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Five VOCs were reported this quarter, all below the PQL (Table 1). Note that two compounds were previously regularly detected above the PQL. All VOCs detected in this well are among the VOCs found in MW-5 and MW-8, generally at lower concentrations. These data support the conclusion that MW-5 is closer to the source of the VOCs. Data is not sufficient to establish a trend in this well. Extent of Groundwater Impact Delineated The area of groundwater impact apparently extends northeast to a maximum distance of approximately 900 feet from the landfill property(Figure 5). The extent of groundwater impact is delineated based on the following evaluation of PCE concentration, as follows: • No PCE detected at MW-9A, and MW-10A. • The PCE concentration detected at MW-11A(0.15 ug/L) is slightly above the laboratory method detection limit of 0.13 ug/L • A linear extrapolation of the 1 ug/L contour interval lines between a PCE concentration of 5.4 ug/L at MW-5 and a PCE concentration of 0.15 ug/L at MW-11A The overall shape of the PCE plume is relatively symmetrical from an apparent source located near the northern boundary of the landfill, an area that includes both County and Caltrans refuse. The source location appears to be centered between well W-5, LFG probe GW-1, and well MW-8. The apparent western edge of VOC impacted groundwater adjacent to the landfill is the western edge of the Corcoran Clay Formation, (Figures 2 and 5). The apparent eastern edge of VOC impacted groundwater adjacent to the landfill is well SB-1,which is an apparent groundwater high elevation point in the shallow aquifer(Figure 2). The plume of impacted groundwater is elongated in the direction of groundwater flow, which is generally to the north- northeast from the landfill. After the first eight monitoring events and one climatic cycle,the data seems to indicate a decreasing plume in the area of well 10-A and 11-A. There does not appear to be trends in the VOC data for the other wells at this time. However,the concentration of VOCs MW-5 and MW-8 have been relatively stable since the installation of the LFG collection system in 2001, allowing the presumption that the plume has remained relatively constant during that time. Data from the off-site wells (MW-9A, MW-10A and MW-11 A)will indicate if the extent of the plume is changing. Deep Aquifer MW-6(Dower gradient): Concentrations of all the parameters analyzed were within established concentration limits this quarter (Table 2). Corral Hollow Sanitary Landfill 15 Department of Public Works/Solid Waste 1"Quarter 2014 Groundwater Monitoring County of San Joaquin—March 15,2014