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located in the upper reaches of this draw. COVCC submitted, to the <br />Division, a signed copy of a water .replacement plan agreement between <br />COVCC and Stucker Mesa Domestic Water Company (see permit application, <br />Volume lA, Section 2.05.6, pages 98A to D. <br />Subsidence Monitoring Program - <br />COVCC maintains a subsidence monitoring program with three components; <br />visual inspection, wide-spaced grid subsidence monumentation, and a <br />Pitkin Mesa Pipeline subsidence monitoring survey. 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. Additional 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 />Monuments 94-99 have been established to monitor subsidence impacts <br />resulting from mining operations in the West Coal Pad, scheduled for <br />years 1993-97. <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 />High-resolution subsidence grid data, required during the previous <br />mining permit terms, is used to evaluate and further define the <br />projected angle of draw. Data collected from these monument grids <br />will allow verification, or support redesign, of the subsidence <br />control plans proposed by the operator for implementation in the <br />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. This revision dropped the entire <br />high-resolution monitoring grid and several of the wide-spaced <br />monitoring locations from the subsidence monitorin plan due to their <br />apparent cessation of active subsidence. Annually submitted <br />subsidence data has indicated that the area has stabilized. The <br />Division approved the revision February 11, 1992. <br />-42- <br />