The Gold King Mine Level 7 Portal is located at elevation 11,436 feet on the North Fork of Cement Creek, approximately eight miles north of Silverton, Colorado.
Gold King Mine – Site Overview
After the August 2015 uncontrolled release of mine drainage, Deere & Ault Consultants, Inc. (D&A) prepared plans and specifications for mine stabilization and restoration. This included stabilizing the portal area with rock bolts and shotcrete, with backfilled corrugated steel arches in the future.
Gold King Mine Portal – After the Uncontrolled Release.
Inside the mine, D&A evaluated ground conditions and designed support. The initial support was comprised of rockbolts, mesh, and shotcrete. The final support design consists of fully lagged steel sets on a concrete foundation, backfilled with cellular concrete.
Gold King Mine – Initial Support.
A unique aspect of this project is the design of a low pressure flow control structure. This structure is needed to prevent an uncontrolled surge of mine waste and limit the flows exiting the portal to levels that can be treated by on-site waste treatment systems. Due to the existence of a nearby old portal and the fact that hydro-geologic evaluations are not complete, this structure could not be a standard mine bulkhead. It would have to be a medium term structure capable of holding back thirty feet of water head while providing machinery access through it for future work.
Construction Work Outside the Gold King Mine Portal.
The D&A design consists of a stainless steel frame with HDPE backed, removable stop logs. The stop logs include valves for water control, instrumentation, and ventilation.
During construction, D&A assisted in coordination between the EPA, surveyors, contractors, and other engineering firms.
Clients: Environmental Restoration LLC
United States Environmental Protection Agency
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