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Soil Suitability Study 33233 S.Koster Rd., Tracy, CA Page 7 Section 6.5 Conduct of The Percolation Test At 7 A.M. on November 2, 2011, water was again added to the test holes until the bottoms of the holes were submerged to a minimum depth of 6 inches. A piece of timber was then set over each hole to provide a fixed reference elevation for measuring the rate of fall of the surface of the water in the test holes. The increase in the depth from the reference elevation to the surface of the water in the test hole was then measured at approximate 30 min. intervals over a period of four hours. During that period the test holes did not run dry. The depths to the surface of the water in each test hole and the time at which the depth measurements were made were recorded on the Percolation Test Foran. Section 6.6 Complete Percolation Test Form — The completed Percolation Test Form is included in the Appendix. The form is signed the San Joaquin County Environmental Health Department resentative.who observed the testing. Section 6.7 Discussion of Potential Problems 0The low percolation rates computed from the tests (See Sectiiii ) are typical for thesilty clay soils present beneath the site. Although the measurerates are low, as isfurther discussed in Section 6.8 below, the long term successff the existing septicsystems on Parcel 1 of the property demonstrates that should ansysteiedon Parcel 2 or the Designated Remainder theyold operateblem . However, to comply with San Joaquin County regulations, any such future systems should_be_a redia California Registered Professional Engineer. — --- Section 6.8 Discussion of Percolation Rates in Relation to Tyne Size and Location of Future Le Fields The percolationrates co nputed from tests are as follows: — Parcel Percion Rate Parcel 1 256 minA Parcel l 293 min./in Designated Remainder 280 min./in. These results are typical for silty clay soil. However, it is important to note that at the time the percolation tests were conducted the soil to a considerable depth below the ground surface was only partially saturated. The hydraulic conductivity of partially-saturated soil is very low, but if the soils become fully saturated, as would occur below and around a septic leach field, the / hydraulic conductivity would increase by orders of magnitude with a corresponding large increase in the percolation rate. This condition is well demonstrated by the successful operation of the existing septic tank and leach field systems on Parcel 1 of the property that operate