Laserfiche WebLink
<br />Jim Nerron <br />-3- <br /> <br />June 4, 1982 <br />Conceptually, the company will first have to define the boundaries of the <br />alluvial bodies to be protected adjoining the Cottonwood and Rapid Creek <br />channels. Secondly, projection of those boundaries to the level of the coal <br />seam along the assumed 25° angle-of-draw will need to be completed. Thirdly, <br />the appropriate pillar configuration will have to be developed to assure <br />stability of the areas requiring protection. Fourthly, a test panel to be <br />mined early in the mine life will have to be monitored in order to confirm the <br />performance of the designed pillar configurations, including appropriate <br />hydrologic monitoring of any alluvial aquifers associated. <br />Subsidence Monuments <br />Subsequent responses by Powderhorn Coal Company have indicated that subsidence <br />monuments have already been installed within the Cottonwood lease tract <br />paralleling the Ute Water District raw collection pipelines. These monuments <br />are reported to consist of 7/8" diameter rebar driven approximately 18 inches <br />into the ground on approximately 300' spacings. I do not believe that these <br />monuments will resist normal traffic, wildlife or meteorological forces and <br />should be replaced by more substantial monuments. In addition, specific test <br />panels, if required to verify the subsidence control plan beneath the potentially <br />affected creeks, will require significantly more substantial and reliable <br />"caisson-type" monument installations. <br />/mt <br />cc: Dave Shelton <br />Fred Banta <br />