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increasing in areas with concentrations of 24.75 mg/L-NO3 (5.5 mg/L-N) or more (Hull, • 1984). The US EPA has set the Maximum Contaminant Level (MCL) for nitrate as nitrogen at 10 mg/L-N. Although nitrate is a naturally-occurring compound necessary for plant growth, it can cause health problems when present at high levels in drinking water. The most common health effect of nitrates in water is methemoglobinemia, or blue baby syndrome, which results in reduced oxygen supply to vital tissues. Pregnant women and certain others can also develop methemoglobinemia. Symptoms include a bluish color of the skin, as well as headache, dizziness, weakness, and difficulty breathing. Ingestion of high levels of nitrates over time can also lead to gastric problems. 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 µg/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. The laboratory analytical results are attached as Appendix 5 of this report. • Soil Profile and Geologic _Information The Site is mapped on the Geologic Map of California: San Jose sheet(Rodgers, 1966). It is depicted within map units of Great Valley basin deposits (Plate 9). The surface and near surface soils located at the Site are reported by the Web Soil Survey (USDA, 2015) to be composed of Merritt silty clay loam, Egbert silty clay loam, Grangeville fine sandy loam, and Peltier mucky clay loam (Plate 10). The table below presents some selected properties of these soils: Table 1. Selected Properties of On-Site Soils (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 Egbert silty 0-14 Silty clay loam; CL, ML <2 6.1-7.8 0.2-0.6 Severe: clay loam, 14-40 Silty clay loam, clay <2 6.1-7.8 0.06-0.2 wetness, sandy loam, clay; CL, CH poor filter substratum, 40-60 Stratified loamy fine <2 7.4-7.8 6.0-20 partially sand to sand; SM drained, 0- 2% slopes, 154 • LOGE 1523 Page 5