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1 <br />1 <br />The City of Everett <br />The Floyd & Snider Team Everett Landfill/Tire Fire Site <br />3.4.3.2 Frequency of Sampling <br />Off -site building sampling frequency will be quarterly (four times per year). Off -site building <br />monitoring will continue for three years unless there is a confirmed LFG detection, in which case <br />monitoring will extend for three years. Off -site monitoring will be discontinued after three years <br />if there is no confirmed LFG detection in any monitored off -site building. Off -site building <br />monitoring would be reinstated if perimeter gas monitoring confirmed migration of subsurface <br />gas at the Site boundary. In this case, monitoring of off -site buildings within 500 feet of the <br />affected probes would begin and continue until the probe reading became less than 5% <br />methane by volume. <br />3.4.3.3 Evaluation Methods <br />The monitoring technician will note and record the readings of the monitoring instrument. <br />Readings in excess of 100 ppm would be cause for further investigation and implementation of <br />contingency plans. <br />3.4.3.4 Reporting Requirements <br />The data from off -site building monitoring will be reported to Ecology on an annual basis. The <br />report will include the date of sampling, the locations sampled, and the results. <br />If a result exceeds 100 ppm the City will report to Ecology within 24 hours. The City will submit <br />a report to Ecology within 7 days of the initial exceedance. It will include the same information <br />as above, as well as actions taken and anticipated to correct the condition. <br />3.4.3.5 Contingency Plan Triggers <br />The Contingency Plan trigger concentration will be 100 ppm measured at any sampling location. <br />3.4.3.6 Contingency Plan <br />Verification monitoring will be initiated in response to an exceedance at any monitoring location. <br />If the exceedance is confirmed with repeated monitoring, sampling may be conducted to <br />determine whether the flammable gas originates from migrating LFG or from some other source <br />in the area such as the organic peat deposits or sanitary facilities. This would be done by <br />monitoring nearby perimeter compliance sampling locations and/or sampling and analyzing the <br />gas from the affected sampling location and comparing the results with an analysis of landfill <br />gas from the interior of the landfill. Fingerprint gasses could include freon 11, 12 and 113, vinyl <br />chloride, chloroethane, chlorobenzene, 1,4 dichlorobenzene, and 1,1 dichloroethene. Isotopic <br />identification, including tritium and carbon-14 could also be used. <br />If the presence of migrating LFG is confirmed, localized controls would be implemented. These <br />temporary controls would be evaluated, selected, and installed to control LFG in the vicinity of <br />the affected off -site building. These controls could include perimeter controls and/or localized <br />controls at the building site such as a vacuum extraction well. <br />Monitoring <br />P anNCM Everett 1-andfillwDF maker -final docslCompliance Compliance Monitoring and Contingency Plan <br />Monitoring Plan\CMCP 11-10.00.doc <br />FINAL - March 2001 Page 3-7 <br />