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• <br /> August 18,2014 <br /> Gibson Bluff <br /> L&A fob No. 14-056 <br /> Page 21 <br /> in millimeters of soil particles of 10%, 60%, and 90%, respectively, passing by weight, <br /> • <br /> and fr., is the fraction of the fines passing the No. 200 sieve by weight. The values of <br /> Dio , D64i D90, and fries are shown or obtained from test results on Plates A-I and A-2, and <br /> the determination of Kw for the three soil samples are shown in the table below. <br /> ESTIMATED INITIAL INFILTRATION RATES,Ksat <br /> Sample Test D10 D6o D90 (fines a Ksat Ksat <br /> No. Boring No, Size Size Size cm/sec in/hour <br /> 1 1 0.1654 0.750 11.5 0.054 0.0312 44.6 <br /> 2 2 0.1150 0.790 17.0 0.073 0.0194 27.7 <br /> 3 3 0.1171 0.425 1.25 0.063 0.0325 46,5 <br /> a login(Ksat) -1.57+ 1.90(D10)+0,015(D60) - 0.013(D90)—2.08(ffines) <br /> Recommended Design Infiltration Rate • <br /> We recommend the design infiltration rate for infiltration trenches-or galleries to be used. <br /> for onsite stonnwater disposal for the subject project be determined by taking the lowest <br /> value from the table above and apply a factor safety of 6 to it. Therefore, our <br /> recommended design infiltration rate in the advance outwash sand deposits would be 4.5 • <br /> iph (inches per hour), <br /> INFILTRATION TRENCHES/GALLERIES <br /> General <br /> It is our opinion that based on the soil conditions encountered by the test borings and the <br /> • results of particle size distribution tests on the soil samples, the targeted Esperance sand <br /> LIU & ASSOCIATES, INC. <br />