Leviathan Mine lies within the Bryant Creek (interstate) watershed at an elevation of 7,000 feet. The site is located in Alpine County. Approximately 265 acres of barren and eroding disturbance remain at Leviathan Mine as a consequence of mining operations. The sparsely vegetated disturbance consists of an open pit, overburden and mining waste piles. The barren conditions of the site ultimately increase Acid Rock Drainage (ARD) generation, pollutant transport, and slope instability. Low pH ARD containing high concentrations of dissolved sulfate, arsenic, nickel, aluminum and iron is discharged to Leviathan and Aspen Creeks from the channel underdrain, pond overflows and seeps. The unvegetated site has many long and steep slopes which are highly susceptible to erosion. Erosion generates sediment loads that are delivered to Aspen and Leviathan Creeks by runoff, and that threaten on-site improvements by blocking surface drainage structures.
The impact of discharges from Leviathan Mine has been sufficiently demonstrated by the continuing water quality monitoring program. Affected water bodies are Leviathan Creek, Aspen Creek, Bryant Creek, and the East Fork of the Carson River. These water bodies are listed as 303(d) impaired. The length of severely impacted water quality and contaminated sediments extend beyond the California/Nevada state line.
The site is in a remote area of the eastern slopes of the Sierra Nevada where utility services are unavailable. Evidence of vandalism is readily apparent at the site and has often required costly repairs. The area is also seismically active. Open pit mining operations created site instability evidenced by several landslides; one of these is over 100 acres in aerial extent.
Extracting minerals needed for processing more valuable ore mined in Nevada was a recurring theme. The mine had several owners and produced copper and sulfur. Initial mining efforts at Leviathan were underground. During subsurface operations Leviathan was mined for copper sulfate, copper, and sulfur, respectively. Comstock Lode miners discovered Leviathan Mine and developed the first workings in 1863. By 1869, miners became interested in the showing of primary copper minerals. In 1935, Calpine Corporations of Los Angeles began subsurface sulfur mining.
Anaconda Copper Mining Company purchased Leviathan Mine in 1951 for sulfur mining by open-pit methods. The sulfur was needed for processing copper ore at Anaconda’s Week Heights Mine near Yerington, Nevada. Isabell Construction Company began stripping overburden from the sulfur ore body in 1952. Anaconda stopped mining operations in late 1962, 13 years before the Surface Mining and Reclamation Act, and sold Leviathan Mine to Chris Mann, the Alpine County Clerk in 1963.
Approximately 22 million tons of overburden containing large quantities of low grade sulfur ore were spread over more than 200 acres without any classification, separation, or original ground surface preparation. Anaconda created a 26-acre waste dump more than 130 feet in depth by disposing waste rock, consisting of low grade ore from mining operations, in the Leviathan Creek canyon. Leviathan Creek flowed around and seeped through the waste dump. The final mined 50-acre pit was roughly 2,000 feet long, 1,000 fee wide, and a maximum of 400 feet deep.
When first looking for project funds, the Lahontan Regional Water Quality Control Board (LRWQCB) learned that, to obtain a Federal demonstration grant, the project proponent must be able to assure site access and continued project operation. From this, site ownership developed into a Regional Board objective. On December 19, 1993, Alpine Mining Enterprises deeded 23 patented load claims and the Leviathan Mill site claim to the State of California. The State Public Works Board authorized acquisition of Leviathan Mine with a resolution dated January 31, 1984 and transferred jurisdiction of Leviathan Mine to the State Water Resources Control Board in a letter dated August 20, 1984. The site is managed by the LRWQCB.
The pollution abatement project (implemented in 1986/87) resulted in extensive areas of deep compaction which prevented revegetation allowing erosion of the site to continue. Slope erosion contributes to sedimentation of the surface drainage structures constructed within the pit, around the evaporation ponds, and along the slopes below the ponds. Each year maintenance work is required to clear the surface drainage structures of sediment and to regrade and repair the dirt access roads.
Through funding from the State Water Resources Control Board Contract Agreement Number 6-076-256-0, the State of California Department of Conservation, Office of Mine Reclamation (DOC), in collaboration with the LRWQCB and the University of California, Davis, Department of Land, Air, and Water Resources (UCD), have developed a revegetation strategy for Leviathan Mine. The principal objectives of this strategy are to: (1) establish a self-sustaining native vegetative cover that will help to ameliorate degradation of water quality in Leviathan and Aspen Creeks by establishing vegetation that intercepts precipitation and controls the release of contaminated sediments and ARD, and (2) increase the evapotranspiration of atmospheric water out of the pit slopes, overburden and tailings piles by deep-rooted perennial vegetation. Soil remediation work was handled by UCD, plant-related revegetation work was conducted by the DOC, and overall management, in-kind support, and matching funds were provided by the LRWQCB.
The revegetation strategy is based on a combination of the following four components: (1) soils ripped and amended to depth, (2) site-specific plants, (3) microbial symbionts, and (4) plant protection. It is the combination of these four components that make this strategy successful and different from previous attempts at revegetation. The Office of Mine Reclamation continues to monitor test plots installed in 1997. A final report that summarizes test plot results and recommendations will be completed this year.