SU0010715 SSNL - Laserfiche WebLink

Home Browse Search

Soil Profile and Geologic Information The Site is mapped on the Geologic Map of California: San Jose sheet (Rogers, 1966). It is depicted within a map unit of Pleistocene nonmarine deposits (Plate 7). The surface and near surface soil located at the Site is reported by the Web Soil Survey (USDA, 2016) to be composed of San Joaquin sandy loam (Plate 8). The table below presents some selected properties of this soil type: Table 1. Selected Properties of On-Site Soil (USDA, 1992) Soil Name Depth Unified Soil Salinity Soil Perme- Septic tank and Map (in) Classification mmhos/cm Reaction ability absorption Symbol pH (in/hr) fields San 0-13: Sandy loam, SM <2 5.6 -6.5 0.6 - 2.0 Severe: Joaquin 13-20: Clay loam, clay, CL <2 6.1 - 7.8 <0.06 cemented sandy loam, 20-60: Indurated --- ___ ___ p �eres 0-2 percent slow) slopes, 236. Note:The table descriptions do not necessarily reflect site-specific soil properties. See description of the map unit for composition and behavior characteristics of the map unit. Soil Borings On April 25 through May 2, 2016, Live Oak excavated shallow and deep soil borings on each proposed parcel of the Site for the purpose of conducting percolation tests. The borings were four inches in diameter, 3.25 to 14.35 feet deep, and were excavated by hand auger (Table 2). The locations of the borings are indicated on Plate 9. The soil in the borings was similar to that described by the Soil Survey. At all locations, sandy silt was encountered to a depth of approximately 1.5 feet, followed by sandy clay to approximately 2.5 feet, followed by a hardpan of cemented sandy silt to approximately 4.0 feet, followed by very fine sand. At locations P1, P2 and P4, fine to medium sand was encountered at depths of 11.5, 13.0, and 10.0 feet, respectively. At location P3, gravelly, fine to coarse silty sand was encountered at a depth of 6.5 feet. The soil logs are presented on Plates 10 through 13. Discussion of Soil Lithology Based on the soil observed in the borings, there appears to be limited potential for percolation in the shallow soil zones and good potential for percolation in the deeper soil zones at all the test locations. Sandy soils generally have a much greater potential for percolation than fine-grained or cemented soils. However, a percolation test is the only accepted method for determining the suitability of the soils for a septic disposal area. Percolation test results are discussed in the following section. LOGE 1602 Page 5