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Island Point

23 November 2017

Chalegrove Properties Limited appointed Cognition to carry out remediation works on a former industrial site located in London.

Chalegrove Properties Limited appointed Cognition to carry out remediation works on a former industrial site located in London.

Planning permission was obtained to develop the land into residential use, providing 173 residential units.

The site was identified by previous ground investigations to have shallow made ground present, which contained elevated levels of heavy metals, with TPH impacted areas underlying the hardstanding, associated with previous industrial use.

There were also 2 large mounds of fly tipped material comprising soils, brick, metal and concrete present on the site. These materials were found to be generally inert in nature; further chemical analysis was undertaken by Cognition to ensure suitability prior to re-use

The works completed by Cognition comprised carrying out remedial works in order to reduce and mitigate potential risk to future site users and to the underlying Secondary and Principal aquifers.

The remediation works included:

Removing all hardstanding across the site, along with underground obstructions from former buildings; these materials were segregated and stockpiled for off-site recycling.

The spoil heap soils were found to be chemically suitable for re-use; the material was screened and processed to remove unsuitable materials such as brick, wood, metal and concrete etc. prior to re-use on site to ensure that the material was physically suitable for re-use.

The made ground soils across the site were stabilised in-situ to form a pile mat, for use in the future development, the stabilisation process also acts to immobilise and solidify potential contaminates in-situ, therefore eliminating risk to on-site receptors.

The TPH hotspots were targeted by Cognition using pump and treat and bio-remedial methods. The free-phase TPH was pumped from two newly installed designated treatment wells within the groundwater plume, through a mobile groundwater treatment plant comprising; activated carbon, an oil/water separator and sand filter to remove free-phase TPH.

The TPH impacted soils were excavated and treated ex-situ within bio-piles using bioremediation methods comprising mixing ORC-A (oxidising agent) and additional bacteria to help speed up the remediation process, prior to re-use of the materials on site.

Validation testing was undertaken on the excavated TPH impacted areas and during pump and treat/ bio-remedial treatment.

Groundwater monitoring and sampling is continuing post remediation works by Cognition, to ensure and confirm successful remediation of the groundwaters within the TPH impacted plume area. 

Untitled.jpg ip1.jpg ip3.jpg ip5.jpg Ex-situ bioremediation of TPH impacted material
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