In December of 2015, the US Forest Service determined that a mine located in Prescott National Forest required maintenance due to the potential of environmental issues. Mining operations typically create an excess of heavy metals and other materials within the remains of the excavated soils (tailings) and are stockpiled on site. Tailings and other waste rock left exposed by mining can potentially begin to spread by wind, precipitation, runoff water or wildlife, causing environmental concerns to the surrounding areas. In order to reduce the potential risk to human and ecological receptors from the heavy metals, the US Forest Service went into action to protect the surrounding area. The location was very difficult to access due to the size of the access road. The access road was 0.4 miles and had two switchbacks with only 13 feet or less radii.
The US Forest Service selected the best still available on cost, performance, maintenance and aesthetics: Concrete Cloth GCCM. The area was graded for positive drainage and long-term soil stability before installation of the Concrete Cloth GCCM. The material was then brought down the access road via excavator and a water truck was parked on an adjacent hilltop so the Concrete Cloth GCCM could be hydrated. The team then began to unroll the material overlapping it with a 4” seam working up the slope like roofing shingles. After the material had been deployed, it was then secured with 7” nails and washers on the top side of each panel, with the upper panels covering the nails to minimize uplift if soil heaves in the winter. Once the layers were secured, the team initiated the hydration phase of the installation. The entire process took only two weeks.
Even though it snowed heavily the same night after the installation was completed, Concrete Cloth GCCM remained intact, which would not have occurred with other erosion control products. Concrete Cloth GCCM also provided an aesthetic option for the US Forest Service. The contractor returned to the site six months after the initial installation to stain the material so that it would blend in with the surrounding environment. The US Forest Service was impressed with the versatility of Concrete Cloth GCCM and already has planned to utilize it for other applications including protecting geo-wrapped face walls from UV, abrasion and fires.
Application: Mine Slope
Client: US Forest Service
Location: Money Metals Mine, Prescott National Forest
Installation: December 2015
Installer: Engineering Remediation Resources Group, Inc.