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KLEINFELDER HISTORICAL GROUNDWATER DEPTH According to groundwater reports published by the San Joaquin County Flood Control and Water Conservation District (Spring 1993 to Spring 1999), high groundwater in the project area has been recorded at depths in the range of about 60 to 70 feet below ground surface. FIELD EXPLORATIONS AND TESTING The subsurface conditions at the site were explored on November 27, 2001, by drilling one boring to a depth of approximately 15 feet below existing grade, which was used for a percolation test. The boring was drilled using a Simco 2400 truck-mounted drill rig equipped with 6-inch O.D. solid-stem auger. During the same time period, another percolation boring was drilled to a depth of about 3.5 feet below site grade. The location of the percolation tests is approximately 150 feet east and 60 feet south of the private well adjacent to the proposed residence location. The approximate percolation tests locations are presented as P-1 and P-2 on the attached plate. Based on our findings, the subsurface soils encountered consisted of sandy clay to a depth of about 3 feet over approximately 1 foot of hardpan. These soils were underlain by silty and clayey sands to the depth explored. A log of boring that describes the subsurface conditions encountered is attached. As requested, we also attempted to perform percolation tests north of the gravel parking area for the proposed clubhouse, however, the soft, wet ground would not support the drill rig. Per our subsequent conversation with Brad Norgard, we will attempt to perform those percolation tests at a later time whe�egr�and dries up or equipment is brought in to remove the soft surficial soils. y//y f� The percolation tests installed for the r sidence were p rf� ormed in accordance with accepted guidelines using clear potable water. The procedure calls for first placing about 2 inches of fine gravel at the bottom of the bore hole. The hole is then pre-soaked with water at least 24 hours prior to performing the test. The test is performed by first adding about 6 inches of water per 3 foot of percolation test depth above the gravel to the hole. From a fixed reference point, the drop in water level is measured in approximately 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel. Under the observation of a sanitarian from the San Joaquin County Public Health Department (SJCPHD), the last 30- minute reading of the four hour period is recorded and used to calculate the percolation rate in minutes per inch. The estimated percolation rates are summarized below. A copy of our field percolation test results for test numbers P-1 and P-2 is attached. Test Number Depth, ft. Percolation Rate min./inch P-1 15 6.7 P-2 3.5 Did not percolate 20-4685-01.G01/2011R1543 December 12,2001 O 2001 Kleinfelder,Inc. Page 2 of 4