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July 21, 2014 <br /> Two Single-Family residences <br /> L&A Job No. 14-065 <br /> Page 23 <br /> the soil samples can be determined by interpolation according to their Dlo sizes. The <br /> recommended infiltration rates of the soil samples thus determined are listed in the table <br /> below. <br /> b ESTIMA'1'Ell INFILTRATION RATES <br /> Sample Test D1�, Estimated Long-Term <br /> No. Pit No. size Infiltration Rate, Inch/Hour <br /> 1 2 0.0486 0.78 <br /> 2 3 0.1351 2.53 <br /> b Based on Dlo size of soil samples <br /> Recommended Design Infiltration Rates for Infiltration Trenches <br /> The design infiltration rates shown on the above table should be used for design oi' <br /> infiltration trenches to be installed near the test pits from which the soil samples were <br /> obtained. The bottom of infiltration trenches should be excavated at least 6 inches into <br /> the target advance outv✓ash sand deposit from which the soil samples were obtained. <br /> Infiltration Trench Construction <br /> The soil unit at bottom of infiltration trenches should be verified by a geotechnical <br /> engineer. The stability of the trench cut bank should also be verified by a geotechnical <br /> engineer during excavation. The infiltr.ation trenches shauld be set back at least S feet <br /> from property lines and 10 feet from nearby building footing foundations +�r utility <br /> trenches. Also, the bottom of infiltration trenches should be lower than the adjacent <br /> footing foundations and utility trenches. <br /> LIU & ASSOCIATES, INC. <br />