WSP GROUP has used a combination of conventional and insitu remediation methods to clean up a former MoD Defence Evaluation and Research Agency site in Farnborough.
Two of the firm's subsidiaries, WSP Environmental and WSP Remediation, carried out the work for client Slough Estates which will develop the site as a business park.
The 50ha site was used primarily for aircraft design and manufacture and aviation research. A variety of potentially contaminating operations were carried out, including handling and disposal of chemicals, maintenance and refuelling of aircraft and road vehicles, handling and use of explosive ordnance and radioactive materials and storage and use of fuels.
WSP Environmental carried out investigation and risk assessment before Slough Estates bought the site, to confirm ground conditions and evaluate the cost implications of remediation.
While contamination was not widespread, investigations revealed that several areas needed remediating.
After site purchase, WSP Remediation was awarded the contract to specify and design the remediation, obtain regulatory authority approvals, provide remediation contract services and certify and validate the works.
The main aims of remediation were to deal with contaminated areas that would cause problems for development and environment and to minimise requirements for off-site disposal.
Areas of made ground containing asbestos cement sheeting, glass, ceramics, wood and metal contamination that were not treatable on site were first excavated and removed to licensed landfill.
An insitu vacuum enhanced product recovery pumping system was then used to remediate an area of the site used for hydrocarbon fuel storage and distribution which included a plume of gasoline contamination up to 2m thick on the groundwater table. WSP Remediation designed and installed the system after modelling the capture zone for the well network.