Laserfiche WebLink
<br />~ iii iiiiiiiiiimiii <br />STATE O~OLORAVv <br />DIVISION OF WATER RESOURCES <br />WATER DIV {S{ON FOUR <br />Office of the State Engineer <br />Department of Natural Resources <br />1540 E. Niagara <br />P.O. Box 456 <br />Montrose. Colorado 81402 <br />Phone (970)249-6622 <br />Fax (970)249-8728 <br />http://water.s[ate.co.us/defau It.htm <br />Joseph J. Dudash <br />Environmental Protection Specialist <br />Division of Minerals and Geology <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver CO 80203 <br /> or eo <br />~ <br />~ <br /> ~ <br />. <br />4, <br />e Q <br />O <br />RECEIVED '• `;'•' <br />ra'!6 <br />DEC 2 7 2000 <br /> Bill Owens <br /> Governor <br />Division of Minerals and Gealagy Greg E. Walther <br /> Executive Director <br /> Bal D. Simpson, P.E. <br /> State Engineer <br />December 21, 2000 <br /> Wayne I. Schieldt <br /> Division Engineer <br />Subject: Comments regazding Bowie No. 2 Mine (permit No. C-1996-083) <br />Dear Mr. Dudash: <br />Thank you for your letter of October 23, 2000 announcing the permit application by Bowie <br />Resources for the expansion of their mine. The purpose of this letter is to provide comments <br />pertaining to the subject coal mining permit relevant to issues surrounding the effect mining activity <br />may pose on the safety of the Bruce Park dam (a.k.a. Terror Creek Reservoir). <br />As described in the application, activity associated with the coal mining process potentially <br />creates two physical ground motions, subsidence or vertical displacement of the existing ground <br />surface, and seismic waves as a result of the ground subsidence. If ground displacements or ground <br />motion of sufficient magnitude occurs in proximity to the Bruce Park dam, integrity of the structure <br />may bejeopazdized. The Bruce Park dan{ is categorized a Class I dam as defined by the Rules & <br />Regulation for Dam Safery. The Class I designation indicates potential for loss of life is probable <br />in the event the dam fails. Bowie Resources claim in their application the "Terror Creek Reservoir <br />is outside the angle of draw of the mine workings." While the revised mine plan shows the <br />theoretical projection of draw on the ground surface does not encompass the Bruce Park dam, the <br />map shows the perimeter is within approximately 4000 feet of the main embankment. Even though <br />experts agree the 4000-foot distance does not pose a serious added risk to the dam, some risk does <br />still exist. Therefore, I concur with Bowie Resources' contention stated in the application that "the <br />embankment could possibly be damaged by mining induced seismicity." <br />The application also indicates, a detailed subsidence study will be completed prior to mining <br />within a mile of the structure, but mentions nothing regarding instrumentation and monitoring of the <br />dam. I feel strongly instrumentation be installed and a monitoring plan be in place before mining <br />progresses inside a 1 mile radius of the reservoir in order to have baseline information available for <br />comparison. The instruments shall measure physical responses ofthe dams and the foundations due <br />to movements or seismic forces that may potentially exceed the available strength of materials <br />comprising the manmade embankments or natural substrata. The monitoring plan must provide a <br />