ARCHIVED REPORTS_2006_20 - Laserfiche WebLink

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Ms. Christina Carbajal February 15, 2006 Page 3 to 53.8 percent by volume (see Table 1). During this reporting period, methane gas concentrations detected at Monitoring Probe Nos. GP-9, GP-11 and GP-12 have indicated a fluctuating trend in response to system adjustments. SCS will continue to monitor Probe Nos. GP-9, GP-11 and GP- 12 weekly as directed by the client. The next quarterly probe monitoring is due by the end of March 2006. Also, on January 5 and 12, 2006, SCS performed monthly monitoring of Temporary Gas Probes, defined as TGP-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 60.1 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). In addition, on January 12, 2006, SCS performed off-site bar hole punch testing on a fifty foot spacing along the property boundary adjacent to the temporary probes, as directed by the client. No methane gas was detected at any location tested during our monitoring and these results were submitted directly to the client. Finally, on January 23, 2006, SCS understands that Monitoring Probe No. GP-9 was relocated to the landfill perimeter and that the original Probe will be utilized for evaluation/testing purposes. On-Site Structure Monitoring In accordance with the approved testing schedule, the interior of the on-site structures are to be tested quarterly. The next quarterly interior structure monitoring is due by the end of March 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 in 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.