Case Studies of 1,4-Dioxane Releases, Treatment, and Drinking Water Contamination - Environmental Investigation and Remediation - page 366

FIGURE 8.1

Photograph of the Seymour Superfund Site in 1980, before the drums were removed.

The Seymour community experienced problems with the SRC site beginning in 1976. Residents
complained about air and surface-water discharges migrating from the site, which they blamed for
health problems. In March 1980, about 100 homes were evacuated when a reaction among incom-
patible chemicals at the site released toxic fumes that drifted into a residential neighborhood.
Following that incident, USEPA began enforcement actions at the site (USEPA, 1987). SRC had
accumulated about 60,000 55-gallon drums and 98 bulk tanks that contained waste solvents, metal
i nishing wastes, phenols, cyanides, acids, and C-56 (a pesticide by-product), as well as hundreds of
small containers of hazardous materials, primarily from laboratory operations. Some wastes were
highly explosive (USEPA, 1983). These wastes leaked and spilled from their containers, leading to
i re and odor problems, as well as substantial soil, groundwater, surface water, and sediment con-
tamination (USEPA, 1986). The site was ordered to be closed in 1978 after violating a State of
Indiana order to stop receiving wastes; the property was placed in receivership by court order in
1980, and USEPA entered into a consent decree with PRPs (potentially responsible parties) in 1982.
USEPA began removal and emergency response actions in 1980. These actions included fencing the
site and constructing runoff control dikes. Two PRPs removed several thousand drums in 1980, and
in 1981, USEPA removed chemicals from the bulk tanks and transferred those wastes to authorized
disposal sites (USEPA, 1987). By 1984, all of the drums and bulk storage tanks were removed, and
the top foot of contaminated soil was removed from about 75% of the site and also transported to
authorized disposal sites; clean i ll replaced the contaminated soil (USEPA, 1987). Figure 8.1 shows
a photograph of the site in 1980, before the drums were removed.

8.1.1 C ONTAMINANT D ISTRIBUTION AND H YDROGEOLOGY
Chemicals from the SRC site contaminated a shallow aquifer, 6-8 ft below ground, and a “deep”
aquifer, about 55-70 ft below ground, beneath a leaky silt-clay aquitard. Groundwater in the shal-
low aquifer discharges into a local creek and a drainage ditch during the wet season; in the dry
season, the creek is dry and groundwater l ows beneath the creek bed toward the nearby private
wells. Although l ows in the shallow aquifer are to the northwest, l ows in the deep aquifer are pri-
marily to the south, toward supply wells at the airport east of the site.
Sampling via monitoring wells showed that the shallow aquifer beneath the 14-acre site was
highly contaminated with more than 35 different hazardous organic chemicals. In 1985, the VOC
plume maps of the shallow aquifer showed high-concentration contamination extending about
400 ft beyond the site boundaries and trace amounts of organic chemicals as far as 1100 ft down-
gradient of the site boundary. Shallow groundwater l ow was estimated to be 400 ft/year (USEPA,
1987; Feldman, 2000).