Gilt Edge Mine Access Road and Cell Construction

Harsh weather conditions in the Black Hills were no match for our team, who completed this project with zero injuries, zero recordables, and zero non-conformance reports.

The 360-acre Gilt Edge Superfund Site, an abandoned, open-pit cyanide heap leach gold mine first mined in 1876, was developed in highly sulfuric rock. Located in the Northern Black Hills southeast of Deadwood, South Dakota, the site was added to the EPA’s National Priorities List in 2000 at the request of the state. To prevent surface water from interacting with acid-generating materials and reduce the amount of acid rock drainage on site, acid-generated mine wastes had to be excavated, consolidated into mine pits and covered. Substantial earthwork, regrading, and improved water diversion and drainage structures were required.

As part of this project, we moved over 106,500 cubic yards of HWY 385 material from the site’s Cell G footprint, which was then screened to 1-inch minus material. Cell G was constructed using 40,000 cubic yards of spent ore, which was located below the relocated HWY 385 material.

Our team also constructed the North Access Road, which required blasting of over 12,000 cubic yards of rock for road construction and a pipeline installation corridor. Over 80,000 cubic yards of shot rock and overburden were used for cut and fill to construct the access road.

The pipe corridor was constructed parallel to the road and down to a nearby pump station at the Ruby Repository. We installed more than 31,000 linear feet of HDPE pipe from the Ruby Repository to the Anchor Hill pit, along with clean-out reservoirs, valves, and ten structures.

Despite project delays caused by the harsh weather conditions, the project was completed successfully, safely, and without incident.