U.S. EPA will conduct a Removal action at the Blue Ledge Mine Site in August and September of 2006.
The Blue Ledge Mine is an abandoned copper mine situated on privately patented owned land within the Rogue River National Forest (National Forest). The Site is located approximately 3 miles south of the California-Oregon border on Road 1060. It is approximately 35 acres in size.
The Blue Ledge Mine (Site) is situated within the Siskiyou Mountain range. The mine is approximately 4,800 feet above sea level on a north slope, in close proximity to the summit (Hundhausen 1947). Approximately 4 residences, comprising the community of Joe Bar, CA, are located 1 mile downstream of the Site.
Tailings and waste rock have been dumped on the steep slopes of the Site. The waste pile may be as deep as 30 feet in some places and is estimated to be between 30,000 and 40,000 cubic yards in volume. Runoff from rainfall and snowmelt is very rapid and the potential for sheet and gully erosion of tailings and waste rock containing high concentrations of heavy metals is high. A stream course cuts down the mountainside through the waste pile.
The stream is an unnamed tributary to Joe Creek. The tributary travels approximately 1,200 feet and descends 800 vertical feet to its confluence with Joe Creek. A log tailings dam, approximately 30 feet wide and 6 feet in height, intersects the stream course, preventing the tailings and waste rock from collapsing and blocking the tributary completely. Some waste material has already penetrated the dam. The dam shows signs of significant decay and is in danger of collapse.
Stream flows do bypass the dam and surface water contact with the waste pile has resulted in acid mine drainage (AMD) and acid rock drainage (ARD) in the tributary. An orange discharge leaches from the pile into the tributary. In addition, precipitate or “yellow boy” can be observed at the confluence of the tributary and Joe Creek.
Surface water sampling conducted by the U.S. Forest Service (USFS) in September 2000, April 2001 and August 2001, documented releases of heavy metals, including cadmium, copper, iron, lead, and zinc to the tributary stream and to Joe Creek. Concentrations of cadmium and copper exceeded federal and state Maximum Contaminant Levels (“MCLs”) both in the tributary and Joe Creek. Surface water samples collected from Elliott Creek in April 2001 illustrated dramatic increases in copper, and zinc concentrations after the confluence with Joe Creek; suggesting that the Site is releasing dissolved heavy metals to the Joe Creek and that these dissolved metals are being transported to Elliott Creek.
Sampling results were also compared to Aquatic Life Criteria (“ALCs”). Cadmium, copper, and zinc concentrations exceeded their respective ALCs, at one or more sampling location, in all of the 3 sampling events.
In October 2004 USFS contacted the Emergency Response Section to evaluate the opportunity for a more aggressive response to mitigate actual releases of hazardous substances. U.S. EPA and the Superfund Technical Assessment and Response Team (START) conducted a Site screening event followed by a removal assessment at the Site. Screening samples were collected on May 4, 2005, and identified lead and arsenic as the contaminants of concern (“COCs”).
Statistical analysis of sampling results from the removal assessment indicated that the mean and 95% upper confidence limit concentration for the sample population significantly exceeded health-based benchmarks (i.e., Region 9 Preliminary Remediation Goals (“PRG”)) and background concentrations.
The U.S. EPA intends to mitigate imminent and substantial threats to human health, welfare, or the environment by taking steps to prevent the release of hazardous substances and AMD from mine tailings and waste rock to Joe Creek, Elliott Creek and their unnamed tributaries and to the surrounding environment where there is a greater likelihood of direct human contact. The removal action will include the following activities:
(1) Stabilize tailings and waste rock on steep slopes using slope stabilization techniques.
(2) Construct a sedimentation basin at the toe of the waste rock slope and above the log tailings dam. The basin will help de-energize run-off and allow metal-laden sediments to settle out.
(3) Strengthen the log tailings dam using large rocks from around the Site.
(4) Install a passive AMD treatment system.
