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FIRST HALF 2007 SUBSIDENCE REPORT <br /> <br />I. Survey Data: <br />During the first half of 2007 survey data was collected for the powerlines, owned by <br />Western Area Power Administration (WAPA) and Tri-State/Public Service Company of <br />Colorado. These powerlines lie above and pazallel to the 19 Right longwall panel as <br />shown in the First Half 2007 Subsidence Map. Starting in May of 2006 thru May 2007, <br />survey data has been collected on a regular basis for the bases of each supporting <br />powerpole. <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. Mining in 19 Right was completed <br />on February 9a` of 2007. A baseline survey on the powerlines was completed September <br />14, 2005. Daily surveys of the powerpoles have been performed by Twentymile Coal <br />Company personnel through May of 2007 and reported to designated representatives for <br />the owners of the powerlines. Also, continued visual inspections of the subsided <br />powerpoles have been performed daily by Twentymile Coal Company personnel. <br />• Structures remained essentially unaffected during the period, with the exception to the <br />predicted impacts to the powerlines over the 19-Right longwall panel. <br />III. Map: <br />The monitoring locations for the first-half of 2007 aze displayed on the First Half 2007, <br />Subsidence Map. The map also indicates the location of the longwall face on a monthly <br />basis. <br />IV. Vegetation Monitoring: <br />Vegetation monitoring (riparian survey) for the 16- and 17--Right Panel 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, was presented as an Appendix in previous subsidence reports. <br />V. Hvdrolotric Monitoring: <br />During the first half of 2007, water quality data was collected from established sites along <br />Fish Creek in azeas underlain by gate-roads or longwall panels, as well as from <br />representative downstream sites located away from the subsidence azea. <br />~I <br />2007_1stHalfSubReport.doc Page 1 of 2 6/18/2007 <br />