Project Description:

This historic silver, lead, and zinc mine complex was mined actively  from  1875 to the 1880´s and consisted of over 125 patented and unpatented mining claims and 40 mill site locations. After World War II, the properties were acquired by the Anaconda company and the mine became one of the leading lead producing mines in the western U.S.

The working are represented by shallow open cuts,, thousands of feet of subsurface workings, mill tailings and waste rock piles. Currently, the majority of the mill tailings are located on BLM lands adjacent to the patented mining claims. Many historical buildings are still preserved on the patented mining claim portions of the site. Historically, the milling operation was located one of the patented claims on the west slope of the Darwin Hills, but the ore milling equipment and building have since been removed. The mill tailings are the only observable evidence of the size and magnitude of the mining operations.

Previous/Existing Assessments:

A preliminary site inspection was undertaken during Spring 2006, when elevated concentrations of lead, zinc, and arsenic were detected in the mill tailings material. This survey was followed up by a detailed investigation during Fall 2007. The results of this latter investigation were included in the CERCLA Removal Site investigation document. A CERCLA draft Engineering Evaluation/Cost Analysis (EE/CA) document was compiled by Fall 2009 by an environmental contractor.

Historically, the mill tailings were dumped onto the steep slopes on the west side of Darwin Hill and flowed into an impoundment that was constructed adjacent to Lucky Jim Wash. Over time, a substantial portion of the mill tailings wastes were washed downstream into Darwin Wash.

Reclamation/Recommendations:

• The remediation plan entailed capping excavation, consolidation, of mill tailing wastes.
  Specifically, The Engineering Evaluation/Cost Analysis (EE/CA) document several alternative or options have been  proposed for remediation of the tailings, including capping and transport of a minor amount of tailings material.
• The tailings capping proposal would minimize runoff into the adjacent wash during storm events as well as minimize air-borne transport of lead particulate material into the adjacent town of Darwin.
• The capped mill tailings would be recontoured with native soil and then reseeded with native plants.
• A post-remediation monitoring and sampling program would be implemented to determine effectiveness of remediation efforts.

Risk:  Water quality, Lead, zinc and arsenic contamination

Location:  Section 13, 14, 23, and 24, T19S, R40E, Inyo County California

Field Office:  Ridgecrest

Congressional District:  25