Decades of heavy industrial activity on the former Anglesey Aluminium site had left a legacy of significant contamination, with diesel leaks from underground tanks, oil spills from industrial compressors and fire damage incidents leading to transformer oil spills.
Detailed characterisation and pilot testing enabled the design of a in-situ treatment solution aimed at addressing not one contaminant plume, but three separate impacts covering an area of <0.5 hectares.
The approach incorporated Multi-Phase Vacuum Extraction (MPVE) to remove Light Non-Aqueous Phase Liquid (LNAPL) from the groundwater; pumping and chemical injection to treat residual dissolved phase contamination. Treatment targeted saturated soils and groundwater within the complex geological setting of made ground, superficial gravels and an underlying fractured schist bedrock.
This combination of techniques successfully removed all detectable LNAPL and achieved a reduction in dissolved hydrocarbon concentrations, in all areas, of greater than 95%. As a result, regulatory approval of the works was secured and the development potential of the site was unlocked.
This approach provided a cost-effective solution, incorporating not just best practice measures, but enabling the best feasible remediation process to be implemented.