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POGGIANO SOIL SUITABILITY STUDY Page No. 4 V. GROUND WATER DEPTH AND TESTING According to the map of "Lines of Equal Depth to Water in Wells" published fall of 1990 by the San Joaquin County Flood Control and Water Conservation District, the depth to groundwater at this location is 140+ feet. There is an operating well utilized by the existing home on the subject property. According to the Conditions of Approval prepared for the subject project, testing of the ground water was not required. VI. SOIL PROFILE AND PERCOLATION TESTS A 36 inch deep by 8 inch diameter test hole was excavated by hand for performing a shallow percolation test. It was apparent that the surface soils would be slow to percolate, so a 25 foot by 6 inch diameter test hole was drilled in order to perform a deep pit percolation test. The soil profile of the deep pit percolation test hole was logged by a civil engineer to determine the soil profile in the general area of the proposed septic system. A description of each soil encountered is contained in the Appendix as Log of Deep Pit Percolation Test Hole. For approximate location of the test holes (PT) see the Parcel Map in the Appendix. Two percolation tests were performed, consisting of a shallow (36 inches) and deep (25 feet) test. Two inches of gravel was placed in the bottom of each hole. A 3 inch diameter perforated pipe was then placed in each hole and backfilled with gravel. Both holes were filled with water 24 hours prior to running the tests. 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. The percolation rates have been adjusted to account for the gravel and pipe backfill. Calculations for adjustments are on the test data sheets. 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 36 580 PT-1d 6 300 23 As anticipated and due to the surface clayey soils, the shallow percolation test was very slow. A sand stratum was encountered in the deep pit from 22 to 25 feet. The deep pit percolation test was performed in this stratum, with a much more favorable rate. v 'I- D �+ Z W Q � P 9SS0G\