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COMPLIANCE RECORD Enclosed you will find correspondence between the County and the Regional Board regarding t compliance issues related to groundwater and surface water sampling,reporting, and monitoring. The County has submitted an Evaluation Monitoring Plan to delineate the nature and extent of the suspected release affecting groundwater in the vicinity of MW-3. The first step of the evalution (field investigation) is scheduled to begin in April 2003. The County has procured a contractor to perform the field investigation. he two compo Trichloroethene and 1 1-Dichloroethene It should be noted that t p ( )which initially indicated impact to groundwater at MW-3 are consistently"non-detect." TCE has not been detected in four consecutive quarters, since November 2001. 1,1-DCE has not been detected in six consecutive quarters, since April 2001. rThe lack of consistent detections can be an indication that VOCs are no longer being transported through the unsaturated zone to groundwater. The proposed Evaluation Monitoring Program to delineate the nature and extent of the suspected plume will assist in determining if a release from the landfill is still present. The new groundwater well (MW-2R)is also scheduled for installation in May 2003. This new well will replace MW-2,which is located on the footprint of Module 1. MW-2 will be abandoned at the same time MW-2R is installed. MONITORING SUMMARY Groundwater General Water Quality Parameters An evaluation of the 2002 groundwater monitoring data shows that all constituents were within ' interwell tolerance limits except for Chloride in MW-3. The concentration of Chloride in groundwater samples collected from MW-3 exceeded the established concentration limit in both the third and fourth quarter. Statistical analysis indicates that there is an increasing trend in concentrations of Chloride and Sulfate and a decreasing trend in the pH value of groundwater from MW-3. ' A statistically significant increasing trend was also noted in Chloride for MW-2. However, a time series plot of the historical data(see Appendix F) shows the concentrations in MW-2 follow ' those in MW-1 (upgradient) very closely. The means of the historical data in MW-1 and MW-2 are separated by only 0.1 mg/L. ' VOCs Foothill Sanitary Landfill Department of Public Works/Solid Waste 4'"Quarter and Annual 2002 Groundwater Monitoring Report H- 1 County of San Joaquin