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~ III IIIIIIIIIIIIIIII STAT~OF CULUKAllU MINED LAND RECLAMATION DIVISION Department of Natural Resources 1313 Sherman St., Room 215 Denver. GO 80203 303 e66-3567 Fax 303 832 6106 DATE: August 3, 1992 T0: Harry Ranney FROM: Cathy Begej 1J~ ~-~p r OF'CO~ i`~~90 NQ~ (~~~ O • ' 4® f i ~ re76 ~ Roy Romer, Governor Michael B. Long, Division Director RE: Completion Evaluation, Coal Gulch Mine Permit Application, C-92-079 I have reviewed the geochemistry and water quality information provided by Pennsylvania West Mining Company in the permit application submitted July 20, 1992. The data provided is inadequate for baseline information and I recommend that the application be called incomplete. Geochemical baseline information is provided in the form of three samples acquired from the open highwall at points immediately above and below the coal seam. This information showed two samples with acidic pHs (4.9 and 5.3) and the floor sample with a pyritic sulfur concentration of 3.26%. The acid base potential and neutralization potential were not noted. The operator needs to drill at least three holes and sample on four foot intervals throughout the column per rule 2.04.6(3)(d)(iii)(C) and (D) and as outlined by the Division's Guidelines of Baseline Water Quality and Overburden Geochemistry Data. This is a shallow mine, with overburden thicknesses ranging from 75' at the portal to 500'. Subsidence will result in increased vertical permeability throughout the column that will create new pathways for water migration into the mine. Given the acidic nature of the floor material, it is prudent to ascertain the geochemical nature of the stratigraphic column to the Point lookout Sandstone, below the coal seam. Test holes should be used to characterize the physical properties of the overburden per Rule 2.04.6(3)(a)(iii)(A) and 2.04.7(1)(b). Information on transmissivity, storativity~permeability and porosity should by acquired. Drawdown tests should be performed following consultation with the Division. Vertical permeability will probably provide the best pathways for water to migrate into the mine. Therefore, I would recommend that holes be placed in Coal Gulch, Cherry Gulch and the northern tributary of Cherry Gulch to obtain a worst case evaluation of permeability. Recharge, discharge and storage characteristics of the permit and adjacent areas must be described. Baseline water quality evaluations need to characterize the seasonal variability in the ground and surface water regime (Rules 2.04.7(1)(a)(iii) and 2.04.7(2)(a) and (b)). Pennsylvania West must establish wells in the Coal Gulch alluvium, up and downstream from the mine, in the Point Lookout Sandstone underlying the coal seam, and the alluvial aquifer should be monitored for field parameters monthly and full suite analyses quarterly. There should be at least three wells constructed for each bedrock aquifer and they should reflect both updip and downdip locations. Field water quality parameters should be measured monthly and full suite chemical analyses should be analyzed semi-annually.