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July 31, 2023 BGG No. G130.09D Soil Depth USCS Percent Percent LL PI Notes Series (inches) Soil Tye Gravel Fines Dams 0-26 SM—silty sand 0 27 -31 0- 18 NP to — Y sand 26-60 SP-SM—Sand to 0 6- 10 0- 14 NP — Silty Sand Veritas SC-SM, SM— NP to _ fine 0-54 Clayey Sand to 0 35 -50 20-30 10 sandy Silty Sand loam 54-70 Cemented n/a n/a 0 NP Hardpan Note:Fines=Silt-sized and Clay-sized particles;LL=Liquid Limit;PI=Plasticity Index Soil Boring On July 13, 2023,we performed a percolation test near the area of the proposed septic system leach field,as shown on Plate 2,Site Plan. Percolation testing was performed in accordance with current San Joaquin County Environmental Health Department percolating testing procedures; a permit was obtained prior to testing and a SJCEHD inspector was present for the final 30 minutes of the test to verify the procedures followed and the rate obtained. The results of the percolation testing and a record of the SJCEHD permit obtained are contained in Appendix A. To prepare for the percolation test, on July 12, 2023, a shallow boring was drilled to a depth of approximately 42-inches below the ground surface(bgs),in the location shown on Plate 2,Site Plan. The boring was manually drilled using a gas-powered man auger. The soils encountered in the shallow boring were visually classified in the field and a log was recorded. The boring log,showing soil classifications and descriptions, is contained in Appendix D. Based upon our field exploration, the general soil profile at the site can be characterized as a sequence of predominantly sandy soils.The upper 42-inches of soil consisted of tan-brown,medium dense,silty sand. More detailed descriptions of the materials encountered in the boring are included in the log in Appendix D. Discussion of Soil Lithology Based on the soil observed in the percolation boring hole, there appears to be potential for percolation. Sandy soils generally have greater potential for percolation than fine-grained(silts and clays) and cemented soils. Percolation testing is discussed in the following section. SOIL PERCOLATION Percolation Testing Procedure Field percolation testing has been performed at the site in accordance with current SJCEHD percolation testing procedures.On July 13,2023,we performed a percolation test in the area of the proposed septic system leach field,as shown on Plate 2,Site Plan. 24-hours prior to testing,a manually powered auger was used to drill a 6-inch-diameter boring to a depth of approximately 42-inches bgs. The soils encountered were classified and logged,and approximately 2-inches of clean sand was placed in the bottom of the borehole. About 18-inches (vertically) of water was poured into the borehole and allowed to saturate overnight. Upon returning to the test hole on July 13,2023,it was observed that BAEZ GEOTECHNICAL GROUP Soil Suitability Study&Nitrate Loading Study-Becerra Residence,18163 S.Carrolton Road Page 4