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© MONTGOMERY WATSON <br />Mining Graup <br />July 23, 1999 <br />Rick Mills <br />Twentymile Coal Company <br />29515 Routt County Road #27 <br />Oak Creek, CO. 80467 <br />Dear Rick: <br />III IIIIIIIIIIIII III <br />999 <br />[ have enclosed seven (7) revered SEDCAD4 runs which model Pond D for the 100 Year storm event. The <br />DMG requested that we analyze Pond D for the 100 year event since it is a MSHA pond. As sorted in my <br />phone messaee [o you. we should have realized Ihm the pond needed to be analyzed for the 100 year event. <br />Therefore, there will be no charee for this service. The 100 fear. 24 Hour storm was analyzed rather than <br />the 6 Hour storm since it produced a hieher peak fluty. The DMG stated you could simply submit the new <br />anah's'is. <br />I have sent you the runs that utilize bo[h the principal and emereency spillways to pass the peak flow. <br />However, if the Department wants the pond analyzed with the principal spillway cloeged (nut required by <br />regulation). I have thnt analysis complete and i[ shows that the emergency spillway is adequme. The DMG <br />~~ stated they will he sendine you a lever with a couple of comments concernine Pond D, however. they <br />indicated that the comments were minor. <br />~ If you have any questions, please contact me. <br />Sincerely. <br />Dom,. ~.-L. <br />Dan Keuscher <br />Montgomery Watson <br />Cc: Tom Leidich <br />File <br />165 Somh Union Blvd. Tel: 703 753 SIdO <br />Suiie 460 Fax: 3037635003 Serving the World's En vironmenral Needs <br />Lakewood,CO <br />80228 ' <br />