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1 7hN3dwe11&Ro110 <br /> ' size slots using a peristaltic pump. The threaded PVC screen was inserted into the drive casing <br /> and down to the water-bearing zone. The drive casing was then pulled back 2 to 3 feet so that <br /> groundwater could enter the screen. <br /> 3.1.3 Backhoe Method <br /> ' A backhoe was used during this investigation to excavate shallow test pits to collect soil samples, <br /> assess shallow soil conditions, and investigate subsurface anomalies identified during the <br /> geophysical survey. Test pits were excavated to depths ranging from 5 feet to 10 feet bgs, and <br /> ranged from 5 feet to 30 feet in length. Soil samples were obtained from the backhoe's bucket <br /> and placed in 6-inch long stainless steel tubes. The tubes were covered with Teflon tape, capped, <br /> labeled, placed in an ice-cooled container, and delivered to the analytical laboratory using chain- <br /> of-custody procedures. Excavated soil was placed alongside the test pit area and placed back <br /> into the pits with the backhoe after sampling and logging the pits. Final compaction of the soil <br /> was not determined, nor was any attempt made to compact the soil to pre-excavation conditions. <br /> ' 3.1.4 Monitoring Well Installation <br /> All monitoring wells were constructed by installing clean, two-inch diameter flush jointed <br /> ' threaded schedule 40 PVC casing and factory-slotted screened sections with 0.01-inch <br /> perforations. Upon completion of the soil boring, the well casing was placed into the annular <br /> space within the augers and surrounded with a filter sand pack(No. 2/16). The augers were <br /> intermittently raised to facilitate the placement of the sand pack between the well casing and the <br /> sidewall of the boring. The sand pack was placed from the bottom of the boring to <br /> approximately two-feet above the slotted well casing. A two-foot thick bentonite pellet seal was <br /> placed above the sand pack and the remaining annular space was filled with a cement/bentonite <br /> ' grout. Wells were completed by setting a traffic-rated box or stand-up casing in a cement grout <br /> at the surface. Well construction details are shown graphically on the well logs. <br /> 1 25970119.DGD 13 December 1999 <br />