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<br /> <br /> <br />1 <br />1 <br /> <br />1 <br />1 <br />1 <br />1 <br /> <br />1 <br />1 <br /> <br />1 <br /> <br /> <br />1 <br />analysis. There is, however, a question regarding the strength <br />value of the alluvium foundation material, which was apparently <br />assumed, in the "Stability Evaluation". Specific questions <br />regarding material strength are addressed in subsequent sections of <br />this report. <br />In order to analyze present stability conditions the results <br />of 156 field density test results from CRDA No. 1 were tabulated to <br />determine the average in-place wet density of the refuse material. <br />A 7.5$ increase in unit weight is realized when comparing the wet <br />density of 92 pcf, used in the original design analysis, with the <br />average in-place wet density of 99.47 pcf determined from the field <br />density results. Thus, the higher value is incorporated in the <br />present stability analyses. The following table summarizes the <br />results of the in-place density evaluation: <br />CRDA No. 1 IN-PLACE DENSITY SUMMARY <br />Moisture Dry Wet <br />Content Density Density <br />($) (pcf) (pcf) <br />Low Wet Den. Value 1.1 76.4 77.24 <br />High Wet Den. Value 7.0 105.4 112.78 <br />Average 8.2 91.9 99.47 <br />Based on available piezometer (PZ) data, piezometric surface <br />topography and data graphs were generated and evaluated in an <br />attempt to define and model the piezometric surface within the <br />pile. A piezometric surface topography map is presented on Plate <br />2 in the Appendix. This topography was generated from piezometer <br />measurement data collected on January 14, 1994. Where conflicts in <br />the piezometric level exist (between adjacent well locations) only <br />the higher piezometric surface was modelled. The topography shows <br />a ridge or line of high pore pressure beneath PZs P-1, P-2 and P-3. <br />The topography also indicates that underdrain system No. 2 and to <br />a lesser degree underdrain No. 3, both seem to have a "drawdown" <br />effect on the piezometric surface within the pile. <br />In addition to topography mapping, the historic piezometer <br />measurement records were graphed on linear, time versus piezometric <br />surface elevation plots in order to readily identify anomalies <br />and/or trends in the piezometric level within the pile. Six <br />separate plots were evaluated with the data grouped according to <br />cross sections or piezometer locations in the pile, as described <br />below: <br />1.) The first graph considers only the three original <br />piezometers and is presented as Plate 3 in the Appendix. <br />This graph indicates that the water levels measured in <br />each of the piezometers (while at distinctly different <br />elevations) have moved in general concert with each other <br />1 <br />