URBAN GROUNDWATER POLLUTION - A CASE-STUDY FROM COVENTRY, UNITED-KINGDOM

A regional ground-water quality survey from 28 wells in the Coventry a rea of the United Kingdom identified widespread ground-water pollution . Chlorinated hydrocarbon solvents (CHSs) were detected at concentrati ons exceeding 1 microgram per liter (mug/l) in all industrial and publ ic water supply wells within the urban area. Of the CHSs analyzed, tri chloroethene was most ubiquitous and was also detected at the highest concentrations, reaching a maximum of 547 mug/l at the industrial ''Si te A'' during this study. By comparison with CHS pollution, inorganic and trace element concentrations were elevated relative to assumed bas eline levels only in some industrial wells. The limited extent of inor ganic contamination may be due to (1) retention of pollutants within t he unsaturated zone, (2) ground-water mixing in wells, (3) ferric hydr oxide precipitation resulting in heavy metal coprecipitation, and (4) sorption on sand grains coated with ferric hydroxide. For inorganic de terminants, a pollution index was devised which ranked zinc and boron as primary indicators of inorganic contamination. Regionally, concentr ations of CHS and inorganic determinants did not reveal any significan t correlation with depth.