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1994 Subsidence Report <br />Page 2 <br />Ribs: Rib were fair under cover less than 1600 feet. Rib were poor <br />in areas with cover over 1600 feet. <br />Floor: The lower "D" seam was used as floor which provided competent <br />conditions. <br />Anomalous Conditions: <br />Small seeps from both roof and floor sources were encountered <br />throughout develolanent of the section. <br />1st East Mains <br />Mined length: Approximately 1,700 feet of panel advance. <br />Overburden Thickness: <br />Varying from approximately 1,250 to 1,500 feet. <br />Mining Height: 9-11 feet on advance. <br />Roof: Comprised of mudstones tending to air slack. Top coal of 2-3 <br />feet in thickness was left on the roof to prevent problems <br />associated with this strata type. <br />• Ribs: Ribs were fair. <br />Floor: The lower "D" seam was used as floor which provided co~etent <br />conditions. <br />Anomalous Conditions: <br />Small seeps from both roof and floor sources were encountered <br />throughout develop:rent of the section. <br />Panel X <br />Mined Length: Approximately 2,000 feet of panel advance. <br />Overburden Thickness: <br />Varying from approximately 1,400 to 1,600 feet. <br />Mining Height: 9-11 feet on advance. 15-18 feet in retreat in pillared <br />areas; maximum 16 feet on retreat in partial extraction <br />areas. <br />Roof: Co~rised of midstones tending to air slack. Top coal of 2-3 <br />feet in thickness was left on the roof to prevent problems <br />associated with this strata type. <br />Ribs: Rib were fair. <br />• Floor: The lower "D" seam was used as floor which provided cronq~etent <br />conditions. <br />