SR0080932 SSNL - Laserfiche WebLink

Home Browse Search

DBCP is a nematocide and soil fumigant for vegetables and grapes. It is known to cause male reproductive effects and is classified as a probable human carcinogen. Most domestic use of DBCP was discontinued in 1977 through 1979. The US EPA set the MCL at 0.2 parts per billion (ppb, equivalent to ug/L) because it believes that given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. The Maximum Contaminant Level Goal (MCLG) for DBCP is zero. Soil Profile and Geologic Information The Site is depicted on the Preliminary geologic map of the Tracy quadrangle, San Joaquin County, California (Diblee, 1981). The Site is depicted within a map unit of Holocene alluvium (Plate 8). The surface and near surface soils located at the Site are reported by the USDA Web Soil Survey to be composed of Stomar clay loam (Plate 9) (USDA, 2019). The table below presents some selected properties of this soil: Table 1. Selected Properties of On-Site Soils (USDA, 1992) Soil Name Depth Unified Soil Salinity Soil Perme- Septic tank and Map (in) Class Reaction ability absorption Symbol Classification mmhos/cm pH (in/hr) fields Stomar clay 0-17 Clay loam; CL <2 6.6-7.3 0.2-0.6 Severe: loam, 0-2% 17-47 Clay loam, clay; CL, CH <2 6.6-8.4 0.06-0.2 peres slowly slopes, 252 47-60 Clay loam, silty clay <2 7.4-8.4 0.2-0.6 loam, CL 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 June 21, 2019, Live Oak excavated a shallow soil boring near the proposed septic disposal area of the Site for the purpose of conducting a percolation test. The boring was four inches in diameter, 3.13 feet deep, and was excavated by hand auger (Table 2). The location of the boring is indicated on Plate 10. The soil in the boring was similar to that described by the Soil Survey. Clayey silt was encountered to the full depth of the hole. The soil log is presented on Plate 11. Discussion of Soil Lithology Based on the soil observed in the boring, there appears to be moderate potential for percolation in the shallow soil zone. Sandy soils generally have a much greater potential for percolation than fine-grained or cemented soils. However, a percolation LOGE 1922 Page 5