WORK PLANS - Laserfiche WebLink

Home Browse Search

OCTOBER 17,2005 NOA PROJECT NUMBER E05131A cleaned before leaving the site. Soil sampling tools will be cleaned with a non-phosphate detergent(e.g., Liqui-Nox) after each use. 2.4 Monitoring Well Installation All materials used during well construction will be new and will be kept in original packaging away from potential sources of contamination,until ready to be used. Monitoring Wells will be installed to a depth of 60 feet below ground surface. All monitoring wells will be constructed of 2-inch diameter, flush- thread PVC well casing with 20 feet of 10-slot well screen and 40 feet of solid surface casing. The base of the monitoring well will include a flush-thread solid end cap. The annulus between the monitoring well screen and borehole wall will be back-filled with#3 sand. The#3 sand will extend two feet above the screen interval. Prior to placement of the transition seal the sand pack will be surged with a surge block to ensure that the sand pack does not contained any bridged material. Once the sand is surged the sand pack will be measured to ensure that it remains two feet above the well screen. After the sanding is completed,the transition seal will be placed. The transition seal will consist of approximately three (3) feet of non-coated bentonite pellets. The bentonite will be hydrated prior to filling the remaining annulus with a cement-bentonite grout. The cement-bentonite grout will consist of a thoroughly mixed combination of seven (7) gallons of water for each 94 lbs. bag of Portland cement amended with three (3) pounds of bentonite powder. The grout shall be tremied in placed in order to avoid disturbing the hydrated bentonite seal. The combination of 2-inch diameter well casing and fl- inch nominal diameter well borehole will assure a minimum of a 2-inch annual seal between the well pipe and the well borehole. After placement of the grout column,a 2-foot diameter concrete surface seal will be installed,and will include a raised well head enclosure. A reference mark will be placed on top of each well casing. The well head on all wells will be secured with a water tight well head cap and a padlock. The Proposed monitoring well design is presented on Plate 11. The on-site geologist will create a well completion and boring log for each well. The log will document the as-built well construction features and the subsurface conditions encountered during drilling. 2.5 Monitoring Well Development No sooner than 48 hours after the monitoring well has been completed, the monitoring wells will be developed. Depending on well yield,wells will be developed using either a submersible pump for over pumping or using the surge and bail method. All well development water will be discharged to the ground surface. Well development activities will be conducted for at least one-hour at each well. Once the water table surrounding the wells has stabilized, the depth to groundwater will be gauged in each well using an electronic water level sounder calibrated to 0.01 feet. 2.6 Monitoring Well Survey A reference mark will be placed on top of each well casing, and the horizontal location and elevation of the reference mark and ground level will be determined by a Professional Licensed Land Survey. It 4