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Tipner, Portsmouth

The client:South East England Development Authority (SEEDA)
Services:Bioremediation, segregation, groundwater treatment, soil washing, stabilisation, chemical oxidation, PRB.

The Challenge:

The 1.7 hectare former PD Fuels Depot at Tipner formed part of the 44 hectare Tipner Regeneration Project that would transform the geographical area and provide a new gateway to Portsmouth. The site was located in a sensitive busy residential area adjacent to Tipner Lake, an SPA, Ramsar Site and SSSI designated tidal water body interconnected with Portsmouth Harbour. The site was heavily contaminated with a range of pollutants including TPH, PAH, SVOCs/VOCs and asbestos due to historic industry including a fuel depot, tar works and timber yard leaving the site contaminated.

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The Approach

Cognition was contracted by SEEDA to remediate site soils and groundwater in order to reduce the health risk to future residents. The key elements of these works included;

  • Remediation trials investigating a range of treatment options including Soil Vapour Extraction (SVE), Multi-Phase Extraction (MPE), soil washing, chemical oxidation, soil stabilisation/encapsulation and permeable reactive barriers;
  • Detailed studies investigating several bioremediation additives;
  • Concrete slabs broken out and trial pits excavated to delineate contamination;
  • Excavation, chemical testing and delineation of contamination;
  • Ex-situ bioremediation using cultured indigenous bacteria, biosurfactants, soil enhancers and nutrients;
  • Additional chemical additives applied to soils with a high BTEX concentration;
  • Groundwater and surface water treatment;
  • Pre-processing/screening of soil;
  • Soils stabilised prior to backfill and compaction with upper layers forming piling mats;
  • Environmental monitoring and controls put in place to manage dust and odour;
  • Clean capping installed across site to protect workforce during construction phase.

The Outcome

Cognition processed 80,000m3 of soil with 30,000m3 successfully bioremediated to meet the agreed re-use criteria and backfilled. Other remediation techniques such as groundwater treatment and a PRB were employed on the site to aid remediation. Treatment and re-use delivered significant savings over conventional disposal, as well as other benefits such as reducing site traffic and disruption in the local area.

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