Established in 1998, the Anaconda Regional Water, Waste & Soils (ARWWS) Operable Unit (OU) is the largest and most diverse Operable Unit in the Anaconda Smelter NPL site. As a result, the OU was separated into fifteen Remedial Design Units (RDUs) based upon factors such as location, source and type of contamination, and remedial needs. Click here for more information about the ARWWS OU.
Located northeast of Anaconda, RDU 7 – North Opportunity encompasses approximately 27 square miles and includes portions of Warm Springs Creek and Lost Creek. Land use within RDU 7 has and continues to be primarily agricultural grazing, recreation and open space/wildlife habitat. Small areas of gravel mining and crushing also operate within RDU 7, as well as the Anaconda-Deer Lodge County airport. Though limited, residential lands within RDU 7 have and will continue to be addressed in the Community Soils Operable Unit (CS OU).
Remedial designs targeted widespread areas of surface and near surface soil contamination originating from smelter fallout, as well as surface water quality of Warm Springs Creek and Lost Creek. Additionally, though groundwater monitoring of a shallow alluvial aquifer indicated overall good quality, elevated levels of cadmium were identified in groundwater in the southwestern portion of RDU 7. Areas of poor vegetation growth were also identified in the southwestern portion of RDU 7, which raised concerns regarding soil stability and the potential for erosion. Sampling data also indicated higher levels of contaminates of concern such as arsenic, cadmium, copper, lead, and zinc.
Additionally, an area of elevated arsenic levels was identified between the runways of the Anaconda-Deer Lodge County airport. This area, however, resided outside the boundaries of RDU 7. The area was designated a Facility and addressed in an Individual Site Work Plan (ISWP).
Elevated surface soil levels were abated to levels compatible with existing and anticipated future land use through the removal of surface soils and the installation of a permanent protective vegetative cover. These actions reduced the risk of human and wildlife exposure to arsenic, while minimizing the transport of contaminants to ground water, surface water or adjacent lands.
Visit the Superfund Library, located on the Arrowhead Foundation’s website, to review documents and research regarding the Anaconda Smelter NPL site. Additional information can also be found on the EPA’s website.