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iii iiiiiiiiiiiiiiii <br />STATE OF COLG~~~~ <br />Roy Romer, Gove~ <br />DEPARTMENT OF NATURAL RESOURCES <br />MINED LAND RECLAMATION DIVISION <br />FRED R. BANTA, Dlreetor <br />January 23, 1989 <br />M11r. John Walters <br />Chief Engineer <br />Salt Creek Mining Co. <br />751 Horizon Court <br />Grand Junction, Colorado 81506 <br />Re: Drainage Control and Diversion Structures for Coal Waste Piles <br />Dear Mr. Walters: <br />During the 1988 oversight year, the Federal Office of Surface Mining initiated <br />a special study in reviewing Colorado's approved program. The subject of the <br />study was drainage and diversion ditch design for coal waste piles. During <br />this review it became apparent that drainage and diversion structures for some <br />waste piles were designed and constructed to control a 10 year-24 hour storm <br />event. Colorado regulations require that these types of structures be <br />designed and constructed to safely pass a 100 year-24 hour storm event. <br />Specifically, see Colorado Rules 4.10.3(2) and 4.09.2(7). During our original <br />review, the Division interpreted the regulations such that these structures <br />were treated as temporary diversions only required to pass a 10 year event. <br />These structures were constructed in accordance with the approved plan, <br />however, the Division's interpretation was in error. <br />In order to resolve this problem without the use of enforcement actions, the <br />Division has entered into an agreement with OSM. To ensure that all coal <br />waste piles within the state meet the 100 year requirement, the Division has <br />reviewed the designs for all approved waste piles. All designs must be in <br />compliance by April 30, 1989 with actual on the ground modifications completed <br />by flay 30, 1989. Revision of designs by technical revision and on the ground <br />modifications by these dates will avoid the possibility of an enforcement <br />action being taken. <br />Enclosed is a memo which details the specific potential problems related to <br />your mines' refuse disposal area. <br />215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />