Homestake Mine – Tunnel Closure Project
Client: Homestake Mining Company, a subsidiary of Barrick
Location: Lead, South Dakota, United States

In 2005, MES was selected as the contractor to perform the underground tunnel rehabilitation and closure of three mine tunnels in Lead, South Dakota. The shallow tunnels, located under and adjacent to residential structures and urban streets and utilities, were backfilled with cellular concrete grout to prevent future subsidence. Due to a severe regional shortage of portland cement, MES experimented with high-flyash cellular grout slurries, and developed a new mixture which exceeded the client’s specifications while allowing the project to proceed on schedule and within budget.

One tunnel underwent bulkheading and contact and formation grouting for hydrologic sealing. The grouting was performed using a circulating grout loop, using ultrafine grout materials to seal bedrock joints and the contact between the bulkhead and the adjacent rock. The grout curtain was advanced by stage drilling and progressive re- grouting.

This project required close coordination with municipal authorities and sensitivity to the residents of the nearby structures over the 3-month project duration. MES performed the grouting under the technical direction of Steven Phillips, P.E. of Phillips Mining, Geotechnical and Grouting, Inc., who was direct to the client.