EHS Support delivered a comprehensive assessment, remediation and rehabilitation program for a 200 ML pilot pond following the identification of potential historical seepage and associated environmental risks. The project involved full lifecycle environmental management, from preliminary hydrogeological assessment and detailed site investigation through to remediation, validation and regulatory closure.
Preliminary Assessment
EHS Support undertook an initial hydrogeological and geochemical review to assess whether groundwater conditions were consistent with historical seepage from the pond. The review considered historical monitoring data, salinity and ion ratio trends, hydrostratigraphy, and groundwater flow characteristics.
The assessment indicated that groundwater conditions were not consistent with infiltration of pond water and were more likely explained by natural variability and broader catchment hydrogeology. These findings were subsequently confirmed through detailed field investigations.
Detailed Hydrogeological and Contamination Assessment
EHS Support designed and implemented a comprehensive site investigation program that included:
- groundwater monitoring and sampling to assess water quality trends and identify any localised influence from the pond;
- soil investigations within and surrounding the pond footprint to define the nature and extent of potential impacts;
- characterisation of background soil conditions to establish assessment benchmarks;
- development of an updated conceptual site model integrating geological, hydrogeological and geochemical data; and
- assessment of pond water, soil and groundwater chemistry to evaluate potential seepage pathways and distinguish pond-related influences from natural background conditions.
The investigation confirmed that impacts were limited to shallow, localised surficial soils within the former pond footprint, with no evidence of impacts to groundwater beyond the immediate pond area.
Remediation and Rehabilitation
Based on the investigation findings, EHS Support developed and implemented a targeted remediation and rehabilitation program that included:
- excavation and management of impacted shallow soils within the pond footprint;
- regrading and stabilisation of the landform to restore drainage and minimise erosion risk;
- soil amelioration and reinstatement to support long-term land stability and compatibility with surrounding land use; and
- validation sampling and inspections to confirm remediation objectives had been achieved and residual risks appropriately managed.
Regulatory Support and Project Outcomes
EHS Support provided specialist technical support throughout engagement with the regulator, including presentation of the investigation methodology, conceptual site model, assessment findings and remediation outcomes. The team also addressed technical queries relating to salinity, groundwater behaviour and remediation effectiveness.
Clear communication of the technical findings, combined with a robust evidence base, supported timely regulatory acceptance of the works. The project was successfully closed with no requirement for further investigation or remediation.