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C Report: Groundwater-quality Monitoring—January 26,2004: 7500 West,Eleventh Street, Tracy, CA. Page i <br /> ,£ Table of Contents <br /> PROFESSIONAL CERTIFICATION AND LIMITATIONS..................................." <br /> as <br /> 1.0 INTRODUCTION <br /> ' 1.1 Site Location......................................................................................................................... 1 <br /> 1.2 Site Codes............................................................................................................................. 1 <br /> 1.3 Background............................... <br /> ..................:............... <br /> ................ <br /> ............. <br /> ....... <br /> .....................2 <br /> 1.4 Geology and Hydrogeology ..........................................................................I.—..................3 <br /> 1.5 Distribution of Hydrocarbons in the Subsurface..................................................................4 <br /> 2.0 JANUARY 26,2004 GROUNDWATER SAMPLING AND ANALYSIS.............................6 <br /> 2.1 Groundwater Elevations and Flow Direction.......................................................................6 <br /> 2.2 Purging of Monitoring Wells................................................................................................7 <br /> 2.2.1 Disposal of Purge Water...............................................................................................8 <br /> _ 2.3 Recovery of Groundwater Samples from Monitoring Wells................................................8 <br /> 2.4 Analyses of Groundwater Samples ......................................................................................8 <br /> 2.4.1 Groundwater Quality in the Near-Surface Unconfined Aquifer...................................9 <br /> Yf 2.4.1.1 Analytes of Concern in Groundwater Along Principal Plume Axis......................9 <br /> 2.4.1.2 Fuel Hydrocarbons and Oxygenates Around Fringes of Principal Plume........... 10 <br /> 2.4.1.3 Analytes of Concern in Secondary Groundwater Plume.....................................11 <br /> 2.4.2 Groundwater Quality in the Deeper Confined Aquifers............................................. I I <br /> 3.0 INTERIM MEASURES TO MANAGE FLOATING PRODUCT IN AREA OF <br /> MONITORING WELL MW-7.............................................................................................. 12 <br /> 3.1 Measurement of Thickness of LNAPL............................................................................... 12 <br /> 3.2 LNAPL Purging Technique................................................................................................ 12 <br /> 3.3 Floating Product Removed to Date ........ 13 <br /> 3.4 Evaluation of LNAPL Removed from Monitoring Well MW-7 Compared to Estimated <br /> Volume in Subsurface <br /> 4.0 FUTURE ROUNDS OF GROUNDWATER SAMPLING AND ANALYSIS ..................... 15 <br /> 5.0 FUTURE ROUNDS OF LNAPL PURGING FROM MW-7................................................. 16 <br /> 6.0 REFERENCES....................................................................................................................... 17 <br /> TABLES <br /> i <br /> Table 1: Depths to Groundwater <br /> Table 2: Results of Analyses of Samples of Groundwater <br /> 4L Table 3: Thickness of Floating Product in Monitoring Well MW-7 <br /> sic <br />