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18340 E Rodeo Drive Project No.2018-00037 Page 5 <br /> the SRWCB of 10 mg/L-N and 45 mg/L, respectively. The lab results are included in <br /> Appendix B. <br /> 4.2 Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading <br /> analysis. The estimate of deep percolation of rain is based on the average monthly <br /> precipitation of rain fall for Lodi, California, based on the nearest weather station to the site <br /> available. The estimate first determines whether the average monthly precipitation exceeds <br /> average monthly potential evapotranspiration. If so, then the difference is potential deep <br /> percolation. This method does not consider runoff. See Plate 7 for the data and calculation. <br /> Average potential evapotranspiration was obtained from the California Irrigation <br /> Management Information System(CIMIS).The site is located within evapotranspiration zone <br /> number 12, as well as the Lodi station used in the analysis. The average rain fall for the Lodi <br /> area was obtained from the Western Regional Climate Center (www.wrcc.dri.edu) and was <br /> found to be 17.27 inches per year for the years 1893 through 2015. <br /> Based on this method, the average deep percolation of rain for the Lodi area is estimated to <br /> be 5.29 inches. The nitrate concentration of rain fall was estimated to be 1 mg/L-N <br /> (Hantzsche and Finnemore, 1992). <br /> 4.3 Current On-Site Sources of Nitrate <br /> The site has a three-bedroom single-family residence and a two-bedroom secondary <br /> residence - each with separate septic systems. One permit was obtained for the three- <br /> bedroom residence; according to the Permit No. SR0013983, the existing septic system has <br /> a 1600-gallon capacity with three 40-foot leach lines and three 25-foot deep seepage pits. <br /> The current two septic systems contribute to the current on-site sources of nitrate. <br /> Groundwater and rainfall are also recognized as potential current on-site sources of nitrate. <br /> 4.4 Future On-Site Sources of Nitrate <br /> 4.4.1 Quantity and Quality of Domestic Wastewater from Proposed Project <br /> The following discussion is for determining the long-term wastewater flow anticipated from <br /> the current three-bedroom and two-bedroom primary and secondary residential structures, <br /> as well as the proposed manufactured home with four bedrooms. The wastewater flow of <br /> both current dwellings and proposed dwelling will be incorporated into the subsequent <br /> nitrate loading analysis. The anticipated wastewater flow determined is not intended to be <br /> used for septic system design, because septic system sizing includes a peak use factor, <br /> whereas the numbers discussed herein are based on a long-term conservative measure of <br /> estimated effluent volume. <br /> Petralogix Engineering,Inc. <br /> 26675 Bruella Road,Galt,Ca 95632 <br /> (209)-400-5729 <br /> www43etraloglx.com <br />