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DER 6.i �Bn'9tYMpk-PINI(SOFrtbi2 I` Following completion of the soil profile borings, percolation test holes P-1, 15-2, and'P-3 were�dfille -lfvithin each proposed parcel to depths of 3 feet, 3 inches; 3 feet, 4 inches; and 3 feet,+3 inches below site grade. The percolation holes were drilled using a 4-inch diameteYb_ nd'auger. The approximate percolation test hole locations are presented on Plate,2' Following drilling, the sides of the test holes were scored, and significant loose material was removed from the bottom of the holes. The percolation test holes were then prepared by first placing about 2 inches of fine gravel at the bottom of the holes and installing a 2-inch diameter, perforated PVC pipe. Before noon on July 20, 2008, ` about 12 inches of water was placed in the holes for pre-soaking. On July 21, 2008, the percolation tests were started at about 8:20 AM in accordance with SJCEHD accepted guidelines, using clear potable water. The holes did not exhibit sloughing or caving and 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 4 hours (SJCEHD Procedure No. 2), refilling as necessary to maintain the prescribed amount of water over the gravel. Under the observation of a representative from the SJCEHD, the last 30-minute readings of the tests were observed and the percolation rates, in minutes per inch, were calculated. Copies of our field percolation test results are attached on Plates A-6 and A-7 of Appendix A, 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. 7. GROUNDWATER., Groundwater was not encountered in our soil profile borings 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 60 to 70 feet below,/ ground surface. Lines of Equal Elevation of Groundwater conidur maps published in'`_--' groundwater reports by the San Joaquin County Flood Control and Water Conservation District (2003) show the groundwater gradient in the project area is generally to the north-northeast. Local gradient /a ttions may occur due to well usage. We understand that the existirf wells ocated the northern property will be used to supply water:f r domestic uses xcepdrinking. We understand bottled water is used Lfor drinking. We anticipate that the predominant use of groundwater will be for domes ';er(sampled ricultural, fire, and 'landscaping-purposes. Thresf the groundwater analysis to determine the concentrations of nitrate L in the from the on-site well indicated a concentration ranging from to \� 5.2 mg/I. This nitrate concentration is less than the state drinking water standar of 151- ' mg/l. .-DBCP was not present in detectable amounts with a reporting limit of 0.01 N /I. Gooies of the test results are presented in Appendix D. 95671.G01/ST08R738 "IL gust 1 ®2008 Kleinfelder 'l� age 4 of 6 L