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Home My WebLink AboutSynTerra CAP Part 1 TOC_20160418Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant SynTerra TABLE OF CONTENTS SECTION PAGE ASHEVILLE STEAM ELECTRIC PLANT — CORRECTIVE ACTION PLAN EXECUTIVE SUMMARY.................................................................................................... ES-1 ES-1. Introduction.......................................................................................................... ES-2 ES-2. Site Conceptual Model........................................................................................ ES-3 ES-3. Extent of 2L and 2B Exceedances....................................................................... ES-5 ES-4. Receptor Survey................................................................................................... ES-5 ES-4.1 Public Water Supply Wells....................................................................... ES-6 ES-4.2 Private Water Supply Wells...................................................................... ES-6 ES-4.3 Human and Ecological Receptors............................................................ ES-6 ES-5. Geochemical Modeling Results.......................................................................... ES-7 ES-6. Groundwater Modeling Results........................................................................ ES-8 ES-7. Corrective Actions to be Evaluated Based on Provisional Background Concentrations...................................................................................................... ES-9 1.0 INTRODUCTION.........................................................................................................1-1 1.1 Site History and Overview....................................................................................1-1 1.2 Purpose of Corrective Action Plan.......................................................................1-2 1.3 Regulatory Background.........................................................................................1-3 1.3.1 15A NCAC 2L .0106 Requirements.............................................................1-3 1.3.2 Coal Ash Management Act Requirements ................................................1-4 1.3.3 Regulatory Standards for Site Media.........................................................1-5 1.3.4 NCDEQ Requirements.................................................................................1-6 1.3.5 NORR Requirements....................................................................................1-6 1.4 Summary of CSA Findings....................................................................................1-6 1.5 Site Description.......................................................................................................1-7 1.6 Site Geology.............................................................................................................1-8 1.7 Site Hydrogeology..................................................................................................1-8 1.8 Site Hydrology........................................................................................................1-9 1.9 Receptor Survey......................................................................................................1-9 1.9.1 Availability of Public Water Supply...........................................................1-9 1.9.2 Public Water Supply Wells..........................................................................1-9 1.9.3 Private Water Supply Wells.......................................................................1-10 Page i P:\Duke Energy Progress. 1026 \ 102. Asheville Ash Basin GW Assessment Plan\16.Corrective Action Plan\Text\Final Asheville CAP.docx Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant SynTerra TABLE OF CONTENTS SECTION PAGE 2.0 3.0 2.1 2.2 2.3 2.4 1.9.4 Potential Human Receptors.......................................................................1-10 1.9.5 Potential Ecological Receptors...................................................................1-11 BACKGROUND CONCENTRATIONS AND EXTENT OF EXCEEDANCES 2-1 Provisional Background Concentrations.............................................................2-1 2.1.1 Provisional Background Soil Concentrations ............................................ 2-2 2.1.2 Provisional Background Groundwater Concentrations .......................... 2-3 2.1.3 Duke Energy Private Background Well Sampling Summary.................2-9 2.1.4 Provisional Background Surface Water Concentrations ......................... 2-9 2.1.5 Provisional Background Sediment Concentrations ................................ 2-12 Exceedances........................................................................................................... 2-12 Areas to be Considered for Corrective Action or Further Evaluation .......... 2-13 2.3.1 Soil.................................................................................................................2-13 2.3.2 Groundwater................................................................................................2-15 2.3.2.1 Surficial Groundwater........................................................................ 2-15 2.3.2.2 Transition Zone Groundwater.......................................................... 2-16 2.3.2.3 Bedrock Groundwater........................................................................ 2-16 2.3.2.4 Receptor Wells..................................................................................... 2-17 2.3.3 Surface Water............................................................................................... 2-17 2.3.4 Sediment....................................................................................................... 2-18 Initial and Interim Response Actions.................................................................2-18 SITE CONCEPTUAL MODEL................................................................................... 3-1 3.1 Site Hydrogeological Conditions..........................................................................3-1 3.1.1 Hydrostratigraphic Units............................................................................. 3-1 3.1.2 Potentiometric Surfaces................................................................................ 3-2 3.1.3 Horizontal Hydraulic Gradients................................................................. 3-2 3.1.4 Vertical Hydraulic Gradients....................................................................... 3-2 3.2 Geochemical Site Conceptual Model................................................................... 3-3 3.3 Mineralogical Characteristics of Soils.................................................................. 3-3 3.3.1 Constituent Transport and Distribution in Groundwater ....................... 3-4 3.3.1.1 Major Anions and Cations................................................................... 3-4 Page ii P:\Duke Energy Progress. 1026 \ 102. Asheville Ash Basin GW Assessment Plan\16.Corrective Action Plan\Text\Final Asheville CAP.docx Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant SynTerra TABLE OF CONTENTS SECTION PAGE 3.3.1.2 Oxidation and pH Conditions............................................................. 3-5 3.3.1.3 Solute Speciation................................................................................... 3-5 3.3.1.4 Facilitated (Colloidal) Transport......................................................... 3-6 3.3.2 Correlation of Hydrogeologic and Geochemical Conditions to Constituent Distribution............................................................................... 3-7 4.0 MODELING...................................................................................................................4-1 4.1 Determination of Distribution Coefficient.......................................................... 4-1 4.2 Geochemical Modeling.......................................................................................... 4-3 4.3 Numerical Fate and Transport Model................................................................. 4-5 4.3.1 Flow and Transport Models......................................................................... 4-6 4.3.2 Model Scenarios.............................................................................................4-S 4.3.2.1 Existing Conditions.............................................................................. 4-9 4.3.2.2 Capping Ash Basins.............................................................................. 4-9 4.3.2.3 Removal of Ash................................................................................... 4-10 4.4 Groundwater and Surface Water Interactions..................................................4-12 4.4.1 Flow Considerations................................................................................... 4-12 4.4.2 Concentration of a Constituent................................................................. 4-14 4.4.3 Results........................................................................................................... 4-15 4.4.4 Sensitivity Analysis..................................................................................... 4-15 5.0 CORRECTIVE ACTION PLAN PART 2..................................................................5-1 6.0 REFERENCES................................................................................................................ 6-1 Page iii P:\Duke Energy Progress. 1026 \ 102. Asheville Ash Basin GW Assessment Plan\16.Corrective Action Plan\Text\Final Asheville CAP.docx Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant LIST OF FIGURES Executive Summary Figure ES-1 Plan View Conceptual Site Model Figure ES-2 Cross -Section View Conceptual Site Model Figure ES-3 Cross Section View Post Excavation Section 1 Introduction Figure 1-1 Site Location Map Figure 1-2 Site Layout Map Figure 1-3 Drinking Water Well and Receptor Survey SynTerra Section 2 Extent of 21, and 2B Exceedances Figure 2-1 Areas of Protection of Groundwater Standard and Provisional Background Exceedance in Soils Figure 2-2 Areas of 2L and Provisional Background Exceedances in Surficial Groundwater Figure 2-3 Areas of 2L and Provisional Background Exceedances in Transition Zone Groundwater Figure 2-4 Areas of 2L and Provisional Background Exceedances in Bedrock Groundwater Section 3 Site Conceptual Model Figure 3-1 Water Level Map- Surficial- June 29,2015 Figure 3-2 Water Level Map- Bedrock- June 29,2015 Figure 3-3 Potential Gradient Between Hydrostratigraphic Units Figure 3-4 Isoconcentration Maps - Eh in Ash Pore Water Figure 3-5 Isoconcentration Maps - Eh in Surficial Groundwater Figure 3-6 Isoconcentration Maps - Eh in Transition Zone Groundwater Figure 3-7 Isoconcentration Maps - Eh in Bedrock Groundwater Figure 3-8 Isoconcentration Maps - Eh in Seeps and Surface Water Figure 3-9 Isoconcentration Maps - pH in Ash Pore Water Figure 3-10 Isoconcentration Maps - pH in Surficial Groundwater Figure 3-11 Isoconcentration Maps - pH in Transition Zone Groundwater Figure 3-12 Isoconcentration Maps - pH in Bedrock Groundwater Figure 3-13 Isoconcentration Maps - pH in Seeps and Surface Water Figure 3-14 Isoconcentration Maps - DO in Ash Pore Water Figure 3-15 Isoconcentration Maps - DO in Surficial Groundwater Page iv P: \Duke Energy Progress.1026 \ 102. Asheville Ash Basin GW Assessment Plan\ 16.Corrective Action Plan\Text\ Final Asheville CAP.docx Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant SynTerra Figure 3-16 Isoconcentration Maps - DO in Transition Zone Groundwater Figure 3-17 Isoconcentration Maps - DO in Bedrock Groundwater Figure 3-18 Isoconcentration Maps - DO in Seeps and Surface Water Figure 3-19 Isoconcentration Maps - Specific Conductance in Ash Pore Water Figure 3-20 Isoconcentration Maps - Specific Conductance in Surficial Groundwater Figure 3-21 Isoconcentration Maps - Specific Conductance in Transition Zone Groundwater Figure 3-22 Isoconcentration Maps - Specific Conductance in Bedrock Groundwater Figure 3-23 Isoconcentration Maps - Specific Conductance in Seeps and Surface Water Figure 3-24 Isoconcentration Maps - Strontium in Ash Pore Water Figure 3-25 Isoconcentration Maps - Strontium in Surficial Groundwater Figure 3-26 Isoconcentration Maps - Strontium in Transition Zone Groundwater Figure 3-27 Isoconcentration Maps - Strontium in Bedrock Groundwater Figure 3-28 Isoconcentration Maps - Strontium in Seeps and Surface Water Figure 3-29 Boron, Sulfate, TDS, and Strontium in Ash Pore Water Figure 3-30 Boron, Sulfate, TDS, and Strontium in Surficial Groundwater Figure 3-31 Boron, Sulfate, TDS, and Strontium in Transition Zone Groundwater Figure 3-32 Boron, Sulfate, TDS, and Strontium in Bedrock Groundwater Figure 3-33 Boron, Sulfate, TDS, and Strontium in Surface Water and Seeps Figure 3-34 Time vs. Boron Concentration Graphs Section 4 Modeling Figure 4-1 Computed vs Observed Values Figure 4-2 Map of preliminary basin closure for the CAP2 scenario Figure 4-3 Simulated hydraulic heads Figure 4-4 Conceptual figure of groundwater discharge to the French Broad River Page v P: \Duke Energy Progress.1026 \ 102. Asheville Ash Basin GW Assessment Plan\ 16.Corrective Action Plan\Text\ Final Asheville CAP.docx Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant LIST OF TABLES SynTerra Section 2 Extent of 2L and 2B Exceedances Table 2-1 Soil Provisional Background Concentration Summary Table 2-2 Background Well Analytical Results Table 2-3 SSI Analyte Summary Table 2-4 Surficial Groundwater Provisional Background Concentration Summary Table 2-5 Transition Zone Provisional Background Concentration Summary Table 2-6 Bedrock Provisional Background Concentration Summary Table 2-7 Duke Energy Private Background Well Summary Table 2-8 Surface Water Provisional Background Concentration Summary Table 2-9 Sediment Provisional Background Concentration Summary Table 2-10 Hexavalent Chromium Analytical Results Table 2-11 Soil Exceedances Table 2-12 Alluvial Groundwater Exceedances Table 2-13 Saprolite Groundwater Exceedances Table 2-14 Transition Zone Groundwater Exceedances Table 2-15 Bedrock Groundwater Exceedances Table 2-16 Surface Water Exceedances Table 2-17 Sediment Exceedances Section 3 Site Conceptual Model Table 3-1 Local Groundwater Gradients and Flow Velocities Table 3-2 Potential Vertical Gradients Between Hydrostratigraphic Units Table 3-3 0.1 Micron Analytical Data Summary Section 4 Modeling Table 4-1 Summary of Kd Values from Batch and Column Studies Page vi P: \Duke Energy Progress.1026 \ 102. Asheville Ash Basin GW Assessment Plan\ 16.Corrective Action Plan\Text\ Final Asheville CAP.docx Corrective Action Plan Part 1 November 2015 Asheville Steam Electric Plant LIST OF APPENDICES Appendix A Site Specific Soil Remediation Goal Development (Graphs) Appendix B Soil Sorption Evaluation Appendix C Geochemical Modeling Report Appendix D Groundwater Modeling Report Appendix E Analytical Data Laboratory Reports SynTerra Page vii P: \Duke Energy Progress.1026 \ 102. Asheville Ash Basin GW Assessment Plan\ 16.Corrective Action Plan\Text\ Final Asheville CAP.docx