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Nitrate Loading Analysis BSK Job E21-002-01B 2482 Carpenter Road July 13, 2021 Stockton, California P a g e | 3 2. CHEMICAL AND PHYSICAL PROPERTIES OF SOIL BSK performed drilling at the site on February 1, 2021 and percolation tests on February 2, 2021. The Limited Geotechnical Investigation Report Letter Cascade BESS Project includes the soils and geotechnical report with maps of boring locations, boring logs, and analytical results. Below is a summary of findings: • B-1 through B-3: Generally, the borings were slightly moist sandy clays to silty clays • B-1 and B-2: Water content ranged between 13.0% to 26.3% • Hydraulic Conductivity for B-1 at 10.5 feet below ground surface (bgs) was 1.8E-06 centimeters per second (cm/s) • Hydraulic Conductivity for B-2 at 16 feet bgs was 8.7E-08 cm/s • Hydraulic Conductivity for B-2 at 31 feet bgs was 2.6E-08 cm/s • Hydraulic Conductivity for B-3 at 11 feet bgs was 7.0E-05 cm/s • Hydraulic Conductivity for B-3 at 21 feet bgs was 1.2E-08 cm/s • PT-1: Percolation rate of 10 minutes/inch • PT-2: Percolation rate of 25 minutes/inch • PT-3: Percolation Rate of 2 minutes/inch Chemical properties of the soil were not identified outside analytical testing parameters. The soil at the site is generally silty to sandy clay with low hydraulic conductivity in a semi-arid environment. Based on this information and comparisons to other semiarid regions with sandy clay soil, the transport of contaminants like nitrate would be lower than that of soils with higher sand content, higher rainfall and/or soil saturation, or more permeability. 3. GROUNDWATER ANALYSIS 3.1 Description of Groundwater Based on Publicly Available Groundwater Data The depth to groundwater at this Site is not specifically known. Groundwater data used in this analysis was based on publicly available historical data from the nearest groundwater monitoring well (379146N1212401W001), which is located 2,740 ft to the south of the Site. As of August 26, 2020, the depth to groundwater at that location was 44.0 ft bgs (Figure 2). Historic data from nearby wells would indicate that the depth to groundwater at the site would be between 40-50 feet bgs with the groundwater directional flow trending in a east-northeast direction. Seasonal changes between fall 2019 and spring 2020 generally show an approximate fluctuation of less than two feet.