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<br />1 <br /> <br />1 <br /> <br />II <br /> <br />1 <br />over time. As can be seen from the graph, the water <br />level measured at PZ P-1 has dropped very little in the <br />8-years of record. This is in contrast to the other two <br />piezometers which have at times indicated dry conditions. <br />Another interesting observation, which appears to have <br />become more pronounced in recent years, is the apparent <br />time difference between peaks and valleys in the plot of <br />PZ P-1 compared to the other two piezometers which appear <br />to move more or less together. These trends (in <br />conjunction with observed, surface seepage in the general <br />vicinity of PZ P-1) may be an indication that the area <br />surrounding PZ P-1 is continuously fed by some type of <br />well established aquifer or that the device is partially <br />plugged and is not functioning properly. The possibility <br />that the piezometer measurements do not reflect true pore <br />pressures is discussed in subsequent sections of this <br />report. At this point, without having performed <br />comprehensive field tests on PZ installations showing <br />questionable data, it must be, and is, assumed that all <br />of the available piezometer data is representative of <br />subsurface conditions rather than determined by the <br />methods of piezometer installation. Precipitation data <br />was also plotted on the first graph in an effort to <br />determine the sensitivity or lag effects precipitation <br />has on the measurements. This knowledge would be <br />valuable if it were found that heavy precipitation could, <br />within a short time frame, dramatically increase the <br />piezometric level within the pile and lead to <br />instability. No identifiable trends or specific <br />sensitivities to precipitation were discernable from this <br />effort, due in part to the coarse (quarterly) time <br />difference between PZ measurement data points. Even <br />though there were no small scale precipitation <br />correlations, a rough, general correlation can possibly <br />be inferred from the graph. <br />2.) The second and third graphs consider sections through the <br />southerly portion of the pile and include, only 1993 data <br />for PZs B2-4, B1-1 b BO-1 and B2-1, P-la ~ BO-1 <br />respectively. The plots of these piezometers indicate a <br />relatively constant piezometric surface. Piezometers <br />B2-1 & P-la show some response to precipitation. The <br />piezometric surface inferred from these plots can be <br />considered to follow a somewhat normal pattern, with a <br />source (the southerly toe or groin ditch) and an outfall <br />or pervious zone (underdrain No. 2). A disturbing point <br />is the fact that underdrain No. 1 is located between <br />these sections and does not appear to effect or draw the <br />piezometric surface down. The second and third graphs <br />are presented as Plates 4 and 5, respectively in the <br />Appendix. <br />6 <br />1 <br />