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<br />closely spaced, high-resolution subsidence monuments. The visual <br />inspection phase consists of a walk-over of the ground surface above <br />mined areas on a semi-annual frequency. In future permit periods, <br />when renewable resource lands and structures may be undermined, pre- <br />and post-mining inspections of structures will be incorporated. The <br />applicant also commits to daily inspection of the Steven's Gulch road, <br />in order to protect the public. <br />Monitoring stations No. 1 through No. 27 comprise a wide-spaced <br />monument grid on approximately 1300-foot centers east-west and <br />2600-foot centers north-south. These monuments provide general <br />observations regarding the magnitude' of vertical subsidence <br />occurrences. Addittonai wide-spaced monuments No. 70 through No. 87 <br />will be installed above proposed mine workings adjoining the old east <br />portals. Monuments No. 90, 92 & 93 have been installed above the <br />proposed underground workings adjoining the new West Portals. <br />A number of high-resolution, closely spaced subsidence monuments have <br />been installed in sites selected throughout the existing permit area. <br />Monitoring stations No. 201 through No. 224 are installed above <br />projected fault traces in an attempt to discern the effects of <br />differential subsidence between alternating fault blocKs. Stations <br />No. 42 through No. 51 are located in areas of thick overburden. <br />stations No. 28 through 41, in contrast, have been installed above <br />overburden thicknesses considered typical throughout the permit area. <br />The high-resolution subsidence data will be used to evaluate and <br />further define the projected angle of draw. Data collected from these <br />monument grids will allow verification, or support redesign, of the <br />subsidence control plans proposed by the operator for implementation <br />in the future. <br />COVCC.submitted Technical Revision No. 16 to the Division in October <br />1991. The revision allowed COVCC to temporarily discontinue <br />subsidence monitoring over inactive portions of the original mine, <br />which have been sealed since 1986. Annually submitted subsidence data <br />has indicated that the area has stabilized. The Division approved the <br />revision February 11, 1992. <br />The subsidence portion of the application is in compliance with the <br />Regulations. <br />XVI. Concurrent Surface and Underground Mining <br />This section is not applicable to the Orchard Valley Mine. <br />XVII. Operations on Alluvial Valley Floors <br />The discussion of Alluvial Valley Floors can be found on pages 5-6, <br />Section 2.06 of Volume l; in the AVF Appendix A, Volume 4 and in the <br />Geo-Hydro Phase 2 studies. <br />-42- <br />