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2 2 1 Monitoring Well Construction Development and Elevation Surve <br /> �t Mitchell Drilling installed all three wells in 8-inch diameter soil borings drilled to total depths of 30 <br /> feet bgs All three wells were constructed with 15 feet of two-inch diameter, Schedule 40, flush- <br /> threaded and machine-slotted (0 020-inch) polyvinyl chloride (PVC) well screen spanning from <br /> approximately 15 to 30 feet bgs Blank, two-inch diameter, PVC casings were threaded into the <br /> taps of the well screens and extended to the surface Due to the presence of heaving sands, the <br /> well string of MW-9 rose approximately 2 feet before the filter pack was installed <br /> Mitchell Drilling installed filter packs of Monterey#3 graded and washed sand within the annular <br /> spaces between the well screens and boreholes, and to approximately two feet above the tops of <br /> the screened intervals Prior to placing the bentonite seal, each of the wells was surged and <br /> purged for approximately 20 minutes to remove excess fines and settle the filter packs The filter <br /> packs were then tagged and additional sand was added, if needed Overlying the sand packs, <br /> Mitchell Drilling placed two-to three-foot layers of hydrated bentonite chips within the annular <br /> spaces Over the hydrated bentonite, surface seals of neat cement grout were installed The tops <br /> of the wells were secured with watertight caps and traffic-rated, flush-mounted street boxes set in <br /> concrete <br /> On April 26, 2005, Morrow Surveying, a state of California licensed land surveyor(#5161) surveyed <br /> the new and existing wells The surveyor measured the elevations of the tops of the well casings to <br /> the nearest 0 01 foot, referenced to the U S C & G S Benchmark#C-958 The surveyor's report is <br /> included as Appendix B <br /> 2 2 2 Soil Sampling and Analysis <br /> During drilling, undisturbed sal samples were collected at 5-foot intervals using a modified <br /> California split-spoon sampler lined with stainless steel sleeves A Ramage Environmental <br /> geologist logged all soil samples for hydrogeologic and lithologic characteristics according to the <br /> Unified Soil Classification System, and screened each sample for any organic vapors using a <br /> photoionization detector (PID) The monitoring well logs are included in Appendix C <br /> �I Based on the work plan scope and field observations, the sal samples collected at 15, 20, and 25 <br /> feet bgs from each well boring were submitted for laboratory analysis These samples were <br /> selected from the lower vadose zone, capillary fringe interval, and saturated soil <br /> 9 <br />