Maps illustrating an investigation of barrier pillars in the Western Middle field as part of the comprehensive study of mine-water problem in the anthracite region of Pennsylvania. Scale 1:4,500 feet. Included in the set is a graph (Figure 8) showing the relationships between pumping loads in the anthracite region of Pennsylvania with altitude on the x-axis and distance (in miles) from the Conowingo Portal on the y-axis. An explanation of the graph in Figure 8 (Figure 9) summarizes data from Bureau of Mines Technical Paper 727, Report of Investigations 4700, and Bulletin 513.