An Engineering Evaluation/Cost Analysis was completed for the US Forest Service (USFS) for removal and cleanup activities under CERCLA at the Zaca Mine Complex, an abandoned underground gold and silver mine located in Alpine County, California, in the Humboldt-Toiyabe National Forest. The objectives of removal and cleanup activities were to improve water quality in adjacent creeks by reducing discharge of acid mine drainage (ARD) to surface water; provide for the viability of native plant and animal species; protect and restore aquatic, riparian, and meadow systems; and restore degraded ecosystems and processes.

VESTRA prepared final design documents for removal actions under CERCLA for identified abandoned mine features in the Colorado Hill Watershed. The project entailed final design documents for the abandoned mining features at the Lower Advance Adit, Lower Colorado Adit, Zaca Tailings, Lovestedt Tailings, Loope Canyon Well, Loope Canyon Adit, Deadman Adit, and Curtz Mine; design of collection and infiltration galleries as a means to reduce the discharge of ARD to creeks; removal and/or regrading of existing tailings piles adjacent to creeks, including regrading and placement of topsoil to reduce erosion of the tailings into Monitor Creek; and regrading the existing tailings pile, covering with topsoil and revegetating, as well as relocation of an existing wetland.