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On November 6,2002,the County submitted an Evaluation Monitoring Plan which proposed methods to delineate the nature and extent of groundwater impact seen at MW-3. The Plan included drilling and sampling from temporary borings, and a step-out step-down approach if groundwater contamination was detected at those borings. On January 30, 2003,WDRs were issued by the California Regional Water Quality Control Board, Central Valley Region (CVRWQCB). These WDRs required the closure of Module"I" as corrective action because Module"I" is unlined and assumed to be the source of contamination. These WDRs also required the monitoring of soil gas for VOCs. In June 2003,the Evaluation Monitoring Program was completed. Groundwater samples from temporary borings were found free of contaminants. A soil gas well, SG-1,was bored to sample soil gas above the water table near groundwater monitoring well MW-3. Four VOCs were detected at SG-1; however,these compounds were not detected in the water samples taken at MW-3. Monitoring data from MW-3 continues to show no impact by VOCs. On September 16, 2003, due to delay in submitting the results of the Evaluation Monitoring Plan, the CVRWQCB issued a Water Code Section 13267 Order. This Order required that the County submit the results of the Evaluation Monitoring Program and an Engineering Feasibility Report that includes closure of Module `I'. On October 30, 2003,the County submitted a final Engineering Feasibility report to the CVRWQCB presenting the results of the Evaluation Monitoring Program. Corrective action was identified as preventing further ponding on the landfill surface near MW-3,this action taken in 1998. Further corrective action, including closure of Module"I",was not proposed due to the apparent success of previous corrective action, indicated by the of lack of groundwater contamination. On December 16, 2003, an Administrative Civil Liability Complaint was issued by the CVRWQCB for"not submitting a Closure Plan for Module `I"'. Negotiations in January 2004 resulted in a Clean Up and Abatement Order which requires the County to initiate the Foothill Landfill Site Improvement Project, which includes: • Final closure of the crest of Module "I" • Installation of a barrier between Module "I" and the future refuse placed over Module "I" in extension and completion of Module 1 • Landfill gas collection system • Partial Cover of those surfaces of Module "I"that are not covered by the inter-Module barrier or final closure • Two groundwater monitoring wells Foothill Sanitary Landfill 3 Department of Public Works/Solid Waste Isr Semester 2005 Groundwater Monitoring County of San Joaquin-July 29,2005