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INTRODUCTION Mr. Todd Roddan is the Contractor for this project and is in the process of constructing an Accessory Dwelling Unit (ADU) on the subject property referenced on the Title Page. The new, two-bedroom structure is considered an ADU by San Joaquin County since there is an existing Single Family Residence (SFR) structure on the property. Additionally, as illustrated on the attached Site Plans, there is an existing structure at the north end of the property, referenced as a game room. The San Joaquin County Environmental Health Department (EHD) required a Soil Suitability Study and Nitrate Loading Study for this project under San Joaquin County Development Title, Section 9- 1105.2(d). These Studies were completed by LiveOak GeoEnvironmental, Inc. (Project No. 2204), dated February 8, 2022 (SR0084964). The Nitrate Loading Study calculations by LiveOak found the resultant nitrate -nitrogen effluent concentration to be 15.4 ppm nitrate -nitrogen (NO3-N), which is 5.4 ppm over the Maximum Contaminant Level (MCL) of 10 ppm NO3-N. The findings from the LiveOak Studies indicate that: 1.) The shallow soils underlying the property possesses an acceptable percolation rate of 7.5 min/inch, and 2.) The calculated nitrate loading from this project exceeds the standards and must be mitigated by a California Registered Civil Engineer, pursuant to the EHD Directive Letter. Mitigation of the nitrate loading may be completed by a review of the nitrate loading parameters and calculations, a specific design of an onsite wastewater treatment system (OWTS), or another method deemed reliable by the engineer. This report addresses three issues to mitigate of future nitrate loading from the project: Leachfield soil physical and chemical characteristics, recalculating the nitrate loading equation .using different parameters, and stipulating the installation of a 1,600 gallon septic tank in lieu of a 1,200 gallon tank. MATERIALS AND METHODS The first nitrate loading investigative procedure was to address percolation at a depth of 12 ft. Although an EHD perc permit was obtained (SR0085889) for this deep test depth, it was not witnessed by an EHD sanitarian since the shallow perc test at 2.79 ft conducted by LiveOak was witnessed and approved by EHD. This deeper test boring was drilled by a B24 Drill Rig. TABLE 1 PERCOLATION TEST RESULTS WITH CORRESPONDING APPLICATION RATES IN GALLONS / FV / DAY DEEP 12 FT TEST BORING I 125.0 min/inch / 0.100 gallons/ft'-/day In addition to measuring the permeability of the deeper soils through percolation testing, three soil samples were retrieved from the exploratory test boring for chemical characteristics and particle size analyses (soil texture) of the native soil. This information is found below in Table 2: Page -1- Chesney Consulting