Council archive · source document
Attachment 5 - Slope Stability Assessment · RAL20/0005
22 July 2016 Project No. 16162-001-Rev0 Mr Peter Loxton Email: [email protected] SLOPE STABILITY ASSESSMENT FOR PROPOSED ADDITION TO RESIDENCE 20 MITTI STREET, NOOSA HEADS 1.0 INTRODUCTION As requested, Tectonic has undertaken a slope stability assessment for a proposed addition at 20 Mitti Street, Noosa Heads. This report presents the results of our slope stability assessment, together with geotechnical advice for the development. In summary, subject to implementation of the recommendations made herein, there is a Very Low Risk of slope instability affecting the proposed addition in accordance with the Australian Geomechanics Society “Guidelines for Landslide Risk Management”, dated March 2007 (AGS 2007). 1.1 Details of Site and Development The property is described as Lot 2 on RP173874, covers a total area of 1,373 m², and is located within the Noosa Shire Council (NSC) area. The site has frontage via an access ‘handle’ to Mitti Street to the west. Existing residential buildings surround the site, except to the east where the property borders Noosa National Park. Text Figure 1 illustrates the site location. A detailed description of site features is given in Section 2. Site Text Figure 1: Site location (courtesy Qld Globe) Tectonic Geotechnical Pty Ltd PO Box 899, Buderim, QLD 4556 Mobile 0437 755 750 / 0437 756 711 www.tectonicgeo.com.au A.B.N. 83 165 727 828
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Design drawings prepared by Void (Ref. VBD 15 10, Sheets 1 to 28, Rev 2, dated 7 July 2016) indicate
that an existing residence located in the western part of the site will be retained, with the proposed addition
to comprise a free-standing building close to the eastern boundary (Ref. Text Figure 2). Construction will
be a combination of masonry and light-weight materials including core-filled blockwork, timber framed walls
with cladding, suspended concrete floors, floors supported by joists, all with a sheet metal roof.
Structural drawings prepared by Barlow Shelley Consulting Engineers (Ref. 1441, ST01 to ST12, Rev A,
dated 15 July 2016) indicate that the addition will be supported by sub-floor walls and posts founded on a
combination of strip and pad footings. Panels for a proposed carport slab on the ground level at the
northern end of the building will sit on up to approximately 0.5 m of imported fill. Apparently due to the
position of the building within a watercourse, and the anticipated presence of loose/wet materials, the
structural design calls for all footings to be supported using 7 tonne capacity screw piles.
The addition will be connected to existing town water and sewerage. An existing sewer main traverses the
western part of the site.
Text Figure 2: Proposed site plan and section (D-D) through addition
1.2 Method and Scope of Investigation
As part of our slope stability assessment, a desk-top study was carried out comprising a review of
published geological and slope stability maps, together with a soil test report by CSI dated 19 July 2016
(Job No. 10549).
A walk-over survey was conducted in order to make an appraisal of the general condition of the site in
regards to topography, drainage, vegetation cover, geology, erosion, condition of existing structures and
slope stability. The walk-over survey was carried out by an experienced geotechnical engineer from
Tectonic on 18 July 2016.
The results of the desk-top study and walk-over survey are included in Section 2 below.
1.3 Qualifications of Responsible Engineer
This report has been prepared by Mr Ashley Davey, an RPEQ with more than 20 years of experience in
geotechnical engineering, including a number of slope stability projects.
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2.0 DESCRIPTION OF EXISTING CONDITIONS
2.1 Geology
Available geological information1 indicates that the site is underlain by the late Triassic to Jurassic age Tiaro
Coal Measures, which comprise predominantly sandstone and siltstone.
The CSI investigation comprised two boreholes (BH1 and BH2) drilled to depths of up to 1.9 m (BGL) by
hand auger at the southern and northern ends of the proposed addition, respectively. In situ soil strength
was assessed by conducting dynamic cone penetrometer (DCP) tests adjacent to each of the boreholes,
extending to depths of up to 3.5 m BGL.
The boreholes and DCPs indicate very loose natural clayey sand to depths of between 0.4 m and 1.1 m
BGL, then loose sand, becoming dense from about 1.5 m to 2 m BGL, and possibly tending dense from
approximately 2.5 m to 3.5 m BGL (then extending to the depth of investigation). These soils are inferred to
comprise alluvium deposited within the watercourse, and are likely to overlie stiff residual clays and
weathered rock of the Tiaro Coal Measures at depth.
Groundwater was encountered at 0.4 m BGL in the CSI boreholes, with the sands described as “wet”.
CSI has classified the site as Class P (per AS2870) due to the presence of low bearing capacity of the
sands, however indicate that the site has the characteristics of Class S (low reactivity to normal soil moisture
content changes).
2.2 Topography
As shown in Text Figure 3, the proposed building site (at the rear of the property) is located at the western
edge of a natural watercourse, where the ground surface slopes very gently (<1°) towards the north. In the
western part of the block, the natural ground surface rises up to a well-rounded ridge which peaks further
west near Alderley Terrace (likely underlain by residual soils and weathered rocks of the Tiaro Coal
Measures). Ground slopes in this part of the site form a relatively planar surface and were recorded using a
hand held clinometer ranging up to about 10° (18%) (Ref. Text Figure 4 over page). Cut/fill batters around
the existing house have formed a level carparking area at the front (Ref Text Figure 5 over page).
Site
Text Figure 3: Local ground surface contours (courtesy NSC MapInfo)
1
1:100,000 Gympie Special Geology Map, Sheet 9445 & Part 9545, DME, 1999
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Text Figure 4: Slope along access driveway (neighbouring property to north in background)
Text Figure 5: Level area at front of existing residence
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2.3 Groundwater
As mentioned above, groundwater was encountered in the CSI boreholes at shallow depth. The ground
surface across the proposed addition footprint was noted to be relatively saturated at the time of our walk-
over.
2.4 Surface Drainage
Due to the low-lying nature of the site, and very low gradients, surface water run-off is expected to be
relatively slow, leading to the saturated soils observed at the surface and in the CSI boreholes. It is
possible that the site may be subjected to flooding during high intensity rainfall events (this should be
assessed by a suitably qualified and experienced hydraulic engineer). As shown in Text Figure 2 and
illustrated in Text Figure 6, two watercourses not more than about 1 m wide meander across the proposed
building site and held water up to about 0.5 m deep at the time of the walk-over. No signs of soil erosion
were observed during our visit.
Text Figure 6: Existing watercourse
2.5 Vegetation
At the time of the site visit, the proposed building site had a dense canopy of mostly paperbark trees
estimated up to 15 m tall, with a relatively open understorey including palms and ferns. The sloping western
part of the site contained some tall gum trees, with straight and ‘plumb’ trunks (Ref. Text Figure 7).
Text Figure 7: Level area at front of existing residence
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2.6 Buildings and Other Structures
The existing residence comprises a two storey structure of solid brick construction that appeared to be in
very good structural condition from our external assessment during our site visit (Ref. Text Figure 8).
Although the asphalt driveway was noted to be in poor condition, this appears to be due to ageing in
combination with excessive wear. Mitti Street comprises an asphalt pavement with upright concrete kerb
and channel which did not show any signs of significant distress (Ref. Text Figure 9).
Text Figure 8: No cracking in high brick wall along rear of residence
Text Figure 9: Mitti Street along site frontage, view looking south
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3.0 ASSESSMENT OF LAND STABILITY
3.1 Existing Conditions
The NSC Landslide Hazard Overlay map (Refer Text Figure 10 below) indicates that the site is located within
a Landslide Hazard Area (pink shading).
Site
Text Figure 10: Extract from Noosa Council Natural Hazard: Landslide & Flooding Overlay
It should be noted that the NSC overlay map is a broad-scale indication of the potential landslide
susceptibility only and is superseded by site specific investigation and analysis works. At the time of our
visit, the site did not exhibit any indicators of slope instability, with the ground surface near level.
3.2 Stability Assessment
The risk assessment for this project has been carried out following AGS 2007 Practice Note Guidelines for
Landslide Risk Management. Relative levels of risk and their implications are given in Table 1 below and the
Qualitative Terminology for Use in Assessing Risk to Property is attached.
Table 1: Stability Risk Levels
Risk Level Example Implications(1)
Unacceptable without treatment. Extensive detailed investigation and research, planning
Very High
VH and implementation of treatment options essential to reduce risk to Low; may be too
Risk
expensive and not practical. Work likely to cost more than value of property.
Unacceptable without treatment. Detailed investigation, planning and implementation of
H High Risk treatment options required to reduce risk to Low. Work would cost a substantial sum in
relation to the value of the property.
May be tolerated in certain circumstances (subject to regulators’ approval) but requires
Moderate
M investigation, planning and implementation of treatment options to reduce risk to Low.
Risk
Treatment options to reduce to Low risk should be implemented as soon as practicable.
Usually acceptable to regulators. Where treatment has been required to reduce the risk
L Low Risk
to this level, ongoing maintenance required.
Very Low
VL Acceptable. Manage by normal slope maintenance procedures.
Risk
Note: (1) The implications for a particular 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 given as a general guide.
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Considering the existing site conditions (Ref. Section 2), and subject to the implementation of
recommendations given below, it is our opinion that there will be a Very Low (VL) Risk of global slope
instability affecting the proposed addition. Regulators (NSC) normally require that a Very Low or Low Risk of
landslide affecting property must be demonstrated to enable development approval. Summarised in Table 2
below is our qualitative assessment of landslide risk for the site. A summary of qualitative terminology for
use in assessing risk to property is attached (taken from AGS 2007).
Table 2: Details of Qualitative Risk Assessment for Property (AGS 2007)
Assessed
Hazard Likelihood Consequence
Risk
Comments
The likelihood of shallow erosion of the loose sand
is assessed as Possible on this site given the
1: Shallow failure/erosion geomorphological position. However, subject to
through loose sand above the Possible Insignificant Very Low implementation of the recommendations made in
foundation depth Section 4, the consequence of such shallow erosion
would be Insignificant, with the resultant risk to the
addition being Very Low.
The likelihood of a deep failure through the medium
dense (or denser) sand is assessed as Barely
2: Deep failure through
Barely Credible due to the near level ground slope through
medium dense (or denser) sand Major Very Low
Credible the building area. Although the consequence of such
below the foundation depth
a failure could be Major, the resultant risk is Very Low
as per AGS 2007.
The potential impacts on slope stability of the development components have been assessed, and the
measures recommended below in Section 4 have been designed to mitigate those impacts.
4.0 RECOMMENDATIONS
General recommendations to help maintain the stability of the site are given in the document “Some
Guidelines for Hillside Construction”, which is attached.
4.1 Earthworks
New fill should not exceed 0.5 m depth and must be fully enclosed by an engineer designed structure (e.g.
under the carport slab as proposed). Given the position of the addition at the edge of a watercourse,
permanent cut batter slopes are not recommended.
Any organic rich topsoil and severely root affected soils must be stripped and removed from the building area.
Due to the wet and loose nature of the natural subgrade, it will likely be necessary to place a ‘rock blanket’
across any fill subgrades (as proposed in the structural design under the carport slab). This could comprise a
non-woven geosynthetic filter fabric (e.g. Bidim) on the natural soil (to prevent upward migration of ‘fines’ by
‘pumping’ during earthworks), then an imported rock fill product (e.g. 75 minus).
Fill materials should be compacted at moisture contents within the range of -2% to +2% of optimum moisture
content for Standard Compaction. Confirmatory testing must be carried out at regular intervals and further
details for control and testing of fill are given in Australian Standard AS 3798-2007 “Guidelines on Earthworks
for Commercial and Residential Developments”. Select fill should have a maximum particle size of 100mm for
an uncompacted layer thickness of 200mm and shall be compacted by repeated rolling with a small
compactor to achieve a dry density ratio of at least 95% of the Standard Maximum Dry Density for cohesive
soils, or 70% Dry Density Index for any imported cohesionless soils.
Temporary excavations in natural sands may be battered at a maximum slope of 1V:2H. Flatter batters may
be required if groundwater seepage is encountered, or if excavations are carried out during periods of wet
weather. Depending on the locations and depths of any excavations relative to existing structures, it may be
necessary to install temporary shoring (e.g. sheet piles).
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Any bared areas must be revegetated with similar native shrubs and trees, and ground cover.
Due to the close proximity of a tennis court on the neighbouring property to the north, it is essential that
earthworks be carried out in a fashion to minimise ground vibrations. No vibratory equipment should be used.
It would be prudent to conduct a dilapidation survey of nearby structures prior to construction in order to
establish a ‘baseline’ of structural condition.
4.2 Footing Design
We concur with the structural design in that the proposed residence and any associated structures should be
supported on a piled footing system, with screw piles the preferred method given the ground conditions,
access, etc. Such piles must penetrate through any loose sands to found into medium dense (or denser)
natural sand. Based on the CSI boreholes, a minimum founding depth for piles of 3 m is recommended,
however care will need to be taken during installation to ensure that piles are not over extended. Footings
so founded may be designed using an allowable end bearing capacity of 300 kPa. Given the proposed loads
on the piles, to confirm pile toe levels for design, it would be prudent to conduct more detailed geotechnical
investigation (e.g. mechanical augering to greater depth) once vehicle access to the building site is available.
All footings must also found such that they are not adversely affected by any adjacent excavations, batter
slopes, trenches, or retaining walls that are not designed to support building loads. Footings should found at
least below a plane extending 1 m horizontally from the base of trenches/batter slopes/excavations/retaining
walls, then rising up at 1V:1H, as illustrated in the following diagram.
Text Figure 11: Footing depth required to prevent undermining
4.3 Retaining Structures
We recommend the following parameters may be adopted for retaining wall design:
Soil type Loose sand
Friction Angle: 27°
Active Earth Pressure Coefficient: 0.4
Passive Earth Pressure Coefficient: 2.6
Unit Weight: 18 kN/m³
These parameters do not include allowance for surcharge above the wall, or additional loads imposed by
sloping ground or hydrostatic pressure.
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4.4 Drainage
It is essential that finished gradients around the house are formed to ensure that natural runoff is directed
away from building walls and footings. Surface protection (e.g. proprietary matting in combination with
plantings, or rock ‘rip rap’) must also be placed to prevent erosion and undermining of any proposed
structures by possible stormwater flows.
Subsurface drainage must be installed behind retaining walls in order to prevent the development of
hydrostatic pressure (e.g. slotted ‘aggi’ pipe wrapped in filter ‘sock’ placed in gravel backfill).
All excess stormwater collected around the proposed residence (including overflow from rainwater tanks)
must be directed by pipes to the legal point of downstream discharge (presumably the existing watercourse).
5.0 SUMMARY & CONCLUSIONS
Based on the findings of our assessment we consider, from a geotechnical viewpoint, that the site is suitable
for the proposed addition and that there should be a Very Low Risk of slope instability. This advice is subject
to implementation of the recommendations given in this report.
6.0 LIMITATIONS
Your attention is drawn to the document Limitations, which is attached to this letter report.
Please contact the undersigned should you wish to discuss any of the above matters.
Yours faithfully
TECTONIC GEOTECHNICAL PTY LTD
Ashley Davey BEng (Geological) MIEAust RPEQ 8159
Director/Principal Geotechnical Engineer
Attachments: Qualitative Terminology for Use in Assessing Risk to Property
Some Guidelines for Hillside Construction
Limitations
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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
Description Descriptor Level
Indicative Notional Recurrence Interval
Value Boundary
10-1 5x10-2
10 years The event is expected to occur over the design life. ALMOST CERTAIN A
20 years The event will probably occur under adverse conditions over the
-2
10 100 years
design life.
LIKELY B
-3
-3 5x10 200 years
10 1000 years The event could occur under adverse conditions over the design life. POSSIBLE C
5x10-4 2000 years
The event might occur under very adverse circumstances over the
10-4 10,000 years
design life.
UNLIKELY D
-5 5x10-5 20,000 years
10 The event is conceivable but only under exceptional circumstances
100,000 years RARE E
over the design life.
-6 5x10-6 200,000 years
10 1,000,000 years The event is inconceivable or fanciful over the design life. BARELY CREDIBLE F
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
Description Descriptor Level
Indicative Notional
Value Boundary
Structure(s) completely destroyed and/or large scale damage requiring major engineering works for
200% CATASTROPHIC 1
stabilisation. Could cause at least one adjacent property major consequence damage.
100%
Extensive damage to most of structure, and/or extending beyond site boundaries requiring significant
60% MAJOR 2
stabilisation works. Could cause at least one adjacent property medium consequence damage.
40%
Moderate damage to some of structure, and/or significant part of site requiring large stabilisation works.
20% MEDIUM 3
Could cause at least one adjacent property minor consequence damage.
10%
5% 1% Limited damage to part of structure, and/or part of site requiring some reinstatement stabilisation works. MINOR 4
Little damage. (Note for high probability event (Almost Certain), this category may be subdivided at a
0.5% 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 of 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
Australian Geomechanics Vol 42 No 1 March 2007
Form No. 68039
68039 RL2Risk
Landslide August 2010
Management Issued 10/7/07
Page 12
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX C: – QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY (CONTINUED)
QUALITATIVE RISK ANALYSIS MATRIX – 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 5:
Approximate Annual 200% 60% 20% 5% INSIGNIFICANT
Probability 0.5%
A – ALMOST CERTAIN 10-1 VH VH VH H M or L (5)
-2
B - LIKELY 10 VH VH H M L
C - POSSIBLE 10-3 VH H M M VL
D - UNLIKELY 10-4 H M L L VL
-5
E - RARE 10 M L L VL VL
-6
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 Example Implications (7)
Unacceptable without treatment. Extensive detailed investigation and research, planning and implementation of treatment
VH VERY HIGH RISK 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
H HIGH RISK
risk to Low. Work would cost a substantial sum in relation to the value of the property.
May be tolerated in certain circumstances (subject to regulator’s approval) but requires investigation, planning and
M MODERATE RISK implementation of treatment options to reduce the risk to Low. Treatment options to reduce to Low risk should be
implemented as soon as practicable.
Usually acceptable to regulators. Where treatment has been required to reduce the risk to this level, ongoing maintenance is
L LOW RISK
required.
Acceptable. Manage by normal slope maintenance procedures.
VL VERY LOW RISK
Note: (7) The implications for a particular 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
given as a general guide.
Australian Geomechanics Vol 42 No 1 March 2007
Form No. Landslide
68039 68039 RL2Risk
August 2010
Management Issued 10/7/07
Page 13
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX G - SOME GUIDELINES FOR HILLSIDE CONSTRUCTION
GOOD ENGINEERING PRACTICE POOR ENGINEERING PRACTICE
ADVICE
GEOTECHNICAL Obtain advice from a qualified, experienced geotechnical practitioner 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
Use flexible structures which incorporate properly designed brickwork, timber Floor plans which require extensive cutting and
or steel frames, timber or panel cladding. filling.
HOUSE DESIGN
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. Indiscriminatory bulk earthworks.
Minimise depth. Large scale cuts and benching.
CUTS Support with engineered retaining walls or batter to appropriate slope. Unsupported cuts.
Provide drainage measures and erosion control. Ignore drainage requirements
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.
FILLS 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.
ROCK OUTCROPS Remove or stabilise boulders which may have unacceptable risk. Disturb or undercut detached blocks or
& BOULDERS Support rock faces where necessary. boulders.
Engineer design to resist applied soil and water forces. Construct a structurally inadequate wall such as
Found on rock where practicable. sandstone flagging, brick or unreinforced
RETAINING
Provide subsurface drainage within wall backfill and surface drainage on slope blockwork.
WALLS
above. Lack of subsurface drains and weepholes.
Construct wall as soon as possible after cut/fill operation.
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.
FOOTINGS
Design for lateral creep pressures if necessary.
Backfill footing excavations to exclude ingress of surface water.
Engineer designed.
Support on piers to rock where practicable.
SWIMMING POOLS 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
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.
SURFACE 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.
Provide filter around subsurface drain. Discharge roof runoff into absorption trenches.
Provide drain behind retaining walls.
SUBSURFACE
Use flexible pipelines with access for maintenance.
Prevent inflow of surface water.
Usually requires pump-out or mains sewer systems; absorption trenches may Discharge sullage directly onto and into slopes.
SEPTIC &
be possible in some areas if risk is acceptable. Use absorption trenches without consideration
SULLAGE
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 Vol 42 No 1 March 2007 113
Form No. 68029 RL2 August 2010
Page 14
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
114 Australian Geomechanics Vol 42 No 1 March 2007
Form No. 68029 RL2 August 2010
Page 15
LIMITATIONS This document has been prepared for the purpose outlined in Tectonic’s proposal and no responsibility is accepted for the use of this document, in whole or in part, for any other purpose. The scope of Tectonic’s Services are as described in Tectonic’s proposal, and are subject to restrictions and limitations. Tectonic did not perform a complete assessment of all possible conditions or circumstances that may exist at the site referenced in the report. If a service is not expressly indicated, do not assume it has been provided. If a matter is not addressed, do not assume that any determination has been made by Tectonic in regards to it. Conditions may exist which were undetectable given that economic and time constraints limit the practical extent of geotechnical investigation. Variations in conditions may occur between investigation locations, and there may be special conditions pertaining to the site which have not been revealed by the investigation and which have not therefore been taken into account in the document. Where variations exist on site, additional studies and actions may be required. Tectonic’s opinions are based upon information that existed at the time that the work was performed. The passage of time, man-made or natural events, may alter the site conditions. It is understood that the Services undertaken allowed Tectonic to form an opinion of the actual conditions of the site at the time the site was visited and cannot be used to assess the effect of any subsequent changes in the quality of the site, or its surroundings, or any laws or regulations. Any assessments made in the preparation of this document are based on the conditions indicated from published sources and the findings of the investigation described. Actual subsurface conditions may differ from those indicated in the document (e.g. between boreholes or test pits). No warranty is included, either express or implied, that the actual conditions will conform exactly to the assessments contained in this document. Where data supplied by the client or other external sources, including previous site investigation data, have been used, it has been assumed that the information is correct unless otherwise stated. No responsibility is accepted by Tectonic for incomplete or inaccurate data supplied by others. This document is provided for the sole use by the Client and its professional advisers. No responsibility whatsoever for the contents of this document will be accepted to any person other than the Client. Any use which a third party makes of this document, or any reliance on or decisions to be made based on it, is the responsibility of such third parties. Tectonic accepts no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this document. Rev 1 (March 2016)
Used in these records
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