Saturated Soils in Elko, Nevada Mine

Case Study 

Application	Tunnel Access Stabilization	Engineer	Nilex & TenCate Geosynthetics
Location	Elko, NV	Contractor	Confidential
Product	Mirafi® H2Ri	Date of Installation (m/y)	August 2018

THE CHALLENGE 

A mine site in Elko, NV was experiencing trouble with operating equipment, specifically the tunnels spread throughout the project site. The tunnel floors were susceptible to trapping moisture, creating saturated soil which was a problematic for the mine workers and maintenance crews. It was a regular occurrence for the mine vehicles to end up stuck in the tunnels from sinking saturated areas.

THE DESIGN 

The project team had countless conquests to ultimately provide a fix in the tunnel areas. Low overhead and a constricted workspace posed an additional challenge. They tried to push large boulders which disappeared into the ground. Chemical and lime stabilization techniques were unsuccessfully deployed. During each execution, the presence of water in the tunnels was continuously noted as the primary driver to the unfavorable performance of the access roads. A TenCate Geosynthetics representative was contacted to discuss a long-term defense against the saturated soils. The moisture management, reinforcement and separation functions of Mirafi® H2Ri were the perfect combination to remedy the problematic tunnel sections. Mirafi® H2Ri was ultimately selected and a test section in one mine tunnel was installed in August 2018.

THE CONSTRUCTION

Mirafi® H2Ri was placed over the existing soils and expelled into drainage channels on either side of the mine tunnel. The 17 ft. wide roll was a perfect width to cover the roadway and no overlaps were required. Pit run gravel was placed over the H2Ri . As soon as the gravel was placed, the project team witnessed squeezing of the moisture out of the subgrade soils and into the drainage zones. Consolidation of the soils was occurring before their eyes. With more placement of gravel, the section firmed up and provided a stable base for mine equipment trafficking. Light compaction was achieved through trafficking vehicles over the placed gravel.

THE PERFORMANCE
Following the test tunnel demonstration, several other problematic tunnels were remediated with the Mirafi® H2Ri, and the moisture management system is also being deployed in new tunnel construction. The H2Ri provided a solution that granular gravel on its own, chemical stabilization and lime stabilization previously did not conquer. One year following installation, the tunnel sections with Mirafi® H2Ri were reported to be functioning as intended. Now, the mine owner spends less resources on short term fixes for these problematic areas and had provided the mine team with increased safety during daily operation of the equipment through the mine tunnels.