Public Private Partnership
RCI assisted Comstock Mining, Inc. (CMI) with the permitting, design and construction of the relocation of approximately one-half mile of State Route 342 (SR342) and Gold Canyon Creek in Storey County, Nevada. The project was a public private partnership between CMI, Storey County, and Nevada Department of Transportation (NDOT). RCI’s responsibility included serving as the lead civil design engineer to ensure the project complied with all environmental design criteria and permit conditions, subcontractor coordination, and construction inspection.
Services Included
The RCI team was responsible for conducting a geotechnical investigation for the roadway and stream restoration, design of the cap for the mine shaft, design of two 90-foot-long, 18-foot-wide arch culverts and the stream channel itself. The stream channel design was subject to an Army Corps permit. RCI provided construction testing and inspection of all mass grading, rock cut slopes, utilities and culverts while NDOT provided construction surveying, testing and inspection of the roadway improvements including asphalt, signage, striping and guard rails.
Emergency Response
The project was unusual in two ways. First, the portion of SR342 included in the project is within a prescriptive right-of-way that is entirely owned by CMI. Secondly, the project began as an emergency response to the eminent threat of the collapse of the Silver Hills mine shaft which is located in the roadway. The shaft had a previous history of three failures in the past 40 years. Planning had been underway for the roadway and stream relocation but was in an early stage of planning at the time of the road closure in February of 2015. Complicating the project further was the approved mine reclamation plan requiring the removal of 120,000 cubic yards of historic mining wastes that underlay the stream and roadway.
80,000 Tons of Mine Waste Removed
The project team developed a plan to phase the construction so as to limit road closures as much as possible. The first phase of construction consisted of a temporary by-pass of the mine shaft area, removal of approximately 80,000 tons of mine waste and capping of the shaft with concrete. This effort required close cooperation between NDOT permitting, engineering, hydraulics, materials and right-of-way to fast track the approval of the plans. The project team expedited all aspects of the work and was able to reopen the road in early June of 2015.
120,000 Tons of Remaining Mine Waste Removed
The temporary by-pass allowed the second phase of the project to then proceed without closure of the road. The major item of work was to remove the remaining 120,000 tons of mine waste materials. Comstock Mining removed the materials using mine work forces while simultaneously constructing cut slopes and the new road embankment. All of the waste materials were required to be placed on a lined containment on the mine site due to mercury and other metal contaminants.
Roadway Relocation Project Completed in Record Time
The roadway relocation project was completed in November of 2015 after a single month of closure that was required to complete the connections of the new roadway to the existing. All in all the project was completed in 10 months, from the date of the first closure, to the reopening of the new roadway to the public. The final channel restoration required the removal of the old road which is nearing completion.
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