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• Spatial representation of the existing Forward Landfill site (horizontal)—one <br /> shallow well on the southern side and two shallow wells on the northeastern <br /> side of the landfill were tested. <br /> • Spatial representation of the upper aquifer (vertical)—one deep well, MW-10, <br /> was tested for comparison with the three shallow wells. <br /> ® Sufficient submergence of the well filter pack to allow the greatest possible <br /> vertical displacement of water during slug insertion/withdrawal. The four <br /> wells chosen were sufficiently deep that the filter pack around and above the <br /> perforated section was submerged,owthe>test-1date. Testing previously <br /> attempted in April 1990 was unsuccessful due to the small vertical changes in <br /> water elevation that were achieved as the-Aug displacje4water initolhe <br /> unsaturated filter pack. <br /> Based on the slug tests, hydraulic ductivities e�hallowv cells appear to <br /> range from 2 x 10.2 to 2 x 10-3 cm/sec (57 to 5.7 feet per day[ft/d]). These results <br /> are consistent with estimates for hydraulic conductivities of sandy silts and very <br /> fine to fine sands. The calculated hydraulic conductivities are summarized on <br /> Table 7. <br /> Aquifer pumping tests completed by Camp Dresser McKee Inc. (1999) and <br /> groundwater modeling that was completed for the existing Austin Road Landfill by <br /> Herst& Associates/ Andrews Environmental Engineering ([HA/AEE], 2001) <br /> indicate that the hydraulic conductivity of upper aquifer materials in the area is <br /> significantly higher (250 ft/d) than was.measured in.1he slug & bail test,sesults.._ his <br /> higher value is consistent with values listed in the literature (Driscoll, 1986) for <br /> medium-to coarse-grained sands and appears to most closely approximate the <br /> types of materials encountered within water-bearing zones in monitoring wells-at <br /> the site. <br /> Using the hydraulic conductivity value selected by HA/AEE (250 ft/d), an average <br /> groundwater gradient of 0.003 percent, and an estimated effective porosity of <br /> 0.25, the calculated average linear groundwater velocity at the site is: <br /> v = [(K)(h/I)]/n = [(250 ft/d) (0.003)] / 0.25 = 3 ft/d <br /> Where: v = velocity (cm/sec) <br /> K = hydraulic conductivity (cm/sec) <br /> Forward Landfill JTD 3-13 <br /> L:\Allied\2000.193\Reports\fiinaljtd:Sec-3.0:08/20/01 <br /> ®RYAN A.STIRRAT&ASSOCIATES <br />