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October 18, 2006 <br />Job No. 021605.07 <br />Mr. Lochlin Caffey <br />Forward Landfill, Inc. <br />9999 Austin Road <br />Manteca, California <br />Re: Geoe/ectric Leak Detection Surveys — WMU FU -06, Forward Landfill <br />Dear Lochlin, <br />This report documents the geoelectric leak detection surveys conducted by Vector <br />Engineering Inc/Solmers (Vector/Solmers) on the 60 -mil geomembrane for WMU FU -06 at <br />the Forward Landfill. Vector/Solmers conducted the survey on the exposed <br />geomembrane from September 11 to September 15, 2006 and then after it was covered <br />with gravel and soil operations layers from October 4 to October 10, 2005. The area <br />surveyed was approximately 460,000 sf. This report describes the methods, procedures, <br />® calibrations and results of the two surveys. <br />Water Lance Method for Exposed Geomembrane <br />Method / Procedure <br />The method used to perform the geoelectric leak detection survey on the exposed <br />geomembrane was the water lance method. Testing was performed in accordance with <br />ASTM D7002-03. The water lance leak detection technique consists of the application of a <br />difference in electrical potential between the surface under the geomembrane and a water <br />jet sprayed onto the surface. Geomembranes prevent the flow of electrical current. In the <br />event a leak is present, the water becomes in contact with surface below the <br />geomembrane and thus allowing the flow of electrical current. A current detector informs <br />the operator via visual and audio signals of the presence of a potential leak. The leak is <br />localized and identified by the operator and documented on the daily report. <br />In addition to identifying leaks in the geomembrane, the operator will identify any <br />irregularities in the subgrade that may affect the geomembrane. These irregularities are <br />not leaks, however they are identified for the installer and CQA personnel to evaluate and <br />repair, if necessary. <br />Calibration <br />The equipment was calibrated by making a 1 mm hole in the geomembrane and adjusting <br />the sensitivity of the leak detection equipment to detect the hole when passed over it. This <br />procedure was conducted each day prior to beginning work. In addition, the equipment <br />