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30 August 2019 AdvancedGeo AGE Project No. 19-4819 Environmental Page 9 of 15 during the test are included on the Percolation Test Rate Field Sheet provided in Appendix D. 6.6. POTENTIAL PROBLEMS PREDICTED On site soils within the shallow percolation test hole demonstrated adequate percolation rates. Additionally, the existing septic system has been properly operating. 6.7. PERCOLATION TEST FINDINGS The shallow percolation test performed provided a satisfactory percolation test rate. The percolation rate of 50 minutes per inch was calculated from data collected during the 4- hour percolation test; the smallest reading over the 4-hour period was used to calculate the percolation rate. The use of the existing and proposed septic systems should follow the San Joaquin County On-site Wastewater Disposal Standards. 7.0. CHEMICAL AND PHYSICAL PROPERTIES OF SOIL Soil chemical properties were supplied by regionally sourced material for the surrounding area. 7.1. CHEMICAL AND PHYSICAL PROPERTIES OF SITE SOILS The dominant soil composition in the general area of the property was inferred from information provided by the United States Department of Agriculture's Soil Geographic Database (USDASGD). The USDASGD soil survey indicates the soil type for the property is predominantly composed of Capay Clay having 0 to 1 percent slopes (#118). The Capay Clay land complex is composed of clayey alluvium derived from sedimentary rock and is dominated by clay. Soils are described as moderately well drained; with a general permeability of 0.06 to 0.20 inches per hour (in/hr); and salinity of less than 2.0 millimhos per centimeter (mmhos/cm). Clays in the Capay Clay complex typically have the same chemical properties between surface grade and 60 inches bsg. 7.2. MASS TRANSPORT PROPERTIES OF UNDERLYING SITE SOILS The percolation test and dominant soil type at the site indicates that the soils are semi- permeable and have moderate water storage. These soils will allow moderate infiltration of water through the surface soils. The longer the effluent remains near the surface, the more treatment is enhanced due to natural processes within the soil. If the permeable soils exist to the depth of the groundwater table, it is possible that surface contaminants may be transported fairly rapidly.