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~~ti iu~~iiii~iii iii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depslmenl of Nnrtual Resources <br />1711 $hermon 51., Room ? I ~ <br />Denver, Colorodo 80307 <br />Fhane: 15031 8h6-3 Sh: <br />F.\X 130}) R3?-8100 <br />July 12, 1999 <br />Rick Mills <br />Twentymile Coal Company <br />29~ l5 Routt County Road No. 27 <br />Oak Creek. CO 80467 <br />RE: 1998 Annual Hydrology Report Review, Foidel Creek Mine, #C-82-056 <br />Dear Mr. Mills: <br />DIVISION DF <br />rv41NERALS <br />GEOLOGY <br />REC LAMAiION <br />MINING•SAFE TY <br />Bill O.r+n. <br />Grn ernur <br />cre~; E w,l~n~r <br />E ~ecunvc Dncaor <br />h,rcnaei B. Long <br />Division Dveaar <br />The Division of Minerals and Geology (DMG) has completed review of the 1998 Annual <br />Hydrology Report (AHR) for the Foidel Creek mine, operated by Twentymile Coal Company <br />(TCC), permit no. C-82-056. The report was reviewed in conjunction with review of technical <br />revision #32 (TR-32) and focused specifically on comparison of observed impacts versus those <br />prDjected in the proposed Probable Hydrologic Consequences (PHC) section of the permit. <br />General Comments <br />^ The AVM sites require elevations to be annotated on the map with the site name. <br />^ Bedrock well 95M001 should be spotted on the map with its corresponding elevation. <br />^ FO-1 and FO-4 on Foidel Creek are approximately 300 feet apart yet indicate dramatically <br />different values for total dissolved solids (TDS). What explains this large water quality <br />difference over such a short reach of the a]luvium? <br />Monitorint= Frequency <br />Monitoring frequency and water quality sampling was accomplished in almost all cases in <br />accordance with the approved plan for surface and ground water sites. The exceptions noted are <br />as follows: <br />^ No data was provided for Middle Creek alluvial well AVM-2. Please submit data, figures, <br />and a new AHR table of contents for incorporation into the AHR. <br />Sampling compliance for point source discharge points was not confirmed as a part of this <br />review, as the self-monitoring program is administered by the Colorado Department of Public <br />Health and Environment under the Colorado Discharge Permit System. However, data from the <br />pond outfalls was reviewed and determined to be generally consistent with DIv1G field sampline <br />and past discharges. <br />