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CONSTRUCTION MATERIALS: SUBSIDENCE ISSUES IN MINING
Whitney Faulkner, Manager, Environmental Reclamation
whitney.faulkner@respec.com
Beneath the Surface: Mitigating Subsidence in West Virginia
Imagine the ground beneath your feet suddenly giving way, the roof above you buckling like crumpled paper, and the pillars around you surrendering as the earth gives way. Growing up, we may have odd fears about the dangers of quicksand, but what lurks beneath us packs an even heftier punch—subsidence. It isn’t picky where it strikes, and if there’s an underground mine nearby, you can be sure subsidence may come crashing through—or, rather, down. Fortunately, RESPEC has been mitigating these hazards for more than 30 years. As part of the Bipartisan Infrastructure Law, we are working on two projects in West Virginia with subsidence issues.
The Beckley Soccer Complex
In Beckley, WV, the Beckley Soccer Complex is filled with constant movement. You can find trails intertwining, soccer balls soaring—and a parking lot plagued with subsidence and sinkholes. RESPEC is analyzing the subsidence causes and develop mitigation designs. The site’s topography suggests that the scarp line appeared along the crest of the spoil fill. Five boring holes have been proposed in the parking lot and along the scarp line as part of the process. However, the drilling program results indicated that two boring holes did not reach the bedrock for about 61 to 76 feet.
Initially, the plan was to remove all the soft ground down to the bedrock to create a stable foundation. But, because a power company installed power poles along the scarp line, the plan has been revised. Instead, a geogrid will provide additional support, acting as a bridge across the soft material and allowing the team to avoid the power pole location. This approach will limit the excavation required, resulting in cost savings. The team is also looking for on-site spoil disposal areas to further cut down on construction costs.
The project’s next phase will involve finalizing the design, developing construction drawings and technical specifications, and providing engineering estimates.
The MacArthur Subsidence Phase III
Farther south, near MacArthur, WV, a 170-acre area has been marred with subsidence from an old underground mine, potentially affecting 150 nearby landowners. RESPEC designed an exploratory drilling program to better understand the subsidence issues and risks within the project boundary. The program proposes 21 drillholes that are expected to encounter a coal block, mine void, or a rubblization zone. This information will help develop a suitable grouting plan.
Once drilling is completed, RESPEC will evaluate all nearby structures at risk for subsidence. After all structures with foundations have been identified within the risk area, we will begin obtaining construction right-of-entry from property owners within the risk area. The goal of this project will be to mitigate the subsidence risk for the property owners.
The challenges of these two projects highlight the complexities of managing subsidence. RESPEC works to pave the way for stable ground and secure environments. By tackling these issues head on, we’re working toward a safer, more resilient future for both communities.
QUESTIONS?
Contact RESPEC for more information. Whitney Faulkner, whitney.faulkner@respec.com