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Cannon Wharf, Surrey Quays

The client:Barratt London
Services:Groundwater treatment, bioremediation, stabilisation, chemical oxidation, groundworks.

The Challenge:

The former industrial site was remediated so that it could be further developed for mixed commercial and residential development. Cannon Wharf had a long history of industrial development since 1834, leaving the site contaminated with heavy tar hotspots and PAHs from gas works waste with a potential impact on groundwater on and off the site.  Made ground was also contaminated  with heavy metals and asbestos, some fragments of asbestos embedded within the concrete slab and foundations. A number of underground storage tanks (USTs) were also present.

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The Approach

Cognition was contracted by Barratt London to remediate the site and treat contaminated groundwater in order to make the site suitable for planned construction works, high-rise residential blocks with some areas of soft and hard landscaping. The key elements of these works included; 

  •  Trial pitting and characterisation studies to delineate contamination, plan treatment, plan backfill and compaction methods;
  •  Treatability studies to determine the optimum remediation techniques for the site;
  • Excavation of hot spots and treatment of contaminated soil for re-use or disposal as non-hazardous waste;
  •  Breakout of slabs, obstructions and underground storage tanks;
  •  Groundwater treatment;
  •  Stockpiling of materials for testing and re-use under Materials Management Plan;
  • Bioremediation of TPH and PAH contaminated soil.
  • Backfill the site with treated soil, stabilisation and creation of pile mats for the construction phase of works;
  • Preliminary groundworks, including services diversions and main trunk sewer and drainage attenuation tank installation;
  • Environmental monitoring - air VOCs, air fibres, noise, vibration, water quality, groundwater;

The Outcome

Remediation works were successful and all areas met the validation criteria and the site was deemed fit for re-use by the Regulators. Soils were reused on site to reinstate to pre-construction levels. Groundwater monitoring demonstrated the site no longer posed an environmental risk. Cognition also carried out the main drainage works which enabled the construction phase to be carried out with minimal need for excavation thereby minimizing disruption and disposal.

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