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iii iiiiiiiiiiiii iii sss . DIVISION OF MINERALS AND GEOLOGY DepanmeN of Natural Resources 9 313 Sherman 51., Room Z15 Denver, Colorado 80?03 Phone: (3031 866 3567 FAk: p03) ffi2-81 Uh Memorandum DATE: September 18, 1998 TO: Janet Binns ~ FROM: Kent Gorham V (~ RE: 1997 Annual Hydrology Report, Foidel Creek Mine, #C-82-056 CC: Dan Hernandez I have completed review of the 1997 Annual Hydrology Report for the Foidel Creek Mine. Overall, the operator did an outstanding job of completing the hydrologic monitoring requirements as per the approved plan. The report was also well organized, cleaz, and concise. Graphs, tables and maps were well done and accurate. A report of this quality should be the standazd for all Colorado coal mines. ~~~~~ DEPARTMENT OF NATURAL RESOURCES Roy Rumor Gnvemor lames 5. Lnchheazl Eeecmice Director Michael B. Long Division Dneclor The mine is affecting ground water levels in the Wadge overburden due to undermining and subsidence. Water levels in FBR- l 1 a have declined over 150 feet in the last three yeazs. Water levels in well 006-82-74C appear to be recovering slightly, likely due to the completion of mining in the immediate vicinity. Water quality also indicates evidence of the movement of natural groundwater to the well bore, as TDS levels have gone from 3300 mgll to near 1000 mg/1. We1191 M006 also shows a decline of nearly 150 feet since 1992, with a quality that is fairly well represented by 900 mg/I TDS. Well 93M001 shows a steady decline since April of 1996, likely due to mining and subsidence downgradient. No impacts beyond that predicted in the PHC are evident. STATE OF COLORADO Alluvial well data show seasonal, yet stable water levels and quality remains primarily dictated by the quality of the adjacent stream. Foidel Creek alluvial water quality downstream of the mine facility shows a steady increase in EC, from 1400 umhos/cm in