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Subsidence <br />CWI proposes to mine the "D" seam, utilizing conventional room-and-pillar <br />methodology. The applicant has completed the required inventory of <br />structures, a sample inventory for cultural resources and renewable resource <br />lands, a projection of probable subsidence, and developed a subsidence control <br />plan and appropriate 2ccompanyiag subsidence monitoring plan. <br />CWI has identified 29 structures within the permit and adjacent areas. . <br />Nineteen of these structures were inventoried within the permit area, as well <br />as two water pipelines and an all-weather gravel road within Steven's Gulch. <br />CWI has identified four archeological sites in areas of less than ]000 feet of <br />overburden, and therefore could be affected by subsidence. Three of these <br />sites have been recommended as not eligible for the National Register of <br />Historic Places and the other one requires further evaluation to determine its <br />eligibility. As a condition of mining plan approval, CWI will be required to <br />provide a contingency plan for protection of this site in the event subsidence <br />could affect the site. CWI has also identified several alluvial/colluvial <br />surficial deposits which constitute renewable resource lands within the <br />revised permit area. <br />Surficial deposits have been identified within Steven's Gulch, East Roatcap <br />Creek, and in the area of the Morrell Cow Camp. The applicant has committed <br />to the completion of additional hydrologic investigations within these <br />surficial deposits during the summer of 1985. As a portion of these <br />investigations, additional shallow alluvial monitoring wells will be installed <br />within these deposits for the purposes of monitoring potential effects of <br />subsidence upon the hydrology of these surficial deposits. <br />Vertical subsidence is projected to reach a maximwo of approximately six <br />• feet. Subsidence monitoring has been conducted within the Orchard Valley <br />permit area, in compliance with the originally approved permit. To date, the <br />results of the monitoring program have been limited. However, the data <br />collected to date corresponds with the technica] projections for anticipated <br />subsidence, CWI has completed strain projections for the structures <br />inventoried. Strain projections have also been completed for the two water <br />pipeline which cross the life-of-mine potential subsidence area. These two <br />pipelines are the Pitkin Mesa pipeline, which supplies potable water to <br />roughly 160 domestic taps, and the Industrial Water Supply pipeline for the <br />Orchard Valley mine. <br />CWI has proposed a subsidence control plan to prevent material damage from <br />occurring to the renewable resource lands within Steven's Gulch and East <br />Roatcap Creek. While neither of these areas will be undermined during the <br />initial S-year permit period, future permit mining activities will undermine <br />both of these areas. The II.S. Bureau of Land Management lease C-37210 bears <br />stipulations addressing these same areas. <br />• <br />