Geotechnical Investigation and Site Classification, Northlakes Estate Stage 21

Transcription

1 Geotechnical Investigation and Site Classification, Northlakes Estate Stage 21 October 2009 North Lakes Pty Ltd Parsons Brinckerhoff Australia Pty Limited ABN A-PR_9366 Level Bolton Street NEWCASTLE NSW 2300 PO Box 1162 NEWCASTLE NSW 2300 Australia Telephone Facsimile newcastle@pb.com.au Certified to ISO 9001, ISO 14001, AS/NZS 4801

2 Revision Details Date Amended By A Original 27/10/09 Parsons Brinckerhoff Australia Pty Limited (PB) [2009]. Copyright in the drawings, information and data recorded in this document (the information) is the property of PB. This document and the information are solely for the use of the authorised recipient and this document may not be used, copied or reproduced in whole or part for any purpose other than that for which it was supplied by PB. PB makes no representation, undertakes no duty and accepts no responsibility to any third party who may use or rely upon this document or the information. Author: Glen Burton... Signed:... Reviewer: Stephen Flux... Signed:... Approved by: Glen Burton... Signed:... Date: 27/10/09... Distribution: North Lakes Pty Ltd (PDF)... Please note that when viewed electronically this document may contain pages that have been intentionally left blank. These blank pages may occur because in consideration of the environment and for your convenience, this document has been set up so that it can be printed correctly in double-sided format. \\AUNCLF\PROJ\N\NORTHLAKES\ A_NTH_LKS_ST_21_SITE\05_WRKPAPERS\WP\DRAFT\ A-PR_9366.DOCX

3 Geotechnical Investigation and Site Classification, Northlakes Estate Stage 21 Contents Page number 1. Introduction 1 2. Investigation method 3 3. Investigation results Site description Regional geology and subsurface conditions Fill Topsoil Residual soil Weathered rock Groundwater Laboratory results 6 4. Discussion and recommendations Site classifications Site preparation Excavations Filling Footing design and construction Drainage 9 5. Limitations 11 PARSONS BRINCKERHOFF A-PR_9366 Page i

4 Geotechnical Investigation and Site Classification, Northlakes Estate Stage 21 Contents (Continued) List of tables Page number Table 3.1 Typical subsurface profile 5 Table 3.2 Shrink/swell results 6 Table 4.1 Site classifications 7 Appendices Appendix A Figures Appendix B Engineering logs and explanatory notes Appendix C Laboratory certificates Appendix D Limitations of geotechnical site investigation Appendix E Reactive soil notes Page ii A-PR_9366 PARSONS BRINCKERHOFF

5 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Introduction At the request of North Lakes Pty Ltd, Parsons Brinckerhoff (PB) has completed a geotechnical site investigation of Stage 21 at Northlakes Estate, Cameron Park, New South Wales. At the time of the investigation, Stage 21 consisted of twenty six residential lots (2101 to 2126). The investigation was generally completed in accordance with our proposal (PB Ref: PP_9342, dated 17 September 2009) with the objective to assess subsurface conditions within the residential lots and assign site classifications in accordance with AS PB s civil engineers provided civil design drawings for the stages which were used to scope the site investigation. PARSONS BRINCKERHOFF A-PR_9366 Page 1

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7 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Investigation method Fieldwork for the investigation was carried out on 6 October 2009 and comprised the excavation of 12 test pits (TP2101 to TP2112). Test pits were initially located on lot boundaries to minimise potential disturbance to future footings with residential buildings. One of the test pits (TP2110) was moved off a lot boundary due to the placement of the site office and excavating equipment. The location of the test pits were recorded using a hand held GPS. The locations are shown on Figure 1 attached in Appendix A. A geotechnical engineer from PB supervised the test pit excavations, collected representative subsoil samples and prepared engineering logs of the subsurface conditions encountered. Pocket penetrometer tests were completed in clayey soils to assess the consistency. Description of the subsurface conditions was completed with reference to AS Geotechnical site investigations and PBs field manual for site investigation. Engineering test pit logs are attached in Appendix B along with explanatory notes that describe the terms and symbols used. The strength of bedrock was assessed by observation of excavation resistance in conjunction with inspection of fragments recovered from the test pits. Groundwater observations were made in the test pits both during and a short time after excavation prior to backfill. No long term groundwater monitoring was undertaken. Undisturbed (U50) samples were collected from selected test pits and sent to Valley Civilab, a NATA accredited laboratory, for shrink/swell analysis. The laboratory certificates are attached in Appendix C. PARSONS BRINCKERHOFF A-PR_9366 Page 3

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9 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Investigation results 3.1 Site description Stage 21 is located off Constitution Drive in Northlakes Estate, straddling Roads 28 (Shipley Street) and 32A (Hooghly Avenue) and to the south-east of Road 32 (Hooghly Avenue). At the time of the investigation, Stages 21 was still under construction. Partial clearing of the site had been completed for the associated works with mature trees still located throughout the residential lots. Slope gradients at the site range from 2 to 12 generally in a south-westerly direction. Drainage from the site runs off to a natural gully line to the south-east. 3.2 Regional geology and subsurface conditions The Newcastle Soil Landscape Series Sheet 9232 indicates that the site lies within the Warners Bay residual soil landscape. This unit comprises undulating to rolling low hills and rises on fine-grained sediments of the Newcastle Coal Measures in the Awaba Hills. The Newcastle 1:250,000 Geological Series Sheet SI 56-2 indicates that the site is underlain by the Newcastle Coal Measures of Permian age. This unit comprises interbedded conglomerate, sandstone, tuff, shale and coal. The typical subsurface profile encountered during the investigation program is summarised in Table 3.1. For a detailed description at specific locations, reference should be made to the engineering logs and explanatory notes attached in Appendix B. Table 3.1 Typical subsurface profile Material Fill 0.0 to 0.10 Topsoil 0.0 to 0.2 Residual soil to 1.00 Weathered rock Depth range encountered (m) Note 1: Topsoil assumed to be striped and replaced with shallow fill. The characteristics of the subsurface conditions are summarised below Fill Some filling on the site consisted of landscaping woodchips. Minor filling was present at the locations investigated to the west of Road 28 (Shipley Street) where gravelly SAND (SP) or GRAVEL (GP) was encountered to depths up to 0.10 m Topsoil Topsoil depths of 0.2 m are typical, with the material predominantly silty SAND (SM), brown to grey, fine grained with organic material. Moisture was typically assessed as dry during the investigation with loose to medium dense relative density. Low to medium plasticity grey CLAY (CL) was also identified within some of the test pits. PARSONS BRINCKERHOFF A-PR_9366 Page 5

10 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Residual soil Residual soil at the site typically comprises sandy/clayey SILT (ML) or sandy/silty CLAY (CL), low to medium plasticity, grey to brown with varying percentage of fine grained sand. Consistency was typically very stiff to hard with moisture contents at or less than the plastic limit Weathered rock Weathered rock was encountered in the test pits at depths between 0.10 m and 1.00 m, with bucket refusal of the backhoe typically occurring around 1.00 m on highly weathered siltstone and sandstone of medium strength at depths. Typically, the depth to bedrock is shallower (0.10 m to 0.60 m) along the western and eastern edges of the site. Excavation was readily achievable through extremely low to low strength material. Weathering of the rock resulted in interbedding of weathered rock and residual soil material Groundwater No groundwater was encountered within any of the test pits during the short period that they remained open. No long term monitoring was undertaken. Groundwater levels can be influenced by many factors including: Regional groundwater levels Local and regional drainage Geology Rainfall Changes in land use Groundwater extraction. 3.3 Laboratory results Undisturbed (U50) samples were sent to Valley Civilab for shrink/swell analysis. The results are summarised in Table 3.2 and certificates are attached in Appendix C. Table 3.2 Shrink/swell results Sample location Shrink/Swell I ss (%) TP TP TP TP TP Page A-PR_9366 PARSONS BRINCKERHOFF

11 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Discussion and recommendations 4.1 Site classifications In assessing site classification for the lots in this site, consideration has been given to subsurface conditions, soil reactivity, anticipated fill settlement, and slope stability. AS provides for the classification of lots based on the characteristic surface movement as follows: Surface Movement, y s (mm) Site Classification 0<y s 20 S 20<y s 40 M 40<y s 70 H 70<y s E The subject lots have been classified as detailed in Table 4.1. Table 4.1 Site classifications Lot Site Class Lot Site Class 2101 S 2114 M 2102 S 2115 M 2103 M 2116 M 2104 M 2117 M 2105 M 2118 M 2106 M 2119 S 2107 M 2120 S 2108 M 2121 S 2109 M 2122 S 2110 M 2123 S 2111 M 2124 S 2112 M 2125 M 2113 M 2126 M 4.2 Site preparation In general, all earthworks should be completed in accordance with AS3798 Guidelines on earthworks for commercial and residential developments. All topsoil, organic matter and any existing uncontrolled fill should be stripped from areas where engineered fill or slabs are to be placed. A typical stripping depth of 0.20 m should be allowed for the site. Areas to be filled should be proofed rolled under the inspection of a geotechnical engineer/engineering geologist and any soft or heaving materials removed. PARSONS BRINCKERHOFF A-PR_9366 Page 7

12 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Excavations If required and where practicable, excavated slopes should be benched in accordance with the NSW WorkCover: Code of Practice Excavation March Excavations within the topsoil, residual soils and extremely weathered bedrock should be achievable using conventional earthmoving equipment such as excavators, backhoes or bobcats. It is anticipated that excavation within the distinctly weathered bedrock should be feasible using hydraulic excavators with rock hammers. Excavation conditions were not investigated below backhoe refusal, which typically ranged from 0.40 m to 2.40 m deep. Temporary excavations through natural soils and extremely low to very low strength bedrock, up to a maximum depth of 1.5m, may be excavated near vertical provided that: they are barricaded when not in use they are not left open for more than 24 hours no surcharge loading is applied within 2.5m of the edge of the excavation no groundwater inflows are encountered they are not used for access by a worker Where the excavation is to be open for more than 24 hours or access is required for a worker or deeper excavations are required, the excavation batters should be regraded to no steeper than 1.5H in 1V, or supported by properly designed shoring. Any permanent excavations should be battered no steeper than 3H in 1V and vegetated to reduce erosion potential. If steeper batters are required they should be supported by properly engineered and constructed retaining walls with due consideration to surcharge loads and drainage conditions. The above recommendations should be confirmed by a geotechnical engineer once the profile is exposed. 4.4 Filling Prior to placement of fill, areas to be filled should be prepared as detailed in the Section 4.2. Placement of fill should be in maximum 300 mm (loose) layers. The full depth of each layer should be compacted to 95 % standard maximum dry density (SMDD) at ± 2 % of the standard optimum moisture content (SOMC). Each layer should be placed to minimum of Level 2 supervision in accordance with AS Level 1 supervision should be provided in areas to support high level footings with a relative compaction of 98 % SMDD achieved. All permanent fill slopes should be graded no steeper than 2H in 1V and should be protected from erosion. Alternatively, fill embankments may be retained with properly engineered and constructed retaining walls with due consideration to surcharge loads and drainage conditions. The depth of fill placed on individual lots should not exceed a nominal 1.5 m without prior approval by a geotechnical engineer/engineering geologist. Page A-PR_9366 PARSONS BRINCKERHOFF

13 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Footing design and construction In general, flexible structures such as brick veneer or clad frames are preferred for residential development on reactive clay sites. Footings should be designed by a practising structural engineer in accordance with AS for the classifications provided in Section 4.1. Strip/pad footings, raft slabs and pier and beam systems would be suitable footing types. Any future cut and fill earthworks may affect the site classifications provided in this report. We recommend that the site classifications be reassessed if excavations in excess of 0.4 m or filling in excess of 0.5 m thick are proposed. Footings should be excavated, cleaned out and poured with minimum delay. If footing excavations are to be left open for an extended period of time, a concrete blinding layer should be provided to protect the foundation material. Should any uncompacted fill or locally deep topsoil be encountered during footing excavation, these materials should be penetrated and the footings founded in accordance with the requirements of Section 6 of AS A geotechnical engineer should be consulted if these conditions are encountered. Where footing excavations are partially on rock, the whole footing should be taken to rock to achieve uniform bearing and foundation conditions. Alternatively structures may be articulated over changes in founding conditions, in accordance with AS Where footings are to be founded on rock, reclassification of the site and amendment to footing sizes may be appropriate, and both a geotechnical and structural engineer should be consulted prior to construction of the footing. 4.6 Drainage Site drainage should be installed to prevent ponding of surface water adjacent to structures. Surface water and roof runoff should be directed away from foundations and collected in the stormwater system. Where retaining walls are required, subsoil drainage should be provided and connected to the stormwater system. Surface water flows should be redirected from batter slopes by the use of dish drains. Classification of the subject lots has been assessed based on moisture variations caused by normal climatic and garden conditions. More severe moisture variations can be caused by other common, but controllable factors. Reactive soil notes included in Appendix E are intended as a summary to those provided in CSIRO A guide to Home Owners on Foundation Maintenance and Footing Performance and should be regarded as recommendations. Future owners should be advised of these maintenance procedures, as it is commonly accepted that most damage to residential type structures on reactive sites is due to poor site maintenance. PARSONS BRINCKERHOFF A-PR_9366 Page 9

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15 Geotechnical Investigation and Site Classification, Northlakes Estate Stage Limitations This report should be read in conjunction with the Limitations of Geotechnical Site Investigation statement attached in Appendix D, which provides important information regarding geotechnical investigation and assessment. Significant variation in subsurface conditions from those anticipated should be reported to this office for reassessment. ReferencesAustralian Standards AS 1289 Methods of testing soils for engineering purposes. Standards Australia Australian Standard. (1993). AS Geotechnical site investigations. Standards Australia. Australian Standard. (1996). AS Residential slabs and footings-construction. Standards Australia. Australian Standard. (2007). AS Guidelines on earthworks for commercial and residential developments. Standards Australia. WorkCover Authority of New South Wales Code of Practice - Excavation 2000 Australian Standard. (2007). AS Guidelines on earthworks for commercial and residential developments. Standards Australia. Newcastle Soil Landscape Series Sheet 9232 Newcastle 1:250,000 Geological Series Sheet SI 56-2 PARSONS BRINCKERHOFF A-PR_9366 Page 11

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17 Appendix A Figures

18 Client: Project: Location: North Lakes Pty Ltd Geotechnical Investigation and Site Classification Cameron Park, NSW LEGEND APPROXIMATE TEST PIT LOCATION. STAGE 21 BOUNDARY Full Size 1:1000 A3 SCALE (m) Stage 21 Test Pit Location Plan Figure 1

19 Appendix B Engineering logs and explanatory notes

20 Explanatory Notes - Soil Description In engineering terms soil includes every type of uncemented or partially cemented inorganic material found in the ground. In practice, if the material can be remoulded by hand in its field condition or in water it is described as a soil. The dominant soil constituent is given in capital letters, with secondary textures in lower case. The dominant feature is assessed from the Unified Soil Classification system and a soil symbol is used to define a soil layer. METHOD Method AS BH CT EE EX HA HQ JET NMLC NQ PT RAB RB RT TC V WB DT WATER Description Auger Screwing Backhoe Cable Tool Rig Existing Excavation/Cutting Excavator Hand Auger Diamond Core-63mm Jetting Diamond Core 52mm Diamond Core 47mm Push Tube Rotary Air Blast Rotary Blade Rotary Tricone Bit Auger TC Bit Auger V Bit Washbore Diatube Water level at date shown Partial water loss MOISTURE CONDITION Dry Moist Wet - Cohesive soils are friable or powdery Cohesionless soil grains are free-running - Soil feels cool, darkened in colour Cohesive soils can be moulded Cohesionless soil grains tend to adhere - Cohesive soils usually weakened Free water forms on hands when handling For cohesive soils the following codes may also be used: MC>PL MC~PL MC<PL PLASTICITY Moisture Content greater than the Plastic Limit. Moisture Content near the Plastic Limit. Moisture Content less than the Plastic Limit. The potential for soil to undergo change in volume with moisture change is assessed from its degree of plasticity. The classification of the degree of plasticity in terms of the Liquid Limit (LL) is as follows: Description of Plasticity LL (%) Low <35 Medium 35 to 50 High >50 Water inflow Complete water loss COHESIVE SOILS - CONSISTENCY NFGWO: The observation of groundwater, whether present or not, was not possible due to drilling water, surface seepage or cave in of the borehole/test pit. NFGWE: The borehole/test pit was dry soon after excavation. Inflow may have been observed had the borehole/test pit been left open for a longer period. SAMPLING The consistency of a cohesive soil is defined by descriptive terminology such as very soft, soft, firm, stiff, very stiff and hard. These terms are assessed by the shear strength of the soil as observed visually, by hand penetrometer values and by resistance to deformation to hand moulding. A Hand Penetrometer may be used in the field or the laboratory to provide an approximate assessment of the unconfined compressive strength (UCS) of cohesive soils. The undrained shear strength of cohesive soils is approximately half the UCS. The values are recorded in kpa as follows: Sample B D Jar SPT U50 U75 Description Bulk Disturbed Sample Disturbed Sample Jar Sample Standard Penetration Test Undisturbed Sample 50mm Undisturbed Sample 75mm Strength Symbol Undrained Shear Strength, C u (kpa) Very Soft VS < 12 Soft S 12 to 25 Firm F 25 to 50 Stiff St 50 to 100 Very Stiff VSt 100 to 200 Hard H > 200 UNIFIED SOIL CLASSIFICATION The appropriate symbols are selected on the result of visual examination, field tests and available laboratory tests, such as, sieve analysis, liquid limit and plasticity index. USC Symbol GW GP GM GC SW SP SM SC ML CL OL MH CH OH Pt Description Well graded gravel Poorly graded gravel Silty gravel Clayey gravel Well graded sand Poorly graded sand Silty sand Clayey sand Silt of low plasticity Clay of low plasticity Organic soil of low plasticity Silt of high plasticity Clay of high plasticity Organic soil of high plasticity Peaty Soil COHESIONLESS SOILS - RELATIVE DENSITY Relative density terms such as very loose, loose, medium, dense and very dense are used to describe silty and sandy material, and these are usually based on resistance to drilling penetration or the Standard Penetration Test (SPT) N values. Other condition terms, such as friable, powdery or crumbly may also be used. Term Symbol Density Index N Value (blows/0.3 m) Very Loose VL 0 to 15 0 to 4 Loose L 15 to 35 4 to 10 Medium Dense MD 35 to to 30 Dense D 65 to to 50 Very Dense VD >85 >50 COHESIONLESS SOILS PARTICLE SIZE DESCRIPTIVE TERMS Name Subdivision Size Boulders Cobbles >200 mm 63 mm to 200 mm Gravel coarse medium fine 20 mm to 63 mm 6 mm to 20 mm 2.36 mm to 6 mm C:\Webs\ausydg\BP20_TechGuidelines\20.5 Geotechnical\stdnotes\Geotech Explan. Notes - brief version.doc 30/09/02 1 Sand coarse medium fine 600 µm to 2.36 mm 200 µm to 600 µm 75 µm to 200 µm

21 Rock Description The rock is described with strength and weathering symbols as shown below. Other features such as bedding and dip angle are given. METHOD Refer soil description sheet WATER Refer soil description sheet ROCK QUALITY The fracture spacing is shown where applicable and the Rock Quality Designation (RQD) or Total Core Recovery (TCR) is given where: TCR (%) = length of core recovered length of core run ROCK STRENGTH Rock strength is described using AS1726 and ISRM - Commission on Standardisation of Laboratory and Field Tests, "Suggested method of determining the Uniaxial Compressive Strength of Rock materials and the Point Load Index", as follows: Term Symbol Point Load Index Is (50) (MPa) Extremely Low EL <0.03 Very Low VL 0.03 to 0.1 Low L 0.1 to 0.3 Medium M 0.3 to 1 High H 1 to 3 Very High VH 3 to 10 Extremely High EH >10 RQD (%) = Sum of Axial lengths of core > 100mm long length of core run Diametral Point Load Index test Axial Point Load Index test ROCK MATERIAL WEATHERING Rock weathering is described using the abbreviations and definitions used in AS1726. AS1726 suggests the term Distinctly Weathered (DW) to cover the range of substance weathering conditions between (but not including) XW and SW. For projects where it is not practical to delineate between HW and MW or it is deemed that there is no advantage in making such a distinction, DW may be used with the definition given in AS1726. Symbol Term Definition RS Residual Soil Soil definition on extremely weathered rock; the mass structure and substance are no longer evident; there is a large change in volume but the soil has not been significantly transported XW HW MW SW DW Extremely Weathered Highly Weathered Distinctly Weathered (see AS1726 Definition below) Moderately Weathered Slightly Weathered Rock is weathered to such an extent that it has soil properties, ie. It either disintegrates or can be remoulded in water The rock substance is affected by weathering to the extent that limonite staining or bleaching affects the whole rock substance and other signs of chemical or physical decomposition are evident. Porosity and strength is usually decreased compared to the fresh rock. The colour and strength of the fresh rock is no longer recognisable. The whole of the rock substance is discoloured, usually by iron staining or bleaching, to the extent that the colour of the fresh rock is no longer recognisable Rock is slightly discoloured but shows little or no change of strength from fresh rock FR Fresh Rock shows no sign of decomposition or staining Distinctly Weathered: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to the deposition of weathering products in pores. (AS1726) DEFECT SPACING/BEDDING THICKNESS Measured at right angles to defects of same set or bedding. Term Defect Spacing Bedding Extremely closely spaced <6 mm 6 to 20 mm Thinly Laminated Laminated Very closely spaced 20 to 60 mm Very Thin Closely spaced 0.06 to 0.2 m Thin Moderately widely spaced 0.2 to 0.6 m Medium Widely spaced 0.6 to 2 m Thick Very widely spaced >2 m Very Thick DEFECT DESCRIPTION Type: B BP F C J SZ CZ DB Planarity: P Planar Ir Irregular St Stepped U Undulating Coating or Infill: Clean Stain Veneer Coating Definition: Bedding Bedding Parting Fault Cleavage Joint Shear Zone Crushed Zone Drill Break Roughness: R Rough S Smooth Sl Slickensides Po Polished Description No visible coating or infilling No visible coating or infilling but surfaces are discoloured by mineral staining A visible coating or infilling of soil or mineral substance but usually unable to be measured (<1mm). If discontinuous over the plane, patchy veneer A visible coating or infilling of soil or mineral substance, >1mm thick. Describe composition and thickness The inclinations of defects are measured from perpendicular to the core axis. C:\Webs\ausydg\BP20_TechGuidelines\20.5 Geotechnical\stdnotes\Geotech Explan. Notes - brief version.doc 30/09/02 2

22 Graphic Symbols for Soil and Rock Graphic symbols used on borehole and test pit reports for soil and rock are as follows. Combinations of these symbols may be used to indicate mixed materials such as clayey sand. C:\Webs\ausydg\BP20_TechGuidelines\20.5 Geotechnical\stdnotes\Geotech Explan. Notes - brief version.doc 30/09/02 Page 3

23 TEST PIT ENGINEERING LOG TEST PIT NO. TP2101 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 6/10/09 6/10/09 MJH SF Excavation Method: WATER N F G W E Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (SM) SOIL/ROCK MATERIAL FIELD DESCRIPTION TOPSOIL: Silty SAND, fine grained, brown, with root fibres Surface RL: Co-ords: Field Material Description MOISTURE D RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA HAND PENETROMETER (kpa) STRUCTURE AND ADDITIONAL OBSERVATIONS TOPSOIL 0.20 (ML) Sandy SILT, grey, fine grained sand MC<PL RESIDUAL SOIL 0.35 (CL) Silty CLAY, low plasticity, grey, interbedded with extremely weathered, extremely low strength siltstone Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ SILTSTONE, grey to off-white, distinctly weathered, low to medium strength END OF TEST PIT AT 1.15 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. WEATHERED ROCK Bucket refusal on medium strength siltstone

24 TEST PIT ENGINEERING LOG TEST PIT NO. TP2102 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 6/10/09 6/10/09 MJH SF Excavation Method: WATER N F Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (SC) TOPSOIL: Clayey SAND, fine to medium grained, brown, medium plasticity clay with root fibres 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description MOISTURE D RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA HAND PENETROMETER (kpa) STRUCTURE AND ADDITIONAL OBSERVATIONS TOPSOIL G W E 0.10 (ML) Sandy SILT, grey, fine grained sand, with sandstone boulders up to 300mm and roots MC<PL RESIDUAL SOIL 0.35 SANDSTONE, fine to medium grained, grey mottled orange to red, distinctly weathered, medium strength WEATHERED ROCK Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/09 1 END OF TEST PIT AT 0.60 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. Bucket refusal on medium to high strength sandstone

25 TEST PIT ENGINEERING LOG TEST PIT NO. TP2103 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 6/10/09 6/10/09 MJH SF Excavation Method: 1 WATER N F Test Pit Information RL(m) 2 DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL FILL: Woodchips 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description MOISTURE RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA HAND PENETROMETER (kpa) FILL STRUCTURE AND ADDITIONAL OBSERVATIONS G W E 0.10 (ML) Sandy SILT, grey, fine grained sand, with tree roots MC<PL RESIDUAL SOIL 0.45 SANDSTONE, grey, extremely weathered, low strength WEATHERED ROCK Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/09 1 END OF TEST PIT AT 0.60 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. Bucket refusal on medium strength sandstone

26 Client: Project: Test Pit Location: Project Number: Excavation Method: WATER N F Test Pit Information RL(m) DEPTH(m) FIELD TEST 5 TEST PIT ENGINEERING LOG North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Backhoe with 300mm bucket SAMPLE GRAPHIC LOG 6 USC SYMBOL FILL: Woodchips 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description 8 MOISTURE VS S FST 9 RELATIVE DENSITY /CONSISTENCY FB VL L MD D VD VST H Date Commenced: Date Completed: Recorded By: Log Checked By: E N MGA 10 HAND PENETROMETER (kpa) TOPSOIL TEST PIT NO. TP SHEET 1 OF 1 5/10/09 5/10/09 MJH SF STRUCTURE AND ADDITIONAL OBSERVATIONS G W E (SM) (CL) TOPSOIL: Silty SAND, fine to medium grained, brown, with root fibres Sandy CLAY, medium plasticity, brown, fine grained sand, D RESIDUAL SOIL Section of test pit appears to have some fill. Possibly associated with drainage line excavation of lot boundary. Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ (CL) Sandy CLAY, medium plasticity, brown, fine grained sand, trace tree roots SILTSTONE, grey, highly weathered, low to medium strength, thinly laminated END OF TEST PIT AT 0.90 m MC<PL >600 >600 >600 This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. WEATHERED ROCK Bucket refusal on medium strength siltstone

27 TEST PIT ENGINEERING LOG TEST PIT NO. TP2105 SHEET 1 OF 2 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: 1 WATER N F G W E Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (SM) TOPSOIL: Silty SAND, fine to medium grained, brown, low plasticity clay and with root fibres 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description 8 9 MOISTURE D RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA 10 HAND PENETROMETER (kpa) TOPSOIL 11 STRUCTURE AND ADDITIONAL OBSERVATIONS 0.20 (CH) Silty CLAY, medium to high plasticity, brown mottled orange, trace root fibres MC<PL >600 >600 >600 RESIDUAL SOIL Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ U50 (ML) (ML) Clayey SILT, grey to brown mottled orange, low to medium plasticity clay Clayey SILT, grey to brown mottled orange, low to medium plasticity clay, interbedded with extremely weathered, extremely low strength Siltstone This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. MC~PL MC<PL WEATHERED ROCK

28 TEST PIT ENGINEERING LOG TEST PIT NO. TP2105 SHEET 2 OF 2 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: 1 WATER Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (ML) Clayey SILT, grey to brown mottled orange, low to medium plasticity clay, interbedded with extremely weathered, extremely low strength Siltstone (continued) 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description MOISTURE MC<PL RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA HAND PENETROMETER (kpa) 11 STRUCTURE AND ADDITIONAL OBSERVATIONS 2.20 SILTSTONE, brown to grey mottled orange, highly weathered, low strength END OF TEST PIT AT 2.40 m Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/09 3 This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. Bucket refusal on low to medium strength siltstone

29 TEST PIT ENGINEERING LOG TEST PIT NO. TP2106 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: 1 WATER N F Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (ML) TOPSOIL: Sandy SILT, brown, fine grained sand, with root fibres 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description MOISTURE D RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA HAND PENETROMETER (kpa) STRUCTURE AND ADDITIONAL OBSERVATIONS TOPSOIL G W E 0.10 SILTSTONE, grey to orange, extremely weathered, low strength WEATHERED ROCK 0.30 As above but medium to high strength END OF TEST PIT AT 0.40 m Bucket refusal on high strength siltstone Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/09 1 This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes.

30 TEST PIT ENGINEERING LOG TEST PIT NO. TP2107 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: 1 WATER N F G Test Pit Information RL(m) DEPTH(m) Backhoe with 300mm bucket FIELD TEST SAMPLE GRAPHIC LOG USC SYMBOL (SC) SOIL/ROCK MATERIAL FIELD DESCRIPTION TOPSOIL: Clayey SAND, fine to medium grained, brown, low to medium plasticity clay Surface RL: Co-ords: Field Material Description MOISTURE M FB VL L MD VS S FST 9 RELATIVE DENSITY /CONSISTENCY D VD VST H E N MGA 10 HAND PENETROMETER (kpa) TOPSOIL 11 STRUCTURE AND ADDITIONAL OBSERVATIONS W E 0.15 (SC) Clayey SAND, fine to medium grained, grey to orange, with Sandstone boulders up to 400mm, fine to medium grained, distinctly weathered, medium strength, with tree roots D RESIDUAL SOIL Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ U50 (CL) Silty CLAY, medium plasticity, brown to grey, with fine grained sand SILTSTONE, grey, extremely weathered, low strength END OF TEST PIT AT 1.30 m MC<PL >600 >600 >600 This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. WEATHERED ROCK Bucket refusal on low to medium strength siltstone

31 TEST PIT ENGINEERING LOG TEST PIT NO. TP2108 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: 1 WATER N F G Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (CL) TOPSOIL: Sandy CLAY, low plasticity, brown, fine grained sand, with silt and root fibres 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description 8 MOISTURE MC<PL FB VL L MD VS S FST 9 RELATIVE DENSITY /CONSISTENCY D VD VST H E N MGA 10 HAND PENETROMETER (kpa) TOPSOIL 11 STRUCTURE AND ADDITIONAL OBSERVATIONS W E 0.15 (CL) Sandy CLAY, low plasticity, brown mottled orange, fine grained sand RESIDUAL SOIL 0.45 (CL) As above but off white mottled brown Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ SILTSTONE, grey, extremely weathered, low to medium strength END OF TEST PIT AT 1.00 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. WEATHERED ROCK Bucket refusal on medium strength siltstone

32 TEST PIT ENGINEERING LOG TEST PIT NO. TP2109 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: WATER N F G W E Test Pit Information 1 2 RL(m) DEPTH(m) 3 FIELD TEST Backhoe with 300mm bucket 4 SAMPLE 5 GRAPHIC LOG 6 USC SYMBOL (ML) 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION TOPSOIL: Clayey SILT, brown, low plasticity clay, with root fibres Surface RL: Co-ords: Field Material Description 8 MOISTURE D 9 RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H E N MGA 10 HAND PENETROMETER (kpa) TOPSOIL 11 STRUCTURE AND ADDITIONAL OBSERVATIONS (CL) (CL) Silty CLAY, medium plasticity, brown trace root fibres Silty CLAY, low to medium plasticity, orange with sand fine grained, trace root fibres MC~PL MC<PL RESIDUAL SOIL Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ U50 (CL) Silty CLAY, low plasticity, grey mottled brown SILTSTONE, grey to brown, highly weathered, low to medium strength END OF TEST PIT AT 1.00 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes WEATHERED ROCK Bucket refusal on medium strength siltstone

33 TEST PIT ENGINEERING LOG TEST PIT NO. TP2110 SHEET 1 OF 1 Client: Project: Test Pit Location: Project Number: North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Date Commenced: Date Completed: Recorded By: Log Checked By: 5/10/09 5/10/09 MJH SF Excavation Method: 1 WATER N F Test Pit Information RL(m) DEPTH(m) FIELD TEST Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (SP) FILL: Gravelly SAND, fine to medium grained, brown, fine to coarse, sub-angular gravel 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description 8 MOISTURE D VS S FST 9 RELATIVE DENSITY /CONSISTENCY FB VL L MD D VD VST H E N MGA HAND PENETROMETER (kpa) FILL STRUCTURE AND ADDITIONAL OBSERVATIONS G W E 0.10 SANDSTONE, fine to medium grained, yellow to white, highly weathered, very low to low strength WEATHERED ROCK Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/09 1 END OF TEST PIT AT 0.50 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. Bucket refusal on medium strength sandstone

34 Client: Project: Test Pit Location: Project Number: Excavation Method: 1 WATER N F G W E Test Pit Information RL(m) DEPTH(m) FIELD TEST North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Backhoe with 300mm bucket SAMPLE GRAPHIC LOG USC SYMBOL (GP) (ML) TEST PIT ENGINEERING LOG SOIL/ROCK MATERIAL FIELD DESCRIPTION FILL: Gravel, fine to medium, grey, sub-angular Sandy SILT, brown, fine grained sand, trace root fibres Surface RL: Co-ords: Field Material Description MOISTURE D-M RELATIVE DENSITY /CONSISTENCY FB VL L MD VS S FST D VD VST H Date Commenced: Date Completed: Recorded By: Log Checked By: FILL RESIDUAL SOIL 5/10/09 5/10/09 MJH SF E N MGA 10 HAND PENETROMETER (kpa) TEST PIT NO. TP SHEET 1 OF 1 STRUCTURE AND ADDITIONAL OBSERVATIONS 0.25 (CL) Silty CLAY, medium plasticity, brown, with large root fibres MC<PL U50 Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ SANDSTONE, fine, white mottled orange interbedded with siltstone, extremely weathered, low strength END OF TEST PIT AT 0.90 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes. WEATHERED ROCK Bucket refusal on low to medium strength sandstone

35 Client: Project: Test Pit Location: Project Number: Excavation Method: WATER N F G W E Test Pit Information RL(m) 0.02 DEPTH(m) FIELD TEST North Lakes Pty Ltd Geotechnical lnvestigation and Site Classification Stage 21, Northlakes Estate A Backhoe with 300mm bucket SAMPLE GRAPHIC LOG 6 USC SYMBOL (SP) (SC) TEST PIT ENGINEERING LOG FILL: Gravelly SAND, fine to medium, yellow, fine to medium gravel, grey Clayey SAND, fine to medium, brown, low plasticity clay trace root fibres 7 SOIL/ROCK MATERIAL FIELD DESCRIPTION Surface RL: Co-ords: Field Material Description 8 MOISTURE W M VS S FST 9 RELATIVE DENSITY /CONSISTENCY FB VL L MD D VD VST H Date Commenced: Date Completed: Recorded By: Log Checked By: E N MGA 10 HAND PENETROMETER (kpa) FILL RESIDUAL SOIL TEST PIT NO. TP SHEET 1 OF 1 5/10/09 5/10/09 MJH SF STRUCTURE AND ADDITIONAL OBSERVATIONS 0.30 (CH) Silty CLAY, medium to high plasticity, grey to brown MC~PL Parsons Brinckerhoff Australia Pty Ltd. Version 5.1 ENGINEERING TEST PIT LOG STAGE 21 GEOTECHNICAL INVESTIGATION.GPJ YH2006.GDT 27/10/ U50 SILTSTONE, off white, slightly weathered, medium to high strength END OF TEST PIT AT 0.90 m This test pit log should be read in conjunction with Parsons Brinckerhoff's accompanying standard notes Large tree root WEATHERED ROCK Bucket refusal on medium to high strength siltstone

36 Appendix C Laboratory certificates

37

38

39

40

41

42 Appendix D Limitations of geotechnical site investigation

43 Legal Standard Work Practice Limitations of Geotechnical Site Investigation SP-LGL-2002 Rev: A Scope of services This geotechnical site assessment report (the report) has been prepared in accordance with the scope of services set out in the contract, or as otherwise agreed, between the client and PB (scope of services). In some circumstances the scope of services may have been limited by a range of factors such as time, budget, access and/or site disturbance constraints. Reliance on data In preparing the report, PB has relied upon data, surveys, analyses, designs, plans and other information provided by the client and other individuals and organisations, most of which are referred to in the report (the data). Except as otherwise stated in the report, PB has not verified the accuracy or completeness of the data. To the extent that the statements, opinions, facts, information, conclusions and/or recommendations in the report (conclusions) are based in whole or part on the data, those conclusions are contingent upon the accuracy and completeness of the data. PB will not be liable in relation to incorrect conclusions should any data, information or condition be incorrect or have been concealed, withheld, misrepresented or otherwise not fully disclosed to PB. Geotechnical investigation Geotechnical engineering is based extensively on judgment and opinion. It is far less exact than other engineering disciplines. Geotechnical engineering reports are prepared to meet the specific needs of individuals. A report prepared for a consulting civil engineer may not be adequate for a construction contractor or even some other consulting civil engineer. This report was prepared expressly for the client and expressly for purposes indicated by the client or his representative. Use by any other persons for any purpose, or by the client for a different purpose, might result in problems. The client should not use this report for other than its intended purpose without seeking additional geotechnical advice. This geotechnical report is based on project-specific factors This geotechnical engineering report is based on a subsurface investigation which was designed for project-specification factors, including the nature of any development, its size and configuration, the location of any development on the site and its orientation, and the location of access roads and parking areas. Unless further geotechnical advice is obtained this geotechnical engineering report cannot be used: when the nature of any proposed development is changed when the size, configuration location or orientation of any proposed development is modified. This geotechnical engineering report cannot be applied to an adjacent site. Parsons Brinckerhoff Australia Pty Limited ABN Prepared: Approved: Legal Counsel Page 1 of 3

44 Legal Standard Work Practice Limitations of Geotechnical Site Investigation SP-LGL-2002 Rev: A The limitations of site investigation In making an assessment of a site from a limited number of boreholes or test pits there is the possibility that variations may occur between test locations. Site exploration identifies specific subsurface conditions only at those points from which samples have been taken. The risk that variations will not be detected can be reduced by increasing the frequency of test locations; however this often does not result in any overall cost savings for the project. The investigation program undertaken is a professional estimate of the scope of investigation required to provide a general profile of the subsurface conditions. The data derived from the site investigation program and subsequent laboratory testing are extrapolated across the site to form an inferred geological model and an engineering opinion is rendered about overall subsurface conditions and their likely behaviour with regard to the proposed development. Despite investigation the actual conditions at the site might differ from those inferred to exist, since no subsurface exploration program, no matter how comprehensive, can reveal all subsurface details and anomalies. The borehole logs are the subjective interpretation of subsurface conditions at a particular location, made by trained personnel. The interpretation may be limited by the method of investigation, and can not always be definitive. For example, inspection of an excavation or test pit allows a greater area of the subsurface profile to be inspected than borehole investigation, however, such methods are limited by depth and site disturbance restrictions. In borehole investigation, the actual interface between materials may be more gradual or abrupt than a report indicates. Subsurface conditions are time dependent Subsurface conditions may be modified by changing natural forces or man-made influences. A geotechnical engineering report is based on conditions which existed at the time of subsurface exploration. Construction operations at or adjacent to the site, and natural events such as floods, or groundwater fluctuations, may also affect subsurface conditions, and thus the continuing adequacy of a geotechnical report. The geotechnical engineer should be kept appraised of any such events, and should be consulted to determine if additional tests are necessary. Avoid misinterpretation A geotechnical engineer should be retained to work with other appropriate design professionals explaining relevant geotechnical findings and in reviewing the adequacy of their plans and specifications relative to geotechnical issues. Bore/profile logs should not be separated from the engineering report Final bore/profile logs are developed by geotechnical engineers based upon their interpretation of field logs and laboratory evaluation of field samples. Customarily, only the final bore/profile logs are included in geotechnical engineering reports. These logs should not under any circumstances be redrawn for inclusion in architectural or other design drawings. To minimise the likelihood of bore/profile log misinterpretation, contractors should be given access to the complete geotechnical engineering report prepared or authorised for their use. Providing the best available information to contractors helps prevent costly construction problems. For further information on this matter reference should be made to Guidelines for the Provision of Geotechnical Information in Construction Contracts published by the Institution of Engineers Australia, National Headquarters, Canberra Geotechnical involvement during construction During construction, excavation is frequently undertaken which exposes the actual subsurface conditions. For this reason geotechnical consultants should be retained through the construction stage, to identify variations if they are exposed and to conduct additional tests which may be required and to deal quickly with geotechnical problems if they arise. Parsons Brinckerhoff Australia Pty Limited ABN Prepared: Approved: Legal Counsel Page 2 of 3

45 Legal Standard Work Practice Limitations of Geotechnical Site Investigation SP-LGL-2002 Rev: A Report for benefit of client The report has been prepared for the benefit of the client and no other party. PB assumes no responsibility and will not be liable to any other person or organisation for or in relation to any matter dealt with or conclusions expressed in the report, or for any loss or damage suffered by any other person or organisation arising from matters dealt with or conclusions expressed in the report (including without limitation matters arising from any negligent act or omission of PB or for any loss or damage suffered by any other party relying upon the matters dealt with or conclusions expressed in the report). Other parties should not rely upon the report or the accuracy or completeness of any conclusions and should make their own enquiries and obtain independent advice in relation to such matters. Other limitations PB will not be liable to update or revise the report to take into account any events or emergent circumstances or facts occurring or becoming apparent after the date of the report. Amendment details Revision Details Date By A Original 18/07/08 M Jenkins Parsons Brinckerhoff Australia Pty Limited ABN Prepared: Approved: Legal Counsel Page 3 of 3

46 Appendix E Reactive soil notes

47 Reactive Soils - General Design Precautions These procedures generally apply to masonry residential buildings founded on reactive clay soils. Such soils are prone to shrink/swell movements due to moisture variations (either by natural or artificial causes). It must be accepted that some degree of structural cracking is likely for structures founded on these soils. The basic design philosophy is to minimise any cracking and provide a serviceable structure. It is thus a compromise between economy and performance. The following procedures are supplementary to the foundation recommendations given in the attached report. All surface water runoff must be directed away from the building by appropriate grading in order to prevent ponding near foundations. Site drainage should form part of the building contract. Peripheral pathways, with impermeable underliner, should be provided around the building to improve site drainage and assist in the stabilisation of moisture conditions near foundations. All brickwork should be suitably articulated into discrete units to accommodate the expected movements. Brickwork over doors and windows should be avoided. Internal and external walls should be arranged along straight lines, where possible. All house drains and water pipes should be provided with sufficient flexibility to accommodate the expected differential movements (between foundation and uncovered outside area) at the level of the service. The extension of services through slabs should be avoided where possible in order to prevent hidden leaks under the slab area. Most plumbing fixtures can be arranged to exit through outside walls. Septic systems should be located so as not to influence the house or neighbouring foundations. Subgrades beneath elevated and well ventilated floors should be covered with an impermeable liner (with protective soil blanket) to minimise excessive desiccation. In addition, certain other site management precautions must be adhered to during the life of the structure. These precautions generally relate to the control of abnormal moisture variations due to the effects of drainage and vegetation. Recommendations on site management precautions are contained in the following section. Reactive Soil Notes Page 1 of 2

48 Reactive Soils - Site Management Precautions These precautions are considered supplementary to any structural and/or foundation design measures for the subject building, and are intended for distribution to the prospective house owner. Reactive clays are prone to heave/shrink movements with changes in soil moisture content due to natural or artificial means. The basic design philosophy employed for the dwelling is to provide a foundation/superstructure adequate to accommodate ground movements due to extreme seasonal moisture changes only. The possibility of other abnormal and/or localised moisture changes (the cause of most housing distress) has been assumed to be controlled by the following site management procedures. Leaking plumbing or blocked drains should be repaired promptly and site grading maintained to prevent ponding near foundations. Garden watering, particularly by fixed systems, should be controlled to avoid over-watering. Proper garden maintenance should produce year round uniform moisture conditions. Trees and some shrubs can cause a substantial drying and shrinking of reactive clays, additional to that experienced in a drought or a long dry spell. This effect is most likely to result in damage when added to the drying effects from a drought or a long dry spell. Trees should be planted at a substantial distance from the house. The distance depends upon the species and soil conditions, but generally a distance equal to 75% of the mature height is a minimum. Problems during a drought can be minimised by extensive pruning (thus reducing water demand) and/or providing trees with adequate water. Frequent moderate watering during dry periods should minimise the risk of the tree extracting excessive moisture from beneath the foundation of the house. This action should also be immediately undertaken by the owner if brickwork cracking due to tree drying is noticed. Most reactive clay failures can be minimised by controlling the combined drying effects of trees and drought. The owner should appreciate that on reactive clays it is virtually impossible to design an economic foundation system that will totally prevent movement. Some minor aesthetic cracking, while undesirable, is likely to occur in a significant proportion of houses. In addition some minor problems should be expected with jamming of windows and doors especially during the settling period or following a major drought and any repairs should be regarded as part of normal house maintenance. Even significant masonry cracking with widths over 3 mm usually has no influence on the function of the wall and only presents an aesthetic problem. Just as it is difficult to design an immovable footing system, it is almost impossible to provide remedial measures that will prevent further movement if distress does occur. Consequently, extreme remedial measures should not be undertaken for minor problems, without further engineering advice. Reference should be made to Appendix A of AS "Residential Slabs and Footings" and CSIRO "A Guide to Home Owners on Foundation Maintenance and Footing Performance" for more detailed recommendations regarding Design and Site management precautions. Reactive Soil Notes Page 2 of 2