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INTRODUCTION Mr. David Pinnell is proposing to install a modular (manufactured) two bedroom home on property he owns, referenced on the Title Page. This proposed modular home will be considered the primary 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., dated July 7, 2021. The EHD Findings/Directive Letter was dated July 19, 2021 under Service Request SR0083938. The findings from the Soil Suitability and Nitrate Loading Studies indicate that the soil underlying the property possesses a rapid percolation rate of 1.98 minutes per inch (min/inch). The EHD Directive Letter states that "At this (perc) rate, a 20 foot soil separation shall be required between the bottom of the leach field and groundwater for future septic systems. Groundwater at the site was encountered at 10.33 ft below ground surface." To mitigate this rapid permeability, Table 1.10.2 of the SJC Onsite Wastewater Treatment System (OWTS) Standards states that this minimum depth can be "mitigated by system design or enhancement." The EHD requires that a civil engineer investigate the soil characteristics to mitigate rapid permeability, or design for the enhancement to mitigate excessive permeability. This report addresses the issue of rapid soil permeability through investigation and provides EHD with the discovery of natural attenuation of perc-test-measured excessive soil permeability. MATERIALS AND METHODS The perc test conducted by Live Oak was performed at a depth of 2.17 ft below grade, which as indicated below, was conducted in a loamy sand, thus the rapid perc rate. Although a deep boring was drilled down to the groundwater by Live Oak, soil characteristics apparently were not logged. On February 11, 2022, I conducted soil drilling and sampling at the depths referenced below in Table 1 near the southern property line where the effluent disposal field is proposed to be installed. TABLE 1 SAMPLED SOIL CHARACTERISTICS AND ANALYTICAL TEST RESULTS COMPOSITE SAMPLE DEPTHS (SAMPLE ID) SAND, SILT AND CLAY PERCENTAGES SOIL CLASSIFICATION HYDRAULIC SOIL GROUP 0- 1 2" 28%, 36%, 36% yj.,oain Group D 10-36" 80%, 12%, 8% Loamy Sand Group A 48-54" 34%, 58%, 8% Silt Loam Group B Page -1- Chesney Consulting