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Attachment 3 - Geotechnical Report
CODE FOR DEVELOPMENT ON
STEEP OR UNSTABLE LAND – GEOTECHNICAL REPORT
LOT 21 (No.16) PINES ROAD, COOROY
CLIENT: Chris Fraser
C/- DJ Sommer Homes
58 Dixon Avenue,
MALENY QLD 4552
EBIS REFERENCE: 210417-SU-GEO
PROJECT DESCRIPTION: Proposed New Residence
DATE: 4 March 2022
PO Box 973 Buddina Q 4575 Unit 2/4 Textile Avenue Warana P (07) 5436 9199; F (07) 5436 91
9198;
98; Email: [email protected]
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Page 2
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
Table of Contents
1.0 INTRODUCTION ................................................................................................2
2.0 DESCRIPTION OF EXISTING CONDITIONS ...................................................3
3.0 ASSESSMENT OF LAND STABILITY ................................................................4
4.0 DESCRIPTION OF PROPOSED DEVELOPMENT ...........................................7
5.0 ASSESSMENT OF DEVELOPMENT IMPACTS ...............................................7
6.0 SUMMARY & CONCLUSIONS ..........................................................................8
Appendix A
Site Plan WD104 - Working Drawings, Sheet 2 of 13, dated 19.11.2021
Site Earthworks & Site Drainage Plan - A3-210417-DW1
Landslip Hazard Overlay Map, courtesy of Noosa Plan 2020
Geology Map Courtesy Queensland Globe Mapping System
Landslide Risk Management (Examples of Good Hillside Practice)
Landslide Risk Management Appendix J (Some guidelines for hillside construction)
Practice Note Guidelines for Landslide Risk Management 2007
Appendix C: Landslide Risk Assessment Qualitative Terminology for use in Assessing Risk to
Property
PROPOSED NEW RESIDENCE PAGE 1 OF 10 4 March 2022
Page 3
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
SITE INVESTIGATION – GEOTECHNICAL REPORT
1.0 INTRODUCTION
EBIS, practising as a geotechnical engineer, has carried out a site investigation at No. 21
Pines Road, Cooroy. The investigation was conducted in order to assess the conditions on
the site for the proposed development of a dwelling.
1.1 Details of Development
The proposed development consists of a single level dwelling on a concrete slab with
elevated timber framed decks to the south east side. The development will require
earthworks for access construction, cut/fill earthworks for building site preparations,
excavations of footings/foundations and installation of services. Earthworks will also be
required for site drainage works.
1.2 Site Location & Description
The site is described as Lot 21 on SP 308933 and is 3.86ha in area. It is located to the south
west of Cooroy Township on the west side of Pines Road. The allotment is locally in an area
of undulating to steep hills on Kin Kin beds. The site has frontage to Pines Road, as shown in
the aerial photograph below.
Figure 1 – Aerial Image of the Site
(Courtesy of Noosa Plan 2020)
1.3 Method & Scope of Investigations
A walkover and subsurface investigation was undertaken on 21 January 2022. A total of
three (3) boreholes and three (3) Dynamic Cone Penetrometer tests (DCP) were excavated
to refusal on weathered shalley rock. Exposed faces of cut embankments were examined in
terms of erodibility and stability. An undisturbed sample of the subgrade material was taken
and tested for shrinkage characteristics.
Following the site investigation and a site walkover by EBIS, a desk top study was
undertaken of the site and the general surrounding area.
PROPOSED NEW RESIDENCE PAGE 2 OF 10 4 March 2022
Page 4
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
1.4 Qualifications of Responsible Individual(s) &/or Company
Don Stanfield, Owner/Director of EBIS has worked as a geotechnical engineer in this region
for over 25 years and has a Bachelor of Engineering BE (Civil). Don is registered as a
professional engineer in the states of Queensland (RPEQ No.4177). Victoria (E.C.19910) and
is on the National Profession Engineers Register (NPER3).
Mr Stanfield has lived and worked on the Sunshine Coast for over 30 years and has
undertaken work throughout the South East Queensland region.
Lindsay Wheeler, our site and soil assessor is experienced in local conditions and has
worked for EBIS for over 19 years. Relevant experience includes the investigation of sites
and design and supervision of stabilisation for various sites having landslip risk.
2.0 DESCRIPTION OF EXISTING CONDITIONS
2.1 Geology (local & regional)
The geology of the site is shown on Queensland Globe Mapping System as being Rk – Kin
Kin beds.
Figure 2 Geology Map Extract
Noosa Council mapping indicates soils in this region are GRYP – Gravelly red and yellow
podzolics on Kin Kin beds.
Boreholes excavated and examination of the rock surface of the cut embankment on site
generally confirmed the above. Details of subsurface investigations are included in the
following section.
PROPOSED NEW RESIDENCE PAGE 3 OF 10 4 March 2022
Page 5
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
2.2 Soil Profiles
Site/Soil Summary:
Moderate to steep slopes of broad ridge line.
Cut and fill earthworks proposed.
Existing cut embankments present.
The natural soils generally consist of high plasticity silty clays and shalley gravelly silty clays
overlying weathered shalley gravels (weathered rock).
Slight seepage was encountered on the rod of DCP no.3 upon extraction indicating
seepage at the clay/weathered rock interface.
For full details of the site/soil conditions refer to the separate Site Classification Report
210417-SI/FD.
2.3 Site Classification
In accordance with the "Residential Slabs and Footings" code we have classified the above
site as a 'M' Class site.
The site has been classified as “M” because the soil is moderately reactive to changes in soil
moisture.
The footing design for this site must consider the following factors:
1. Cut and fill earthworks are proposed to be undertaken to provide level building
platforms
2. The site slopes moderately to steeply.
3. Existing cut embankments exist on/near the site.
4. Clays present in the soil profile are moderately reactive.
5. Rocks/rock floaters are likely to be encountered during footing excavations.
6. There needs to be drainage control of surface water.
2.4 Topography
The proposed house site is located centrally on a ridge line which slopes towards the north
east at approximately 20-25%. Cut and fill earthworks are proposed to be undertaken to
provide a level building platform.
Figure 3 Proposed House site located on broad ridge line
PROPOSED NEW RESIDENCE PAGE 4 OF 10 4 March 2022
Page 6
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
An existing unsealed track and cut embankments are to the south side of the development
area.
Figure 4 Unsealed track & cut embankment adjacent development area
2.5 Groundwater
Ground water or springs was not encountered during excavations.
There was no evidence of significant seepage or groundwater emanating from the rock
faces of the existing cut embankment.
2.6 Surface Drainage
Surface drainage is typically good due to the natural slopes.
Surface water traversing the site is minimal as the slopes or the crest of the broad ridge line
sheds water away from the site.
2.7 Vegetation
The site is well grassed. There are no trees on/near the site.
2.8 Buildings, other structures
There were no buildings or structures on the site at the time of the investigation.
3.0 ASSESSMENT OF LAND STABILITY
3.1 Existing Conditions
No evidence of recent or historic slope instability was observed across the site during the
investigation.
Trees were vertical, no irregular surfaces or landslip backscarps were noted. Weathered
rock was intersected at relatively shallow depth across the site.
Weathered rock is evident in the faces of the existing cut embankments which were
generally >1V :1H. The rock face in the cut embankments appeared to be generally sound
with no collapse or failure of the rock surface.
PROPOSED NEW RESIDENCE PAGE 5 OF 10 4 March 2022
Page 7
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
Figure 5 Weathered rock evident in face of cut embankment
Some minor areas were prone to erosion where the bedding of the weathered rock was
“dipping” down allowing the shalley gravels to come loose.
3.2 Stability Zoning
3.2.1 Risk of Slope Instability/Landslip
The Landslide Hazard overlay map (1) from Noosa Plan 2020 shows this area to be low risk
at the crest of the ridge line above the site to moderate risk across the development area.
NOTE: The council overlays are a “typical” guide to the site conditions in the location
shown in terms of steep land and landslip risk.
Table 1 - Risk Level Implications
Risk Level Example Implications (1)
VH VERY HIGH RISK Extensive detailed investigation and research, planning and
implementation of site treatment options essential to reduce risk to
acceptable levels; may be too expensive and not practical
H HIGH RISK Detailed investigation, planning and implementation of site treatment
options required to reduce risk to acceptable levels.
M MODERATE RISK Tolerable provided site treatment plan is implemented to maintain or
reduce risks. May be accepted. May require investigation and planning of
various options.
L LOW RISK Usually acceptable. The site treatment requirements and responsibility to
be defined to maintain or reduce risk.
VL VERY LOW RISK Acceptable. Manage by normal slope maintenance procedures.
Note: (1) The implications for a particular situation are to be determined by all parties to the risk assessment; these are only
given as a general guide.
Taken from the AGS Extract containing “Practice Note Guidelines for Landslide Risk
Management 2007”. It is indicated that the local government and government bodies
(councils or other authorities) as regulators have the responsibility or authority to assess
hazards eg; Landslides of potential risk to development of land that is possibly “at risk” and
ensure that the risk levels are properly considered.
If mitigation is required, Planning and Design for the development should include works
which result in acceptable risk levels to property after completion of construction. In some
cases, subject to appropriate monitoring and maintenance programs, a tolerable risk may be
accepted.
PROPOSED NEW RESIDENCE PAGE 6 OF 10 4 March 2022
Page 8
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
Definitions of acceptable and tolerable risks as included in the AGS Practice Note Guidelines
are as follows:
Tolerable Risk: risks within a range that society can live with so as to secure certain benefits.
It is a range of risk regarded as non-negligible and needing to be kept under review and
reduced further if practicable.
Acceptable Risk: risk which everyone affected is prepared to accept. Action to further
reduce such risk is usually not required unless reasonably practicable measures are available
at low cost in terms of money, time and effort.
The predominant issue at the site is the developments proposed cut/fill earthorks on the
moderate to steep slopes.
An assessment of the risk of slope instability has been carried out for the site, based on the
results of the investigation and experience in similar projects, provided that development of
the site is carried out in accordance with good engineering practice for hillside
developments and the recommendations within this report.
It is considered that the blanket overlay risk rating is reduced by the following site
conditions:
No evidence of slumping/slip in rock faces in existing cut embankments;
Relatively shallow soils overlying stable bedrock strata (typically less than 1,000mm);
No previous known or mapped landslips on or close to site;
Ground water not evident during site testing and not generally associated with the
geology and elevation of the site on a ridge line;
Very little surface water is naturally (or otherwise) directed towards the site as the
development area is on the crest or summit of a ridge line.
Table 2 – Slope Instability Risk Assessment to Property
Hazard Likelihood Consequence Assessed Risk Comments
to Property
1.
Shallow slumping, Possible Minor Moderate Mitigation Measures Required:
rotational or slip in Risk
residual soils above The likelihood of failure of the
bedrock at house shallow soils overlying the
site weathered rock is possible with a
minor consequence.
Together with measures
recommended in this report
which includes founding all
footings/foundations into/on
sound weathered rock.
As per AGS 2007 the resultant risk
is low
2.
Failure in rock layer Barely Major Very Low The consequence of failure is
Credible major however the likelihood is
barely credible.
As per AGS 2007 the resultant risk
is very low
Suitable building methods must be adopted with treatment required as outlined following
in this report to provide for acceptable risk levels (very low –low risk).
PROPOSED NEW RESIDENCE PAGE 7 OF 10 4 March 2022
Page 9
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO
3.3 Geotechnical Constraints to Development
Conditions encountered on site generally support the landslip classifications given in the
reviewed mapping from the Noosa Council. That is, that the site contains regions of low,
moderate and high risk. It is considered that these risks can be effectively managed using a
number of techniques.
Recommended methods for managing landslip risk on site can be summarised as follows:
Manage cut/fill earthworks using engineering principals and practices;
Limit construction to areas of low to moderate risk as occurring;
Manage construction of services and structures to reduce likelihood of instability;
Found structures on underlying massive rock formation.
4.0 DESCRIPTION OF PROPOSED DEVELOPMENT
The proposed development consists of a single level dwelling on a concrete slab on the site
with elevated timber deck attached to the south east side. The development will require
earthworks for access construction, cut/fill earthworks for building site preparations,
excavations of footings/foundations and installation of services. Earthworks will also be
required for site drainage works.
4.1 Potential Geotechnical Effects
Potential geotechnical effects from site development are varied, and can be managed by
giving due consideration to site constraints during design and throughout construction. In
particular, the management of earthworks, stormwater drainage and sewer excavations on
the site will be important. Recommendations for limiting the impact of various elements of
the land development process are included in the following section, with additional
information included in Appendix C, “Guidelines for Hillside Construction”.
5.0 ASSESSMENT OF DEVELOPMENT IMPACTS
5.1 Roadworks, Driveways & Other Pavements
Entry to the site follows the existing concrete driveway access across the creek line where
the track is a rough dirt track aligned to the centre of the ridge line. The driveway is
proposed to be realigned to the north west side boundary up to the house site.
Figure 6 Alignment of proposed driveway
PROPOSED NEW RESIDENCE PAGE 8 OF 10 4 March 2022
Page 10
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO When building/construction works are complete a permanent all weather driveway will be constructed. Pavements should be sealed, either asphalt or concrete with adequate surface and subsurface drainage provided. 5.2 Earthworks Earthworks should be limited to building site preparation, access construction, service trenching and site drainage. Due to the moderate to steep slope of the site no unapproved earthworks (cut/fills) is to take place in the designated building envelope unless certified by a suitable geotechnical engineer. Where not specifically shown or detailed on the Site Earthworks-Drainage plan by E.B.I.S.(drawing number A3-210417-DW1) general requirements for earthworks and filling on steep or sloping sites where approved by a suitable geotechnical engineer is:- Cut embankments/batters where not retained should not exceed 1V:2H and must be limited to no greater than 1 metre in height unless retained by an engineer designed retaining wall structure. Fill embankments should be keyed into the natural ground when constructed on slopes greater than 15%. All fill should be placed as controlled fill as defined in AS 3798 – “Guidelines on earthworks for commercial and residential developments”. For specific details refer to Site Earthworks – Drainage Plan A3-210417-DW1. 5.3 Foundations We recommend that foundations for dwelling and associated structures be founded into/on sound underlying weathered rock. 5.4 Surface Drainage The site should be profiled prior to construction so that water drains away from the proposed building works. The site drainage should be maintained after completion of the building so that water does not pond next to the footings. On predominantly clay sites the moisture content of the soil should be monitored prior to the commencement of construction and maintained as set out in the CSIRO publication "Guide to Home Owners on Foundation Maintenance and Footing Performance". Refer to CSIRO website www.publish.csiro.au/pid/7076.htm. It is recommended surface water diversion swales be provided along the top side of the site in the early stages of construction. Surface water should be directed to existing drainage routes in undisturbed ground. Swales should also be provided to redirect water immediately above any embankments, retaining structures or earthworks areas. In addition, permanent drainage should be provided behind any retaining structures. Erosion and sediment control measures will be necessary during any earthworks. PROPOSED NEW RESIDENCE PAGE 9 OF 10 4 March 2022
Page 11
LOT 21 (16) PINES ROAD, COOROY EBIS REFERENCE NO: 210417-SU/GEO Drainage lines should be installed to direct roof water to appropriate discharge points. Level spreaders, energy dissipaters and other forms of scour protection will be required at all drainage outlets. Subsurface disposal of collected stormwater is not permitted due to the potential for contributing to slope instability and the reactive nature of the subgrade material. 5.5 Onsite Waste Treatment & Disposal EBIS has undertaken testing report and design for onsite effluent treatment and disposal and the siting of the land application area will not cause adverse effects to slope stability. Figure 7 Proposed location of onsite effluent disposal area 6.0 SUMMARY & CONCLUSIONS EBIS has undertaken the design for development to provide a very low risk of instability and to have a safety factor of greater than 1.5. Having given due consideration to all relevant issues including access, topography, geological conditions and drainage, the proposed location of the dwelling on the site is considered to be appropriate. In accordance with the General Land Use and Development on steep land, due regard has been given to the proposed building, and foundations. We have also assessed the surface drainage and stormwater system (see drawing No: A3-210417-DW1) and sewage disposal (see our onsite effluent disposal report 210417-ED and plans A3-210417-ED1 and consider these will not adversely affect the site stability of this site and adjoining allotments. It is advisable that a final inspection and evaluation of the site works including cuts/fills retaining walls and surface and subsurface drainage systems be undertaken by a competent person. This is to ensure general compliance to the above recommendations and sound building practices on steep and sloping sites. Ye BE. (civil), CP. Eng, MALE. Aust, RP.E.O. No. 4177, Vic EB 19910 PROPOSED NEW RESIDENCE PAGE 10 OF 10 15 February 2022
Page 12
DESIGN IN ACCORDANCE WITH THE QUEENSLAND HOME
BUILDING CODE, AS 1684.2 N3 CLASSIFICATION, BUILDING
CODE OF AUSTRALIA AND THE STANDARD BUILDING BY-LAWS,
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PROPERTY
DESCRIPTION
LOT: 21 —-SP308033
LOCALITY: COOROY
LOCAL GOV.: NOOSA SHIRE COUNCIL
AREA: 3874002/3.874h2
SITE CALCULATIONS
SITE AREA = 38740nF
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“APPROXIMATE LINE OF DRIVEWAY, EXACT
LOCATION TO BE DETERMINED ON SITE WITH f &
BUILDER. DRIVEWAY TO COMPLY i =
WITH LOCAL COUNCIL REQUIREMENTS / A & g
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GENERAL NOTES ®
t AL UATERALS GALL EE NE, MBER AO ORANER:TOLOCAL PROPOSED |
z TOENGNEERDETALS,
Fagmics To wave soul eorTens a SLECTRGAN,TOLOCA: ALTHORSTY GARAGE |
3% ‘BLAB; TO ENGINEER DETALS 6. BRICKLAYER: GALVINISED WALL TIES
UNDERLAY WITH 200mm POL! 4 ROWAT 2:
WAT ‘MEMBRANE AND ALL UNE ANO $ ROW IN THE SECOND |
PROTRUSIONS, CAST ON 50mm SAND ‘BED JOINT FROM TOP OF WALL AND
Conenere sreenomito| PROnOe WEEP HOLES G@ cn ALONG /
aon Ue eer fo BLNET AREA 7L00R AND shOER FLogRS PROPOSED
‘ BER RANI ALLENS AS * _facounlvinmibe seenon sa. DWELLING
PER CONNECTION DETARS AND GOOD &
1°. BUILDER TOCHECK ANO CONFIRN ALL Lé x
5 ‘UNINGS: AS PER BURLDERS SPECIFICATIONS, MEASUREMENTS PRIOR TO é
. TOCENGONCONGRETEROOETEES. WRITENDWENGINS TARE PRECEDENCE AT 7 é
Peer Manse ara” eee / C & H FRASER
ACTURERS SPECHICA
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EASEMENTS, STORMWATER & SEWER PRIOR: ‘APPROXIMATE LOCATION
SF EASEMENTS. STC age : OF WATERTANKS, EXACT COOROY QLD
SITE PLAN te.
& sow: 111500 shoes «2 ot 13
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WD104 - WORKING DRAWINGS
Page 13
FILL BENCH TO BE CONSTRUCTED DURING HOUSE PAD
EARTHWORKS:
* SITETO BE BENCHED PRIOR TO FILLING
PROPOSED ALL WEATHER DRIVEWAY WITH © CLEAN FILL TO BE PLACED IN LAYERS NOT EXCEEDING
PAVEMENTS TO BE SEALED WITH EITHER ASPHALT 200mm THICKNESS AND COMPACTED TO Min 957
PROPERTY OR CONCRETE WITH ADEQUATE SURFACE AND STANDARD COMPACTION WHERE NO STRUCTURES ARE
BOUNDARY] SUBSURFACE DRAINAGE - ALL DETAILS TO BE PROPOSED (IF STRUCTURES ARE PROPOSED COMPACT
CONFIRMED TO 98% STANDARD COMPACTION)
* APPROPRIATE COMPACTION TESTS TO BE CARRIED OUT
DURING COMPACTION
* _ FILLEMBANKMENT SLOPES SHOULD NOT EXCEED A ae
Im SLOPE OF 1 VERTICAL TO 3 HORIZONTAL (WHERE /
pm y GRASSED) OR 1 VERTICAL TO 2 HORIZONTAL IF
APRON SO EXT VER FOP SUITABLY ROLLED AND LANDSCAPED/ PLANTED - /
OF CUT EMBANKMENT UNLESS SPEC}FIED OTHERWISE BY ENGINEER /
/ CUT EMBANKMENT WITH HARD
CONCRETE SPOON DRAIN 1 SHALEY ROCK EVIDENT IN CUTTING
TO BE CONSTRUCTED AT TOP BUILDING PAD TO BE GRADED TO PROPOSED Ké /
OF CUT EMBANKMENT \ 1.5 MAX SLOPE AWAY FROM PROPOSED RESIDENCE ss 4
RESIDENCE AS REQUIRED PSu) >
<—\— h < < Ss UNSEALED TRACK
S
oy
PROPOSED FILL BENCH:
SPOON DRAIN TO BE CONSTRUCTED » / « _SITETO BE BENCHED PRIOR TO FILLING
ATTOE OF CUT EMBANKMENT 7 / * CLEAN FILL TO BE PLACED IN LAYERS NOT
SECTION AA PROPOSED EXCEEDING 200mm THICKNESS AND
CONCRETE COMPACTED TO Min 95% STANDARD
URN AROUND \ COMPACTION WHERE NO STRUCTURES ARE
ROCK SPALL/ SCOUR PROTECTION TO BE ea Js > PROPOSED (IF STRUCTURES ARE PROPOSED
CONSTRUCTED AT TERMINATION POINT N 4 COMPACT TO 98% STANDARD COMPACTION)
(OF SURFACE DRAINS é «APPROPRIATE COMPACTION TESTS TO BE
A CARRIED OUT DURING COMPACTION
Y SY + FILLEMBANKMENT SLOPES SHOULD NOT EXCEED
ROCK SPALL/ SCOUR PROTECTION st “LO _~ A SLOPE OF 1 VERTICAL TO 3 HORIZONTAL
NOTE: WHERE SURFACE DRAINS COMBINE SN, YY e NX (WHERE GRASSED) OR 1 VERTICAL TO 2
xy HORIZONTAL IF SUITABLY ROLLED AND
ALL DETAILS ON THIS PLAN ARE SCHEMATIC ONLY. xX XQ .. [ANDSCAPED/ PLANTED - UNLESS $PECIFIED
SPOON DRAINS TO BE CONSTRUCTED AT
THIS PLAN IS NOT TO BE USED OR SCALED FROM
FOR CONSTRUCTION PURPOSES. DETAILS MAY NEED
TO BE ALTERED AS DEVELOPMENT PLANNING
PROGRESSES. ALL DETAILS MUST BE CONFIRMED BY
EBIS ENGINEERING PRIOR TO CONSTRUCTION.
TOP & TOE OF CUT EMBANKMENT
CUT-EMBANKMENT TO BE INSPECTED. BY GEOTECHNICAL ENGINEER. DURING.
EXCAVATION TO PROVIDE COMMENT ON CONDITION OF EMBANKMENT AND.
NOMINATE. AREAS THAT MAY NEED FURTHER TREATMENT (SPRAY CONCRETE
FINISHING) - DETAILS TO BE CONFIRMED ONSITE
PROPOSED BATTERED CUT EMBANKMEN
NOT TO EXCEED A MAXIMUM SLOPE OF
1.5 VERTICAL TO | HORIZONTAL UNLESS
STORM WATER, EARTHWORKS & EROSION CONTROL FOR STEEP
SITES
NOMINATED OTHERWISE BY ENGINEER
e Batters to cut embankmenis are not to exceed a slope of 1.5
vertical to 1 horizontal - All details of cut embankments to be
confirmed onsite by engineer.
e Fill embankments should be keyed into the natural ground when
constructed on slopes greater than 15%. Embankment slopes in
fill should not exceed a slope of | vertical to 3 horizontal (where
grassed).
e If fill embankment is suitably rolled during construction,
landscaped with coarse hoop pine bark (or similar) and planted
with suitable shrubs, fill embankment slopes should not exceed a
slope of | vertical to 2 horizontal - all details to be confirmed by
owner.
e Grass to be planted on fill slopes to minimise soil erosion.
e Surface spoon drains at the top and toe of the cut batters/
retaining structures.
® At the ends of the spoon drains provide rock spalls fo disperse
OTHERWISE BY ENGINEER
PROPOSED
S RESIDENCE NSA
6 OS < P<]
S Nf XY Lp [D>
\/4
A
NY PROPOSED LAND
APPLICATION AREA FOR
/ ONSITE EFFLUENT DISPOSAL -
FOR ALL DETAILS, REFER TO
EBIS REPORT 210417-ED AND
BUILDING PAD TO BE GRADED SS DESIGN PLAN A3-210417-ED1
TO SLOPE AWAY FROM
PROPOSED RESIDENCE AS. \\
REQUIRED >,
\ LI APPROXIMATE LOCATION
NOTE: OF PROPOSED PARTIALLY
ENSURE OVERFLOW FROM PROPOSED RAINWATER TANKS IS <A I INGROUND WATER TANKS -
PIPED SUB-SURFACE & DISCHARGED TO AN APPROVED SAS ~ C) FINAL LOCATION TO BE
LOCATION, THE USE OF ROCK SPALLS, SCOUR PROTECTION PASS CONFIRMED
AND ENERGY DISSIPATERS MAY BE REQUIRED AT OUTLETS - ALL S
DETAILS TO BE CONFIRMED SS —
~
ROCK SPALL/ SCOUR PROTECTION =
WHERE SURFACE DRAINS COMBINE
SPOON DRAIN TO BE CONSTRUCTED,
ABOVE EXISTING CUT EMBANKMENT
any concentrated flow to minimise erosion.
DETAILS ON THIS PLAN ARE
APPROXIMATE ONLY. DO NOT
SCALE FROM PLAN FOR
CONSTRUCTION PURPOSES.
ALL DETAILS OF SITE DRAINAGE &
EARTHWORKS ARE TO BE INSPECTED &
NOTE:
__CONFIRMED BY EBIS
INDIVIDUAL ROCK SPALL/ SCOUR
PROTECTION TO BE CONSTRUCTED AT
TERMINATION POINTS OF SURFACE
DRAINS & WATER TANK OVERFLOW
APPROXIMATE LOCATION FOR PROPOSED HOUSE HOLD
SEWAGE TREATMENT SYSTEM - FOR ALL DETAILS, REFER TO EBIS.
REPORT 210417-ED AND DESIGN PLAN A3-210417-ED1
ORIGINAL ISSUE 04.02.2022
Engineering & Building Investigation Services Proposed Residence
Unit 1/4 Textile Ave, Warana = PO Box 973 Buddina 4575
Phone 07 54369199 Fax 54369198
EBIs
at: Lot 21 (No.14) Pines Road Cooroy
Client : DJ Sommer Homes (Pines Road)
EARTHWORKS & SITE DRAINAGE PLAN
Drawing No. A3-210417-DW1
Scale: nts
February 2022 | Drawn: LM
Checkese G9]
Page 14
=). Proposed fag Residence Site i MM Very High Hazard Area p High Hazerd Area Moderate Hazard Area Landslip Hazard Overlay Map cours of Noosa Plan 2020 <=. = aE
Page 15
Cooroy Belli Creek Road . Approximate Proposed Residence Site - Geology = Rk - Kin Kin Beds - Strongly cleaved and commonly kinked mudstone with thin siltstone laminae; minor volcanilithic sandstone vA fs. Geology Map - Courtesy of QLD Globe Mapping System
Page 16
LANDSLIDE RISK MANAGEMENT AGS SUB-COMMITTEE
Figure J1 Illustrations of Good and Poor Hillside Practice
92 Australian Geomechanics – March 2000
Page 17
LANDSLIDE RISK MANAGEMENT AGS SUB-COMMITTEE
APPENDIX J
SOME GUIDELINES FOR HILLSIDE CONSTRUCTION
GOOD ENGINEERING PRACTICE POOR ENGINEERING PRACTICE
ADVICE
GEOTECHNICAL Obtain advice from a qualified, experienced geotechnical consultant at early Prepare detailed plan and start site works before
ASSESSMENT stage of planning and before site works. geotechnical advice.
PLANNING
SITE PLANNING Having obtained geotechnical advice, plan the development with the risk Plan development without regard for the Risk.
arising from the identified hazards and consequences in mind.
DESIGN AND CONSTRUCTION
HOUSE DESIGN Use flexible structures which incorporate properly designed brickwork, timber Floor plans which require extensive cutting and
or steel frames, timber or panel cladding. filling.
Consider use of split levels. Movement intolerant structures.
Use decks for recreational areas where appropriate.
SITE CLEARING Retain natural vegetation wherever practicable. Indiscriminately clear the site.
ACCESS & Satisfy requirements below for cuts, fills, retaining walls and drainage. Excavate and fill for site access before
DRIVEWAYS Council specifications for grades may need to be modified. geotechnical advice.
Driveways and parking areas may need to be fully supported on piers.
EARTHWORKS Retain natural contours wherever possible. Indiscriminant bulk earthworks.
CUTS Minimise depth. Large scale cuts and benching.
Support with engineered retaining walls or batter to appropriate slope. Unsupported cuts.
Provide drainage measures and erosion control. Ignore drainage requirements
FILLS Minimise height. Loose or poorly compacted fill, which if it fails,
Strip vegetation and topsoil and key into natural slopes prior to filling. may flow a considerable distance including
Use clean fill materials and compact to engineering standards. onto property below.
Batter to appropriate slope or support with engineered retaining wall. Block natural drainage lines.
Provide surface drainage and appropriate subsurface drainage. Fill over existing vegetation and topsoil.
Include stumps, trees, vegetation, topsoil,
boulders, building rubble etc in fill.
R OCK OUTCROPS Remove or stabilise boulders which may have unacceptable risk. Disturb or undercut detached blocks or
& BOULDERS Support rock faces where necessary. boulders.
RETAINING Engineer design to resist applied soil and water forces. Construct a structurally inadequate wall such as
WALLS Found on rock where practicable. sandstone flagging, brick or unreinforced
Provide subsurface drainage within wall backfill and surface drainage on slope blockwork.
above. Lack of subsurface drains and weepholes.
Construct wall as soon as possible after cut/fill operation.
FOOTINGS Found within rock where practicable. Found on topsoil, loose fill, detached boulders
Use rows of piers or strip footings oriented up and down slope. or undercut cliffs.
Design for lateral creep pressures if necessary.
Backfill footing excavations to exclude ingress of surface water.
SWIMMING POOLS Engineer designed.
Support on piers to rock where practicable.
Provide with under-drainage and gravity drain outlet where practicable.
Design for high soil pressures which may develop on uphill side whilst there
may be little or no lateral support on downhill side.
DRAINAGE
SURFACE Provide at tops of cut and fill slopes. Discharge at top of fills and cuts.
Discharge to street drainage or natural water courses. Allow water to pond on bench areas.
Provide general falls to prevent blockage by siltation and incorporate silt traps.
Line to minimise infiltration and make flexible where possible.
Special structures to dissipate energy at changes of slope and/or direction.
SUBSURFACE Provide filter around subsurface drain. Discharge roof runoff into absorption trenches.
Provide drain behind retaining walls.
Use flexible pipelines with access for maintenance.
Prevent inflow of surface water.
SEPTIC & Usually requires pump-out or mains sewer systems; absorption trenches may Discharge sullage directly onto and into slopes.
SULLAGE be possible in some areas if risk is acceptable. Use absorption trenches without consideration
Storage tanks should be water-tight and adequately founded. of landslide risk.
EROSION Control erosion as this may lead to instability. Failure to observe earthworks and drainage
CONTROL & Revegetate cleared area. recommendations when landscaping.
LANDSCAPING
DRAWINGS AND SITE VISITS DURING CONSTRUCTION
DRAWINGS Building Application drawings should be viewed by geotechnical consultant
SITE VISITS Site Visits by consultant may be appropriate during construction/
INSPECTION AND MAINTENANCE BY OWNER
OWNER’S Clean drainage systems; repair broken joints in drains and leaks in supply
RESPONSIBILITY pipes.
Where structural distress is evident see advice.
If seepage observed, determine causes or seek advice on consequences.
Australian Geomechanics – March 2000 91
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PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007 APPENDIX C: LANDSLIDE RISK ASSESSMENT QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY QUALITATIVE MEASURES OF LIKELIHOOD Approximate Annual Probability Implied Indicative Landslide peseription peseriptor Level Indicative Notional Recurrence Interval P P Value Boundary 10! 5x102 10 years 0 The event is expected to occur over the design life. ALMOST CERTAIN A years 7 a 7 7 ~onditions Ov! 102 100 years event will probably occur under adverse conditions over the LIKELY B ech 5x107 200 years gn - — - - = 10° 7 1000 years 2000 vears The event could occur under adverse conditions over the design life. | POSSIBLE Cc 10" 5x10 10,000 years : The event might occur under very adverse circumstances over the UNLIKELY D 10° Sxl0° 20,000 years Teagan conceivable but only under exceptional circumstances 100,000 years he event is conceivable but only under exceptional circumstances | p app E 5x10 200,000 years over the design life. 10° 1,000,000 years . The event is inconceivable or fanciful over the design life. BARELY CREDIBLE Note: (1) The table should be used from left to right; use Approximate Annual Probability or Description to assign Descriptor, not vice versa. QUALITATIVE MEASURES OF CONSEQUENCES TO PROPERTY Approximate Cost of Damage Indicative Notional Description Descriptor Level Value Boundary 200% Structure(s) completely destroyed and/or large scale damage requiring major engineering works for CATASTROPHIC 1 stabilisation. Could cause at least one adjacent property major consequence damage. 100% E = ; : er 0, xtensive damage to most of structure, and/or extending beyond site boundaries requiring significant 60% “eat, : : MAJOR 2 40% stabilisation works. Could cause at least one adjacent property medium consequence damage. 20% Moderate damage to some of structure, and/or significant part of site requiring large stabilisation works. MEDIUM 3 ° 10% Could cause at least one adjacent property minor consequence damage. 5% 1% ° Limited damage to part of structure, and/or part of site requiring some reinstatement stabilisation works. MINOR 4 05% Little damage. (Note for high probability event (Almost Certain), this category may be subdivided at a INSIGNIFICANT 5 notional boundary of 0.1%, See Risk Matrix.) Notes: (2) The Approximate Cost of Damage is expressed as a percentage of market value, being the cost cf the improved value of the unaffected property which includes the land plus the unaffected structures. (3) The Approximate Cost is to be an estimate of the direct cost of the damage, such as the cost of reinstatement of the damaged portion of the property (land plus structures), stabilisation works required to render the site to tolerable risk level for the landslide which has occurred and professional design fees, and consequential costs such as legal fees, temporary accommodation. It does not include additional stabilisation works to address other landslides which may affect the property. (4) The table should be used from left to right; use Approximate Cost of Damage or Description to assign Descriptor, not vice versa 91 Australian Geomechanics Vol 42 No 1 March 2007
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QUALITATIVE RISK ANALYSIS MATRIX - PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007 APPENDIX C: —- QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY (CONTINUED) LEVEL OF RISK TO PROPERTY LIKELIHOOD CONSEQUENCES TO PROPERTY (With Indicative Approximate Cost of Damage) Indicative Value of 1: CATASTROPHIC 2: MAJOR 3: MEDIUM 4: MINOR 3: Approximate Annual 200% 60% 20% 5% INSIGNIFICANT Probability 0.5% A ALMOST CERTAIN 10" H Mor L (5) B LIKELY 10° M L Cc POSSIBLE 10° M VL D UNLIKELY 104 L VL E RARE 10° VL VL F BARELY CREDIBLE 10° L VL VL VL VL Notes: (5) For Cell A5, may be subdivided such that a consequence of less than 0.1% is Low Risk. (6) When considering a risk assessment it must be clearly stated whether it is for existing conditions or with risk control measures which may not be implemented at the current time. RISK LEVEL IMPLICATIONS Risk Level HIGH RISK Example Implications (7) Unacceptable without treatment. Extensive detailed investigation and research, planning and implementation of treatment options essential to reduce risk to Low; may be too expensive and not practical. Work likely to cost more than value of the property. Unacceptable without treatment. Detailed investigation, planning and implementation of treatment options required to reduce tisk to Low. Work would cost a substantial sum in relation to the value of the property. MODERATE RISK May be tolerated in certain circumstances (subject to regulator’s approval) but requires investigation, planning and. implementation of treatment options to reduce the risk to Low. Treatment options to reduce to Low risk should be implemented as soon as practicable. L LOW RISK Usually acceptable to regulators. Where treatment has been required to reduce the risk to this level, ongoing maintenance is required. VL VERY LOW RISK Acceptable. Manage by normal slope maintenance procedures. Note: (7) given as a general guide. 92 The implications for a pazticular situation are to be determined by all parties to the risk assessment and may depend on the nature of the property at risk; these are only Australian Geomechanics Vol 42 No 1 March 2007