The B&C Smelter site is located centrally in the Town of Alma on North Main Street, adjacent to the Town Hall. This time-critical removal action involved the removal and the covering of contaminated soil and slag with lead concentrations greater than 400 mg/kg that are associated with the former B&C Smelter site.
Lead, the primary contaminant of concern at the Site is a listed hazardous substance as defined by Section 101(14) of CERCLA and 40 CFR 302.4. Historic smelting activities conducted at the Site have resulted in hazardous substances (lead as high as ten times residential regional screening levels of 400 mg/kg) being released into the surrounding environment, contaminating residential soils and area drainages. The initial site estimated of 2,000 cubic yards of mine-related slag piles and 3,000 cubic yards of contaminated soils, primarily at surface or near-surface locations and adjacent to town structures and recreational areas were under estimated. Due to the volume and depth of the lead contamination waste, a protective layer of clean backfill and topsoil will be placed on top of any waste left onsite. The topsoil has been hydroseeded to stabilize the area. The removal action commenced on November 12, 2019 and was completed on 7/23/2020.
The waste was loaded into trucks and hauled as non-hazardous, Bevill-exempt, solid waste for treatment at the London Mine and beneficial use in the Mine's engineered repository. The slag/waste was mixed with tailings, residuals from the London Mine water treatment plant, and lime which will initiate a pozzolanic reaction to stabilize and solidify the wastes. The result is a solidified aggregate material with reduced leachability of the heavy metals. Any long-term maintenance of the solidified material and the engineered repository will be conducted by the owner of the London Mine and overseen by the Hazardous Materials and Waste Management Division of the Colorado Department of Public Health and Environment. The Bevill Amendment (section 3001(b)(3)(A)) exempted waste from the extraction, beneficiation, and processing of ores and minerals. For more information on the Bevill Amendment go to https://www.epa.gov/hw/special-wastes.
