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iiiiiiiiiiiiiiiiiii <br />STATE OF COLOI~~DO <br />Roy Romer, Governor <br />_ %) <br />DEPARTMENT OF NATURAL RESOURCES %, ~~,, <br />MINED LAND RECLAMATION DIVISION (.~~~,'~,,~ ~~, <br />FRED R. BANTA, Dlreetor ~~~ <br />r~~ <br />DATE: January 19, 1989 ,- <br />T0: Susan Mowry '~ `"~~ <br />FROM: Jim Pendleton ~~"`" <br />RE: tot. Gunnison No. 1 'i-Annual Subsidence Monitoring Data Report <br />(Permit #C-80-007) <br />Mt. Gunnison No. 1's semi-annual subsidence monitoring data report documents <br />that residual subsidence is continuing to occur above conventional panels 1W1S <br />and 1W2S. Extraction was completed in panel 1W1S in February of 1987 and in <br />panel 1W2S in October of 1987. The rate of subsidence has decreased slightly <br />during each subsequent six month monitoring period, All of this is in keeping <br />with characteristic ground subsidence experience in Colorado. <br />The data report also includes the water level monitoring record for monitoring <br />well 38-H-1, installed above panel 1W1S five years prior to retreat extraction <br />within the panel. During retreat extraction of panels 1W1S and 1W2S the water <br />level in Well 38-H-1 fell from an elevation of 7,480' to 7,367', a significant <br />decline of 113 feet. Following completion of retreat extraction in the two <br />panels the water level in Well 38-H-1 rebounded by 106' to an elevation of <br />7,437'. Tnis recovery water level falls within the background water levels <br />recorded prior to commencing retreat extraction in panel 1W1S. This presents <br />verification of Mt. Gunnison's original permit application PHC projection that <br />subsidence would have only a transient impact upon the ground water hydrology <br />of overlying strata. <br />I recommend acceptance of the semi-annual subsidence monitoring data report. <br />Once again, I would like to compliment West Elk Coal on a subsidence <br />monitoring job well done: <br />cc: Mike Long <br />215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />