Publication Summary

Ground water samples for volatile organic analysis (VOAs) were collected from nine monitoring wells and three private wells along Argonne Road to define the current distribution and concentrations of contaminants in a small alluvial aquifer east of Spokane. The suspected source is a sludge disposal area.

Ground water samples for volatile organic analysis (VOAs) were collected from nine monitoring wells and three private wells along Argonne Road to define the current distribution and concentrations of contaminants in a small alluvial aquifer east of Spokane. The suspected source is a sludge disposal area.

PERC, TCE, and cis-1,2,-DCE were detected in three of the monitoring wells (29P3, 32C4, 32M3) and one private well (32C1). The highest concentrations were detected in 29P3, which is a shallow well (~ 30 feet deep) located about 1000 feet downgradient of the sludge disposal area. PERC, TCE, and cis-1,2,-DCE concentrations in this well were 88 mg/L, 11 mg/L, and 21 mg/L in November 1995; and 90 mg/L, 17 mg/L, and 28 mg/L, respectively, in May 1996. Model Toxic Control Act (MTCA) cleanup levels were exceeded for PERC (5.0 mg/L) in wells 29P3, 32C4, 32C1, and 32M3. TCE cleanup levels (5.0 mg/L) were also slightly exceeded in wells 29P3 and 32C4.

Overall, concentrations have decreased since the detection of contamination in 1981. Although downgradient municipal wells drilled in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer have not been affected, migration of contaminated ground water to these wells continues to be of concern. To reduce contaminant loading to the SVRP aquifer, a ground water remediation and monitoring program should be designed and implemented to remove and treat the organic compounds. Periodic ground water sampling should continue.

Link to EIM data for User Study ID ARGONRD