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i <br /> i <br /> November 20, 2019 <br /> FOR: San Joaquin County Environmental Health Department <br /> Mr. Michael Kith, Program Manager <br /> 1868 Hazelton Ave. <br /> Stockton, CA 95205 <br /> PROJECT: Navu Farms,Inc. <br /> 7300 West Delta Avenue <br /> Tracy, California 95304 <br /> APN: 213-020-41, SR0081147, PA1800316 <br /> SUBJECT: Response to Soil Suitability/Nitrate Loading Studies/OWTS Design Report <br /> I submitted the above-referenced Studies/Report/Design Plans pertaining to this project to EHD <br /> on September 11,2019. The following is my response to the comments of EHD's outside <br /> consultant, Questa Engineering Corporation, received on November 19, 2019. <br /> The main issue with the OWTS Design is the separation distance between the floor of the <br /> leachline trenches and the observed depth to the water table, which was directly measured to be <br /> 5.7 feet below grade. Separation distances are to be based upon the percolation test rate obtained. <br /> This regulation was actually promulgated by the State Water Resources Control Board OWTS <br /> Policy: Quality Control Policyfor Siting, Design, Operation, and Maintenance of'Onsite <br /> Wastewater Treatment Systems. My design incorporated a five-foot separation distance, instead <br /> of an eight-foot separation distance. This eight-foot separation distance is based on the obtained <br /> perc rate of 20.8 min/in. While I was aware of this EHD regulation, I present the following <br /> response: <br /> 1. This regulation is absurd simply due to the fact that every project is site-specific in terms of the <br /> on-site soils and project wastewater flow volumes. This is why a civil engineer for a project <br /> should make these site-specific determinations of the soils and project wastewater flows. The <br /> onsite soils at proposed leachline trench depth for this project were determined to be a clay loam, <br /> with 29%clay,48% silt and 23% sand contents. This soil structure has three primary benefits: <br /> First, this soil structure mitigates saturated flow conditions; one of the biggest concerns of the <br /> Water Board. Taking the project wastewater flows into account, the flow volumes will be <br /> extraordinarily low, as low as 5-10 gpd, giving the receiving soils ample time and space to process <br /> the incoming effluent. Second, the clay content of the native soils is biologically active and <br /> consequently, beneficial for the destruction of bacteria and viruses. Thirdly,the clay content is <br /> very favorable for the mitigation of nitrate loading by impeding nitrification and promoting <br /> denitrification, as stated in my report. <br /> Page 1 of 3 <br /> T.C..2ex 3794 + .1 uv&d,ea 95381 + (209)402-9652 + ddr$e6ng4Aia%tmnd <br />