SR0083212_SSNL - Laserfiche WebLink

Home Browse Search

January 21, 2021 BGG Job No. G130.09 the upper 2%2 feet, with the hardpan reported to be near impermeable. The Web Soil Survey report is contained in Appendix C. Soil Boring On October 9, 2020, we performed a percolation test in 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 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. For the purpose of the percolation test, on October 8, 2020 a shallow boring was drilled to a depth of about 3'/2 -feet below the ground surface (bgs), in the approximate 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 explorations, the general soil profile at the site can be characterized as a sequence of predominantly clayey soils. The upper foot of soil consists of brown, hard, silty clay with sand. Below the surface soil layer we encountered about 2'/2 feet of gray -brown, hard, silty clay. 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 some potential for percolation. Fine-grained (silts and clays) and cemented soils generally have lower potential for percolation than sandy 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 October 9, 2020, 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 3'/2 feet bgs. The soils encountered were classified and logged, and approximately 2 -inches of clean pea gravel was placed in the bottom of the boring. About 18 -inches (vertically) of water was poured into the borehole and allowed to saturate overnight. Upon returning to the test hole on October 9, 2020, it was observed that 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. The results of the percolation test are contained in Appendix A. Percolation Test Results A rate of 20.0 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 BAEZ GEOTECHNICAL GROUP Soil Suitability Study and Nitrate Loading Study - Valdovinos Residence Page