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Geoelectric Leak Detection Final Report October 18, 2006 Forward Landfill WMU FU -06 Page 2 was checked periodically (at least every 20 minutes) by passing the equipment over a known hole or over a ground wire to confirm functionality of the equipment, and then again at the end of the day of surveying. The calibration holes were repaired by the Installer. Results The GCL underlying the sump area was determined to be too dry to conduct electricity during the calibration process. This area was therefore vigorously inspected visually for defects and one hole was found. The water lance survey of the remaining area of WMU- 06 did not locate any further holes. A description of the holes and locations are described in Table 1 and shown in Figure 2. 1 Panel 12 - Top of Sloe Calibration Hole 2 Panel 14 - Top of Sloe Calibration Hole over GCL 3 Corner of Sump Hole in extrusion weld The holes located were repaired by the Installer. Dipole Method for Geomembrane covered with soil material Method / Procedure The method used to perform the geoelectric leak detection survey on the soil covered geomembrane was the dipole method. Testing was performed in accordance with ASTM D7007-03. For this electrical leak location method, a voltage potential is introduced between the insulative geomembrane and the earth beneath it. In the case of holes in the geomembrane, current exits through the hole in the membrane, causing an anomaly in the voltage potential field at that location. Measurements of voltage potential are taken in a grid pattern throughout the survey area in order to locate these perturbations. The survey was performed by two dipole operators. The operators recorded and observed voltage potential measurements every meter in a grid pattern throughout the cell. As the operators proceeded, they observed the amplitude of change in voltage and watched for spikes or dips in the potential field. Whenever a significant change was encountered, the area was flagged and rechecked immediately until the anomaly could be validated or dismissed. A signal of greater than three times the background noise is validated when it can be reproduced at least five times over the same location. The surface of the cell was watered by the site water truck when conditions were dry to ensure electrical conductivity to the surface. Calibration Prior to the survey, a calibration test was performed to determine the minimum hole size that can be located by the dipole equipment and the maximum grid spacing for voltage measurements. The WMU FU -06 calibration was performed without watering the