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Slope Stability Analysis
[email protected]
arcosgroup.com.au
ABN 51 640 311 841
Attention: c/- Global Testing 10 Jul 2025
By Email ARCOS PROJECT:2500199.05
Report 01 Revision Rev A
Report on Slope Stability Analysis
Proposed Residential Development
15 & 17 Myall Street, Cooroy
Arcos Unit Group Pty Ltd (Arcos Group) has undertaken a geotechnical assessment for the above project and client.
SUMMARY OF ASSESSMENT
Results of Australian Geomechanic Society Landslide Risk Assessment
Low
Note: The above is a summary of the detailed investigation results discussed within this report. The entire report must be read,
understood and kept in entirety.
Senior Geotechnical Engineer
Andre Dos Santos B.Eng (Civ), MIEAust, RPEQ,
CPEng, NER
[email protected]
For and On Behalf of Arcos Group
Sunshine Coast | Brisbane | Gold Coast
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1 INTRODUCTION
Arcos Unit Group Pty Ltd (Arcos Group) was commissioned to undertake a slope stability analysis for the project at
the location described on the title page of this report.
This report outlines the results of the investigation and laboratory testing by Global Testing, analysis, and interpretive
reporting on the following items:
Review of the existing slope stability hazards, their attributed risks and impacts of the proposed development in
alignment with the practices set out within the Australian Geomechanics Society guidelines; and,
Provide recommendations from a geotechnical context that will avoid or reduce any potential instability.
This report must be kept in entirety. The use of this document is exclusively undertaken in accordance with our terms
and conditions.
2 REGIONAL GEOLOGY
The site is in an area underlain by Eocene aged Pomona beds, which typically comprises “shale, sandstone,
conglomerate, basalt”.
3 EXISTING STABILITY RISK
Local authorities prepare mapping tools to aid in assessing potential slope stability requirements. The mapping tools
are a “high level” approach where the site specific investigations are specific to a particular site/allotment. It is
important to note that where a site specific investigation and slope stability assessment are undertaken, they take
precedence.
Reference to the available overlays for the area show that a portion of the site has been initially mapped as
“Moderate” in terms of landslide hazard.
4 GEOTECHNICAL INVESTIGATION
A geotechnical investigation was undertaken for the development by Global Testing in May 2025. The investigation
included the drilling and sampling of six bores to a maximum depth of 4.5 m. Dynamic cone penetrometer (DCP)
testing was undertaken in each bore to provide information on the strength consistency of the subsurface. The
detailed bore log sheets are attached; however, in summary, the subsurface conditions encountered in the bores
generally comprised surficial clayey sand underlain by sandy clay, inferred to be residual soil. The strength
consistency of the sandy clay is typically firm to stiff initially, grading very stiff to hard with depth. No groundwater
seepage was observed in the bores; however, it should be noted that groundwater is transient and can fluctuate with
seasonal changes and human influences (such as broken infrastructure).
5 WALKOVER ASSESSMENT
Geotechnical comments are based on the factual findings of the investigation, best practice, local experience,
published correlations; however, are fundamentally founded in opinion and this should be considered.
The site is located on the eastern flank of the Maple Street ridge. Topographically, the surface elevation at the site
falls in a easterly direction down to Myall Street. Slopes angles range between 5° and 10°. There are no obvious
signs of recent or previous instability at the site (such as disturbed ground, tension cracks or hummocks). A variety
of vegetation ranging from small shrubs to mature trees were observed. The mature trees were all observed to be
typically vertical with no misshapen or curved trunks. Misshapen or curved trunks are usually good indicators for
previous slope instability.
Sunshine Coast | Brisbane | Gold Coast
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Sunshine Coast | Brisbane | Gold Coast
6 AGS ASSESSMENT
Landslides are caused where a soil or rock mass has a decrease in strength, usually attributed to groundwater,
resulting in the material not being able to maintain its own self-weight resulting in a slope failure.
The Australian Geomechanics Society (AGS) developed a set of tools and procedures for assessing the stability of
a slope. The tools and procedures presented with the AGS documentation form the basis of the assessment
undertaken herein and their documentation is attached for reference.
The guidelines also identify that the regulator typically sets the standard for levels of tolerable risk. AGS defines
tolerable risk as “risks within a range that society can live with so as to secure certain benefits. It is a range of risk
regarded as non-negligible and needing to be kept under review and reduced further if practicable”.
The guides suggest that areas of moderate or greater risk should not be developed unless a rigorous remediation
plan be implemented to reduce the area to a level of Acceptable Risk. AGS defines acceptable risk as “risk which
everyone affected is prepared to accept. Action to further reduce such risk is usually not required unless reasonably
practicable measures are available at low cost in terms of money, time and effort.”.
AGS suggest that regulators generally accept risk levels of “low” or lower as a level of acceptable risk.
AGS prepared a semi-quantitative assessment tool for determining the level of risk for a site. The tool separates the
potential hazards for a site, from a stability context, and rates them with a level of risk frequency. The multiplication
of these individual risk frequency summates as the risk frequency rating which is then measured against the levels
of risk nominated by AGS.
The results of this analysis are shown in Table 1.
TABLE 1: AGS ASSESSMENT
Hazard Likelihood Consequence Risk Level
Global Failure Barely Credible Major Very Low
Creep in Shallow Soils Unlikely Minor Low
Rotational or translational slide down Unlikely Minor Low
the slope
Failure of engineered retaining walls Rare Medium Low
Based on the results of the AGS assessment, the perceived risk based on the conditions encountered and information
available at the time of the assessment is “Low”.
7 HILLSIDE CONSTRUCTION
The following works should be implemented in addition to other items highlighted within this document. These points
are considered to be typical good hillside construction practice as explained in attached documentation:
Footings should be founded into stiff (or stronger) natural clays. Alternatively, if a perimeter retaining structure
has been designed and incorporated that retains a building platform and accommodates the appropriate shear
resistance to resist any mobilising forces associated with sliding masses, footings could found in controlled fill
with review by this office to confirm assumptions.
Fill should be step keyed into the existing slope. The fill should be formed at no steeper than 3H:1V, unless
retained by an engineered retention system. All fill should be placed in accordance with AS3798.
Where slopes are not supported by an engineer designed support system, natural slopes or cuts within or near
movement sensitive areas should be no steeper than 2.5H:1V.
All stormwater and surface water is to be discharged by an approved stormwater drainage system. The use of
subsurface drainage systems are not suitable unless greater than 50 m downslope from the envelope at this site.
Sunshine Coast | Brisbane | Gold Coast
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Sunshine Coast | Brisbane | Gold Coast
The design of retaining walls should be undertaken by a suitably qualified RPEQ engineer. Retaining walls must
be designed to achieve a minimum safety factor of 1.5 against global instability.
Avoid leakage from underground services and drains. Any leaking services or blocked drains should be remedied
promptly.
Erosion protection of cut and fill batters will be required. Batters should incorporate crest and toe drainage. Batters
should be vegetated appropriately to minimise erosion.
Overland flow paths will need to be carefully directed to approved outlets to minimise erosion possibility.
8 GEOTECHNICAL RECOMMENDATIONS
The following sections details specific geotechnical constraints or recommendations in addition to general hillside
construction notes.
8.1 FOOTINGS
In accordance with industry standards, a geotechnical engineer from Arcos should undertake the testing within the
footings to confirm that the encountered material is in alignment with the adopted parameters and assumptions
provided within this report. Where this does not occur, Arcos cannot be held liable for any of the information presented
within this report.
All footings will need to be designed to accommodate potential ground surface movement, settlement values and
any additional settlement values associated with the placement of new fill.
Settlement for suitably sized and designed high level footings should be in the order of 1-2% of the width of the
footing.
If footings are located adjacent to an underground service or other obstruction that is not homogenous with the
founding strata, the footing should be extended a minimum 0.3 m below an imaginary line projected at a 45 degree
angle from the lowest point of the service/obstruction. This is depicted graphically for reference:
Where footings found into stiff (or stronger) clays, they may be dimensioned for a maximum allowable bearing
pressure of 100 kPa.
The ultimate geotechnical end bearing and shaft adhesion parameters are presented in Table 2 for deep level
footings where high level footings are not suitable. The values given will need to reduced by applying a suitable
geotechnical strength reduction factor (Φg) for limit state or divided by a suitable factor of safety for working stress
methods. The Φg should be selected by the designer.
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TABLE 2: DEEP LEVEL FOOTING – ULTIMATE GEOTECHNICAL PARAMETERS (LONG PILE)
Material Bored Bored Screw Screw
Fb (kPa) Fs (kPa) Fb (kPa) Fs (kPa)
Stiff (or stronger) clays 450 30 NR NR
Notes: Fb = Base Bearing (Ultimate); Fs = Shaft Adhesion (Ultimate)
The upper 1 m of soil profile should be ignored in shaft calculations for bored piles to allow for shrinkage cracks. The
values presented in Table 2 assume that the material equal to four pile diameters below the base of any footings is
as strong or stronger.
Settlement values are subjected to a variety of factors; however, a properly designed and constructed pile should
have a serviceability settlement between 1% and 2% of its’ diameter.
ATTACHMENTS
About Your Geotechnical Report
Interpretation of the Subsurface Sheets
Practice Note Guidelines
Client Supplied Information
Sunshine Coast | Brisbane | Gold Coast
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Sunshine Coast | Brisbane | Gold Coast
ABOUT YOUR GEOTECH REPORT
Reporting
These notes have been provided to clarify and The report has been prepared and reviewed by
enhance the reader’s understanding of the suitably qualified and experienced persons. The
terminology used throughout the report, and also to persons draw on previous experience, local
identify where limitations exist. All investigations are knowledge, published literature, and otherwise
undertaken based on budgetary constraints which standard engineering approaches and principals. The
impart a level of uncertainty as a result of limiting the context of which the report has been prepared for must
amount of investigation undertaken. be considered and if the context changes, due
consideration should be given to the possibility that the
report is no longer considered relevant and review by
Copyright Arcos Unit Group Pty Ltd must be undertaken.
This report remains the property of Arcos Unit Group Arcos Unit Group Pty Ltd undertakes quality
Pty Ltd at all times unless ownership is transferred in assurance checks in accordance with its’ quality
writing. It cannot be included in any documentation system requirements; however, restrictions on the
without the express written permission of Arcos Unit project outside of Arcos Unit Group Pty Ltd’s control
Group Pty Ltd can result in unanticipated variations, changes in
policy or interpretation of said policies by the relevant
authority, or the actions of contractors subject to
Subsurface Report Sheets (Bores etc) commercial pressure.
The provided subsurface sheets are inherently an
interpretation undertaken by a suitably qualified and
experienced person; however, the reliability of the
Site Variations
provided information will rely on the method of If site variations become evident at the time of
investigation. It is prudent to state that these sheets construction or after the release of a report, Arcos Unit
only represent a very small percentage of the Group Pty Ltd requests immediately notification. This
subsurface conditions across a particular project. notification is proposed in order to assist in
remediation prior to any permanent structures or
It reasons that given the relatively small representation
design procedures are undertaken.
of the subsurface conditions for a project, spacial
variability between testing locations must be taken into
consideration including the orientation of strata Collaboration
intersections.
Arcos Unit Group Pty Ltd strongly recommends open
The presence or lack of groundwater is usually stated and collaborative communication about the use and
on the subsurface sheets; however, it must be noted inherent interpretation of Arcos Unit Group Pty Ltd’s
that the measurements undertaken onsite are typically report. Please contact the author of the report to
very inaccurate and if the presence or lack of arrange for an obligation free discussion regarding the
groundwater will have any degree of affect on the potential benefits of having geotechnical consultants.
project, additional groundwater monitoring techniques
should be employed such as groundwater monitoring
wells.
Sunshine Coast | Brisbane | Gold Coast
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Sunshine Coast | Brisbane | Gold Coast
Interpretation of the Subsurface Sheets
The terminology included on Arcos Unit Group Pty the most important component. Typically, the strength
Ltd’s has been evolved from AS1726:2016. Typically of rock is based on laboratory testing, tactile
a soil’s strength, colour, plasticity, grain size, other assessment and other observations as relevant. The
inclusions, and moisture will be described. A rock’s industry standard method for assessing the strength of
strength, weathering, colour, grain, and other rock in the field is to use the point load strength index
inclusions are typically described. (AS4133.4.1). It is important to note that the point load
strength index does not take into consideration the
degree of fracturing of a rock mass which can both
Soil lower and increase the overall rock strength. The
Soil is typically described by the components that strength of rock is broken down as follows:
make it up by percentage or whichever has a Very Low Strength (VLS) < 2 MPa (UCS)
governing behaviour. The types and sizes reproduced Low Strength (LS) 2 to 6 MPa (UCS)
from AS1726 are: Medium Strength (MS) 6 to 20 MPa (UCS)
Boulder >200 mm High Strength (HS) 20 to 60 MPa (UCS)
Cobble 63 to 200 mm Very High Strength (VHS) 60 to 200 MPa (UCS)
Gravel 2.36 to 63 mm Extremely High Strength (EHS) > 200 MPa (UCS)
Sand 0.075 to 2.36 mm Very Low Strength (VLS) < 0.1 Is(50)
Silty 0.002 to 0.075 mm Low Strength (LS) 0.1 to 0.3 Is(50)
Clay < 0.002 mm Medium Strength (MS) 0.30 to 1.0 Is(50)
The strength of soil is usually assessed by suitably High Strength (HS) 1.0 to 3.0 Is(50)
experienced persons through the use of laboratory Very High Strength (VHS) 3.0 to 10.0 Is(50)
test results, published literature, field assessments or Extremely High Strength (EHS) > 10.0 Is(50)
a combination of the above. The strength of soil is The Is(50) values are based on a correlation between
characterised into either cohesive (clays and silts) or the unconfined compressive strength (UCS) of 20.
cohesionless (sands and gravels) as shown below: This value varies significantly and site specific testing
Cohessive Soil Strength Term must take precedence.
Very Soft < 12.5 kPa Rock weathering is broken down as follows:
Soft 12.5 to 25 kPa Extremely weathered (EW) Behaves as soil but rock structure
Firm 25 to 50 kPa evident
Stiff 50 to 100 kPa Highly weathered (HW) Colour and strength of original fresh rock
is not recognisable. Decomposition of rock evident
Very Stiff 100 to 200 kPa
Moderately weathered (MW) Defects are heavily stained with
Hard > 200 kPa
rock mass showing signs of discolouration
Cohesionless Soils Strength Term (uncorrected Qc) Slightly weathered (SW) Some staining but minimal to no
Very Loose <2 MPa change in strength
Loose 2 to 5 MPa Fresh stained (FS) Minor staining evident
Medium Dense 5 to 15 MPa Fresh rock (FR) No change
Dense 15 to 25 MPa Rock fracturing is broken down as follows and can only
Very Dense > 25 MPa be accurately described where undamaged
continuous sampling has been undertaken:
Fragmented (Fg) Defect spacings < 20 mm
Rock
Highly Fractured (HF) Defect spacings 20 to 50 mm
Rock is typically described by the components that Fractured (Fr) Defect spacings 50 to 200 mm
make it up by percentage or whichever has a Slightly Fractured (SF) Defect spacings 200 to 1000 mm
governing behaviour. The strength of rock is typically Unbroken (Ub) Defect spacings > 1000 mm
Sunshine Coast | Brisbane | Gold Coast
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Sunshine Coast | Brisbane | Gold Coast
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QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
JOB NUMBER 25-0664 SITE CLASSIFICATION REPORT
CLIENT MACKY GROUP
SITE LOCATION PROPOSED DWELLING
15 & 17 MYALL STREET, COOROY
REPORT DATE 26/05/2025
1. INTRODUCTION
The purpose of this report is to classify the subject allotment in accordance with Australian Standard
2870 - 2011 'Residential Slabs and Footings'. From this classification, a footing system can be recom-
mended for the structure so as to allow adequate performance of the footings under the soil conditions
determined at the site.
Trees: There are small (<5m), medium (5-10m), and large (>10m) trees at this site. Global Testing
recommends an experienced arborist be commissioned to quantify the existing size, location, pre-
dicted maximum height and type of these trees to aid in the design process. It is the responsibility of
the designing engineer to apply the principals of AS2870-2011 Appendix H 'Guide to Design of Foot-
ings for Trees'. The classification herein excludes the effect of trees on the site.
2. SITE DESCRIPTION
Type of Allotment Residential
Vegetation Grassed/Scattered Undergrowth
Slope 6% to 8% to East
Surface Water will Drain Towards East
Will Surface Water from adjoining No
allotments traverse this site?
Surrounding Allotments
Left Dwelling
Right Dwelling
Rear Dwelling
Depth to Weathered Rock BH1 (2.0m)
Depth to Water Table BH5 (4.0m)
3. SITE CLASSIFICATION AND TARGET STRATA
Based on the findings of the site investigation, the classification of the site is considered to conform to:
CLASS “M” – (Due to Fill, Trees, and Poor Bearing Capacity - See Target
Stratum)
NOTE: If not for the above reasons, the site would have Class H1 characteristics.
in accordance with Australian Standard 2870 - 2011, 'Residential Slabs and Footings, Construction'.
The target stratum for the foundation of the structure located at BH1 is the SANDY CLAY en-
countered at 400 mm below existing ground level.
The target stratum for the foundation of the structure located at BH2 is the SANDY CLAY en-
countered at 500 mm below existing ground level.
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The target stratum for the foundation of the structure located at BH3 is to be determined by the
designing engineer.
The target stratum for the foundation of the structure located at BH4 is the SANDY CLAY en-
countered at 400 mm below existing ground level.
The target stratum for the foundation of the structure located at BH5 is the SANDY CLAY en-
countered at 500 mm below existing ground level.
The target stratum for the foundation of the structure located at BH6 is the SANDY CLAY en-
countered at 400 mm below existing ground level.
It is the designing engineer’s responsibility to address the potential influence of any trees present
on or around the proposed building site.
If any fill is placed over the existing ground, the structure shall be piered through the fill into the
existing material. Further note that the placement of reactive material as fill, or cutting of the
site may change the site’s classification.
4. SOIL PROFILE
Refer to Soil Profile Report for borelog information.
Whilst every effort has been made to ensure that the borelogs carried out at the subject allotment are
indicative of the soil profile over the site any discrepancy between the profile detailed in the borelogs
and that observed during construction shall be referred to Global Testing for immediate attention.
5. MATERIALS LABORATORY TEST RESULTS
Soil Laboratory testing carried out on samples of the soil taken from the site gave the following results:
BOREHOLE BH1
DEPTH RANGE OF SAMPLE 500-800mm
LIQUID LIMIT (%) N/a
PLASTIC LIMIT (%) N/a
PLASTIC INDEX (%) N/a
LINEAR SHRINKAGE (%) N/a
INSTABILITY INDEX (%) N/a
SHRINK SWELL INDEX, Iss (%) 2.9
PREDICTED SURFACE MOVEMENT 40-50mm
Please note that the Plasticity Index (PI) determined by the Atterberg Test may be correlated to an
Instability Index (Ips)with reference to the results of extensive testing carried out by others, notably, Dr
P Mitchell, ‘Footings for Small Scale Domestic Structures,’ March 1990.
Yours Sincerely,
(Luke Wade - Office Manager)
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LIMITATIONS
Recommendations given in this report are based on the information supplied by the client regarding the
proposed building construction in conjunction with the findings of the investigation. Any change in
construction type, building location or omission in the client supplied information, may require addi-
tional testing and/or make the recommendations invalid.
The recommendations herein identify a target soil stratum into which the footings are to be founded.
The target stratum has been located by the depth in mm of the target stratum's upper horizon boundary
below the existing ground surface level at the time of the site investigation. Any cutting or filling works
and any surface erosion or deposits subsequent to the site investigation, will alter the measured location
of the stratum relative to the surface. Where required, the author should be notified in such cases to
confirm the location of the target stratum.
The description of the soil given in the Soil Profile section of this report is intended as a brief overview
of the soil's primary constituents. For a detailed classification of the soil, the reader should refer to the
Soil Profile Reports and/or Borehole Reports attached to this report.
Every reasonable effort has been made to locate the test sites so that the borehole profiles are repre-
sentative of the soil conditions within the area investigated. The client should be made aware however,
that exploration is limited by time available and economic restraints. In some cases, soil conditions can
change dramatically over short distances, therefore, even careful exploration programs may not locate
all the variations.
If soil conditions different from those shown in this report are encountered or are inferred from other
sources, then the author must be notified immediately.
This report may not be reproduced except in full. The information and drawings provided with this
report shall only be used and will only be applicable for the development shown on the client supplied
information provided for this site.
Any dimensions, contours, slope directions and magnitudes shown on the Test Locality Plan shall not
be used for any building construction or costing calculations. The purpose of the plan is to show ap-
proximate location of field tests only.
Any changes made to these recommendations by persons unauthorised by the author will legally be
interpreted as that person assuming the responsibility for the long-term performance of the footing sys-
tem.
The recommendations contained in this report have not taken into consideration the long-term effects
of any previous, current or potential subsurface work by mining companies or potential slope instability
problems. At the time of writing this report neither our client (nor his agent) nor the local authority had
made the author aware that these problems may be affecting this allotment. If a mining subsidence or
slope stability assessment is required for this allotment, the recommendations of a suitably qualified
geotechnical engineer should be sought.
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SOIL PROFILE REPORT
CLIENT: MACKY GROUP AUTHORISED MACKY GROUP
BY:
PROJECT: 15 & 17 MYALL STREET, DATE TESTED: 13/06/2025
COOROY JOB NO: 25-0664
Drilling Method: Jacro 105 100mm. Borehole
No.1
Depth Description PENET. Est. Bearing
(blows per 100mm)
(mm) Capacity
1 2 3 4 (kPa)
0 FILL/ CLAYEY SAND (SC)- Fine to me-
dium sand, grey-brown, trace fine gravel,
moist, loose
100 1 50
200 1
300 2
400 SANDY CLAY (CH)- High plasticity, 3 100
brown, fine to medium sand, w~PL, stiff
500 2
600 3
700 3
800 3
900 3
1000 3
1100 SANDY CLAY (CH)- High plasticity, brown 5 150
mottle orange-brown, fine to medium sand,
w~PL, very stiff
1200 10
1300 18
1400 SANDY CLAY (CH)- High plasticity, brown >20 >150
mottle orange-brown, fine to medium sand,
w~PL, hard
1500
1600
1700
1800
1900
2000 ROCK (XW)- Extremely weathered, pale >200
brown mottled pale grey, very low strength
2100
2200
2300
2400
2500
-
4500 Bore Terminated – Depth Achieved
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SOIL PROFILE REPORT
CLIENT: MACKY GROUP AUTHORISED MACKY GROUP
BY:
PROJECT: 15 & 17 MYALL STREET, DATE TESTED: 13/06/2025
COOROY JOB NO: 25-0664
Drilling Method: Jacro 105 100mm. Borehole
No.2
Depth Description PENET. Est. Bearing
(blows per 100mm)
(mm) Capacity
1 2 3 4 (kPa)
0 FILL/ CLAYEY SAND (SC)- Fine to me-
dium sand, grey-brown, trace fine gravel,
moist, loose
100 2 75
200 2
300 2
400 1
500 SANDY CLAY (CH)- High plasticity, 2 100
brown-grey, fine to medium sand, w~PL,
stiff
600 2
700 2
800 SANDY CLAY (CH)- High plasticity, 2 100
brown mottle orange-brown, fine to medium
sand, w~PL, stiff
900 3
1000 3
1100 3
1200 SANDY CLAY (CH)- High plasticity, or- 4 150
ange-brown mottle pale brown, fine to me-
dium sand, w~PL, stiff
1300 4
1400 4
1500 SANDY CLAY (CH)- High plasticity, pale 4 150
grey mottled orange-brown, fine to medium
sand, w~PL, stiff
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
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2800
2900
3000 SANDY CLAY (CH)- High plasticity, or- 150
ange-brown mottled pale grey, fine to me-
dium sand, w~PL, stiff
3100
3200
3300
3400
3500
3600
3700
3800
3900
4000
4100
4200
4300
4400
4500 Bore Terminated – Depth Achieved
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QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
SOIL PROFILE REPORT
CLIENT: MACKY GROUP AUTHORISED MACKY GROUP
BY:
PROJECT: 15 & 17 MYALL STREET, DATE TESTED: 13/06/2025
COOROY JOB NO: 25-0664
Drilling Method: Jacro 105 100mm. Borehole
No.3
Depth Description PENET. Est. Bearing
(blows per 100mm)
(mm) Capacity
1 2 3 4 (kPa)
0 FILL/ CLAYEY SAND (SC)- Fine to me-
dium sand, brown-grey, moist, medium
dense
100 3 100
200 3
300 SANDY CLAY (CH)- High plasticity, pale 2 100
brown mottled brown, fine to medium sand,
w~PL, firm to stiff
400 2
500 2
600 2
700 1 75
800 2
900 2
1000 SANDY CLAY (CH)- High plasticity, pale 3 100
brown mottled brown, fine to medium sand,
trace fine to medium gravel, w~PL, stiff
1100 3
1200 3
1300 4
1400 SANDY CLAY (CH)- High plasticity, pale 10 150
brown mottled brown, fine to medium sand,
trace fine to medium gravel, w~PL, very
stiff
1500 10
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
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PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
2700
2800
2900
3000 SANDY CLAY (CH)- High plasticity, or- 150
ange-brown mottled brown, fine to medium
sand, moist-wet, very stiff
3100
3200
3300
3400
3500
3600
3700
3800
3900
4000
4100
4200
4300
4400
4500 Bore Terminated – Depth Achieved
Page | 8 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 20
QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
SOIL PROFILE REPORT
CLIENT: MACKY GROUP AUTHORISED MACKY GROUP
BY:
PROJECT: 15 & 17 MYALL STREET, DATE TESTED: 13/06/2025
COOROY JOB NO: 25-0664
Drilling Method: Jacro 105 100mm. Borehole
No.4
Depth Description PENET. Est. Bearing
(blows per 100mm)
(mm) Capacity
1 2 3 4 (kPa)
0 FILL/ CLAYEY SAND (SC)- Fine to me-
dium sand, grey-brown, moist, medium
dense
100 4 100
200
300 3
400 SANDY CLAY (CH)- High plasticity, 3 100
brown, fine to medium sand, w~PL, stiff
500 3
600 2
700 2
800 2
900 2
1000 SANDY CLAY (CH)- High plasticity, pale 3 100
grey mottled brown, fine to medium sand,
w~PL, stiff
1100 3
1200 SANDY CLAY (CH)- High plasticity, pale 3
grey mottled brown, fine to medium sand,
w~PL, stiff
1300 6
1400 8 150
1500 10
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
Page | 9 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 21
QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
3000 SILTY CLAY (CH)- High plasticity, brown 150
mottled pale-grey, fine to medium sand,
w~Pl, very stiff
3100
3200
3300
3400
3500
3600
3700
3800
3900
4000
4100
4200
4300
4400
4500 Bore Terminated – Depth Achieved
Page | 10 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 22
QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
SOIL PROFILE REPORT
CLIENT: MACKY GROUP AUTHORISED MACKY GROUP
BY:
PROJECT: 15 & 17 MYALL STREET, DATE TESTED: 13/06/2025
COOROY JOB NO: 25-0664
Drilling Method: Jacro 105 100mm. Borehole
No.5
Depth Description PENET. Est. Bearing
(blows per 100mm)
(mm) Capacity
5 6 7 8 (kPa)
0 FILL/ CLAYEY SAND (SC)- Fine to me-
dium sand, grey-brown, moist, loose
100 2 75
200 2
300 2
400 1
500 SANDY CLAY (CH)- High plasticity, 2 100
brown, fine to medium sand, w~PL, stiff
600 3
700 SANDY CLAY (CH)- High plasticity, brown 5 150
mottled orange-brown, fine to medium sand,
w~PL, very stiff
800 5
900 5
1000 4
1100 5
1200 5
1300 6
1400 6
1500 SANDY CLAY (CH)- High plasticity, pale 8 >150
grey mottled brown, fine to medium sand,
moist, very stiff
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
-
4500 Bore Terminated – Depth Achieved
Page | 11 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 23
QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
SOIL PROFILE REPORT
CLIENT: MACKY GROUP AUTHORISED MACKY GROUP
BY:
PROJECT: 15 & 17 MYALL STREET, DATE TESTED: 13/06/2025
COOROY JOB NO: 25-0664
Drilling Method: Jacro 105 100mm. Borehole
No.6
Depth Description PENET. Est. Bearing
(blows per 100mm)
(mm) Capacity
5 6 7 8 (kPa)
0 FILL/ CLAYEY SAND (SC)- Fine to me-
dium sand, grey-brown, moist, loose
100 1 50
200 2
300 2
400 SANDY CLAY (CH)- High plasticity, 2 100
brown, fine to medium sand, w~PL, stiff
500 2
600 3
700 2
800 SANDY CLAY (CH)- High plasticity, 3 100
brown mottled orange-brown, w~PL, stiff
900 3
1000 3
1100 3
1200 SANDY CLAY (CH)- High plasticity, 5 150
brown mottled orange-brown, w~PL, very
stiff
1300 5
1400 5
1500 5
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
3000 SANDY CLAY (CH)- High plasticity, or- 150
ange-brown mottled pale grey, fine to me-
dium sand, moist-wet
Page | 12 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 24
QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
3100
3200
3300
3400
3500
3600
3700
3800
3900
4000 Groundwater table
4100
4200
4300
4400
4500 Bore Terminated – Depth Achieved
Page | 13 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 25
QBCC #:15288478
PH: 07 54 740 900
3/53 Gateway Drive, Noosaville 4566
[email protected]
Site- 15 & 17 MYALL STREET, COOROY
Page | 14 Borelogging in accordance with AS1726-2017 Geotechnical Site Investigations
25-0664
Page 26
N
EXISTING DRIVING
BH5 BH4
PN5 PN4
EXISTING
SATELLITE IMAGERY
DWELLING
LEGEND
MYALL STREET
BH6 BHx = BOREHOLE LOCATION
PN6
PNx = DYNAMIC CONE PENETROMETER
LOCATION
TREES
EXISTING
SHED
EXISTING
DWELLING
BH2
PN2
BH1
PN1 BH3
PN3
SITE PLAN
SCALE: 1 : 250
SITE CLASSIFICATION CLIENT DETAILS PROJECT DETAILS DRAWING TITLE JOB No. 25/0664
EFFLUENT DESIGN
SOUTH EAST QLD
THE MACKY GROUP 15 & 17 MYALL STREET, COOROY, TEST LOCATION PLAN DRG No. 301
[email protected]
ABN : 84 653 312 997 QLD 1
DRAWN: JA DATE: 13/06/2025 SCALE:As indicated@A3 REVISION
Page 27
ABN 51 640 311 842
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Sunshine Coast | Brisbane | Gold Coast
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arcosgroup.com.au
Sunshine Coast | Brisbane | Gold Coast