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GENESIS ENGINEERING&REDEVELOPMENT Ms. Amy Terrell August 21, 2006 Page 4 bottom. Ten-foot long well screens will be installed at an approximate depth interval of 30 feet to 40 feet below ground surface ("bgs"). The annular space around the well screen will be backfilled with clean, Monterey sand by placing the sand through the augers as they are removed from the boring. The well will then be surged to settle the sand pack prior to sealing the annular space. Additional sand will be added as needed to ensure the sand pack extends to at least 2 feet above the top of the well screen. At least 2 feet of hydrated bentonite will be placed above the sand pack. The remaining annular space will be sealed with cement grout. The wellhead will be completed below grade and will be protected by a traffic-rated monitoring well vault with a watertight lid. Deeper Monitoring Two monitoring wells will be installed to a depth no greater than 200 feet at locations shown on Figure 1 and Figure 3. These wells will be screened to target the depth intervals corresponding to the screened intervals of adjacent City of Ripon water supply wells. The corresponding depth intervals vary from 165 to 196 feet bgs. These wells will allow the groundwater chemistry to be determined in the deeper saturated interval in the immediate vicinity of the Site. To reduce the possibility of cross-contamination between the shallow and deeper aquifers, conductor casing will be installed into the aquitard above the proposed screened interval for the deeper monitoring wells. Based on a review and interpretation of lithologic information in the vicinity of the Site, the conductor casing will be set to an approximate depth of 145 feet bgs. The conductor casing will be installed using a truck-mounted drill rig equipped with cable-tool or mud rotary equipment. The monitoring wells will be installed through the conductor casing, using a truck-mounted drill rig equipped with hollow-stem augers. Continuous soil samples will be collected. The wells will be constructed of 4-inch diameter, schedule 80,poly_vinyl chloride casing,and machine slotted 0.010-inch screen at the bottom. Twenty-foot long well screens will be installed at the target intervals. The annular space around the well screen will be backfilled with clean, Monterey sancTby placing the sand through the augers as they are removed from the boring. The well will then be surged to settle the sand pack prior to sealing the annular space. Additional sand will be added as needed to ensure the sand pack extends to at least 2 feet above the top of the well screen. At least 2 feet of hydrated bentonite will be placed above the sand pack. The remaining annular space will be sealed with cement grout. The wellhead will be completed below grade and will be protected by a traffic-rated monitoring well vault with a watertight lid.