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LOGE 19-21: Ng SSNLS Addendum Page 2 <br /> June 2, 2020 <br /> cemented silty sand with clay to the full depth of the hole. A percolation rate of 22.7 min/in <br /> was obtained in the four-hour test. <br /> After completion of the second percolation test, Mr. Ng again revised the site map, returning <br /> the proposed leach field to the original location southeast of the house. It should be noted that <br /> both test locations are within 100 feet of both proposed leach field areas. <br /> A site map indicating both test locations is attached (Plate 1), as well as a cross-section <br /> depicting the depths of the tests relative to each other (Plate 2). It appears that, due to <br /> importation of 12 to 14 inches of fill in the area, the new percolation test was conducted <br /> primarily in the upper (native), silt/clay soil stratum, while the 2019 percolation test was <br /> conducted in the subsurface layer of slightly cemented silty sand. Photographs of the soils <br /> encountered on both dates are included for reference. The surface layer from the 2019 test <br /> appears to be substantially similar to the subsurface layer from the 2020 test; some variations <br /> in clay content may exist within this layer. <br /> Based on the results of the two percolation tests and comparison of the soil types, it appears <br /> that the slower percolation rate observed in 2020 is due in part to its shallower depth relative to <br /> the native soil. Additionally, it should be remembered that soils are not homogeneous, and it is <br /> common for soil layers to exhibit variations. Compaction due to grading activities may also <br /> have altered the characteristics of the soils in the area. For these reasons, it is the opinion of <br /> Live Oak that the average of the two test rates, 13.7 min/in, may be the best representation of <br /> current soil conditions in the septic leach field area. <br /> We appreciate your comments regarding this project. Please don't hesitate to call if we can be <br /> of further service. <br /> Sincerely, <br /> Live Oak GeoEnvironmental, Inc. <br /> NAL <br /> Abigail <br /> Abigail acco, Project Manager DAVID J.VXKCH <br /> N0.2151 �. <br /> CERFG1EU <br /> ENGINEF AG <br /> .\\/ GEOIln. <br /> Davi3 J. Welch, CEG, CHG, PGP \SCA <br /> Attachments: Plate 1. Percolation Test Locations <br /> Plate 2. Cross Section of Percolation Test Area <br /> CC: Matthew Ng <br /> 16797 S. Austin Rd. <br /> Manteca, CA 9533 <br />