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02 March 2020 AdvancedGeo Project No. 20-5001 AnEmployee-Owned Company Page 9 of 14 -� 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 Jacktone clay having 0 to 2 percent slopes (#180). The Jacktone clay land complex is composed of alluvium derived from mixed rock sources. Soils are described as somewhat poorly drained; with a very low permeability; and salinity of less than 2.0 millimhos per centimeter (mmhos/cm). The Jacktone clay complex typically have the same chemical properties between surface grade and 37 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 low water storage. These soils will allow low 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. 8.0. GROUNDWATER ANALYSIS There is currently no potable water source supplied to the subject property. A domestic water well is planned to be installed to the east of the proposed residence and will provide potable water to the residence and property. 8.1. DESCRIPTION OF LOCAL GROUNDWATER According to the San Joaquin County Flood Control and Water Conservation District's Lines of Equal Depth to Groundwater Fall 2018 and the DWR Water Data Library, depth to groundwater at the site is approximately 75 feet bsg. Between 2011 and 2018, depth to groundwater at the site has fluctuated between 75 and 85 feet bsg. Groundwater flow direction locally appears to be toward the west-southwest. Groundwater was not encountered in the 42-inch deep percolation test hole advanced on 06 February 2020. 8.2. EXISTING OR POTENTIAL GROUNDWATER CONTAMINATION The immediately adjacent and outlying land use for the parcel is residential and commercial. Potential groundwater contamination can occur from several sources including leaking underground storage tanks, septic systems, agricultural activities, dairies, and stormwater infiltration.