ARCHIVED REPORTS XR0001515 - Laserfiche WebLink

Home Browse Search

23 Monitoring Well Installations ' On September 26 and 28, 2001, under the supervision of Ramage Environmental, V&W Drilling, Inc (C-57 License#720904) installed four off-site groundwater table monitoring wells, to define the lateral extent of impacted groundwater and to expand the"groundwater monitoring capability at the site The locations of the four wells, designated MW-4, MW-5, MW-6 and MW-7, are shown ' on Figure 3 2 3 1 Monitorinq Well Construction Development and Elevation Surve ' V&W Drilling installed all four wells in 8-inch diameter soil s borings drilled to depths of 50 feet b g P g using a truck-mounted, hollow-stem auger drilling rig Each of the four wells consisted of 20 feet of two-inch diameter, Schedule 40, flush-threaded and machine-slotted (0 020-inch) polyvinyl chloride (PVC) well screen, spanning from approximately 30 to 50 feet bgs Blank PVC casings ' were threaded into the tops of the well screens and extended to the surface ' In each well, a filter pack of#2112 graded and washed silica sand was placed through the hollow stem augers as they were slowly retrieved and until the sand packs reached approximately two feet above the tops of the screened intervals Following the placement of the sand packs, the poll driller developed each of the wells by the surge and purge method Each of the wells was surged for approximately 5 minutes using a wire-line surge block system Between surging cycles, approximately 5 gallons of groundwater were bailed from each well Following well development, two feet of hydrated bentonite chips were placed within the annular spaces between the boreholes and the well casings Surface seals of 20 1 cement bentonite neat grout were placed over the hydrated bentonite, under PHSIEHD observation The tops of the wells were secured with water- tight locking caps and 8-inch diameter, traffic-rated utility boxes iDuring October 2001, Morrow Surveying (California Licensed Land Surveyor#5161) surveyed the newly-installed wellheads, and re-surveyed the three existing monitoring wells Morrow Surveying ' located the wells and measured the elevations of the tops of the well casings to the nearest 0 01 foot, referenced to City of Stockton Benchmark#183 The benchmark is a brass disc in a ' monument box at the intersection of the west side of Airport Way and the centerline of Charter - Way (Elevation 17 132 feet above mean sea level) The surveyor's report is included as Appendix C . 10 1