The Remediation of Chemical Groundwater Contamination at Harwell

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The Remediation of Chemical Groundwater Contamination at HarwellHGCP became fully operational in June 2007 and the original groundwater plant wasdemolished in February 2008.During 2008, HGCP was operational for over 99.5 % of the time, well above the targetfigure of 95 %. Sustained operation of the plant is required to ensure containment of thecontaminated groundwater. The closed contours around the WSA in both plots on Figure 5indicate that HGCP continues to be highly effective in maintaining hydraulic containment.The total volume of water treated by the WSA groundwater plants in 2008 was nearly480,000 m 3 (Figure 7). The total volume of water treated as a result of the WSA hydrauliccontainment operations since 1993 is now 5.6 million cubic metres.The total mass of contamination removed by the plant during 2007 was 71 kg (Figure 7), adecrease over the figure for 2007. Contaminant concentrations in the water treated byHGCP (the red lines on Figure 8) were initially higher than those for the old groundwaterplant, but have now stabilised at levels similar to those recorded in the final period ofoperation of the original plant.Overall, groundwater containment operations have removed 5.75 tonnes of contaminationsince 1993, although it is important to note that the primary role of the plant is containmentof the contaminated groundwater.The groundwater containment operation at the WSA plant forms part of a programme ofworks that UKAEA is carrying out to tackle the contamination. Other components of theprogramme include:• Excavation of the WSA chemical pits. This complex project was safely completed in2004.• Removal of contamination from the Chalk below the pits (“Unsaturated ZoneRemediation”) – see Section 4.• Enhancement of HGCP to facilitate pumping of contaminated groundwater from areasto the north of the WSA, where contaminant concentrations have reduced more slowlythan elsewhere.Operation of HGCP is regulated by the Environment Agency (EA) under the terms of aWaste Management Licence (EA WML 86165), an Abstraction Licence (28/39/18/0097)and a Discharge Consent (CAWM.0231). During 2008/09 applications were submitted totransfer these permits, and the Waste Management Licence for the closed landfill site atthe Western Storage Area (EA WML 86127), from UKAEA to Research Sites RestorationLimited (RSRL). These transfers were all successfully implemented by the EA to takeeffect from 2 February 2009, the date from which RSRL became the legal entityresponsible for these permits.LSG Groundwater Report 8 March 2009
The Remediation of Chemical Groundwater Contamination at HarwellVolume of groundwater treated (m3)500,000450,000400,000350,000300,000250,000200,000150,000100,00050,000Volume of groundwater treated in yearContaminant mass removed in year2,0001,8001,6001,4001,2001,000800600400200Contaminant mass removed (kg)0019931994199519961997199819992000200120022003200420052006200720082009Figure 7Annual quantities of groundwater treated and contaminant massremoved by the Western Groundwater Plant3500030000Old Groundwater Plant Inlet Concentration (ppb)New Groundwater Plant (HGCP) Inlet Concentration(ppb)Total VOC Concentration (ppb)2500020000150001000050000Jan-09Jan-08Jan-07Jan-06Jan-05Jan-04Jan-03Jan-02Jan-01Jan-00Jan-99Jan-98Jan-97Jan-96Jan-95Jan-94Figure 8Total contaminant concentrations in the water pumped into the WesternGroundwater PlantLSG Groundwater Report 9 March 2009
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The Remediation of Chemical Groundwater Contamination at Harwell

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