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The City of Everett The Floyd & Snider Team Everett Landfill/Tire Fire Site The new perimeter compliance sampling locations are shown in Figure 3-1. All of the new perimeter compliance sampling locations will be installed in vertical holes in the soil with perforated tubing in the zone to be sampled (a landfill gas probe). The depth will be to a point above the first groundwater surface. They will be installed in accordance with Chapter 173-160 WAC, Minimum Standards for Construction and Maintenance of Wells. 3.3.2 FREQUENCY OF SAMPLING Perimeter sampling frequency will be quarterly (four times per year). 3.3.3 EVALUATION METHODS Perimeter sampling evaluation will be by means of appropriate field monitoring instrument(s) capable of monitoring for methane in percent by volume of the lower explosive limit and in percent of total volume (the instrument is sensitive to 1 % or less explosive gas by volume). Readings will be recorded for methane, oxygen and carbon dioxide. Barometric pressure will be recorded the day of monitoring and for the previous day. Depth to water will be measured annually to confirm the location of the screen above groundwater. The results will be logged on field record forms for each sampling location. 3.3.4 REPORTING REQUIREMENTS The data from the perimeter compliance sampling location evaluation will be reported to Ecology on an annual basis. The report will include the date of sampling, the locations sampled, and the results. ' If a measurement exceeds the regulatory limit it will be reported to Ecology within 7 days. The report to Ecology will include the same information as above, as well as actions taken and anticipated to correct the gas migration. 3.3.5 CONTINGENCY PLAN TRIGGERS The contingency plan trigger concentration will be the lower explosive limit, 5% (50,000 ppm) by volume, measured at any perimeter compliance sampling location. 3.3.6 CONTINGENCY PLAN If methane is detected above 5% by volume in one or more probes, then those probes will be resampled within 72 hours. If methane is detected above 5% again, then a continuous reading methane sampling and recording device will be placed on one or more of the affected probes. Additionally, the City may collect canister samples for evaluation of gas constituents as discussed below. Continuous gas sampling results will be recorded for one month and the average of all recorded methane readings will be computed. If the average concentration of Everett Lan00.dfill\PDF docslCompliance maker -final Monitoring Compliance Monitoring and Contingency Plan Monitoring PIan1CMCP 11-10-OO.doc P an\CM FINAL - March 2001 Page 3-2