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2003 Site Assessment Report <br /> July 18, 2003 S E G O R - <br /> Page i <br /> • <br /> TABLE OF CONTENTS <br /> 1.0 INTRODUCTION........................................................................................................1 <br /> 1.1 Objectives.................................................................................................................................1 <br /> 2.0 SITE BACKGROUND ................................................................................................1 <br /> 2.1 Geology....................................................................................................................................2 <br /> 2.2 Hydrogeology...........................................................................................................................2 <br /> 2.2.1 Groundwater Flow Rates, Directions, Recharge, and Discharge...........................3 <br /> 2.2.2 Groundwater Use.........................................................................................................3 <br /> 2.2.3 Extraction Wells Affect on Groundwater Flow.........................................................3 <br /> 2.3 Surface Water..........................................................................................................................4 <br /> 2.4 Hydraulic Connection with Aquifers.........................................................................................4 <br /> 2.5 Local Land Use........................................................................................................................4 <br /> 2.6 Previous Investigations and Remedial Actions........................................................................4 <br /> 3.0 NATURE AND EXTENT OF CONTAMINATION........................................................8 <br /> 3.1 Soil Contamination...................................................................................................................8 <br /> 3.2 Groundwater Contamination....................................................................................................9 <br /> 4.0 CONTAMINANT FATE AND TRANSPORT........:.:..... ...... .:....:..:..........................9 <br /> 4.1 Contaminant Fate and Transport Properties. 9 <br /> 4.1.1 Mobility.......................................................................................................................10 <br /> 4.1.2 Toxicity.......................................................................................................................11 <br /> 4.2 Model Selection......................................................................................................................12 <br /> 4.3 Modeling Strategy..................................................................................................................12 <br /> 4.4 AT123D Simulations ..............................................................................................................13 <br /> 4.4.1 Simulation parameters..............................................................................................13 <br /> 4.4.2 Simulation Controls and Aquifer/Source Definition ..............................................13 <br /> 4.4.3 Soil and Waste Properties........................................................................................14 <br /> 4.4.4 X,Y, and Z Coordinates............................................................................................14 <br /> 4.4.5 Model Limitations......................................................................................................15 <br /> 4.5 Simulation Results .................................................................................................................15 <br /> 4.6 Conclusions............................................................................................................................16 <br /> 5.0 REMEDIAL OBJECTIVES .......................................................................................16 <br /> 6.0 REMEDIAL ALTERNATIVES...................................................................................16 <br /> 6.1 Groundwater Barrier...............................................................................................................16 <br /> 6.2 Hydraulic Control Line............................................................................................................16 <br /> 6.3 Combination Groundwater Barrier and Hydraulic Control Line..............................................17 <br /> 6.4 Groundwater Oxygenation System........................................................................................17 <br /> 7.0 EVALUATION OF REMEDIAL ALTERNATIVES.....................................................18 <br /> 7.1 Groundwater Barrier............................................................................................................... 18 <br /> 7.2 Hydraulic Control Line............................................................................................................19 <br /> 7.3 Combination Groundwater Barrier and Hydraulic Control Line..............................................20 <br /> 7.4 Groundwater Oxygenation System........................................................................................21 <br /> I:\Chevron\1001621\REPORTS\2003\2003FS\FS 2003 revD.doc <br />