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1 <br />~l <br /> <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br /> <br />t <br />1 <br />1 <br /> <br />1 <br />1 <br />1 <br />because pressures measured only include known water bearing zene~. <br />P. sigr:ificant portion of the material in the pile is sufficiently <br />impervious that it has not yet been affected by the seepage <br />pressures. For example, it has been noted previously that the <br />horizontal extent of some water bearing channels is likely to be c.. <br />the order of 20 to 30-feet wide as evidenced by conditions <br />encountered in the area of piezometer well P-1. Thus, certain zones <br />within the pile may not contain the specific moisture bearing <br />channels being measured. Because the actual horizontal extent of <br />such channels are unknown, the pore pressures are modelled ignoring <br />the channelization effects assuming that each distinct zone is <br />hydraulically homogeneous. This assumption adds conservatism to <br />the pore pressure model. <br />SECTION A-A: <br />As noted previously section A-A represents piezometric <br />conditions measured in the 200 and 400 series piezometers. <br />piezometric level plots for the 200 and 400 series piezometers are <br />presented as Plates 30 and 31 respectively of the Appendix. I. <br />general the piezometric levels measured through section A-A have <br />remained constant during the 18-day monitoring period. Initial <br />conditions in piezometers 401, 402 and 403 indicated that some type <br />of impervious boundary existed at an elevation of 4879.25 (bottom <br />plug elevation of PZ 403) as all three of these piezometers <br />indicated a piezometric water surface at elevation 4908 +/-. This <br />condition changed over the weekend of April 9 5 10, 1994. This <br />data was originally interpreted as indicating that the measurements <br />which previously suggested a connection between the measured zones <br />and a pore pressure system controlled by a horizontal boundary <br />actually were anomalies. After this adjustment, each of the three <br />piezometers appeared to measure pore pressures in unconnected zones <br />within the pile. These conditions were evident until the last fire <br />days of the monitoring period when piezometers 402 and 403 began to <br />indicate a separate, yet somewhat parallel increasing tre^.d in <br />their respective piezometric surfaces. The original and present <br />trend of piezometer 402 & 403 measurements, as well as the <br />pronounced surface seepage seen just above the first slope bench <br />(elevation 4873 +/-), aga_n strongly indicate that a horizontal <br />boundary or network of pervious conduits exists within the pile at <br />elevation 4879 +/-. <br />In order to develop a stability model for critical sectic:. <br />A-A, the maximum observed pore pressures within the pile and <br />foundation alluvium were sought. The determination o` pore <br />pressures were made by calculating the pressures measured above <br />each of the individua'_ piezometer's sand packed zone. A graahic <br />comparison of maximum and minimum pore pressures measured at <br />section A-A during the monitoring period is presented on Plate 3~ <br />of the Appendix. The following tables present pare pressures <br />measured on the final day of piezometer monitoring: <br />lg <br />