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• KLEINFELDER Following completion of the drilling, a 2-inch diameter PVC monitoring well will be installed in the boring. The soil boring will be advanced approximately 10 feet into groundwater. The monitoring well will be constructed with schedule 40 PVC and a 15 foot long .010- inch screened section. The screened section will be placed approximately 10-feet below and 5-feet above first encountered groundwater. The screened section will be surrounded by and covered by clean sand filter pack (#2/16). A 3 to 5 foot bentonite transition seal will be install above the filter pack. The bentonite will be hydrated with potable water. The remaining annular space above the bentonite seal will be sealed using a neat cement grout mixture with bentonite powder added to retard the heat of hydration, to limit the chance of damaging the casing. See Plate 3 for a typical monitoring well construction diagram. 4.3 MONITORING WELL DEVELOPMENT AND SAMPLING A minimum of 48 hours after installation, monitoring well MW-4r will be developed to remove fine silt from the well bore and to effectively increase the hydraulic radius of each monitoring well. Surging along the screened interval of the well will be performed to draw the sediment from the formation into the filter pack and the well and to set the sand pack. The monitoring well will be developed as described in Appendix A.3.2. In addition to developing the monitoring well until the discharge runs relatively clear of fines, the discharge will be periodically monitored for pH, temperature, and specific conductance to record stable groundwater parameters during the development task. The newly installed monitoring well will be added to the monitoring well network. Sampling will be conducted in accordance with the existing quarterly sampling schedule for the site. Water level measurements will be conducted prior to purging and sampling the wells. The depth to groundwater will then be measured in each well according to the protocol described in Appendix A-4.1. Approximately three to five well volumes will be purged and samples will be collected as described in Appendix A-4.2. Each of the water samples collected for quantitative analyses will be submitted under chain-of-custody control to a State of California-certified laboratory for the requested analyses. The new monitoring well will be surveyed for elevation and location to establish the groundwater gradient using the established datum as a reference point. 34091.E01/ST05R040/JZ:ly Page 5 of 9 0 2005,Kleinfelder,Inc. January 13,2005