Abstract

We investigated the hydrogeologic behavior of the United States Antimony Corporation's 1O-acre waste impoundment. We found that waste fluids from the impoundment contribute measurable concentrations of antimony, sulfate, and sodium to the underlying ground water system. The concentrations and transport of these contaminants are strongly influenced by large fluctuations in the water table beneath the disposal impoundments. Water table fluctuations are, in turn, driven by seasonally variable ground water recharge from Prospect Creek.

Prospect Creek carries a measurable dissolved antimony load attributable to the impoundment site. We found this flux to be maximized under high spring streamflow conditions. Under the conditions studied, the discharged antimony is unlikely to significantly degrade the mainstem Clark Fork River. However, we have estimated the impounded wastes contain up to 100,000 pounds of water- soluble antimony, and under the existing hydrologic conditions they will continue to provide the alluvial ground water system and Prospect Creek with a low-grade source of this metal.

Start Date

19-4-1985 12:00 AM

End Date

19-4-1985 12:00 AM

Document Type

Presentation

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Apr 19th, 12:00 AM Apr 19th, 12:00 AM

Transport of Antimony Processing Wastes in the Prospect Creek Drainage, Western Montana

We investigated the hydrogeologic behavior of the United States Antimony Corporation's 1O-acre waste impoundment. We found that waste fluids from the impoundment contribute measurable concentrations of antimony, sulfate, and sodium to the underlying ground water system. The concentrations and transport of these contaminants are strongly influenced by large fluctuations in the water table beneath the disposal impoundments. Water table fluctuations are, in turn, driven by seasonally variable ground water recharge from Prospect Creek.

Prospect Creek carries a measurable dissolved antimony load attributable to the impoundment site. We found this flux to be maximized under high spring streamflow conditions. Under the conditions studied, the discharged antimony is unlikely to significantly degrade the mainstem Clark Fork River. However, we have estimated the impounded wastes contain up to 100,000 pounds of water- soluble antimony, and under the existing hydrologic conditions they will continue to provide the alluvial ground water system and Prospect Creek with a low-grade source of this metal.