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23 October 2020 AdvancedGeo <br /> Project No. 20-6169 AnEmployee-Owned Company <br /> Page 9 of 15 <br /> calculate the percolation rate. The use of the existing and proposed septic systems should <br /> follow the San Joaquin County On-site Wastewater Treatment Standards. <br /> 7.0. CHEMICAL AND PHYSICAL PROPERTIES OF SOIL <br /> Soil chemical properties were supplied by regionally sourced material for the surrounding <br /> area. <br /> 7.1 . CHEMICAL AND PHYSICAL PROPERTIES OF SITE SOILS <br /> The dominant soil composition in the general area of the property was inferred from <br /> information provided by the United States Department of Agriculture's Soil Geographic <br /> Database (USDASGD). The USDASGD soil survey indicates the soil type for the <br /> property, and the area of the proposed septic disposal field, is predominantly composed <br /> of Tokay fine sandy loam having 0 to 2 percent slopes (#256). The Tokay fine sandy loam <br /> is composed of alluvium derived from granitic rock sources. Soils are described as well <br /> drained; with high permeability; and salinity of less than 2.0 millimhos per centimeter <br /> (mmhos/cm). Soil in the Tokay fine sandy loam complex typically have a profile of fine <br /> sandy loam to 45 inches and sandy loam from 45 to 60 inches bsg. <br /> 7.2. MASS TRANSPORT PROPERTIES OF UNDERLYING SITE SOILS <br /> The percolation test and dominant soil type at the site indicates that the soils are semi- <br /> permeable to permeable and have moderate water storage. These soils will allow <br /> moderate infiltration of water through the surface soils. The longer the effluent remains <br /> near the surface, the more treatment is enhanced due to natural processes within the soil. <br /> If the permeable soils exist to the depth of the groundwater table, it is possible that surface <br /> contaminants may be transported fairly rapidly. <br /> 8.0. GROUNDWATER ANALYSIS <br /> The subject property is supplied with potable water by the onsite domestic water well <br /> located to the north of the existing residence (Figure 2). A groundwater sample was <br /> collected from the well and analyzed for nitrates as part of this study. <br /> 8.1 . DESCRIPTION OF LOCAL GROUNDWATER <br /> According to the San Joaquin County Flood Control and Water Conservation District's <br /> Lines of Equal Depth to Groundwater Fall 2018 and the DWR SGMA Data Viewer, depth <br /> to groundwater at the site is approximately 120 feet bsg. Between 2011 and 2018, depth <br /> to groundwater at the site has fluctuated between 115 and 130 feet bsg. Groundwater <br />