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k` ■ KLEINFELDER A-2.7 Soil Boring Closure and Soil Cutting Disposal Soil borings are closed immediately after the collection and logging of soil samples. Closure is '! accomplished by grouting the boring with a cement/bentonite slurry or as otherwise required. Drill cuttings will be placed in 55-gallon drums or wrapped in plastic and left on site for disposal ` by the site owner. If requested, Kleinfelder can coordinate disposal of soil and water with contractors after chemical analysis results are available. A-3 GROUNDWATER MONITORING A-3.1 Monitoring Well Construction Construction details for shallow ground water monitoring wells are as follows: • The well casing will be 2-inch inside diameter, flush threaded joint, schedule 40 PVC pipe. • The wells will be constructed in 8-inch diameter boreholes. • Well screen sections are perforated with 0.010- or .020-inch factory-cut slots. This parameter is assessed (and modified if required) after the boring logs and, if warranted, a sieve test has been performed and the results received. • The wells are generally screened from 5 feet above to 20 feet below first groundwater. The screen length is reduced if an aquitard with a minimum thickness of 5 feet is encountered. If ` an aquitard is encountered the well is usually terminated 1 to 2 feet into the aquitard. Effort is made not to screen across two aquifers. If confined aquifer conditions or high vadose zone contamination is encountered, the well screen is usually not set above the depth of first encountered ground water. Wells are usually not set in areas of suspected significant soil contamination. .. • The PVC pipe and end caps are steam-cleaned prior to installation. • The annular space between the screen and the wall of the boring is backfilled with the appropriate clean Lone Star Industries 0/30 or 2/12 Monterey sand to approximately 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 0/30 sand may require that the sand be tremmied, using clean water. In this event, a sample of the tremie water is collected, unless the source is known to be clean. • A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal against surface water infiltration. r. 21073/ST03R1067 Page A-3 O 2003 Kleinfelder,Inc. July 28,2003 r