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carbon neutral

Newbury Gas Works

The client:Nelson Land LTD and PSP Consulting
Services:Demolition, bioremediation, chemical oxidation, stabilisation/solidification, permeable reactive barrier and clay cut-off wall installation, fabric extraction system to remove NAPL.

The Challenge:

Newbury Gasworks site, within the Sterling Industrial Estate, has had a long history of industrial use leaving a heavily contaminated site within a built up area of Newbury surrounded by residential and commercial properties. Stringent environmental monitoring was therefore required to ensure minimal impact on the local environment. A main line railway line on the southern boundary of the site meant works had to be carried out under strict asset protection agreement  with Network Rail. Demolition was also required of a redundant building adjoining an operational office/workshop commercial  industrial past meant that remediation was essential and several approaches were required to decontaminate the site to meet regulatory approval.

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The Approach

Cognition was appointed by Nelson Land and PSP Consulting to remediate the site to reduce environmental and human health risk and enable redevelopment to Residential Apartments with Basements. The key elements of these works included:

  • Implement a strict regime of environmental monitoring, local liaison and network rail asset protection planning;
  • Breakout, removal and processing of concrete on site to a re-usable aggregate;
  • Pumping, desludging, removal and decommissioning of historical underground storage tanks and gasholders;
  • Demolition of redundant industrial unit on the site.
  • Installation of a 360m Permeable Reactive Barrier (PRB) on the site perimeter to absorb free phase contamination and prevent the spread of residual contamination off site to protect the chalk aquifer;
  • Both permeable and impermeable PRB sections were driven and mixed in-situ using a specialist piling rig;
  • Removal of residual Non-aqueous Phase Liquids (NAPL) using a oleophilic fabric extraction system which targets and absorbs/desorbs NAPL, avoiding the need to treat significant volumes of groundwater;
  • Ex-situ and in-situ treatment of highly impacted soils using cement stabilisation/solidification, reducing leachability of the soil material;
  • Treatment of residual contamination within saturated soil at the base of excavations using an Oxidation Reactive Compound (ORC).

The Outcome

Cognition successfully remediated 17,000m3 of contaminated materials on site to meet remedial criteria for residential use. This included the removal of NAPL to <5mm thickness on groundwater interface by deploying the fabric extraction system . A protective PRB wall around the site will protect against potential off-site contamination migration. The works were carried out with minimal disruption to local residents.

One of the key successes was the liaison with the residents and regulators from inception through to completion. Cognition endorsed regular visits from both the Local Authority and Environment Agency throughout the works. Regular newsletters issued to the local community provided details of anticipated site works and progress. This was commended by regulators given that the site was overlooked by many properties. The scheme had been many years in planning and the successful remediation has formed an outstanding first stage in this highly-publicised development.

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