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JCr LU dtS JJfI ly .Sb John h R6ol Jr <br />"D" 6cam/Dear Crask Impact <br />FAK NC. 3032782163 p. ~: <br />Daq• 3 Saptombar 21, 1Q4R <br />• Kenny 11969) remotely measured the height to the collapsed <br />arch following longwall faces in Great Srltain. xe stated that the <br />maximum height was four times the longwall mining height, which <br />would be 49 feet for the planned 12-toot maximum mining height for <br />the "D" Seam longwall panels. <br />Penq (1992) stated, "After the extraction of coal, the immedi- <br />ate roof caves irregularly and !ills up the void. The strata in <br />this zone not only lose their continuity completely, they also lose <br />their stratified beddinga. The coved zone is noxnally (2 to 8)m <br />high {whar• m ~ mining hwight) depending on the properties o! the <br />immediate roof and the overburden." Penq~s recommended range for <br />the haight o! th• caved zone would by lrom 74 feet to 9R iwwt for <br />the "D" Seam 12-ft maximum mining height. <br />The data available for caving of the immediate root above <br />longwall panels suggeets that 48 fact i• a conoorvativo prediction <br />for caving above the planned 12-loot maximum mining haight for the <br />OnLuw -D" Seam largwall panels. Therelore there is no possibility <br />for water in Hear Creek, when water is occasionally !lowing, lrom <br />being captured by a wllaps• chimney breaohinq the ground surface <br />minimum o! 300 to 400 feet overhead. <br />F[tACTVRE RACK HEIGHT AZ;OVE PANEL ROOII' <br />• The Only possible water l0es Or water from Bear CYCek ie by <br />percolation through the Practured rock sons immediately above the <br />caved rock zone, indicates on Fiqur0 7. Tna rraCtured zone Cverly- <br />inq the caved immediate rack zone is characterized by rook fractur- <br />ing and tissurizntion the decrease upward above the caved zone. <br />Bedding continuity is not aPlected in the fractured zone, i.e. <br />there is no apparent ditlerantial rotation of the bedding surfaces. <br />Tho porosity and permeability of the fractured rock zone is <br />increased because of the lracturinq. Permeability rands to <br />decrease upward through the lractured zone. <br />Schulte (1957) located the maximum identilfable height of the <br />fractured rock zone ea nin• times the aiainq height above the <br />nri?inwl roof of thw longwall panel. Thle would amount to nn <br />increased permeability zone to a height of 108 feet above the <br />original longwall papal root in [hs caa• of t.hw maximiue 12-font <br />planned "D"' Seam longwall mining height. <br />Pang (1992) states that, "The combined height of the fractured <br />rope and the caved song ie in general (20 to 30)m (whoro m - mining <br />height). The height of the fractured zone !or hard and strong <br />strata is larger than that :or soft and weak ones."' Tho rosultinq <br />prediction is that the combined caved zone plus the fractured zone <br />will be lrom 240 to 360 Teat above the longwall papal root for th• <br />u <br />