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Subsidence F,etd Observations <br />West Elk Mine <br />August 2729. 2002 <br />4.1.6 Traverse F-F' <br />I he Iravcrsr begins at point F.' of truverre L-li' ;tnd cods at Drill Sitc IZAV-II1. <br />• (A•crburden depth ranges Inim 2,050 to 2:20(1 fl above the 13-ticam. <br />• Nu subsidence-related cracks were observed along traverse, except those at Location 2. <br />I_ocatian ?: <br />Point is located ISf1 to 200 It cast of Drill tine R:1V-IU. A nunheast-trending, crenulatc <br />subsidence crack. ;'. to '/: inches wide and b to K 11 long occurs at this point. This crack was nut <br />present last year, when the longwall Pace moved beneath it. The crack Wray fx a residual mining <br />rlliYt clue to stns, rradiuslmcnts (sec vida+ li+r mare Jclails). <br />Location 3: <br />Anorth-trending swulc is hrcated at this point. The swalc is alx+ut I.S Il dcrp, as much a+ 5 ft <br />wide, and 80 11 long (I'igurc'_). Crteks as much as IU inches wide locally occur near the Swale <br />margins. ;1t the lime of observation. the ratio of'suhsidence to construction cause was believed <br />to Ix ulxrut 7fW,'o/?(1°10. I,uter, it was determined that this was the site al'u mud pit and extensive <br />construction activity. Now, the ratio of subsidence to construction cause is believed to be morn: <br />likely .U°,'~l7U°ro. <br />......_ _ i ~I;urc :. A north-trcndinG Swale with cracks wt the <br />... <br />- ;~' ~~~ar~ins. 'The came may Ix primarily rclaltal to <br />~~m~truclion ncli. iti~~ nt the nenrM~ drill au. <br />:sir --14E.~$:. {.F•.; t'" ~_ ~_.C ~-. <br />Ate. • " y~A~ ~~! <br />,~'r t :~~~ ± Y: <br />- T f~ .IJ-w. - <br />831-D32 570 Wrlght Water Engineers, Inc. Pager 10 <br />December 2002 <br />