Laserfiche WebLink
K L E I N F F L D E R <br /> A-3 GROUNDWATER WELL INSTALLATION <br /> A-3.1 Monitoring Well Construction <br />' Construction details for shallow groundwater monitoring wells are as follows <br /> • The well casings are 2- or 4-inch inside diameter, flush threaded point, Schedule 40 PVC <br />' pipe <br /> • The wells are constructed in 8- or 10-inch diameter bonngs <br />' • Well screen sections areerforated with 0 010- or 0 020-inch factory-cut slots <br /> P ry <br />' • The wells are generally screened from 5 feet above to 15 feet below first groundwater <br /> The screen length is reduced if an aquitard with a minimum thickness of 5 feet is <br />' encountered If an apparent aquitard is encountered, the well is usually terminated 1 to 2 <br /> feet into the aquitard Effort is made not to screen across two aquifers If confined <br /> aquifer conditions or high vadose zone contamination are encountered, the well screen is <br />' usually not set above the depth of first encountered groundwater Wells are usually not <br /> set in areas of suspected significant soil contamination <br /> • The PVC pipe and end caps are steam cleaned pnor to installation <br /> • The annular space between the screen and the wall of the boring is backfilled with the <br />' appropriate clean sand to approximately 2 feet above the top of the perforated sections <br /> Based on soil logs or a sieve test, modifications may be made regarding the size of sand <br /> to be used Installation of the sand may require that the sand be tremmied, using clean <br />' water <br /> • A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal against <br /> surface water infiltration and to reduce the potential for cement grout to infiltrate into the <br /> well <br />' • The remaining annular space is filled to the surface with cement/bentonite grout <br /> • The wells are secured in an aboveground or underground locking stovepipe The well <br /> heads may be enclosed in a water tight cement utility box set flush to the ground surface <br /> when located in a traffic area <br /> 20-2322-05 E01/2011 8061 Page A-4 <br /> Copyright 2001,Kleinfelder,Inc January 12,2001 <br /> 1 <br />