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r`�2 INTRODUCTION Mr. Salvador(Sal) Serna is proposing to install a modular(manufactured)three bedroom home on property he owns,referenced on the Title Page. This proposed modular home is considered a Second Unit Dwelling(a.k.a. Accessory Dwelling Unit)by San Joaquin County since there is an existing Single Family Residential (SFR) structure on the property. The San Joaquin County Environmental Health Department(EHD)required a Soil Suitability Study and Nitrate Loading Study for this project and for all projects where exceedance of nitrate loading standards may occur. These Studies were completed by Live Oak GeoEnvironmental, Inc. (Project No. 2109), dated February 23,2021. The EHD Findings/Directive Letter was dated March 2, 2021 under Service Request SR0083332. The findings from the Soil Suitability and Nitrate Loading Studies indicate: 1.) The soil underlying the property possesses a rapid percolation rate of 4.39 minutes per inch(min/inch)that requires a civil engineering design for the Onsite Wastewater Treatment System(OWTS), and 2.) The calculated nitrate loading from this project exceeds the standards and must also be mitigated by a civil engineer designed system, both as promulgated by the EHD. The rapid perc rate test result stipulates a separation distance of 20 ft between the floor of the effluent disposal system and the highest anticipated depth to groundwater, as referenced in Section 1.10.2(e)of the SJC OWTS Standards. From the data interpreted by Live Oak, the water table depth under the property is estimated to be 15 ft to 18 ft,thus encroaching upon this 20 ft separation distance. The Nitrate Loading Study calculations found the resultant nitrate-nitrogen effluent concentration to be 13.90 ppm nitrate-nitrogen(NO3-N),which is 3.90 ppm(39%) over the Maximum Contaminant Level (MCL) of 10 ppm NO3-N. This report addresses both issues of rapid soil permeability and excess nitrate loading, and provides EHD with the discovery of natural attenuation of soil permeability, and an engineered design resolution to mitigate nitrate loading by an innovative effluent equal distribution system. Applicable Section(§)numbers of the San Joaquin County EHD Onsite Wastewater Treatment System Standards for an engineered system(Section 7, et al)are noted within this document. MATERIALS AND METHODS Having conducted numerous shallow and deep soil investigative and test procedures in this locale, I was aware of the potential for the existence of hardpan strata. Hardpan strata will naturally create the retardation of rapid soil permeability/percolation conditions referenced in this report, thus meeting the 8 ft separation distance between the floor of the dispersal system and the water table. Page-1- Chesney Consulting