Some of the projects now wrapped up south of Gold Hill include: the Keystone waste rock facility (WRF), which included 6.6 acres (2.6ha) of regrading and revegetation; the Hartford waste rock facility, with 3.8 acres (1.5ha) of regrading and revegetation; and the Justice surface mine, totaling 12 acres (4.9ha) and involving backfilling of the surface mine and grading to contour.

Some of the progressive earthwork activities, Comstock noted, were regrading, ripping, scarifying and dispersing growth media coverage.

"Special effort went into sloping, grading, treating and conforming the topography to natural contours," the company said. "This provides long-term slope stability, prevents ponding of surface water and minimises erosion that promotes self-sustaining, diverse and conforming native-vegetation communities."

Restoration work was performed alongside mining activities between 2013 and 2015 by contract partner Soil-Tech. The Nevada Department of Environmental Protection's (NDEP) Bureau of Mining Regulation and Reclamation (BMRR) will typically require a period of three years to evaluate and confirm revegetation success.

"New vegetation has been established and has provided tensile strength to slopes that are now stable and resistant to erosion. The new vegetation conforms to the natural surroundings and established native plants provide new habitat and ecosystems," Comstock said of the agency's feedback.

"There is no evidence of erosion, slumping or slope failure and the reclaimed areas blend in with the natural vegetation."

Corrado De Gasperis, Comstock's executive chairman and CEO, said its work with Soil-Tech was "innovative, timely, efficient and especially effective for the regrading and revegetation efforts."

He added: "We continue pushing the envelope on the development of new, clean technologies for advanced reclamation excellence, including mercury clean up and leach pad tailings reprocessing and look forward to more announcements relating to those new developments."