Ground water is the principal source of drinking water in the vicinity of the Ciba-Geigy Superfund site near Toms River, Ocean County, New Jersey. The presence of earlier identified point sources of organic-compound and, to a lesser extent, metals contamination dt the Ciba-Geigy Toms River Chemical Company Plant has resulted-in severe degradation of ground-water quality and has increased the potentiil for water-supply problems (NUS Corporation, 1988). The point sources of contamination include a manufacturing area, a backfilled-lagoons area, a former fire-prevention training area, several sludge-disposal areas, and a drum-disposal area. A borrow area also is considered a potential source of contamination (Camp Dresser 6 McKee, Inc., 1989). The U.S. Environmental Protection Agency requested that the U.S. Geological Survey evaluate the hydrogeologic conditions in the Kirkwood- Cohansey aquifer system (Zapecza, 1989) and the extent of ground-water contamination on the property of the plant (which includes the Superfund site) and in Winding River Park, which borders the Toms River immediately to the east of the Superfund site (Barton, 1989). This investigation included an electromagnetic-induction survey covering 45 line miles throughout the site and a ground-penetrating-radar survey in part of the borrow area. The quality assurance/quality control plan (QA/QC) for the electromagnetic-induction survey established guidelines for performance, system audits, and data validation, and set control limits for instrument and procedural precision. The QA/QC plan for the groundpenetrating- radar survey sets guidelines for performance and system audits.