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Permeable Reactive Barrier installation

1 November 2018

Cognition was appointed by Nelson Land and PSP Consulting to remediate the Sterling Industrial Estate, Newbury. 

Cognition was appointed by Nelson Land and PSP Consulting to remediate the Sterling Industrial Estate, Newbury. Remediation at the site was essential to remove the historical infrastructure associated with the former Gas Works and industrial estate. Due to the significant industrial past at the site as well as use as a gas works, several remediation approaches were required to decontaminate the site to meet regulatory approval. Techniques employed included:

Installation of Permeable Reactive Barrier (PRB) to the top of the chalk aquifer approximately 6m below ground level. Both permeable and impermeable PRB sections were driven and mixed using a specialist piling rig. The purpose of the barrier is to treat any residual subsurface contamination that has the potential to migrate off-site.

To remove any residual Non-aqueous Phase Liquids (NAPL) at the site, Cognition deployed a NAPL fabric extraction system which targets NAPL from the groundwater using an oleophilic/hydrophobic fabric. The key advantage of the technique is that is only extracts NAPL negating the need to pump and treat huge volumes of groundwater.

Highly impacted soils at the site were treated using cement stabilisation/solidification. Cognition successfully demonstrated the re-use of materials on the site by effectively reducing the leachability of material following stabilisation. To demonstrate the effectiveness of remediation extensive tank trials and validation testing was undertaken on an on-site laboratory.

In accordance with the remediation strategy, any residual contamination at the base of excavations was treated using Oxidation Reactive Compound (ORC). Cognition applied specific doses of the compound dependant on the concentrations of hydrocarbons encountered in base sample.

Breakout, removal and processing of all concrete on site to a re-usable aggregate.

Removal and decommissioning of historical underground storage tanks and gasholders.

Formation of pile mats to enable the construction stage of the project.

One of the key successes of the scheme 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. Cognition also issued regular newsletters to the local community to provide details of anticipated site works and progress. This was commended by the regulators overseeing the project given that the site was significantly 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.

2.jpg NET 1.png Fabric Extraction System R1.jpg Installing the PRB n2.jpg
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