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e <br /> 8 <br /> s <br /> CONCLUSIONS <br /> The monitoring results show that methane concentrations exceed 5% in only a single probe <br /> this quarter. This probe is along the western side of the site located near the waste <br /> treatment ponds for the labor camp. The moisture from this winter has revealed that there <br /> are water blockages in the header pipes of the gas extraction system. The accumulation of <br /> water is due to some settlement of perimeter slopes and subsequent sagging of header <br /> pipes. During the previous quarter, these blockages effectively cut off pressure to the <br /> north half of the landfill. The County has been working to remediate this problem, and <br /> results from this quarter may reflect an increase in the effectiveness of the gas control <br /> system. The probes are monitored in accordance with Waste Board protocol of purging <br /> one probe volume prior to taking a reading. The County has calculated the volume of gas <br /> that constitutes a probe volume for each probe. A time has been calculated for each probe <br /> using the manufacturers' pump rate information for the GEM 500. Once the time has been <br /> reached indicating that one probe volume has been purged, a reading is taken if the levels <br /> are constant. If the levels are changing at the end of the purge, a reading is not taken until <br /> the levels have stabilized. <br /> Monitoring will continue with the next monitoring event in July 1999. Further monitoring <br /> will help determine if the results from this quarter reflect repairs made to the gas control <br /> system, and thus having a system that is working more efficiently. <br /> S:\WES\HL\GAS\2ndQU99G.wpd <br /> 4 <br />