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Ei y surface downward to the 3-foot bentonite seal placed above the filter pack. A locking,water-tight well cover will be set in concrete to protect and secure the wellhead. Figure 9 depicts the monitoring well construction details in a schematic form. Following installation,the monitoring wells will be developed by surging and bailing to remove drilling residues and to produce low-turbidity groundwater in accordance with Appendix 6 procedures. Prior to sampling as described in Appendix 6,the proposed monitoring well(s) will be purged with a pre-cleaned bailer in order to remove stagnant water in the wells. During purging, key parameters including temperature, conductivity, and pH will be measured with a portable electronic meter and recorded. The purging will 4 continue until the monitored parameters stabilize (usually after 3 to 5 casing volumes of groundwater has been removed). Following purging, groundwater samples will be collected with pre-cleaned Teflon bailers and discharged with a non-aerating, bottom-emptying device into sterilized glass containers, capped with Teflon septa, labeled, and chilled in an ice chest for transport. Appendix 6 describes Groundwater Monitoring, Sampling, and Sample Management Procedures. The proposed monitoring wells will be surveyed relative to a permanent structure, such as a bench mark. Each wellhead will be surveyed from a designated point on the northern side of the top of the well casing, the groundwater level will be measured in the wells to an accuracy of +0.01 foot and tied to the California State Plane Coordinate System Zone 3 for this area as well as provide latitude and longitude coordinates for the well head. Vertical coordinates will be tied to the nearest vertical datum in use, most likely NAVD88 datum for this area. MainSDlEnvironmcmnlllSTE\Workplan\Workplanll[92007.wpd 20 . 1