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Over approximately 400 feet of • development of this submain oa:urred in September, 1987. Surveys were initiated on an annual basis in 1988 arc] have continued to date. No significant subsidence is evidenced by the 1991 survey data at this location. Visual Monitoring 1991 Visual subsidence monitoring is aooon~lished by periodic "walkovers" of recently mined a7"PaR within the present permit area. Walkovers are generally done in wnjunction with survey monitoring due to the s~sonal accessibility of the area. Visual monitoring is concentrated Over arxaaa of retreat mining with particular er~hasis on areas mined order low Overburden. A visual subsidence monitoring inspection was conducted in May of 1991. Panels H and G were inspected. Panel G advance was oce~g~leted in October, 1988. Retreat minim was o®~leted in July, 1989. Panel H advance was completed in March, 1990. Retreat mining was owig~leted in Sept®nber, 1990. No visual indications of subsidence were noted during the subsidence inspection. No visual indications of subsidence were noted during surveying or hydrology monitoring efforts for the 1991 calendar year. • Projected Subsidence Eaq~acts 1992 Subsidence impacts during 1992 are projected to be minimal based upw~ subsidence patterns established to date. Mining during 1992 is projected to occur in panels A+, B, Z, and either C or I. Development and retreat mining is scheduled to occur in panels A+, B, and either C or I while development mining only is scheduled for Panel Y. Continued development mining of the II West Submains west of the III South Submains is projected as well. None of the areas scheduled to be mined during 1992, with the possible exception of Panel C, are significantly different fran areas previously mined in terms of depth, topography, geology, or mining technique and should not, therefore, exhibit significantly different subsidence effects. Panel C lies in an area of relatively low cover (300 to 800 feet) and is projected to be mined utilizing a partial extraction mining method intended to preclude the occurrence of subsidence. the development of Panel C remains uncertain at this time due to regulatory constraints but is actively being pursued. Projected Subsidence Monitoring 1992 Per the conditions of technical revision 16, ~VCC is required to inform the Division of selected sites proposed for surveying for the upcoming year in the Annual Subsidence Report. For the 1992 Calendar year, COVCC proposes the following sites for surveying (see Map No. 2-5 appended to . this report): 6, 7, 8, 14, 15, 16, 88, 94, 95, and 96. Should Panel I be mined in lieu of Panel C, sites 91 and 92 will be monitored as well. 4