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April 6, 2022 BGG No. G130.09C Soil Boring On March 10, 2022,we performed a percolation test near the area of the 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 60 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. For the percolation test,on March 9,2022 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 classification 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 6-inches of soil consisted of brown, loose, silty sand. Below the surface soil layer we encountered about 3 feet of brown,medium dense, silty sand to sand with silt. More detailed information of 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 March 10, 2022, 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 March 10, 2022, it was observed that no water remained in the hole. As such, percolation testing was then performed by pouring approximately 6-inches of water into the test hole and measuring the drop in the water level over a single 30-minute interval.No water remained in the hole at the end of the initial 30-minute interval; hence percolation testing continued by pouring approximately 6-inches of water into the test hole and measuring the drop in the water level at 10-minute intervals for a period of one hour, refilling with water as needed. The results of the percolation test are contained in Appendix A. Percolation Test Results A rate of 6.67 minutes/inch was recorded for the proposed septic system and leach field. SJCEHD defines a shallow percolation test hole as having a depth between 36 and 42 inches; a satisfactory percolation rate for a shallow test is one resulting in a water level drop greater than or equal to 1 minute per inch(min/in)but less than or equal to 60 min/in. For the site to utilize a standard septic BAEZ GEOTECHNICAL GROUP Soil Suitability Study and Nitrate Loading Study-Enriquez Residence,17650 Austin Road Page 4