GEOTECHNICAL INVESTIGATION PROPOSED FOOTBRIDGE OVER EXISTING TRACK Motoring South West Distribution Record: Revision Reviewed By Date Issued Purpose of Issue Issued To A SM 10/01/2019 Draft for comments Steve Brake Prepared by: Greg Tomasini Signed: Date: 10 January 2019 WML Name: Collie Motorplex Footbridge Additional GI WML Project No: 8318 Date: 10 January 2019 Page i Report Name: 8318-G-R-001.docx About your geotechnical investigation and report…………. A geotechnical investigation is planned and conducted solely for the intended recipient of the report and for the purposes stated in the report. The report should not be reproduced in whole or part without agreement of WML Consultants. A geotechnical investigation is planned and conducted based upon the information about the site and proposed works that is made available to WML Consultants, as stated in the report. A geotechnical investigation typically includes investigation and testing at a few isolated locations. The choice of the locations is usually made by the author having consideration for the nature of the site and proposed works. Conditions for the remainder of the site are necessarily extrapolated from the conditions observed at the locations investigated. Thus the report will contain a mixture of facts, interpretation and professional judgement. Facts will usually be confined to a description of the fieldwork carried out, the observations made and any results of laboratory testing. However, field notes and logs contain estimates of conditions observed at the time, and may differ from the results obtained from subsequent laboratory testing of samples. Other comments and conclusions should be considered as interpretation and professional judgement, unless specifically stated otherwise. As the nature of geotechnical conditions is so variable WML Consultants accepts no liability or responsibility for the conditions encountered beyond the limits of our investigation. Such conditions may exist between test locations or in deeper strata than observed than can reasonably be interpreted from the limited extent of this investigation. For various reasons (e.g. seasonal effects), the site conditions encountered during construction may differ from those observed or extrapolated from the initial investigation. In this instance the recommendations in the geotechnical report may not be appropriate and it is strongly recommended WML Consultants be requested to inspect the different conditions, review the initial report and provide follow-up advice. Unless specifically allowed for in the brief, the follow-up review will attract an additional fee. Date: 10 January 2019 Report Name: 8318-G-R-001.docx CONTENTS 1 INTRODUCTION ........................................................................................................................................................... 3 2 SITE SETTING ................................................................................................................................................................ 3 2.1 SITE LOCATION AND DESCRIPTION ................................................................................................................... 3 2.2 GEOLOGY .......................................................................................................................................................... 4 3 GROUND INVESTIGATION ...................................................................................................................................... 4 3.1 SERVICE LOCATION ........................................................................................................................................... 4 3.2 FIELDWORK ....................................................................................................................................................... 4 4 CPT ANALYSIS .............................................................................................................................................................. 4 5 FINDINGS AND RECOMMENDATIONS............................................................................................................... 5 5.1 SUB-SURFACE PROFILE ..................................................................................................................................... 5 5.2 DESIGN PARAMETERS ....................................................................................................................................... 6 5.3 SITE PREPARATION ........................................................................................................................................... 6 5.4 SAFETY IN DESIGN ............................................................................................................................................. 7 6 REFERENCES ................................................................................................................................................................. 7 APPENDIX A SITE INVESTIGATION MAP APPENDIX B SOIL LOGS APPENDIX C PREVIOUS REPORT Date: 10 January 2019 Report Name: 8318-G-R-001.docx 1 INTRODUCTION Previously Calibre Consulting on behalf of their client, Motoring Southwest, requested a geotechnical investigation for a proposed footbridge over the existing track. The purpose of the investigation was to ascertain the subsurface profile, soil strength, bearing capacity and possible settlement at the site. WML undertook the following scope of work as part of that appointment: • 4 machine excavated test pits to approximately 2m depth • 4 CPTs to 6m or refusal • Logging of boreholes and collecting of samples • Sampling of representative subgrade materials for laboratory testing. • Taking notes and photographs of the site. A report (7524-G-R-001) presenting the findings of the previous investigation is attached. Since the previous report was issued the footbridge has been moved approximately 25 meters from the original position and as such WML was appointed to undertake a follow-up geotechnical investigation with the same purpose at the new location. The scope of works for the new locations included the following: • 2 machine excavated test pits to approximately 2m depth • 2 CPTs to 6m or refusal • Logging of boreholes • Taking notes and photographs of the site This report presents the findings of the investigation. 2 SITE SETTING 2.1 Site Location and Description The Motorplex is located approximately 15 km southeast of Collie. The Motorplex will undergo development including the construction of a pedestrian footbridge over the race track, located near to the existing control tower. Investigation is required at the two foundation locations. It is assumed the bridge will be founded on spread footings. An image of the proposed bridge is shown below: Date: 10 January 2019 Report Name: 8318-G-R-001.docx 2.2 Geology The near surface ground conditions are relevant to the bridge foundations and an appropriate investigation technique (discussed further in Section 3). The general sub-surface geology at the site consists of: • 0-3m depth: superficial sand, gravel and cap rock. • 3-30m depth: Nakina Formation (weakly cemented sandstone and claystone with a laterite hard cap). The 1:50,000 scale geological map places the site upon ‘Sand’ and states that the area has been affected by mining activities. 3 GROUND INVESTIGATION 3.1 Service Location A “Dial before You Dig” search for services was carried out before any excavation occurred. Power and telecommunications services were found to be servicing the Motorplex however they were not located in the vicinity of the work area. Electrical services were present for the start line timing equipment however these were also not in the immediate work area. 3.2 Fieldwork The fieldwork was carried out on 7th January 2019 by an engineer from WML. The fieldwork consisted of the following works. • 2 machine excavated test pits to approximately 2m depth. • 2 CPTs GPS location and photographs were also taken of the site. The locations of the test pits are shown on Drawing 8318-G-001 with the test pit logs presented in the Appendices. 4 CPT ANALYSIS CPT analysis was undertaken at 2 locations on site. CPT 1 and 2 were progressed to the target depth of 6m. The analysis of CPT1 and CPT 2 are shown below. Date: 10 January 2019 Report Name: 8318-G-R-001.docx Figure 1: CPT 1 Figure 2: CPT 2 5 FINDINGS AND RECOMMENDATIONS 5.1 Sub-Surface Profile TP1 located at Abutment 1: • GRAVELLY, SILTY SAND 0 - 0.65m – Some cementation was present in the material. • ASPHALT SEAL - 0.65 – 0.7m – Old haul road seal • SANDY GRAVEL – 0.7 - 1.25m – Haul road basecourse material • SILTY SAND – 1.25 – 1.9m – Very dense material Date: 10 January 2019 Report Name: 8318-G-R-001.docx TP2 located at Abutment 2: • SILTY SAND TOPSOIL - 0 - 0.15m – Grass and roots present. • SANDY GRAVEL – 0.15 - 0.35m – Old gravel basecourse material • SILTY SAND – 0.35 – 0.45m • GRAVELLY SAND – 0.45 – 0.9m • SILTY SAND – 0.9+m – Very dense material 5.2 Design Parameters Abutment 1: 0 to1.3m Abutment 2: 0 to 2.0m Medium Dense Clayey / Silty Sand and Sandy Silt Fill Parameter Design Value E (Young’s modulus) 25 MPa Φ (angle of internal friction) 32° Cu (cohesion) 0 kPa g (unit weight) 18 kN/m3 Abutment 1: 1.3 to 6.0m Abutment 2: 2.0 to 6.0m Very Stiff/Dense Soils Parameter Design Value E (Young’s modulus) 50 MPa Φ (angle of internal friction) 36° Cu (cohesion) 0 kPa g (unit weight) 18 kN/m3 5.3 Site Preparation The existing in-situ material is well compacted. If existing material is over excavated