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._ t (c) Monuments 813 through B18. Monitoring to commence no later than when the longwall face is 63o ft from the monument line. (d) Surface 'crack" mapping of subsided surface areas. 2.2 Quarterly monitoring, 2 East Longwell (a} Line "S", monumeets S1 through S6. Moni.toring to commence no later than when the longwall face is 800 ft from monument line "S". (b) Line "B", monuments B1 through B18 and anew B-line monuments. Monitoring to commence no later than when the longwall face is 630 ft from they monument line. (c) Line "A", monuments Al through A18. Monitoring to commence no later than when the longwall face is 630 ft from the monument line. (d) Surface "crack" mapping of subsided surface areas. 2.3 Initi al and final monitoring, 2 East Longwell (a) Initial survey of Lines "C" and "D^ when the longwall face is approximately 630 ft from monument C13. (b) Final survey of tines "<"' and "D' sit months after longwall mining of the 2 East Panel is completed. 3.0 Data Analvsis This proposed program will provide data for determinations of subsidence response due to undermining of F-seam room-and-pillar workings and longwall panels by E-seam longwall miming. The data from subsidence monitoring of the 2 East longwall panel will be used to calculate two draw angles and to provide an estimation of maximum subsidence for E-seam longwall mining under F-seam, room-and-pillar workings. These results will be based on an overburden range of 250 ft to 500 ft and inter4uxden range of BO ft to lOD ft. The data from subsidence monitoring of the 1 East longwall panel will be used to calculate one draw angle and to provide an estimation of maximum subsidence for E-seam longwall mining under F-seam longwall panels. These results will be based an overburden range of 800 ft to 900 ft and an interburden range of 90 ft to 100 ft. c