DBS have recently supported an industrial client with contaminated land due diligence for the purchase of a commercial site in Tyne and Wear, as part of the due diligence process our brief was also to provide documentation for the Local Planning Authority to enable planning conditions for contaminated land to be discharged, for a change of land use.
Our client is proposing to redevelop the site for a new industrial development comprising a waste management facility.
The site was located close to dockland, and had been in use in the war years for the storage of oils and petroleum. There were large above ground storage tanks located across the site from the 1800s to the 1940s, which presented a significant potential to acquire liabilities from this historical usage, as the site is located above a Principal Aquifer.
We completed a highly targeted investigation of the subsurface across the site, with each former tank base location being located using GPS and a programme of drilling implemented using window sampling techniques.
Window sampling was the preferred method as it provided easy access to the existing buildings on the site that the client was looking to purchase, and a corer could be used to penetrate the existing slab, whilst leaving discrete holes that could be restored if the client decided not to proceed with acquisition.
A series of boreholes were sunk across the site, with selected boreholes installed with combined gas/groundwater wells, and samples of soils and groundwater’s taken for laboratory chemical analysis. A PID was used throughout the works to assess vapour/hydrocarbon potential, and all samples were subjected to headspace testing at the end of each working day.
The work confirmed the presence of hydrocarbons in the subsurface, but this was limited to highly weathered product that was found to be sitting on top of the underlying Glacial Till, beneath the existing floor slab. The hydrocarbon material had not impacted the shallow groundwater regime, and, it had not migrated vertically within the soil profile.
A programme of gas monitoring post completion did not identify a ground gas risk from off site sources of ground gas (landfill), or, from VOCs.
Comprehensive risk assessments were undertaken for human health, controlled waters and ground gas, and our final report allowed our client to progress the acquisition of the site knowing they were not potentially taking on liabilities, and, provided the required information to support their planning application for a change of land use.
We successfully achieved full condition discharge from the LPA in February 2015, and the site is now being taken forward for its new use, and providing jobs in the region.