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Soil Suitability and Nitrate Loading Evaluation-Update-2 Page 12 of 18 <br /> Great Pacific Nut—Nut Processing Facility Expansion <br /> 3501 Lehman Road, Tracy, California <br /> September 6, 2019 CTE Job#25-0710G <br /> practice that a minimum factor of safety of 2 be utilized in storm water infiltration design. <br /> Therefore based on the infiltration rates observed in P-3 and utilizing a factor of safety of <br /> 2, a design infiltration of 9.6 gal/sf/day is recommended in the vicinity of P-2 and P-3 for <br /> the proposed storm drainage system as indicated in Table 3.3 below. <br /> TABLE2.3 <br /> OBSERVED <br /> TEST NUMBER DEPTH MATERIAL TYPE PERCOLATION INFILITRATION <br /> RATE(Min/In) RATE <br /> (gal/ft2/day) <br /> P-1X(Leach Field) 30-36 in CL(CLAY) 480 0.38 <br /> P-2(Drainage Basin) 9.5-10.0 ft SM(SILTY SAND) 6.67 29.92 <br /> P-3(Drainage Basin) 9.5-10.0 ft SM(SILTY SAND) 10.0 19.23 <br /> P-1 (Leach Field) 32-38 in ML(SANDY SILT) 16.0 12.82 <br /> RECOMMENDED STORM DRAINAGE DESIGN INFILTRATION RATE= 9.6 <br /> 8.0 NITRATE LOADING CALCULATIONS <br /> Per SJEHD requirements, the following summarizes our nitrate loading calculations for <br /> the proposed leach field. The state drinking water standard for nitrate is 45 milligrams <br /> per liter (NO3) and 10 mg/1 as Nitrogen (N) in groundwater. Presented below is our <br /> evaluation of nitrate loading which uses the Hantzshe mass balance equation (source: <br /> Predicting Groundwater Nitrate-Nitrogen Impacts, Hantzsche and Finnemore; 1992) <br /> attached as Appendix C. <br /> NC = Calculation of nitrate-nitrogen in groundwater resulting from leach field <br /> source and precipitation (mg/l, as N). <br /> NC _ [I (NW) (1-D)+R(Nb)] /(I+R) <br /> I1 = Volume rate (Gal/day) of waste water entering the soil from 12 employees <br /> (verified by owner) and"Industrial Building No Food Cafeteria"=15 <br /> gal/per person: 12 x 15 = 180 gal/day. <br /> Iz = Volume rate (Gal/day) of waste water entering the soil from existing <br /> single family dwelling: 2 bedrooms x 150 gal/day=300 gal/day. <br /> SACRAMENTO • FREMONT • MODESTO <br /> INSPECTION&TESTING•GEOTECHNICAL•ENVIRONMENTAL•CONSTRUCTION ENGINEERING <br />