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carbon neutral

Wisbech, Nene Waterfront

The client:Fenland District Council
Services:Bioremediation, stabilisation, groundwater treatment, chemical oxidation.

The Challenge:

Cognition was contracted by Fenland District Council to remediate the Wisbech site in order to reduce environmental and human health risk as to enable redevelopment to facilitate the regeneration of this area. The remediation was partly funded by East of England Development Agency, and was set up to regenerate 20 acres of river frontage in the heart of Wisbech for a variety of future uses, including residential housing commercial/industrial use. The former gasworks and industrial development site was remediated to enable redevelopment. The site was divided into 4 parcels of land (Sites, 1,2,4 & 6); Parcel 6 housed the former gasworks for the town and was grossly contaminated. Parcels 1, 2 and 3 had a long history of development including residential housing, a printing works, manure works, foundry, warehousing, a bulk fuel storage depot, coal yard, timber yard and a saw mill. Site soils were significantly contaminated with hydrocarbons and groundwater associated with the former gasworks was contaminated with TPH, including NAPL trapped within made ground and remnant underground structures.

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The Approach

The key elements of these works included;

  • Excavation, screening to remove oversize brick/concrete and segregation of made ground for further treatment;
  • In situ and ex situ Bioremediation of 30,000m3 hydrocarbon contaminated soil;
  • Groundwater treatment including NAPL removal and chemical oxidation injection;
  • Additional aeration built into the base of biopiles in Parcel 6 to aid bioremediation;
  • Desludging of remnant gasholders and demolition of structures;
  • Trials using remnant gasholder bases as bioremediation cells with materials reaching the treatment end point approximately 30% quicker;
  • Environmental monitoring and controls put in place to ensure minimal impact on neighbouring receptors;
  • Treated material backfilled and stabilised ready for construction phase.

The Outcome

Cognition successfully remediated 30,000m3 of contaminated soil materials on site to meet remedial criteria for residential use. This was stabilised and backfilled to form pile mats. The project was completed on time and to budget and was approved as a CEEQUAL project (The Civil Engineering Environmental Quality Assessment and Awards Scheme) with a score of ‘Very Good’.  The project successfully rejuvenated a large area of Wisbech enabling construction of a residential development to meet the  local housing needs.

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