Abstract

This paper presents the findings of the ground-water quality assessment in the vicinity of the industrial waste lagoon at Tooele Army Depot, Utah. The industrial waste lagoon was an unlined evaporation pond which received industrial waste water generated by maintenance activities at Tooele Army Depot. Waste water leaking from the IWL contributed a large volume of trichloroethene and other organic contaminants to the ground-water system.

Tooele Valley, in which Tooele Army Depot is located, is an alluvium-filled valley within the Basin and Range physiographic province in Utah. Ground water occurs in an alluvial aquifer composed of several thousand feet of unconsolidated sediments of Tertiary and Quaternary ages. A bedrock aquifer composed of quartzite and limestone beds of late Mississippian, Pennsylvanian, and early Permian ages also occurs within the study area. Ground water occurs between 400 feet and 170 feet below ground at Tooele Army Depot.

The ground-water cleanup planned for Tooele Army Depot includes two components: (1) elimination of the source of contaminants by closing the industrial waste lagoon and waste water ditches, and (2) extraction and treatment of contaminated ground water. The most highly contaminated soil will be excavated from the waste-water ditches and placed in the industrial waste lagoon where it, along with contaminated soil and sludge from the industrial waste lagoon, will be covered with a multi-layer cap. Ground water will be extracted from wellfields located at the waste-water ditches and at the northern Tooele Army Depot boundary, treated with air strippers, and returned to the aquifer through injection wells. It is anticipated that the contaminated ground water will be circulated several times through the extraction/treatment/injection systems before it will meet the cleanup levels approved by the Utah Solid and Hazardous Waste Management Committee.