LAND RECLAMATION

Under natural conditions, a landscape represents a balance of geomorphic processes; this dynamic stability is disrupted by mining. In this context, the goal of reclamation is the reestablishment of the steady state. In the United States, regulations tightly control the reclamation process at active operations, dictating the slope (AOC), the extent of revegetation, and the rate at which reclamation and revegetation must proceed. Failure to comply results in loss of bond money and/or fines. Other countries (e. g., Canada) have more flexibility built into their regulatory structure. They consider the imposition of AOC inappropriate at many sites—for example, in areas where flat land would be desirable; enhanced flexibility allows such aspects to be negotiated. In the United States, exceptions can be granted by the OSM, but are atypical. Instead, operators have learned to operate within the limits of the regulation. For example, they may choose to reduce erosion potential on steep slopes by installing terraces and manipulating infiltration rates.

When reclamation agencies are attempting to reclaim derelict or abandoned operations, no attempt is typically made to restore the land to AOC. Instead, the primary intent is to remove potential hazards (e. g., extinguish potentially dangerous mine fires, seal mine openings); secondarily, the intent is to bury acid­forming material, and, finally, to create a stable surface that will resist erosion with minimal maintenance. Funds for reclamation of abandoned sites are quite limited and represent a small fraction of what would be necessary to reclaim all abandoned mine sites.

Many abandoned sites have developed a natural, if sometimes sparse, vegetative cover of volunteer species. In addition, an unusual incentive has recently developed that may encourage companies to reclaim abandoned sites that have not naturally revegetated. As pressure gradually grows on companies to lower carbon emissions, proposals have been made that credit should be given for revegetating barren lands, because this would sequester carbon from the atmo­sphere. Arid deserts and barren abandoned mine sites are the two most likely types of places for such an effort, if and when it becomes codified.

Another aspect of mined land remediation is subsidence control. Because subsidence events above old room-and-pillar operations commonly cluster, when subsidence begins in an area, state and OSM emergency personnel are quickly mobilized. Typi­cally, they attempt to backfill, inject, or stow, hydraulically or pneumatically, as much solid mate­rial into the mine void as possible, figuring that reducing the void volume with fine solids (sand, fly ash, etc.) will both decrease the amount of sub­sidence that will occur and reinforce pillars that might otherwise fail. However, because the mine voids that they are injecting the material into are often flooded, it is sometimes difficult to ascertain if these efforts make much of a difference. An alter­native option pursued by many landowners in undermined areas is government-subsidized subsi­dence insurance. This insurance fund pays property damage after subsidence has occurred.

Updated: December 19, 2015 — 8:50 pm