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Attachment 12 - Geotechnical Investigation Report
GEOTECHNICAL INVESTIGATION
Proposed Retirement
Development
Myall Street, Cooroy
Report for Ruby Developments Pty Ltd
Report 19071-001-Rev0
17 May 2019
Tectonic Geotechnical Pty Ltd
PO Box 899 Buderim Qld 4556
Office: (07) 5478 9016 Email: [email protected]
www.tectonicgeo.com.au
A.B.N. 83 165 727 828
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Page 2
PROPOSED RETIREMENT DEVELOPMENT
MYALL STREET, COOROY
Document Review
Document No. Revision Prepared By Reviewed By Date Issued
001 0 Robert Gibb Ashley Davey 17 May 2019
Report Distribution
Document Revision Method of Delivery Issued To
Grant Epple
001 0 Electronic
([email protected])
Prepared By: Reviewed By:
Robert Gibb BSc (Hons) Ashley Davey RPEQ 8159
Engineering Geologist Director/Principal Geotechnical Engineer
17 May 2019
Report No. 19071-001-Rev0 i
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Executive Summary
This report details the results of a geotechnical investigation undertaken for a proposed retirement
development at Myall Street, Cooroy. The investigation was performed by Tectonic for Ruby Developments
Pty Ltd. The investigation comprised drilling of boreholes at 13 locations, together with geotechnical
laboratory testing. This report summarises the results of the investigation and provides general geotechnical
recommendations regarding earthworks, footings, pavements, retaining walls and drainage.
According to preliminary layout plans (supplied subsequent to fieldwork being completed), the proposed
development will include around 175 standard residential lots spread across the entirety of the site area. A
two-storey club house with sporting facilities, including a swimming pool, a bowling green and a tennis court
at ground level is proposed central to the eastern boundary. The overall site would be accessed off Myall
Street, via a two lane driveway to the north-western corner, which appears to also link to a future club house
and car parking for the Cooroy Golf Club. Crossing of an existing creek which cuts across the north-western
corner of the site will be required to facilitate this access.
Large scale, bulk earthworks are anticipated, with the majority of the site being in cut (up to 6.5 m deep);
along with filling of around 3 m generally, with localised embankments up to 5 m height in the vicinity of bio-
basins proposed to the north and south of the overall site.
Boreholes encountered relatively consistent subsurface profiles, featuring topsoil to around 0.2 m below
ground level (BGL); overlying mostly stiff, high plasticity silty clays, becoming very stiff (or stiffer) below
about 1 m depth. Possible rock was encountered in one borehole (BH13) in the southern part of the site at
2.1 m BGL. We note that details regarding the scale of the proposed bulk earthworks were not available at
the time of planning and undertaking our assessment, and while weathered rock was not encountered
generally within the scope of the boreholes (generally to 3 m BGL), the presence of weathered rock cannot
be discounted within the depth of the proposed cut earthworks (up to about 6.5 m).
Standing groundwater was recorded in the lower lying ground in the north-western part of the site at 0.65 m
BGL; with seepages noted on the flanks of the higher ground at between 0.5 m and 0.75 m BGL. Across the
cut areas therefore, minor groundwater seepages may be possible within the upper 1 m of the subsurface
profile, and from deeper horizons. Excavations for the proposed bio-basins to the north and south of the site
may experience the groundwater table/inflow within 1 m of the ground surface, resulting in more significant
dewatering.
Excavations within the natural soils should generally be achievable using conventional earthmoving plant, to
the maximum depth of the investigation boreholes. However, there is an outstanding risk that rock may be
encountered across significant portions of the proposed cut areas. Depending on the weathering profile,
strength and jointing characteristics of the rock, localised ripping (with excavators); larger scale heavy ripping
(with dozers); or indeed pneumatic breaking may be required.
In cut areas where rock is not exposed at the foundation subgrade, an AS2870 site classification of Class H1
is recommended, and Class H2 in fill areas. Normally dimensioned, high-level footings should be appropriate
for all proposed structures, subject to Level 1 inspection and testing to produce ‘controlled’ fill. Footings
should found in to the following strata using recommended design allowable bearing capacities of 100 kPa
(Level 1 controlled fill); 200 kPa (natural very stiff clay); or 400 kPa (very low strength rock).
Design of pavements on natural clay subgrades or site won Level 1 controlled fill should be based on a CBR
value of no more than 3%.
Due to the difference in information supplied with the project brief, compared to more recent earthworks
proposals provided to us; the subsurface information gained during this investigation, is inadequate in
addressing ground conditions in several key areas for the development. These relate to excavatability,
rockhead levels; groundwater levels; lack of specific subsurface information at the bridge and clubhouse
sites; and global stability for large retaining walls. Therefore, a supplementary geotechnical investigation is
proposed, as detailed in this report.
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Table of Contents
1.0 INTRODUCTION ........................................................................................................................................................ 1
2.0 PROPOSED DEVELOPMENT ................................................................................................................................... 1
3.0 SITE DESCRIPTION .................................................................................................................................................. 2
4.0 METHOD OF INVESTIGATION ................................................................................................................................. 5
4.1 Fieldwork ...................................................................................................................................................... 5
4.2 Laboratory Testing ........................................................................................................................................ 5
5.0 INVESTIGATION FINDINGS ..................................................................................................................................... 6
5.1 Geology ........................................................................................................................................................ 6
5.2 Subsurface Conditions.................................................................................................................................. 6
5.3 Geotechnical Laboratory Test Results .......................................................................................................... 7
6.0 ENGINEERING ASSESSMENT ................................................................................................................................ 8
6.1 Earthworks .................................................................................................................................................... 8
6.1.1 Site Preparation ...................................................................................................................................... 8
6.1.2 Trafficability ............................................................................................................................................. 8
6.1.3 Excavations ............................................................................................................................................. 8
6.1.4 Filling....................................................................................................................................................... 9
6.2 Building Foundations .................................................................................................................................. 10
6.2.1 Indicative Site Classification.................................................................................................................. 10
6.2.2 Footing Design ...................................................................................................................................... 11
6.2.2.1 Residential Allotments ....................................................................................................................... 11
6.2.2.2 Club House ........................................................................................................................................ 11
6.2.2.3 General .............................................................................................................................................. 11
6.3 Retaining Structures ................................................................................................................................... 12
6.4 Pavement Design Parameters .................................................................................................................... 13
6.5 Groundwater and Drainage ........................................................................................................................ 13
6.6 Supplementary Site Investigation ............................................................................................................... 14
7.0 LIMITATIONS .......................................................................................................................................................... 14
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TABLES
Table 1: Summary of Atterberg Limits, Percent Fines, and Shrink-Swell Index Laboratory Results ................................... 7
Table 2: Summary of CBR Laboratory Results ................................................................................................................... 7
Table 3: Effect of inert engineered fill in reducing characteristic ground surface movement ............................................. 10
Table 4: Retaining Structure Design Parameters .............................................................................................................. 12
TEXT FIGURES
Text Figure 1: Extract from layout masterplan (courtesy Westera) ..................................................................................... 1
Text Figure 2: Extract of DSQ Survey Plan showing recent aerial image and 0.5 m contours ............................................ 2
Text Figure 3: View from borehole BH5/low-lying ground looking south ............................................................................. 3
Text Figure 4: View looking north / downslope from higher ground on site (approx to borehole BH8) ................................ 3
Text Figure 5: Looking north from lower lying ground at southern boundary....................................................................... 3
Text Figure 6: View of proposed RV compound area to north-west of site (borehole BH10), looking east towards
creek .................................................................................................................................................................. 4
Text Figure 7: 4WD ute auger drill rig bogged to north-west of site; and creek in north-west corner .................................. 4
FIGURES
Figure 1: Site Plan
APPENDICES
APPENDIX A
Borehole Reports and Explanatory Notes
APPENDIX B
Geotechnical Laboratory Test Certificates
APPENDIX C
Limitations
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1.0 INTRODUCTION
This report details the results of a geotechnical investigation undertaken for a proposed retirement
development at Myall Street, Cooroy. The investigation was performed by Tectonic Geotechnical Pty Ltd
(Tectonic) for Ruby Developments Pty Ltd, in general accordance with our Proposal P18099-Rev0 dated
25 March 2019. Westera Partners Pty Ltd (Westera) are the consulting civil and structural engineers.
The investigation comprised drilling of boreholes at 13 locations, together with geotechnical laboratory
testing. This report summarises the results of the investigation and provides geotechnical recommendations
regarding earthworks, footings, pavements, retaining walls and drainage.
2.0 PROPOSED DEVELOPMENT
A preliminary layout plan was supplied to us (Westera, Ref. S19/007 P, dated April 2019 [with annotations 9
May 2019]) and indicates that the proposed development will yield around 175 standard residential lots
(approximately 14 m x 21 m in size) spread across the entirety of the site area. A club house with sporting
facilities, including a swimming pool, a bowling green and a tennis court at ground level is shown central to
the eastern boundary. It is understood that the clubhouse is likely to be a two-storey masonry structure.
The overall site would be accessed off Myall Street, via a two lane driveway to the north-western corner,
which appears also to link with a future club house and car parking for the Cooroy Golf Club. Crossing of an
existing creek which cuts across the north-western corner of the site will be required to facilitate this access.
Internal access roads are to be spread amongst the residential lots, with landscaped areas to the fringes.
Preliminary earthworks annotations (Ref. Text Figure 1 below), indicate that large scale bulk earthworks are
proposed, with the majority of the site being in cut (up to 6.5 m); along with filling of around 3 m generally,
with localised embankments up to 5 m height in the vicinity of bio basins proposed to the north and south of
the overall site.
Text Figure 1 below shows the site layout with preliminary earthworks annotations.
Text Figure 1: Extract from layout masterplan (courtesy Westera)
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3.0 SITE DESCRIPTION
The subject site is described as Lots 2 and 3 on SP115864, covering areas of 2.23 and 7 ha respectively
(Ref. Text Figure 2 below). Overall, the site is approximately rhomboidal in shape, bounded by Myall Street
along the western boundary, and otherwise Cooroy Golf Club, which consisted of undulating ground.
The site mostly comprised open, grassed ground. A creek was noted to be cutting through the north-western
corner, with moderately sized, mature trees flanking the incised banks. Water was noted in the creek at the
time of the investigation.
Topographically the site consisted of a rounded knoll, orientated approximately east to west; and continuing
north-easterly towards the eastern boundary, as a gently rounded spur. Slopes on the site fall to the north-
west centrally to the site, and to the south/south-east in the south of the site. Low-lying, and flatter ground
was located to the north-east, proximal to the location of the creek banks; and along the southern boundary
(where a natural overland flow path is present, Ref. Text Figure 2). Low-lying ground was noted to be soft
underfoot during the investigation, with the 4WD ute mounted drill rig becoming bogged in around the top
0.3 m to 0.4 m depth, of softened upper soils (Ref. Figure 1 at the end of the report text, and Text Figure 7
below).
Ground slopes on site were typically between about 5° and 8° (9 % and 14 %), recorded using a hand-held
clinometer during our walkover assessment. Lower lying portions of the site were measured at 2° to 3°
(3 % to 5 %); with the creek banks at between 20° and 30° (36 % and 58 %). A site survey drawing supplied
with the project brief (DSQ Land Surveyors, Dwg. No. 13422-DTM-01, Rev A, dated 20 December 2018)
illustrates the topographical conditions on site; overlain on a recent aerial photograph. An extract of this is
presented below in Text Figure 2.
Cooroy Golf Club
Overall site boundary
Possible overland flow path
Text Figure 2: Extract of DSQ Survey Plan showing recent aerial image and 0.5 m contours
Site conditions at the time of our assessment are presented overleaf in Text Figures 3 to 7.
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Text Figure 3: View from borehole BH5/low-lying ground looking south
Text Figure 4: View looking north / downslope from higher ground on site (approx. to borehole BH8)
Text Figure 5: Looking north from lower lying ground at southern boundary
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Text Figure 6: View of proposed RV compound area to north-west of site (borehole BH10), looking east towards creek
Text Figure 7: 4WD mounted auger drill rig bogged to north-west of site; and creek in north-west corner
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4.0 METHOD OF INVESTIGATION
4.1 Fieldwork
13 boreholes (designated BH1 to BH13) were drilled using a 4WD mounted drilling rig owned and operated
by Ground Drill, mostly to a target depth of 3 m below ground level (BGL). Borehole drilling refusal was
encountered in borehole BH13 only, to the south-west of the site, on possible weathered rock at 2.3 m BGL.
Boreholes were spread across the site area to give a general representation of the site conditions across
the proposed development areas. The original project brief indicated that the proposed clubhouse would be
in the north of the site (Ref. Jared Poole Design Dwg. No. BP1074/SK1.01, Issue C, dated January 2019)
and hence deeper drilling to 6 m BGL was undertaken in that vicinity. Similarly at the time of commissioning
the investigation, a two lane driveway was not proposed along the northern boundary; and neither were
such significant earthworks anticipated (thus the majority of boreholes being terminated at 3 m BGL).
In situ testing comprised dynamic cone penetrometer (DCP) tests adjacent to all locations, and at selected
intervals within all boreholes. Pocket penetrometer (PP) testing was carried out on clay samples recovered
from the augers, and on undisturbed (U50) tube samples.
Disturbed and undisturbed soil samples were taken from the boreholes for laboratory testing. Boreholes
were typically drilled using a 100 mm diameter solid flight auger. Four bulk disturbed samples from the likely
pavement subgrade materials were recovered for California Bearing Ratio (CBR) testing, using a 300 mm
diameter auger.
Fieldwork was undertaken in the presence of an experienced engineering geologist from Tectonic between
on 10 April 2018. The geologist was responsible for logging soil profiles in accordance with AS1726
Geotechnical site investigations, making groundwater observations, and recovering soil samples. All
boreholes were backfilled with auger cuttings on completion, with excess spoil slightly mounded at the
surface. The borehole drilling was combined with a site walkover survey including observations of soil and
rock exposures, surface drainage conditions, topography, evidence of erosion, and vegetation
coverage/condition.
Borehole reports are attached in Appendix A, together with explanatory notes. Borehole locations are
shown on Figure 1, attached at the end of this report.
4.2 Laboratory Testing
Undisturbed and disturbed soil samples were dispatched to SMEC Pty Ltd, a NATA accredited geotechnical
laboratory located in Birtinya, for geotechnical testing. Laboratory testing was undertaken in accordance
with Australian Standard AS1289 Method for Testing Soils for Engineering Purposes and comprised:
Three Shrink Swell Index (SSI) to enable estimation of characteristic ground surface movements;
One Atterberg Limits and Percent Fines for soil classification purposes;
Three CBR tests to enable an assessment of pavement design parameters.
Geotechnical laboratory results are discussed in Section 5.3. The geotechnical laboratory certificates are
attached in Appendix B.
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5.0 INVESTIGATION FINDINGS
5.1 Geology
The 1:100,000 scale Gympie Special Geological Map (Sheet 9445 & (part) 9545) indicates that the site is
underlain by “andesites and intrusives” of the late Traissic age Kulangor Member (pale blue stippled
shading); part of the North Arm Volcanics Group. The north of the site, in the vicinity of a mapped
watercourse, is noted to feature a covering of Quaternary age flood plain alluvium comprising “clay, silt, sand
[and] gravel.”
An extract from the relevant geological map is shown below in Text Figure 8.
Alluvium
Indicative site location
Kulangor Member
Text Figure 8: Extract from Gympie Special Geology Map
5.2 Subsurface Conditions
Detailed descriptions of the subsurface conditions encountered in the boreholes are provided in the borehole
reports attached in Appendix A, along with definition sheets which describe terms and abbreviations used in
the report.
Boreholes encountered relatively consistent subsurface profiles which can be summarised as follows:
Topsoil – brown, firm to stiff, high plasticity silty clays with organics and rootlets to around
0.2 m BGL; overlying
Residual Soils – mostly stiff, pale grey mottled red, high plasticity silty clays, becoming very stiff to
hard below around 1 m BGL.
Extremely Weathered (XW) Material/Weathered Rock – was only encountered in borehole BH13
(south-west of the site) at 2.1 m BGL; with auger refusal being encountered at 2.3 m BGL.
However, we note that while weathered rock was not encountered generally within the scope of the
boreholes to 3 m BGL across the site, the presence of weathered rock cannot be discounted within
the depth of the proposed cut earthworks (up to about 6.5 m BGL).
Possible alluvial deposits were also encountered in boreholes within the low-lying ground to the north-west,
and adjacent to the creek. These consisted of reworked stiff to very stiff residual clays, and medium dense
to dense clayey sands and gravels, to depths of about 3 m BGL, underlain by the abovementioned residual
soils.
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At the time of the investigation, groundwater seepage was recorded in isolated locations, generally indicating
seepage could be expected at around 0.5 m to 0.75 m BGL close to the toe of the immediate flanks to the
higher ground comprising the rounded knoll to the central-south parts of the site. Standing groundwater was
only recorded in borehole BH5, close to the creek in the lower lying ground, at a shallow depth of 0.65 m
BGL. Groundwater seepage may occur more extensively across the site, within permeable horizons such as
the sandy layers and fissures within the clay/weathered rock, particularly following periods of heavy or
prolonged rainfall.
5.3 Geotechnical Laboratory Test Results
Table 2 below summarises the results of laboratory tests conducted on soil samples recovered from select
boreholes. Laboratory test certificates are presented in Appendix B.
Table 1: Summary of Atterberg Limits, Percent Fines, and Shrink-Swell Index Laboratory Results
Atterberg Limits
Shrink-Swell
Liquid Plastic Plasticity Percent Fines
BH No. Depth (m) Index
Limit Limit Index (%)
(%, SSI)
(%) (%) (%)
BH2 1.0-1.17 - - - - 2.3
BH4 1.0-1.17 - - - - 2.0
BH5 1.0-1.15 - - - - 1.9
BH12 2.0-2.25 77 27 50 91 -
Notes: 1. Percent fines is the percentage of clay/silt fraction in the soil sample
2. “-“ denotes not scheduled
Laboratory testing indicates that the residual materials present on site are silty clays of high plasticity,
generally featuring very high ‘fines’ content. Shrink-swell index testing indicates that the residual clay
samples tested had a moderate reactivity to moisture content variations, however based on the liquid limit
and linear shrinkage shown for the borehole BH12 sample, it is possible that the material may be highly
reactive.
Table 3 below summarises the result of laboratory testing conducted on bulk soil samples recovered from
the likely pavement subgrade materials at boreholes BH3 and BH7 (based on information supplied in the
original project brief).
Table 2: Summary of CBR Laboratory Results
Optimum
Maximum Dry Field Moisture
BH No. Depth (m) Moisture CBR (%)
Density (t/m3) Content (%)
Content (%)
BH6 0.5-1.0 1.55 30.3 25.1 2.5
BH10 0.25-0.75 1.78 22.2 15.5 4.0
BH13 0.5-1.0 1.65 28.4 20.4 2.6
Testing conducted on the residual clay samples from boreholes BH6 and BH13 indicates low CBR values of
2.5 % and 2.6 %, respectively. Possible alluvial material, comprising reworked residual clays, gleaned a CBR
value of 4 % in borehole BH10. It is noted that the materials had moderate to high swell values, being around
2 % in all samples tested. Field moisture contents of the samples were all about 5 % to 8 % ‘wet’ of optimum
moisture content (OMC).
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6.0 ENGINEERING ASSESSMENT
6.1 Earthworks
It is anticipated that bulk earthworks for the site would include an extensive cut area across the majority of
elevated area, of up to 6.5 m depth. Filling of the lower lying ground the north and south is expected to
generally be in the order of 1 m to 4 m height, although in areas adjacent to the proposed bio-basins, it is
noted that retained embankments may range from 3 m to 5 m.
6.1.1 Site Preparation
Any existing vegetation and topsoil should be stripped away from the construction area. We anticipate
stripping depths on average of about 0.2 m BGL to remove existing topsoil, although deeper pockets may
exist. Historical aerial images indicate that some mature trees were present sporadically across the site until
at least early 2016. Therefore, any large roots or remaining stumps should also be ‘grubbed out’ as part of
the preparatory works. Organic rich topsoil materials and water softened upper soils (which may occur to at
least 0.3 m to 0.4 m BGL [Ref. Section 3.0 / Figure 1]) should not be used as structural fill or be placed under
pavement areas. Site-won material from the bulk earthworks cutting below these depths comprising high
plasticity, residual clay soils would be suitable for re-use as structural fill on site, subject to the suitable
moisture conditioning and handling (Ref. Section 6.1.4 below).
Following stripping, and excavation to the design levels, the subgrade may be expected to comprise mostly
high plasticity, residual silty clays; however in areas of the site currently at higher elevations, it is possible
that rock would be exposed.
Subgrade areas should be ‘proof rolled’ using a fully laden water cart or minimum 10 tonne roller in order to
identify any ‘soft spots’. Treatment of ‘soft spots’ may involve excavation and replacement with select fill or
tyning, appropriate moisture adjustment and compaction. Proof rolling must be carried out in the presence of
a suitably qualified and experienced RPEQ engineer.
The site should be graded to shed surface water runoff away from the construction area. It should be noted
that during wet weather, the natural soils present will tend to cause turbid stormwater run-off due to their
clayey nature. It is recommended that subgrades should be ‘sealed off’ by several passes of a smooth drum
roller at the end of each working day to minimise erosion potential during rainfall events. This would be
particularly pertinent given the presence of the creek in the north-west corner of the site.
6.1.2 Trafficability
Following stripping, the natural clay (and possible rock) subgrades should generally be trafficable for most
construction plant, however would tend to lose trafficability when affected by rainfall and from repetitive
wheel loadings, particularly from heavy rubber tyred plant. Placement of a granular select fill (e.g. minimum
CBR 15%) nominally 150 mm thick may be required on heavily trafficked areas (e.g. site entry/driveway and
laydown areas) to prevent softening of the clay subgrade and loss of trafficability.
Specific design would need to be carried out to determine working platform requirements for any heavy plant
(e.g. cranes or piling rigs), and a rock fill platform may be required.
6.1.3 Excavations
Excavations within the natural soils should generally be achievable using conventional earthmoving plant
(e.g. 20 to 30 tonne excavator(s) with toothed bucket attachments), to at least the maximum depth of the
investigation boreholes (generally 3 m depth).
The presence of very low strength (or stronger rock) was indicated in BH13, to the south-west of the site at
2.1 m BGL. The extent or nature of the weathered rock material has not been confirmed by the investigation.
Therefore, there is an outstanding risk that such material may be encountered across significant portions of
the proposed cut areas. Depending on the weathering profile, strength and jointing characteristics of the
rock, localised ripping (with excavators); larger scale heavy ripping (with dozers); or indeed pneumatic
breaking may be required (particularly in confined excavations (e.g. service trenches).
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To gain information on the rock material prior to the construction stage, a supplementary site investigation is
recommended (Ref. Section 6.6 below). This would be particularly relevant for the proposed club house and
adjacent pool, situated in an area of between 3 m and 6 m cut below the existing ground level.
Temporary (short term) unsupported cut batters may be constructed at a maximum slope of 1V:1H in the
natural soils and 2V:1H in low strength (or stronger) rock, provided that groundwater is not encountered.
Flatter batters may be required if groundwater seepage is encountered, or if earthworks are undertaken
during or immediately following a period of heavy rainfall.
Permanent cut/fill batters must be formed no steeper than 1V:2H. Steeper batters may be permissible in
weathered rock subject to inspection and confirmation by an RPEQ geotechnical engineer. Where such
battering is not possible, retention will be required.
Permanent soil or fill batters will require erosion protection such as revegetation by landscaping (e.g. topsoil,
jute matting and planting).
Any excavations required adjacent to existing structures (e.g. where construction is staged), will need to be
specifically designed to ensure that the structures are not adversely affected ('undermined').
6.1.4 Filling
Generally, the existing natural soils where free of deleterious materials (e.g. organics etc.), and weathered
rock (if broken down to a suitable particle size), are expected to be suitable for re-use as structural fill,
subject to appropriate moisture adjustment. Dependent upon weathering and defects, it may not be possible
to break down rock to a suitable particle size for placement in controlled fill (further site investigation is
recommended to mitigate this outstanding issue). Laboratory testing indicates that the natural residual soils
are very highly plastic, and thus may be difficult to handle and place, particularly if they are moist of optimum
moisture content (OMC). The site won high plasticity clays may be re-used as structural fill, subject to
appropriate moisture conditioning, however the impacts on site classification and pavement subgrades
should be considered.
Should importation of fill be required, it is recommended that such fill should comply with the following:
Minimum CBR of 10%
Maximum plasticity index of 15%
Shrink-swell index ≤ 1%
Maximum particle size of 100 mm
All imported and suitable site-won fill should be compacted at moisture contents within the range of ±2% of
OMC for compaction. Fill particles (e.g. weathered rock) greater than 150 mm must be excluded. Fill should
be placed in maximum 250 mm thick (loose thickness) layers and be compacted by repeated rolling to
achieve a dry density ratio of at least 95 % of the maximum Dry Density Ratio (Standard Compaction
method), or 70 % of the Dry Density Index for cohesionless fills (e.g. sands or gravels).
Confirmatory compaction testing must be carried out at regular intervals. Details for inspection and testing of
fill are given in Australian Standard AS 3798-2007 Guidelines on Earthworks for Commercial and Residential
Developments. We recommend placement of fill to Level 1 standards, as residential lots are present across
the majority of the proposed fill areas (based on the preliminary earthworks information, an extract of which
is presented in Text Figure 1); as the fill is to support building/slab loads within residential allotment
boundaries.
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6.2 Building Foundations
6.2.1 Indicative Site Classification
According to AS2870-2011 Residential Slabs and Footings, we have determined the site classification
resulting from the proposed range of earthworks (up to about 5 m of filling; up to 6.5 m of cutting).
In cut areas, where rock is not exposed, the natural clay soils are expected to have a classification of
Class H1, with an estimated characteristic surface movement (ys) equivalent to 40 mm to 50 mm. Due to the
highly plastic, and highly reactive nature of the potential site-won clay material, in fill areas ys ≈ 50 mm to
60 mm has been estimated, and consequently a classification of Class H2 is recommended as per AS2870.
To reduce the differential ground surface movements across the site earthworks could be designed and
constructed to use a fill ‘capping layer’ material, with a low reactivity to moisture content variation. Presented
in Table 3 are the required thicknesses of the inert fill capping layer required to achieve reduced ground
surface movements.
Table 3: Effect of inert engineered fill in reducing characteristic ground surface movement
Estimated characteristic ground surface
Thickness of inert engineered fill layer (m)
movement (mm)
0.5 40 to 50 (Class H1 equivalent)
≥0.75 30 to 50 (Class M equivalent)
The above would also apply where an inert fill capping layer was constructed in cut earthworks areas where
highly reactive natural clays are exposed at subgrade level, resulting in over-excavation and replacement.
Clean granular fill is not recommended for use in construction of the inert engineered fill platform. Any fill
should contain adequate fines so that water does not permeate through the inert fill platform and infiltrate
into the underlying highly reactive clays.
The imported low reactivity fill material would need to be relatively inert to moisture variation having a shrink-
swell index (Iss) value of less than 1 %. The appropriate select fill material is expected to have a plasticity
index of less than 15 %, and a fines content of no greater than 30 %. Confirmatory laboratory testing is
recommended to be undertaken on the potential fill material to assess the suitability for use on site. Site won
weathered rock, if available from deeper excavations, may be suitable for re-use as inert fill capping.
Movement sensitive structures would need to be positioned a minimum of 3 m from the edge of the fill
replacement areas to limit effects from potential shrink-swell behaviour of the adjacent natural ground.
17 May 2019
Report No. 19071-001-Rev0 10
Page 16
PROPOSED RETIREMENT DEVELOPMENT
MYALL STREET, COOROY
6.2.2 Footing Design
The proposed bridge along the northern boundary is noted in more recent information to be a two lane
structure. There was insufficient information gained during the investigation to provide footing
recommendations for this, and it is noted that near creek bank subsurface profiles can vary significantly due
to the interfingered nature of alluvial deposition. The bridge structure is therefore excluded from the scope of
this report, and further investigation is recommended to provide site-specific information at each of the
proposed abutment locations.
6.2.2.1 Residential Allotments
It is anticipated that the proposed residential allotments would feature small, one storey structures, built on a
slab on ground. Walls could be of masonry construction, or clad in lightweight materials; with roofing
comprising lightweight sheetmetal materials.
Where residential structures are to be sited in cut areas, normally dimensioned, conventional high level
footings should be taken to found a minimum of 0.5 m in to the natural residual soils. These are likely to be
very stiff in consistency, based on the results of the existing boreholes, and where such material is
encountered at the base of footing excavations, could be designed with an allowable bearing capacity of
200 kPa. Where rock is exposed in the excavation subgrade, footings should penetrate at least 0.3 m below
the exposed surface, and could be designed with an allowable bearing capacity of 400 kPa. Footing design
should also account for a site classification of Class H1.
In filled areas, provided the fill has been placed, tested and certified to Level 1 standards (notwithstanding
our general recommendations above in Section 6.1.4), it is recommended that footings found a minimum of
0.75 m below the finished fill surface (not including any landscaping fill or mulch). Footings so founded could
be designed with an allowable bearing capacity of 100 kPa, and should account for a site classification of
Class H2.
Residences on allotments close to the transition from cut to fill should seek to have all footings extend to the
same natural clay material, to prevent adverse differential movements (settlement and ys).
6.2.2.2 Club House
Final footing design recommendations would be dependent on the bulk earthworks plan, position of the
clubhouse and proposed construction.
Information supplied with the project brief indicates that the clubhouse would be a two-storey masonry
structure; and that a pool would be present to the north-east side. Based on the existing preliminary
earthworks information, and the limited subsurface information from the investigation, the following
preliminary recommendations are provided.
Generally speaking, normally dimensioned, conventional high level footings would be appropriate for the
structure. These could be taken to found either 0.5 m in to the very stiff (or stiffer) natural clay soils, using an
allowable bearing capacity of 200 kPa, or 400 kPa in very low strength rock. Greater bearing capacity may
be available in rock, subject to confirmation by further site investigation, and inspection of footing subgrades
during construction by a suitably qualified RPEQ geotechnical engineer.
6.2.2.3 General
A suitably qualified and experienced geotechnical engineer should inspect all footing excavations during
construction to confirm the foundation materials and allowable bearing capacity.
If any soil conditions encountered during construction are found to differ from those noted in the
geotechnical investigation, Tectonic should be notified immediately and an inspection carried out to
determine if changes to footing design are required.
17 May 2019
Report No. 19071-001-Rev0 11
Page 17
PROPOSED RETIREMENT DEVELOPMENT
MYALL STREET, COOROY
All footings should found such that they are not adversely affected by any adjacent excavations, batter
slopes, trenches, or retaining walls that are not designed to support loads. To minimise the potential for any
adverse interaction effects, footings should found at least below a plane extending 1 m horizontally from the
base of trenches/excavations/retaining walls, then rising up at 1V:1H. This requirement is illustrated in Text
Figure 9 below.
Text Figure 9: Footing depth required to minimise risk of undermining
6.3 Retaining Structures
Recent preliminary bulk earthworks and civil proposals supplied to us show that retaining structures of
between about 3 m and 5 m height are intended to the north and south of the site.
We have provided the following parameters, given in Table 4 below, to enable furthering of preliminary
design options. Once a specific arrangement has been proposed, this should be verified from a global
stability perspective. This would be particularly important for the retaining structure proposed to the north-
west of the site, above the existing creek bank.
Design for retaining walls could be carried out using a triangular pressure distribution applicable to the wall
type. The values in Table 4 assume that the walls are fully drained, and no allowance is included for
hydrostatic pressures, construction loading, up-slope footing loadings, the effects of sloping ground and
backfill compaction stresses.
Table 4: Retaining Structure Design Parameters
Unit Lateral earth pressure coefficients
Friction
weight
Retained material angle, Ø’
(kN/m3 Ka Ko
(Degrees) Kp
) (Cantilever wall) (Non-yielding wall)
Natural Very Stiff
1.8 28 0.36 0.53 2.77
(or stiffer) Clays
Controlled
1.8 26 0.39 0.56 2.56
Level 1 Fill*
Very Low Strength
2.1 35 0.27 0.43 3.69
(or stronger) Rock**
Note: * depends on fill material type and level of compaction.
** subject to confirmation during further site investigation (Ref. Section 6.6)
17 May 2019
Report No. 19071-001-Rev0 12
Page 18
PROPOSED RETIREMENT DEVELOPMENT
MYALL STREET, COOROY
6.4 Pavement Design Parameters
Pavement design will be dependent upon the subgrade materials present after earthworks.
Following earthworks, the pavement subgrade may comprise silty clays of mostly high plasticity, or rock.
CBR testing indicates that the existing natural clays have CBR values in the order of 2.5 % to 4 %. Where
future fill provides at least 500 mm deep coverage across the natural clays or in areas of cut exposing rock,
pavement design may be based upon the CBR value of these materials. Where rock is exposed following
bulk earthworks, a regulating layer of 150 mm minimum thickness is recommended below the main
pavement make-up.
Design of pavements on natural clay subgrades or site won controlled fill may be based on CBR value of no
more than 3 %. Proposed pavement subgrades must be ‘proof rolled’ and visually assessed by an
experienced RPEQ engineer to ensure no heaving or unacceptable subgrade deflection occurs. Should
heaving or deflection occur, excavation of ‘soft spots’ may be required, followed by reinstatement with
compacted select granular fill.
The recommended design CBR value is applicable to properly drained subgrades only, and must be
confirmed by subgrade inspection and testing, if necessary, by an experienced RPEQ engineer following
earthworks. ‘Properly drained subgrades’ require open graded drains, site grades that shed water and
prevent ponding, and subsurface drains adjacent to pavements.
6.5 Groundwater and Drainage
Groundwater was not encountered in the majority of the investigation boreholes, although noting that most
holes only extended to 3 m BGL during this investigation. A standing groundwater level was recorded in
borehole BH5 in the lower lying ground to the north of the site at 0.65 m BGL, following drilling; with
seepages noted on the flanks of the higher ground at between 0.5 m and 0.75 m BGL.
Across the cut areas therefore, minor groundwater seepages may therefore be possible within the upper 1 m
of the subsurface profile, and could also be present at the soil/rock interface, and deeper. If it is encountered
during construction, such seepage should be manageable using graded open surface drainage and/or a
submersible sump-pump(s). Excavations for the proposed bio-basin to the north of the site are shown in the
drawings to extend to around 2 m below the existing ground level. This is in the vicinity of borehole BH5
noted above, and therefore the groundwater table may be expected within 1 m of the ground surface. The
result of this would be that more significant dewatering may be required during construction.
Adequate site drainage must be installed to ensure that surface water runoff is directed away from
pavements, walls and footings. Subsurface disposal/infiltration of stormwater is not recommended due to
the potential to adversely affect the performance of footings and pavements, and the relatively impermeable
nature of the natural clays on site. Swale drains must be constructed upslope of any batters and retaining
walls.
Subsurface drainage must be installed behind any retaining walls in order to prevent the development of
hydrostatic pressure (e.g. slotted ‘aggi’ pipe wrapped in filter ‘sock’ placed in gravel backfill).
All stormwater should be piped or channeled to discharge to the future inter-allotment drainage network, or
at least 10 m downslope of any structure (including retaining walls) or fill embankments to the creek in the
north-west of the site.
17 May 2019
Report No. 19071-001-Rev0 13
Page 19
PROPOSED RETIREMENT DEVELOPMENT
MYALL STREET, COOROY
6.6 Supplementary Site Investigation
As has been mentioned above, due to the limited information supplied at the scoping stage with the project
brief; the subsurface information gained during this investigation, while giving a good general understanding
of the site is inadequate in addressing ground conditions in several key areas for the project. These relate to:
Rockhead levels across the site, which have implications for excavatability for bulk earthworks and
footings, and the pool adjacent to the clubhouse.
Groundwater levels, which are now more pertinent due to deeper than anticipated cuts; and
proposed bio-basin invert levels.
Lack of site-specific information at the proposed bridge and club house sites.
Global stability of large retaining structures, especially in close proximity to the creek banks to the
north-west.
Therefore, prior to advancing the project to the detailed/final design stage, we recommend that a
supplementary geotechnical investigation program is completed comprising the following:
Drilling of three boreholes to 7 m depth using a specialised rotary drilling rig capable of solid flight
augering, cased wash boring, and rock coring. Rock coring would be proposed when (and if) low
strength (or stronger) rock is encountered. These three boreholes would be positioned east to west
across the crest of the rounded knoll to the central-south part of the site, and at the proposed
clubhouse and pool location. One borehole would have a standpipe piezometer installed to gain an
understanding of groundwater levels for dewatering purposes in the areas of maximum proposed
cutting. In-situ testing comprising standard penetration testing (SPT) at selected depths would be
scheduled during the drilling. Subsequent laboratory testing could be completed on the recovered
rock core (if encountered) to determine excavatability characteristics.
Two boreholes (one at each abutment location) at either side of the proposed bridge structure.
These would be drilled using a specialised rig as specified above into rock (probable foundation for
bridge piles) to an estimated depth of 15 m BGL. One borehole would have a standpipe piezometer
installed to understand groundwater level differences compared to the creek level, and those close
to the proposed bio- basin excavation.
Detailed field mapping and visual appraisal of the existing creek bank geometry and stability;
together with conceptual advice regarding bank stabilisation measures (if required).
In addition a quantitative slope stability assessment would be proposed using the computer program
Slope/W to confirm that the proposed retaining walls will have a factor of safety against global slope
instability of at least 1.5 (including how this affects the in-situ stability of the existing creek bank).
7.0 LIMITATIONS
Your attention is drawn to the document “Limitations”, which is included in Appendix C of this report. The
statements presented in this document are intended to advise you of what your realistic expectations of this
report should be, and to present you with recommendations on how to minimise the risks associated with the
services provided by Tectonic for this project.
17 May 2019
Report No. 19071-001-Rev0 14
Page 20
Cooroy Golf Club Tectonic Geotechnical Pty Ltd
PO Box 899
Buderim Qld 4556
Office: 07 5478 9016
Email: [email protected]
BH3
BH1 PROJECT:
BH2 GEOTECHNICAL INVESTIGATION
BH6 PROPOSED RETIREMENT
DEVELOPMENT
BH4 MYALL STREET, COOROY
BH8
TITLE:
BH7
SITE PLAN
BH5
BH11
CLIENT:
BH9 RUBY DEVELOPMENTS PTY LTD
BH10
BH12
BH13 DRAWN: DATE:
RKG 17/05/2019
CHECKED: DATE:
ACD 17/05/2019
Myall Street
Myall Street
SCALE:
AS SHOWN
LEGEND:
APPROX. BOREHOLE
LOCATIONS
APPROX. SLOPE INCLINATION
AND DIRECTION
APPROX. AREA OF SOFTENED
SURFACE / BOGGY SOILS
ENCOUNTERED DURING
INVESTIGATION
PROJECT NO.: FIGURE: REV:
Note: Base image courtesy DSQ Land Surveyors (Dwg. No. 13422-DTM-01, Rev A, dated 20 December 2018) 0 20 40 60 80 m 19071 1 0
Page 21
PROPOSED RETIREMENT DEVELOPMENT
MYALL STREET, COOROY
APPENDIX A
Borehole Reports and Explanatory Notes
17 May 2019
Report No. 19071-001-Rev0
Page 22
Borehole No.
BH1
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491496.0 m E 7076881.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 110.50 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, brown with
CH organic material
St
Silty CLAY, high plasticity, brown and red, trace
organic material
U50 (RESIDUAL)
0.5-0.65m without organic material VSt
109.5
1
becoming pale grey and red
St
108.5
2
U50
2.0-2.15m
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:01 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
becoming dark red and pale grey, trace of fine
sized sub-rounded gravel
Not Encountered
107.5
AD/T
3 M Drill to 3 m
20/90mm Refusal
becoming dark brown
VSt
106.5
Augered to 4.0m
4
becoming grey and brown
105.5
Augered to 5.0m
5
becoming dark brown
104.5
6
Hole Terminated at 6.00 m
Target depth
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
Page 23
Borehole No.
BH2
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491545.0 m E 7076792.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 110.50 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, brown, HW
with organic material HW
Silty CLAY, HP, brown and dark brown, trace of
DS organic material
CH St
0.4-0.8m Silty CLAY, high plasticity, brown and red
(RESIDUAL)
109.5
1
U50
Not Encountered
becoming pale brown
1.0-1.17m
becoming pale grey and red
AD/T
M
108.5
2 VSt
DS
2.0-2.5m
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:01 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
becoming pale grey and red
107.5
3
Hole Terminated at 3.00 m
Target depth
106.5
4
105.5
5
104.5
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
Page 24
Borehole No.
BH3
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491632.0 m E 7076669.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 116.75 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, dark grey, HW
with organic material
DS CH Silty CLAY, high plasticity, dark brown and grey, F
0.25-0.75m trace of organic material
(RESIDUAL)
DS becoming brown and red
0.75-1.0m St to
115.8
1 VSt
U50
Not Encountered
1.0-1.11m
becoming pale grey and red
AD/T
M
DS
1.75-2.0m
114.8
2
VSt
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:01 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
113.8
3
Hole Terminated at 3.00 m
Target depth
112.8
4
111.8
5
110.8
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
Page 25
Borehole No.
BH4
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491687.0 m E 7076507.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 116.00 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, dark HW
brown, with organic material HW
CH St HW
Silty CLAY, high plasticity, brown, trace of organic HW
material
DS (RESIDUAL)
0.25-0.75m Silty CLAY, high plasticity, pale grey and red
VSt
115.0
1
U50
Not Encountered
becoming pale grey
1.0-1.17m H
Augered to 1.5m
AD/T
M
DS
1.5-1.75m
114.0
2 VSt
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:02 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
becoming pale grey and red
H
113.0
3
Hole Terminated at 3.00 m
Target depth
112.0
4
111.0
5
110.0
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
Page 26
Borehole No.
BH5
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491456.0 m E 7076837.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 108.00 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, brown,
St
with organic material
DS CH Silty CLAY, high plasticity, brown, trace of fine
0.25-0.5m sized rounded gravel
(Possible ALLUVIUM)
Silty CLAY, high plasticity, brown and red
Groundwater level at 0.6m on completion of drilling
107.0
1
U50 VSt
1.0-1.15m
M
becoming pale grey and red Augered to 1.5m
DS
1.5-2.0m
106.0
2 SC Clayey SAND, fine to coarse grained, pale grey,
DS high plasticity clay fines, with silt, trace of fine MD to
2.0-2.5m sized rounded gravel D
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:02 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
Augered to 2.4m
GC Clayey GRAVEL, fine to medium grained, brown 20/70mm
DS and red, with fine to coarse grained sand, high Refusal
2.5-3.0m plasticity clay
Inflow at 2.7 m
VD
105.0
AD/T
3
DS
3.0-3.5m
CH Silty CLAY, high plasticity, pale grey and red, fine
to coarse grained sand, fine sized sub-rounded
gravel Augered to 3.5m
CH Silty CLAY, high plasticity, pale grey and brown
(RESIDUAL)
104.0
20/80mm
4 Refusal
DS
4.25-4.75m W
VSt
becoming pale grey
103.0
5
Augered to 5.5m
>20
Refusal
102.0
6
Hole Terminated at 6.00 m
Target depth
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
Page 27
Borehole No.
BH6
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491560.0 m E 7076719.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 108.00 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, dark HW
St HW
brown, with organic material
CH Silty CLAY, high plasticity, brown, trace of organic
material
BDS (RESIDUAL)
0.5-1.0m becoming brown and red
107.0
1
Not Encountered
AD/T
M
VSt
106.0
2
becoming pale grey and red, trace of fine sized
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:03 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
sub-rounded gravel
becoming pale grey
105.0
3
Hole Terminated at 3.00 m
Target depth
104.0
4
103.0
5
102.0
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
Page 28
Borehole No.
BH7
Page 1 of 1
Engineering Log - Borehole Project No.: 19071
Client: Ruby Developments Commenced: 10/04/2019
Project Name: Proposed Retirement Complex Completed: 10/04/2019
Hole Location: Lot 2 & Lot 3 Myall Street, Cooroy Logged By: BZ
Hole Position: 491568.0 m E 7076642.0 m N MGA94 Zone 56 Checked By: ACD
Drill Model and Mounting: 4WD Auger Inclination: -90° RL Surface: 117.75 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: Ground Drill
Drilling Information Soil Description Observations
Relative Density
Classification
Pocket DCP TEST
Penetration
Consistency
Graphic Log
Samples Material Description (AS 1289.6.3.2-1997)
Penetrometer
Recovery
Condition
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
Remarks secondary and minor components, colour
Water
RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
CH Silty CLAY (TOPSOIL), high plasticity, dark HW
brown, with organic material
CH St
Silty CLAY (RESIDUAL), high plasticity, brown,
trace of organic material
M
DS becoming red
0.5-0.75m
116.8
1
Not Encountered
becoming pale brown and red
AD/T
VSt
becoming pale grey and red
115.8
2 D
TECTONIC 2.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 19071.GPJ <<DrawingFile>> 17/05/2019 12:03 10.0.000 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 2.00.2 2016-10-13 Prj: Tectonic 2.00 2016-02-16
114.8
3
Hole Terminated at 3.00 m
Target depth
113.8
4
112.8
5
111.8
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit No resistance Level (Date) U - Undisturbed Sample D - Dry VS - Very Soft
RR - Rock Roller ranging to D - Disturbed Sample M - Moist S - Soft
RD - Rotary Drilling refusal Inflow SPT - Standard Penetration Test W - Wet F - Firm
NMLC -Rock Core Partial Loss VSt - Very Stiff
HA - Hand Auger Complete Loss H - Hard
Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols and < PL MD - Medium Dense
Core recovered (hatching Soil Descriptions
indicates material) = PL D - Dense
Based on Unified Soil < PL VD - Very Dense
Core loss
Classification System
The text continues on page 29.