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�■ KLEINFFLDER We anticipate that waste disposal for the residences and clubhouse will be provided by individual on-site sewage disposal systems. We anticipate that disposal trenches may be cut deep in order to intersect suitable percolating soils or shallow leach lines will lead to seepage pits for disposal of effluent. 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 initially explored on November 27, 2001, by drilling one boring to a depth of approximately 15 feet below existing grade in the area of the proposed residential leach field. Following drilling, t us boring was used for percolation test P-1. The boring was drilled using a Simco 2400 truck-mounted drill rig equipped with -mc�i O.'solid- stem auger. During the same time period, a second percolation boring (P-2) was drilled to a depth of about 3.5 feet below site grade. The location of the percolation tests Is a proximately 150 feet east and 60 feet 1 sou of t 1e private well adjacent to the proposed residence location. On January 31, 2002, two additional percolation borings (P-3 and P-4) were drilled within the proposed clubhouse leach field area. The approximate percolation tests locations are presented on the attached plate. P- 2 V, p�— 1� !-� 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 low plastic clayey sands to a depth of about 8.5 feet, followed by silty and relatively "clean" sands to the depth explored. A log of boring that describes the subsurface conditions encountered in the proposed residential leach field area is attached. The percolation tests were performed on November 28, 2001 and February 1, 2002, 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 a head of water above the gravel to the hole. From a fixed reference point, the drop in water level is measured in approximate 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 Services Department Environmental Health Division (SJCEHS/EHD), 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 is attached. 20-4685-O1.G01/2002R367 April 18,2002 ©2002 Kleinfelder,Inc. Page 2 of 5