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1.0 Previous lnvestieation and Site <br />2.0 MINING AND OIL AND GAS DEVELOPMENT <br />2.1 MINING DEVELOPMENT <br />Mining in the area was preceded by the attempted development of the area known as the "second <br />right." This area is located south of the affected area. This area was first developed in January <br />1988. During the development, a geologic anomaly was encountered that forced abandonment of <br />the area. <br />A series of fault iocation holes were drilled to attempt to locate the magnitude, direction, and <br />extent of the fracture zone. A fault was not interpreted from the results of this program; however, <br />a structural downwarp, similar to a monocline, was inferred. The monocline appears to decline at <br />a rate of 8 percent to the east over a distance of 400 feet. The fractured zone was interpreted to <br />trend north-south at 6,600 feet above mean sea level (AMSL). For reference, the surface of the <br />Purgatoire River is at 7,010 feet AMSL, making a fracture zone approximately 410 feet below <br />surface grade at the location of the second right development. Permanent seals were emplaced to <br />separate the fracture zone from the mine. In addition, vent wells were installed into the second <br />right development, and methane has historically and is currently being extracted from the wells. <br />After the second right development was abandoned, development of the mine was turned north <br />under the Purgatoire River. Development of entries under the river began in 1989, and the first <br />longwall panels were mined on the north side of the river in 1993. A ventilation shaft was installed <br />for Chese activities in late 1989 and early 1990. Mining at the site ceased in December 1995. <br />After mining ended, pumps at the mine were deactivated and the mine is currently ftlling with <br />water. In addition, gas is recovered from the mine by active ventilation. The mine is therefore <br />maintained under negative pressure. <br />2.2 NATURAL GAS DEVELOPMENT <br />Gas development at the site has focused on coal bed methane (CBM). CBM is principally extracted <br />from wells installed in coal seams [hat contain high volumes of gas. The methane is liberated by <br />extracting of water from the coal seam via the well, resulting in decreased pore pressure in the <br />coal. Typically, methane is then collected from the wells and piped to compressors, and then to <br />consumers. <br />Two CBM wells exist at the site. These wells are known as Picketwire 28-10 and Picketwire 28- <br />11. Picketwire 28-10 is the eastern well at the site, and Picketwire 28-11 is the western well at the <br />site (Figure 1). Well 28-10 was spudded on September 24, 1990, and We1128-11 was spudded on <br />October 25, 1990. <br />Well reports for Well 28-10 indicate that the ground level at [he site was 7,018 feet AMSL. The <br />well was first drilled by emplacing a surface casing (conductor) by drilling with a 17 1/2 inch bit <br />Meth-(292)-11-02.doc, l I/20/2002 18 <br />