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14WO %ftmw <br /> September 20,2001 <br /> Job Number: LGO1-098 <br /> Page 5 <br /> Date,Source Groundwater Depth Notes <br /> Fall 1998, San Joaquin County Flood 26 feet. Gradient: 5.6 feet/mile flowing <br /> Control and Water Conservation District north-northwest. <br /> map.[ Plates 2 and 4. <br /> Sp=5. <br /> ounty Flood 20 feet. Gradient: 6.3 fect/mile flowing norlh <br /> Ction District.[ <br /> Pl <br /> Note:ND—Non-Detectable(or not found at detectable limits). <br /> The depth to ground water at the site, measured in east well, was found to be 34 feet <br /> below the ground surface on August 17, 2001. A water sample was obtained from east well to <br /> detect the presence of dibromochloropropane(DBCP) and Nitrate (NO3) per County <br /> requirements. The access to the well was difficult and the water sample that was finally pulled <br /> from the well was brown to creamy tan colored. The sample was sent to Precision <br /> Environmental Laboratory for testing on the same day. <br /> The test results indicates that DBCP was non-detectable (ND) and nitrate as NO3 was <br /> found at 100,000 ug/1-N. The result of the nitrate test indicates the ground water_is above the <br /> maximum contaminate level (MCL set by the United States Environmental Protection Agency <br /> of 10 mg/L as nitrate N or 1,000 ug/L as nitrate N. This is equivalent to 10 times the MCL for <br /> nitrate of 1000 ug/L as N. The extremely high result may be due to a contaminated well sample, <br /> not reflective of the condition of the aquifer. The well has sat idle for many years. <br /> Due to the questionable nitrate result, a second sample was collected from the fire station �\ <br /> (level <br /> ll located north and across the street from the site. The fire station keeper said the well was <br /> bably shallow and they have water quality problems which require monitoring and the use of <br /> embrane filter. The water sample was collected at the spigot at the well head before the filter. <br /> e resulet is 0.71 mg/L_as Nitrate Nor_71.0 ug/L as Nitrate N. The result of the <br /> ond nitrate test indicates the ground water sample was well below the maximum contaminate <br /> set by the United States Environmental Protection Agency of 10 mg/L as Nitrate N or 1,000 <br /> /L as Nitrate N. <br /> The presence of nitrates and DBCP are not uncommon in shallow ground-water aquifers <br /> in San Joaquin County and other parts of the Central Valley. Nitrate in ground water occurs as a <br /> result of the application of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is <br /> mobile and often accumulates in the shallow ground-water zones. <br /> �pE RSO <br /> Z /~ <br /> O <br /> *SSo� <br />