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16 i SH KLEINFELDER File No. 20-3978-01.W 13 January 22, 1997 with a trisodium phosphate or non-phosphate detergent wash and rinsed with distilled water prior to collecting each soil sample. B-2.8 Soil Boring Closure and 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 wrapped in plastic or spread around the boring and left on site for disposal by the site owner. If requested, Kleinfelder can coordinate disposal of soil and water after analytical results are available. B-3 GROUNDWATER WELL INSTALLATION B-3.1 Monitoring Well Construction Construction details for shallow groundwater monitoring wells are as follows: • The well casing are 2- or 4-inch inside diameter, flush threaded joint, schedule 40 PVC pipe. • The wells are constructed in 8- or 10-inch diameter borings. • Well screen sections are perforated with 0.010- or 0.020-inch factory-cut slots. • The wells are generally screened from 5 feet above to 15 feet below first groundwater. The screen length is reduced if an aquitard with a minimum thickness of 5 feet is encountered. If an apparent aquitard is encountered, the well is usually terminated l to 2 feet into the aquitard. Effort is made not to screen across two aquifers. If confined aquifer conditions or high vadose zone contamination are 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 are steam cleaned prior to installation. The annular space between the screen and the wall of the boring is backfilled with the appropriate clean 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 sand may require that the sand be tremmied, using clean water. 20-3978-01,W131207PE030 Page 8-4 ©1997, Kleinfelder, Inc.