It was proposed to redevelop a former petrol and diesel filling station site with six two-bedroom flats and associated parking areas at Bridgwater, Somerset. A geoenvironmental and geotechnical investigation was carried out by South West Geotechnical Ltd (SWG) to satisfy the planning conditions of Sedgemoor District Council. The geo-environmental clean up involved:

  • Decommissioning and removal of UST’s by a specialist contractor, in line with good practice and duty of care, including:
    • Residual products were removed (bottomed) by gulper and disposed of at an appropriate waste treatment facility.
    • The tanks were flushed out with clean water to expel any explosive vapours. The resultant waste water was removed and disposed of at an appropriate waste treatment facility.
    • Tanks and auxiliary pipework were removed and disposed of at an appropriate waste treatment facility.
  • The removal of conspicuous contamination (based on visual and olfactory evidence) from around the tanks, associated pipework and other ‘hotspot’ sources.
  • Soil sampling and testing to confirm the effectiveness of the removal of contaminated soils and to check whether further excavation was necessary.
  • Waste Acceptance Criteria Testing (WAC) to classify the various wastes according to its degree of contamination and to identify an appropriate disposal site.
  • Ground water sampling and testing was carried out to assist in confirming the effectiveness of the clean-up operation.

The site remediation was a staged process, involving six phases of excavation, with each subsequent phase being directed by the interpretation of laboratory testing on samples taken during the previous phase.

The excavation and removal process was complicated by the presence of a redundant culvert choked with hydrocarbon sediment (see photo), which also had to be removed.

A validation/ remediation report documenting and recording the remediation process was prepared and submitted to the Environment Agency and Sedgemoor District Council, which was duly approved.

Former Filling Station, Bridgwater

Former Filling Station, Bridgwater