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SA KIJ OA Q U I N Environmental Health Department <br /> l" g COUNTY Linda Turkatte, REHS, Director <br /> Greatness grows here. Kasey Foley,REHS,Assistant Director <br /> PROGRAM COORDINATORS <br /> Robert McClellon,REHS <br /> Jeff Carruesco,REHS, RDI <br /> July 6, 2019 Willy Ng,REHS <br /> Muniappa Naidu, REHS <br /> Michael Kith,REHS <br /> Don Chesney, PE <br /> Chesney Consulting . <br /> PO Box 3794 <br /> Turlock, CA 95381 <br /> RE: Soil Suitability/Nitrate Loading Study <br /> Decentralized Wastewater Management System Design <br /> 7979 S Airport Way, Stockton <br /> APN 177-050-08, SR0080316, SR0080336 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed the Soil <br /> Suitability/Nitrate Loading Study (SSNL) and the Decentralized Wastewater Management System <br /> Design submittal, dated March 4, 2019, and submitted March 15, 2019 for the above noted location <br /> and has the following comments for your consideration. <br /> • The SSNL was prepared to determine the suitability of the above noted parcel for onsite <br /> wastewater treatment system (OWTS) usage, including to estimate the potential for nitrate <br /> impact to groundwater, for a proposed cannabis greenhouse cultivation and processing <br /> facility with up to a maximum of 20 employees and visitors. <br /> • The shallow percolation test showed a result of 83.3 minutes per inch. A deeper percolation <br /> test was not performed to indicate the soil at greater depth would be suitable for OWTS usage. <br /> The OWTS design provided in the SSNL Study used standardized design criteria from the <br /> San Joaquin County OWTS Standards for a standard OWTS for areas where the percolation <br /> test result is less than 60 minutes per inch. According to the San Joaquin County OWTS <br /> Standards, Section 3.8.7, an OWTS in an area with a percolation test result of 83.3 must be <br /> mitigated with the OWTS design. The State Water Resources Control Board's (SWRCB) <br /> OWTS Policy, Table 3, provides an application rate of 0.123 gallons per day per square foot <br /> for a percolation rate of 83 minutes per inch. A design for the OWTS dispersal field and 100% <br /> replacement based on this application rate would be acceptable. <br /> • San Joaquin County OWTS Standards, Section 9.11.4 require sumps greater than eight feet <br /> in depth be no closer than ten feet above seasonal high water table. The San Joaquin County <br /> Flood Control and Water Conservation District's Lines of Equal Depth to Water In Wells, <br /> Spring 1983, shows depth to water to be approximately 20 feet below grade. The maximum <br /> depth of sumps that can be used at the site is 10 feet. <br /> • The location identified in the SSNL Study for the OWTS dispersal field for the project is an <br /> area identified in the project site map to be used as a parking lot. This area is not suitable for <br /> OWTS usage. An area suitable for the full initial dispersal field and the 100% future <br /> replacement area must be identified on a site map for the project in an area where it will not <br /> be driven over, parked on, used for storage, or used any other purpose than for OWTS <br /> dispersal. The site map must be drawn to scale and must show all proposed development <br /> 1868 E. Hazelton Avenue I Stockton, California 95205 1 T 209 468-3420 1 F 209 464-0138 1 www.sjcehd.com <br />