SU0009423 SSNL - Laserfiche WebLink

Home Browse Search

Water Sample Live Oak collected a water sample from the southern of the two irrigation wells on the ( 3) Site on February 11, 2013. The sample was to be analyzed for nitrate and dibromochloropropane (DBCP) per San Joaquin County Environmental Health Department policy. As required by the laboratory, the sample was collected in a plastic container and two glass vials for nitrate and DBCP analysis, respectively. A trip blank was also utilized for the sample. The sample was placed on ice and transported under chain of custody to FGL Environmental, Stockton. Nitrate was detected in the sample at a concentration of 3.9 mg/L-NO3, well below the US EPA's Maximum Contaminant Level (MCL) of 45 mg/L-NO3 DBCP was not detected in the sample. Nitrate is commonly detected in shallow ground water aquifers of the Central Valley. Application of fertilizers, livestock waste, and untreated septic tank waste can all contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in shallow ground water zones. Based on work in the Sacramento Valley from the early 1900s, it is estimated that under "natural" conditions, ground water contains nitrate at concentrations no more then about 13.5 mg/L-NO3 (3 mg/L-N). Nitrate may be increasing in areas with concentrations of 24.75 mg/L-NO3 (5.5 mg/L-N) or more (Hull, 1984). 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) 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 Cenozoic deposits of the Bellota Quadrangle, California (Marchand and Bartow, 1979). The Site is depicted within map units of the Turlock Lake Formation, Mehrten Formation, and Laguna Formation. The Turlock Lake Formation is described as "arkosic alluvium, probably glacial outwash in part; includes some locally-derived alluvium in areas near the Calaveras River; chiefly sand with some silt and minor gravel." The Mehrten Formation is described as "andesitic conglomerate, sandstone, mudstone, and lahars." The Laguna Formation unit is described as "arkosic gravel, sand, and silt with some LOGE 1217 Page 4