ARCHIVED REPORTS_XR0007166 - Laserfiche WebLink

Home Browse Search

COMPLETION OF MONITOR WELL MW4 Monitor well MW4 was completed with 10 feet of machine slotted SCH 40 TriLock 2 inch diameter PVC screen (0 020) from 70 feet bgs to the total depth of the well at SO feet bgs The well was completed to surface with blank SCH 40 TriLock 2" diameter PVC The sand envelope consisted of 93 Monterey sand and was positioned from the base of the well to two feet above the top of the slotted casing The sand envelope was sealed on top with a 2 5-foot layer of hydrated bentonite pellets Cement (with less than 5% bentonite) was used to seal the annular space from the top of the bentonite seal to surface A locking thermos cap was used to seal the casing orifice A steel traffic box fitted with a locking system was set in concrete to protect the exposed well casing A construction diagram of the monitor well is included in Appendix D of this report DEVELOPMENT AND SURVEYING OF MONITOR WELL MW4 WEGE and Pittman Well Purging developed the new monitoi well on June 20, 2001 A two inch diameter-swabbing tool was used to agitate and condense the sand pack across the slotted casing intervals The wells were then purged with a truck mounted vacuum lift pump until solids were removed from the well casing and the ground water entering through the sand pack was no longer turbid Approlimately 50 gallons of water were purged from the 2-inch diameter well A licensed surveyor from Kjeldsen, Sinnock, and Neudeck, Inc suiveyed the elevation of top of the new well casing with respect to an existing benchmark on June 25 2001 The surveyor also resurveyed the elevations of the existing 3 monitor wells and provided i ectangular coordinates for all four wells The locations of the wells are shown in Figure 3 The elevations of the casing tops are included in Table 2 The re-survey of the existing monitor wells MW I, MW2, and MW3 showed them to be 0 66-0 67 feet lower in elevation than previously reported All three wells however, showed the same elevation decrease of 0 66 to 0 67 feet, indicating a change in the survey reference point rather than the monitoring wells The change in groundwater elevations at the wells, therefore, had no effect on past determinations of groundwater flow directions and gradients at the site COLLECTION AND ANALYSIS OF GROUNDWATER SAMPLES FROM l NN/4 A WEGE geologist collected groundwater samples from monitor well MW4 on July 25, 2001 Prior to sampling the well was purged of approximately 50 gallons of water using a Grundfoss submersible pump and dedicated poly tubing After purging, the well was allowed to recover to at least 80% of its original well volume A groundwater sample was then collected with a disposable polyethylene bailer and decanted with no head space into two 40 ml VOA vials containing 0 5 ml HCL acid as a preservative 5 Arc Pump QM 4-6, 2001