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The City of Everett <br />The Floyd & Snider Team Everett Landfill/Tire Fire Site <br />4.8.2 DEEP AQUIFER COMPLIANCE CRITERIA <br />If a COC concentration exceeds its cleanup level in the deep aquifer, the well will be re -sampled <br />within two weeks of laboratory confirmation and the sample tested for the analyte concentration. <br />If the exceedance does not re -occur, semi-annual monitoring will continue at the well. If an <br />exceedance occurs in the re -sample, quarterly monitoring will begin at the well to evaluate the <br />COC concentration. <br />If the COC concentration at that well does not exceed the cleanup level for 4 consecutive <br />quarters, or if the average value of the COC concentration does not exceed the cleanup level for <br />8 consecutive events, the COC concentration will be considered stable and semi-annual <br />sampling for the analyte at that well will resume. <br />The demonstration of deep aquifer well compliance will be determined after four quarters of data <br />collection. The statistical methodology selected after the Evaluation Monitoring period is <br />completed will be used to develop specific contingency plan triggers for the deep aquifer. If a <br />deep well is out of compliance based on evaluation of the four quarters of monitoring data, the <br />contingency plan shall be implemented. <br />4.9 CONTINGENCY PLAN <br />The contingency plan will evaluate the potential source for COC exceedance or increasing trend <br />in analyte concentration. These sources may include a change in the groundwater to surface <br />water pathway, migration of a slug of leachate from the landfill, or accidental modification of the <br />leachate collection system or landfill cover. <br />The site will be inspected, focusing on potential damage or modification to the leachate <br />collection system or cover. Based on the inspection, the leachate collection system may require <br />repair or upgrade. <br />The water quality and water elevation data set will be reviewed for changes in the site water <br />balance. Based on this review, a contingency investigation plan to assess potential sources for <br />the exceedances or increasing concentration trend will be prepared and submitted to Ecology <br />for review and approval. The contingency investigation may include additional or more frequent <br />water elevation or sampling at existing wells, or the installation and sampling of new wells. <br />Findings of the contingency investigation may lead to additional investigations to assess <br />contaminant sources and migration. <br />If shallow aquifer point of compliance criteria cannot be demonstrated, measures to prevent <br />shallow groundwater from flowing into surface water bodies will be implemented. These <br />measures could include increasing the pumping of leachate collection system to lower water <br />levels and ensure hydraulic flow into the leachate trench. <br />If pile installation results in a contingency trigger as described in 4.8.1 and 4.8.2, contingency <br />measures such as reducing the leachate head by extraction, additional pumping by the leachate <br />collection system, or decreasing water infiltration will be performed. <br />F: roects\C0B,BR Everett Landfill�PDF maker - final I <br />'� ' Compliance Monitoring and Contingency Plan <br />docslCompliance Monitoring Plan\CMCP 11-1aOO.doc p 9 g y <br />FINAL - March 2001 Page 4-12 <br />