Reclamation of an in Situ Coal Gasification Test Site in Wyoming

Abstract

In the late 1980s, two coal gasification concepts were tested at a 15acre site in the Hanna Basin of south-central Wyoming. Both tests were conducted in the Hanna No. 1 Coal Seam, which is about 30 feet thick and 365 feet below surface at this site. Approximately 4500 tons and 11,300 tons of coal were burned in the two tests, respectively. The Land Quality Division (LQD) of the Wyoming Department of Environmental Quality (WDEQ) issued Research and Development License No. 15 (RD15) to Stearns Catalytic Corporation (now Washington Group International, Inc.) for the tests. Per the license requirements, ground water restoration and surface reclamation were necessary after the tests. Because of the efficiency of the burns and the effectiveness of venting and flushing the burn cavities after each test, ground water restoration was completed in 1989. Once ground water restoration was deemed complete, the 30+ wells were abandoned and surface reclamation began. The reported seed mix included Wheatgrass (western, thickspike, and slender), Indian Ricegrass, Fourwing Saltbush, and Big Sagebrush. In addition, Big Sagebrush seedlings were also planted. Surface reclamation was completed in 1993, with limited repair work (primarily weed control) in subsequent years. The LQD released the reclamation bond and terminated the license in late 2005. Even though this site was tiny in comparison with most in situ noncoal mines and traditional coal mines, it provides a microcosm of reclamation issues, including: drought impacts; selection of areas for evaluation of reclaimed vegetation; and comparison of species planted with species expressed. It also provides information specific to reclamation issues at in situ mining projects, such as extent of ground water contamination, measurement of revegetation success at sites with multiple, relatively small areas of disturbance, and soil sampling for water treatment impacts. The site was one of the first evaluated for bond release under Category 5 of the LQD Coal Rules.