In December 1999, Response Bioremediation Ltd, a division of Response Environmental Technologies Ltd, was commissioned by the BWP Partnership Ltd, the independent consultant appointed by Clegg Construction, to provide a site-specific bioremediation strategy to remediate the Polyaromatic Hydrocarbon (PAH), Total Petroleum Hydrocarbon (TPH), and Diesel Range Organics (DRO) range of contamination within the soils at a development site in Nottingham.

The site, which formerly comprised a series of workshops, offices and storage facilities, covering an area of approximately 4.5 acres, was to be redeveloped for industrial use.

The site investigations conducted by the BWP and Waterman Environmental (representing the developer, Easter Projects) revealed ground conditions at the site generally comprising made ground/fill underlain by sands and gravels and clay, underlain by the Sherwood Sandstone. Perched water was encountered within the strata above the clay.

Hot spot areas of hydrocarbon contamination were identified throughout the site. The elevated determinands identified were PAH, TPH and DRO with maximum concentrations being recorded at 1,400mg/kg, 3,200mg/kg, and 11,000 mg/kg, respectively, to four metres depth.

In the light of the proposed industrial end-use, the fast-track construction programme and the environmental sensitivity of the aquifer underlying the site, the bioremediation strategy had to provide added value.

Following consultation with the local authority and the Environment Agency, both the bioremediation strategy and the remediation target values of PAH 1,000mg/kg, TPH 2,500mg/lg and DRO 2,500mg/kg were confirmed.

Response Bioremediation Ltd responded to the needs of the project by engineering a site-specific, risk-based, in-situ bioremediation strategy which utilised Precision Injection Technology, incorporating Response Bio-GelTM. This is a non-toxic, non-corrosive, organic, food grade substance used commonly within the food and pharmaceutical industries.

Bio-Gel is used as a carrier, an insulator and an initial source of nourishment for the bacteria used in the bioremediation of soils and water that contain elevated concentrations of petroleum hydrocarbon contamination.

Chemical analysis results after treatment confirmed that the process effectively remediated the site within a nine-week period.

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