Projects by Discipline / Environmental Science

Penn Mine Drainage Evaluation

The Penn Mine is an abandoned underground copper mine that operated from 1860 until 1953. The Penn Mine property is located in central California within the Mokelumne River watershed adjacent to the Commanche Reservoir. The Mokelumne River supports a salmon fishery and represents an important source of municipal and agricultural water supply.

A mixture of subsurface drainage and surface water runoff from the mine has produced substantial amounts of heavy metals-laden acid mine drainage which have historically flowed into Commanche Reservoir and the Mokelumne River.
The East Bay Municipal Utility District (EBMUD), which owns Commanche Reservoir, constructed a small dam, diversion facilities, and acid drainage retention ponds at the mine site in an effort to minimize contaminated discharges from the site. However, these facilities actually caused additional pollution because they were constructed of acid-generating materials and they did not have sufficient capacity to prevent major spills. A pollution abatement and clean-up effort for the mine has been ongoing under the jurisdiction of the California State Water Resources Control Board and the U.S. Environmental Protection Agency pursuant to the Federal Clean Water Act and the California Toxic Pit Control Act.

Hydrosphere was retained by the Committee to Save the Mokelumne River to provide expert testimony in the areas of hydrology, geochemistry, and hydrogeology in litigation before the Federal District Court, Eastern California District, regarding the adequacy of EBMUD's abatement measures.

Hydrosphere's efforts focused on evaluating the probability that: (1) the short-term abatement efforts for the Penn Mine site as proposed by EBMUD would be sufficient to prevent additional discharges from the mine site over the ensuing winter months, which constitute the wet season in that area; and (2) the dam and the retention ponds were adding pollutants to the site.

Specifically, Hydrosphere:

• Developed statistically-based rainfall-runoff relationships for the mine site watershed based on historical local climate data
• Investigated the capacities and physical conditions of the existing drainage control facilities at the mine and evaluated their ability to capture various runoff events combined with subsurface drainage
• Reviewed the proposed short-term abatement measures and assessed the environmental benefits, if any, resulting from their implementation
• Analyzed the costs and benefits of continued on-site treatment of all acid mine drainage produced at the site
• Evaluated the acid-generating potential of the material used in construction of the dam and the drainage retention ponds
• Determined whether the material was adding pollutants to water in the reservoir and retention ponds at the site
  

Hydrosphere's expert testimony was relied on extensively by the District Court in its decision in favor of the Committee to Save the Mokelumne River.