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<br />CONCLUSIONS AND RECOMMENDATIONS: <br />' The Phase I investigation had identified several possible <br />explanations for the existence of seemingly anomalous pore pressure <br />readings in the original open well piezometers including a layered <br />' aquifer system, residual pore pressures remaining in impervious <br />materials from construction effects, or the influence of water <br />seeping from ditches collecting surface seepage. The Phase II <br />geotechnical investigation provided a significant amount of very <br />' valuable information with respect to defining the possible <br />mechanisms of water flow and pore pressures within CRDA No. 1. <br />These mechanisms appear to be comprised of a variable system of <br />' pervious interconnecting conduits or channels and disjointed <br />horizontal boundaries of low permeability, located at various <br />discrete depths within the pile. The piezometric system can most <br />simply be likened to a multi-tiered system in which water flows <br />from a source and cascades from tier to tier until it finally <br />reaches the bottom and drains away or daylights on the slope. In <br />the case of the pile it appears that moisture which infiltrates <br />' from its surface moves through the pile via a changing network of <br />pervious conduits or channels and pools on various discrete <br />horizontal boundaries of lower permeability. As pore pressures <br />t build upon the horizontal boundaries, connections in the form of <br />pervious conduits are created which relieve pressure and allow <br />moisture to drain to the next lower boundary. These assertions can <br />' be substantiated by the following observations: <br />1. The highly heterogeneous structure of the pile as evidenced by <br />the results of drilling operations in which presumed aquifers <br />' were not intercepted in expected locations and the highly <br />variable drilling conditions with respect to moisture content <br />and material consistency. <br />' 2. The observation of typical pile placement techniques on CRDA <br />No. 2 in which refuse material is placed with end dump trucks <br />forming rows of small individual piles of refuse material <br />' which are subsequently leveled and compacted with a dozer. <br />Considering this placement technique it is quite conceivable <br />that coarse material falls to the perimeter of abutting <br />' individual dump piles and is covered with fine grained <br />material as the dump piles are leveled. Also, the material <br />itself can vary widely in permeability characteristics <br />' depending on material encountered in the mining operations. <br />Thus, an interconnected network of coarse material is formed <br />which possibly leads to the future creation of pervious paths <br />or conduits within the pile as moisture is introduced. <br />' 3. From piezometer data collected during the present <br />investigation it appears interconnections between boundaries <br />' open and close with unpredictable regularity due to piping and <br />migration of fine material through open zones. <br />30 <br />