ARCHIVED REPORTS_2006_21 - Laserfiche WebLink

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Ms. Christina.Carbajal July 19,2006 Page 3 Also,on June 14, 19, and 29, 2006, SCS performed testing of subsurface evaluation monitoring point ETGP-09 as requested by the Client(see Table 5). These test results are intended for evaluation purposes to assist in LFG extraction well adjustments. Finally,on June 1.4,2006, SCS performed monthly monitoring of Temporary Gas Probes, defined as TCrP-01. through TGP-39, as directed by the Client. Results of this monitoring indicated that methane gas concentrations in excess of the LEL were detected at several locations tested(up to 58.4 percent by volume). However, during their reporting period,SCS has continued to observe a fluctuating trend in the detected methane gas concentration.Note,that these probes are intended for evaluation purposes only and are not compliance locations(see Table 1). On-Site Structure Monitorin In,accordance with,the approved testing schedule,the interior of the on-site structures are to be tested quarterly. On June 6, 2006, SCS performed the required testing and included these results in our second quarter 2006 probe and structure monitoring report. The next quarterly interior structure monito '. is due by the end of September 2006. LFG Extraction Well Testing System.adjustments are required whenever an extraction well exhibits an,unacceptable change in methane and/or oxygen gas concentration (which could be due to an overpull or underpull condition). Overpull occurs when the extraction rate of a particular extraction well exceeds that of the LFG generation rate within the radius of influence of the well. ]During this overpull condition,, air can be drawn through the ground surface to the extraction well and then ultimately be injected into the flare. if an excessive overpull condition is allowed to continue for a long period,a significant drop it).the methane gas content of the LFG and/or a subsurface landfill fire could occur. Underpull occurs when the extraction rate of a particular extraction well is less than the generation rate within the radius of influence of the well. This condition,could result in off-site subsurface LFG migration and/or surface emissions. Results of monthly testing of LFG extraction wells performed on June 6, 19 and 29,2006 (see '.fable 2) indicate that several. extraction wells exhibited an overpull and/or underpull. condition. These conditions are necessary to maintain operational criteria(e.g.maintain am.inimum 1400 degrees Fahrenheit flare exit gas temperature)at the BFS and to help maintain/decrease methane gas concentrations at perimeter monitoring probes to below the LEL. SCS will continue to monitor and adjust all LFG extraction wells to minimize the amount of overpulI while maintaining operational criteria.