3800 RIVERFRONT BLVD 2025-07-23 - Laserfiche WebLink

1 The City of Everett The Floyd & Snider Team Everett Landfill/Tire Fire Site 4.4.1.3 Sampling Methods Monitoring wells will be purged and sampled using low -flow purging methods (Barcelona, 1994). Prior to sample collection, groundwater levels will be measured to the nearest 0.01-foot using a decontaminated electronic well probe. Following water level measurement, the wells will be purged by pumping a small volume of water in order to ensure sampled water represents aquifer conditions. The volume pumped will be determined in the field based on stabilization of field parameters: specific conductance, dissolved oxygen, and pH. Groundwater samples will be taken after water level measurement and well purging. 4.4.1.3 Sampling Parameters Groundwater sampling parameters will include volatile and semivolatile organic compounds, metals, PCBs, herbicides and pesticides, nitrate, nitrite, and chloride. A summary of specific compounds and analytical testing methodology will be included in the sampling and analysis plan, to be developed in accordance with the Scope of Work and Schedule, Exhibit D to the Consent Decree. 4.4.2 EVALUATION MONITORING SCHEDULE In general, at least ten sampling events will occur during the three-year Evaluation Monitoring period. Samples will be taken from groundwater monitoring wells identified for Evaluation Monitoring (see 4.4.1.1). The Evaluation Monitoring well network will be sampled quarterly for the first two years of Evaluation Monitoring. In the third year of Evaluation Monitoring, the ' network will be sampled semi-annually during periods of seasonal high and low groundwater levels. If analyte concentrations at a particular well show an increasing trend or seasonal fluctuation during the first two years of quarterly Evaluation Monitoring, sampling at that well will remain at a quarterly frequency during the third monitoring year. 4.4.3 REPORTING REQUIREMENTS For the first and second years of Evaluation Monitoring, results of groundwater level monitoring, laboratory data reports, and a summary of testing results will be described in quarterly reports submitted to Ecology. Each quarterly report will consist of copies of validated laboratory data, a summary table of the validated data, a table showing water level monitoring data, and a cover letter that describes the evaluation of the data. For year three, a single Evaluation Monitoring annual report will be prepared and submitted to Ecology. This report will describe the results of semiannual monitoring completed in year three and include all the data collected during the year. Additionally, the report will summarize the findings of Evaluation Monitoring and establish the rationale for future Performance Monitoring. The Evaluation Monitoring report will include: • A summary of Evaluation Monitoring results, with a comparison to cleanup levels and discussion of significant findings and conclusions, including a description of area background concentrations and resulting changes to cleanup levels. • Time versus concentration plots for each well, for each contaminant detected above the cleanup level during at least three sampling events. docs\jompliOceM Everett lndfiMCP maker - final Compliance Monitoring and Contingency Plan docslCompliance Monitoring PIan1CMCP 11-1D-1>D.doc FINAL - March 2001 Page 4-6