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Geotechnical Investigation Report · OPW26/0149
Geotechnical Investigation Report
PTG/04982 – 0001 – Rev0
Proposed Bimbimbie Cabins
87 Hayward Road, Lake MacDonald
25 August 2026
www.ptgconsulting.com.au
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REPORT DETAILS Unique Document Identification Document Title Geotechnical Investigation Report – Proposed Bimbimbie Cabins Project Number PTG/04982 Document ID PTG/04982 – 0001 – Rev0 Client SCG Consulting Engineers Client Contact Tom Harrington PTG Office Details Location Sunshine Coast Address U2/9-13 Matheson Street, Baringa, QLD, 4551 Telephone 1300 911 304 Email [email protected] Web www.ptgconsulting.com.au Revision Details Revision No. Date Comments 0 25 August 2026 Final Document Approval Written By: Reviewed By: Approved By: Paul Hardcastle Luke Goodluck Justin Taing Principal Engineering Geologist Branch Lead - Geotechnical Sunshine Coast Regional Director – Geotechnical p | (07) 5647 0457 p | (07) 5647 0457 p | (07) 5647 0457 e | [email protected] e | [email protected] e | [email protected]
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1 REPORT SCOPE 4
2 SITE DESCRIPTION 4
3 PROPOSED DEVELOPMENT 5
CONTENTS
4 REGIONAL GEOLOGY 6
5 FIELD INVESTIGATION 7
6 GEOTECHNICAL MODEL 7
6.1 Encountered Strata 7
6.2 Groundwater 8
7 LABORATORY TESTING AND RESULTS 8
8 SLOPE STABILITY ANALYSIS 9
9 GEOTECHNICAL RECOMMENDATIONS 11
9.1 SITE CLASSIFICATION 11
9.2 Earthworks Advice 11
9.2.1 Excavation Conditions 11
9.2.2 Suitability of Site Won Material 11
9.2.3 Site Formation Recommendations 12
9.2.4 Filling 12
9.2.5 General Dam Construction Advice 12
9.2.6 Batter Angles 13
9.3 FOUNDATION RECOMMENDATIONS 13
9.4 STORMWATER/WASTEWATER EFFLUENT DISPOSAL 13
9.5 CONSTRUCTION OBSERVATIONS 14
10 LIMITATIONS 14
TABLES
Table 1: Summary of Material Depths Encountered in Boreholes ...................................................................................8
Table 2: Summary of Atterberg Limits Testing ......................................................................................................................8
Table 3: Summary of Shrink-Swell Index Testing ..................................................................................................................8
Table 4: Summary of Emerson Class Testing..........................................................................................................................9
Table 5: Summary of CBR Testing .............................................................................................................................................9
Table 6: Geotechnical parameters utilised in analysis. ..................................................................................................... 10
Table 7: Summary of Global Stability Analysis. ................................................................................................................... 10
Table 8: Shallow Pier Allowable Bearing Pressures ............................................................................................................ 13
APPENDICES
Appendix 1 Test Location Plan & Borehole Logs
Appendix 2 Laboratory Testing
Appendix 3 Slope Stability Analysis Results
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1 REPORT SCOPE
This report presents the results of the geotechnical investigation carried out by PTG Consulting (PTG) for the
proposed Bimbimbie cabins at 87 Hayward Road, Lake MacDonald. The investigation was commissioned by Tom
Harrington on behalf of SCG Consulting Engineers (SCG) for their client, Fiona Buchanan.
The purpose of the investigation was to explore the ground conditions in the location of the proposed cabins and
proposed farm dam. This report includes a description of the fieldwork procedures, details the results of the fieldwork
and laboratory testing, presents the results of slope stability analyses performed, and provides information on the
following:
» A summary of the subsurface conditions including regional geology and groundwater conditions;
» Founding conditions for the cabins;
» Earthworks recommendations for the dam; and,
» General development recommendations.
2 SITE DESCRIPTION
The overall site is rural residential property that is legally described as Lot 5 on RP209009 which has a total plan area
of 8.07 ha. It is bound by Hayward Road to the north, Lake MacDonald to the west, and other rural residential
properties to the south and east. The property is approximately rectangular in plan shape, with the long axis parallel
to Hayward Road. Our investigation was focused toward the eastern boundary, and this area is hereinafter referred to
as the investigation area. An aerial image showing the overall site relative to Hayward Road and the surrounding
properties, with the investigation area highlighted, is shown below in Figure 1.
Figure 1. Extract from Queensland Globe 1 showing aerial photo and overall site cadastral boundaries relative to Hayward Road and
surrounding properties. The approximate investigation area is highlighted by the red circle. Not to scale.
At the time of the fieldwork, the investigation area comprised maintained grassed areas with occasional trees. Access
to the site consisted of an unpaved track stemming from the main site entrance on Hayward Road. No structures were
present within the investigation area.
1 Queensland Government. (n.d.). Queensland Globe. https://qldglobe.information.qld.gov.au
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The topography within the investigation area is defined by a ridgeline that enters the site at the southern boundary
and is trending northwest. As a result, much of the land within the investigation area comprises the northeast flank of
the ridge, and is gently to moderately sloping at grades of between 1(v):6(h) to 1(v):4(h), as indicated in Figure 2
below.
Figure 2. Extract from Queensland Globe1 with a focus on the investigation area within the overall site, showing aerial photo, parts of overall
site cadastral boundaries, and LiDAR contours. Not to scale.
3 PROPOSED DEVELOPMENT
From the information provided 2 3, it is understood that the proposed development will comprise three separate cabins
with associated, stand-alone carport structures, and a dam.
The drawings show the cabins to be located near the crest of the ridge, just downslope of the existing access track.
Some minor earthworks, mostly in the form of excavation, will be undertaken ahead of the cabin and car port
construction, however no specific areas, or volumes of cut or fill are provided. Additionally, the drawings show the
cabins will make use of suspended floors supported on shallow pier foundations, while the car ports will utilise a
concrete slab on grade. The Site Plan drawing suggests Cabins 2 and 3 will have an associated 20,000 L rainwater
tank for domestic reuse, but that Cabin 1 will not. Despite what is shown on the drawing, it is assumed that Cabin 1
will also have the same water tank associated with it.
The dam is shown downslope, to the northeast of the cabins, and we understand that it is intended to be formed via a
combination of cut to fill earthworks. The drawings show cut and fill volumes of 946 m³ and 1,004 m³ respectively,
leaving a shortfall of 58 m³. It is assumed that the shortfall will be made up of either material won from the formation
works for the cabins, or will be imported from an off-site borrow source. Both cut and fill slopes formed to create the
dam are shown to be finished at a grade of 1(v):3(h), with the dam having a crest width of 3 m. The extent of the
proposed development is shown in Figure 3 and Figure 4 below.
2 Courtesy Pty Ltd (2026, April). Bimbimbie Cabins, Bill & Fiona Buchanan, 87 Hayward Road, Lake MacDonald. QLD. 4563. Project
No. 003. Drawing Nos. 1.1, 2.1, 2.2, 3.3.1 and 3.3.2, Revision 2.
3 Bax Engineering Pty Ltd (2026, July). Bimbimbie Cabins, 87 Hayward Rd, Lake MacDonald QLD 4563. Project No. 146-019. Drawing
Nos 001, 002, 100, 200, 201, 250, 251, 252, 253 & 300.
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Figure 3: Extract of Courtesy drawing 2.2. Not to scale. North arrow not provided.
Figure 4. Extract of Bax Engineering drawing 200. Not to scale.
4 REGIONAL GEOLOGY
Reference to the online Queensland Geotechnical Database online geology map 4 indicates that the investigation area
is underlain by Middle Triassic aged Kin Kin beds, as per Figure 5 below.
4 Geological Survey of Queensland. (n.d.). QGD Map. https://qgd.org.au/map?satellite=true&layer=geology#17.12/-
27.458669/153.038142
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Figure 5. Excerpt from the Queensland Geotechnical Database geologic map approximately centred on the overall site. Not to scale.
Chapter 5 within The Geology of Queensland 5 describes the Kin Kin Beds as comprising metasiltstone, metashale,
phyllite, fine-grained turbidite with slaty crenulation cleavage. It is considered to be equivalent to the Brooweena
Formation on Maryborough, with the main similarities being redbeds and conglomerates with Early Triassic marine
fossils present, although the Kin Kin beds are more deformed and have a slightly higher metamorphic grade.
5 FIELD INVESTIGATION
The fieldwork included the drilling of three (3) boreholes (designated as BH01 to BH03) on 21 July 2026 in the
approximate locations shown on our Test Location Plan presented in Appendix 1.
The boreholes were drilled using a ute-mounted drilling rig with a tungsten carbide tipped solid flight auger. The arising
in each borehole was classified and logged in accordance with AS1726:2017 by an experienced geotechnical driller
from PTG Consulting.
The soil consistency and relative density described on the borehole logs were inferred from the DCP results, tactile
assessment and published correlations.
The logs of the borehole reports are presented in Appendix 1.
6 GEOTECHNICAL MODEL
6.1 Encountered Strata
The subsurface ground conditions encountered are briefly described below, with depth information summarised in
Table 1. For a full detailed description of the subsurface conditions encountered, reference should be made to the
borehole log reports presented in Appendix 1.
Natural soil, consisting of silty CLAY was identified from ground surface in all boreholes. The soil was generally logged
as being of medium plasticity to high plasticity, with DCP results indicating the soil was generally very stiff to hard,
with strength generally increasing with depth.
5 Jell, P. A. (Ed.). (2013). Geology of Queensland. Geological Survey of Queensland.
https://geoscience.data.qld.gov.au/dataset/cr145752
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Table 1: Summary of Material Depths Encountered in Boreholes
Strata BH01 BH02 BH03
Firm to Stiff silty CLAY 0.0 – 1.3 n/a n/a
Stiff to Very Stiff silty
n/a 0.0 – 1.5 0.3 – 1.0
CLAY
Very Stiff to Hard silty
n/a n/a 0.0 – 0.3
CLAY
Hard silty CLAY 1.3 – 6.0 1.5 – 6.0 1.0 – 6.0
Notes:
a. All depths shown are in metres below ground level
b. n/a = material not encountered
c. Values in bold indicate borehole termination depth
Notably, our investigation did not encounter any pre-existing, non-engineered fill.
6.2 Groundwater
Groundwater was not encountered in any of the boreholes. It should be noted that groundwater levels can be perched,
and/or can fluctuate seasonally, and also during and after heavy/prolonged rainfall events. Given this natural
variability, it is prudent to assume that water levels can fluctuate.
7 LABORATORY TESTING AND RESULTS
NATA accredited laboratory testing was undertaken on selected representative soil samples recovered from the
boreholes in accordance with ‘AS1289-Methods of Testing Soils for Engineering Purposes’. The purpose of the
laboratory testing was to determine typical soil and rock behaviour characteristics for engineering assessment. Copies
of the laboratory reports are presented in Appendix 3; the results of the testing are summarised in Table 2, Table 3,
Table 4, and Table 5 below.
Table 2: Summary of Atterberg Limits Testing
Borehole
Depth (m) Material WL (%) WP (%) IP (%) LS (%)
No.
BH02 0.3 – 1.6 Silty CLAY 69 30 39 12
BH03 0.4 – 1.0 Silty CLAY 45 21 24 9
Notes:
• WL = Liquid limit; Wp = Plastic limit; Ip = Plasticity index; LS = Linear shrinkage
Table 3: Summary of Shrink-Swell Index Testing
Borehole Shrinkage
Depth (m) Material IMC(%) FMC (%) Iss (%)
No. (%)
BH01 0.6 – 1.2 Silty CLAY 21.4 33.2 26.2 1.9
BH02 0.5 – 1.2 Silty CLAY 24.6 27.0 23.7 1.1
Notes:
• IMC = Initial Moisture Content
• FMC = Final Moisture Content
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Table 4: Summary of Emerson Class Testing
Borehole No. Depth (m) Material Emerson Class No.
BH01 0.3 – 1.3 Silty CLAY 6
BH02 3.0 – 4.5 Silty CLAY 6
BH03 1.0 – 1.5 Silty CLAY 5
Notes:
• Class 1 = Complete Dispersion
• Class 2 = Some Dispersion
• Class 3 = Dispersion after remoulding
• Class 4 = No dispersion (calcite or gypsum present)
• Class 5 = Dispersion after soil water suspension
• Class 6 = Flocculation
• Class 7 = Swelling (not slaking)
• Class 8 = Not swelling (not slaking)
Table 5: Summary of CBR Testing
Borehole Depth MDD
Material FMC (%) CMC (%) OMC (%) Swell (%) CBR (%)
No. (m) (t/m3)
Silty
BH03 0.5-1.5 26.0 26.0 25.9 1.55 0.0 4.5
CLAY
Notes:
• FMC = Field Moisture Content
• CMC = Compaction Moisture Content
• OMC = Optimum Moisture Content
• MDD = Maximum Dry Density
8 SLOPE STABILITY ANALYSIS
A global stability analysis has been undertaken in the location of the proposed dam. To undertake the analysis, we
have generated a representative cross section (Section A) as shown on the Test Location Plan presented in Appendix
1. This location was chosen as it both mirrors Section A as per the Bax Engineering drawing set, and also captures the
natural ground profile and proposed cut to fill depths through the location of the dam and associated pond.
In undertaking our analyses, we have assessed both the existing ground profile, and the proposed ground profile. The
existing profile was derived from contour information shown on the drawing sets provided, and cross-checked against
Digital Terrain Model (DTM) information which was obtained from the online Elvis webservice 6 . The proposed
development drawings show the maximum depth of cut will be in the order of 2.5 m, while the maximum thickness of
fill will be approximately 3.0 m. The maximum water level within the pond will be 2 m, which coincides with the crest
of the bund.
To generate the subsurface profile the nearby results from our investigation (BH02 and BH03) were transposed on to
Section A. These boreholes generally suggest two in situ engineering units in this location: stiff to very stiff residual
silty CLAY overlying hard silty CLAY. No denser or higher strength material was encountered within the limit of our
investigation (6 m depth) which would allow the generation of a third, higher strength horizon at depth. Instead, the
slope stability models have been constrained at approximately 12 m depth (double the investigation depth) to provide
a limit to the base of the stability models and limit the formation of improbably deep/long failure surfaces.
6 Geoscience Australia. (n.d.). ELVIS – Elevation and depth (Foundation Spatial Data Framework). https://elevation.fsdf.org.au/
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Whilst groundwater was not encountered in our investigation, we have modelled an assumed phreatic surface at
approximately 7 m depth. Additional analyses have also been undertaken to model a hypothetical, elevated
groundwater condition to simulate a potential rise in groundwater following a period of prolonged, intense rainfall. For
the elevated groundwater models, the phreatic surface is modelled at a depth of approximately 3 m.
Further to the above, we have undertaken two further scenarios of the proposed profile: soon after construction, before
the pond is filled, and shortly after construction as soon as the pond has been filled.
The geotechnical parameters for the modelled units have been interpolated from the borehole logs and laboratory test
results. Geotechnical parameters for the proposed fill material have been assumed. All geotechnical parameters used
in our analyses are summarised in Table 6 below.
Table 6: Geotechnical parameters utilised in analysis.
Undrained
Drained Parameters
Unit Weight Parameters
Material
γ (kN/m³)
Cohesion Friction Shear Strength
c’ (kPa) Ø’ (deg) su (kPa)
1 – St – Vst Silty CLAY (Natural) 18 5 23 20
2 – H Silty CLAY (Natural) 18 6 25 60
3 – Vst – H Silty CLAY (Fill) 18 5 20 50
Drained parameters were adopted for long-term stability assessments, while undrained parameters were utilised for
the short-term stability cases, i.e., shortly after the dam has been constructed. The undrained parameters were
selected as conservative lower-bound values to help bound the short-term risk in the loading scenarios analysed.
The analyses were undertaken using the Slide2 software by RocScience and were conducted using the Spencer
method for interslice forces. Analyses were undertaken for both circular and non-circular failure surfaces, using the
Auto Refine and Cuckoo search methods respectively. Additionally, the non-circular analyses were optimised to refine
the returned Factor of Safety (FoS) value within the search areas defined.
For the assumed groundwater profiles, a minimum Factor of Safety (FoS) of 1.5 was targeted for long term stability.
For the hypothetical, elevated groundwater scenarios, a minimum FoS of 1.3 was targeted. The results of the global
stability assessment are summarised in Table 7, with outputs of the analyses presented in Appendix 3.
Table 7: Summary of Global Stability Analysis.
Circular Non-Circular
Scenario Pond Level Groundwater Parameter Set
Surface Surface
Existing Profile n/a Assumed Drained 2.9 2.9
Existing Profile n/a Raised Drained 2.3 2.3
Proposed Profile Full Assumed Drained 1.8 1.8
Proposed Profile Full Raised Drained 1.7 1.7
Proposed Profile Empty Assumed Undrained 3.3 2.9
Proposed Profile Empty Raised Undrained 3.3 2.9
Proposed Profile Full Assumed Undrained 3.1 2.6
Proposed Profile Full Raised Undrained 3.1 2.6
Based on the geometry and geotechnical parameters adopted, the analyses indicate that the proposed dam and
associated pond is expected to remain stable through all loading scenarios analysed.
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We point out that the analyses have been undertaken assuming the earthworks for the development are carried out
in adherence, or in excess of the recommendations provided in Section 9 below. In this respect, construction
observations and confirmation of site preparatory work and fill placement is recommended. Where the works are not
undertaken in accordance with the provided development recommendations, the short-term and long-term FoS for
the stability of the proposed dam is likely to differ from the values presented in Table 7, to the point where
unfavourable FoS values that could lead to failure of the dam are possible.
We also point out that the analyses check for global stability only. Other dam related stability concerns, such as piping
erosion, have not been assessed as this is beyond the programming of the Slide2 software.
9 GEOTECHNICAL RECOMMENDATIONS
The geotechnical recommendations presented herein are based on the factual information collected during the
fieldwork, the results of the laboratory testing, the results of the slope stability analyses undertaken, geotechnical
engineering best practice, local experience and published literature. Irrespective, the recommendations provided are
still, fundamentally, an opinion.
In summary, the ground conditions that are likely to be encountered at the site can be characterised as comprising a
residual soil consisting of stiff to hard silty CLAY. Pre-existing fill materials are not anticipated in any notable quantity,
and none were encountered in our investigation.
Based on the ground conditions, it is likely that the most suitable foundation system for the buildings would comprise
shallow piers supported in the near surface residual soils, designed in general accordance with AS2870:2011.
9.1 SITE CLASSIFICATION
Based on the subsurface conditions encountered during the investigation, the site is considered to comprise naturally
occurring fine-grained soils with a low to moderate shrink–swell potential. The site is assessed to be subject to normal
site moisture conditions in accordance with AS2870.
The site investigation did not identify the presence of uncontrolled fill, existing structures, significant vegetation
influences, or other abnormal site conditions that would warrant a Class ‘P’ classification under Clause 2.1.3 of
AS2870.
The characteristic ground surface movement (Ys) value in the location of the proposed cabins has been determined
from the results of shrink–swell index (Iss) value returned from BH01, which suggests a characteristic ground surface
movement a in the order of 20 mm to 40 mm as per AS2870:2011. This level of ground movement is consistent with
a Site Class ‘M’ (moderately reactive clay site) in accordance with AS2870:2011.
It should be noted that the site classification does not include any tree effects, or any existing or future filling works,
which may result in increased ground movements.
This classification is applicable to sites subject to normal moisture conditions. Changes to site conditions, such as the
introduction or removal of trees, poor drainage, or development of gardens adjacent to footings, may result in
increased ground movements and potential structural damage.
9.2 Earthworks Advice
9.2.1 Excavation Conditions
Excavation of the residual soils could be achieved using excavators of any size. As a rule of thumb, refusal for a ute
mounted drill rig with 100 mm augers is generally the depth where a 30-tonne excavator fitted with a 600 mm wide
bucket and tiger teeth will encounter bucket refusal.
9.2.2 Suitability of Site Won Material
With the exception of any topsoil or materials containing notable organic inclusions, most of the materials won from
the site excavations are expected to be suitable for reuse as structural for the dam. Provided that there are no
limitations on fill (i.e., shrink-swell, CBR, WPI), site materials could be considered suitable for reuse as structural fill
for the dam.
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9.2.3 Site Formation Recommendations
The site formation works to be carried out should include appropriate controls to protect batter slopes and exposed
work areas from concentrated stormwater flows. Bunding or diversion channels should be employed to ensure any
water from rainfall events during construction can be directed to appropriate locations and managed accordingly.
9.2.4 Filling
The fill for the dam should be placed and compacted under Level 1 inspection and testing in accordance with site
specific design drawings and specifications. Minimum earthwork requirements should be in accordance with
‘AS3798–2007 Guidelines on Earthworks for Commercial and Residential Developments’. In summary, AS3798
guidelines recommend the following:
» Strip vegetation and uncontrolled fill (if any);
» Test rolling using the following plant and load conditions:
o A static smooth steel wheeled roller with a mass not less than 12 tonne and a load intensity under a wheel load
not less than 6 tonnes;
o A pneumatic tyred plant with a mass not less than 20 tonnes and a ground pressure not less than 450 kPa per
tyre; or,
o A highway truck with rear axle loaded not less than 8 tonnes with tyres inflated to 550 kPa;
» Subject to site specific conditions, any soft areas identified might need to be removed and replaced with select
material;
» Prior to placing any fill, the existing ground surface should be cut into near horizontal benches, with each bench
having a slight ‘back-fall’ into the slope. The material won from the benching may be set-aside, and re-used during
the bulk filling;
» Structural fill should be laid and compacted in near horizontal layers, commonly termed ‘lifts’, with each lift
generally not to exceed 300 mm uncompacted thickness;
» Structural fill for the dam should be compacted to a 100% minimum dry density ratio (DDR), with a moisture
content variation not exceeding either -2% or + 5% of the optimum moisture content (OMC). This requirement
should result in the majority of the fill being compacted slightly wet of optimum; and,
» All fill to be utilised for the dam must comprise fine-grained, cohesive material only; granular soils with a sand
content greater than 30% and/or a gravel content greater than 20% are not appropriate and can lead to increased
permeability of the dam structure.
Other earthwork considerations include:
» Over-compacted clay soils can be prone to future softening if subject to seepage, potentially compromising the
long-term integrity of the embankment, and should be avoided;
» The most suitable plant for compaction is a pad-foot roller for cohesive soils with varying amounts of silt and clay;
and,
» Any overly wet soils would need to be dried out before reuse or continuation of earthworks. Drying of in situ wet
soils is accelerated by tyning the upper 0.1 m to 0.3 m depth and baking-out (to within -2% to +5% of the OMC
value) during sunny weather.
PTG can provide Level 1 supervision and testing following site specific design drawings and specifications and AS
3798–2007 if required.
9.2.5 General Dam Construction Advice
In addition to the pond outlet that will help maintain the pond at the target level, it is recommended that the dam
construction include a secondary, emergency spillway. The emergency spillway is recommended to help minimise
uncontrolled over-topping of the dam should the primary outlet become blocked, or when the influx of water into the
pond exceeds the flow-rate of the outlet. If the emergency spillway were to be activated, the volume and rate of water
discharge has the potential to be significant. As such the emergency spillway is recommended to be specifically
armoured to prevent scour of the dam structure and the land below in the event that it ever becomes activated.
Armouring may include, but should not be considered limited to:
» Geotextile surface matting to help stabilise surficial soils;
» Specific erosion matting where discharge velocities and volumes are anticipated to be significant during over-
topping events;
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» Rock armouring with angular, inert rocks of sufficient mass such that they will not be mobilised or entrained by
the discharge flow during over-topping events; and,
» Reinforced concrete armouring with engineer designed baffles to help retard and slow the velocity of any
discharged water.
As part of the addition of an emergency spillway, it is recommended that the dam height be increased to provide
additional free-board above the designed pond level. The additional free-board will help to reduce the potential for
over-topping, and also help to direct water towards the emergency spillway during extreme weather events.
9.2.6 Batter Angles
Temporary cut batter angles of 1(v):1(h), or 45°, may be achievable for unsurcharged batters up to 2.0m high where
no groundwater is present. Where surcharges are located within H (height of the batter) of the top of the batter, or
where the excavation extends below the groundwater table, some reduction in this angle will be required.
Care must be taken with unsupported batters to ensure no adjacent structures or services are undermined. Structures
or services are to be set back behind the crests of unsupported batters to a minimum horizontal distance of at least
1.5 times the depth of excavation.
Permanent batter slopes formed in filled ground should be over-filled beyond the intended batter position to ensure
adequate and uniform compaction. Once the over-fill is complete, the final batter should be formed by excavating out
the excess material.
Permanent batter faces formed in both cut and filled ground should be finished at a grade that is no steeper 1(v):3(h),
or 18°.
9.3 FOUNDATION RECOMMENDATIONS
The investigation undertaken generally indicates competent founding conditions in the location of the proposed
cabins. Shallow piers for the cabins may be designed in general accordance with AS2870:2011 for Class M reactive
soil conditions and the structural loads from the cabins.
In general, borehole BH01 suggests firm to stiff ground conditions are present within 1 m of present ground surface,
however we are also aware that some initial site formation excavation will take place ahead of the cabin foundations
construction. For the preliminary design of the shallow piers for the cabins, the allowable bearing pressures provided
in Table 8 are recommended:
Table 8: Shallow Pier Allowable Bearing Pressures
Material Type Allowable Bearing Pressure (kPa)
Firm to Stiff Silty CLAY 50 – 150
Stiff to Very Stiff Silty CLAY 150 – 250
Very Stiff to Hard Silty CLAY 250 – 450
Hard Silty CLAY 450+
Higher values may be adopted subject to verification of founding conditions at the time of construction.
Given the relatively light loads from the cabins and the competent founding materials present, total settlements are
expected to be small (typically <10-15 mm). Differential settlement across individual cabin footprints is expected to
be negligible where founding levels are consistent.
The carport slabs should be designed as conventional stiffened raft slab in accordance with AS2870:2011 for Class M
reactive soil conditions. Similarly, the raft slabs may be designed assuming an allowable bearing pressure of 100 kPa
where founding upon stiff to very stiff residual clay
Provided slabs are constructed at uniform founding levels and within natural materials only, or a combination of
engineer certified Level 1 fill and natural materials, significant differential settlement is not anticipated.
9.4 STORMWATER/WASTEWATER EFFLUENT DISPOSAL
Stormwater and wastewater effluent disposal was outside the scope of our brief, and we understand these matters
will be addressed by others. As a general comment, however, we are of the opinion that the near surface soils are
likely to be of low permeability, and therefore would be unsuitable for any form of soakage disposal system for either
stormwater or treated wastewater effluent.
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Due to the low permeability of the site soils, it is recommended to use a package wastewater treatment plant with
final effluent being pumped to a disposal field comprising dripper lines within a specifically designated area.
Stormwater from roofs and hard standings that is not captured for re-use should be directed to safe discharge
locations that are away from the new cabins, and downslope of any steeply sloping areas. Stormwater may be
discharged to the dam pond, but should be attenuated to avoid shocking the pond with sudden discharge volumes
which could overwhelm the primary discharge point. Where excess stormwater is not directed to the pond, it should
not be allowed to discharge directly on to the ground surface in an uncontrolled manner as this could result in softening
of the soil, scour erosion and/or unintended slope instability issue.
9.5 CONSTRUCTION OBSERVATIONS
In order to confirm the assumptions and recommendations made in formulating this report, we recommend that a
Registered Engineer who is both experienced in the field of soil mechanics, and who is also familiar with the contents
of this report, be retained in order to inspect the ground conditions at the time of the site formation works and
foundation/retaining wall construction. Should the ground conditions be found to be markedly different to those
encountered during our investigation, provision should be made for amending the foundation and retaining designs as
determined necessary by the inspecting engineer in agreement with the structural engineer for the project.
10 LIMITATIONS
PTG Consulting has prepared this report (or services) for this project in accordance with PTG's proposal and
acceptance received from the Client. These limitations apply whether the report was created under PTG’s own terms
and conditions or otherwise.
This report is provided for the exclusive use of the SCG Consulting Engineers for the Geotechnical scope of works at
87 Hayward Road, Lake MacDonald. The report should not be used by or relied upon for other projects or purposes
on the same or other site or by a third party. Any party so relying upon this report beyond its exclusive use and purpose
as stated above, and without the express written consent of PTG, does so entirely at its own risk and without recourse
to PTG for any loss or damage. In preparing this report, PTG has necessarily relied upon information provided by the
client and/or their agents.
PTG's advice is based on information gained from limited subsurface excavations and sampling supplemented by
knowledge of local geology and experience. The accuracy of the advice provided by PTG in this report may be affected
by undetected variations in ground conditions across the site between and beyond the sampling and/or testing
locations. For this reason our reports include an interpretation of conditions between the test points. There are
unknowns or variations in ground conditions between test locations that cannot be inferred or predicted. Such
variations may occur after PTG's field testing has been completed. The precision and reliability of interpretive
assessment between discrete points is dependent on the uniformity of the subsurface strata, as well as the frequency,
detail, and method of sampling or testing.
Geotechnical information represents an opinion and is based extensively on judgment of both data and interpretive
assessments or observation. This report and its associated documentation are provided explicitly based on PTG’s
opinion of the site at the time of inspection, and cannot be extended beyond this. Any recommendations or design
suggestions will need to be verified on site during project implementation or construction. Inspection and verification
on site may be conducted by a suitably qualified geotechnical consultant or engineer, and where subsurface conditions
or interpretations differ from those provided in this document or otherwise anticipated, PTG must be notified and be
provided with an opportunity to review the recommendations
The report has been prepared by qualified personnel, and is based on the information obtained from field and
laboratory testing, and has been undertaken to current engineering standards of interpretation and analysis. The
information and interpretation may not be relevant if the development proposal is changed. If this happens then PTG
Engineering will be pleased to review the report and the sufficiency of the investigation work.
Every care is taken with the report as it relates to interpretation of subsurface conditions, and the discussion and
recommendations or suggestions relating to the geotechnical aspects of the scope of works. However, PTG
Engineering cannot always anticipate or assume responsibility for:
» Unexpected variations in ground conditions.
» Changes in policy or interpretations of policy by statutory authorities.
» The actions of contractors responding to commercial pressures.
14
Page 15
PTG/04982 – 0001 – Rev0 – Rev0
The contents of this report do not constitute formal design components, as required by Health and Safety Legislation
and Regulations, to be included in a Safety Report specifying the hazards likely to be encountered during construction
and the controls required to mitigate risk. This design process requires risk assessment to be undertaken, with such
assessment being dependent upon factors relating to the likelihood of occurrence and consequences of damage to
property and to life. This, in turn, requires project data and analysis presently beyond the knowledge and project role
respectively of PTG.
This report must be read in conjunction with all of the attached documents and should be kept in its entirety without
separation of individual pages or sections. PTG cannot be held responsible for interpretations or conclusions made by
others unless they are supported by an expressed statement, interpretation, outcome, or conclusion stated in this
report.
15
Page 16
01 Appendix 1 Test Location Plan & Borehole Logs [OCR of page images] Appendix 1 Test Location Plan & Borehole Logs
Page 17
1 2 3 4 5 6 7 8 9 10
LEGEND:
A PTG BOREHOLE - 21.07.26 A
(POSITION APPROXIMATE)
BH01
A A'
A'
CROSS SECTION
B B
TOPOGRAPHIC CONTOURS
MAJOR INTERVAL = 5.0 m
SUBJECT SITE CADASTRAL
BOUNDARIES
C
C
OTHER PROPERTIES BH03
CADASTRAL BOUNDARIES
D D
NOTES:
1. CADASTRAL BOUNDARIES FROM QGLOBE
2. TOPOGRAPHIC CONTOURS EXTRACTED FROM DIGITAL
ELEVATION MODEL DATA OBTAINED FROM ELVIS
3. BOREHOLE LOCATIONS DETERMINED FROM HAND HELD GPS
4. UNDERLAY DRAWING SHOWING LAYOUT OF PROPOSED
DEVELOPMENT ADAPTED FROM DRAWING SET PREPARED BY
BAX ENGINEERING PTY LTD, TITLED "87 HAYWARD RD, LAKE E
E
MACDONALD QLD 4563", PROJECT NO. 146-019, REVISION BH02
DATE 09.07.26
F F
A
G G
BH01
H H
I I
J J
REV DATE DESCRIPTION DRAWN CHK COPYRIGHT Client North Project Drawing Title
0 10.08.26 REPORT ISSUE PH JT N LAKE MACDONALD CABINS TEST LOCATION PLAN
This document remains the property of PTG
CONSULTING and such may not be used, copied
SCG CONSULTING ENGINEERS
of reproduced, wholly or in part, without the express
permission of PTG CONSULTING.
Do not scale this drawing.
Address Address Drawn Approved Scale @ A3 Drawing Status
Figured dimension take precedence over scale. a: Level 3, 159 Coronation Drive (CNR Cribb St), Milton, QLD, 4064
p: (07) 3444 6666 87 HAYWARD ROAD PH JT 1:500 REPORT ISSUE
verify all dimensions on site. 1/11 PROJECT AVENUE e: [email protected]
NOOSAVILLE QLD 4566 w: https://www.ptgconsulting.com.au/
LAKE MACDONALD Designed Date Project No. Dwg No. Revision
PH 10.08.26 PTG/04982 0001 0
1 2 3 4 5 6 7 8 9 10
0 10 20 30 40 50 80 100
Page 18
1 2 3 4 5 6 7 8 9 10
LEGEND:
A A
BH7
PROPOSED GROUND
LEVEL
EXISTING GROUND
DRILLED BOREHOLE LEVEL B
B
? INFERRED STRATA
CONTACT BOUNDARY
C
C
EOB x.x m
D NOTES: D
1. EXISTING GROUND SURFACE ADAPTED FROM CONTOURS
DERIVED FROM DIGITIAL ELEVATION MODEL
2. PROPOSED GROUND PROFILE IS ASSUMED ONLY, BASED ON
INTERPRETATION OF GROUND SURFACE FROM DRAWING
PREPARED BY JFP URBAN CONSULTANTS, TITLED
PROPOSED DEVELOPMENT AT 260 RIDLEY ROAD, BRIDGEMAN
DOWNS, REF. NO. B4879EA1_DA2_2. DRAWING NO. EW01,
BH2
ISSUE A. PROVIDED BY B&L CIVIL PTY LTD
E
? E
?
? BH3
?
?
? STIFF - V
ERY STI
FF
? SILTY C
LA Y
HARD SILTY CLAY ?
? PROPOSED FILL
F ? F
?
?
?
EOB 6.0 m ?
?
HARD SILTY CLAY ? ? ? ?
EOB 6.0 m
G G
H H
I I
J J
REV DATE DESCRIPTION DRAWN CHK COPYRIGHT Client North Project Drawing Title
0 10.06.26 REPORT ISSUE PH JT N LAKE MACDONALD CABINS CROSS SECTION A - A'
This document remains the property of PTG
CONSULTING and such may not be used, copied
SCG CONSULTING ENGINEERS
of reproduced, wholly or in part, without the express
permission of PTG CONSULTING.
Do not scale this drawing.
Address Address Drawn Approved Scale @ A3 Drawing Status
Figured dimension take precedence over scale. a: Level 3, 159 Coronation Drive (CNR Cribb St), Milton, QLD, 4064
p: (07) 3444 6666 87 HAYWARD ROAD PH JT 1:250 REPORT ISSUE
verify all dimensions on site. 1/11 PROJECT AVENUE e: [email protected]
NOOSAVILLE QLD 4566 w: https://www.ptgconsulting.com.au/
LAKE MACDONALD Designed Date Project No. Dwg No. Revision
PH 10.08.26 PTG/04982 0002 0
1 2 3 4 5 6 7 8 9 10
0 10 20 30 40 50 80 100
Page 19
BOREHOLE BH01
CLIENT: SCG Consulting Pty Ltd DATE: 21/07/2026
PROJECT: Geotechnical Investigation EASTING: 494212 m
LOCATION: 87 Hayward Rd, Lake Macdonald, QLD, 4563 NORTHING: 7079583 m
PROJECT NUMBER: PTG/04982 SURFACE ELEV:
DRILLER: PTG Consulting Pty Ltd RIG: GT-10 LOGGED: JN CHECKED: PH
Sampling & Testing
Drilling Method
Layer Depths
Graphic Log
Strength Dynamic
Material Description (Consistency, Results & Penetrometer Test
Type (blows per 100 mm)
Comments
Water
Relative Density,
RL Depth Rock Strength)
(m) (m) 5 10 15 20
0 CI Silty CLAY, light pale brown with orange, medium plasticity, firm to 1
stiff, moist 2
2
0.3 red with orange brown 4
4
4
Firm to Stiff 5
5
4
1 3
4
6
6
1.3 pale red with pale grey, hard 11
16
12
16
17
18
2 20
3
Hard
4
PTG - BOREHOLE REPORT (NORMAL) PTG_04982 BH LOGS.GPJ DRAFT.GDT 23/8/26
5
6
Bore terminated at 6 m.
Target depth achieved.
Remarks:
Page 20
BOREHOLE BH02
CLIENT: SCG Consulting Pty Ltd DATE: 21/07/2026
PROJECT: Geotechnical Investigation EASTING: 494297 m
LOCATION: 87 Hayward Rd, Lake Macdonald, QLD, 4563 NORTHING: 7079612 m
PROJECT NUMBER: PTG/04982 SURFACE ELEV:
DRILLER: PTG Consulting Pty Ltd RIG: GT-10 LOGGED: JN CHECKED: PH
Sampling & Testing
Drilling Method
Layer Depths
Graphic Log
Strength Dynamic
Material Description (Consistency, Results & Penetrometer Test
Type (blows per 100 mm)
Comments
Water
Relative Density,
RL Depth Rock Strength)
(m) (m) 5 10 15 20
0 CI Silty CLAY, orange brown, medium plasticity, stiff to very stiff, moist 2
4
5
0.3 pale orange with grey, high plasticity 5
5
6
6
Stiff to Very Stiff 7
7
1 8
9
8
5
6
9
1.5 medium plasticity, hard, moist 20
2
3
3 pale red with pale grey, medium to high plasticity
Hard
4
PTG - BOREHOLE REPORT (NORMAL) PTG_04982 BH LOGS.GPJ DRAFT.GDT 23/8/26
4.5 pale orange with pale grey
5
6
Bore terminated at 6 m.
Target depth achieved.
Remarks:
Page 21
BOREHOLE BH03
CLIENT: SCG Consulting Pty Ltd DATE: 21/07/2026
PROJECT: Geotechnical Investigation EASTING: 494312 m
LOCATION: 87 Hayward Rd, Lake Macdonald, QLD, 4563 NORTHING: 7079632 m
PROJECT NUMBER: PTG/04982 SURFACE ELEV:
DRILLER: PTG Consulting Pty Ltd RIG: GT-10 LOGGED: JN CHECKED: PH
Sampling & Testing
Drilling Method
Layer Depths
Graphic Log
Strength Dynamic
Material Description (Consistency, Results & Penetrometer Test
Type (blows per 100 mm)
Comments
Water
Relative Density,
RL Depth Rock Strength)
(m) (m) 5 10 15 20
0 CI Silty CLAY, pale brown orange with orange, medium plasticity, very 6
stiff to hard, moist 8
Very Stiff to Hard
11
0.3 stiff to very stiff 6
0.4 red brown with pale grey, medium to high plasticity 4
6
Stiff to Very Stiff 7
8
9
1 9
1 hard 11
10
12
14
11
15
13
13
10
2 14
20
3
3 orange with pale grey
Hard
4
PTG - BOREHOLE REPORT (NORMAL) PTG_04982 BH LOGS.GPJ DRAFT.GDT 23/8/26
5
6
Bore terminated at 6 m.
Target depth achieved.
Remarks:
Page 22
02 Appendix 2 Laboratory Test Results [OCR of page images] Appendix 2 Laboratory Test Results
Page 23
Protest CMT
ABN: 26602913673
www.protestcmt.com.au
Protest CMT
California Bearing Ratio Report
Client : Internal Project Report Number : SR/PTG/04982 - 1/1
Client Address : Internal Project Report Date : 10/08/2026
Project Name : 87 Hayward Drive Lake MacDonald Test Request : -
Project Number : PTG/04982
Page 1 of 1
Location : Not Provided
Test Methods : AS1289.6.1.1, AS1289.5.1.1, AS1289.2.1.1
Material Description : Clay
Sample Number : S/371555 Sampling Location : Client Selected
Date(s) Tested : 29/07/2026 - 10/08/2026 Sampling Method : As Received
Material Source : Insitu Time : 00:00
For Use As : Proposed subgrade Location 1 : BH03
Lot Number : - Location 2 : 0.5 - 1.5 m
Location 3 : -
Specification (CBR Value) : -
Location 4 : -
MDD (t/m³) : 1.55 Nominated % of MDD : 100.0% Target Dry Density (t/m³) : 1.55 Achieved % of MDD : 100.0%
OMC (%) : 25.9 Nominated % of OMC : 100.0% Target Moisture Content (%) : 25.9 Achieved % of OMC : 100.5%
Compactive Effort : Standard
Dry Density Before Soak (t/m³) : 1.54
CBR 1 Point Graph
4000
Dry Density After Soak (t/m³) : 1.54
Field Moisture Content (%) : 26.0%
3500
Compaction Moisture Content (%) : 26.0%
After Penetration - Top Moisture (%) : 27.1% 3000
After Penetration - Total Moisture (%) : 26.7%
Period of Soaking (Days) : 4 2500
Mass of Surcharge (kg) : 4.5
Load (N)
Oversize (%) : 0.0% 2000
Oversize Included : Excluded
1500
Method of Determining Plasticity : Tactile/Visual Assessment
CBR Sample Curing Time : 71 Hours
1000
- -
- -
500
Swell (%) : 0.0%
0
0 2.5 5 7.5 10 12.5 15
CBR Value at 5mm : 4.5% Penetration (mm)
Pre-treatment (CAn) : -
Pre-treatment (Wn) : -
Mass Retained (R) : -
-
Remarks :
APPROVED SIGNATORY
Note: The results contained in this report relate only to the item/s that were tested/sampled
Accredited for Compliance with ISO/ IEC 17025 - Testing
Protest CMT (Sunshine Coast) Accreditation Number - 19667
Base Laboratory Site Number - 24490 - Sunshine Coast
Base Laboratory Address - Unit 2/9-13 Matheson Street, Baringa, 4551, QLD David Kent - Signatory
Document Number : RF03 Date : 12/01/2026
Page 24
Protest CMT
ABN: 26602913673
www.protestcmt.com.au
Protest CMT
Atterberg Limits Report
Client : Internal Project Report Number : SR/PTG/04982 - 2/1
Client Address : Internal Project Report Date : 10/08/2026
Project Name : 87 Hayward Drive Lake MacDonald Test Request : -
Project Number : PTG/04982
Page 1 of 2
Location : Not Provided
Test Methods : AS1289.3.9.2, AS1289.3.2.1, AS1289.3.4.1, AS1289.3.3.2, AS1289.2.1.1
Material Description : Refer to Logs
Sample Number : S/371550 Sampling Location : Client Selected
29/07/2026 -
Date(s) Tested : Sampling Method : As Received
10/08/2026
Material Source : Insitu Time : 00:00
For use as : Proposed subgrade Location 1 : BH02
Lot Number : - Location 2 : 0.3 m - 1.6 m
Location 3 : -
ATT Specification Number : N/A Location 4 : -
History of Sample : Oven Dried
Method of Preparation : Dry Sieved
Linear Shrinkage & Defects : No Cracking or Curling Occurred
Mould Length (mm) : 127
Atterberg Limits Test Results Liquid Limit (%) : Plastic Limit (%) : Plasticity Index (%) : Linear Shrinkage (%) :
Results : 69 30 39 12.0
Specifications :
Remarks :
Note: The results contained in this report relate only to the item/s that were tested/sampled APPROVED SIGNATORY
Accredited for Compliance with ISO/ IEC 17025 - Testing
Protest CMT (Sunshine Coast) Accreditation Number - 19667
Base Laboratory Site Number - 24490 - Sunshine Coast
Base Laboratory Address - Unit 2/9-13 Matheson Street, Baringa, 4551, QLD David Kent - Signatory
Document Number : RF05 Date : 29/07/2026
Page 25
Protest CMT
ABN: 26602913673
www.protestcmt.com.au
Protest CMT
Atterberg Limits Report
Client : Internal Project Report Number : SR/PTG/04982 - 2/1
Client Address : Internal Project Report Date : 10/08/2026
Project Name : 87 Hayward Drive Lake MacDonald Test Request : -
Project Number : PTG/04982
Page 2 of 2
Location : Not Provided
Test Methods : AS1289.3.9.2, AS1289.3.2.1, AS1289.3.4.1, AS1289.3.3.2, AS1289.2.1.1
Material Description : Refer to Logs
Sample Number : S/371553 Sampling Location : Client Selected
29/07/2026 -
Date(s) Tested : Sampling Method : As Received
10/08/2026
Material Source : Insitu Time : 00:00
For use as : Proposed subgrade Location 1 : BH03
Lot Number : - Location 2 : 0.4 m - 1.0 m
Location 3 : -
ATT Specification Number : N/A Location 4 : -
History of Sample : Oven Dried
Method of Preparation : Dry Sieved
Linear Shrinkage & Defects : No Cracking or Curling Occurred
Mould Length (mm) : 124
Atterberg Limits Test Results Liquid Limit (%) : Plastic Limit (%) : Plasticity Index (%) : Linear Shrinkage (%) :
Results : 45 21 24 9.0
Specifications :
Remarks :
Note: The results contained in this report relate only to the item/s that were tested/sampled APPROVED SIGNATORY
Accredited for Compliance with ISO/ IEC 17025 - Testing
Protest CMT (Sunshine Coast) Accreditation Number - 19667
Base Laboratory Site Number - 24490 - Sunshine Coast
Base Laboratory Address - Unit 2/9-13 Matheson Street, Baringa, 4551, QLD David Kent - Signatory
Document Number : RF05 Date : 29/07/2026
Page 26
Protest CMT
ABN: 26602913673
www.protestcmt.com.au
Emerson Class Report
Client : Internal Project Report Number : SR/PTG/04982 - 3/1
Client Address : Internal Project Report Date : 24/08/2026
Project Name : 87 Hayward Drive Lake MacDonald Test Request : -
Project Number : PTG/04982
Page 1 of 1
Location : Not Provided
Test Methods : AS1289.3.8.1
Sample Number : S/371548 S/371551 S/371554
29/07/2026 - 29/07/2026 - 29/07/2026 -
Date/s Tested :
24/08/2026 24/08/2026 24/08/2026
Material Source : Insitu Insitu Insitu
For Use As : Proposed subgrade Proposed subgrade Proposed subgrade
Sampling Location : Client Selected Client Selected Client Selected
Sampling Method : As Received As Received As Received
Time : 00:00 00:00 00:00
Lot Number : - - -
Location 1 : BH01 BH02 BH03
Location 2 : 0.3 m - 1.3 m 3.0 m - 4.5 m 1.0 m - 1.5 m
Location 3 : - - -
Location 4 : - - -
Water Type : Distilled Distilled Distilled
Soil Description : Refer to Logs Refer to Logs Refer to Logs
Emerson Specification Number : N/A N/A N/A
Specification Limits : - - -
Emerson Class Number : 6 6 5
Remarks :
APPROVED SIGNATORY
Note: The results contained in this report relate only to the item/s that were tested/sampled
Accredited for Compliance with ISO/ IEC 17025 - Testing
Protest CMT (Sunshine Coast) Accreditation Number - 19667
Base Laboratory Site Number - 24490 - Sunshine Coast
Base Laboratory Address - Unit 2/9-13 Matheson Street, Baringa, 4551, QLD David Kent - Signatory
Document Number : RF6 Date : 24/03/2026
Page 27
Protest CMT
ABN: 26602913673
www.protestcmt.com.au
Shrink/Swell Index (Iss)
Client : Internal Project Report Number : SR/PTG/04982 - 4/1
Client Address : Internal Project Report Date : 24/08/2026
Project Name : 87 Hayward Drive Lake MacDonald Test Request : -
Project Number : PTG/04982
Page 1 of 1
Location : Not Provided
Test Methods : AS1289.7.1.1, AS1289.2.1.1
Material Description : Refer to Logs
Sample Number : S/371549 Time : 00:00
Date Tested : 29/07/2026 Location 1 : BH01
Material Source : Insitu Location 2 : 0.6 m - 1.2 m
For Use As : Proposed subgrade Location 3 : -
Lot Number : - Location 4 : -
Sampling Location : Client Selected
Sampling Method : As Received
Shrinkage Test Results Swell Test Results
Significant Inert Inclusions
0% Initial Moisture Content : 21.4%
:
Extent of Cracking : 0% Final Moisture Content : 33.2%
Extent of Soil Crumbling : 0%
Moisture Content of Shrinkage Sample
26.2%
:
Shrink-Swell Index (Iss %) : 1.9
Swell Pressure (Kpa) :
Unit Weight (t/m³) :
-
Remarks :
Note: The results contained in this report relate only to the item/s that were tested/sampled APPROVED SIGNATORY
Accredited for Compliance with ISO/ IEC 17025 - Testing
Protest CMT (Sunshine Coast) Accreditation Number - 19667
Base Laboratory Site Number - 24490 - Sunshine Coast
Base Laboratory Address - Unit 2/9-13 Matheson Street, Baringa, 4551, QLD David Kent - Signatory
Document Number : RF36 Date : 12/12/2025
Page 28
Protest CMT
ABN: 26602913673
www.protestcmt.com.au
Shrink/Swell Index (Iss)
Client : Internal Project Report Number : SR/PTG/04982 - 4/1
Client Address : Internal Project Report Date : 24/08/2026
Project Name : 87 Hayward Drive Lake MacDonald Test Request : -
Project Number : PTG/04982
Page 1 of 1
Location : Not Provided
Test Methods : AS1289.7.1.1, AS1289.2.1.1
Material Description : Refer to Logs
Sample Number : S/371552 Time : 00:00
Date Tested : 29/07/2026 Location 1 : BH02
Material Source : Insitu Location 2 : 0.5 m - 1.2 m
For Use As : Proposed subgrade Location 3 : -
Lot Number : - Location 4 : -
Sampling Location : Client Selected
Sampling Method : As Received
Shrinkage Test Results Swell Test Results
Significant Inert Inclusions
0% Initial Moisture Content : 24.6%
:
Extent of Cracking : 0% Final Moisture Content : 27.0%
Extent of Soil Crumbling : 0%
Moisture Content of Shrinkage Sample
23.7%
:
Shrink-Swell Index (Iss %) : 1.1
Swell Pressure (Kpa) :
Unit Weight (t/m³) :
-
Remarks :
Note: The results contained in this report relate only to the item/s that were tested/sampled APPROVED SIGNATORY
Accredited for Compliance with ISO/ IEC 17025 - Testing
Protest CMT (Sunshine Coast) Accreditation Number - 19667
Base Laboratory Site Number - 24490 - Sunshine Coast
Base Laboratory Address - Unit 2/9-13 Matheson Street, Baringa, 4551, QLD David Kent - Signatory
Document Number : RF36 Date : 12/12/2025
Page 29
03 Appendix 3 Slope Stability Analysis Results [OCR of page images] Appendix 3 Slope Stability Analysis NSH ON LS
Page 30
225
2.973
200
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
Divisions along slope:20
Circles per division:10
Number of iterations:10
175
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Every available surface
150
2.973
125
W
W
100
Unit
Strength Cohesion Phi Water Hu
Material Name Color Weight Hu
Type (kPa) (°) Surface Type
(kN/m3)
1D - St - Vst Silty Mohr- Water
18 5 23 Custom 1
CLAY (Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
(Natural) Coulomb Table
-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Existing E1 - Assumed GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 31
225
2.946
200
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
Minimum Elevation:Not Defined
175
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
Every available surface
2.946
150
125
W
W
100
Unit
Strength Cohesion Phi Water Hu
Material Name Color Weight Hu
Type (kPa) (°) Surface Type
(kN/m3)
1D - St - Vst Silty Mohr- Water
18 5 23 Custom 1
CLAY (Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
(Natural) Coulomb Table
-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Existing E2 - Assumed GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 32
225
2.299
200
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
Divisions along slope:20
Circles per division:10
Number of iterations:10
175
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Every available surface
150
2.299
W
125
W
100
Unit
Strength Cohesion Phi Water Hu
Material Name Color Weight Hu
Type (kPa) (°) Surface Type
(kN/m3)
1D - St - Vst Silty Mohr- Water
18 5 23 Custom 1
CLAY (Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
(Natural) Coulomb Table
-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Existing E3 - Raised GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 33
225
2.270
200
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
Minimum Elevation:Not Defined
175
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
Every available surface
2.270
150
W
125
W
100
Unit
Strength Cohesion Phi Water Hu
Material Name Color Weight Hu
Type (kPa) (°) Surface Type
(kN/m3)
1D - St - Vst Silty Mohr- Water
18 5 23 Custom 1
CLAY (Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
(Natural) Coulomb Table
-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Existing E4 - Raised GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 34
150
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
Divisions along slope:20
Circles per division:10
140
Number of iterations:10
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
130
Minimum Weight:Not Defined
Every available surface
1.842
1.842
120
110
W
100
Unit Weight Strength Cohesion Phi Water Hu
Material Name Color Hu
(kN/m3) Type (kPa) (°) Surface Type
1D - St - Vst Silty CLAY Mohr- Water
18 5 23 Custom 1
(Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
90
(Natural) Coulomb Table
3D - Vst - H Silty CLAY Mohr- Water
18 5 20 Custom 1
(Fill) Coulomb Table
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed P1 - Assumed GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 35
150
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
140
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
130
Every available surface
1.822
1.822
120
110
W
100
Unit Weight Strength Cohesion Phi Water Hu
Material Name Color Hu
(kN/m3) Type (kPa) (°) Surface Type
1D - St - Vst Silty CLAY Mohr- Water
18 5 23 Custom 1
(Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
90
(Natural) Coulomb Table
3D - Vst - H Silty CLAY Mohr- Water
18 5 20 Custom 1
(Fill) Coulomb Table
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed P2 - Assumed GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 36
150
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
Divisions along slope:20
Circles per division:10
140
Number of iterations:10
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
130
Minimum Weight:Not Defined
Every available surface
1.772
1.772
120
110
W
100
Unit Weight Strength Cohesion Phi Water Hu
Material Name Color Hu
(kN/m3) Type (kPa) (°) Surface Type
1D - St - Vst Silty CLAY Mohr- Water
18 5 23 Custom 1
(Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
90
(Natural) Coulomb Table
3D - Vst - H Silty CLAY Mohr- Water
18 5 20 Custom 1
(Fill) Coulomb Table
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed P3 - Raised GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 37
150
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
140
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
130
1.772 Every available surface
1.772
120
110
W
100
Unit Weight Strength Cohesion Phi Water Hu
Material Name Color Hu
(kN/m3) Type (kPa) (°) Surface Type
1D - St - Vst Silty CLAY Mohr- Water
18 5 23 Custom 1
(Natural) Coulomb Table
2D - H Silty CLAY Mohr- Water
18 6 25 Custom 1
90
(Natural) Coulomb Table
3D - Vst - H Silty CLAY Mohr- Water
18 5 20 Custom 1
(Fill) Coulomb Table
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed P4 - Raised GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 38
150
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
3.134 Divisions along slope:20
Circles per division:10
140
Number of iterations:10
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
130
Minimum Weight:Not Defined
Every available surface
3.134
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Filled P5 - Assumed GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 39
150
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
140
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
130
2.670 Every available surface
2.670
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Filled P6 - Assumed GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 40
150
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
3.133 Divisions along slope:20
Circles per division:10
140
Number of iterations:10
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
130
Minimum Weight:Not Defined
Every available surface
3.133
120
110
W
100
Unit Weight (kN/ Strength Cohesion Cohesion Water Ru
Material Name Color
m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY (Natural) 18 Undrained 60 Constant None 0
90
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Filled P7 - Raised GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 41
150
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
140
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
130
2.669 Every available surface
2.669
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Filled P8 - Raised GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 42
150
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
Divisions along slope:20
Circles per division:10
140
Number of iterations:10
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
130
3.315 Minimum Weight:Not Defined
Every available surface
3.315
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Pre-Filled P9 - Assumed GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 43
150
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
140
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
130
Every available surface
2.928
2.928
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Pre-Filled P10 - Assumed GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 44
150
Results
Spencer
Surface Type: Circular
Search Method:Auto Refine Search
Divisions along slope:20
Circles per division:10
140
Number of iterations:10
Divisions to use in next iteration:50%
Composite Surfaces:Disabled
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
130
3.315 Minimum Weight:Not Defined
Every available surface
3.315
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Pre-Filled P11 - Raised GW - C
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 45
150
Results
Spencer
Search Method:Cuckoo Search
Initial # of Surface Vertices:8
Maximum Iterations:500
Number of Nests:50
140
Minimum Elevation:Not Defined
Minimum Depth:Not Defined
Minimum Area:Not Defined
Minimum Weight:Not Defined
Convex Surfaces Only:Enabled
Optimize Surfaces:Enabled
130
Every available surface
2.930
2.930
120
110
W
100
Unit Weight Strength Cohesion Cohesion Water Ru
Material Name Color
(kN/m3) Type (kPa) Type Surface Value
1U - St - Vst Silty CLAY
18 Undrained 20 Constant None 0
(Natural)
2U - H Silty CLAY
18 Undrained 60 Constant None 0
90
(Natural)
3U - Vst - H Silty CLAY
18 Undrained 50 Constant None 0
(Fill)
0 10 20 30 40 50 60 70 80 90 100 110 120
Project
PTG-04982 - Lake MacDonald Cabins - Hayward Rd
Group Scenario
Proposed - Undrained - Pre-Filled P12 - Raised GW - NC
Drawn By Company
PH PTG Consulting
Date File Name
SLIDEINTERPRET 9.043
10/08/2026 PTG-04982 - Section A - Run1.slmd
Page 46
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