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., ininq Histor The underground Golden Eagle mine utilized longwall and room-and-pillar methods to mine the Maxwell Seam. Mining stopped on the 1 North entry, closest to the Tatum Ranch, in May 1988 because of operational problems and the decision to use the 3 North to drive north beneath the Purgatorire River to the longwall panel. The 1 North entry was sealed and has since flooded. The mine plan in the vicinity of the Tatum House is a room-and-pillar type of operation. The pillars are 80-foot square, the entry is 18-feet wide, and the void is 7.5-feet high. The percentage extraction of coal in this entry is calculated to be 34.04 percent. Minincx-related Subsidence Potential Using the Surface Deformation Prediction System (SDPS), Pillar Stability program, the safety factor for pillar failure was calculated for the 1 North entry area closest to the Tatum residence (Table Z). The Holland-Gaddy (H-G) Safety Factor is 2.3. It is generally considered that a H-G Safety Factor greater than 1.5 will give long-term protection against pillar crushing and accompanying surface subsidence. The SDPS Surface Protection Program was run to delineate the mining configuration which would protect the surface from subsidence (considering 50 percent extraction of the coal under the structure). This is an industry-standard method for determining the area in the mine required to provide adequate protection of the sufrace from underground mine subsidence. The surface protection area is typically established by measuring 15 feet out from the structure and projecting a 15-degree angle from the vertical down to the coal seam. Within this defined area, 50 percent of the coal can be extracted if the calculated H-G Safety Factor is greater than 1.8. For the evaluation of the Tatum complex, it was assumed that the total Tatum House and garage to be 80 feet by 80 feet and required 15 feet was added to this block. Figure 3 is a cross-section (A-A'on Figure 4) from the center of the mine entry to beyond the Tatum complex. The SDPS Profile Function model was used to predict the effects on the surface under a scenario more likely to cause surface effects. For this calculation 11 percent hard rock, and 75 percent extraction were the input parameters. In fact, the actual hard rock composition of the overburden is closer to 50 percent (Figure i). Actual calculated extraction is 34.04 percent (Table 1j. 4