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30 June 2022 AdvancedGeo <br /> Project No. 22-6900 AnEmp/oyee-O—edCompany <br /> Page 9 of 15 '.MI <br /> four-hour percolation test; the final reading over the four-hour period was used to <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 property <br /> is predominantly composed of San Joaquin sandy loam having 0 to 2 percent slopes <br /> (#236). The San Joaquin sandy loam is composed of alluvium derived from granitic rock <br /> sources. Soils are described as moderately well drained, with very high runoff, and salinity <br /> ranging from 0.0 to 2.0 millimhos per centimeter (mmhos/cm). The San Joaquin sandy <br /> loam typically features sandy loam from 0 to 13 inches bsg; clay from 13 to 20 inches <br /> bsg; and indurated soils from 20 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 and have moderate water storage. These soils will allow moderate infiltration <br /> of water through the surface soils. The longer the effluent remains near the surface, the <br /> more treatment is enhanced due to natural processes within the soil. If the permeable <br /> soils exist to the depth of the groundwater table, it is possible that surface contaminants <br /> 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 southeast 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 DWR SGMA Data Viewer for Spring 2021, depth to groundwater at the <br /> site is approximately 150 to 160 feet bsg. Between 2011 and 2021, depth to groundwater <br /> at the site has fluctuated between 130 and 160 feet bsg. Groundwater flow direction <br />