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s v KLEINFELDER and significant loose material was removed from the bottom of the hole. The percolation tests were then prepared by first placing about 2 inches of fine gravel at the bottom of the holes and installing a 4-inch diameter, perforated PVC pipe. Before noon on July 21, 2005, about 12 inches of water was placed in the holes for pre- soaking. On July 22, 2005, the percolation tests were started at about 8:30 AM on July 22, 2005, in accordance with SJCEHD accepted guidelines, using clear potable �- water. None of the holes exhibited sloughing or caving. The holes were empty of water prior to testing. From a fixed reference point (a marked location on the side of PVC pipe), the drop in water level was measured in approximate 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel (SJCEHD Procedure #2). Under the observation of a representative from the SJCEHD, the last 30-minute reading of the four-hour period was used to calculate the percolation rate in minutes per inch. Because the permit does not allow three percolations to be performed, the SJCEHD representative only approved the test results for percolation test holes P-1 and P-3. A copy of our field percolation test result is attached on Plate 9. On December 12, 2005, another percolation test hole (P-4) was installed within the proposed leach field area at a depth of about 3'/4 feet below site grade. The percolation test was then prepared and performed in the same manner as percolation tests P-1, P-2, and P-3. r On July 26, 2005, samples of groundwater were obtained using clean procedures from a spigot at the head of the domestic well located near the existing residence. A permit for the well was not on file with SJCEHD. The water samples obtained from the well were delivered to a laboratory on ice that same day using chain-of-custody procedures _ for DBCP and nitrate (N) testing. The boring and percolation test holes were located in the field by visual sighting and/or pacing from existing site features; therefore, the locations shown on Plate 2 should be considered approximate. 6. GROUNDWATER Groundwater was not encountered in the soil profile boring drilled for this investigation. Lines of Equal Depth to Groundwater contour maps published in groundwater reports by the San Joaquin County Flood Control and Water Conservation District (1981 to 1999) show groundwater levels in the project area ranging from about 45 to 70 feet below ground surface. Based on Lines of Equal Elevation of Groundwater contour maps, the groundwater gradient in the project area is generally from Northwest to Southeast. Local gradient variations may occur due to well usage. 59149.G01/STOSR1062 December 15,2005 Copyright 2005 Kleinfelder, Inc. Page 3 of 7