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Escalon Cellars TL F06601.01 <br /> February 9, 2000 Page 4 <br /> matter in the effluent or in the sumps, chloroform and or other trihalomethanes can be formed. No <br /> trihalomethanes or methylene chloride have been detected in water samples collected from the <br /> winery production wells. Methylene chloride sporadically detected in water samples collected from <br /> the sumps is most likely a result of laboratory contamination of the samples as methylene chloride <br /> is a common laboratory contaminant. <br /> 4.0 PROPOSED TASKS <br /> Twining proposes the following tasks to determine whether ground water has been impacted by <br /> Freon 11 and/or trihalomethanes. These tasks include monitoring the existing production wells at <br /> the winery and the installation of three monitor well near the disposal fields and one background <br /> monitor well. Each of these tasks are detailed below. <br /> 4.1 Task 1 Sample active Canandaigua production wells Nos.3 and 4 quarterly for VOC's <br /> and trihalomethanes - Twining proposes to sample production wells No. 3 and 4 <br /> quarterly for a period on one year to determine whether Freon 11 is present in the <br /> ground water in the vicinity of the winery. The last two sampling events have not <br /> detected Freon 11 above the method detection limits. If Freon 11 is detected <br /> consistently at significant levels, Canandaigua will prepare an additional work plan <br /> to determine its source and extent. <br /> Ground-water samples will be collected using the permanent pumps in wells 3 and <br /> 4. Each well will be allowed to run a minimum of 20 minutes prior to sampling. <br /> Electrical conductivity and pH will be measured and the pumps will be allowed to <br /> run until these parameters stabilize. Water samples will be collected in laboratory <br /> prepared sample bottles, stored in an ice chest at 4° C, and delivered to Twining <br /> Laboratories until chain of custody. The samples will analyzed for purgeable <br /> halocarbons using EPA method 601. <br /> 4.2 Task 2 Monitor Well Installation-Twining proposes to install four monitor wells to assess <br /> the ground-water flow direction beneath the site, to determine background water <br /> quality and to find out whether water applied to the disposal field has impacted the <br /> shallow ground water with Freon 11 or trihalomethanes. One of the monitor wells <br /> will be located in the southeast portion of the plant to determine background water <br /> quality. The well should be upgradient of the winery, based on regional water <br /> elevation maps prepared by San Joaquin County. Four additional monitor wells will <br /> be placed adjacent to the disposal fields. The proposed locations of the monitor <br /> wells are shown are Drawing 2. <br /> 4.21 Monitor Well Installation Procedures -The monitor wells will be drilled using the hollow <br /> stem method of drilling. The wells will be drilled, logged and installed using Twining's standard <br /> procedures which are in Appendix A. Twining proposes to install 30 feet of perforations in each <br />