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<br /> <br />STATE OF COLORADO <br />Roy Romer, Gove~ <br />DEPARTMENT OF NATURAL RESOURCES <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTON, Director <br />DATE: July 20, 1987 <br />T0: Michael Savage <br />FROM: John T. Doerfer <br />RE: ALTERNATE SEDIMENT CONTROL - BOURG STRIP MINE - FILE N0. C-81-021 <br />I have reviewed the material received from the State of Wyoming concerning <br />alternate sediment control (ASC), The information sent included selected <br />sections from the Antelope Mine permit application and a memo from OSM <br />clarifying the federal position on the definition of "siltation structures" <br />following the Flannery decision. I am providing the following comments for <br />your use in considering the possible Bourg ASC experimental practice proposal. <br />1. The environmental conditions in Central Wyoming where the Antelope Mine <br />is situated may compare more closely to conditions near Grand Junction <br />than those in North Park. Data on soils and the precipitation regime <br />should be compared if Walden Coal Company wishes to make an analogy of <br />conditions similar to Wyoming as part of their justification for <br />proposing alternate sediment rontrol, <br />2. The Antelope proposal defines four (4) advantages to ASC (page 143). As <br />these are used to justify the use of ASC, each should be evaluated as to <br />their merits as discussed below: <br />1, The avoidance of channel degradation downstream of ponds due to clear <br />water discharge may be overstated. Few ponds are actually as <br />effective in removing suspended sediment as the designs might <br />presuppose. <br />2. The limitation on land disturbance due to construction of ponds is a <br />valid statement, however this applies more to regrading ponds at <br />final reclamation stage than during the developmental phase. <br />3. The statement of less disruption to the hydrologic balance by <br />avoiding pond storage, seepage and evaporation losses fails to <br />acknowledge the increase in runoff from disturbed areas during <br />mining. This argument may "hold water" during the final vegetation <br />establishment phase of reclamation, however. <br />4, The avoidance of the high cost of pond construction is a valid <br />advantage, however the high cost of monitoring and maintaining <br />alternate controls, especially if failure and replacement occurs, <br />counterbalances this argument to some extent. <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />