Contaminated Sites

Investigation, assessment, remediation and validation – delivered to regulatory standard.

Contaminated sites represent some of the most technically complex and commercially significant environmental liabilities facing landowners, developers and industrial operators in Australia.

Whether contamination is the legacy of past industrial activity, the result of a recent spill or release, or an uncertain risk identified during due diligence for an acquisition or divestment, it demands careful, systematic investigation by qualified practitioners working within a clearly defined regulatory framework.

In Western Australia, the assessment and management of contaminated sites is governed by the Contaminated Sites Act 2003 and its associated regulations, administered by the Department of Water and Environmental Regulation (the regulator). The national technical framework is provided by the National Environmental Protection (Assessment of Site Contamination) Measure 1999 (ASC NEPM), as amended in 2013. Together, these instruments establish the processes for site classification, investigation, remediation, validation and ongoing management that RED OHMS Group follows in delivering contaminated sites services.

RED OHMS Group’s contaminated sites team works with mining and resources companies, property developers, government agencies and private landowners to investigate and manage contaminated sites across Western Australia. Our environmental scientists bring experience with a wide range of contaminant types – petroleum hydrocarbons, chlorinated solvents, heavy metals, asbestos-in-soil, acid mine drainage and process chemicals – and across a variety of land use settings from urban industrial sites to remote pastoral and mining leases.

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Capabilities

PSIs consolidate historical land use information, aerial photograph review, the regulator contaminated sites register searches and site inspection observations to develop a preliminary Conceptual Site Model (CSM) and identify areas of potential concern. DSIs involve intrusive investigation – soil sampling, groundwater monitoring well installation and sampling, vapour assessment – to characterise the nature and extent of contamination and develop a refined CSM.

Development of site-specific RAPs that define remediation objectives, select and justify appropriate remediation technologies and specify implementation and monitoring requirements. Project management of remediation works including contractor procurement, supervision, quality assurance and progress reporting.

Where contamination cannot be fully remediated to background levels, an SMP documents the ongoing management controls (land use restrictions, monitoring, maintenance) required to manage residual risk. SVRs document the outcomes of completed remediation works and provide the evidence required for the regulator to reclassify the site as remediated for restricted use or remediated for unrestricted use.

Assessment of potential asbestos-contaminated soils in accordance with the regulator guidance and the National Environment Protection (Assessment of Site Contamination) Measure 2013 (Asbestos Amendment). Includes site history review, asbestos identification sampling, risk characterisation and remediation planning where required.

Phase 1 and Phase 2 environmental due diligence assessments for property transactions, asset acquisitions and project financing. Provides prospective buyers, sellers and financiers with a documented assessment of environmental liability and risk associated with the land or asset.

Assessment of ground conditions relevant to contaminated sites investigations, including soil characterisation, permeability testing and geological logging to support CSM development and remediation design.

The Contaminated Sites Classification System in WA

Under the Contaminated Sites Act 2003, the regulator classifies sites on a public register according to their contamination status.

Classification carries significant practical and commercial implications – a site classified as ‘contaminated – remediation required’ must be remediated or managed to the regulator’s satisfaction before the classification will change and the classification is publicly available and will be disclosed in property searches. Landowners and operators have reporting obligations when they know or suspect contamination exists.

For organisations with multiple sites or complex asset portfolios, maintaining awareness of contamination classification status and managing the regulatory obligations associated with classified sites is an ongoing challenge. RED OHMS Group can assist with contamination status reviews across portfolios, prioritisation of investigation and remediation activity and the regulator engagement to progress site reclassification.

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FAQs

A Conceptual Site Model (CSM) is a structured representation of the potential contamination sources at a site, the pathways by which contaminants may migrate through the environment and the receptors (people, ecological systems, groundwater, surface water) that may be exposed. The CSM is the intellectual foundation of a contaminated sites investigation – it drives decisions about where to sample, what to analyse for and how to interpret results. A poorly developed CSM leads to investigations that miss key contamination pathways and reports that do not satisfy regulators. RED OHMS invests significant effort in developing robust, evidence-based CSMs at the outset of every investigation.

Under section 11 of the Contaminated Sites Act 2003, any person who knows or suspects that a site is contaminated is obliged to report it to the regulator. This obligation extends to landowners, occupiers and those responsible for activities that may have caused the contamination. The obligation is triggered by knowledge or reasonable suspicion – it is not limited to confirmed contamination. RED OHMS can advise on your reporting obligations and assist in making the required notification to the regulator.

Timeframes vary enormously depending on the nature and extent of contamination, the remediation technology selected and the regulatory process. A straightforward PSI and DSI for a small industrial site might be completed in three to six months. Remediation of a complex groundwater contamination plume – particularly where natural attenuation is the selected approach – may require years of monitoring and progressive reporting. RED OHMS provides realistic programme schedules based on site-specific conditions and the regulator engagement, not optimistic assumptions.