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0 9 Monitoring Well Installation Work Plan, Revislon 2 March 25, 2008 Page 3 of 5 A filter sand pack consisting of silica sand (grain size will be determined in the field) will be placed in the annular space between the casing and the borehole. The sand pack will extend from the bottom of the borehole to approximately two feet above the screened interval. A well seal consisting of approximately two feet of hydrated bentonite chips or bentonite pellets will be placed above the sand pack. The remainder of the borehole annulus will be filled with cement grout containing approximately 5 percent bentonite powder. The well will be finished at the ground surface within a monument set in concrete with a locking cap. Equipment Decontamination The drilling contractors will thoroughly decontaminate all down-hole equipment prior to initiating work. Where appropriate, the contractors will provide decontamination equipment apparatus for containing rinsate during decontamination and temporary storage of rinsate. Equipment decontamination activities will be performed in a designated area prepared to contain rinsate. Soil sampling equipment will be steam cleaned or washed in a dilute tri-sodium phosphate solution, rinsed with potable water, and final rinsed with distilled water between each sampling. Well Development Each monitoring well will be developed no less than 72 hours after completion. Well development will consist of removal of a minimum of 10 casing volumes of water and will continue until the groundwater extracted from the well is reasonably free of sediment. Development water will be contained in 55-gallon Department of Transportation (DOT) drums and stored onsite pending disposal. Well Survey After the subsurface construction activities have been concluded, a California licensed surveyor will survey the exact location and elevation of each of the new monitoring wells. Well Sampling and Gauging Each monitoring well will be sampled no less than 24 hours after well development. Initially, measurements of depth to water and total well depth will be obtained. If only two monitoring wells are installed, SGI will coordinate with the City to use one of their pumping wells as a third groundwater elevation gauging point in order to obtain the minimum data needed (three wells) to calculate groundwater gradient and flow direction. Using either water supply well 6 or 7, the City will shut down the pumping well and allow the water level to rebound and achieve stability. During the rebound period (which may take several days to a week), the City will take groundwater elevation measurements from the well and communicate the results to SGI. Once SGI determines The Source Group,Inc.