The Oval - Remediation of a Former Gas Holder Site

8 November 2021

Cognition Land and Water has been contracted by Wooldridge Demolition to carry out the removal of former gas holder bases at Oval Village, Lambeth to make way for redevelopment of the site by Berkeley Homes.  Apart from the complex groundworks and temporary works to enable the removal of the former gas holder bases, Cognition’s work includes for the removal of contaminated sludges, dewatering and treatment of the gas holder contents. 

As of the end of October 2021, our work on the project has included: 

  1. Pre-start supplementary site investigation, water sampling and site characterisation to enable finalisation of the Remediation Implementation Plan.
  2. Agreement and approval of the Remediation Implementation Plan and Mobile Plant Permit with the local authority and Environment Agency.
  3. Mobilisation to site and installation of water treatment plant
  4. Dewatering of gas holders 1,2,4 and 5
  5. Desludging of gas holders 1,2,4 and 5 

The work remaining for Cognition to complete includes: 

  1. Disposal of contaminated sludge and discharge of treated waters in accordance with waste duty of care and discharge consent.
  2. Recirculation of treated water.
  3. Completion of Remediation Verification Report for the works completed by Cognition Land and Water. 

The Water Treatment Plant (WTP) provided for this project is for the treatment of gas holder water to allow for its safe discharge to sewer.  The system comprises an inlet tank, primary particle filtration, buffer tank followed by turbidex filtration and carbon filtration.  

Through careful management of the works, open and regular communication with the whole project team and application of robust yet dynamic quality and management systems, the project is running on time, to budget and to the high-quality standards expected by our client and the whole project team.  Cognition has maintained a strong and positive working relationship with the client and the wider project team throughout. 

Shortly, Cognition will be embarking on the most complex and challenging stage of the project due to the depth of Gas Holder 1 dumpling and base being some 13 metres below ground level.  A rigorous and tried-and-tested works sequence has been prepared by our experienced team and we are confident that our expertise and problem-solving approach will result in the successful completion of the works.

If you want to know more about the work Cognition is carrying out at The Oval or has completed on many other gasworks and gas holder sites, please contact: