RECLAMATION SUCCESS

The Red River Coal Mining Company was especially recognized for its innovative management of groundwater in the mining of a large flood plain area. The Oxbow Lignite Surface Mine, located near Coushatta, Louisiana, supplies approximately 750,000 tons of lignite per year. The mine is a single-seam, dragline, surface operation.

In order to conduct surface mining in the flood plain area, the ground water flow needed to be cut off and removed. A slurry (mud) wall was constructed to block the flow. This was done by placing a mixture of water and swelling clay in a trench as it was being dug out. The following photograph shows this process.

A cap was built over the trench to keep the soil paste from drying and cracking. This wall cap served to prevent flooding inside the mining block. By utilizing this method of managing the ground water, the company was able to recover the maximum amount of coal from the reserve, while at the same time minimizing any adverse effects to the environment.

A dewatering system was installed to remove the existing ground water in the mining area after the slurry wall was in place. This included the construction and placement of 110 wells, which used 2-HP (horse power) electrical pumps. The water from this system of wells was discharged from pipes, then run along a mile long stretch of grassy ditch to a sedimentation pond, and finally released to Bayou Pierre. Discharges were studied and monitored to make certain they met water quality standards.

Applicable State and Federal fish and wildlife management agencies were consulted to monitor their efficiency in impacts and reclamation. Surveys indicated that cottontail rabbits, armadillos, coyotes, white-tailed deer, raccoons, and other species were present in the area.

After mining activities are completed, the slurry wall will be cut in several places to allow for the re-establishment of ground water flow. The sedimentation pond will be a permanent feature to the reclaimed area. It serves to enhance the appearance of the site and benefit the wildlife.

Part of the permitted area is currently being reclaimed into pastureland and will be strengthened with fish and wildlife features. It has been determined that the quality of the soils in the flood plain area will be enhanced due to the elimination of heavy clays.

This project was unique in several aspects. It was the first time the slurry wall technology was used for such a large flood plain area to manage ground water. Another significant characteristic of this environmentally responsible company was its willingness to share information and technology with any other interested parties.