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STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Oepanment of Natural Resources <br />1313 Sherman St.. Room 275 <br />Oenver. CO 80203 <br />303 8663567 <br />Fax: 303 632-8706 <br />DATE: August 3, 1992 <br />T0: Harry Ranney <br />FROM: Cathy 8egej ~~~-~r` <br />~l Fanw. <br />Gorertv <br />Michael 9. tang, <br />()IVISiOn ~Ira(10r <br />RE: Completion Evaluation, Coal Gulch Mine Permit Application, C-92-079 <br />I have revie~red the geochemistry and water quality information provided by <br />Pennsylvania West Mlntng Company in the permit application <br />submitted July 20, 1992. The data provided fs inadequate for baseline <br />information and I recommend that the application be called incomplete. <br />~Geochemicai baseline information is provided in the form of three samples <br />acquired from the open highwall at points immediately above and below the coal <br />seam. This information showed two samples with acidic pHs (4.9 and 5.3) and <br />the floor sample with a pyritic sulfur concentration of 3.26X. The acid base <br />potential and neutralization potential were not noted. The operator needs to <br />drill at least three holes and sample on four foot intervals throughout the <br />column per ruse 2.04.6(3)(d)(tii)(C> and (D) and as outlined by the Division's <br />Guidelines of Baseline Water Quality and Overburden Geochemistry Data. This <br />is a shallow mine, with overburden thicknesses ranging from 75' at the portal <br />to 500'. Subsidence will result in increased vertical permeability throughout <br />the column that will cr?ate new pathways for water migration into the mine. <br />Given the acidic nature of the floor material, it i; prudent to ascertain the <br />geochemical nature of the stratigraphic column to the Point !eokout Sandstone, <br />below the coal Seam. <br />lest holes should be used to characterize the physical proper*,tes of the <br />overburden per Rule 2.04.6(3)(a)(iii)(A) and 2.04.7(1)(b). Information on <br />transmissivity, storativity~permeability and porosity should by acquired. <br />Drawdown tests should he performed following consultation with the Division. <br />~/ertical permeability will probably provide the best pathways for water to <br />migrate into the mine. Therefore, I would recommend that holes be placed in <br />Coal Gulch, Cherry Gulch and the northern tributary of Cherry Gulch to obtain <br />a worst case evaluation of permeability. Recharge, discharge and storage <br />characteristics of the permit and adjacent areas must be described. <br />Baseline water quell <br />and 2.04.7(2)( <br />Gulch alluvium <br />dying <br />reriec <br />e analyzed semi <br />OF^~(O <br />~e~~~ <br />• ~ atr„~. <br /><b>>. Pennsylvania <br />d downstream from t <br />the coal seam. and <br />ri <br />regime crcuies <br />st must establi <br />mine,. n he Pc <br />alluvial aquif <br />sonai <br />7( )(a (iii) <br />lls in the Coal <br />es <br />fifer and <br />locations. Field .water qua <br />u1T suiEe'che 7m cal analyses <br />