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h'q KLEINFELDER B-3 GROUNDWATER WELL INSTALLATION 13-3 1 Monitoring Well Construction Construction details For shallow gioundwatei monitoring wells aie as follows • The well casing; are 2- of 4-inch inside diameter flush threaded point, schedule 40 PVC pipe • The wells ate constructed In 8- of 10-inch diametet boffin<gs • Well screen sections aic pertoiated with 0 010- of 0 020-inch factory-cut slots • The wells aie generally screened fiom 5 feet above to 15 feet below first groundwater The screen length is reduced if an aquitard NNith a minimum thickness of 5 feet is encounteied If an appaient aquitard is encountered, the well is usually terminated 1 to 2 feet into the aquitard Lffoit is made not to sc.teen across two aquifers If confined aquifer conditions or high vadose zone contamination aie encountered, the well screen is usually not set above the depth of first encountered groundwater Wells are usually not ' set in areas of suspected significant soil contamination • The PVC pipe and end caps aie steam cleaned prior to installation N� i4 backfilled with the The annt.ilai space between the screen and the all of the boring b appiopiiate clean sand to appioximately 2 feet above the top of the perforated sections Based on soil logs or a sieve test, modifications may be made regarding the size of sand to be used Installation of the sand may require that the sand be trernmied, using clean water • A 3- to 5-Foot bentonite plug is placed above the sand pack to provide a seal against surface water infiltration and to reduce the potential for cement grout to infiltrate into the water • The remaining annular space i,, tilled to the surface with cement/bentonite grout • The wells are ,ccuied in an abovegiound of undeigiound locking stovepipe The well heads may be enclosed in a water tight cement utility bo\ set flush to the ground surface when ' located in a tiatlic area ' 20-1108-24 E01/2019R]20 Page B-4 01999,Kleinteldcx Inc, February 5, 1999