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,4 SAN -,10A0UIN Environmental Health Department <br /> Il COUNTY <br /> •� � Jasjit Kang, REHS, Director <br /> cq ?vi Greatness grows here. MuniappaNaidu, REHS,AssistantDirector <br /> PROGRAM COORDINATORS <br /> Jeff Carruesco, REHS, RDI <br /> Willy Ng,REHS <br /> Steven Shih, REHS <br /> Elena Manzo, REHS <br /> Natalia Subbotnikova, REHS <br /> July 8, 2026 <br /> ABBY RACCO <br /> LIVE OAK GEOENVIRONMENTAL <br /> 407 W. OAK STREET, <br /> LODI, CA 95240 <br /> RE: Soil Suitability and Nitrate Loading Study <br /> 23304 S. Hansen Road, Tracy CA 95304 <br /> SU-2601418, APN: 209-360-02 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed the Soil Suitability and <br /> Nitrate Loading (SSNL) Study dated June 22, 2026, and submitted June 25, 2026, and has the following <br /> comments for your consideration. <br /> The SSNL was prepared to determine the suitability for onsite wastewater treatment system (OWTS) <br /> usage and the potential long-term impact of nitrate to groundwater from the existing four-bedroom home <br /> and proposed new two-bedroom ADU. The parcel size is 1.64 acres. <br /> Based on the information provided, the EHD can make the following findings: <br /> 1. The SSNL reports a nitrate-loading estimate for the existing and proposed ADU OWTS of 12.7 <br /> milligrams per Liter (mg/L) of NO3-N (Nitrate as Nitrogen); the maximum contamination level for <br /> NO3-N in groundwater is 10.0 (mg/L) set by the Central Valley Regional Water Quality Control <br /> Board. As stated in the report, an oversized septic tank may be utilized in cases where a 30 <br /> percent reduction would bring the nitrate loading under the MCL. The septic system construction <br /> shall follow the San Joaquin County OWTS where applicable. (SJC OWTS Standard 7.1). <br /> 2. Based on the information provided the EHD finds that the SSNL Study supports the suitability for <br /> standard OWTS usage for the proposed development pursuant to San Joaquin County <br /> Development Title, Section 9-604.010(d)with the installation of an oversized 2,000-gallon septic <br /> tank. <br /> 3. The Percolation test conducted on June 5, 2026, yielded a percolation rate of 6.94 minutes per <br /> inch (MPI). At this rate, a minimum of 8 feet of soil separation is required between the bottom of <br /> the dispersal field and the groundwater as mitigated by the proposed standard septic system. The <br /> SSNL reports groundwater level at about 15 to 20 feet below surface grade. (San Joaquin County <br /> OWTS Standard Table 1.10.2). <br /> 4. Obtain an installation permit for the residential onsite wastewater treatment system (OWTS) from <br /> EHD. Inspection is required before backfilling of OWTS excavations. Request inspection 24 hours <br /> in advance by calling the inspection line (209) 953-7697. (SJC OWTS Standard Section 2) <br /> 1868 E. Hazelton Avenue I Stockton, California 95205 1 T 209 468-3420 1 F 209 468-3877 1 www.sjgov.org/ehd <br />