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Kennedy/Jenks Consultants samples difficult. The years 2006 and 2008 had a total of four sample events each; there were no sample events in 2007. Stormwater quality data are summarized in the WDRs (CRWQCB 2009). To assess the influence of the stormwater basin on groundwater quality, a water balance will be developed for the stormwater basin by estimating runoff from the facility based on measured rainfall amounts. Data collected during storms in 2009 and 2010 will be used to validate the P hydraulic calculations. Available water quality data will be used to estimate constituent loading l to groundwater. f 3.1.4 Onsite Sewage Disposal System ` Three groundwater monitoring wells (DWS-1 through DWS-3) are located near the existing domestic wastewater disposal area (mound system) (Figure 2). The wells were required by the San Joaquin County Environmental Health Department (SJCEHD), the agency responsible for oversight of the domestic wastewater system. Wells DWS-1 and DWS-2 are located adjacent to the mound where domestic wastewater is disposed. Although well DWS-1 is located upgradient of the mound, it may be within the hydraulic influence of the mound because the groundwater gradient is flat. Well DWS-3 is located downgradient of the mound. As part of the permitting process for the septic tank/mound distribution system installation, a nitrate loading study was (� prepared. Four shallow groundwater samples were collected from open boreholes and analyzed L for nitrate (as nitrate) concentrations. Analytical results were 53, 88, 140, and 170 mg/L (CRWQCB 2009). Because the samples were collected before domestic wastewater and/or winery wastewater discharges had begun at the facility, the source of the elevated nitrate concentrations was assumed to be related to previous land use. Kennedy/Jenks will review groundwater quality data from wells DWS-1, DWS-2, and DWS-3 C (Table 4) to assess the influence of the mound system. Depth to groundwater and nitrate and TDS concentrations will be measured during the next two quarterly monitoring events. Kennedy/Jenks will use the above information, as well as facility information on discharge flow to the sanitary mound system, to assess potential impacts from onsite sewage disposal. f 3.1.5 Old Process Water Ponds 4� Water was transferred out of Ponds A and B on 1 August 2009, and the ponds were demolished in September 2009. Because this potential source of variability has been removed, continued groundwater monitoring will serve to examine past effects and future improvements in groundwater quality. Potential impacts from the two former ponds will be evaluated using groundwater contour maps of water levels, nitrate, and TDS. The evaluation will focus on monitoring wells GW-7 and DWS-3, which are closest to the location of the former ponds. 3.1.6 Irrigation Canal Surface water features exist at the north and south property lines, and an abandoned irrigation canal historically bisected the property. The Woodbridge Irrigation District (WID) canal is located along the southern boundary of the facility, as shown on Figure 4. Four water samples were collected from the canal; the average FDS concentration was 50 mg/L (CRWQCB 2009). Leakage from this irrigation canal has the potential to impact groundwater quality and dilute Page 10 Hydrogeologic Investigation and Groundwater Sampling and Analysis Work Plan, Sutter Home Lodi Winery, Lodi, California g:Ys-gmuptadM jobWM865005.06 sueerho 09 woMWr to skl6hydm work plwMeAdm