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V1. SOIL PROFILE AND PERCOLATION TESTS A test pit was excavated to a depth of 8.0 feet to determine the soils profile in an area on parcel 1 that a septic system would likely be located. The test pit was excavated with a Cat 416 backhoe equipped with a 24 inch bucket. The depth of the test pit was limited due to difficulty in excavating. Visual classification of each soil stratum encountered was made in the field by a civil engineer at the time the test pit was excavated. A description of each soil encountered is contained in the Appendix as Log of Test Pit. For approximate location of test pit (TP) see Tentative Parcel Map in the Appendix. The surface soil consisted of a brown sandy silt for a depth of 1.5 feet. This was underlaid by a 2.0 foot stratum of very stiff sandy clay. The clay was underlaid by a fairly impervious stratum of gravel and cobble in a very firm and slightly cemented clayey sand matrix. This continued till the maximum depth explored of 8.0 feet. 5 Percolation tests consisting of a shallow (36 inches) and deep (25 feet) pit, were performed adjacent to the test pit. A deep pit percolation test was ran in conjunction with the shallow test because it was anticipated that the surface soils would be very slow to percolate. The test hole for the deep pit percolation test was also logged by a civil engineer. A description of each soil encountered is contained in the Appendix as Log of Deep Pit Percolation Test Hole. For approximate location of percolation test holes (PT) see Tentative Parcel Map in the Appendix. Both percolation tests were performed in 8 inch diameter test holes that had a 4 inch perforated pipe backfilled with gravel. Both holes were filled with water 24 hours prior to running the test. The last half hour of the tests readings were witnessed by a county health official and the test data obtained is enclosed in the appendix. A summary of the test results is presented next: Diameter of Depth of Test No. Hole (in.) Hole (in.) Percolation Rate (min/in) PT-1s 8 36 No Percolation PT-1d 8 300 1.0 There was only a .02 foot change in the water level of the shallow percolation test over the 4 hour time period of the test. This was as anticipated due to the stiff sandy clay encountered in the test pit. V1I CONCLUSION Based on the results of the shallow and deep percolation tests, the soil profile, and the performance of the septic systems in the surrounding area, it is our opinion that the new homesite resulting from the proposed parcel split should be suitable for the use of a septic tank, leach line, and dry well (25 feet deep) sewage disposal system. The proposed system however, should be properly designed and installed according to current San Joaquin County criteria. Based on the depth to ground water in the area, it is our opinion that the installation of the proposed septic systems, if properly installed, should not adversely affect the quality of the ground water in the area. / "W csso ' 3