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Preliminary Site Investigation Part 2 M Eco Logical Australia METRONET Morley-Ellenbrook Line Preliminary Site Investigation Part 2: Malaga to Ellenbrook Section MEL-MNO-COFF-EN-RPT-0011 04 May 2020 This page has been left intentionally blank METRONET Morley-Ellenbrook Line Preliminary Site Investigation Part 2: Malaga to Ellenbrook Section Prepared for Eco Logical Australia Prepared by Coffey Services Australia Pty Ltd Level 1, Bishops See, 235 St Georges Terrace Perth WA 6000 Australia t: +61 8 6218 2100 f: +61 8 6218 2222 ABN 55 139 460 521 04 May 2020 MEL-MNO-COFF-EN-RPT-0011 754-PEREN233882 Quality information Revision history Revision Description Date Originator Reviewer Approver Draft A Draft 07/02/2020 Geri Matthew Pethebridge/Nick Chenery Taylor Draft B Draft for client review 13/02/2020 Nick Taylor Matthew Matthew Chenery Chenery Draft C Draft for client review 17/02/2020 Nick Taylor Cameron Cameron Baldock Baldock Rev0 Issued for Use 20/04/2020 Nick Taylor Cameron Cameron Baldock Baldock Rev1 Issued for Use 04/05/2020 Nick Taylor Cameron Cameron Baldock Baldock Distribution Report Status No. of copies Format Distributed to Date Rev0 1 PDF METRONET and ELA 20/04/2020 Rev1 1 PDF METRONET and ELA 04/05/2020 Coffey Services Australia Pty Ltd i ABN 55 139 460 521 Executive Summary Coffey Services Pty Ltd (Coffey) were engaged by EcoLogical Australia (ELA) to undertake a Preliminary Site Investigation (PSI) for contamination along the alignment Development Envelope (DE) of the Morley-Ellenbrook Line (MEL). The development of the MEL project is being led by the METRONET office, while the Public Transport Authority (PTA) of Western Australia is the projects formal proponent. For the purpose of this study, and at the request of the PTA, the PSI has been completed in two sections, known as Part 1 and Part 2. This report covers the Part 2 area referred to as the Malaga to Ellenbrook Rail Works. The main objective was to undertake a PSI to identify the presence of possible contaminating activities, as a result of both historical or current land use, that may have implications on the construction of the MEL project. The Scope of Works (SoW) consisted of three main elements: A broad desktop assessment of the study area; A targeted desktop assessment for selected areas within the study area; and Targeted site inspections within selected areas of the study area. A review of available information led to the creation of a Conceptual Site Model (CSM) for the study area, which found that the main land uses associated with the majority of known and potential sources of contamination across the study area were past water treatment and disposal (landfill) facilities, agriculture and road infrastructure. Another major risk identified was the potential for Acid Sulfate Soil (ASS) generation particularly considering the number of wetland areas throughout the study area. Secondary risks were associated with uncontrolled fill and fly tipping activities. The main exposure risks were identified as dermal contact, ingestion and vapour inhalation by current and future site users and workers and vertical and lateral flow of contaminated groundwater to groundwater users and surface water features such as wetlands. A number of management plans will be required to manage the identified risks during construction and a review of the results of upcoming site investigations at the former Gnangara Waste Facility should be undertaken when considering the appropriate management measures for groundwater during excavation and dewatering works associated with the construction of the new road bridge at the Gnangara Road and Drumpellier Drive intersection. A summary of the data gaps identified and the recommended actions to address them are presented in Table E-1 below. Table E-1: Identified data gaps and recommendations Site Data Gap Identified Recommendations Lexia Liquid Waste Disposal Site The full extent of waste material It is understood that further works (Landfill) Gnangara, located within has not been delineated and the are to be undertaken by GHD on reserve State Forest 65, Lexia WA soil contamination has not been behalf of DPLH. These should 6065 and Lot 811 on deposited clearly defined. Groundwater further assess the presence of plan 405371 (233 Drumpellier contamination has not been waste materials and the extent of Drive) laterally and vertically delineated in soil contamination and improve the any direction. definition and delineation of the groundwater plume. The requirements for further works to assess risk to the MEL project should be determined based on the outcomes of the GHD investigations. Coffey Services Australia Pty Ltd ii ABN 55 139 460 521 Site Data Gap Identified Recommendations A Groundwater Management Plan (GMP) should be compiled to manage the risks associated with groundwater abstraction in this area. Intensive agriculture including There are no classified sites within If excavation works take place in feedlots and saleyards, (i.e. Swan the Development Envelope and no the vicinity or down hydraulic Valley Egg Farm) known contamination. However, gradient of any identified intensive there is potential for contamination agricultural source then it is to be encountered in soil and recommended that soil and groundwater if excavation works groundwater testing should be take place in areas of intensive undertaken for Potential agricultural use, (i.e. Swan Valley Contaminants of Concern, (PCoCs) Egg Farm is within the associated with this land use to Development Envelope). assess risks to the project. Entire study area More targeted investigations may Target investigations have be required based on results of occurred across the alignment (Acid Sulfate Soils – ASS) recent ASS investigations, which however, an ASS Management can then be used to fully assess Plan should be developed together the risk posed by ASS to help with further targeted investigations inform an adequate ASS in areas of high risk, if required. Management Plan. Engineering consideration should also be given to the risk to built structures, i.e. potential deterioration of pilings and foundations. Entire study area Assessment of areas of potential Formulation of a Construction fly-tipping required. Environmental Management Plan, (Fly Tipping) (CEMP) or similar with management measures for dealing with fly tipping when this occurs. Entire study area Both the extent and likelihood of Compilation of CEMP, or similar to encountering uncontrolled fill deal with unidentified contaminated (Uncontrolled fill) material is currently unknown. soils where these are encountered. Entire study area Extent and likelihood of Compilation of CEMP for uncontrolled fill and fly tipping management of risks associated (Road Infrastructure) associated with road infrastructure with site run-off, unidentified is currently unknown. Control contaminated soils and fly tipping measures for dealing with surface and compilation of a Groundwater run-off also required. Management Plan (GMP) for areas affected by groundwater contamination and where deep excavation and dewatering works are required. Coffey Services Australia Pty Ltd iii ABN 55 139 460 521 Table of contents Executive Summary ............................................................................................................................ ii Table of contents ................................................................................................................................ iv 1. Introduction .................................................................................................................................. 1 1.1. Project Understanding ....................................................................................................... 1 1.2. Objectives .......................................................................................................................... 1 1.3. Scope of Work ................................................................................................................... 2 1.3.1. Assessment 1: Broad desktop assessment within the study area ....................... 2 1.3.2. Assessment 2: Targeted desktop assessment of selected areas within the study area 3 1.3.3. Assessment 3: Targeted site inspection – selected areas within the study area. 3 1.3.4. Report Structure ................................................................................................... 3 2. Methodology ................................................................................................................................ 5 2.1. Data Review ...................................................................................................................... 5 2.2. Site Inspections ................................................................................................................. 6 3. Site Information ........................................................................................................................... 7 3.1. Site Identification ............................................................................................................... 7 3.2. Surrounding Land Uses .................................................................................................... 7 3.3. Environmental Setting ....................................................................................................... 8 3.3.1. Topography .......................................................................................................... 8 3.3.2. Regional