Remediation of the former gasworks, High Wycombe, UK

The former gasworks is on the edge of the River Wye valley, in the centre of High Wycombe, England. The site overlies gravel and chalk aquifers and there is a major public water supply well in close proximity. Gas was manufactured at the site from the 1860s until the 1960s, since when the site has been used for gas storage. The site is intended for retail/residential development. Although many MGP sites have been remediated and redeveloped successfully in the UK, this site is an outstanding case study due to the integration of numerous components of modern brownfleld remediation thinking and technology. Remediation, which is currently under way, has taken seven years of investigation, assessment, and planning. Considerations have included distinct geological changes across the site, steep topography, neighbouring residential/retail property, and proximity to a river and public water supply abstraction well. Tasks completed include phased site investigation, probabilistic groundwater risk assessment, human health risk assessment, remediation feasibility study; cost-benefit analysis (economic evaluation of societal, environmental and landowner costs and benefits); pilot trials (soil washing, bioremediation, surfactant enhanced aquifer remediation and in situ chemical oxidation); full-scale design, site clearance, implementation and validation. This case study highlights how all phases were combined in a coherent manner and with continual involvement/support of external stakeholders (Environment Agency, local government and the water utility provider). The study demonstrates how complex legacy issues, with potentially high liability, can be mitigated in a sustainable way to achieve benefit for all parties.