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<br />1 <br />To date, a total of 19 piezometers with varying bottom or tip <br />' elevations, have been installed to monitor the piezometric levels <br />within the pile. The designation and location of existing <br />piezometers is shown on Plate 1 in the Appendix. Four piezometers <br />' are located along the west toe of the slope, eleven are located on <br />or near the first slope bench (approx. elev. 4880) and the final <br />four are located on or near the second slope bench (approx. elev. <br />4910). Three of the eleven devices located on the first bench were <br />' installed in or about 1985 to an approximate depth of 30-feet, the <br />most southerly of which (P-1) has consistently revealed an apparent <br />piezometric surface somewhat higher than the original slope design <br />' anticipated. In apparent response to the P-1 piezometer <br />measurements another piezometer (P-la) was installed approximately <br />250-feet to the south in 1991. The remaining devices have been <br />' installed within the last 6-months (Summer 1993). In general the <br />installations are open-well type piezometers which consist of 2- <br />inch diameter slatted PVC pipe installed in 4-inch diameter drill <br />holes. From discussion with Mr. Reschke the 2-inch PVC pipes are <br />' slotted or perforated for their entire length and there were no <br />special requirements to fill the annular space between the drill <br />hole and the slotted pipe, isolate the moisture influence zone at <br />' the tip or seal the piezometer tube at the ground surface. The <br />piezometers have been measured on a quarterly schedule, if not more <br />often. All piezometers appeared to be intact and functioning <br />properly. <br />1 Several seepage areas were identified and pointed out during <br />the inspection. Though most areas were not actively seeping, their <br />' existence was evidenced by traces of vegetation normally associated <br />with wet or saturated soil conditions. Surface seepage was, <br />however, observed flowing, south, along the inside alignment of the <br />' first slope bench (elev. 4880) at an estimated rate of 1 GPM. Even <br />though it had been, and was, snowing lightly during the inspection, <br />Mr. Reschke noted that this (flow) was a somewhat common condition. <br />Again, vegetation was present along the alignment of this flowing <br />' drainage. It appeared that the majority of the seepage and seepage <br />evidence was located in the vicinity of the first slope bench. The <br />seeps appear to issue from points 5 to 10-feet (vertically) above <br />' the elevation of the bench. <br />No obvious source of the seepage was observed. It has been <br />' hypothesized that the surface seepage is a manifestation of perched <br />zones or aquifers within the pile which are charged from surface <br />moisture collected by or around the pile. Considering the method <br />of refuse placement (large horizontal lifts); the assumed diversity <br />' of refuse material characteristics; the issue elevation (relatively <br />high in the pile); and the apparent intermittent nature of seepage, <br />this explanation is quite plausible and will be expounded upon in <br />' consideration of the present stability analyses. Placement and <br />compaction of material in horizontal lifts tends to create a higher <br />horizontal than vertical permeability, even in uniform material. <br />In addition, it is reasonable to assume that, periodically, the <br />2 <br />1 <br />