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~ ~ • III III III III IIII III ~~~°~ F STRTE OF~OLORf~DU u Roy Romer, Governor ~~~ . ~ c-' DEPARTMENT OF NATURAL RESOURCES MINED LAND RECLAMATION DIVISION FRED R. BANTA, Dlnetor DATE: May 26. 1988 T0: Dennis Burns, Albuquerque Field Dffice FROM: David Holm, Inactive Mine Reclamation Supervisor RE: Reclamation of the Thompson No. 2 Coal Mine at the Snowmass Coal Mine site As you know the Inactive Mine Reclamation Program designed and constructed a passive mine drainage treatment system at the abandoned Thompson No. 2 Coal Mine located near Carbondale, Colorado. The Thompson No. 2 PMDT system was constructed early in 1985. Prior to any work at the site, the Inactive Mine Program received approval from the Colorado Water Quality Control Division (WQCD) to construct the Thompson PMDT system as amine drainage abatement feasibilty study. Potential requirements for a IJPDES permit were waived by • the WQCD. Also, negotiations between Colorado's Title V and Title IV reclamation programs and officials at the Snowmass Mining Co. occurred in which it was decided that the AML project area should be removed from the permitted area of the Snowmass Mine. Accordingly, the Inactive (Nine Reclamation Program assumed reclamation responsibility for the disturbances created by the passive mine drainage treatment project. The passive mine drainage system incorporates three basic facilities. A constructed iretland receives drainage from the abandoned Thompson No. 2 Mine portal. The purpose of the constructed wetland is to remove heavy metals by adsorption into the organic substrate of the constructed wetland and by plant uptake. The mine drainage filters through this constructed wetl~snd and discharges into a 4 inch diameter ABS plastic pipe which conveys the drainage down a steep hill slope into a limestone filled channel. A series of drop structures were created in the limestone filled channel in order to provide aeration and to exsolve carbon dioxide from the mine drainage. 'this channel conveys the drainage to Thompson Creek. The- PMDT system constructed at the Thompson No. 2 Coal Mine has Keen extremely valuable in elucidating the design and construction principles which are useful in passive mine drainage system applications. This system was beset by marry environmental and technical problems. Construction was aca~mplished during harsh winter conditions. After completion this system experienced minus 30°F operating temperatures and freezing of water in conve;iance pipes was a problem. Unprecedented variations in flows discharged from the mine . portal occurred during the first year of operation. During the 20 years of observed flows from the mine preceeding construction of the trea trnent system 215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567