Laserfiche WebLink
contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in <br /> shallow ground water zones. Based on work in the Sacramento Valley from the early <br /> 1900s, it is estimated that under "natural" conditions, ground water contains nitrate at <br /> concentrations no more then about 3 mg/L-N. Nitrate may be increasing in areas with <br /> concentrations of 5.5 mg/L-N or more (Hull, 1984). The US EPA has set the Maximum <br /> Contaminant Level (MCL) for nitrate at 10 mg/L-N. <br /> Although nitrate is a naturally-occurring compound necessary for plant growth, it can <br /> cause health problems when present at high levels in drinking water. The most <br /> common health effect of nitrates in water is methemoglobinemia, or blue baby <br /> syndrome, which results in reduced oxygen supply to vital tissues. Pregnant women <br /> and certain others can also develop methemoglobinemia. Symptoms include a bluish <br /> color of the skin, as well as headache, dizziness, weakness, and difficulty breathing. <br /> Ingestion of high levels of nitrates over time can also lead to gastric problems. <br /> DBCP is a nematocide and soil fumigant for vegetables and grapes. It is known to <br /> cause male reproductive effects and is classified as a probable human carcinogen. <br /> Most domestic use of DBCP was discontinued in 1977 through 1979. The US EPA set <br /> the MCL at 0.2 parts per billion (ppb, equivalent to ug/L) because it believes that given <br /> present technology and resources, this is the lowest level to which water systems can <br /> reasonably be required to remove this contaminant should it occur in drinking water. <br /> The Maximum Contaminant Level Goal (MCLG) for DBCP is zero. <br /> Soil Profile and Geolo�c is Information <br /> The Site is mapped on the Preliminary geologic map of Cenozoic deposits of the Bellota <br /> quadrangle, California (Marchand, D.E., and Bartow, J.A., 1979). It is depicted within a <br /> map unit of the Modesto formation upper member, defined as "foothill-derived alluvial <br /> silt, clay and minor sand forming terraces, upper fans, and following distributaries <br /> across lower fans; abundant volcanic detritus" (Plate 10). <br /> The surface and near surface soils located at the Site are reported by the USDA Web <br /> Soil Survey to be composed of Boggiano clay loam (Plate 11) (USDA, 2019). The table <br /> below presents some selected properties of this soil: <br /> LOGE 1942 Page 5 <br />