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CWDA No. 2 <br />901349 -0001 <br />06/11/11 <br />(S Iluddleston -Berg <br />F, - .T.- - -,rre <br />The monitoring report prepared by BGI is attached and the data is summarized in the following <br />table. The table includes corrected initial pore pressure values and corrected pore pressures for <br />the April monitoring. <br />VWP ID <br />Initial Pore <br />Pressure <br />(psi) <br />4/21/14 Pore <br />Pressure <br />(psi) <br />5121/14 Pore <br />Pressure <br />(psi) <br />,Difference Since <br />Installation. <br />(si <br />Difference Since <br />Last Reading <br />(psi) <br />VWP -05 <br />6.8 <br />2.0 <br />1.9 <br />-4.9 <br />0.0 <br />VWP -06 <br />11.3 <br />14.8 <br />14.6 <br />+3.5 <br />+0.2 <br />VWP -08 <br />8.2 <br />8.7 <br />8.9 <br />+0.7 <br />+0.2 <br />VWP -09 <br />2.8 1 <br />2.9 <br />2.8 <br />0.0 <br />-0.1 <br />VWP -10 <br />-1.9 <br />1 -19 <br />-1.9 <br />0.0 <br />+0.t <br />Discussion <br />As indicated in the referenced report, the stability of CWDA No. 2 is sensitive to increases in <br />pore pressures in VWP -08. An increase in the pare pressure of 7 psi in VWP -08 would result in <br />a reduction of the Factor of Safety to below 1.5. <br />As indicated in the monitoring data, very slight increases in pore pressures were reported in <br />VWP -06, VWP -08, and VWP -10. A very slight decrease in pore pressure was reported in VWP - <br />09 and the pore pressure in VWP -05 was unchanged over the one month period. <br />In general, based upon the results of the recent pore pressure monitoring data, HBET does not <br />believe that there is any reduction in the stability of CWDA No. 2. In addition, based upon the <br />errors identified by BG1 resulting in lower pore pressures in VWP -08, VWP -09, and VWP -10, <br />HBET does not believe that ongoing monthly monitoring is warranted. Quarterly monitoring is <br />recommended. <br />We are pleased to be of service to your project. Please contact us if you have any questions or <br />continents regarding the contents of this report. <br />Respectfully Submitted: <br />Huddlestulr(Bel)y Engineering and Testing, LLC <br />� <br />9g110 <br />s <br />ANAL <br />Michael A. Berry, F.E. <br />Vice President of Engineering <br />X:12003 ALL PRQJECTS1.00159 - JE Stover Associates 1nc',00439.0003 Bowie ivline?2OO - Geo1Gob 2100499 -0003 LR061114.dm 2 <br />