Tyson's Dump, a 4-acre abandoned septic and chemical waste disposal site, is located in Upper Merion Township, Montgomery County, Pennsylvania. Several formerly unlined lagoons were used to store various industrial, municipal, and chemical wastes. Spills and overflows reportedly occurred during the period of operation, thus allowing for the dispersal of wastes throughout the site. Surface water runoff and seeps contributed to offsite migration of the wastes toward the Schuylkill River. Immediate removal measures were initiated in January 1983. In December 1984, EPA issued an operable unit ROD for the onsite area. Remedial actions selected in the ROD include: excavation and offsite disposal of contaminated soils and sediments; and upgrading the existing air strips to treat leachate, shallow ground water, and surface run-on. In the fall of 1985, Ciba-Geigy Corporation (CGC) agreed to conduct a further investigation of the offsite area. In November 1986, CGC initiated an onsite pilot study using an innovative vacuum extraction technology process. In June and July 1987, four responsible parties, CGC, Smith-Kline Beckman, Wyeth Laboratories, and Essex Group submitted an alternative proposal to EPA for the first operable unit cleanup.