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6(a)). This incident occurred in the Maxwell seam approximately 1500 feet horizontally from the area of <br />methane contamination. <br />Drilling on coal bed methane well 28-10 commenced on September 24, 1990. This well is the eastern-most well <br />in the Toupal pasture. Drilling on well 28-11 commenced on October 25, 1990. The target far each of the wells <br />was the Vermejo formation coals located some 1000-1500 feet below the surface. Surface casing was set on <br />each of these wells between 500-600 feet in depth. Loss of circulation of cement and other factors documented <br />in the written record clearly indicate improper completion (poor cementation of casing) of well 28-10. Methane <br />at 20 pounds per square inch (psi) was measured in the Bradenhead valve as recent as the day prior to <br />abandonment of this well. This well was located as close as 150 feet from soil monitors which returned <br />methane values in excess of 90°~ in the soil. <br />Two significant events have occurred since the monitoring of methane in the soils began in March 1999. First, <br />both coal bed methane wells in the Toupal pasture were cemented and abandoned in October 2000. Second, in <br />October 2001, the mine workings flooded above the elevation of the development entry that encountered the <br />methane/water charged fault (6758 feet). Therefore, if either or both of these activities (underground coal <br />mining and/or coal bed methane drilling) were related to the soil contamination, it would be reasonable to <br />anticipate some change in the methane or oxygen concentrations measured in the soil methane monitors. The <br />data collected was reviewed for gas concentration changes over time. <br />Summary of data review <br />Data from the soil methane monitors was reviewed within the context of three distinct monitoring periods; <br />• Pre-coal bed methane well sealing (3199 to 912000) <br />• Post-coal bed methane sealing (and prior to mine flooding past 6758 feet) (10!2000 to 9!2001) <br />• Post mine flooding (10/2001 to 8/2002) <br />Readings were averaged over the three periods for each of the three measured gases, methane, oxygen, and <br />carbon dioxide. <br />All sites per period <br />Methane Oxygen CO2 <br />Mean -pre well seal 53.7 4.4 2.6 <br />Mean -post well seal 40.5 8.2 1.7 <br />Mean -post flooding 15.1 14.7 1.4 <br />A significant drop in the percentage of measured methane is noted using the averages during the three periods. <br />Also, a dramatic increase is evident in the measured oxygen content in the affected area. This increase in <br />oxygen may be due to atmospheric conditions now dominating the soil pore space following elimination of the <br />methane pressure gradient from below the soils. <br />Review of these data on an individual site basis indicates six monitors strongly suggest the sealing of the gas <br />wells was the main factor in the reduction of measured methane. (B2, B5, 69, B15, 622, 825) <br />