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El <br />4.4.2 Site Hydro geology <br />Ground water is found in site wells (G-1, G-2, W-1, W-2) at depths ranging from <br />124 to 156 feet (see Table 4-2). Ground water underlying the proposed landfill <br />site occurs under unconfined or partially confined conditions within gravelly or <br />silty sands. Static water levels in Wells G-1 and G-2 are higher than levels at <br />which ground water was first encountered during drilling, indicating some limited <br />confinement. Boring G-3 was not converted to a well due to (1) lack of readily <br />recognized water table above a depth of 170 feet (borehole dry overnight), <br />(2) borehole instability, and (3) use of a mud -rotary drilling system, which con- <br />cealed or temporarily sealed off water -bearing zones. <br />Depth to ground water beneath the base of the planned landfill ranges from 96 to <br />greater than 118 feet. Capillary rise was estimated for site soils using information <br />presented by Lohman (1972) on the relationship between rise and size of inter- <br />connected pores and openings in the soil. The silty sands (SM) overlying the <br />ground -water table in Well G-1 are expected to have a capillary rise of <br />42.8 centimeters. The silty sands and sandy silts (ML) overlying the ground -wa- <br />ter table in Well G-2 are expected to have a capillary rise of 105.5 centimeters <br />(Lohman, 1972). Capillary rise will not pose construction constraints at the pro- <br />posed landfill site since (1) the expected heights of capillary rise are less than <br />5 feet and (2) the minimum difference in depth between the proposed base of <br />landfill excavations and the ground -water table is greater than 90 feet. <br />Results of both in situ and laboratory permeability testing are summarized in <br />Table 4-3. Test results confirm the low permeability of generally fine-grained <br />sediments in the over 100 -foot -thick unsaturated zone. Permeabilities from tests <br />by EMCON range from 1 x 10-6 to 2 x 10-8 centimeters per second (cm/sec). <br />Similar values were obtained during previous site investigations by another con- <br />sultant. <br />Permeability of the saturated aquifer material was found to be 9 X 10-3 cm/sec at <br />depths of 130 to 160 feet. Appendix A (Section IV -B) includes an evaluation of <br />the test procedures and rationale used to obtain these permeability data. <br />PJ9 9390218&001..�' In <br />