USE OF GROUNDWATER AGE INDICATORS IN RISK ASSESSMENT TO AID WATER SUPPLY OPERATIONAL PLANNING |
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Authors: | B. Morris MSc M. E. Stuart BSc CChem MRSC W. G. Darling PhD D. C. Gooddy PhD CChem MRSC |
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Affiliation: | Principal Hydrogeologists, British Geological Survey, Wallingford, Oxfordshire, UK.;Senior Geochemists, British Geological Survey, Wallingford, Oxfordshire, UK. |
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Abstract: | Groundwater residence-time survey results on 21 public water supplies in the chalk aquifer in southern England are compared with a previous Cryptosporidium risk assessment which was carried out on the same supplies for regulatory-compliance purposes in 1999. The results indicate that residence-time indicators could provide useful corroborative evidence for rapid recharge hazard - not only in those settings already identified by microbiological surveillance, but also in the more difficult-to-identify situation where potential rapid pathways have been identified but the bacteriological indicators are negative or ambiguous. However, groundwater-mixing processes under pumping conditions are complex, especially in the chalk, and will always require interpretation informed by an understanding of the local hydrogeological and operational setting. |
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Keywords: | Chalk hydrogeology chlorofluorocarbons Cryptosporidium groundwater Indicators risk assessment |
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