Reference Document - OPW25 0085 (AS Published)

Contents
1.    Introduction ............................................................................................................................................................ 1
2.    Proposed Development ....................................................................................................................................... 1
3.    Aims & Method of investigation .......................................................................................................................3
      3.1 Fieldwork ...................................................................................................................................................................... 3
      3.2 Laboratory Testing ................................................................................................................................................... 3
4.    Results of Investigation ...................................................................................................................................... 4
      4.1 Site Description ......................................................................................................................................................... 4
      4.2 Topography................................................................................................................................................................. 7
      4.3 Surface Drainage ....................................................................................................................................................... 7
      4.4 Vegetation ................................................................................................................................................................... 8
      4.5 Buildings and Other Structures ........................................................................................................................... 8
      4.6 Geology ........................................................................................................................................................................ 8
      4.7 Subsurface Conditions ............................................................................................................................................ 9
      4.8 Groundwater............................................................................................................................................................. 10
      4.9 Geotechnical Laboratory Test Results ............................................................................................................. 11
5.    Slope Stability Assessment ............................................................................................................................... 12
      5.1 Existing Conditions................................................................................................................................................. 12
      5.2 Slope Stability Assessment.................................................................................................................................. 13
           5.2.1     Qualitative Assessment ....................................................................................................................... 13
           5.2.2     Numerical Modelling ........................................................................................................................... 14
6.    Geotechnical Recommendations ..................................................................................................................... 16
      6.1 Site Layout and Geotechnical Constraints..................................................................................................... 16
      6.2 Earthworks ................................................................................................................................................................. 16
           6.2.1   Site Preparation and Trafficability................................................................................................... 16
           6.2.2   Excavations .............................................................................................................................................. 17
           6.2.3   Batter Slopes ........................................................................................................................................... 18
           6.2.4   Filling ......................................................................................................................................................... 18
      6.3 Building Foundations ............................................................................................................................................ 19
           6.3.1   Site Classification .................................................................................................................................. 19
           6.3.2   Footing Design....................................................................................................................................... 19
      6.4 Retaining Structures .............................................................................................................................................. 20
      6.5 Drainage ..................................................................................................................................................................... 21
      6.6 Pavement Design Parameters ............................................................................................................................ 22
      6.7 Geotechnical Certification of Operational Works ....................................................................................... 22
7.    Wastewater Treatment and Disposal ............................................................................................................ 23
      7.1 Wastewater Flow Design Allowance ................................................................................................................ 23
      7.2 Terrain-Soil Assessment ....................................................................................................................................... 23
      7.3 Recommendations ................................................................................................................................................. 24
           7.3.1   System Type ............................................................................................................................................ 24
           7.3.2   System Positioning ............................................................................................................................... 24
           7.3.3   System Construction ............................................................................................................................ 26


Geo-Environmental Investigation for Proposed Subdivision
7 February 2025 | 24386-001-Rev0                                                                                                                                                        iv