A PROPOSED ALTERNATIVE APPROACH TO CLEANUP OF THE ORE KNOB MINE, NORTH CAROLINA LEGACY SITE

The Ore Knob Mine is a Superfund legacy hardrock mining site situated in a rural-residential area of the Blue Ridge in upstate North Carolina. The site is a former underground copper mine at which ore was beneficiated initially by roasting and smelting (19^th century operations) and subsequently by flotation concentration (1950s). Mining-impacted areas are drained by two small perennial streams, Ore Knob Branch (OKB) and Little Peak Creek (LPC), which have been degraded by high concentrations of heavy metals, acidity, and sulfate. Seepage from a large tailings pile precipitates iron minerals that coat the substrate of OKB. These streams discharge to Peak Creek (PC), a stocked trout fishery which flows a short distance to the South Fork New River (SFNR), designated as an Outstanding Resource Water. Remedial action objectives are aimed at protecting PC and SFNR; this endpoint requires innovative solutions to technical and regulatory issues. Water hardness in these streams is very low which drives water quality standards (WQS) for many metals to low concentrations. Remediation of the two impacted streams will rely on source control and passive treatment measures. Because these technologies may not achieve all applicable WQS, EPA and the State have discussed options to protect PC using an effluent-based approach for OKB that would not require strict adherence to WQS. LPC, which is less contaminated, is expected to meet WQS except for the upper reach where impacts are more severe; this reach could optionally be assigned biological integrity goals. This regulatory approach would allow flexibility in developing cost-effective remedial strategies to protect sensitive receiving waters under an adaptive management strategy.