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• roof bolts to support the mine roof strata. Roof bolts are typically <br />installed on five (5) foot maximum centers. EFCI also operates radio <br />remote-controlled continuous miners which extend the allowable depth of <br />cut to approximately 40 feet. <br />Roof bolts are installed according to an approved roof control plan which <br />is included in Exhibit 16, Roof Control Information. In addition to roof <br />bolting, maintenance of barrier pillars along haulageways and at property <br />boundaries, and controlled recovery are critical components of EFCI's roof <br />control plan. A detailed discussion of ground control measures is <br />presented in Section 2.05.6, Mitigation of Impacts of Mining Operations, <br />under the subtitle, "Subsidence Survey, Subsidence Monitoring, and <br />Subsidence Control Plan". <br />Mine Ventilation. In sequence with progressive advance of the coal face <br />and development of cross cuts, ventilation systems including stoppings, <br />• brattice cloth and overcasts, where necessary, are established or moved <br />to maintain a consistent volume of fresh air at the coal face. The mine <br />ventilation system is designed and maintained to control coal dust and any <br />methane gas which may be present and to provide sufficient fresh air to <br />maintain a healthy working environment. Details of the Southfield <br />ventilation plan are presented in Exhibit 17, Ventilation System, and <br />Methane/Dust Control Plan. <br />Mine Drainage and Dewatering. As described in Section 2.04.7, Hydrology <br />Description, the only significant source of groundwater in the Southfield _ <br />mine area is groundwater which has collected and is stored in the numerous <br />abandoned underground mines. As mining operations progress, subsidence <br />may result in fracturing of overlying units establishing hydraulic <br />connection with these old workings. EFCI has experienced significant <br />inflows as mining has progressed into new development areas. Generally <br />these inflows subside over time as flows from the abandoned mine areas <br />decline due to localized depletion or partial sealing of the fractures by <br />• sediment deposition. <br />2.05.3-11 <br />