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5.10.1 Ground -Water Monitoring The proposed ground -water monitoring system described in the Ground -Water Monitoring Plan, North County Sanitary Landfill, San Joaquin County, California, EMCON Associates, March 1988, focuses on the two initial fill modules. These modules have a service life of approximately 6 years. The system incorporates the two existing ground -water monitoring wells (G-1 and G-2), in addition to one new well (G-3). The location of the new well is approximate; it may be necessary to change the location slightly to conform with construction or operation activities. The well locations were selected to provide a sufficient number and coverage of wells to yield ground -water samples that represent both background water qual- ity, as well as the water quality passing beneath the site. As the ground -water contour map in Figure 4-10 shows, ground water in the site vicinity is mounded, with local flow directions potentially different than the south- west gradient observed regionally. The gradient is influenced by pumpage from nearby domestic and irrigation wells. Water -level measurements from the initial three landfill monitoring wells and the domestic on-site well will provide data over the next few years regarding fluctuations in flow directions. Wells G-1, G-2, and G-3 should be operational before initiating waste disposal at the facility. Other wells will be added as filling progresses across the site. To establish baseline ground -water quality data for the site, EMCON analyzed ground -water samples from Wells G-1, G-2, and G-3 for the following parame- ters: • Volatile organic compounds, according to EPA Method 624 • Semivolatile organic compounds, according to EPA Method 625 • Pesticides and polychlorinated biphenyls, according to EPA Method 608 PJ9 9390218A.00W 59 • Total organic carbon • Chloride • Iron