Remediation of former gas works

CGL was commissioned to review the results of a previous ground investigation and conduct further explorations at this former gas works, prior to the site being redeveloped into residential properties. We confirmed evidence of shallow groundwater and soil contamination due primarily to elevated concentrations of hydrocarbons (TPH and PAH), ammonia and cyanide. Subsequently, a DQRA was undertaken following the Environment Agency’s remedial targets methodology to determine these remedial targets.

On the basis of these results, CGL produced a Remediation Implementation Plan (RIP) which was then agreed with the Environmental Health Officer and Environment Agency. This demonstrated that the groundwater beneath the site was unlikely to adversely impact the River Tutt via the aquifer, but that soil remediation was necessary to mitigate the risk of potential future damage.

CGL assisted in the tender process and appointment of the remediation contractor.

These works included hot spot excavations and on-site bio remediation of impacted soil, with selected off-site disposal. CGL supervised the soil removal, verifying the remediation efforts and ensuring protection of surface water. CGL assessed the performance of the bio remediation on a risk basis related to the final land use and redevelopment.

CGL also acted as the spokesperson, liaising with concerned residents whilst the site was undergoing these remediation works.

Finally, CGL produced a verification report for issue to the regulators in compliance with the planning conditions for the development. Additional remediation works verified by CGL included gas protection measures and capping layers in landscaping areas.