Unique Water Control Grouting in Deep Multilevel Marble Mine
Active mining in an eight-level underground marble mine was separated from a valuable area of additional reserves by a set of vertical fractures. Previous attempts to mine access to the reserve base failed due to high-pressure water inflows. Cementitious grouting efforts failed to impede water flow. Surface water fully charged the vertical fracture system to over 250 psi. Water flow created surface sink holes.
RESPEC geologists evaluated the fracture system and chose the most favorable level to cross the fracture zone with polyurethane grouting.
RESPEC mining engineers with a long history of water control devised a polyurethane grouting plan. Probe holes were drilled 30 feet in advance of the face. A unique single component, that foams and sets quickly, was chosen to fill the fractures exposed by probe drilling. Grout is pumped through a packer system designed to withstand 2,000 psi injection pressure. Once all water flow is stopped, a 15-foot advance is shot and material is removed to an underground waste storage area. The procedure is repeated in entries A and B. Entry B development is maintained 50 feet behind entry A to avoid communication through fractures. The project is half finished with proof of concept confirmed.