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Soil Suitability / Nitrate Loading Study 11065 North Alpine Road I Stockton, California r rerracon June 30, 2026 1 Terracon Project No. NA267068 1.6. Percolation Test Information 1.6.1. Percolation Test Locations Refer to Section 1.5.1 and Appendix A, Exhibit 3. 1.6.2. Number of Percolation Tests A total of three percolation tests were conducted on the site to fulfill the requirements of the Soil Suitability Study. The percolation tests (131 at 3.5 feet bgs, B2 at 25 feet bgs, and B3 at 15 feet bgs were conducted and witnessed by Ms. Sastina Thammavongsa, EHD representative. Percolation tests conducted as a part of this Soil Suitability Study are supplemented by percolation testing previously performed by Terracon on the site (Terracon Project No. NA197078). A total of four percolation tests (133 through 136) were conducted on October 31, 2019 and observed by Daria Afonskaia, EHD representative. 1.6.3. Boring Preparation and Pre-saturation The percolation test borings were drilled on June 10, 2026. Approximately two inches of pea gravel was placed in the bottom of the borings. A 2-inch diameter PVC pipe with perforations towards the bottom was installed on top of the gravel and the annular space was backfilled with pea gravel. Pre-saturation of the percolation test holes occurred on June 10, 2026 approximately 24 hours prior to the day of testing. The depth of water used to pre-soak the shallow borings was approximately 1.0 foot above the top of the gravel and 0.5 feet above the top of gravel for the deep borings. 1.6.4. Condition of Borings after Pre-saturation All borings were intact after the 24-hour pre-soak period. Upon arrival to the site on June 11, 2026, Terracon observed water remaining in borings 131, B2, and B3. 1.6.5. Percolation Test Procedure Percolation tests were conducted for the borings on June 11, 2026 in accordance with the requirements of the San Joaquin County EHD. The tests were observed by Ms. Sastina Thammavongsa from the EHD. Measurement of the water level during the percolation tests was from a fixed reference point on the PVC casing using a calibrated Solinst electric water level detector with a depth accuracy of 0.01 feet. All tabulated values on the field data sheet (Appendix E) are in decimal feet. After water infiltration was observed, the holes were checked and refilled as necessary to maintain approximately 0.5 feet (6 inches) of water above the top of gravel. Terracon observed water remaining in test borings 131, B2, and B3 and utilized Procedure #1 of the Facilities I Environmental I Geotechnical I Materials 12