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selected in order to intercept the apparent aquifer measured by <br />existing wells P-1 and P1-T1 and to avoid puncturing existing <br />aquitards and creating possible vertical connections between <br />pervious layers via the existing well installations. Drilling <br />operations for hole No. 1 began on March 14, 1994. Hole No.l was <br />advanced to a final depth of 35-feet on the same day. Even though <br />three layers of moist to wet material were identified, the <br />suspected aquifer was not encountered. Because the suspected <br />aquifer was not intercepted, it was decided to abandon this hole, <br />move the Rig approximately 10-feet to the south and advance another <br />hole. Hole No. 1 was left open and periodically monitored until <br />April 8, 1994 at which time it was backfilled with bentonite "Hole <br />Plug" pellets. During the time the hole was open it indicated no <br />more than 4-feet of water in the bottom, which was likely the <br />result of precipitation and surface runoff. The absence of a <br />significant amount of water in this hole and the fact that the <br />suspected aquifer was not intercepted at this location indicates <br />that water bearing zones within the pile are not exclusively <br />comprised of horizontally bounded layers as would be expected, but <br />in some instances the zones must take the form of interconnected <br />pervious channels or conduits. This also explains why existing <br />well P1-T2 does not exhibit a piezometric surface similar to those <br />found in wells P-1 and P1-T1, even though they are located near <br />each other. <br />DRILL HOLE No. 2: <br />vole No. 2 was located approximately 10-feet south of hole No. <br />1 as noted above. Again the object of selecting this location was <br />to intercept the suspected aquifer measured by existing wells P-1 <br />and P1-T1. Hole No. 2 was started on March 14, 1994 and advanced <br />to a final depth of 60-feet on March 15, 1994. The suspected <br />aquifer was first encountered at a depth of 21-feet and the hole <br />was advanced to the target depth of the alluvium foundation <br />material plus 15-feet. During the drilling operation six apparent <br />moisture bearing zones were identified for installation of <br />piezometer wells. These six zones were separated by distinct dry <br />or less aervious zones varying in interval depth from 2 to 3-feet. <br />In addition to the six zones identified, piezometers were to be set <br />at the pile/alluvium contact (at 45-feet) and in the alluvium <br />foundation. After completion of the hole and determination of <br />piezometer tip target depths the hole was flushed with water to <br />remove drill cutting debris. The first piezometer tube was <br />slotted, installed and sanded. A thick bentonite slurry was <br />prepared and injected into the hole with a tremmie pipe to form the <br />first or bottom seal. During the slurry placement operation <br />problems were encountered in determining the depth or surface of <br />the slurry mixture as it was being injected. Thus, the length of <br />the bentonite plug exceeded the target depth for the next <br />piezometer tip. Instead of flushing the bentonite slurry out of <br />the hole and risk contaminating or sealing upper pervious zones it <br />was decided to abandon this hole and drill another approximately 3- <br />feet to the east. A more effective method for determining the <br />8 <br />