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iii iiiiiiiuiiu iii <br />999 <br />• <br /> <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depannsnt o(Namral Resources <br />131 }Sherman 51.. Room 215 <br />Denv?r, Colorado aW0} D I v 15 1 0 N O F <br />Fhone an}lai,ra-}se; MINERAL S <br />FAX. p03) a3?-a106 6c <br /> GEOLOGY <br /> R E C L A M A T I O N <br /> MINING•SAFETY <br />August l3, 1999 ' <br /> B~II Owens <br /> Governor <br />Michael G. Altavilla <br /> Grey, E watcher <br />Seneca Coal Company Esecutwe Dueclnr <br />P.O. Box 670 <br />Michael B LonS <br /> Division Dneclo~ <br />Hayden, CO 81639 <br />Re: Yoast Mine (Permit No. C-94-082) <br />1998 Annual Hydrology Report Review <br />Dear Mr. Altavilla: <br />The Division has reviewed Seneca Coal Company's (BCC's) 1998 Annual Hydrology Report <br />(AHR) for the Yoast Mine. The frequency of data collection is incompliance with the approved <br />monitoring plan contained in the permit document. SCC did a good job at collecting and <br />reporting the required monitoring data. The report is well written and the data are presented in <br />a concise manner. <br />The Division had several comments on the 1997 AHR in our review letter dated October l5. <br />1998. SCC addressed these comments and incorporated the Division's recommendations into the <br />1998 AHR. The Division has the following comments concerning the 1998 AHR. <br />1. SCC has compiled a list of ground water standards for agricultural uses (Table 5) and a <br />list of surface water standards for agricultural uses (Table 9). As suggested by the Division, <br />these lists have been composed mostly of Colorado Department of Public Health and <br />Environment (CDPHE) ground water standards as of April 1996 and CDPHE surface water <br />standards as of August 1997, respectively. Please note that [he standards have been recently <br />updated. The last effective update for both the ground water standards and surface water <br />standards was March, 1999. <br />2. The Division notes that the AHR record indicates apparent exceedances of the CDPHE <br />Basic Standards for Ground Water. As reported in the 1998 AHR and previous AHRs, isolated <br />exceedances of ground water standards have occurred for certain metal constituents, TDB, and <br />sulfate. TDS increases in groundwater resulting from spoil discharge are discussed in detail in <br />the Probable Hydrologic Consequences discussion in the permit document (PHC). h} addition, <br />trend analysis is provided for TDS a[ each ground water well location in the AHR. Has SCC <br />identified the potential source for the apparent elevated levels of certain metals and for sulfate <br />presented in Table 6 of [he 1998 AHR? Are concentrations for these metals and sulfate <br />