Laserfiche WebLink
® 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 on the test date. Testing previously <br /> attempted in April 1990 was unsuccessful due to the small vertical changes in <br /> water elevation that were achieved as the slug displaced water into the <br /> unsaturated filter pack. <br /> Based on the slug tests, hydraulic conductivities in the shallow wells appear to <br /> range from 2 x 10' 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 the slug & bail test results. This <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 /> Forward Landfill)TD 3-13 <br /> L:\Allied\2000.193\Reports\td:Sec-3.0:05/21/02 <br /> BRYAN A.STIRRAT S ASSOCIATES <br />