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June 11,2003 <br /> Job Number:LG03-137 <br /> Page 4 <br /> Two water samples were collected..from the on-site water well on June 3, 2003 by Dave Welch'of <br /> our office. The water samples were obtained from the on-site hose. The water samples were . <br /> F-1 delivered to Precision Enviro-Tech, Stockton, for analytical testing'on June 4, 2003., Each of the <br /> samples were tested for nitrate and the presence of coliform. <br /> The result of the analytical test indicates that nitrate as nitrogen was found at.76 mgfL7NO3 (or <br /> 1.6 m - for the domestic well. The result of the nitrate test indicates the ground water is <br /> r above the maximum contaminate level set by the United States Environmental Protection <br /> l - L Agency of 45 mg/L-NO3 (or 10 mg/L-N). The presence of coliform was not indicated. <br /> The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin <br /> County-and.other parts of the Central Valley. Nitrate in groundwater occurs as a result of the <br /> application of fertilizers, livestock waste;and untreated septic tank waste. Nitrate is mobile and <br /> often accumulates in the,shallow ground water zones. <br /> In the early 1900's, natural levels of nitrate in ground water were measured in forty-three(43) <br /> wells throughout the Sacramento Valley by Bryan (1923). It was thought that ground water at <br /> that time was close to "natural"conditions. Based on the work by Bryan,.it is estimated that . <br /> under"natural"conditions,ground water concentration containing nitrate is no more then about <br /> F. 13.5 NO3 (3:mg/L-N)..Areas having 24.75 mg/L NO3 (5.5 mg/L=N) or more are those in which <br /> nitrate concentrations may be increasing(Hull,.1984). <br /> 5.0 GEOLOGY, SOILS,AND PERCOLATION TEST <br /> 'The surface geology at the site is shown on Dibblee's (198 1) map and is composed of Holocene <br /> F• alluvium(Plate 2). Alluvium is typically composed of mixtures of sand, silt,and clay derived <br /> from fluvial processes. <br /> The surface and near surface soils located at site are reported io be composed of the Capay ,clay, <br /> E r Capay-Urban land complex, and the Stomar clay loam (Plate 3) (USDA, 1993). Table 3 presents <br /> 4 , some selected properties of.the three soil types located on the property. <br /> x w <br />