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L <br /> ]I <br /> UM <br /> Mr.Jeffrey Wong <br /> San Joaquin Public Health Service <br /> First Quarter 2004 Groundwater Monitoring Report f <br /> June 11,2004 <br /> Page 3 of 4 F <br /> a <br /> The results of the data validation are included in the Data Validation Summary (Appendix B). The data <br /> validation found all results to be acceptable and useable for their intended purpose with the no <br /> limitations: <br /> 1 GROUNDWATER ELEVATIONS AND GRADIENT <br /> A contour map of groundwater elevations is shown in Figure 3. Current and historical water level <br /> elevation data for all wells are included in Table 2. Water levels measured in the first quarter of 2004 <br /> were between 44 and 46 feet below ground surface, or approximately —30 feet with reference to mean <br /> 1 L sea level datum(MSLD). Although historical data indicate a rise in water levels subsequent to 1990, data <br /> collected since December 1999 suggest that this trend may have stabilized or reversed, <br /> First quarter 2004 water level data indicate a groundwater gradient of 0.011 to the northwest. <br /> GROUNDWATER ANALYTICAL RESULTS <br /> a <br /> Li <br /> A historical summary of analytical results for groundwater samples collected through March 2004 is <br /> included in Table 3. Results for tetrachloroethene (PCE) and 1,2-dichloroethatne (1,2-DCA) are also <br /> presented on Figure 4. <br /> I' <br /> TPH-diesel } <br /> Neither total petroleum hydrocarbon (TPH) reported as diesel or unknown hydrocarbon (UH) were <br /> �4. identified in groundwater samples collected during this quarter. <br /> Volatiles and Oxygenates by EPA Method 8260B <br /> 1,2-Dichloroethane.was reported in samples collected from DMW-5 (3.1 micrograms per liter (gg/L)), <br /> L DMW-6 (23 gg/L), and DMW-9 (31 99/14 With the exception of DMW-9, which, together with DMW- <br /> t <br /> 8 was sampled for the first time this quarter, these results are lower than most previously reported results <br /> for those wells. Chloroform was reported in samples collected from DMW-1 (2.0 gg/L), DMW-5 (1.7 <br /> gg/L), and DMW-8 (1.0 gg/L). PCE was reported in the sample collected from one well, DMW-8, and a <br /> concentration of 3.9 gg/L. Carbon tetrachloride was reported in samples collected from DMW-5 (1.1 <br /> gg/L) and DMW-8 (1.3 gg/L). Toluene was reported in the sample collected from DMW-9 (1S gg/L). <br /> SUMMARY <br /> LThe following summarizes the results of March 2004 groundwater monitoring. <br /> _ ► Groundwater elevations measured during March 2004 were approximately--30 feet MSLD,and with a <br /> gradient of 0.011 to the northwest. <br /> • TPH was not Y samP reported in an of the' les. <br /> p <br /> L� <br /> i. KAWprocess%227361new1Q04AFP revOlAm <br /> { <br /> r <br />