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r <br /> May 21,2002 <br /> r Job Number: LG02-140 <br /> Page 4 <br /> ` water levels for San Joaquin County.' These maps were used to determine the general depth and <br /> flow direction of regional ground water(Plates 2 through 5). The depth was found to be about <br /> 180 feet in depth flowing generally westward. The gradient ranges between 6.7 to 7.1 feet per <br /> mile based on the ground water elevation map for the area. Table 2 summarizes all the available <br /> ground-water information collected for the site and nearby area. <br /> Table 2. <br /> Summary of Available Ground Water Information. <br /> Date,Description,Source Groundwater Depth Notes <br /> r <br /> March 26,2002,no ground water indicated Not encountered. No ground water found to the <br /> in any of the 25 foot borings,Neil O. maximum drilling depth of 25-feet. <br /> Anderson&Associates,Inc. <br /> Ground water sample tested for DBCP and Unknown. Result,DBCP-non detectable, <br /> Nitrate at neighboring well located at Nitrate-10 mg/L-NO,,(MCL-45 <br /> 28312 Mackville Road on 5/2/02. mg/L-NO,). <br /> Fall 1998,San Joaquin County Ground About 180 feet. Ground water gradient 6.7 ft/mi <br /> Water Map. Plates 2 and 4. flowing southwest. <br /> Spring 1999, San Joaquin County Ground About 180 feet. Ground water gradient 7.1 8/mi <br /> Water Map.Plates 3 and 5. flowing southwest. <br /> A ground-water sample was collected from a neighboring well located t 28312 <br /> Mack` ville d. At the time of sampling, the existing agricultural well was not operating. The <br /> ground-water sample was submitted to Precision Enviro-Tech analytical laboratory for DBCP <br /> ` and nitrate testing. The result of the DBCP test was non detectable. The result of nitrate analysis <br /> was 10 mg/L-NO3. The maximum contaminate limit for nitrate in drinking water is 45 mg/L- <br /> NO3. <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 originates <br /> from agricultural fertilizers, livestock waste, and untreated septic tank waste. Nitrate is mobile <br /> and often accumulates in the shallow ground-water zones. In the early 1900's,natural levels of <br /> ' San Joaquin County Flood Control and Water Conservation District, 1999, Depth to ground-water map <br /> r„ and ground-water elevation map for Spring and Fall 1998. Published bi-annually,scale: 1 inch=2 miles. <br /> oe�s i <br /> :r <br /> r <br />