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ARCADIS Mr. Eric Rapport <br /> April 21, 2011 <br /> RWQCB approved the Tech Memo recommendations in a letter dated December 9, <br /> 2009. <br /> This data is being used to evaluate the interconnection between groundwater and <br /> surface water. During the January 2011 event, groundwater samples collected from <br /> wells MW-05A, MW-07A, MW-08, MW-09, MW-10, MW-11, MW-12 and MW-13 were <br /> analyzed for the following: <br /> cc alkalinity by EPA Method SM2320B <br /> 00 total dissolved solids (TDS) by EPA Method 40 CFR 136/160.1 <br /> 00 major cations: sodium, potassium, calcium, and magnesium by EPA Method 200.7 <br /> 30 major anions: bicarbonate, carbonate, sulfate, chloride, nitrate, nitrite, and <br /> phosphate by EPA Method 300.0 <br /> Groundwater Monitoring and Sampling Results <br /> Groundwater Elevations <br /> Groundwater elevations were calculated by subtracting the depth to groundwater from <br /> the surveyed elevation at the measuring point. Calculated groundwater elevations <br /> were then used to estimate the groundwater flow direction and gradient. Groundwater <br /> flow direction and gradient are similar to previous sampling events. January 2011 <br /> groundwater elevations in alluvium and bedrock wells are illustrated in Figures 3 and <br /> 4. A summary of groundwater elevations is provided in Table 2. <br /> Groundwater Analytical Results <br /> Groundwater analytical results are generally similar to previous sampling events; <br /> ethanol was not detected during the first quarter 2011 event. Historical and first <br /> quarter 2011 analytical data are summarized in Table 3. Additional groundwater <br /> geochemistry results for the first quarter 2011 are summarized in Table 4. Benzene <br /> and ethanol analytical results are presented on Figures 5 and 6. Laboratory analytical <br /> reports with chain-of-custody documentation are presented in Attachment 2. <br /> Purge Water Waste Management <br /> Purge water generated during groundwater sampling activities is temporarily stored <br /> onsite in a 5,000-gallon polypropylene tank. Transportation and disposal of the purge <br /> water will be conducted by UPRR's subcontractor, United Pumping Service, Inc. <br /> 1\Arcadis-us\officedatalFolsom-CA\Aproject\UPRR\RC000738-UP RR-StorrieTeliverables\QuarterlyReports120111Q1-2011VIinaltedlQ-2011StorrieStatus Rpt(4-21- Page' <br /> 11).doc 4/9 <br />