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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanmem of Nawral Resources .~ <br />1313 Sherman 51.. Room 215 <br />Denver, Colorado Bo?03 <br />DIVISION OF <br />Phone: Uo31 s66-3567 MINERAL 5 <br />FAl(: (303) 832-8106 $i <br /> GEOLOGY <br />June 9,240 FECLAMA71ON <br /> MINING•SAFETY <br />Mr. Mike Altavilla all ovens <br />Seneca Coal Company cOPef"°r <br />Box 670 Greg E. Walther <br /> Executive Dhcaor <br />Hayden, CO 81639 Michael 8. Long <br /> Division Director <br />RE: Seneca II-W, Permit No. C-82-057 <br />1999 Annual Hydrology Report <br />Dear Mr. Altavilla: <br />The DMG has reviewed Seneca Coa] Company's 1999 annual Hydrology Report for the <br />Seneca II-W Mine. The report is well written and the data are presented in a concise <br />manner. However, several deviations from the approved monitoring plan were noted for <br />the frequency of data collection. <br />SCC adequately addressed the Division's comments on [he 1998 AHR by incorporating <br />responses into the 1999 AHR. The Division has the following comments concerning the <br />1999 AHR. These comments could be inserted directly into a review letter to the <br />operator. <br />1. With approval of PR-02, SCC committed to conducting semiannual (June and <br />September) monitoring at site SW-S2W-SG9, SW-S2W-SG16, and SW-S2W-SG17. On <br />page 12 of the AHR, SCC states that these sites are not part of the required monitoring <br />program. Please ensure that sampling resumes at these sites according to the approved <br />hydrologic monitoring program for the 2000 calendar year. <br />2. Water level information was not provided for August at GW-S2W-4W and GW- <br />SZW-4WC groundwater monitoring locations. Water level data was not obtained in <br />August and October/Novembercnd water quality data was not provided for <br />OctobedNovember for well location GW-S2W-40V 1. Triannual water level monitoring <br />was not provided for well location GW-S2W-40V2. <br />3. Semiannual water quality data were not provided for spring 5-47. Discharge <br />information and water quality data were not provided for spring S-49. <br />4. On page 15 of the 1999 AHR, SCC indicates that TDS values from Site SW- <br />S2W-FG4 would be more appropriate for determining Sage Creek premining load <br />determination for TDS. The current PHC calculation for determining impacts to Sage <br />