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2-2_1 Monitoring Well Construction Development and Elevation Survey The three monitoring wells were drilled and installed by V&W Drilling, Inc (C-57 License #720904) The wells were installed in 8-inch diameter soil borings drilled by a truck-mounted drill ' rig equipped with hollow stem augers Each well casing consisted of 15 feet of two-inch diameter, Schedule 40, flush-threaded and machine-slotted (0 010-inch) polyvinyl chloride (PVC) well screen A five-foot section of blank PVC casing was threaded into the top of the well screen and extended to the surface In each well, a filter pack of#3 graded and washed silica sand was placed through the hollow stem augers as they were slowly retrieved and until the sand pack reached approximately one foot ' above the top of the screened interval Following the placement of the sand packs, the driller developed each of the wells by the surge and purge method Each of the wells was surged for approximately ten minutes using a wire-line surge block system Between surging cycles, approximately ten gallons of groundwater were bailed from each well Following well development, one foot of hydrated bentonite chips was placed within the annular space between ' the borehole and the well casing A surface seal of neat cement grout was placed over the hydrated bentonite The tops of the wells were secured with water-tight locking caps and 8-inch I0diameter, traffic-rated utility boxes During drilling, sod samples were collected at five-foot intervals using a modified California split- Ispoon sampler lined with 2-inch diameter by 6-inch long brass sleeves In the field, a geologist logged each of the soil samples for geologic and hydrogeologic characteristics and screened each sample for organic vapors using an organic vapor monitor, equipped with a PID The monitoring well logs including well construction diagrams and PID measurements are included as Appendix C Based on field observations, PID measurements and the distribution of existing sod ' sample data, no soil samples were submitted for laboratory analysis On November 5, 1998, Morrow Surveying (California Licensed Land Surveyor#5161) surveyed each of the newly installed wellheads Morrow Surveying located each of the wells and measured the elevation of the top of each well casings to the nearest 0 01 foot, referenced to the city of Tracy benchmark on top of the fire hydrant on East 110' Street (Elevation 5147 feet) The surveyor's report is included as Appendix D i7 1