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Soil Suitability and Nitrate Loading Evaluation-DRAFT Page 6 of 18 <br /> Great Pacific Nut—Nut Processing Facility Expansion <br /> 3501 Lehman Road, Tracy, California <br /> MM 15, 2019 CTE Job 4 25-071 OG <br /> 7.2 Percolation and Infiltration Rates <br /> The soil percolation rate is defined by the average time in minutes for a 1-inch column of <br /> water to "seep" into the soil. Percolation rate was calculated in minutes per inch (MPI) <br /> by dividing the time (in minutes) by the change (drop) in water level (in inches). No <br /> correction factor was used in the calculation for boring diameter. - -77--)._ - - ( <br /> Percolation test"P-1" achieved a steady percolation rate of 480 minutes/inch at 3.0 ft bgs. <br /> "P-2" achieved a steady percolation rate of 6.67 minutes/inch at 10.0 ft bgs, and, "P-3" <br /> achieved a steady percolation rate of 10.0 minutes/inch at 10.0 ft bgs. In general, the <br /> percolation rates are not considered inconsistent with those typical of the soil types <br /> encountered at the site/vicinity. <br /> Owing to the very slow percolation rate that was determined at P-1 (at leach field), the <br /> San Joaquin County Environmental Health Department inspection was postponed until an <br /> alternative system is designed. The existing permit and associated county inspection, is <br /> expected to be available for an additional percolation test which could be performed at an <br /> alternate depth or location when appropriate changes have been determined. <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, Hantzshe and Finnemore; 1992). <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 /> I = Volume rate (Gal/day) of waste water entering the soil. <br /> Based on the following assumptions: <br /> 2 dishwashers (10 Gal/use): 2 x 2 per day x 10 Gal=40 Gal/day <br /> Two Comm. sinks: (20 Gal/use): 2 x 2 per day x 20 Gal= 80 Gal/day <br /> SACRAMENTO • FREMONT • MODESTO <br /> INSPECTION&TESTING•GEOTECHNICAL-ENVIRONMENTAL•CONSTRUCTION ENGINEERING <br />