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l III IIIIIIIIII'lllll • <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman 51., Room 215 <br />Denver, CO 80203 <br />Phone: 1303)866-3567 <br />FA%:1303) 832-8106 <br />December 28, 1992 <br />• <br />STATE OF COLORADO <br />ti~ ~, ~1p9 <br />•~ <br />r8]6 ~ <br />Roy Ramer <br />Governor <br />Michael B. Long <br />Division Director <br />TO: Susan Morrison] ~ <br />FM: Shawn Smith_- <br />Re: Annual Ground Water Hydrology Review for Senaca II (C-80-005) <br />Dear Susan: <br />I have reviewed the 1991 (submitted February 1992) Annual Hydrology <br />Report from Senaca II. In addition, 2 have also reviewed the <br />following documents: <br />Findings Reports: 11/31/86 and 11/12/92 <br />Midterm Review: 01/17/90 <br />Permit: Sections on Ground Water, PHC and Geology (Tabs 5 & ~ <br />Technical Revisions <br />Minor Revisions <br />Stipulations <br />Jeff Martin memos: dated 7/15/92 and 08/05/92 <br />PARAMETER CHECK <br />All ground water wells in the permitted area were reviewed for <br />stock/irrigation recommended standards except for one case; well <br />///~~~ GW-S5-TC which was analyzed for domestic use standards. <br />Electrical conductivity values (conductivity values associated with <br />,\ , salt content) were high in all wells. However, the relationship <br />\'(1~ between EC and TDS was within limits, TDS never exceeding the 5000 <br />mg/1 standard for irrigation purposes. It is necessary to mention <br />that according to Jeff Martin's memo dated July 15, 1992, ground <br />water is not being p~ ed for "either irrigation or stock <br />watering." Only one we1~;JGW-SS-TC is used for any beneficial use, <br />primarily domestic use ~~ the mine site. In general, most wells <br />showed an increase in TDS, but all still remained within the 5,49.0. <br />mg/1 limi Three wells in particular should be watched for <br />urther 3-ncreases over time in TDS levels: GW-S6-A, GW-531-A2, both <br />in Little Grassy Creek Alluvium and well GW-S68-A in an unnamed <br />tributary to Fish Creek. These three wells show a steady increase <br />in TDS and are part of alluvial valley floor system for Fish Creek <br />and eventually the Yampa River system. An additional well, GW-517- <br />W in the Wadge Coal seam, also appears to show a steady increase of <br />TDS and should be carefully monitored in 1993. Curiously, all the <br />spoil wells showed a decrease in TDS from 100 to 200 m 1 from 1990 <br />to 1991. This may be due in part to low preci itation levels <br />I 77 <br />~ s -~'~-~T q,lo~. , <br />