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e . - ,~. <br />FIRST-HALF 2006 SUBSIDENCE REPORT <br />I. Survvev Data• <br />During the first-half of 2006, mining began in the 19-Right Longwall Panel, which lies <br />beneath and parallel to two powerlines, owned by Western Area Power Administration <br />(WAPA) and Tri-State/Public Service Company of Colorado. A baseline survey of the <br />powerlines was completed by September 14, 2005, prior to initiation of mining activities. <br />Starting with initiation of mining in the 19-Right Panel in May (and prior to undermining <br />the powerlines), survey data has been collected daily for the bases of each supporting <br />powerpole as the longwall continues to mine east to west. Surveys of the powerpole <br />structures will continue until mining in the 19-Right Panel is completed. Visual <br />inspection of the structures will continue on a monthly basis for 3 months following <br />completion of mining. <br />II. Structures: <br />As noted above, starting in May 2006, mining in the 19-Right Panel has subsided two <br />powerlines from the eastern-most powerpole, 145-1. Twentymile Coal Company <br />personnel complete daily surveys of the powerpole structures, and will continue the <br />surveys and associated reporting to both the CDRMS and designated representatives for <br />the powerline owners through completion of mining in the 19-Right Panel. In <br />conjunction with the powerline surveys, Twentymile Coal Company personnel also <br />conduct daily visual inspections of the subsided powerpole structures. <br />Structures remained essentially unaffected during the reporting period, with the exception <br />to predicted impacts to the powerlines over the 19-Right Longwall Pane]. <br />III. Ma°: <br />Monitoring locations for the first-half of 2006 aze shown on the First-Half 2006, <br />Subsidence Map. The map also indicates the location of the longwall face on a monthly <br />basis and the projected subsidence limits, based on mining depth and angle-of--draw. <br />IV. Vegetation Monitoring: <br />Vegetation monitoring (riparian survey) for the 16- and 17--Right Panels was performed <br />during athree-day period from August 30, 2005 through September 1, 2005. The <br />vegetation monitoring report, which evaluates any changes in riparian vegetation <br />conditions and characteristics for Fish Creek, relative to the measured baseline <br />conditions, is presented as an Appendix to this report. <br />2006_1stI-IaltSubReportRl.doc Page I oft 12/18/2006 <br />