Laserfiche WebLink
2 2 1 Monitoring Well Construction Development and Elevation Survey <br /> Mitchell Drilling installed MW-1 and MW-2 to total depths of approximately 9 25 feet bgs, and MW-3 <br /> to a total depth of approximately 35 feet bgs All three wells were constructed with 20 feet of two- <br /> inch diameter, Schedule 40, flush-threaded and machine-slotted (0 020-inch) PVC well screen <br /> Blank PVC casings were threaded into the tops of the well screens and extended to the surface <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 one to two feet above the tops of the <br />' screened intervals (i e , 4 feet bgs in MW-1 and MW-2, and 13 feet bgs in MW-3) The driller <br /> surged and purged the wells, following the placement of the sand packs and prior to the <br />' installation of the well seals Periodic surging and purging continued until the amount of <br /> suspended sediment in the groundwater decreased and stabilized and/or until at least five well <br /> volumes had been removed <br /> Overlying the sand packs, Mitchell Drilling placed two-foot layers of hydrated bentonite chips <br />' within the annular spaces between the boreholes and the well casings Over the hydrated <br /> bentonite, surface seals of neat cement grout were installed The tops of the wells were secured <br /> with water-tight caps and traffic-rated, flush-mount street boxes <br /> On August 15, 2002, Morrow Surveying (Land Surveyor License #5161) surveyed the newly- <br /> installed wellheads Morrow Surveying located the wells and other site features, and measured <br /> the elevations of the tops of the well casings to the nearest 0 01-foot, referenced to City of <br /> Stockton Benchmark#27 The surveyor's report is included as Appendix B <br /> 222 <br /> Soil Sampling and Anal sis <br /> During the drilling, undisturbed soil samples were collected at 5-foot intervals using a modified <br /> California split-spoon sampler lined with two-inch diameter by six-inch long brass or stainless steel <br />' sample sleeves A Ramage Environmental geologist logged each of the undisturbed soil samples <br /> for hydrogeologic and lithologic characteristics according to the Unified Soil Classification System <br />' and screenrd each sample for organic vapors using a photoionization detector (PID) <br /> 1 <br /> 8 <br />