption process completes its journey to the cycle is repeated, the likelihood is that the cracking will become
innermost areas of the building, the internal footings will rise. If the wider until the sections of brickwork become virtually independent.
spread of moisture is roughly even, it may be that the symptoms will With repeated cycles, once the cracking is established, if there is no
temporarily disappear, but it is more likely that swelling will be other complication, it is normal for the incidence of cracking to
uneven, creating a difference rather than a disappearance in stabilise, as the building has the articulation it needs to cope with the
symptoms. In buildings with timber flooring supported by bearers problem. This is by no means always the case, however, and monitoring
and joists, the isolated piers will rise more easily than the strip of cracks in walls and floors should always be treated seriously.
footings or piers under walls, creating noticeable doming of flooring. Upheaval caused by growth of tree roots under footings is not a
As the weather pattern changes and the soil begins to dry out, the simple vertical shear stress. There is a tendency for the root to also
external footings will be first affected, beginning with the locations exert lateral forces that attempt to separate sections of brickwork
where the sun’s effect is strongest. This has the effect of lowering the after initial cracking has occurred.
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Section 42
The normal structural arrangement is that the inner leaf of • Corroded guttering or downpipes can spill water to ground.
brickwork in the external walls and at least some of the internal walls • Downpipes not positively connected to a proper stormwater
(depending on the roof type) comprise the load-bearing structure on collection system will direct a concentration of water to soil that is
which any upper floors, ceilings and the roof are supported. In these directly adjacent to footings, sometimes causing large-scale
cases, it is internally visible cracking that should be the main focus of problems such as erosion, saturation and migration of water under
attention, however there are a few examples of dwellings whose the building.
external leaf of masonry plays some supporting role, so this should be
checked if there is any doubt. In any case, externally visible cracking Seriousness of Cracking
is important as a guide to stresses on the structure generally, and it
should also be remembered that the external walls must be capable of In general, most cracking found in masonry walls is a cosmetic
supporting themselves. nuisance only and can be kept in repair or even ignored. The table
below is a reproduction of Table C1 of AS 2870-2011.
Effects on framed structures AS 2870-2011 also publishes figures relating to cracking in concrete
Timber or steel framed buildings are less likely to exhibit cracking due floors, however because wall cracking will usually reach the critical
to swell/shrink than masonry buildings because of their flexibility. point significantly earlier than cracking in slabs, this table is not
Also, the doming/dishing effects tend to be lower because of the reproduced here.
lighter weight of walls. The main risks to framed buildings are
encountered because of the isolated pier footings used under walls. Prevention/Cure
Where erosion or saturation causes a footing to fall away, this can
double the span which a wall must bridge. This additional stress can Plumbing
create cracking in wall linings, particularly where there is a weak Where building movement is caused by water service, roof
point in the structure caused by a door or window opening. It is, plumbing, sewer or stormwater failure, the remedy is to repair the
however, unlikely that framed structures will be so stressed as to suffer problem. It is prudent, however, to consider also rerouting pipes
serious damage without first exhibiting some or all of the above away from the building where possible, and relocating taps to
symptoms for a considerable period. The same warning period should positions where any leakage will not direct water to the building
apply in the case of upheaval. It should be noted, however, that where vicinity. Even where gully traps are present, there is sometimes
framed buildings are supported by strip footings there is only one leaf sufficient spill to create erosion or saturation, particularly in modern
of brickwork and therefore the externally visible walls are the installations using smaller diameter PVC fixtures. Indeed, some
supporting structure for the building. In this case, the subfloor gully traps are not situated directly under the taps that are installed
masonry walls can be expected to behave as full brickwork walls. to charge them, with the result that water from the tap may enter
the backfilled trench that houses the sewer piping. If the trench has
Effects on brick veneer structures been poorly backfilled, the water will either pond or flow along the
Because the load-bearing structure of a brick veneer building is the bottom of the trench. As these trenches usually run alongside the
frame that makes up the interior leaf of the external walls plus footings and can be at a similar depth, it is not hard to see how any
perhaps the internal walls, depending on the type of roof, the water that is thus directed into a trench can easily affect the
building can be expected to behave as a framed structure, except that foundation’s ability to support footings or even gain entry to the
the external masonry will behave in a similar way to the external leaf subfloor area.
of a full masonry structure.
Ground drainage
Water Service and Drainage In all soils there is the capacity for water to travel on the surface and
below it. Surface water flows can be established by inspection during
Where a water service pipe, a sewer or stormwater drainage pipe is in and after heavy or prolonged rain. If necessary, a grated drain system
the vicinity of a building, a water leak can cause erosion, swelling or connected to the stormwater collection system is usually an easy
saturation of susceptible soil. Even a minuscule leak can be enough to solution.
saturate a clay foundation. A leaking tap near a building can have the
same effect. In addition, trenches containing pipes can become It is, however, sometimes necessary when attempting to prevent water
watercourses even though backfilled, particularly where broken migration that testing be carried out to establish watertable height
rubble is used as fill. Water that runs along these trenches can be and subsoil water flows. This subject is referred to in BTF 19 and
responsible for serious erosion, interstrata seepage into subfloor areas may properly be regarded as an area for an expert consultant.
and saturation.
Protection of the building perimeter
Pipe leakage and trench water flows also encourage tree and shrub It is essential to remember that the soil that affects footings extends
roots to the source of water, complicating and exacerbating the well beyond the actual building line. Watering of garden plants,
problem. Poor roof plumbing can result in large volumes of rainwater shrubs and trees causes some of the most serious water problems.
being concentrated in a small area of soil:
For this reason, particularly where problems exist or are likely to
• Incorrect falls in roof guttering may result in overflows, as may occur, it is recommended that an apron of paving be installed around
gutters blocked with leaves etc. as much of the building perimeter as necessary. This paving should
CLASSIFICATION OF DAMAGE WITH REFERENCE TO WALLS
Approximate crack width Damage
Description of typical damage and required repair limit (see Note 3) category
Hairline cracks <0.1 mm 0
Fine cracks which do not need repair <1 mm 1
Cracks noticeable but easily filled. Doors and windows stick slightly. <5 mm 2
Cracks can be repaired and possibly a small amount of wall will need to be 5–15 mm (or a number of cracks 3
replaced. Doors and windows stick. Service pipes can fracture. Weathertightness 3 mm or more in one group)
often impaired.
Extensive repair work involving breaking-out and replacing sections of walls, 15–25 mm but also depends on 4
especially over doors and windows. Window and door frames distort. Walls lean number of cracks
or bulge noticeably, some loss of bearing in beams. Service pipes disrupted.
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The text continues on section 43.