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20 November 2020 Advancedt ieo Project No. 20-6205 AnEmp/oyee-OwneCCompony 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, and the area of the proposed septic disposal field, is predominantly composed of the Galt-Urban land complex having 0 to 1 percent slopes (#162). The Galt-Urban land complex is composed of clayey alluvium derived from igneous, metamorphic, and sedimentary rock over cemented alluvium derived from igneous, metamorphic and sedimentary rock. Soils are described as moderately well drained; with moderately low permeability; and are non-saline (less than 0.5 millimhos per centimeter; mmhos/cm). Soil in the Galt-Urban land complex typically have a profile of clay to 32 inches and cemented material from 32 to 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 slow to 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. 8.0. GROUNDWATER ANALYSIS The subject property will be supplied with potable water by the onsite domestic water well (Figure 2). A groundwater sample was not collected from the well as part of this study because there is no electrical power to the site. 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 SGMA Data Viewer, depth to groundwater at the site is approximately 40 feet bsg. Between 2011 and 2018, depth to groundwater at the site has fluctuated between 40 and 60 feet bsg. Groundwater flow direction locally appears to be to the west-southwest. 8.2. EXISTING OR POTENTIAL GROUNDWATER CONTAMINATION The immediately adjacent and outlying land use for the parcel is residential. Potential groundwater contamination can occur from several sources including leaking