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Slope Stability Report 26-5-2019 OPW19-0193
Trubuilt
Slope Risk Assessment Report
91 Ewarts Road, Cooran
GAG16011
PO Box 1455
Noosaville Qld 4566 26 May 2019
Ph: 0417 982 768
Email: [email protected] LEONTAKIANAKOS-R-001
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Disclaimer
This report has been prepared on behalf of and for the exclusive use of Trubuilt, and is subject to and issued in
accordance with the agreement between Trubuilt and Grinceri and Associates Pty Ltd. Grinceri and Associates
Pty Ltd accepts no liability or responsibility whatsoever for it in respect of any use of or reliance upon this
report by any third party.
Copying this report without the permission of Trubuilt or Grinceri and Associates Pty Ltd is not permitted.
REPORT LEONTAKIANAKOS-R-001 - SLOPE RISK ASSESSMENT REPORT
REV DESCRIPTION ORIG REVIEW DATE CLIENT DATE
APPROVAL
0 Final Issue 26 May 2019 N/A
M Grinceri M Grinceri
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TRUBUILT SLOPE RISK ASSESSMENT REPORT CONTENTS 1. INTRODUCTION ................................................................................................................................ 1 2. DESKTOP STUDY AND DESCRIPTION OF SITE CONDITIONS ............................................................. 3 3. ASSESSMENT OF LAND STABILITY .................................................................................................... 8 4. RECOMMENDATIONS FOR DEVELOPMENT OF SITE ...................................................................... 12 5. REFERENCES ................................................................................................................................... 17 6. IMPORTANT INFORMATION ON INTERPRETATION, USE AND LIABILITY OF THIS REPORT ............ 18 APPENDIX 1– SITE PLAN, BOREHOLE LOGS AND GEOLOGICAL SECTIONS APPENDIX 2– PHOTOGRAPHIC PLATES LEONTAKIANAKOS-R-001 Page ii 26 May 2019
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1. INTRODUCTION
This report presents the results of a field mapping and slope risk assessment undertaken on 91 Ewarts Road,
Cooran on behalf of Trubuilt. The work was undertaken to the scope of works and the terms and conditions
contained within the GA Geotechnical’s Engineering Services Agreement with Trubuilt.
This investigation is and risk assessment is undertaken to the requirements of AS1726-2017, AGS2007 and the
geotechnical site investigation requirements of Noosa Shire Council. Noosa Shire Council online mapping
application shows that the site falls within the Landslide Risk overlay map on the Noosa Shire Natural Hazard
Overlay Map.
Trubuilt has supplied the following documents for this investigation:
• Site plan and sections for the proposed development.
Note that due to the site of the site, the investigation and findings of this report are limited to the area
enclosed within the red rectangle shown on DWG-01.
1.1 Details of the Proposed Development
The proposed development shall comprise a timber pole home with minor cut and fill earthworks.
1.2 Site Location and Description
The site is located at Lot 61 M371155, 91 Ewarts Road, Cooran. The site comprises an approximately
rectangular rural lot that is about 645,983m2.
The site encompasses several east-west trending, steep sided valleys. The proposed development is limited to
a small area in the north-east corner of the site.
1.3 Method and Scope of Investigation
In order to address the requirements of the Noosa Shire Council planning scheme with respect to
developments on steep or landslide prone land the following investigation methodology was utilised:
• Three hand auger boreholes to a maximum depth of 1.9m bgl to provide further information on the
subsurface conditions of the site, DCP testing was undertaken adjacent to each borehole;
• Site walkover and mapping of key site features, geological outcrops, geomorphology and evidence of
land instability and/or erosion;
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• Measurement of slope profiles through the proposed development for the preparation of geological
models;
• Drone photography and mapping of the site;
• Photography of key site features.
Following the fieldwork this report was prepared to include the following:
• Description of the proposed development;
• Desktop study of the site development and use history, historical instability and general conditions;
• Results of the site investigation including subsurface and groundwater conditions, site topography,
site drainage and evidence of erosion or instability;
• Interpreted geology of the site;
• Assessment of any site constraints to the proposed development;
• Assessment of the effect of the proposed development on the stability of the site to the requirements
of AGS2007;
• Recommendations for foundation design and construction, site preparation, earthworks and site
drainage.
The position of key features was identified using a handheld GPS to an accuracy of about ±3m, correlation with
aerial photography and provided site plans. Slope profiles were measured using a handheld laser range finder
to a relative accuracy of ±0.2m.
Fieldwork was undertaken on 17 May 2019. The weather at the time of the investigation was cloudy with
scattered showers.
Drone mapping was processed using specialist photogrammetry software to produce an ortho-rectified aerial
photograph Site contours were derived from LiDAR data and cadastral boundaries were retrieved from the
Queensland Spatial Catalogue.
Site plans showing the position of investigations, key site features and the proposed development, along with
borehole logs, test results and geological section is given in Appendix 1. Photographic plates showing the site
and specific features are given in Appendix 2.
1.4 Qualifications of the Responsible Person
The fieldwork and this report have been prepared by Michael Grinceri, a Principal Geotechnical Engineer, with
over 16 years of professional experience as a geotechnical engineer and engineering geologist with significant
experience and expertise with engineering description of soil and rock materials, geomorphology and landslide
mapping, landslide risk assessment and remedial design on landslide sites throughout Queensland. He is a
qualified geologist and civil engineer, member of Engineers Australia, a chartered professional engineer and
registered engineer in Queensland (RPEQ #13820).
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2. DESKTOP STUDY AND DESCRIPTION OF SITE CONDITIONS
2.1 Regional Geology
The regional geology of most of the site comprises the Early to Mid Triassic Age Kin Kin Beds which comprises
arenite, argillite and phyllite. Part of the north-western corner of the site comprises Tertiary Age Basalt which
comprises mostly olivine basalt flows and some plugs; some areas of nephelinite, basanite etc. (QLD 2011)
It is noted that the basaltic material tend to be located along the ridge tops and generally comprise red clay
with boulders of basaltic rock. This material is underlain by weathered Kin Kin Beds.
2.2 Investigations by Others
Drilling for the site classification and effluent disposal was undertaken by Global Testing, but the results of this
drilling was not available at the time of writing.
2.3 Site History
A summary of the site history was gleaned from public domain aerial photography and GIS data of the site
sourced from Google Earth, QImagery data, Queensland Globe and Noosa Shire Council online mapping
application. There are a number of photographs of the site of various quality and resolution dating back to
October 1953. The following is a summary of the development of the site:
• In October 1953 about 75% of the site was cleared of trees and converted to grass land with minor
areas of cropping. There were some buildings in the middle west of the site with an access road
following the creek back to Upper Pinbarren Creek Road;
• By January 1958 over 90% of the vegetation had been cleared from the site, with remnant vegetation
confined to ridges and the upper parts of southward facing slopes;;
• By December 1967, it appears that some of the vegetation had started to grow back;
• By January 1974, the remaining vegetation along the ridges and upper slopes had been cleared but
thick vegetation was growing around the creeks. A small track was present at the location of Ewarts
Road, but the main access was along the track about halfway down the site. Buildings are present
near the main creek;
• By January 1979, the buildings had been removed from the property and the main access track
appears to have been abandoned. Some of the vegetation around the creeks have been cleared and
scattered trees are growing on the slopes. The eastern boundary of the site is clear due to
differences in clearing and grass growth;
• In August 1984 a track had been pushed along the main creek to the position of the current
residence, with buildings at this location. It appears that the cut and fill pad at this location was
constructed at this time;
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• In September 1989 Ewarts Road had been formed along with the driveway from Ewarts Road to the
current residence, the original access along the creek also appeared to be operational. The slope of
the proposed house was completely clear of vegetation;
• By August 1993 the access road along the creek had disappeared between the boundary of the site
and Upper Pinbarren Creek Road, although the section within the property appeared to still be used;
• Vegetation on the slope around the proposed house did not appear until mid-2001, by this time
vegetation growth on the remainder of the site had grown to about 75% coverage;
• Between 2007 and 2011, the slope on the cut to the current residence suffered a minor slumping
failure;
• By 2008 one of the buildings near the creek had been expanded and appears to be used as a
residence, but this had ceased by mid-2012;
• By mid-2015 additional structures had appeared around the current residence;
• Between 2015 and the time of the investigation there did not appear to be any changes to the site.
2.4 Subsurface Conditions
The subsurface conditions on the site were found to comprise the following:
• Topsoil – Generally 50mm to 100mm thick, comprised pale brown to brown low plasticity clay. The
soil showed evidence of biological activity but seemed to lack any significant organic content;
• Colluvium – This material comprised clay with gravel and gravelly clay. Gravel comprised platy
fragments of weathered phyllite. This material was about 0.15m thick in HA1 and became thicker
down the slope to 0.8m thick in HA3. Note that HA3 had a layer of phyllite within the colluvium
material, this was interpreted as being a boulder deposited within the original material, but which has
subsequently weathered in-situ;
• Residual soil – Comprises low plasticity clay with gravel to clayey gravel. The material had relic
foliation structures and abundant sericite. Gravelly material comprised pieces and thin layers of
phyllite with clay seams between, it appears that the contacts of this material may be gradational;
• Weathered rock – the weathered rock comprises extremely to highly weathered phyllite. The
strength was somewhat variable in thin layers between very low to moderate strength. The material
is distinctly foliated and breaks down to platy material on excavation.
It is noted that although the excavated phyllite part easily and crumble when worked by hand the in-situ
material does not behave in this manner. It is expected that the weathered phyllite can be excavated using
normal machinery for the cut and foundations. It should be noted that the excavated material will be
problematic to compact and if not compacted correctly will be prone to erosion and slumping.
The geological section in Appendix 1 gives the interpretation of the relative position of these geological units
on the site.
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2.5 Topography
The topography of the site comprises:
• The site comprises a series of mainly east-west oriented hills that are up to 160m above the toe;
• Creeks through the site form a dendritic pattern;
• The base of the valleys comprises a flatter area comprising flood plain deposits;
• The creek meanders across the valley floor, based on historical aerial photographs it appears that the
course of the creek has changed over the last 70 years with meanders becoming cut off;
• The gradient of the hill sides vary between 40% and 80% with isolated areas graded at >100%;
• The valley floors grade at between 0% and 25%;
• The area where the house is proposed generally grades at about 20% to 35% towards the south, with
an area with a gradient of <10% near the road and grading at between 45% and 60% to the south-east
and south-west with a ridge between.
Key details of the site topography are shown on the site plans in Appendix 1. Drawings DWG-01 and DWG-02
show the contours of the site in general and of the proposed house location, DWG-03 shows the gradients of
the slope in the vicinity of the proposed house.
2.6 Groundwater
No groundwater was encountered on the site during the investigation.
However, based on the geology and site conditions it is expected that an intermittent perched groundwater
table would develop in superficial soils following periods of extended rainfall.
A large clump of bracken ferns was noted on the site between HA1 and HA2, these are generally associated
with intermittent seepage. Drilling was located both above and below this featured but no groundwater way
observed, and the lower part of the soil profile was largely dry. It is possible that these ferns are present due
to shallow seepage of water from the roadside drainage into the slope.
Note that these groundwater observations are made on the condition of the site at the time of the
investigation. Groundwater conditions on the site may be affected by short and long-term weather cycles,
climate change and surrounding development. Where possible, tell-tale signs, geological conditions or
regional geology that may contribute to groundwater seepage will be identified during the investigation.
However, the specific performance of seepage or groundwater may not be able to be fully defined during the
duration of the investigation. Consequently, changes to groundwater conditions, including but not limited to
ceasing, new or increased groundwater seepage, may affect the property in the future.
2.7 Surface Drainage
The surface drainage of the site comprises:
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• In general, the site drains through a catchment of a creek that drains to the east, the general pattern
of drainage is dendritic;
• Near the proposed house, surface drainage is via overland flow to the creeks located to the south-
east and south-west.
Key site drainage features are shown on the site plans in Appendix 1.
2.8 Vegetation
The vegetation present on the site comprises:
• The site comprises a combination of regrowth trees, some regrowth undergrowth, introduced trees
and weeds, trees appear to reach a maximum height of 30m to 35m;
• Around the proposed house the site is mainly clumpy long grass with shorter grass underlay with
various weeds;
• A clump of bracken ferns occurs between HA1 and HA2 on the slope, this appears to form a contour
along the slope, there are some scattered ferns for about 10m below this patch;
• The gullies on either side of the proposed house comprise pioneer tree species with predominantly
lantana under growth;
• There is a stand of a tall grass to a height of about 2.5m adjacent to the roadway.
Key details of the site vegetation are shown on the site plan in Appendix 1.
2.9 Buildings and Other Structures
The following is a description of the number, type and condition of buildings or other structures currently
present on the site:
• There are a couple of scattered farm buildings near the main creek ;
• An existing residence constructed from a transportable building with some sheds and water tanks are
located on a cut/fill platform down slope from the proposed house;
• An existing driveway constructed using cut/fill methods is located from Ewarts Road to the existing
dwelling.
The position of key buildings or other structures are shown on the site plans in Appendix 1.
2.10 Other Observations
The following site observations are relevant to the investigation:
• It is noted that cleared gullies on properties surrounding the site had tension cracks and hummocky
ground associated with landslip features. Some of these features are identified on DWG-01 and in
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the photographic plates. A review of historical aerial photographs show that these features have
become progressively worse with time;
• It is apparent that the proposed house site was used for grazing cattle due to the fresh cow pats;
• It appears that all the original vegetation has been cleared from the site at one time or another over
the last 70 years, the presence of pioneer tree species is indicative that the regrowth bushland hasn’t
yet reached maturity.
The position and/or extent of other relevant observations are shown on the site plan in Appendix 1.
2.11 General Comments
Based on professional experience the following general comments are made about the site and/or works
completed to date:
• It appears that the soil material contained within the gullies is both thicker and more prone to
instability, the presence of trees in these areas appear to provide some stability to the material, but
that care should be taken to avoid exasperating problems in these areas.
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3. ASSESSMENT OF LAND STABILITY
3.1 Existing Conditions
An assessment was made for tell-tale signs of slope instability over the site; the features identified comprised
the following:
• Colluvial soil as a mantle on the slope;
• Tension cracking and creek instability in gullies on surrounding slopes;
• Shallow slumping in cut batter slope.
The impact of observed instability and other slope factors is discussed further in Sections 3.2 and 3.4.
3.2 Components of Development and Potential Geotechnical Impact
The proposed development is likely to have a geotechnical impact on the site, the manner and extent of this
impact is dependent on the location and manner of the component of development. A summary of potential
geotechnical impacts of various components of the development and the potential instability mechanisms is
summarised in Table 1.
Table 1 - Development components with geotechnical impact and potential instability mechanism
Development Component Potential Geotechnical Impact Potential Instability Mechanism
Construction of house Loading of the slope Global instability
Steepening of slope, exposure of
Cut batters Wedge failure, translational slide
internal rock defects
Global instability, shallow
Fill batters Loading of the slopes
slumping
Wastewater irrigation area and Saturation of steeper sections of Creep flow and translational
stormwater disposal the slope sliding
3.3 Slope Stability Risk Assessment
The slope stability assessment was completed using the requirements if the Australian Geomechanics Society
“Practice Note Guidelines for Landslide Risk Management 2007” (Walker et al 2007). This framework provides
the requirements for assessments and the allocation of risk to landslide prone and steep land areas.
The site has been identified by the council as being in either a steep land and/or landslide prone area and
consequently the impact of the proposed development on the stability of the site needs to be considered.
The potential hazards identified in section 3.2 or that would need to be considered for this type of
development would comprise the following:
• Global failure – complete failure of the slope and the building;
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• Wedge failure – failure of rock along two or more natural defects such as foliation and/or joints;
• Shallow slumping – shallow rotational failure in soil and soil like materials;
• Translational sliding – sliding of soil materials over shallow underlying rock;
• Creep flow – slow movement of soil over underlying materials, these slips can exhibit features of both
shallow slumping and translational sliding.
Table 2 outlines the risk assessment for the various mechanisms given above:
Table 2 - Slope risk assessment for various mechanisms
Potential Assessed
Likelihood Consequence Comments
Hazard Risk
A likelihood of RARE has been adopted for the site
since there is no evidence of major slope failures in
the surrounding landscape. The likely consequence
Global failure RARE MAJOR LOW of a failure would result in significant damage to the
proposed structure. Therefore, the assessed risk is
LOW.
A likelihood of POSSIBLE has been adopted for the
site since there are proposed cuts into rock and this
manner of failure is common within the Kin Kin Beds
Wedge failure POSSIBLE MINOR MODERATE elsewhere. The likely consequence of a failure would
result in minor damage to the cut batter slope that
would require the removal of spoil. Therefore, the
assessed risk is MODERATE
A likelihood of LIKELY has been adopted for the site
since fill material will comprise soil with sericite and
Shallow
slumping
LIKELY MINOR MODERATE crushed phyllite material. The likely consequence of
a failure would result in partial loss of fill batter
slopes. Therefore, the assessed risk is MODERATE
A likelihood of UNLIKELY has been adopted for the
site since the cut batter slope will be occurring at the
Translational upper, flatter sections of the site. The likely
sliding
UNLIKELY MINOR LOW consequence of a failure would result in minor
deposition of material onto the cut platform.
Therefore, the assessed risk is LOW
A likelihood of LIKELY has been adopted for the site
since the mechanism is present in multiple locations
on surrounding slopes. The likely consequence of a
Creep flow LIKELY MEDIUM HIGH failure would result in damage to part of the site
which may require stabilisation works. Therefore,
the assessed risk is HIGH
Further information on landslides and the risk assessment process can be found in Australian Geoguides LR1,
LR2, LR3, LR4 and LR7.
3.4 Slope Risk Mitigation
The sections below give recommendations to reduce the risk associated with the hazards identified above.
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3.4.1 Wedg e Failure
Wedge failure occurs when a block of rock falls from a batter slope due to two or more intersecting planes of
weakness daylighting on the slope face. The Kin Kin Beds have distinct foliation that results in the excavated
material parting easily along the foliation planes and there are known tectonically formed joint planes. Note
that this style of failure may not be able to be stopped, the risk will increase with time as this material will
degrade in the cut with time, but the likelihood and impact can be reduced through the following means:
• The material is to be cut no steeper than 1(V):1(H), if the foliation is parallel or sub parallel to the face
and at a shallower angle than 45°, then the slope should be cut back to the foliation angle;
• Care should be taken to ensure that water in not allowed to flow over the batter slope and that water
is not allowed to pond on the slope above the cut;
• Periodic inspection and removal of wedges as they start to occur is prudent;
• It may also be prudent to cover the slope with a non-woven geotextile (MRTS27 Class B or greater) or
a semi-rigid finish like Concrete Canvas. It is not recommended to cover the slope with finishes that
would prevent water draining from the slope (ie grout or sprayed concrete).
The mitigation method will reduce the consequence of the event to INSIGNIFICANT, meaning that the
assessed risk will be VERY LOW.
3.4.2 Shallow Sl umpi ng
The shallow slumping is more likely with fill materials from crushed phyllite and containing sericite due to the
particle shapes causing issues with compaction resulting in lower strength soil. The following mitigation
methods will overcome the likelihood of shallow slumping from occurring:
• The water tanks are to be constructed on cut platforms with rock material across the entire base. The
tanks should be bedded onto a free draining sand layer and the overflows connected to the
stormwater management system;
• Where fill will be placed, to soil must be stripped and the slope cut into a series of 0.3m high steps to
key the fill into the slope. Requirements contained in sections 4.4 and 4.4for compaction and over
construction are mandatory for fill materials on this site. It is recommended that fill materials be
compacted using a vibrating plate compactor with a minimum mass of 250kg in loose layers not
exceeding 200mm thick;
• The top of fill platforms should be graded so that they are free draining and water should not be
allowed to pond on the fill platforms;
• Fill batter slopes shall be protected from turbulent or concentrated water flow.
Note that due to the natural grade of the slope, the fill batter slopes will need to be finished about 1(V):1.5(H)
to avoid fills with high apparent heights.
The mitigation method will reduce the likelihood of the event to UNLIKELY and will reduce the consequence
of the event to INSIGNIFICANT, meaning that the assessed risk will be VERY LOW.
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3.4.3 Creep Flow
Based on a review of the surrounding slopes it appears that the soil in the gullies is prone to creep failure.
Generally, this type of failure occurs in thick soil on steep slopes and when the material is saturated. Creep
failures may undergo slow movement with the development of tension cracking and hummocky ground for
several years. Eventually, the failure will reach a critical point where the rate of movement will increase
resulting a large scale rotational or translational failure.
Prevention of creep flow type failures is considerably easier than trying to remediate them once they have
started to move. The following will reduce the risk of the development of creep failures:
• Place the wastewater irrigation area and stormwater discharge on a ridge or within the upper half of
the slope to the gully;
• Generally, avoid slopes with a gradient of >45%;
• Ensure that the collection and disposal of stormwater flows is designed using the recommendations
contained in section 4.5;
• Ensure that stormwater and tank overflows are discharged via a dissipater structure that will slow and
spread the flow. Avoid concentrated or point discharges onto the slope;
• Ensure that areas down slope of wastewater irrigation and stormwater discharge are vegetated using
plants with fine fibrous roots and that encourage the growth of ground cover;
• Ensure that the lower 25% of the slope into the thalweg of the gully has groundcover vegetation with
fine roots and trees.
The mitigation method will reduce the likelihood of the event to UNLIKELY and will reduce the consequence
of the event to MINOR, meaning that the assessed risk will be LOW.
3.5 Geotechnical Constraints to Development
Geotechnical conditions on the site mean that the following constraints will apply to the proposed
development to prevent or limit the likelihood of the development resulting in the development of new or re-
activation of existing instability on the site. These constraints comprise:
• Placement of wastewater irrigation area – wastewater irrigation area not to be installed on a slope
with a gradient >45% or less than 50% of the way down the slope between the thalweg and ridge line;
• Placement of stormwater discharge – stormwater discharge point not to be installed on a slope with a
gradient >45% or less than 50% of the way down the slope between the thalweg and ridge line.
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4. RECOMMENDATIONS FOR DEVELOPMENT OF SITE
4.1 Site Preparation
The following recommendations are made for preparing the site for construction:
• Topsoil should be stripped from all areas where foundations and slabs will be constructed;
• Grass, shrubs and small trees should be cleared from the site, including large clumps of roots;
• Trees should be cleared with stumps and large roots grubbed from the site; holes created by grubbing
should be filled with Select Fill in accordance with Section 4.3;
• Sections of the site where foundations and slabs on grade are to be constructed should be proof
rolled to identify low strength materials;
• Where low strength materials are identified, they should be excavated and replaced with Select Fill in
accordance with Section 4.3.
Stripped topsoil may be used to rehabilitate fill batter slopes.
Where large trees, clumps of trees, old buildings, swimming pools, ponds, effluent disposal systems or other
significant moisture source is being changed prior to construction, then the site may be subject to abnormal
moisture conditions. Abnormal moisture conditions could be detrimental to the slope stability of the site.
Further guidance on site preparation can be found in Australian Geoguide LR5 Water and Drainage and LR8
Hillside Construction.
4.2 Foundation Design and Construction
Based on the results of the site investigation and risk assessment it is recommended that the foundations
should comprise punch pad pole foundations or strip foundations using the foundation design parameters
given in Table 3.
Table 3 - Foundation design parameters
Founding Layer Allowable
Foundation Type Comments
Name Capacity
Base of foundation to be not less
Pole base Weathered rock 175kPa
than 1 diameter into intact LS rock
Foundation to be proof compacted
and any wet, soft or heaving ground
Strip foundations Weathered rock 100kPa
excavated and replaced with
compacted Select Fill
When designing foundations care should be taken to ensure that future temporary or permanent excavations
do not damage the foundations. Guidance for design of foundations under these conditions can be found in
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AS2870 – 2011 Sections 6.2 and 6.3. Design for effect of trees in close proximity to foundations should
following the requirements of AS2870 – 2011 Appendix H.
The base of all foundations should be cleared of all loose or remoulded soil. It is recommended that all
shallow footing excavations be proof compacted using a 300mm vibrating plate compactor to ensure sufficient
density and reduce the effect of construction settlement. Foundation excavations should be protected from
the infiltration of water that may result in the swelling or softening of soil and weathered rock. Foundations
should be inspected by a registered geotechnical engineer prior to the placement of concrete to ensure that
they meet the requirements of this report and the foundation design.
Further guidance for construction on landslide prone sites is contained in Australian Geoguide LR8 Hillside
Construction.
4.3 Earthworks Recommendations
Where fill materials are required to change site levels or fill holes formed during site preparation, then Select
Fill should be used, which meets the following requirements:
• Well graded granular material, may be site sourced, imported or recycled;
• Less than 15% finer than 75µm, fines should be low to non-plastic;
• Less than 10% greater than 20mm, no material larger than 75mm;
• Free from contamination such as salt, hydrocarbons, chemicals, timber, palm fronds, cement fibre
sheeting and pipes, collapsing soils, sensitive soils, untreated acid sulphate soils, soils that contain
materials that are water soluble, asbestos or domestic, industrial, mine and/or building waste;
• Generally less than 5% inert waste, including plastic, bricks, concrete, small metal fragments or road
building products (exceptions may apply to recycled materials);
• Less than 5% finely divided organic matter and no clumps of organic matter. Finely divided organic
matter includes treated acid sulphate soils, small leaves, mulch, dispersed dried grass and roots to
5mm;
• Generally, avoid rock that crushes or degrades during handling and compaction, or forms fragments
that are elongated or platy, ie shale, siltstone, claystone, mudstone, some phyllites, slates and schists.
It is noted that site won fill will comprise phyllite. When phyllite is used as fill the rock particles tend to form
platy particles that are difficult to compact properly, and the rock material will tend to break down on
handling. It is imperative that this material be properly compacted to ensure that the fill platforms are fit for
purpose.
Fill material should be placed in a controlled manner to meet the requirements of AS3798 – 2007. All fill
materials should be placed in loose layers not exceeding 200mm thick, moistened and compacted using a
vibrating plate or roller to 95% SMDD. Smaller or light compaction equipment may require thinner layers to
ensure compaction through the full depth of the layer. Compaction using site machinery, flooding or static
rollers generally does not meet these requirements. Other fill materials may be used, but could have an
adverse effect on the site classification or slope performance.
LEONTAKIANAKOS-R-001 Page 13 26 May 2019
Page 17
TRUBUILT
SLOPE RISK ASSESSMENT REPORT
Further guidance on earthworks is contained in Australian Geoguide LR8 Hillside Construction.
4.4 Batter Slopes for Cut and Fill
The proposed development includes the requirements to modify levels on the site through earthworks. Note
the performance of slopes is dependent on materials, type of material, slope angle, loading and can change
with time. The following recommendations are made with respect to retaining walls, and/or batter slopes in
cut or fill:
• Fill slopes should be constructed using compacted material that is initially over constructed and the
cut back to the final position, fill slopes should generally be no steeper than 1(V):1.5(H), fill slopes
greater than 5m in total height should be benched to reduce the overall slope length. Modifications
to this recommended batter angle may be approved following inspection and/or design by a suitably
qualified geotechnical engineer;
• Cut slopes in soil should generally be no steeper than 1(V):1.5(H) and slopes greater than 5m in total
height should be benched to reduce the overall slope length. Modifications to this recommended
batter angle may be approved following inspection and/or design by a suitably qualified geotechnical
engineer;
• Cut slopes in weathered and decomposed rock should generally be no steeper than 1(V):1 (H) and
slopes greater than 4m in total height should be benched. Note that if the foliation of the rock is sub
parallel to the slope, the rock should be cut to the prevailing foliation angle for greater stability.
Modifications to this recommended batter angle may be approved following inspection and/or design
by a suitably qualified geotechnical engineer;
• Unless crest drainage will be maintained or comprise self-flushing, trowelled concrete lined drains
then it is recommended that other methods for the control of surface water on slopes be utilised;
• Examples of suitable crest and slope drainage would include grass lined drains that are regularly
mowed with the surrounding grass, drains lined with Concrete Canvas™, trowelled concrete, stone
pitching or wire mattress revetments, paving, concrete or steel drainage channels, or some specialist
geotextile products. Note that it is recommended that drain liners protect the underlying soil from
erosion and include stilling or dissipating features to slow the velocity of flow along and at the outfall
location. The use of timber or natural fibres (hemp, cotton, jute or coir) is not recommended for
permanent drainage features,
• Where crest and slope drainage are formed from fill materials, fill materials should use non-dispersive
soil that is compacted and formed to a suitable batter slope. Drains formed from cut/fill soil should
have battered sides, be appropriately lined and be of suitable size with regards to the catchment area
and characteristics, design storm, method of lining, maintenance and/or effect if the drain overflows;
• The cut and fill batter slopes in soil and weathered or decomposed rock should be protected from the
effects of surface water flow through planting with grass, groundcover, shrubs and small trees.
Generally, plants should have fibrous root and allow undergrowth. Large trees with shallow root
systems, conifers and plants that prevent the development of undergrowth should be avoided;
• Trees and other plants with invasive root systems should not be allowed to grow on cut slopes in rock
as they can result in root wedging and degradation of the slope;
LEONTAKIANAKOS-R-001 Page 14 26 May 2019
Page 18
TRUBUILT
SLOPE RISK ASSESSMENT REPORT
• Slope coverings such as jute mat, non-woven geotextiles or woven weed mats provide only
temporary protection to slopes and should not be relied upon for long term protection of batter
faces. For further information about the applicability of these methods seek advice from a suitably
experience geotechnical professional;
• Often the most effective protection to cut slopes is afforded through the growth of weeds on the
slope. When weeds need to be controlled or removed they should be slashed or poisoned. Weeds
should never be torn out of slopes as this generally results in rapid degradation of the slope.
Further guidance on the maintenance of retaining walls, and cut and fill slopes is found in Australian
Geoguides LR6 Retaining Walls and LR8 Hillside Construction.
4.5 Surface Drainage Recommendations
Management of surface and groundwater flows is essential to ensuring ongoing slope stability and foundation
performance. The following recommendations are made for the configuration and maintenance of site
drainage:
• It is recommended that the soil be graded to fall not less than 50mm for the first metre from the
structure with a low permeability soil;
• Site drainage requirements should form a planned part of the site landscaping and may need to
modified or changed depending on the performance of the drainage in peak rainfall events. Site
drainage should be inspected regularly and maintained as required to keep it serviceable;
• The site stormwater system should also account for incidental sources of water including tank
overflows, surface flows from paved and driveway areas, and minor drains;
• Stormwater should be directed away from the structure to a suitable outlet structure that will slow
and spread the flow onto the slope. The stormwater outfall should never be discharged onto bare
natural or fill soils.
Further recommendations for surface drainage can be found in the Australian Geoguides LR5 Water &
Drainage and LR9 Effluent and Surface Water Disposal.
4.6 Recommendations for Wastewater Disposal
An investigation and assessment for the most appropriate method of wastewater and effluent treatment and
disposal has been prepared by Global Testing and is presented in their report.
The following recommendations are made with respect to the siting and construction of wastewater disposal
infrastructure:
• It is recommended that wastewater irrigation areas be planted with species that will promote
undergrowth and/or have fibrous roots that aid in binding of the soil to prevent erosion;
LEONTAKIANAKOS-R-001 Page 15 26 May 2019
Page 19
TRUBUILT
SLOPE RISK ASSESSMENT REPORT
• Requirements to mitigate the effect of the wastewater disposal on slope stability issues are contained
in sections 3.4.3 and 3.5.
Further information and guidance regarding siting and construction of wastewater disposal systems on
landslide prone sites can be found in Australian Geoguide LR9 Effluent and Surface Water Disposal.
4.7 Long Term Maintenance Requirements
Under Australian, Queensland and local government building regulations home owners have obligations for
maintaining the integrity of constructions on residential property. Further details of these obligations relating
to site classification, foundation performance and maintenance is given in the QBCC Guide “A Simple How-to
Guide to Preventing Structural Damage” and in CSIRO BTF-18 “Foundation Maintenance and Footing
Performance: A Homeowner’s Guide”. The Australia Geomechanics Society produce a selection of brochures,
called the Australian Geoguides, that provide further details on the slope risk assessment process and make
recommendations for good hillslope construction practice. Copies of these brochures can be provided on
request.
This investigation has been undertaken by an experienced professional geotechnical engineer who through a
combination of site observations, limit historical data and experience with similar construction methods or
geology. Regardless, the investigation is based on a very short observation compared to the design life of the
structure; time, changing weather and/or climatic conditions, surrounding development or earthworks,
modification to vegetation on or off the site, landscaping and other factors may change the impact of the
observed hazards or introduce new hazards that were not identified during the investigation. To reduce the
effect of these changes to the proposed development home owners should follow the requirements given
within this report and within the brochures stated above.
During this investigation we found the following geotechnical conditions that may affect the long-term
performance of the property:
• Cut batter slopes are expected to degrade over the life of the structure, minor slips should be cleared
away as required;
• If the stormwater management system is not maintained, then slope failures will likely occur;
• If fill batter slopes are not protected or remain vegetated, then erosion of these slopes is likely to
occur.
Recommendations for management of these identified long term risks are given in Sections 3 and 4 of this
report. Failure to landscape and maintain the property to the requirements of this report and the brochures
above may result in an adverse outcome for the development.
LEONTAKIANAKOS-R-001 Page 16 26 May 2019
Page 20
TRUBUILT SLOPE RISK ASSESSMENT REPORT 5. REFERENCES AS1726 – 2017 Geotechnical Site Investigations. Standards Australia, Canberra. AS2870 – 2011 Residential Slabs and Footings. Standards Australia, Canberra. AS3798 – 2007 Guidelines on Earthworks for Commercial and Residential Developments. Standards Australia, Canberra. AS4055 – 2012 Wind Loads for Housing. Standards Australia, Canberra. Fox, E. 2002. Development of a map of Thornthwaite moisture index isopleths for Queensland. Australian Geomechanics Journal, June 2002. QLDG 2011 Geological GIS data set based on 100k geological mapping. Based on or contains data provided by the State of Queensland (Department of Employment, Economic Development and Innovation), December 2011. QLD 2014. Queensland Globe GIS data set overlay for Google Earth. Based on or contains data provided by the State of Queensland (Department of Natural Resources and Mines). Noosa Shire Council Planning Scheme overlay maps Walker, B, Davies, W, Wilson, G. 2007. Practice note guidelines for landslide risk management 2007. Australian Geomechanics Society Landslide Taskforce, Landslide Practice Note Working Group. Published in Australian Geomechanics Journal, Vol 42, No 1. Willmott, W. 2007 Rocks and Landscapes of the Sunshine Coast, 2nd Ed. Geological Society of Australia, Queensland Division. LEONTAKIANAKOS-R-001 Page 17 26 May 2019
Page 21
TRUBUILT
SLOPE RISK ASSESSMENT REPORT
6. IMPORTANT INFORMATION ON INTERPRETATION, USE AND LIABILITY
OF THIS REPORT
This report has been prepared in accordance with a specific brief and scope of work. It should be read in its
entirety.
The responsibility of GA Geotechnical is solely to Trubuilt. This report is not intended for, and should not be
relied upon, by any third party. No liability is undertaken to any third party.
Ground conditions are subject to continuing natural and man-made processes. It can exhibit a variety of
properties that vary from place to place, and can change with time.
Site investigation involves gathering and assimilating data by means such as inspection, drilling, excavation,
probing, sampling and testing. The collected data is only directly relevant to the ground at the place where
and the time when the investigation was performed.
Any interpretation or recommendation given in this report shall be understood to be based on judgement and
experience, not on greater knowledge of facts other than those reported.
If different ground or site conditions are encountered during construction activities or subsequent to the
investigation performed for this report, either due to natural variability of subsurface conditions or previous
construction activities, GA Geotechnical should be notified of the differences and provided with an
opportunity to review the recommendations contained in this report.
LEONTAKIANAKOS-R-001 Page 18 26 May 2019
Page 22
TRUBUILT SLOPE RISK ASSESSMENT REPORT Appendix 1– Site Plan, Borehole Logs and Geological Sections LEONTAKIANAKOS-R-001 Appendix 26-May-19
Page 23
25
275
0
20 25
0
200
0 225
22
5
22
484250 200
5
225
25 25
0 0
250
200
22
150
200
5
17
225
17
22
20
20
5
5
5
225
0
0
20
0
22
275
20
5
225 0
200
150
200
484500
17
250 175
5
175
25
175
0
17
20
200
5
0
20
150
Eas ng (m GDA)
0
150
225
150
200
200
17
225 5
200
175
200
250
225
17
200
5
17
5
200 17
AREA COVERED BY DWG-02
17
15
5
484750 200
5
0
150
175
LANDSLIP FEATURES IDENTIFIED
225
200
DURING INVESTIGATION
200
200
175
15
15
175
0
0
15
0
200
175
175 17 17
5 5
150
485000
150
150
175
150
15
0
17
12
5
15
12
150
5
175
5
0
15
0
7089500 7089750 7090000 7090250 7090500 7090750 7091000
Northing (m GDA)
BASE IMAGERY FROM QLD GLOBE
CONTOURS AND WATER COURSES FROM QLD SPATIAL CATALOGUE
Date Rev Comments Appvd Project Title Drawing Title
DESIGN BY MG
DRAWN BY MG
TRUBUILT BLOCK OVERVIEW
SLOPE RISK ASSESSMENT REPORT PO Box 1455
NOOSAVILLE Qld 4566
APPROVED BY MG
91 EWARTS ROAD, COORAN
Ph: 0417 982 768 SCALE 1:5000
[email protected] Job Number Drawing Number Drawing Date Rev
PAGE SIZE A3 GAG16011 LEONTAKIANAKOS-DWG-01 22 MAY 19 REV A
[OCR of page images]
(va5 Ww) 3uyseq
7089500 7089750 7090000 7090250 7090500 7090750 7091000
Northing (m GDA)
Rev [Comments [Appvd Project Title Drawing Title
GA Geotechnical DESIGN BY
DRAWN BY
TRUBUILT
BASE IMAGERY FROM QLD GLOBE
CONTOURS AND WATER COURSES FROM QLD SPATIAL CATALOGUE
BLOCK OVERVIEW
SLOPE RISK ASSESSMENT REPORT | PO82% 1485 9 APPROVED BY
91 EWARTS ROAD, COORAN
Ph: 0417 982 768 [email protected] b Number Drawing Number [Drawing Date Rev
po PAGE SIZE GAGI6011 _ LHONTAKIANAKOS-OW-p122 MAY 19 [REV A
Page 24
PROPOSED DRIVEWAY 200 19
195 0
19
5
19
5
SECTION
200
APPROXIMATE POSITION OF OVERHEAD POWER LINES
7090875
19
200
0
DRIVEWAY TO EXISTING RESIDENCE
19
HA1
5
18
5
5
19
200
0
19
19
0
Northing (m GDA)
7090850
18 HA2 PROPOSED DRIVEWAY
0
5
17
195
195
18
5
190
19 HA3 18
5
0
170
18
17
0
5
7090825
190 PROPOSED HOUSE
18
5
18 180
5
0
18 175
17 18
16
0 17 185
5
0
5
7090800
484925 484950 484975 485000 485025 485050 485075
Easting (m GDA)
Date Rev Comments Appvd Project Title Drawing Title
DESIGN BY MG
DRAWN BY MG
TRUBUILT SITE PLAN
SLOPE RISK ASSESSMENT REPORT PO Box 1455
NOOSAVILLE Qld 4566
APPROVED BY MG
91 EWARTS ROAD, COORAN
Ph: 0417 982 768 SCALE 1:500
[email protected] Job Number Drawing Number Drawing Date Rev
PAGE SIZE A3 GAG16011 LEONTAKIANAKOS-DWG-02 22 MAY 19 REV A
Page 25
7090875
0.7
0.6
GRADIENT (RATIO V/H)
0.5
Northing (m GDA)
7090850
0.4
0.3
0.2
7090825
0.1
0
7090800
484925 484950 484975 485000 485025 485050 485075
Easting (m GDA)
BASE IMAGERY BY GA GEOTECHNICAL, CAPTURED 17 MAY 19
WATER COURSES FROM QLD SPATIAL CATALOGUE
GRADIENTS DERIVED FROM 1m CONTOURS FROM QLD SPATIAL CATALOGUE
Date Rev Comments Appvd Project Title Drawing Title
DESIGN BY MG
DRAWN BY MG
TRUBUILT SLOPE GRADIENTS
SLOPE RISK ASSESSMENT REPORT PO Box 1455
NOOSAVILLE Qld 4566
APPROVED BY MG
91 EWARTS ROAD, COORAN
Ph: 0417 982 768 SCALE 1:500
[email protected] Job Number Drawing Number Drawing Date Rev
PAGE SIZE A3 GAG16011 LEONTAKIANAKOS-DWG-03 22 MAY 19 REV A
Page 26
POINTID: HA1
BOREHOLE LOG
SHEET: 1 of 1
CLIENT: Trubuilt DATE COMMENCED: 17-May-19
PROJECT: Slope Risk Assessment Report DATE COMPLETED: 17-May-19
LOCATION: 91 Ewarts Road, Cooran LOGGED BY: M Grinceri
JOB NUMBER: GAG16011 - LEONTAKIANAKOS CHECKED BY: M Grinceri
CONTRACTOR: GA Geotechnical HOLE SIZE: 62mm EASTING: 485,016.700 m E COLLAR RL: 200.7 m
DRILL MODEL: Dormer Hand Auger BEARING / INCL: 0° / 90° NORTHING: 7,090,858.800 m E DATUM / ZONE: GDA94 / 56J
CEMENTING/WEATHERING
CONSISTENCY/STRENGTH
MOISTURE CONDITION
PENETROMETER
DYNAMIC CONE
BLOWS/100mm
PENETRATION
GEOLOGICAL UNIT
GROUP SYMBOL
GROUNDWATER
GRAPHIC LOG
ELEVATION
SUPPORT
METHOD
SAMPLE
DEPTH
1 2 3 5 10 15
MATERIAL DESCRIPTION COMMENTS
0
0m TOPSOIL: CLAY: low plasticity; brown grading 0.0m - short grass and weeds at
~Wp
CL
downwards to pale brown; fissured, flocced / surface, above upper extent of
COLLUVIUM
aggregated by biological activity; trace of bracken fern clump
rootlets (est 5%); cf topsoil
F
Gravelly CLAY: low plasticity; brown to pale
<Wp
CL
200.5m brown with orange - brown to orange gravel;
fine to medium grained, poorly graded,
subangular to angular, highly weathered, low 0.25m - gradational contact
RESIDUAL
to moderate strength phyllite lithic gravel,
SOIL
M-D
MD
GC
distinct foliation (est 30% to 40%); cf
colluvium
Clayey GRAVEL: fine to coarse grained, poorly
HAND AUGER
graded, subangular to angular, platy,
extremely to highly weathered, very low to
OPEN
0.5m moderate strength phyllite lithic gravel;
0.5
orange - brown mottled white, red, pink,
yellow; low plasticity clay (est 20% to 25%),
WEATHERED ROCK
clay content decreasing with depth; cf
residual soil
XW-HW
VLS-MS
PHYLLITE: fine grained; pale red - brown
D
200m
mottled orange, yellow, pink, white; sericite
in distinct foliation; strength variable in
layers; cf Early Triassic, Kin Kin Beds 0.8m - DCP refusal
1.0m - EOH, auger just grinding
1m 1
away
199.5m
1.5m 1.5
199m
2m 2
BOREHOLE COMMENTS: LOGGING STANDARD: AS1726-2017
Borehole terminated on refusal, backfilled with cuttings, groundwater not encountered.
Page 27
POINTID: HA2
BOREHOLE LOG
SHEET: 1 of 1
CLIENT: Trubuilt DATE COMMENCED: 17-May-19
PROJECT: Slope Risk Assessment Report DATE COMPLETED: 17-May-19
LOCATION: 91 Ewarts Road, Cooran LOGGED BY: M Grinceri
JOB NUMBER: GAG16011 - LEONTAKIANAKOS CHECKED BY: M Grinceri
CONTRACTOR: GA Geotechnical HOLE SIZE: 62mm EASTING: 485,016.200 m E COLLAR RL: 197.9 m
DRILL MODEL: Dormer Hand Auger BEARING / INCL: 0° / 90° NORTHING: 7,090,845.300 m E DATUM / ZONE: GDA94 / 56J
CEMENTING/WEATHERING
CONSISTENCY/STRENGTH
MOISTURE CONDITION
PENETROMETER
DYNAMIC CONE
BLOWS/100mm
PENETRATION
GEOLOGICAL UNIT
GROUP SYMBOL
GROUNDWATER
GRAPHIC LOG
ELEVATION
SUPPORT
METHOD
SAMPLE
DEPTH
1 2 3 5 10 15
MATERIAL DESCRIPTION COMMENTS
0
0m TOPSOIL: CLAY: low plasticity; pale brown to 0.0m - short grass surrounded by
CL
brown; fissured, flocced / aggregated by weeds and clumps of longer grass
biological activity; trace of rootlets (est 5%); at surface, near lower extent of
trace of decomposed organics in upper 10mm bracken fern clump
~Wp
F-St
(est 5%); cf topsoil 0.2m - trace of medium grained,
COLLUVIUM
CLAY: low plasticity; pale brown mottled poorly graded, subangular phyllite
CL
orange, red; fissured, orange and red appear lithic gravel (est 10%)
to be relic weathered phyllite gravel; cf
colluvium
Gravelly CLAY: low plasticity; pale brown
mottled white, pink, red, orange, yellow; fine <Wp
VSt
CL
197.5m
to medium grained, poorly graded,
subangular to angular, highly weathered, low
to moderate strength phyllite lithic gravel (est
0.5m 40% to 50%); cf colluvium 0.5m - gradational contact 0.5
HAND AUGER
Clayey GRAVEL: fine to coarse grained, poorly
RESIDUAL SOIL
OPEN
graded, subangular to angular, extremely to
highly weathered, verly low to moderate
GC
strength phyllite lithic gravel; orange mottled
D
pale brown, white, pink, red, yellow; low
plasticity clay (est 30%); distinct relic
layering/foliation in material; cf residual soil
PHYLLITE: fine grained; mottled orange, red,
pink, white, pale brown, yellow; sericite in
D
distinct foliation; strength varies between
WEATHERED ROCK
197m
layers; cf Early Triassic, Kin Kin Beds 0.97m - sudden reduction in DCP
XW-HW
penetration
VLS-MS
1m 1.0m - DCP refusal 1
1.2m - EOH, auger just grinding
away
196.5m
1.5m 1.5
196m
2m 2
BOREHOLE COMMENTS: LOGGING STANDARD: AS1726-2017
Borehole terminated on refusal, backfilled with cuttings, groundwater not encountered.
Page 28
POINTID: HA3
BOREHOLE LOG
SHEET: 1 of 1
CLIENT: Trubuilt DATE COMMENCED: 17-May-19
PROJECT: Slope Risk Assessment Report DATE COMPLETED: 17-May-19
LOCATION: 91 Ewarts Road, Cooran LOGGED BY: M Grinceri
JOB NUMBER: GAG16011 - LEONTAKIANAKOS CHECKED BY: M Grinceri
CONTRACTOR: GA Geotechnical HOLE SIZE: 62mm EASTING: 485,016.500 m E COLLAR RL: 193.5 m
DRILL MODEL: Dormer Hand Auger BEARING / INCL: 0° / 90° NORTHING: 7,090,831.700 m E DATUM / ZONE: GDA94 / 56J
CEMENTING/WEATHERING
CONSISTENCY/STRENGTH
MOISTURE CONDITION
PENETROMETER
DYNAMIC CONE
BLOWS/100mm
PENETRATION
GEOLOGICAL UNIT
GROUP SYMBOL
GROUNDWATER
GRAPHIC LOG
ELEVATION
SUPPORT
METHOD
SAMPLE
DEPTH
1 2 3 5 10 15
MATERIAL DESCRIPTION COMMENTS
0
193.5m 0m TOPSOIL: CLAY: low plasticity; brown; trace of 0.0m - short grass surrounded by
CL
rootlets (est 5%); flocced / aggregated soil, weeds and clumps of longer grass
F
~Wp
possibly as a result of biological activity; cf at surface
topsoil
CLAY: low plasticity; plae brown with orange
grael particles; with some fine to medium 0.2m - becomes brown mottled
red, orange
CL
grained, poorly graded, subangular to
St
subrounded, highly weathered, low strength
<Wp
phyllite lithic gravel (est 15% to 20%); cf
colluvium
COLLUVIUM
PHYLLITE: fine grained; red - pink to red -
orange; sericite in distinct foliation; with
some interbedded clay seams (low plasticity; Position of phyllite rock at this
193m 0.5m 0.5
red to red - pink), interbeds are 5mm to position within the soil profile is
10mm thick (est 45%); cf boulder of unusual and does not fit the
profile of the lithology, it is
M-D
VLS
XW
weathered rock in colluvium
therefore assumed that we have
drilled through a boulder
contained within the colluvium
material
CLAY: low plasticity; pale red to red - orange;
relic foliation with alignment of sericite in soil;
HAND AUGER
trace of fine to medium grained, poorly
VSt
graded, subangular to angular, extremely
OPEN
weathered, very low strength phyllite lithic
192.5m 1m gravel (est 10%); cf residual soil 1
RESIDUAL SOIL
<<Wp
CL
St
PHYLLITE: fine grained; red - orange to red -
192m 1.5m pink; sericite in distinct foliation; cf Early 1.5
VLS
XW
Triassic, Kin Kin Beds
1.57m - sudden reduction in DCP
WEATHERED ROCK
penetration
PHYLLITE: fine grained; red - orange to yellow
- orange, some variability in colour by layers; 1.66m - 20 for 60mm, DCP refusal
D
sericite in distinct foliation; cf Early Triassic,
Kin Kin Beds
HW
LS
1.9m - EOH, auger just grinding
away at rock
191.5m 2m 2
BOREHOLE COMMENTS: LOGGING STANDARD: AS1726-2017
Borehole terminated on refusal, backfilled with cuttings, groundwater not encountered.
Page 29
I | | | | | | t | | | | | | | MAKOS oe | | Hee [: [OO pele ey (LEONTAKIA CO52X 40 cm x 28 cm x 2 mm. GORMACK GRAPH PAPERS ®
Page 30
TRUBUILT SLOPE RISK ASSESSMENT REPORT Appendix 2– Photographic Plates LEONTAKIANAKOS-R-001 Appendix 26-May-19
Page 31
Photographic Plates
Plate 1 – Aerial view of proposed house site, north is to left of photograph
Plate 2 – General view of proposed house site, looking east
Page 32
Plate 3 – General view of proposed house site, looking west Plate 4 – General view of proposed house site, looking north
Page 33
Plate 5 – General view of proposed house site, looking south Plate 6 – Position of cut/fill pad and existing residence on slope below proposed house
Page 34
Plate 7 – Detail of shallow slump in cut batter slope above cut/fill pad Plate 8 – General view of main creek and valley bottom, looking west
Page 35
Plate 9 – Tension cracking and creep flow within gully on adjoining site to north of proposed house
site
Plate 10 – Tension cracking and creep flows within gullies on adjoining site to north of proposed
house site. Small rotation failure in red
Page 36
Plate 11 – Tension cracking and creep flow within a gully on adjoining site to east of proposed house
site. Note that tension cracking above main creep flow is indicative in a significant increase in this
failure