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JIM TRTUM 8 ASSOCIATES TEL=7 995-7191 <br />tli~J~. 1'Jyi l: ~. I..~.i .l..~i~.~........ <br />MEMO: <br />TO: Dr. Kohl <br />Fli,OMt C.E. Gerity ~~t~ <br />May 24.~ 518 No .007 P.10 <br />DATEr May 18,1995 <br />BZJB.lEC1: Subsidence Ovor Limited Extraction Room and Pillar Mining at the <br />A110n mine. <br />Oa Friday May 12,1885, I visited with Jack snow ,the retired Mine <br />Superintendent of The Alien mine. Mr Snow is an Engineer and was employed by <br />CF&I during the time of the Woodward-Clyde study. ]3e recalled the study, and said <br />there had bees no other studios of the mines while ho was there. <br />Some ofthe points that he made while talking to trim~were: <br />The Woodward- Clyde methodology and procedures were very good, He would <br />sot challen8e the survey data. _ <br />The Allen mine had serious problems with faulting and roof falls. The room and <br />pillar panel in the' Woodward-Clyde study was cne of those areas. To be able to <br />manage this problem in this section gad in many other sections of the mine, they <br />would typically use a mining technique that ha refbaed to as development, a . . <br />room sad pillar system with narrow olrenings, to follow the coal. Thera was no <br />retreating and the extraction wee linuted. <br />• Some of the room and pillar eeclione with development mining subsided. The <br />most notorious was a opening along the State highway. (Several local residents <br />had told me of this problem, but I did not know that it was over a room sad <br />pillar limited extraction section) ' <br />• He said there were many failures is tiro mine that effected the sur~o6 along the <br />Purgatoire River valley, sad that they were very concerned at tho ti>,ap. Thew <br />were all over limited extraction mom and pillar areas. He indicated that the <br />surface ercpressions are subtle and an observer would have to know the mining <br />erase to make the connection. <br />Oa Mande~y Me~y 15 I was able to review sad have copies made of some of the mine <br />maps of the Alien mine that are on Sle with the state. <br />Map A includes the section just is the we~E of Section 2 South, tl+om this it to clear <br />t3rat Figure 32 in the Woodward-Clyde report.ROttraliy indicates the anal mice <br />conSg<ttatioa. You are correct in noting thatkurface monument 3.1 ties over a <br />section that vrae mined out probablywin~.a.retreat system. However all of the <br />othos points overlie either entries`vith wide pillars, limited extraction development <br />mining with wide pillars, or no extraction at all. If a line were drawn from the odge <br />of the retreat mining area at a oonasrvative-angle of:intluenoe of 35° it would <br />intersect the ground surBaoe at about monument 8-8. Measurable eigaiffcant surface <br />movement occurs to oast of this monument, that can only be attributed to <br />ezoavation in room and Pillar areas with wide pillars. <br />ProNSSwrNS ICNarrvssRrna 4wssanfU,.,st. <br />CON•iliTINO SNOIN[iR• LiEO~efay L2760l1S <br />'!.'.wN.hrY'.'Na."`^l'gC.IR~.~_ - .ear <br />