Not All Contamination Comes from Mining Operations

Abstract

The former International Smelter & Refining Company smelter (IS&R) produced copper, lead and zinc for 70 years. The site was listed on the NPL in July 2000. One of the Agency concerns was that the smelter was responsible for elevated nitrate and arsenic concentrations found in wells at a nearby town. The groundwater conceptual model provided the methodology for determining potential impacts from the IS&R operation. Historical records, geologic/hydraulic characteristics, and groundwater flow direction were investigated during the Remedial Investigation (RI). Potential contaminant sources included smelter process operations, smelter site waste material, and mine dewatering. The investigation used MODFLOW modeling to determine flow direction and rate, cation and anion concentrations and stable isotopic composition to develop groundwater signatures, and NETPATH to determine groundwater evolution. The analysis concluded that water  from town wells consists of a different chemical signature and comes from a separate source than water flowing below the smelter site.

Anderson, S.D., P.E., K.B. Cosper, P.E., B.W. Buck, P.G., A.M. Lemon, A.L. Mayo, PhD, P.G., 2004 Tailings and Mine Waste Conference, Colorado State University, Fort Collins, CO, October 10-13.