SITE INFORMATION AND CORRESPONDENCE

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• The screen will be set across the intermediate zone,which will be identified from the soil cuttings retrieved during drilling. The intermediate zone is characterized as clayey silt to sand and gravel. The target depth interval for the screen is approximately 165 ft bgs to 175 ft bgs. • The bottom of the casing will be capped with approximately 5 feet of 2-inch Schedule 40 PVC blank casing to act as a sump. • The remaining length of the well casing will be constructed with 2-inch diameter Schedule 40 PVC blank casing. • Steel Centralizers will be set at approximately 177 ft bgs and approximately 100 ft bgs. • The filter pack will consist of Monterey No. 3 sand or an equivalent 8x20 sand. The filter pack will fill the annular space from the bottom of the borehole to 5 feet above the top of the screen. The filter pack will be gravity fed through a 1.5-inch diameter tremie pipe or pumped into the borehole. • The depth of the top of the filter pack will be measured continuously as it is added to the annular space. The depth of the top of the filter pack will also be compared to the estimated volume of filter pack needed to fill the annular space to that depth. • The screen of well MW-451 will be surged after the filter pack is placed to collapse any potential bridging of the filter pack during installation. • Five feet of fine mortar sand (#60 sand or equivalent 40x 100 sand) will be set as a transition sea] between the Monterey#3 filter pack and annular seal. The fine mortar sand will be gravity fed through a 1.5-inch diameter tremie pipe or pumped into the borehole. • Ten feet of medium bentonite chips or time release bentonite pellets will be set at the top of the transition sand. • One hundred twenty-five feet of a bentonite neat cement grout with 3% to 5% bentonite will be used to fill the annular space from the top of the time release bentonite pellets to approximately five feet below land surface. The bentonite neat cement grout will be pumped into the annulus through a 1.5-inch diameter tremie pipe. The tremie pipe will be installed within 5 feet of the desired seal depth and removed as the grout is installed. • A Class A Concrete surface seal will be pumped into the annulus from 5 ft bgs to land surface through a 1.5-inch diameter tremie pipe. • A 12-inch traffic rated flush-mounted well vault will be installed to protect and secure the well. 4.3.Borehole Construction for Well MW-402 • The borehole for MW-402 will be drilled by advancing a 7.785-inch O.D. mud rotary drill bit to approximately 80 feet below ground surface (ft bgs). • Drill cuttings will be examined on site by a geologist under the supervision of a California registered professional engineer to characterize lithology. Characterization will be conducted following the American Society for Testing& Materials (ASTM) standard D2488-09a, "Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). Work Plan—Installation of Monitor Wells 9672 SPX Corporation 3 Dudek Stockton,California May 2016