RES 86453 - Laserfiche WebLink

Mr. Martin W. Inderbitzen May 27, 1986 Page 4 Drilling Program We developed a systematic drilling program for selecting borehole locations that allowed us to define the extent of the LFG migration onto the Martin Property. Figure 1 shows the borehole locations and the gas concentrations measured in those boreholes. The boreholes labeled with "M" and "B4R" were drilled during this contract work. All others were drilled during previous studies. Figure 2 shows the six drilling steps used to define the LFG migration pattern and boundary. In 1985 a methane concentration of 5 percent was measured in B4. Gas concentrations were 1 percent or less in all other boreholes drilled during that study. Therefore, the field investigation started at B4. A threshold methane concentration of 1 percent was set as an indicator for drilling additional boreholes. Gas concentrations of 1 percent indicate a migration boundary, and no more boreholes were drilled in that direction. Gas concentrations of 1 percent or greater indicate a need to drill farther out onto the property. The actual process used to select borehole locations is summarized below. The six steps listed below correspond to those shown on Figure 2. Step 1. Drilled borehole, M1, about 150 feet from the property line. Measured a methane concentration of less than 1 percent. This indicated a boundary on the areal movement of gas. Step. 2. Moved back toward B4 and drilled boreholes, M2, M3, and M4 in an arc with a radius of about 75 feet from B4 to check the direction lateral migration. Measured methane concentrations of less than 1 percent in M2, but greater than 1 percent in M3 and greater than 5 percent in M4. This indicated that we had not found the migration boundary along the line between B4 and M3 or between B4 and M4. Step 3. Drilled M5 and M6 about 75 feet out from M3 and M4. Measured methane concentrations of less than 1 percent in M6 and greater than 5 percent in M5. This indicated that we had found the migration boundary at the end of a line from B4 through M3 and M6, but not along the line from B4 through M4 and M5. Step 4. Used M5 as the new "hub" and drilled two boreholes, M8 and Mg, from 100 feet to 125 feet out from M5. Measured maxima methane concentrations of 2.7 percent in M8 and 0 percent in M9. This indicated that although the methane concentration was greater than 1 percent in MS, it was greatly reduced compared to that measured in M5. Subsequently, only trace levels of methane have been identified in probe MS. BROWN AND CALDWELL PO 8OX8045 WALNUTCREEK, CA94596-1220 · (415)937.9010 TELEX33-6490, OFFICE AT348OBUSKIRKAVENUE PLEASANTHILL94523