RI 9151 - Cost Comparison of Gob Hole and Cross-Measure Borehole Systems To Control Methane in Gobs

The capital investment and operating costs of two methane-control systems used during longwall mining operations are compared in this Bureau of Mines report. Costs are given for a surface gob hole drainage system and an underground cross-measure borehole drainage system to control methane gas in gobs in four coal mining areas--central Pennsylvania, northern West Virginia, southern Virginia, and northern Alabama. Present-worth analysis is used to determine the more cost-effective alternative in each location. The alternatives have equal lives and provide the same service based on a minimum rate of return of 15 pet. In central Pennsylvania and northern West Virginia, the gob hole system is more cost effective than the cross-measure system, by 10 and 18 pet, respectively. In southern Virginia and northern Alabama, the cross-measure system is more cost effective, by 29 and 38 pet., respecitively. Costs for other locations must be developed on a case-by-case basis.