Remediation of Coatings Manufacturer Site, Western Sydney

Project summary

iEnvi developed and implemented a statutory-compliant, commercially oriented remediation solution for a coatings manufacturer site in Western Sydney. Work delivered by iEnvi included groundwater and plume delineation, removal and validation of underground storage tanks (USTs), source-zone treatment, soil remediation with beneficial reuse where appropriate, a human health and environmental risk assessment (HHERA), and an intensive four-month Multiphase Vapour Extraction (MPE) programme. The program was due for completion in June 2018 and was endorsed by a NSW EPA Accredited Contaminated Sites Auditor.

Site context and key issues

• The site previously stored solvents in underground storage tanks. Historical leaks released solvents, including methyl ethyl ketone (MEK), to the subsurface.
• A downgradient concrete-lined stormwater canal was identified as a potential environmental receptor requiring compliance with NSW EPA policy.
• Prior remediation activity over a prolonged period had not fully delineated impacts or removed the principal source, resulting in on-going dissolved-phase contamination and regulatory uncertainty.

Remediation strategy (commercial and regulatory drivers)

The remediation strategy was designed to meet three commercial objectives: reduce regulatory uncertainty, enable continued industrial use, and materially improve the site’s commercial value. The approach, endorsed by the appointed Auditor and presented to the client’s board, included the following components:

• Source removal and validation: removal of USTs and associated infrastructure with site validation to eliminate continuing releases.
• Source-zone treatment: in-place treatment using chemical oxidation and targeted soil remediation to reduce mass remaining in the source area.
• Soil remediation and beneficial reuse: excavation and treatment where required, with reclassification and beneficial reuse options to reduce waste disposal costs.
• Aquifer and plume delineation: detailed groundwater monitoring and sampling to define offsite impacts and the vertical and lateral extent of dissolved-phase contamination.
• Further assessment: targeted additional testing (soil, soil vapour, groundwater) to inform the remedial design.

Primary remediation technology — Multiphase Vapour Extraction (MPE)

Based on pilot trials and operational constraints, a four-month intensive MPE programme was selected as the primary method for combined soil vapour and dissolved-phase remediation. Plain-English definition: Multiphase Vapour Extraction (MPE) is a remediation technique that simultaneously extracts vapour, free-product (if present) and groundwater to remove volatile and semi-volatile contaminants from the subsurface.

Outcomes from the pilot and initial programme indicated the MPE system would remove a significant proportion of residual dissolved hydrocarbon mass. The estimate presented at the time was approximately 40% of the total estimated residual dissolved hydrocarbon mass in the aquifer, based on the pilot trial results.

Risk assessment and compliance

An HHERA concluded that the site presented an acceptable human health risk for its ongoing industrial use provided specific controls were implemented. These controls were documented within an Environmental Management Plan (EMP) and focused on managing exposure risks during subsurface excavation and routine site works.

The program design and the Auditor endorsement provided NSW EPA with confidence that an effective, proactive management strategy was in place, reducing uncertainty in future regulatory approvals for the selected scope of works.

Remediation outcomes and commercial benefits

• Removal of the source (USTs) eliminated an ongoing release pathway, a precondition for meaningful long-term groundwater improvement.
• Pilot-validated MPE achieved rapid mass removal consistent with commercial timeframes and minimized disruption to ongoing operations compared with longer-duration in-situ approaches.
• Targeted soil remediation and beneficial reuse reduced waste volumes and disposal cost, improving project economics.
• The combined approach reduced regulatory uncertainty, creating a clear basis for board-level decisions and materially improving the site’s marketability and value.

Practical takeaways for buyers, owners and developers

• Prioritise source removal (USTs, infrastructure) before long-term plume interventions — ongoing sources frustrate remediation and increase costs.
• Use short, pilot-tested intensive interventions (like MPE) where rapid mass reduction is commercially important and site operations must continue.
• Integrate HHERA findings into an EMP to support safe excavation and redevelopment while retaining regulatory confidence.
• Consider beneficial reuse of remediated soils to reduce disposal costs and improve project economics, but only where regulatory and technical criteria are satisfied.
• Engage an Accredited Auditor and the regulator early to align remediation scope to approval expectations and reduce transaction risk.

Contact iEnvi

For pragmatic remediation design and approvals support that balances compliance, risk and commercial outcomes, contact iEnvi on 13000 43684 or visit /contact/.