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amec— <br /> TABLE <br /> OF CONTENTS <br /> Page <br /> 1.0 INTRODUCTION ............................................................................................................ 1 <br /> 1.1 BACKGROUND AND PURPOSE................................................................................ 1 <br /> 1.2 OBJECTIVES AND APPROACH ................................................................................2 <br /> 2.0 GROUNDWATER SAMPLE COLLECTION AND ANALYSIS ........................................2 <br /> 3.0 RESULTS AND DISCUSSION .......................................................................................4 <br /> 3.1 MAJOR AND MINOR ION COMPOSITION OF GROUNDWATER.....................................4 <br /> 3.1.1 Major Ions................................................................................................4 <br /> 3.1.2 Minor Ions................................................................................................6 <br /> 3.2 OVERVIEW OF POTENTIAL INTRINSIC REMEDIATION PROCESSES ............................7 <br /> 3.2.1 Redox Conditions and Biodegradation....................................................7 <br /> 3.2.2 Aquifer Minerals and Abiotic Degradation...............................................8 <br /> 3.3 COMPOUND SPECIFIC ISOTOPE ANALYSIS (CSIA)..................................................9 <br /> 3.3.1 Overview of CSIA....................................................................................9 <br /> 3.3.2 Stable Carbon, Chlorine and Hydrogen Isotope Ratios of CDCs in <br /> Groundwater.......................................................................................... 12 <br /> 3.3.3 Direct Evidence of Net COC Destruction .............................................. 13 <br /> 3.3.4 Quantitative Assessment and Timeframe of COC Destruction ............. 15 <br /> 4.0 CONCLUSIONS............................................................................................................ 18 <br /> 5.0 REFERENCES .............................................................................................................18 <br /> TABLES <br /> Table B.4-1 Summary of Monitoring Wells Sampled for Intrinsic Remediation Parameters <br /> Table B.4-2 Results of 2008 Intrinsic Remediation Sampling <br /> Table B.4-3 Major and Minor Ion Composition of Groundwater Samples <br /> Table B.4-4 Redox Conditions and Potential Degradation Pathways <br /> Table B.4-5 Compound Specific Isotope Analytical Results <br /> Table B.4-6 Calculations of Timeframe for COC Degradation <br /> FIGURES <br /> Figure B.4-1 Intrinsic Remediation Assessment Area <br /> Figure B.4-2 Piper Diagram Depicting Major Ion Composition of Groundwater <br /> Figure B.4-3 Nitrate and Chloride vs. Boron Concentrations <br /> Figure B.4-4 Stable Carbon and Chlorine Isotope Composition of TCE in Groundwater <br /> Samples <br /> Figure B.4-5 Stable Carbon and Hydrogen Isotope Composition of TCE in Groundwater <br /> Samples <br /> Figure B.4-6 Stable Carbon Isotope Composition of TCE vs. cDCE in Groundwater Samples <br /> Figure B.4-7 Enrichment in 13C of chlorinated COCs with Distance from WWTP <br /> AMEC Geomatrix, Inc. <br /> \\oad-fs1\doc_safe\9000s\9837.006\4000 REGULATORYTS Assessment_Apx B_012711\Attachment B.4\Attach B-4.docx 134-i <br />