Laserfiche WebLink
Page 7 <br />Carol Russell <br />April 8, 1982 <br />4.6.4 Subsidence Control Plan <br />4.6.4.1 .B Extent of Planned Subsidence <br />Table IV-IO presents minimum and maximum overburden depth:a for various <br />structures and areas of the mine plan. There appears to ,Se an error in <br />either the minimum depth stated for the oil pipeline (390 feet) or the <br />minimum depth stated for the third east entry of the b5 mine (120 feet), <br />because the two appear on the map to be relatively coincident. <br />The applicant observes; "The mine area is not marked at tiie surface by <br />any prominent faulting." (Page IV-126) However, the mine maps for the <br />Wise NiII b3 Mine on file at the Colorado Bureau of Mines office indicate <br />that the northeast boundary of the mine was determined by a fault truncation. <br />This fault appears to coincide with the face cleat orientation indicated on <br />map IV-11 within the NS mine in the same general location.. Furthermore, map <br />IV-II indicates that the highest mine inflow rate encountered within the <br />NS mine occur within the same general location neighboring the fault. These <br />coincidental occurrences suggest that significant fault involvement with <br />inflow rates may exist. This would be of particular concearn in evaluating <br />potential effects of the mine plan upon the overlying Yampa and Williams <br />Fork Rivers. <br />The applicant observes on page IV-I29 that; "Subsidence iii the Eagle Mine <br />Complex area should be approximately 70e of what would be predicted by the <br />NCB and 85~ what would be predicted as the York Canyon Mine." Until this <br />point in the subsidence presentation, the applicant has been forwarding <br />qualitative projections of the effect of factors such as i:opography, overburden <br />thickness and overburden lithology upon the magnitude of~e:ubsidence observed <br />however, without supportive references, data or narrative, a quantitative opinion <br />is interjected at this point. Appropriate supportive references, data and <br />narrative should be included to justify this quantitative projection of <br />subsidence magnitude. <br />4.6.4.Z.C Predicted Subsidence Results <br />The second paragraph of page IV-131 refers the reader to map IV-7 ,for an <br />indication of the areas in which subsidence is planned to occur. I believe <br />the proper map reference would be map IV-1. <br />4.6.4.2.A Anticipated Affects of Planned Subsidence <br />The applicant observes that no material damage is projected for "renewable <br />resource Lands existing in the mining area not exempt front the performance <br />standards." (Page IV-133) In this regard the applicant's attention is <br />directed to the letter from Edward L. Bischoff to Mr. Andrew P. Schissler, <br />dated February 4, I98I. <br />(cont'd) <br />