Extent and Source of Organic Solvents in Ground Water in the Argonne Road Area Near Spokane, Washington

摘要

An alluvium-filled trough cut into granite east of Spokane, Washington, contains an unconfined ground-water body that is hydraulically connected to the 'sole source' Spokane aquifer to the south. Water in the unconfined aquifer moves southward at an estimated 1.4 to 4.0 feet per day. In the spring of 1981, water in the alluvial aquifer was found to contain dissolved organic solvents tetrachloroethene, trichloroethene, 1,1,1-trichloroethane, and 1,2-trans-dichloroethene. The suspected source of the solvents is a nearby septic-tank sludge-disposal area. Solvent concentrations in at least two domestic wells in the study area have decreased with time since first detected. Data show that the organic solvents have reached the Spokane aquifer; however, the solvents were not detected in two wells in that aquifer immediately downgradient of the alluvial aquifer. The Spokane aquifer wells likely to be affected are few in number, but serve about 2,600 people.