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�[. ..i January 6,2000 Job Number. 599328 Page 5 One 25-foot soil boring was drilled in the proposed septic field area to characterize the soils. No ground water was encountered in the 25-foot boring. The soil layers encountered 60 consisted of the following: a dark brown to black sandy clay(0-9 ft),brown silty sand (9-11.5 ft), sandy silt (11.5-19.5 ft),brown sandy clay (19.5-23.5 ft), and a brown fine to medium sand with silt (25.5 to 25 ft). A"hard pan"layer was encountered at a depth of 4.5 feet (Plate 8). The sand with silt zone was found to be the most permeable therefore the percolation test was placed into that soil layer. One 4 hour percolation test was performed within the 25-foot soil boring in the designated septic field (Plate 1). The boring was 4.5-inches in diameter. Two inches of"pea gravel"was placed in the bottom of the hole. An open-ended 2-inch PVC pipe with slots on the bottom was ` installed into the hole and I to 2 feet of "pea gravel"was backfilled in the annular space. The 4- hour test was conducted in accordance with the requirements of the San Joaquin Division of Environmental Health. The following table summaries the test results: Summary of the Percolation Test Name. Location Depth of test Length Result Comments Date Tested P-I, Proposed septic 25 feet 4 hours 10.9 Result is the slowest interval recorded 12-16-99 field minlin for the 4-hour test rind VII. CONCLUSIONS AND RECOMMENDATIONS 6 In conclusion, a satisfactory percolation rate of 10.9 mintin at a depth of 25 feet was achieved within the proposed septic field. No shallow ground water was encountered during the on-site drilling. The estimated depth to ground water between Fall 1997 and Spring 1998 is estimated to range between 57 to 67 feet flowing in an east-northeast direction. An on-site water well is located over 100 feet from the proposed septic field. Dark brown to black colored surface clays were found to exist between 0 to 4.5 feet in depth. Due to the presence of these clays, the use of seepage pit(s) is warranted. These clays probably contain enough organic material to facilitate denitrification within the leach line trenches therefore no additional organic supplements are needed. �O[SSO ♦ 4 Z O . r,o�