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CIVIL HYDRAULICS STRUCTURAL GEOTECHNICAL FORENSIC DILAPIDATION PROJECT MANAGEMENT - Shop 3A, 1 Puckle Street Moonee Ponds, VIC 3039 - 23/ 94-98 Beamish Street, Campsie NSW 2194 www.fusionengineering.com.au 1800 787 750 info@fusionengineering.com.au

GEOTECHNICAL INVESTIGATION REPORT Geotechnical Site Investigation Report DATE: 18.11.2017 JOB NUMBER: 2017-2384: Revision 1 SITE ADDRESS: 510-516 Pacific Hwy, Mt Colah CLIENT: MOUNT COLAH DEVELOPMENT PTY LTD SITE CLASSIFICATION: CLASS P – M WIND RATING: N2

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1. Introduction Fusion Engineering Services has been engaged by the client to conduct a geotechnical site investigation at 510-516 Pacific Hwy, Mt Colah with the objective to determine the subsurface ground condition in order to classify under AS 2870-2011 and recommend suitable foundation types and other geotechnical constraints for proposed development. The proposed development involves the demolition of all existing dwelling and the construction of a Double‐store s residential building with a one‐le el basement car parking facility. This report presents and interprets the findings of the geotechnical investigation carried out on the 18th November 2017 at the subject site, known as number 510-516 Pacific Hwy, Mt Colah . With the site constraints, the fieldwork was carried out by using a track mounted drilling rig with four boreholes were drilled by tungsten Carbide drilling bit Auger refusal to provide the following information: • Method of investigation, • Site description, including surface and su ‐surfa e conditions, • Site plan indicating borehole locations and footprint of the proposed roads and buildings within the development, • Recommendations on the excavation conditions and temporary slope batters, • Recommendations on vibration control and management, • Provision of earth pressure parameters for design of retaining structures, • Recommendations on footings and serviceability bearing pressures, 2. Available Information At the time of writing this report, a set of architectural drawings from the client as listed below, by Studio Make Made referenced Project No. Arch 16-8 was provided to us and also available previous Geotechnical investigation done by Fusion Engineering 3. Geology Reference to the 1:250,000 scales Geological Series Map of the Sydney indicates that the subject site is underlain by Mittagong formation dating back to the Triassic Period.

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4. Fieldwork Fieldwork for the geotechnical investigation was carried on the 18th November 23, 2017 and comprised the following works: • A detailed alk‐o er inspection of the site and surrounding environment capture any significant geological features. • Drilling of four (4) boreholes, BH01 to BH04 using a drilling rig mounted with TC bit attached to a solid flight augerto a total depth of 3.5m (BH01) 4.5m (BH02), 1.6m (BH03 and BH04) respectively below existing ground level. The soil / rock encountered during drilling was visually classified to AS 1726 • The approximate locations of the 2 boreholes are shown in Figure 2 and the Engineering Logs are presented in Appendix B Subsurface Conditions The results of the investigation indicate that the subsurface profile at the test locations comprises some fill and top soil, Silty Clay with some ironstone band and rock sandstone. Based on the information obtained from the boreholes, a geotechnical model has been developed, and is presented in Table 1, together with a summary of subsurface conditions at the borehole locations. For a detailed description of the subsurface conditions encountered at the borehole locations, refer to the Engineering Logs in Appendix A, In-situ testing (from previous investigation)

Testi g as arried out i a orda e ith Australia Sta dard AS , Methods of Testi g Soil for E gi eeri g Purposes a d i luded:

•Dynamic Cone penetration test (DCP) Test results are included on the logs of the bore

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Table 1: Summary of Subsurface Conditions and Inferred Geotechnical Model Unit Description Depth to Base Of Unit (m) Thickness Of Unit (m) Remarks A Grey, silty Clay with some Gravel and Sandy gravelly Clay(fill) 0.3 (BH01, BH02) 0.6 (BH03, BH04) 0.3 0.6 Top Soil/Fill Fill material on BH03 &BH04 B Grey brown to red brown low to medium plasticity firm to stiff Silty Clay with traces of gravel 1(BH01& BH02) 0.8(BH03& BH04 ) 0.5-0.6 Residual Soil C Grey to red brown stiff to hard medium plasticity silty Clay iron stone gravel 2.2 (BH01) 2.8 (BH02) 1.6(BH03 & BH04 ) 0.4-0.7 BH 03 and BH04 refusal at 1.6m on sandstone (Residual Soil) D Grey, red brown to grey white very stiff to hard medium plasticity silty Clay iron stone gravel 3.5 (BH01) 4.5 (BH02) 0.4-0.7 BH 01 refusal at 3.5m on sandstone class V BH02 terminated on hard clay 5. Recommendation 5.1 Site Classification In accordance with AS2870-2 , Reside tial Sla s a d Footi gs - Constru tio a site lassifi atio of Co stru tio a lass P site lassifi atio is appropriate for this site due to existing house and services. In accordance with AS2870-2011 table 2.1, if assessed in accordance with engineering principles. The assessment shall consider the movement of the underlying soil from the condition of construction at construction to the long term equilibrium moisture conditions. The site may be reclassified as Medium Reactive soil (M) and estimated to have a characteristic surface movement 20 to 40 mm

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On the basis of the findings in this investigation, including visual-tactile identification of the soil profile o i ed ith this riter s lo al k o ledge a d e perie e, the haracteristic surface movement on this site. 5.2 Temporary Batter Slopes With the proposed development, limited room for the use of temporary batter slopes during construction as most of the building perimeter walls are very close to the boundaries. For the safe temporary batters are recommended as presented in Table 2, provided that the basement excavation is set back from the common site boundaries. Minor slumping and erosion can be controlled by covering the batter by geofabric. Table 2: Batter Slope Design Materials Exposed/Without support w Protected Silty and clayey soils (Residual Soil) 2.0:1.0 1.5:1.0 Weathered Sandstone bedrock 1.0:1.0 5.3 Retaining Structures The proposed basement footprint close to the site boundaries, the forming of basement will preferably need to adopt a construction methodology. In general, it is considered a contiguous pile wall system may be necessary to ensure that the excavation faces are protected at all times. Other methods such as a soldier pile, in wall with shotcrete infill panels can also be adopted or structural design block wall can also be adopted. These structures should be designed to withstand the applied lateral pressures of the subsurface soils layer, the existing surcharges in their zone of influence, and hydrostatic pressures if appropriate, using a triangular earth pressure distribution The pressure distribution on cantilever retaining structures may be assumed to be triangular and estimated as follows: ph = ɣkH + qk where specified: ph = Horizontal pressure (kN/m2)

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ɣ = Unit weight of soil (kN/m3) ka = Coefficient of earth pressure H = Retained height (m) q = Surcharge pressure on the high side of a retaining wall (kN/m2) Recommended parameters for the design of retaining structures are presented in the following Table 3. Table 3: Geotechnical Design Parameters Materials Unit Weight (kN/m3) Active Earth Pressure coefficient (Ka) At Rest Earth Pressure Coefficient (Ko) Effective Cohesion Friction Angle Residual Soil (Unit B & C) Table 1 19 0.35 0.5 10 28 Residual Soil Unit D(Table 1) 20 0.3 0.5 12 28 Sandstone V (Refusal material) 22 0.25 0.4 100 33 This is particularly the case for the retaining walls located immediately adjacent to the neighboring buildings. The retaining structures be anchored or strutted, the pressure distribution is assessed to be rectangular, with magnitude estimated as follows: ph = 0.65ɣkH It is also recommended any retaining structure should be checked for bearing capacity, overturning, and overall stability of the slope

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5.3 Wind Rating The maximum design gust wind speed for this site is 40 m/s based on wind speed calculations (Vh) for use in ultimate limit state design only calculated in accordance with the limitations as in AS4055. The Wind Rating for this site has been assessed as N2. Important notes relate to this site classification If a more detailed geotechnical investigation report is available for this site with regards to soil reactivity, Fusion Engineering Services should be provided this detailed investigation report. In addition, any details relate to this site history should be supplied to this office by the client. Upon reviewing these information Fusion Engineering Services may conduct a detailed geotechnical investigation as this report is not a detailed investigation report. This report was produced based on limited geotechnical investigation in line with the requirements of AS 2870-2011, CL2.2.2 (a). The above site classification is based on the soil investigation conducted on 18.11.2017, if the site conditions are changed from the original investigation date Fusion Engineering Services is not liable for any damages that may cause the client. 6. Foundation System and Allowable Bearing Pressures The following allowable bearing pressures can be adopted for the soils listed in the table below. These bearing pressures apply where typically the embedment is a minimum of 300mm into the specified material. Table2: Allowable Bearing Pressures Soil/ Rock Type Indicative Founding Depth (mm) BGL Minimum Allowable Bearing Capacity (kPa) very stiff Clay 800* 150 Highly weathered rock (Sandstone) Depth Varies 500 *Indicative founding depth is based on the drilled holes location. 7. Footing Design Based on the site classification an engineer designed foundation systems is required at this site. The foundation systems must be designed to cater for the potential movements associated with the drying effects of a tree or a group of trees. The designer may adopt the classification of the site soil Class M”.

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Deep footing systems such as bored piers, screw piles or trench blinding concrete may be considered. Found deep footings through any fill and into the undisturbed natural in-situ soil as described in in Table1. Where screw piles are considered, additional investigation may be required to establish in-ground corrosion parameters and likely pull-up depths. 8. Disposal of Excavated Materials All excavated materials, need to be dispose of offsite in accordance with the current Office of Environment and Heritage (OEH) regulations. It should be noted that under the Protection of the Environment Operation Act (2009). 9. Construction Techniques • Site should scrape a minimum 200mm to remove any organic materials and vegetation within the proposed building envelope. • Site should be track rolled after initial site scrape to unveil any soft spots, these soft areas to be removed and then properly compact with suitable fill material as described in AS2870-2011, cl 6.4.2 • Site drainage is very important in reactive sites, thereby we recommended that ground surface immediately next to the perimeter footings be graded away from the slab at a minimum of 1:20 grade for a minimum distance of 1.5m. • A second soil test should be conducted on this site if the site cut is more than 400mm clay soil and 800mm for sandy soil. • Any filling placed across the site for leveling benchmark prior to slab construction should fulfill the requirement AS 2870-2011. • As soon as the roof is constructed the roof drainage should be carried away from the slab to avoid water ponding around the slab perimeter. • 10. Report Limitation

• This report is not a detailed geotechnical investigation. It complies with the requirements of AS2870-2011 and is limited to the items required under Cl 2.2.2(a).

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• This report was compiled on basic geotechnical investigation only, if the subsurface soil conditions encountered during construction stage is different from what described on the soil report, please contact this office immediately. • This report does not assess the potential contamination, aggressive soil and Acid Sulphate soil. • Fusion Engineering Services endeavor to assess the pre site history with available sources. However, Fusion Engineering Services cannot be held responsibility for any financial loss in relation to the structure and future performances of the footing if the site history has not been supplied to this office in writing by the client. Please do not hesitate to contact this office, should there be any further queries. Regards

Arun Shrestha Civil/ Structural Engineer BE(Civil), MIEAust CPEng, NER, RPEQ, RBP C7- Accredited Certifier Membership No: 3079199 Phone: 0431607251 Email: arun@fusionengineering.com.au

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APPENDIX A Site Plan with Borehole Location

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APPENDIX B Borehole logs and DCP Test Result

Hole No: BH-01Date: 18/11/2017Logged: SGSurface RL:Test Method:Depth (m) SPT Graphic Log Unified Classification Description Moisture Condition Consistency/ Rel. Density Pocket Penetrometer1.0 Grey brown to red brown low to medium plasticity firm to stiff Silty Clay with traces of gravel 2.2 Grey to red brown stiff to hard medium plasticity silty Clay iron stone gravel

3.50 Grey, brown to grey white very stiff to hard medium plasticity silty Clay iron stone gravelBH treminated on class V sandstone Rock at 3.5mConsistency Density MoistureSoft s Very Loose VL D DryFirm f Loose L SM Slightly MoistStiff st Medium Dense MD M MoistVery Stiff vst Dense D VM Very MoistHard h Very Dense VD W Wetvery hard vh

Hole terminated upon the refusal of class V sandstone rock at 3.5mvst-hDJob No: 2017-2384GQClient:MOUNT COLAH DEVELOPMENT PTY LTD -Location: 510-516 Pacific Hwy, Mt Colah Auger/DCP Additional Comments

st-hf-st0.3 CL Grey, silty Clay with some Gravel -

Hole No: BH-02Date: 18/11/2017Logged: SGSurface RL:Test Method:Depth (m) SPT Graphic Log Unified Classification Description Moisture Condition Consistency/ Rel. Density Pocket Penetrometer1.0 Grey brown to red brown low to medium plasticity firm to stiff Silty Clay with traces of gravel 2.8 Grey to red brown stiff to hard medium plasticity silty Clay iron stone gravel

4.50 Grey, brown to grey whred brown te very stiff to very hard medium plasticity silty Clay iron stone gravelBH treminated on very hard clay at 4.5mConsistency Density MoistureSoft s Very Loose VL D DryFirm f Loose L SM Slightly MoistStiff st Medium Dense MD M MoistVery Stiff vst Dense D VM Very MoistHard h Very Dense VD W Wetvery hard vh

DJob No: 2017-2384GQClient:MOUNT COLAH DEVELOPMENT PTY LTD -Location: 510-516 Pacific Hwy, Mt Colah Auger/DCPAdditional Comments0.3

CL Grey, silty Clay with some Gravel

- Hole terminated upon the limitation of scope at 4.5mf-stst-hvst-vh

Hole No: BH-03Date: 18/11/2017Logged: SGSurface RL:Test Method:Depth (m) SPT Graphic Log Unified Classification Description Moisture Condition Consistency/ Rel. Density Pocket Penetrometer0.6 Grey brown Sandy gravelly Clay(Fill)1.6 Yellow to red brown stiff to hard medium plasticity silty Clay iron stone gravel BH treminated on class V sandstone Rock at 1.6m

Consistency Density MoistureSoft s Very Loose VL D DryFirm f Loose L SM Slightly MoistStiff st Medium Dense MD M MoistVery Stiff vst Dense D VM Very MoistHard h Very Dense VD W Wetvery hard vh

DJob No: 2017-2384GQClient:MOUNT COLAH DEVELOPMENT PTY LTD -Location: 510-516 Pacific Hwy, Mt Colah Auger/DCP Additional Comments0.3 CL Grey, silty Clay with some Gravel(Top Soil) - Hole terminated upon the refusal of class V sandstone rock at 1.6mst-h

Hole No: BH-04Date: 18/11/2017Logged: SGSurface RL:Test Method:Depth (m) SPT Graphic Log Unified Classification Description Moisture Condition Consistency/ Rel. Density Pocket Penetrometer0.7 Grey brown Sandy gravelly Clay(Fill)1.6 Yellow to red brown stiff to hard medium plasticity silty Clay iron stone gravel BH treminated on class V sandstone Rock at 1.6m

Consistency Density MoistureSoft s Very Loose VL D DryFirm f Loose L SM Slightly MoistStiff st Medium Dense MD M MoistVery Stiff vst Dense D VM Very MoistHard h Very Dense VD W Wetvery hard vh

st-hDJob No: 2017-2384GQClient:MOUNT COLAH DEVELOPMENT PTY LTD -Location: 510-516 Pacific Hwy, Mt Colah Auger/DCPAdditional Comments0.3 CL Grey, silty Clay with some Gravel(Top Soil) - Hole terminated upon the refusal of class V sandstone rock at 1.6m

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APPENDIX C Photograph

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