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Ms Victoria McCartney ' 07/28/06 Page 3 of 4 ' Results Groundwater Flow ' Depth-to-water measurements were subtracted from the surveyed top-of-casing elevation to calculate the groundwater elevations for each monitoring well Depth-to-water and the calculated groundwater ' elevations are presented in Table 1 of the G-R Groundwater Monitoring & Sampling Report (Attachment 1) Calculated groundwater elevation data were then used to constrict the groundwater potentiometric map [Figure 1 of the G-R Groundwater Monitoring& Sampling Report, (Attachment 1)] ' Groundwater elevations at the site ranged from 8 72 (MW-1) to 9 13 (MW-2) feet below mean sea level Groundwater elevations across the site have increased an average of 2 42 feet since the first quarter of ' 2006 The groundwater flow direction was generally to the east, as illustrated on the potentiometric map [Figure 1 of the G-R Groundwater Monitoring & Sampling Report, (Attachment 1)] and the horizontal hydraulic gradient was approximately 0 005 foot per foot (ft/ft) The groundwater flow direction at the ' site has been predominately to the northeast since May of 2000 as depicted on the Groundwater Flow Direction Rose Diagram(Attachment 2) Groundwater Analytical Data ' A concentration map for TPH-G, TPH-D, benzene, and MTBE is presented as [Figure 2 of the G-R Groundwater Monitoring & Sampling Report (Attachment 1)] Analytical results for the quarterly ' groundwater monitoring event are presented in Tables 1 through 4 of the G-R Groundwater Monitoring& Sampling Report (Attachment 1) Maximum and minimum concentrations of the petroleum hydrocarbon constituents detected in the groundwater samples are presented in the table below ' Frequency Range of of Detected California Frequency Concentration of Constituent Detection Primary of Concentrations 3 Exceedances in ug/L(Well ID) Above the MDL' m ug/L TPH-G 113 4,500` -- -- -- TPH-D 43/3 60- 1,600 TPH-MO 313 79-350 -- -- __ Benzene 113 480 5 1/1 480 MW-3 MTBE 213 8-4,400 13 112 4,400 MW-2 TBA 1/3 110 ETBE 113 17 -- -- -- TAME 1/3 29- -- -- __ I 1,2-DCA 213 06-2, 0 5 212 2 (MW-2), 0 6 MW-3 Notes 1 MDL_method detection limit 2 ug/L=micrograms per liter,equivalent to parts per billion(ppb) 3 MCL =maximum contaminant level 4 TPH-D and TPH-MO results using silica gel clean-up These concentrations ranges are generally consistent with the concentrations detected during the first quarter of 2006, as summarized in Tables 1 and 3 Methanol, ethanol, DIPE and EDB were not detected • at concentrations above the method detection limits(MDLs) I 022603054 duc BLASLAND, BOUCK& LEE, INC an ARCADIS company