Statistical approach towards point sources of groundwater pollution with tetrachloroethylene: a field study.

Tetrachloroethylene contamination of well water occurred in a primarily residential area. To search for point source(s) of tetrachloroethylene contamination, 91 water samples were collected on three separate occasions from 41 shallow wells scattered in the areas. Three methods of groundwater level analysis (limited to 30 wells), cluster analysis of water quality indicators and contour drawing of tetrachloroethylene concentrations were applied. The former two analyses showed that the pollution took place in aquifers of two terraces out of the three in the polluted area. The contour mapping demonstrated the presence of three spots of suspected pollution sources as the estimated points of highest tetrachloroethylene concentrations. The available information suggested the existence of a facility with possible use of tetrachloroethylene in the past.