PRIORITIZATION OF CONTAMINANT SOURCES FOR THE SCHUYLKILL RIVER SOURCE WATER ASSESSMENT

The Schuylkill River Source Water Assessment Partnership is performing source water assessments of forty-two public water supply intakes for the Pennsylvania Department of Environmental Protection. The watershed encompasses a land area in excess of 1900 square miles with more than 3000 potential point sources of contamination. In addition, run-off from diverse land uses such as urban and agriculture must be characterized. This paper discusses the overall approach used to screen and evaluate the thousands of potential sources within the Schuylkill River watershed for a single intake. An important component of the approach was the use of decision support software for equitable evaluation of the relative impact of point sources, run-off, and spills on the drinking water supplies.EVAMIX is the decision support software used for the Schuylkill River Source Water Assessments (Voogd, 1983). The greatest benefit of EVAMIX, compared to other software, is that it allows mixed criteria evaluation – qualitative and quantitative – to be considered concurrently. The tool was a critical component in handling the numerous sites in an equitable manner. EVAMIX uses pair-wise comparisons of normalized criteria to develop a relative ranking of alternatives. For the source water assessments, the alternatives are the potential contamination sources. Criteria include such quantitative items as time of travel and mass loading and qualitative items such as potential for release, location in flood plain, and potential impact based on toxicity and treatability.The assessment included both point sources and run-off, and evaluations were performed for an overall priority of potential sources, as well as for priority lists for ten different contaminant categories of concern in drinking water treatment.