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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 Geologic Information <br /> The Site is depicted on the Preliminary geologic map of Cenozoic deposits of the <br /> Bellota quadrangle, California (Marchand and Bartow, 1979). The Site is depicted <br /> within a map unit of the Riverbank formation upper member described as "arkosic <br /> alluvium forming Mokelumne River terraces and alluvial fan; chiefly sand; probably <br /> glacial outwash" (Plate 11). <br /> The surface and near surface soils located at the Site are reported by the USDA Web <br /> Soil Survey to be composed of San Joaquin loam, thick surface, with a small portion of <br /> Hollenbeck silty clay on the southern side of the Site (Plate 12) (USDA, 2020). The <br /> table below presents some selected properties of these soils: <br /> LOGE 20-20 Page 5 <br />