CORRESPONDENCE_1999-2002 - Laserfiche WebLink

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The Harney Lane Sanitary Landfill is located on Harney Lane approximately 7 miles east of Lodi, California(Figure 1). The site is a Class III landfill which stopped accepting waste in November 1991. A Migrant Farm Labor Camp is located adjacent to the landfill along the western boundary. The structures in the labor camp are occupied part of the year by farm workers. In accordance with closure regulations, a network of perimeter gas monitoring wells was installed by EMCON Associates in October 1991 (Figure 2). The wells are no more than 1000 feet apart and are spaced much closer than 1000 feet along the boundary with the labor camp to ensure detection of possible methane migration toward the structures. Each well contains three monitoring probes set at varying depths. The wells are monitored quarterly for methane. GAS PROBE MONITORING The County used a Landtec GEM 500 for the Fourth Quarter event on October 21, 1999. The GEM 500 was calibrated prior to monitoring by the Manufacturer. The probes are monitored in accordance with Waste Board protocol of purging one probe volume prior to taking a reading. The County has calculated the volume of gas that constitutes a probe volume for each probe. A time has been calculated for each probe using the manufacturers' pump rate information for the GEM 500. Once the time has been reached indicating that one probe volume has been purged, a reading is taken if the levels are constant. If the levels are changing at the end of the purge, a reading is not taken until the levels have stabilized. The landfill gas flare system has been operating continuously for approximately 3 years. The County is continuing its efforts to operate the gas control system to minimize the migration of landfill gas. Table 1 shows the gas monitoring results for the fourth quarter of 1999. 1