Laserfiche WebLink
f ( ,. <br />Subsidence 14onitorinn <br />While ARCO plans to prevent any subsidence effects under the Dry Fork, <br />Horse Creek and South Prong stream channels, detailed subsidence <br />information will be gathered over the life of the mine. This will <br />allow the mine plan 'and design to be adjusted as new information on <br />subsidence effects is obtained. The mine plan calls for mining to <br />proceed throughout the lease block in a counter-clockwise manner. <br />Approximately ten years will elapse before the mains, "limited <br />mining", extend beneath the Dry Fork and approximately 11 years before <br />active mining takes place around the western course of Dry Fork. It <br />will be another 29 plus years before mining is projected to occur <br />under the eastern half of Dry Fork. Therefore, ample time will be <br />available to gather subsidence data prior to mining in the vicinity of <br />Dry Fork. <br />The subsidence program will consist of establishing a network of sur- <br />vey monuments to monitor any vertical and horizontal displacements. <br />The first net~.vork will be installed over the first panel to be fully <br />. mined, with other net~.vorks established at appropriate locations as <br />mining progresses. Data from these net:vorks will be used to verify <br />the design of the buffer zone under the Dry Fork and predict the <br />magnitude of subsidence effects expected over the rest of the pro- <br />perty. <br />As an additional precaution, a subsidence monitoring nettivork is <br />planned for the Dry Fork area to assure that no adverse impacts affect <br />the stream channel as mining approaches the area. <br />• <br />(13) <br />