Environmental Site Assessment

Contaminated Land Management

Environmental site assessments (ESAs) are undertaken to investigate contamination of soil, surface water, groundwater or soil vapour at a facility or property, arising from past or current activities at the facility or in the surrounding area. ESAs may be conducted for a variety of reasons including site owner/occupier due diligence, Council planning approvals, purchaser/vendor/merger due diligence or as part of a requirement of 53X and 53V Environmental Audits.

Types of Environmental Audits

Preliminary site investigations (PSI or Phase I) generally involves a desktop investigation, including review of site history and EPA registers to assess the requirement for further intrusive investigations. A detailed site investigation (DSI or Phase II) involves intrusive works to investigate the presence or absence of soil, surface water, asbestos, groundwater and/or soil vapour contamination. A DSI/Phase II will typically assess the potential risks to human health and/or the environment at the site (and neighbouring sites) posed by potential:

      • Soil contamination
        Soil contamination can arise when:
          • It has been mixed with waste material
          • It has been mixed with soil from an unknown origin (i.e. imported fill material)
          • Impacted from activities where former uses including industrial, commercial, mining or agricultural activities have occurred on-site
          • Manufactured chemical has been applied to the material
          Specific soil sampling activities undertaken and managed by Edge include:
          • Underground service location referencing Dial Before You Dig (DBYD) and using underground service detection methods
          • Non-destructive digging
          • Soil boring using manual and mechanical drill rig
          • Test pitting
          • Trenching
          • Stockpile management
          • Reinstatement of opened ground
          • Soil disposal
          • Soil remediation
          • Sourcing and clearance for “clean fill” introduced to site

        • Surface water contamination
          Surface water contamination can occur through surface runoff, discharge directly into a water way or from an up-gradient source of contamination. Surface water monitoring is useful to:
          • Assess land use impact
          • Assess source point impact
          • Assess surface water quality
          • Identify the presence of algae blooms
          • Monitor contamination across a catchment area
          • Assess concentration changes over time and identify trends
          • Assess the effectiveness of rehabilitation or remediation

        • Groundwater contamination
          Groundwater quality assessments are necessary to determine the extent of contamination and the risk to the environmental and human health. Edge can manage groundwater assessments from the planning to implementation and review phase including:
          • Determining targeted locations for well installations
          • Determine appropriate drilling method for well installation considering the site geology, the contaminants of concern, quality of core, volume of waste
          • Underground service clearance prior to well installation
          • Supervision of drilling and well installation
          • Determine the appropriate depth of drilling to target the water table
          • Develop the wells to remove all fines and encourage water flow
          • Conduct groundwater monitoring events (GME) using a variety of techniques
          • Review field quality data and chemical analysis
          • Develop trend data and contour plots
          • Groundwater fate and transport modelling
          Edge has provided the EPA and EPA Environmental Auditors sufficient information to achieve Clean Up To the Extent Practicable (CUTEP) determination for several sites in Victoria and interstate. Edge personnel have extensive experience managing national and long term GME programs for large oil and gas companies.

    • Soil vapour contamination
      Where soil and/or groundwater has been noted to contain volatile contaminants (e.g. fuels, solvents, etc.) soil vapour may be present and a potential risk may exist to site users or visitors. Depending on the type of contaminant, soil vapours can cause serious acute and chronic health effects if not appropriately managed.
      Edge provides the following specialist soil vapour assessment capabilities:
      • Installation of soil vapour bores – both permanent and temporary
      • Installation of VaporPin™ sub-slab sampling devices
      • Installation of monitoring wells for landfill gas migration monitoring
      • Purging and leak testing of soil vapour sampling points and sample trains using helium and/or isopropyl alcohol
      • Active soil vapour sampling using vacuum canisters (‘Summa’ or ‘Silonite’ type)
      • Active soil vapour sampling using sorbent tubes, thermal desorption tubes, etc.
      • Passive soil vapour sampling (various methods including Waterloo Membrane Sampler™, Radiello®, SKC, etc.)
      All of these media can be audited for contaminant type, depth and extent, through the collection and analysis of samples, where required. Requirements for additional works including environmental management, mitigation and/or remediation “clean up” is required at the site.
      Edge manages all aspects of the project including development of plans and specifications according to the results of the Phase I and II assessments, obtaining bids from qualified contractors should intrusive work be required and liaising with regulatory authorities.

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