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LBA Realty Draft Soil Suitability and Nitrate Loading Study Chapter 2. Chemical and Physical Properties of Soil 2.1. Chemical and Physical Properties of the Soils Underlying the Site Two geotechnical investigations were completed on the site.The first was performed in 2018 and the second in 2020. A soil boring was conducted near the proposed leach fields for Buildings A and B to a depth of 11.5 feet.The boring indicates that soils consist of clay and silty clay. See Attachment 1.A soil boring was conducted near the proposed leach field for Building C to depth of 16.5 feet. The boring indicates that soils consist of Clay and sand. See Attachment 2. Soil chemistry was analyzed in the location of the built up, example leach field.See Attachment 3 for the lab test results.The soil sample was taken at a depth of 3'.Test results indicate the that Nitrates are non- detectable and a neutral pH of 7.5. Natural Resources Conservation Service soil survey indicates the top soils consist of Capay clays with 0-1% slopes. 2.2. Mass Transport Properties of the Soils Underlying the Site Preliminary percolation tests at the site have revealed that the soils are permeable.The soil will allow moderate infiltration of water through the surface soils. Effluent remaining near the ground surface provides more opportunity for biologic processes to occur. In addition, soil borings at the site consistently show the presences of sandy clay lenses to the depth of 50 feet.Although these lenses are unlikely to act as impermeable barriers,they will reduce the rate of infiltration and increase the dispersion of the nitrate. 2.3. Percolation Testing Four(4)shallow percolation tests were conducted at the Site in the area proposed for Building A and Building B. Percolation test procedures conformed to the EHD requirements. Per conversations with the EHD, the percolation tests will be repeated at the locations of the finished grade of all three(3) leach fields.The following results are the basis of design. The completed percolation test forms from the field measurements are included as Attachment 4. Field data provides percolation rates from the holes tested and provides the basis for septic system leach trench design. Results of the percolation tests are summarized in the following table. Table 1—Percolation Test Field Data Summary Test Hole Depth Final Percolation Rate(minutes/inch) Test Duration Results 14" 62.5 4 Hours Fail 28" 50 4 Hours Acceptable 38" 5.95 4 Hours Acceptable 50" 9.26 1 Hour Acceptable November 30, 2020 2-1 Schaaf & Wheeler CONSULTING CIVIL ENGINEERS