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:. <br /> <br />r~ <br />L <br />COLORADO YAMPA <br />COAL COMPANY <br />A Cyprus Amax Company <br />June 2, 1998 <br />Janet Binns <br />~olorado Yampa Coal Company ~ <br />29515 Routt County Road #27 G' <br />Oak Creek, Colorado 80467 ~ \y` <br />(970)879-3800 <br />RECEIVED <br />JUN ~ 4 1998 <br />Environmental Protection Specialist <br />Division of Minerals and Geology Division of Minerals8t~eob~ <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />RE: Mine No. 3, C-84-062, Response To The Annual Hydrology Report Review <br />Dear Ms. Binns: <br />The following comments are submitted in response to the concerns noted during the <br />division's review of Colorado Yampa Coal Company's 1997 Annual Hydrology Report: <br />Spoil spring monitoring was not completed during the month of May 1997 in <br />accordance with the monitoring plan. I would note however that May was a very <br />wet month, making both access and identification of several of the springs <br />difficult. <br />I have enclosed, herein, a copy of the 1997 U. S.G.S Precipitation Record for Site <br />900. Based upon this record and your own observation of both weather and <br />hydrologic conditions as stated in your May 29, 1997 Inspection Report, I am <br />confident that the June spoil spring monitoring provided valid flow measurements <br />for the determination of additional sampling. <br />1998 spoil spring monitoring was completed during the month of May 1998. <br />The division's assumption that the total combined flow from site 700 and site 900 <br />should approximate the flow at site 29 is valid. However, the differing formats in <br />which the flows are recorded makes that comparison difficult. The flow values <br />recorded by U.S.G.S. for site 700 and site 900 reflect a `daily mean' of the values <br />collected by a water-stage recorder. The values recorded for site 29 reflect an <br />`instantaneous' rated flow based upon a curve generated by periodic stream <br />gaging. <br />A precipitation event on the day of a comparison would further confuse the issue. <br />Even the delayed runoff from an event on the day prior to a comparison would be <br />confusing. <br />