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• levels measured in the test holes/monitor wells, as well as the number of days after drilling that the <br />measurements were taken are shown on the Logs of Exploratory Test Holes (Figures #3 and #4). <br />Based on our measurements, it appears that the groundwater was encountered in all of the test holes drilled <br />within or near the slide area near the bottom of the fill materials or in the natural clays or weathered bedrock <br />materials. The groundwater was encountered at depths ranging from 4 to 23 feet beneath the ground surface at <br />the time of drilling. The groundwater levels rose considerably over time in all of the wells. Based on our most <br />recent measurements, it appears that the groundwater levels in a majority of the wells have stabilized and are <br />situated within 5 to 10 feet of the existing ground surface. It should also be noted that groundwater levels in <br />test holes 2, 3 and 6 were within 1 foot of the ground surface. In addition, groundwater seepage is daylighting <br />in several areas across the failure area. A Potentiometric Groundwater Surface map has been prepared based <br />on the groundwater levels measured at the time of drilling and is shown in Figure #9. <br />As noted above, NWCC, Inc. also measured and observed the PVC casing to determine if any soil movement <br />had occurred within the PVC casing that was installed in the test holes. Soil movement/deflection of the PVC <br />casing was observed in all of the test holes/wells installed in the slide area within 65 to 70 days after the <br />drilling was completed and the wells were installed. The deformations were observed at various depths in the <br />weathered bedrock materials that are overlying the claystone bedrock materials. The depths at which the <br />movement was observed ranged from 9 'V2 to 27 '/s feet beneath the existing ground surface. The depths at <br />which the movement/deformation was observed and the number of days after the installation of the wells that <br />the movement was recorded are shown on the Logs of Exploratory Test Holes (Figures #3 and #4). <br />Slope Failure Analysis <br />Based on the results of the field and laboratory investigations and our experience with similar types of slope <br />failures, we believe the slope failure that has occurred above Pond 16 can be characterized as a moderately <br />sized translational slide that appears to have occurred in the weathered claystone materials. A translational <br />slide is defined as a failure along a planar surface. The planar surface in this area is the contact zone between <br />the highly weathered claystone materials and the underlying claystone bedrock materials. <br />Based on the movement and displacement in the PVC test hole casings that were installed in the slide in <br />September, 2008, it appears that the failure plane is situated between 7 and 29 feet of the existing ground <br />surface and in the weathered claystone materials. Based on the subsurface conditions encountered in the test <br />holes and pits, and our observations made of the site, we believe that the failure is likely to propagate further to <br />• the northeast and uphill. Additional downslope movement of the debris flow at the base of the failure area will <br />Job Number: 08-8099 NWCC, Inc. Page 7