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05/23/95 14:35 '&801 272 0430 IIONTGONERY WATSN 1J003 location of sample interval in respect to 5nal depth to represent soil properties of the proposed gallery. Once total depth of the borehole is reached,bentonite will be tremied through the inside of the auger up to a depth of 26 feet. A 20-foot section of 2-inch slotted casing(0.02-inch slot)threaded to a 5-tiwt section of blank casing will be suspended through the center of the auger from the ground surface. Monterey 12 x 20 mesh filter pack will then be slowly treaded through the auger when the augers are removed to ensure proper placement of the filter pack up to a depth of 4 feet. A 2-foot bentonite seal will be placed on top of the filter pack. The bentonite seal will be partially hydrated by adding at least l0 gallons of clean potable water. A temporary flush-mounted traffic-rated well vault will be installed over the well_ The top of the infiltration test well will be secured with a watertight well cap. • Both constant-head and falling-head field infiltration tests will be performed in each infiltration test well to estimate a combination of vertical and horizontal_hydraulic conductivity of the strata intersected by the borehole. Potable water wilt be frequently added to the infiltration test well for at least 12 hours before the infiltration tests to create saturated conditions in the surrounding vadose zone prior to each falling-head test. • The falling-head test will be conducted by 5lfing the infiltration test well to an elevation near or at ground surface. The water level.within the test well then will be measured at regular intervals by atransducer and confirmed with manual measurements until the water level has dropped below the bottom of the casing. The process will be repeated as deemed practical in the field. The constant-head test will be performed subsequently after the falling-head test by pumping potable water into the infiltration rest well and adjusting the now until a constant water level is obtained. The equilibrium flow rate and manual water level measurements will be recorded on infiltration test data sheets and the field notebook: • The following tests will be performed on select soil samples collected from each boring: Visual classification(ASTM D2487)-for split-spoon samples collected in the eight 40-foot boreholes Grain-size sieve and pipette analyses (EPA Method 2-from USGS Procedures)-40 tests to characterize soil (to test one unsaturated, one capillary fringe,and one saturated sample from each borehole) In-situ moisture/density(ASTM D698)-40 tests to characterize soil (to test one unsaturated, one capillary fringe,and one saturated sample from each borehole) Specific gravity(ASTM D 854)-8 tests to characterize soil(to test coarse-grained material of Upper Horizon in eight boles to be selected in the field)