Organic contamination of the Birmingham aquifer, U.K

A survey of the organic-water quality of the Birmingham Triassic Sandstone aquifer was conducted using 59 supply boreholes. Additional shallow-groundwater quality data were obtained from 15 monitoring wells. Chlorinated solvents are widespread, in particular trichloroethylene which is detected in 78% of supply boreholes. Trichloroethylene is frequently observed at high levels with 40% of supply boreholes contaminated above 30 μg/l to a maximum of 5500 μg/l. Occasional high values are also found for 1,1,1-trichloroethane and perchloroethylene. The distribution of solvents is shown to be controlled by land use and hydrogeological factors. Contamination by organic chemicals other than chlorinated solvents is low in the supply boreholes. When high contamination does occur it is usually in the form of a petrogenic hump of unresolved contaminants in the chromatogram. The source of such contamination is probably (degraded) lubricating oils. Greater contamination by general organic chemicals is seen in the shallow groundwater samples, a reverse trend to the chlorinated solvents results.