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Mr Barton ' 06/27/2006 Page 3 of 5 ' During the quarterly monitoring event, groundwater elevations ranged from 26 68 feet (MW-8) to 23 80 feet (MW-5) below mean sea level at the site Since the first quarter of 2006, groundwater elevations have increased an average of 128 feet at the site The groundwater flow direction was generally to the ' east-southeast as shown on the potentiometne map (Figure 1) and the horizontal hydraulic gradient was calculated at approximately 0 017 foot per foot (ft/ft) The predominant groundwater flow direction has been towards the east-southeast at the site, as depicted on the groundwater flow direction rose diagram ' (Attachment 2) Analytical Results ' Analytical results for the quarterly groundwater monitoring event are presented in Attachment 1 —Tables 1 through 4 Figure 2 presents an isoconcentration map for PCE Results for groundwater samples are ' summarized in the table below Frequency Range of of California ' Detected Frequency of Concentration of Constituent Detection Primary Concentrations s Exceedances Exceedances(ug/]L) Above the (ug(L)2 MCL MDL Benzene 1113 0 5 1 011 ' 2 TCE 8/13 2-23 5 418 3(MW-6), 8(MW-3),8 (MW-7), 6 MW-110 5,200(MW-6),4,100(MW-7), ' • 3,200(MW-3), 590 (MW-2), PCB 12/13 2-5,200 5 11112 540(MW-13), 340(MW-5),170(MW-4), 120(MW-11D), ' 110(MW-14), 76(MW-9), 41 MW-10 Notes 1 MDL=method detection hnut 2 ug/L=nucrograms per liter,equivalent to parts per billion 3 MCL =maximum contaminant level Detected concentrations of benzene, TCE, and PCE are consistent with detected concentrations from the first quarter of 2006 TPH and MTBE were not detected above method detection limits (MDLs) in groundwater samples BTEX compounds were not detected above MDLs with the exception of one detection of benzene Benzene was detected below the California Primary MCL in monitoring well MW- 11D at a concentration of 0 5 µg/L As shown in the table above, TCE and PCE were detected in eight wells and twelve wells, respectively As discussed in the Fourth Quarter 2005 Groundwater Monitoring Report (SECOR, 2006), detections of TCE and PCE are associated with the chlorinated cleaning solvent impacts at Lincoln Village Shopping Center located upgradient of the site Summary and Conclusions The quarterly groundwater monitoring indicates the following • • Results of the second quarterly monitoring event are consistent with results of the first quarterly event for 2006 009603054 doe BLASLAND, BOUCK S LEE, INC an ARCADIS company