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ffi~ 96-90, 96-91 <br />developed using "our subsidence prediction model" and utilizing the ' <br />appr'oodts>ate "35-degree angle of draw yvu suggested to sre:" <br />As Our original calculations indicate, using the actual <br />extraction ratio, extraction thidmess, and percent hardrnck <br />from the ~olo3ical maps, subsidence wOUld not occur. <br />In ozder to Obtain an angle of draw of 34.52 degrees, <br />we had to dOUble the extraction thic]meass (to 15 feet), half <br />the percent hardroc]c (to 15t) asyi assume 100 extraction (ver- <br />sus 314) . The calas]ations are shown cos the attachet2 cuter <br />printout. As you can see even with this theoretical situation, <br />the subsidence ovuld be less than anone-eighth of an inch. <br />We noted that usx)ex this scanari0 that the *a; ~ **~ would have <br />ds:opped 9.11 feet as it is,located, at, the os~ter-of the subsi- <br />dence curve.. We .found sio evidaice in the' field indicatissg that <br />the railroad tracks had subsided. (3/] <br />The Tatums hired two ps:+ofessiona]. engineer's to assess the conditions <br />at their residence. Follarsisrj a visit on February 23, 1995, William J. <br />Attwooll, P.E., Vice President of ?~,;*re l ~inmrr., Inc., prepared a <br />doaanertt far the T3tums, dated [43zYls 16, 1995, and entitled "Report of <br />Site Visit CEssersations Tbtum Fsidence." TYlerein, he described his Cbser- <br />vatiass of danage to the issterior airs exterior of the residence. He dis- <br />cussed possible causes of the dartage and summarized: <br />C17he Tatum residence has been da<saged by settlerent ar dis- <br />placetsiasts that are primarily evident in the two-story portico <br />~ In BC~31d.N~37.t~, 130 IfIIA 260, 262-63 n:6 (1994), we stated: <br />"'Atsgle Of draw' is defined in 1 ~_ _ Mi ni r,rr g~q; n~~ F .+riFw+ir <br />§ 13.1-1 (1973) as 'the angle begs a vertical liras fzTrnn the edge of the <br />[mine] opening and another line exterr3ed to a point at which subsidence <br />tall8 OUt t0 2er0.' Ilse HaI1C~(70dC StdteS fitrthor; <br />'This arsgle has been faari to be abort 35° irs SUrnpe but is rather <br />academic, being a funCtical of instnarent grecisioa in detecting subsidence. <br />Sinoe the subsidence effect is an small at any point beyond a 25° able, <br />this latter may be considered the practical limit of subsidence. Fuzttser- <br />mae, indications are that the able of draw varies with depth affi nature <br />of the strata.' <br />(Footnote omitted). . <br />'Aisgle Of dtaa' iS aL60 defined ill aDit~rinrwn,. pf 'Wino. 'r+pral <br />U.S. Department of the Interior, Bureau of Muses 39 <br />(1968), as: <br />'7n coal mine subsidence, this angle is assumed to bisect the angle <br />between the vertical and the angle of s:epose of the material asrl is 20° for <br />flat seams. For' dippisxJ seams, the angle of break increases, being 35.8° <br />frtnsthe vertical fora 40° dip. The main break occurs over the lean at <br />an angle frays the vertical equal to half the dip.'" ,~ M & ~7 ~ ~a. v. <br />~, 115 IffiA 8, 21 (199D) . <br />15]:,,IEQA. 293,..1 <br />