Hampton Court Gas Works, London
Background
The site, which extends to an area of approximately 2 hectares, encompasses a large proportion of the former Hampton Court Gas Works. It is to be redeveloped with 198 residential apartments, a 72 bed Nursing Home, and around 800m2 of mixed use including offices and a crèche. There will be areas of communal soft landscaping around the residential blocks. Planning conditions attached to the development require the site to be remediated so as that it is suitable for a "residential end use".
Investigation
Site investigations have been carried out by Southern Testing between 2003 and 2006. The site and surrounding area are generally flat and level being on the ancient former floodplains of the River Thames (major aquifer). Underlying geology consists of Kempton Park Terrace Gravel over London Clay. The site does not lie within a source protection zone. Analysis indicates the site is heavily contaminated with Arsenic, Cyanides, PAHs, TPH, BTEX compounds and SVOCs, largely correlating with the location of historic gas works structures. Natural soils are shown to be contaminated, although more locally. Slight to significant groundwater contamination has also been identified.
Remedial Design and Proposed Methods
Sustainable and innovative techniques have been adopted, following successful treatability studies:
- Specialist Remediation Contractor QDS will be undertaking the initial remediation work within the Gas Holders. The objective will be recovery of DNAPL from holder bases 1 and 2 using a three-stepped approach: DNAPL Flow Path Management - Optimal recovery of free product; Surfactant Flushing - To mobilise residual DNAPL; In situ Chemical Oxidation - Residual Polishing.
- Specialist Remediation Contractor Biogenie will undertake soil treatment using a multi component scheme taking into account the level and type of contamination, the environmental risk and site circumstances. Initially due to restricted working areas, bioremediation comprising of below ground biopiles will be used (insitu). These will be replaced by more traditional above ground biopiles during the later phases (exsitu).
Brownfield Briefing Remediation Innovation Awards 2008
Southern Testing were Runners Up in the Category ' Best use of a Combination of Remediation Techniques' at the 2008 Brownfield Briefing Remediation Innovation Awards for their work at the Former Hampton Court Gas Works Site.
The Judges noted that :
"the project demonstrated strong application of cutting edge techniques to a very traditional site problem and praised its design and management".
The category winners were Olympic Park Authority for the Olympic Park Project.
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