A New Face on Reclamation
By Andy McAllister, Watershed Coordinator
The traditional approach to Abandoned Mine Land (AML) reclamation has provided minimal diversity for plants and wildlife and is not visually satisfying. With the traditional method, the mine sites are reclaimed to a point where they have uniform, smooth, grassy slopes. The smooth slope is compacted to prevent erosion. The traditionally reclaimed area often appears very different compared to the surrounding landscape. I”m sure we all can think of numerous sites where this is occurring. The concept of Geomorphic Reclamation however, offers us a different way of looking at reclamation.
In terms of mining reclamation, Geomorphic Reclamation is landscape reconstruction that attempts to come close to the original surface forms surrounding the mined area, thereby mimicking the natural drainage patterns of a natural landscape. The final goal of this procedure is to have a finished site that is in a stable hydrologic equilibrium (minimizing soil erosion) while at the same time being visually appealing.
The technique was originally developed at active mining sites in New Mexico in 2006, and is now gaining acceptance throughout the country for use in active as well as abandoned sites. The computer software developed to incorporate geomorphic landform designs is called “Natural Regrade” and is available from Carlson Software in Colorado. The U.S. Department of the Interior’s Office of Surface Mining, Reclamation and Enforcement (OSM) has named Carlson Software’s Natural Regrade a “Core Software” for its Technical Innovation and Professional Services (TIPS) task force for use in mine reclamation design and review.
The practice of reclamation using geomorphic principles was put to the test during the summer of 2006 at the La Plata Mine in New Mexico. The mine received over two inches of rainfall within a two-hour period. This is equivalent to a storm in that area with an approximate recurrence interval of 200 years. Much of the reclamation was new and had just been topsoiled that year, but because of these innovative reclamation techniques used, there was astonishingly little erosion.
Techniques used at the mine that helped minimize erosion include a combination of highly scalloped slopes which create drainage density, sinuous drainages which reduce gradient and concave slope shapes which slow the water velocity near the bottom of slopes. All these practices mimic the shapes that nature creates in hill slopes that are lacking bedrock control. In the end, the runoff from the unvegetated reclamation site was such that it didn’t create the erosion one might expect.
Old highwall site reclaimed using Geomorphic Reclamation principles. Log Creek Church, Indiana. Scalloped slopes in the upper right direct runoff from those areas into the “squiggly ditch” in the center of the photo.
Photo courtesy of Indiana Geologic Survey.
So far, Geomorphic Reclamation has proven to require less maintenance than traditional reclamation and creates a more diverse and natural looking wildlife habitat. But this practice isn’t just confined to states in the far west. The State of Indiana has begun to use Geomorphic Reclamation on abandoned mine reclamation projects in their state.
The Log Creek Church highwall reclamation project in the southern part of the state is an example of how a geomorphic approach leads to a more natural looking reclamation project which eliminates the use of terraces and rock-lined ditches. Scalloped slopes were constructed in this former highwall site and small, concentrated drainage areas were created. The main drainage channel affectionately called “the squiggly ditch” served to dissipate the runoff’s erosive energy without using boulders or other methods of deflection. The resulting drainage pattern was more stable, even before it was revegetated, and in the end will provide better habitat for aquatic flora and fauna.
For more information on Geomorphic Reclamation: