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URS Mr. Robert McClellon May 18, 2006 Page 2 After each boring has been advanced to the desired depth, a groundwater monitoring well will be constructed within the boring. We plan to install the screened interval portion of monitoring well from 5 feet above the static groundwater surface to 10 feet below the static groundwater surface. We expect that the groundwater monitoring wells will be screened from 13.5 feet to 28.5 feet bgs with 0.020 inch slot. The wells will be constructed with 2-inch polyvinyl chloride(PVC)pipe. The wells will be constructed by placing the PVC pipe at the desired depth. A filter pack(#3 Monterey sand or equivalent) will be placed between the well casing annulus and the boring wall to 1 foot above the top of the screened interval of the well. Two feet of bentonite will be placed in the annulus above the filter pack. The remainder of the annulus will be filled with neat cement. A christy box will be placed over the top of each well. The planned well completion details are shown on Figure 2. Soil cuttings will be placed on the ground surface at the site,because it is not expected that contamination will be encountered. However, if discolored soil or odorous soil is encountered during our activities, we will be prepared to place the soil in 55-gallon drums. Following the installation of the groundwater monitoring wells,the wells will be developed and sampled. Groundwater monitoring wells will be developed to remove fines from the geologic formation and the filter pack within the screened interval. A surge-and-bail method will be utilized. Borehole water will be gently surged back and forth with a bailer,through the well screen and filter pack to loosen fine-grained sediments. Bailing or pumping will be used to remove the dislodged material and accumulated fines from within the well. Wells will be developed until the water appears clear of fines, the well becomes dry and does not recover within two hours,or 10 casing volumes have been removed. Well development data(e.g., amount of water removed,pH, temperature,conductivity) will be recorded on a Monitor Well Development Data field form. Purged water will be placed in a 55-gallon drum. A licensed surveyor will survey the monitoring wells where the horizontal and vertical coordinates will be within 0.1 feet and 0.01 feet, respectively. A groundwater sample will be collected from each new groundwater monitoring well 24 hours after completion of well development. The procedures listed below will be followed when the groundwater samples are collected: • The water level will be measured from each monitoring well. The water level will be measured with an electronic water level sounder. For consistency, water level measurements will be taken from the top of the north side of the PVC well casing or at the surveyed reference mark. • Prior to groundwater sample collection,each well will be purged using a bailer,a peristaltic pump, or a submersible groundwater sampling pump with variable speed control. If the well is bailed or pumped dry during purging and the recharge volume is less than one casing volume after two hours, samples will be collected when a sufficient volume of water has recovered to allow completion of the sampling program. No further purging will be required. • For wells that are not purged dry during purging„ groundwater parameters (pH,temperature, and conductivity) will be recorded at least once every well casing volume while purging. Purging will continue until at least three casing volumes have been removed and the groundwater parameters have stabilized to within 10 percent,or until five well casing volumes have been removed. • Groundwater samples will be collected using a bailer or low-flow pump. During sample collection, care will be taken to ensure that bottles containing a preservative are not overfilled, to avoid diluting