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TWENTYMILE COAL COMPANY <br />FOIDEL CREEK MINE (PERMIT C-82-056) <br />FIRST-HALF 2006 SUBSIDENCE REPORT <br />RESPONSE TO CDRMS COMMENTS - 01/07 <br />Item 1-Please add a line that traces the limit of the effects of the angle of draw at the east end of Panel <br />19-Right to demonstrate that Fish Creek was not affected by nearby longwall mining. <br />Resnonse: The "Subsidence Map -First-Half 2006" has been revised to include a line identifying the <br />calculated limit of subsidence, based on mining depth and angle-of--draw. Copies of the revised map <br />accompany these responses. Fish Creek intersects the zone of anticipated subsidence, as indicated by the <br />subsidence limits. Projected and actual subsidence of the creek in the area of the 19-Right Panel was, <br />however minimal, given that the creek alignment overlies the entries at the end of this panel, where pillars <br />were retained to provide long-term support for the mine bleeder (ventilation) system. The text of the <br />"First-Half 2006 Subsidence Report" has been reviewed and revised to clarify subsidence considerations <br />in this area. <br />Item 2 - In the information requested under Rule 2.05.6(6)(c)(i)(E) below, please report the date that <br />baseline survey(s) of the monuments ware accomplished. The text of the report indicates that survey data <br />had been collected daily starting in May. The Subsidence Map indicates longwall mining underway (east <br />end of Panel 19) in May. <br />Resnonse: The referenced text was in error. Baseline surveys for the powerlines were completed by <br />September 14, 2005, approximately 8 months prior to mining of the azea. The text of the "First-Half 2006 <br />Subsidence Report" has been reviewed and revised to correct this error and clarify the timeframes for <br />monitoring and mining. <br />Item 3 -Please add the location of each monument to Map 23B, with reference to it on page 2.05-191.6 <br />of the PAP, and the location of each monument on the Subsidence Map of the report. <br />Resnonse: The "Subsidence Map -First-Half 2006" has been revised to show the locations of the <br />subsidence survey monuments. Copies of the revised map accompany these responses. <br />Given that the PAP text adequately describes the subsidence monitoring program, that the semi-annual <br />Subsidence Monitoring Report (which includes the Subsidence Monitoring Map) is a requirement of the <br />Permit, and that the Subsidence Monitoring Report provides adequate information for CDRMS review <br />and evaluation of compliance with permit and applicable regulatory requirements, inclusion of a listing of <br />subsidence monuments in the PAP text, and the addition of monument Locations to Map 23B is <br />unnecessary and redundant. <br />Item 4 -Please report the monitoring measurements made in the information requested under Rule <br />2.05.6(6)(c)(i)(D) below. <br />Resnonse: Monitoring data demonstrating compliance with both the quarterly monitoring requirement, <br />and the requirement to commence monitoring at least one month prior to initiation of mining beneath a <br />monument or structure, is provided in the accompanying spreadsheets. <br />