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Exhibit 9 - FPL Turkey Point Remedial Action Annual Status Report Year 5
	ML23331A989
Person / Time
Site:	Turkey Point
Issue date:	11/15/2023
From:	; Miami Waterkeeper
To:	; NRC/SECY/RAS
	SECY RAS
References
	50-250-SLR-2, 50-251-SLR-2
	Download: ML23331A989 (0)
	v • d • e

EXHIBIT 9 TURKEY POINT CLEAN ENERGY CENTER Remedial Action Annual Status Report Year 5 November 15, 2023

FPL Turkey Point RAASR Year 5 November 2023 Table of Contents TABLE OF CONTENTS Section Page Executive Summary ................................................................. ES-1 1 Introduction ....................................................................... 1-1 1.1 Background .......................................................................................................... 1-1 1.1.1 FDEP Consent Order - MDC Concent Agreement ................................. 1-1 1.1.2 Remediation Formulation, Alternative Evaluation, and Implementation ........................................................................................ 1-2 1.1.3 Monitoring/Assessment of Remediaiton Progress ................................... 1-2 1.2 Scope of the Remedial Action Annual Status Report .......................................... 1-4 1.3 Status of Consent Agreement/Consent Order Implementation ............................ 1-6 2 Recovery Well System Year 5 Operation Summary ........... 2-1 2.1 Hypersaline Extraction/Disposal Operations ....................................................... 2-1 2.2 Recovery Well System Monitoring Results and Hypersaline Groundwater/Salt Mass Removed ..................................................................................................... 2-4 2.3 Recovery Well System Drawdown Assessment .................................................. 2-8 2.4 Interceptor Ditch Operations.............................................................................. 2-11 3 Groundwater Monitoring Data ........................................... 3-1 3.1 Groundwater Monitoring ..................................................................................... 3-1 3.2 Water Quality Conditions and Trends ................................................................. 3-9 3.2.1 Source Area Wells ................................................................................... 3-9 3.2.2 Trends for Monitoring Wells West and North of the CCS .................... 3-10 3.3 Chloride Concentration Contour Maps .............................................................. 3-21 3.4 Groundwater Level Trends ................................................................................ 3-31 4 Continuous Surface Electromagnetic Survey Summary .... 4-1 4.1 Introduction .......................................................................................................... 4-1 4.2 Background .......................................................................................................... 4-2 4.3 Approach and Methods ........................................................................................ 4-4 4.3.1 Data Acquisition and Field Processing .................................................... 4-6 4.3.2 Quality Control of the AEM Data Inversion............................................ 4-8 4.3.3 Conversion of AEM Resistivity to Estimated Chloride Concentrations of Ground Water ........................................................... 4-12 4.3.4 Year 2023 Chloride Conversion ............................................................ 4-14 4.4 Bias-Adjusted Chloride Results ......................................................................... 4-18 4.4.1 AEM Layers and High Flow Zones ....................................................... 4-18 4.4.2 Volumetric Determination Methodologies and Spatial Comparison ..... 4-24 4.4.3 Statistical Significance of Plume Volume Changes 2018 to 2023 ........ 4-26 i

FPL Turkey Point RAASR Year 5 November 2023 Table of Contents 4.5 Discussion of Findings....................................................................................... 4-31 4.5.1 Natural Occurrence of Hypersaline Water ............................................. 4-31 4.5.2 Comparison of the 2018 and 2023 AEM Survey Results ...................... 4-32 4.5.3 Summary of 2023 AEM Survey Results ................................................ 4-45 4.5.4 Factors for Additional Evaluation .......................................................... 4-46 5 Groundwater Model ........................................................... 5-1 5.1 Model Overview and Evolution ........................................................................... 5-1 5.1.1 Objectives ................................................................................................ 5-1 5.1.2 Model Versions ........................................................................................ 5-2 5.1.3 Sensitivity Analysis with the Version 7 Model ....................................... 5-3 5.1.4 Description of Version 8 Model .............................................................. 5-4 5.2 Model Modifications/Calibration......................................................................... 5-6 5.2.1 Model Calibration Process ....................................................................... 5-6 5.2.2 Model Calibration Results ....................................................................... 5-7 5.3 Remediation Year 10 Forecast ............................................................................. 5-8 5.3.1 Description of Remediation Simulations ................................................. 5-8 5.3.2 Remediation Forecast............................................................................... 5-8 5.3.3 Model Recommendations ........................................................................ 5-9 6 Cooling Canal System Management .................................. 6-1 6.1 Cooling Canal System Salinity Management ...................................................... 6-1 6.2 Cooling Canal System Nutrient Management Plan ............................................. 6-3 6.3 Cooling Canal System Thermal Efficiency Plan ................................................. 6-5 6.4 Cooling Canal System Biotic Responses ............................................................. 6-5 7 Summary and Recommendations ....................................... 7-1 7.1 Overall Summary ................................................................................................. 7-1 7.2 Recommendations ................................................................................................ 7-4 8 References .......................................................................... 8-1 ii

FPL Turkey Point RAASR Year 5 Novem ber 2023 Table of Contents Appendices A Status of Consent Agreement and Consent Order Activities B Groundwater Remediation Extraction Well Results C RWS Analytical Data D Data Usability Summaries for RWS Analytical Results E Monitoring Well Trends F 2023 Year 5 CSEM Survey Report G Turkey Point Year 5 Chloride Modeling and Estimation H Permutation Testing and Bootstrap Estimation of the Hypersaline Plume at Turkey Point, Year 5 I Turkey Point Groundwater Remediation Project Year 5 Recovery Well System Evaluation Report J Documentation of the Groundwater Flow and Salt Transport Model of the Biscayne Aquifer (Version 8) iii

FPL Turkey Point RAASR Year 5 November 2023 List of Tables LIST OF TABLES Table Page 2.2 1. RWS Chloride Monitoring Results (mg/L). ................................................................ 2-5 2.2.2 Monthly RWS-1 through RWS-10 Volume Withdrawn (MG) .................................. 2-7 3.1-1. Monitoring Well Baseline and Year 5 Quarterly (Sept 2022 To June 2023) and September 2023 Chloride Concentration Data. .......................................................... 3-4 3.1-2. Monitoring Well Baseline and Year 5 Quarterly (Sept 2022 To June 2023) and September 2023 Field Salinity Sample Results. ......................................................... 3-5 3.1-3. Monitoring Well Baseline and Year 5 Quarterly (Sept 2022 To June 2023)

Tritium Concentration Data. ....................................................................................... 3-7 3.2-1. Mann-Kendall Trend Analyses for Wells that Were/Are Hypersaline. .................... 3-12 3.3-1. Chloride Concentrations for the 2018 TPGW and CSEM Monitoring Sites. ........... 3-23 3.3-1 Chloride Concentrations for the 2023 TPGW and CSEM Monitoring Sites ............ 3-24 4.3-1. Thickness and Depth to Bottom for Each Layer in the AEM Model.......................... 4-8 4.3-2. June 2023 Water Quality Data from TPGW Wells................................................... 4-13 4.3-3 Year Specific Deming Regression Coefficients ........................................................ 4-17 4.4-1. Deming Regression Chloride Concentrations for 2018 - Measured versus Deming Estimated ..................................................................................................... 4-18 4.4-2. Deming Regression Chloride Concentrations for 2019 - Measured versus Deming Estimated ..................................................................................................... 4-19 4.4-3. Deming Regression Chloride Concentrations for 2020 - Measured versus Deming Estimated ..................................................................................................... 4-20 4.4-4. Deming Regression Chloride Concentrations for 2021 - Measured versus Deming Estimated ..................................................................................................... 4-21 4.4-5. Deming Regression Chloride Concentrations for 2022 - Measured versus Deming Estimated ..................................................................................................... 4-22 iv

FPL Turkey Point RAASR Year 5 November 2023 List of Tables 4.4-6. Deming Regression Chloride Concentrations for 2023 - Measured versus Deming Estimated ..................................................................................................... 4-23 4.4-7. Bias Adjusted Chloride Concentration Volumes for 2018 and 2023 (in cubic meters) ...................................................................................................................... 4-25 4.5-1. Revised Estimates of Hypersaline Plume Volume Changes by Layer and Year ...... 4-45 5.1-1. Summary of Groundwater Model Versions. ............................................................. 5-11 5.1-2. Description of Sensitivity Evaluations and Simulations Performed with the V7 Model ........................................................................................................................ 5-13 5.2-1. Calibration Statistic Summary for the Version 8 Model. ............................................... 5-13 A.1-1 Permitting Activities Status ............................................................................................. A-1 A.1-2 Overall Status of Compliance Activities ........................................................................ A-5 A.1-3 Overall Status of Additional Activities............................................................................ A-8 B.1-1 Weekly Summary of RWS Volume Pumped, Salt Mass Removed, Salinity, and TDS ..................................................................................................................B.1-1 B.2-1 Weekly Summary of UICPW-1 and -2 Volume Pumped, Salt Mass Removed, Salinity, and TDS ....................................................................................................B.2-1 B.4-1 Automated RWS Qualifier Table (July 2022 - June 2023) .....................................B.4-1 C.1-1 Summary of RWS Analytical Results from the July 2022 Sampling Event ............C.1-1 C.1-2 Summary of RWS Analytical Results from the August 2022 Sampling Event .......C.1-1 C.1-3 Summary of RWS Analytical Results from the September 2022 Sampling Event ........................................................................................................................C.1-2 C.1-4 Summary of RWS Analytical Results from the October 2022 Sampling Event......C.1-2 C.1-5 Summary of RWS Analytical Results from the November 2022 Sampling Event ........................................................................................................................C.1-3 C.1-6 Summary of RWS Analytical Results from the December 2022 Sampling Event ........................................................................................................................C.1-3 C.1-7 Summary of RWS Analytical Results from the January 2023 Sampling Event ......C.1-4 C.1-8 Summary of RWS Analytical Results from the February 2023 Sampling Event ....C.1-4 C.1-9 Summary of RWS Analytical Results from the March 2023 Sampling Event ........C.1-5 v

FPL Turkey Point RAASR Year 5 November 2023 List of Tables C.1-10 Summary of RWS Analytical Results from the April 2023 Sampling Event ..........C.1-5 C.1-11 Summary of RWS Analytical Results from the May 2023 Sampling Event ...........C.1-6 C.1-12 Summary of RWS Analytical Results from the June 2023 Sampling Event ...........C.1-6 C.3-1 RWS Data Removed from Analysis ........................................................................C.3-1 vi

FPL Turkey Point RAASR Year 5 November 2023 List of Figures LIST OF FIGURES Figure Page 2.1-1. Operation of RWS in Year 5 (Pumping With More Than 4 Hours Of Daily Flow) ........................................................................................................................... 2-3 2.2-1. RWS Chloride Results (mg/L). ................................................................................... 2-6 2.3-1. Groundwater Elevation and Salinity at TPGW-1 ..................................................... 2-10 2.3-2. Groundwater Elevation at TPGW-1S and TPGW-5S ............................................... 2-11 3.1-1 RWS and Monitoring Wells West and North of the CCS Used in the Assessment of the RWS .............................................................................................. 3-3 3.2-1. Declining Saltwater Values in CCS Source Well Cluster TPGW-13. ...................... 3-10 3.2-2. Trends in Chloride, Salinity and Tritium for Select Hypersaline Monitoring Wells ......................................................................................................................... 3-13 3.2-3. Regression Analyses Trends for Select Hypersaline Wells Between CCS and L-31E ........................................................................................................................ 3-14 3.2-4. Regression Analyses Trends for Select Wells in Compliance Zone ......................... 3-15 3.2-5. Summarized Changes in the Shallow, Intermediate, and Deep Well Chloride Concentrations .......................................................................................................... 3-17 3.2-6. Summarized Changes in the Shallow, Intermediate, and Deep Well Tritium Concentrations .......................................................................................................... 3-18 3.2-7. Progress of Chloride Reduction in Currently Hypersaline Wells ............................. 3-20 3.2-8. Declining Trend in Chloride Concentration in TPGW-5M and TPGW-G21 (58) since March 2021 .............................................................................................. 3-21 3.3-1. Groundwater Chloride Contour Map based on 2023 Shallow Monitoring Well Data and CSEM Horizon Chloride Values. .............................................................. 3-25 3.3-2. Groundwater Chloride Contour Map based on 2023 Middle Monitoring Well Data and CSEM Horizon Chloride Values. .............................................................. 3-26 3.3-3. Groundwater Chloride Contour Map based on 2023 Deep Monitoring Well Data and CSEM Horizon Chloride Values. .............................................................. 3-27 vii

FPL Turkey Point RAASR Year 5 November 2023 List of Figures 3.3-4. Comparison of the 2018 Baseline and 2023 Year 5 Inland Extent of Hypersaline Groundwater (19,000 mg/L Chloride Isochlor) Based on Shallow Horizon Monitoring Well Data. ................................................................................ 3-28 3.3-5. Comparison of the 2018 Baseline and 2023 Year 5 Inland Extent of Hypersaline Groundwater (19,000 Mg/L Chloride Isochlor) Based on Middle Horizon Monitoring Well Data. .............................................................................................. 3-29 3.3-6. Comparison of the 2018 Baseline and 2023 Year 5 Inland Extent of Hypersaline Groundwater (19,000 mg/L Chloride Isochlor) Based on Deep Horizon Monitoring Well Data. .............................................................................................. 3-30 3.4-1. Dry Season Water Level Contour Map (April 1, 2023). ........................................... 3-32 3.4-2. Wet Season Water Level Contour Map (September 24, 2022)................................. 3-33 4.3-1. 2023 AEM Survey Area, Flight Lines, Monitoring Well Locations and Designation of Compliance Area Boundary (Orange Line) ....................................... 4-5 4.3-2. Monitor Well Screened Zone versus AEM Layer....................................................... 4-9 4.3-3. Locations of the Decoupled and Removed Data (Red Lines) Along the AEM Flight Lines and the Data Used in the Inversion ....................................................... 4-10 4.3-4. Log-Log Linear Regression Between Fluid Resistivity and Chloride ...................... 4-14 4.3-5. Variation in Cementation Factors (Mean +/- SD) By Zone Depth and Year ........... 4-16 4.3-6. Observed Versus Bias Adjusted AEM Resistivity .................................................... 4-16 4.4-1. Trends in Bias Adjusted Hypersaline Chloride......................................................... 4-26 4.4-2. Bootstrapped Trend in Percent Hypersaline Plume Volume by Layer Per Year ...... 4-30 4.5-1. Layer 6, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ........... 4-36 4.5-2. Layer 7, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ........... 4-37 4.5-3. Layer 8, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ........... 4-38 4.5-4. Layer 9, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ........... 4-39 4.5-5. Layer 10, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ......... 4-40 4.5-6. Layer 11, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ......... 4-41 4.5-7. Layer 12, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ......... 4-42 4.5-8. Layer 13, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ......... 4-43 4.5-9. Layer 14, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 ......... 4-44 viii

FPL Turkey Point RAASR Year 5 November 2023 List of Figures 5.1-1. Model Study Area Overlain by the Active Model Grid; Red Dashed Line Represents the Location of the Model Cross Section Shown in 5.1-2. ..................... 5-14 5.1-2. Model Cross Section Showing Model Layering and Hydrogeologic Formations (Location of Cross Section Shown in 5.1-1). ............................................................ 5-15 5.2-1. Comparison of Model and Observed Changes in Relative Salinity with Time by Well between April 2018 and May 2023. ............................................................ 5-16 5.2-2. Comparison of Model and Observed Total Mass Extracted by the RWS between May 2018 and May 2023. ........................................................................... 5-18 5.2-3. Comparison of Model and Observed Mass Extracted by Well between May 2018 and May 2023................................................................................................... 5-19 5.3-1a. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 4. ..................................................................................................................... 5-20 5.3-1b. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 9. ..................................................................................................................... 5-21 5.3-1c. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 13. ................................................................................................................... 5-22 5.3-1d. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 16. ................................................................................................................... 5-23 5.3-2. Predicted Ten-Year Capture Zones for Model Layers (From Top Left to Bottom Left) 2, 4, 6 and (From Top Right to Bottom Right) 10, 13, 16 .................. 5-24 6.1-1. TPGW-13S Quarterly Salinity Trends ........................................................................ 6-2 6.1-2. Declining Trend in CCS Salinity Over Time .............................................................. 6-3 6.2-1. CCS Average TN and TP Concentrations................................................................... 6-4 6.4-1. Time Series of (A) CCS Algae Concentrations, (B) Turbidity, (C) Secchi Disk and (D) Chlorophyll-a Concentrations........................................................................ 6-7 6.4-2 Average Quarterly CCS Dissolved Oxygen: June 2015 through September 2023 ............................................................................................................................. 6-7 B.3-1 RWS-1 Salinity and Flow .......................................................................................B.3-1 B.3-2 RWS-2 Salinity and Flow .......................................................................................B.3-1 B.3-3 RWS-3 Salinity and Flow ........................................................................................B.3-2 ix

FPL Turkey Point RAASR Year 5 November 2023 List of Figures B.3-4 RWS-4 Salinity and Flow ........................................................................................B.3-2 B.3-5 RWS-5 Salinity and Flow ........................................................................................B.3-3 B.3-6 RWS-6 Salinity and Flow ........................................................................................B.3-3 B.3-7 RWS-7 Salinity and Flow ........................................................................................B.3-4 B.3-8 RWS-8 Salinity and Flow ........................................................................................B.3-4 B.3-9 RWS-9 Salinity and Flow ........................................................................................B.3-5 B.3-10 RWS-10 Salinity and Flow ......................................................................................B.3-5 C.4-1 Mann-Kendall Chloride Results for RWS-1 (March 2018 - June 2023) ................C.4-1 C.4-2 Mann-Kendall Chloride Results for RWS-2 (March 2018 - June 2023).................C.4-2 C.4-3 Mann-Kendall Chloride Results for RWS-3 (March 2018 - June 2023).................C.4-3 C.4-4 Mann-Kendall Chloride Results for RWS-4 (March 2018 - June 2023).................C.4-4 C.4-5 Mann-Kendall Chloride Results for RWS-5 (March 2018 - June 2023).................C.4-5 C.4-6 Mann-Kendall Chloride Results for RWS-6 (March 2018 - June 2023).................C.4-6 C.4-7 Mann-Kendall Chloride Results for RWS-7 (March 2018 - June 2023).................C.4-7 C.4-8 Mann-Kendall Chloride Results for RWS-8 (March 2018 - June 2023).................C.4-8 C.4-9 Mann-Kendall Chloride Results for RWS-9 (March 2018 - June 2023).................C.4-9 C.4-10 Mann-Kendall Chloride Results for RWS-10 (March 2018 - June 2023).............C.4-10 E.1-1 TPGW-1 Analytical Chloride and Salinity (March 2018 - September 2023) ......... E.1-1 E.1-2 TPGW-2 Analytical Chloride and Salinity (March 2018 - September 2023) ......... E.1-2 E.1-3 TPGW-12 Analytical Chloride and Salinity (March 2018 - September 2023) ....... E.1-3 E.1-4 TPGW-15 Analytical Chloride and Salinity (March 2018 - September 2023) ....... E.1-4 E.1-5 TPGW-17 Analytical Chloride and Salinity (March 2018 - September 2023) ....... E.1-5 E.1-6 TPGW-18 Analytical Chloride and Salinity (March 2018 - September 2023) ....... E.1-6 E.1-7 TPGW-19 Analytical Chloride and Salinity (March 2018 September 2023) .......... E.1-7 E.1-8 TPGW-22 Analytical Chloride and Salinity (March 2021 - September 2023) ....... E.1-8 E.1-9 TPGW-L3-58 Analytical Chloride and Salinity (March 2018 - September 2023) ........................................................................................................................ E.1-9 E.1-10 TPGW-L5-58 Analytical Chloride and Salinity (March 2018 - September 2023) ........................................................................................................................ E.1-9 x

FPL Turkey Point RAASR Year 5 November 2023 List of Figures E.2-1 TPGW-1 Analytical Tritium (March 2018 - June 2023) ......................................... E.2-1 E.2-2 TPGW-2 Analytical Tritium (March 2018 - June 2023) ......................................... E.2-2 E.2-3 TPGW-12 Analytical Tritium (March 2018 - June 2023) ....................................... E.2-3 E.2-4 TPGW-15 Analytical Tritium (March 2018 - June 2023) ....................................... E.2-4 E.2-5 TPGW-17 Analytical Tritium (March 2018 - June 2023) ....................................... E.2-5 E.2-6 TPGW-18 Analytical Tritium (March 2018 - June 2023) ....................................... E.2-6 E.2-7 TPGW-19 Analytical Tritium (March 2018 - June 2023) ....................................... E.2-7 E.2-8 TPGW-22 Analytical Tritium (March 2021 - June 2023) ....................................... E.2-8 E.2.9 TPGW-L3-58 Analytical Tritium (March 2018 - June 2023) ................................. E.2-9 E.2-10 TPGW-L5-58 Analytical Tritium (March 2018 - June 2023) ................................. E.2-9 E.3-1.1 Mann-Kendall Chloride Results for TPGW-1S ....................................................... E.3-1 E.3-1.2 Mann-Kendall Chloride Results for TPGW-1M ...................................................... E.3-2 E.3-1.3 Mann-Kendall Chloride Results for TPGW-1D ...................................................... E.3-3 E.3-1.4 Mann-Kendall Chloride Results for TPGW-2S ....................................................... E.3-4 E.3-1.5 Mann-Kendall Chloride Results for TPGW-2M ...................................................... E.3-5 E.3-1.6 Mann-Kendall Chloride Results for TPGW-2D ...................................................... E.3-6 E.3-1.7 Mann-Kendall Chloride Results for TPGW-12S ..................................................... E.3-7 E.3-1.8 Mann-Kendall Chloride Results for TPGW-12M .................................................... E.3-8 E.3-1.9 Mann-Kendall Chloride Results for TPGW-12D .................................................... E.3-9 E.3-1.10 Mann-Kendall Chloride Results for TPGW-15S ................................................... E.3-10 E.3-1.11 Mann-Kendall Chloride Results for TPGW-15M .................................................. E.3-11 E.3-1.12 Mann-Kendall Chloride Results for TPGW-15D .................................................. E.3-12 E.3-1.13 Mann-Kendall Chloride Results for TPGW-17S ................................................... E.3-13 E.3-1.14 Mann-Kendall Chloride Results for TPGW-17M .................................................. E.3-14 E.3-1.15 Mann-Kendall Chloride Results for TPGW-17D .................................................. E.3-15 E.3-1.16 Mann-Kendall Chloride Results for TPGW-18S ................................................... E.3-16 E.3-1.17 Mann-Kendall Chloride Results for TPGW-18M .................................................. E.3-17 E.3-1.18 Mann-Kendall Chloride Results for TPGW-18D .................................................. E.3-18 E.3-1.19 Mann-Kendall Chloride Results for TPGW-19S ................................................... E.3-19 E.3-1.20 Mann-Kendall Chloride Results for TPGW-19M .................................................. E.3-20 E.3-1.21 Mann-Kendall Chloride Results for TPGW-19D .................................................. E.3-21 xi

FPL Turkey Point RAASR Year 5 November 2023 List of Figures E.3-1.22 Mann-Kendall Chloride Results for TPGW-22S ................................................... E.3-22 E.3-1.23 Mann-Kendall Chloride Results for TPGW-22M .................................................. E.3-23 E.3-1.24 Mann-Kendall Chloride Results for TPGW-22D .................................................. E.3-24 E.3-1.25 Mann-Kendall Chloride Results for TPGW-L3-58................................................ E.3-25 E.3-1.26 Mann-Kendall Chloride Results for TPGW-L5-58................................................ E.3-26 E.3-2.1 Mann-Kendall Salinity Results for TPGW-1S ....................................................... E.3-27 E.3-2.2 Mann-Kendall Salinity Results for TPGW-1M ..................................................... E.3-28 E.3-2.3 Mann-Kendall Salinity Results for TPGW-1D ...................................................... E.3-29 E.3-2.4 Mann-Kendall Salinity Results for TPGW-2S ....................................................... E.3-30 E.3-2.5 Mann-Kendall Salinity Results for TPGW-2M ..................................................... E.3-31 E.3-2.6 Mann-Kendall Salinity Results for TPGW-2D ...................................................... E.3-32 E.3-2.7 Mann-Kendall Salinity Results for TPGW-12S ..................................................... E.3-33 E.3-2.8 Mann-Kendall Salinity Results for TPGW-12M ................................................... E.3-34 E.3-2.9 Mann-Kendall Salinity Results for TPGW-12D .................................................... E.3-35 E.3-2.10 Mann-Kendall Salinity Results for TPGW-15S ..................................................... E.3-36 E.3-2.11 Mann-Kendall Salinity Results for TPGW-15M ................................................... E.3-37 E.3-2.12 Mann-Kendall Salinity Results for TPGW-15D .................................................... E.3-38 E.3-2.13 Mann-Kendall Salinity Results for TPGW-17S ..................................................... E.3-39 E.3-2.14 Mann-Kendall Salinity Results for TPGW-17M ................................................... E.3-40 E.3-2.15 Mann-Kendall Salinity Results for TPGW-17D .................................................... E.3-41 E.3-2.16 Mann-Kendall Salinity Results for TPGW-18S ..................................................... E.3-42 E.3-2.17 Mann-Kendall Salinity Results for TPGW-18M ................................................... E.3-43 E.3-2.18 Mann-Kendall Salinity Results for TPGW-18D .................................................... E.3-44 E.3-2.19 Mann-Kendall Salinity Results for TPGW-19S ..................................................... E.3-45 E.3-2.20 Mann-Kendall Salinity Results for TPGW-19M ................................................... E.3-46 E.3-2.21 Mann-Kendall Salinity Results for TPGW-19D .................................................... E.3-47 E.3-2.22 Mann-Kendall Salinity Results for TPGW-22S ..................................................... E.3-48 E.3-2.23 Mann-Kendall Salinity Results for TPGW-22M ................................................... E.3-49 E.3-2.24 Mann-Kendall Salinity Results for TPGW-22D .................................................... E.3-50 E.3-2.25 Mann-Kendall Salinity Results for TPGW-L3-58 ................................................. E.3-51 E.3-2.26 Mann-Kendall Salinity Results for TPGW-L5-58 ................................................. E.3-52 xii

FPL Turkey Point RAASR Year 5 November 2023 List of Figures E.3-3.1 Mann-Kendall Tritium Results for TPGW-1S ....................................................... E.3-53 E.3-3.2 Mann-Kendall Tritium Results for TPGW-1M...................................................... E.3-54 E.3-3.3 Mann-Kendall Tritium Results for TPGW-1D ...................................................... E.3-55 E.3-3.4 Mann-Kendall Tritium Results for TPGW-2S ....................................................... E.3-56 E.3-3.5 Mann-Kendall Tritium Results for TPGW-2M...................................................... E.3-57 E.3-3.6 Mann-Kendall Tritium Results for TPGW-2D ...................................................... E.3-58 E.3-3.7 Mann-Kendall Tritium Results for TPGW-12S ..................................................... E.3-59 E.3-3.8 Mann-Kendall Tritium Results for TPGW-12M.................................................... E.3-60 E.3-3.9 Mann-Kendall Tritium Results for TPGW-12D .................................................... E.3-61 E.3-3.10 Mann-Kendall Tritium Results for TPGW-15S ..................................................... E.3-62 E.3-3.11 Mann-Kendall Tritium Results for TPGW-15M.................................................... E.3-63 E.3-3.12 Mann-Kendall Tritium Results for TPGW-15D .................................................... E.3-64 E.3-3.13 Mann-Kendall Tritium Results for TPGW-17S ..................................................... E.3-65 E.3-3.14 Mann-Kendall Tritium Results for TPGW-17M.................................................... E.3-66 E.3-3.15 Mann-Kendall Tritium Results for TPGW-17D .................................................... E.3-67 E.3-3.16 Mann-Kendall Tritium Results for TPGW-18S ..................................................... E.3-68 E.3-3.17 Mann-Kendall Tritium Results for TPGW-18M.................................................... E.3-69 E.3-3.18 Mann-Kendall Tritium Results for TPGW-18D .................................................... E.3-70 E.3-3.19 Mann-Kendall Tritium Results for TPGW-19S ..................................................... E.3-71 E.3-3.20 Mann-Kendall Tritium Results for TPGW-19M.................................................... E.3-72 E.3-3.21 Mann-Kendall Tritium Results for TPGW-19D .................................................... E.3-73 E.3-3.22 Mann-Kendall Tritium Results for TPGW-22S ..................................................... E.3-74 E.3-3.23 Mann-Kendall Tritium Results for TPGW-22M.................................................... E.3-75 E.3-3.24 Mann-Kendall Tritium Results for TPGW-22D .................................................... E.3-76 E.3-3.25 Mann-Kendall Tritium Results for TPGW-L3-58 ................................................. E.3-77 E.3-3.26 Mann-Kendall Tritium Results for TPGW-L5-58 ................................................. E.3-78 E.4-1 TPGW-1 Automated Salinity (March 2018 - September 2023) ............................. E.4-1 E.4-2 TPGW-2 Automated Salinity (March 2018 - September 2023) ............................. E.4-2 E.4-3 TPGW-12 Automated Salinity (March 2018 - September 2023) ........................... E.4-3 E.4-4 TPGW-15 Automated Salinity (March 2018 - September 2023) ........................... E.4-4 xiii

FPL Turkey Point RAASR Year 5 November 2023 List of Figures E.4-5 TPGW-17 Automated Salinity (March 2018 - September 2023) ........................... E.4-5 E.4-6 TPGW-18 Automated Salinity (March 2018 - September 2023) ........................... E.4-6 E.4-7 TPGW-19 Automated Salinity (March 2018 - September 2023) ........................... E.4-7 E.4-8 TPGW-22 Automated Salinity (March 2018 - September 2023) ........................... E.4-8 xiv

FPL Turkey Point RAASR Year 5 November 2023 Acronyms and Abbreviations ACRONYMS AND ABBREVIATIONS

ºC degrees Celsius

ºF degrees Fahrenheit 2D/3D 2-dimensional/3-dimensional AEM aerial electromagnetic AGF Aqua Geo Frameworks, LLC CA Consent Agreement CCS cooling canal system CO Consent Order CSEM continuous surface electromagnetic mapping RER Department of Regulatory and Economic Resources DIW deep injection well EDMS Electronic Data Monitoring System EM electromagnetic ET evapotranspiration ETo reference evapotranspiration FDEP Florida Department of Environmental Protection FPL Florida Power & Light Company ft foot/feet GPS global positioning system HEM helicopter electromagnetic HFZ high-flow zone HSI saline-hypersaline interface ID interceptor ditch LCI laterally constrained inversion m meter/meters MDC Miami-Dade County mg/L milligrams per liter mgd million gallons per day mL milliliter NMP Nutrient Management Plan ohm-m ohm meter PEST parameter estimation PFC primary field compensation pCi/L picocuries per liter ppt parts per thousand PSU practical salinity unit QAPP Quality Assurance Project Plan RAASR Remedial Action Annual Status Report RAP Remedial Action Plan RWS recovery well system SCADA Supervisory Control and Data Acquisition xv

FPL Turkey Point RAASR Year 5 November 2023 Acronyms and Abbreviations SCI spatially-constrained inversion SFWMD South Florida Water Management District SkyTEM SkyTEM Canada Inc.

SSMP Supplemental Salinity Management Plan TDS total dissolved solids TEM transient electromagnetic TEP thermal efficiency plan TN total nitrogen TP total phosphorus TPGW Turkey Point Groundwater Turkey Point Turkey Point Power Plant UFA Upper Floridan aquifer UIC underground injection control UICPW underground injection control production test well US 1 U. S. Highway 1 USEPA United States Environmental Protection Agency USGS United States Geologic Survey V1,V2 Version 1, Version 2, etc.

VDF variable density flow xvi

FPL Turkey Point RAASR Year 5 N ovem ber 2023 Ex ecutive Sum m ary EXECUTIVE

SUMMARY

Analyses of data collected through Year 5 of remediation document RWS operations are 1) halting the net westward migration of hypersaline groundwater; 2) intercepting, capturing, and containing hypersaline groundwater beneath the CCS; and 3) reducing the volumetric extent and salt mass of hypersaline groundwater west and north of FPL property. Salinity management actions have reduced the average annual salinity of the CCS to below 34 PSU since September 2022, eliminating the CCS as a source of hypersaline groundwater recharge. Remediation progress is exceeding the 2016 forecasted performance of the approved RWS; however, there is opportunity for system improvement. Recommendations for continued and enhanced RWS operations, monitoring, and reporting are proposed for agency review and approval covering remediation actions over the next 5 years, leading up to a Year 10 review.

The Florida Power & Light Company (FPL) has prepared this Remedial Action Annual Status Report (RAASR) to document the results of the Year 5 Recovery Well System (RWS) operation, in compliance with the monitoring and reporting objectives of the Miami-Dade County (MDC)

Consent Agreement (CA) and Florida Department of Environmental Protection (FDEP) Consent Order (CO). This RAASR also includes an evaluation of RWS capacity to continue removing hypersaline groundwater from the Biscayne aquifer and retracting the existing hypersaline plume eastward towards the L-31E canal.

FPL uses three primary tools to assess remediation progress: groundwater monitoring, continuous surface electromagnetic (CSEM) surveying using aerial electromagnetic (AEM) methods, and groundwater variable density flow and salt transport modeling. These tools, individually and collectively, demonstrate the RWS has reduced the rate of and halted migration of cooling canal system (CCS)-sourced hypersaline groundwater west and north of the CCS, reduced the volumetric extent and salt mass of the hypersaline plume, stopped discharges from the CCS that impair the reasonable and beneficial use of G-II groundwaters, and removed the hypersaline plumes influence on the saltwater interface.

Specifically, the following findings support these conclusions:

Since inception of the remediation system, approximately 29.72 billion gallons of hypersaline groundwater and 11.61 billion pounds of salt have been extracted from the Biscayne aquifer.

The average annual salinity in the CCS reached 34 PSU on September 23, 2022, and the annual rolling average has remained below 34 PSU since September 24, 2022, eliminating the CCS as a source of hypersaline recharge to groundwater and resulting in significant reductions in shallow groundwater salinity beneath the CCS.

ES-1

FPL Turkey Point RAASR Year 5 N ovem ber 2023 Ex ecutive Sum m ary

Most hypersaline wells have a statistically significant declining trend in salinity and chloride concentrations since the start of the RWS, with many of them showing new record low values in Year 5. Four wells are transitioning from hypersaline to saline, and two additional wells on the verge of making the same transition.

Revisions to the approach used to convert AEM bulk resistivity to chloride concentrations were implemented in this years survey to address year to year drift and uncertainty intrinsic to both AEM resistivity and lab chloride data. The results are more mathematically robust and are shown to reduce uncertainty from previous plume estimations while improving the mathematical confidence of the results. Despite these improvements, significant unresolved variance remains and that will be the focus of further evaluation in subsequent surveys.

Utilizing alternative methods for calculating hypersaline groundwater volumes resulting from technical discussions with MDC, AEM surveys evaluated over the first 5 years of RWS operations confirm statistically valid reductions have occurred to the volumetric extent of the hypersaline plume west and north of the FPL property, albeit to a lesser magnitude than calculated in Year 4.

The updated and calibrated Year 5 groundwater model, monitoring data, and AEM data show greater plume reductions have been achieved through Year 5 (and predicted to occur by Year 10) than were expected in 2016 when the RWS remediation was approved by the agencies.

In addition to record reductions in CCS salinity, record reductions in canal nutrients, algae, turbidity, and chlorophyll-a have been achieved along with commensurate improvement in biotic indicators, including American Crocodile nesting success.

FPL has eliminated CCS contributions to the existing hypersaline plume, and the RWS has halted expansion of the plume. Moreover, the existing hypersaline plume is reducing in volume, and the RWS has operated without negative impact on the environment. Despite remediation progress, the Year 5 model confirms the 2016 finding that while full retraction of the existing hypersaline plume to the L-31E canal is predicted to occur in shallow and intermediate model layers by 2028, full retraction to the L-31E canal along the base of the aquifer is not anticipated to occur after 10 years of RWS operation. Therefore, FPL evaluated alternatives to the approved RWS plan and recommends agency approval of Alternative 1, as described in Appendix I (increased withdrawal capacity and hardening). FPL will continue to operate the RWS as currently approved during agency review of FPLs proposal. FPL is considering the following actions:

Use test wells to evaluate the nature of AEM isolated lenses of hypersalinity in the southwest portion of the compliance area in layers 9 and 10, salinity along the base of the aquifer, and groundwater salinity in areas characterized by switching hypersaline voxels to better inform remediation progress along the western extent of the plume.

ES-2

FPL Turkey Point RAASR Year 5 N ovem ber 2023 Ex ecutive Sum m ary

Attempt to reduce uncertainty in AEM-based plume volume estimates by correlating AEM resistivity to salinity instead of chloride because salinity measurements vary less quarter-to-quarter than chloride data.

Continue monitoring CCS salinities and climate conditions and update/recalibrate the model with more data reflective of longer RWS operations. The longer period of RWS operation and consequent changes to salinities over a progressively larger area will help inform the model and increase its accuracy in simulating the effect of the RWS and forecasting longer-term performance.

ES-3

FPL Turkey Point RAASR Year 5 N ovem ber 2023 1. I ntroduction 1 INTRODUCTION FPL is submitting this Year 5 Remedial Action Annual Status Report (July 1, 2022, through June 30, 2023) on the status of remediation and progress in meeting the objectives of the MDC CA and FDEP CO. The remediation efforts have resulted in significant reduction in salt mass and the volumetric extent of hypersaline groundwater west and north of the FPL property over the last 5 years.

Additionally, multiple restoration and remediation activities outlined in the CA and CO have been completed, and FPL and has made substantial progress in implementing and completing activities that have resulted in tangible improvements within the CCS.

1.1 BACKGROUND

ON GROUNDWATER REMEDIAL SYSTEM 1.1.1 FDEP Consent Order - MDC Consent Agreement Florida Power & Light Company (FPL) submits this Year 5 Remedial Action Annual Status Report (RAASR) pursuant to paragraphs 17.b.iii and 17.d.v of the Miami-Dade County (MDC)

Department of Regulatory and Economic Resources (DERM) Consent Agreement (CA) and paragraphs 28, 29.c., and 33 of the Florida Department of Environmental Protection (FDEP)

Consent Order (CO).

FPL entered into the CA on October 7, 2015, and the CO on June 20, 2016. FPL agreed to conduct specific actions, including the remediation of hypersaline groundwater adjacent to the FPL Turkey Point Power Plant (Turkey Point). The specific objectives of the CA for groundwater remediation are to demonstrate a statistically valid reduction in the salt mass and volumetric extent of hypersaline water in groundwater west and north of FPLs property without creating adverse environmental impacts and to reduce the rate of, and ultimately arrest, migration of hypersaline groundwater. Hypersaline groundwater, as defined in the CO and CA, is groundwater with a chloride concentration greater than 19,000 milligrams per liter (mg/L).

A key objective of the CO is to cease discharges from the cooling canal system (CCS) that impair the reasonable and beneficial use of adjacent G-II groundwater to the west of the CCS.

The CO states that this objective will be accomplished by undertaking freshening activities as authorized in the Turkey Point site certification, by eliminating the CCS contribution to the hypersaline plume, by maintaining the average annual salinity of the CCS at or below 34 practical salinity units (PSU), by halting the westward migration of hypersaline water from the CCS, and by reducing the westward extent of the hypersaline plume to the L-31E canal within 10 years. These actions will remove the influence of discharged CCS water on the saltwater interface without creating adverse environmental impacts.

1-1

FPL Turkey Point RAASR Year 5 N ovem ber 2023 1. I ntroduction 1.1.2 Remediation Formulation, Alternative Evaluation, and Implementation Beginning in 2015, FPL initiated the evaluation and design of a recovery well system (RWS) capable of intercepting, capturing, containing, and retracting hypersaline groundwater west and north of the FPL property boundary in accordance with the requirements of the CA. To evaluate the performance of different remediation alternatives, FPL developed a high-resolution, variable density groundwater flow and transport model covering southeastern Miami-Dade County. The first version (V1), developed in 2016, was based on limited existing geologic and hydrologic data, including the results of an aquifer performance test conducted at the northwest corner of the CCS. There were no data at that time on how the Biscayne aquifer responded to groundwater extractions around Turkey Point; however, it was recognized that as more data were collected over time, the model would be updated and refined.

Fifteen groundwater remediation alternatives were identified in 2016 as part of remedial measure formulation and included no action, CCS freshening only, groundwater extraction wellfields at different locations, horizontal extraction wells, and saltwater toe injection. The alternatives were evaluated and ranked based on 11 different criteria that considered the following: hypersaline groundwater plume volume and mass reduction by Years 5 and 10 of remediation, hypersaline edge retraction toward the L-31E canal, retraction of the freshwater saltwater interface, wetland-surface water impacts, time to implement, ability to permit, and legal control of facilities.

Descriptions of the 15 alternatives considered in the model, the screening criteria, and the resulting scores for all alternatives were presented to the agencies on May 16, 2016, and formally submitted to MDC on May 28, 2016, and FDEP on July 20, 2016. Modeling showed none of the alternatives, including the preferred alternative (Alt-3D), were successful in retracting hypersaline groundwater at the base of the Biscayne aquifer to the L-31E canal by Year 10.

Subsequently, the model was extensively reviewed jointly by the South Florida Water Management District (SFWMD), FDEP, MDC, the United States Environmental Protection Agency (USEPA), and the University of Florida. Based on feedback from the peer review, revisions to the model were made. The performance of the preferred alternative was reassessed using the revised model, which confirmed the original finding that full remediation of hypersaline groundwater along the base of the Biscayne aquifer was not shown to be achieved by Year 10 of remediation. A Remedial Action Plan (RAP) was prepared for Alt-3D and submitted to the agencies for review on January 27, 2017. After obtaining all required environmental and well construction permits for the approved RAP, FPL initiated construction of the Alt-3D RWS, which includes 10 groundwater recovery wells, a conveyance pipeline system, and a deep injection well (DIW) more than 3,000 feet (ft) below the base of the Biscayne aquifer. Details regarding the recovery wells, pumps, controls, pipeline, and injection wells can be found in the Recovery Well Startup Report (FPL 2018a). The system was fully operable on May 15, 2018.

1.1.3 Monitoring/Assessment of Remediation Progress Due to the aerial extent of the remediation area, a three-pronged approach is used to assess the progress of remediation. This approach includes FPLs groundwater monitoring well network; 1-2

FPL Turkey Point RAASR Year 5 N ovem ber 2023 1. I ntroduction annual aerial electromagnetic (AEM) surveys, which provide more detailed spatial assessment of groundwater trends; and the annually updated and recalibrated density-dependent solute transport groundwater model. Each of these methods/tools inherently includes uncertainties, but they collectively provide a comprehensive and reliable assessment of remediation progress.

1.1.3.1 Monitoring Wells The monitoring well network enables the collection of groundwater samples from discrete high-flow zones in the Biscayne aquifer and continuous monitoring of salinity in wells with automated probes. Hourly automated salinity data provide a continuous record of saltwater concentrations within the discrete shallow, intermediate, and deep high-flow zones, while quarterly analytical results reflect chloride concentrations from these zones. In addition, annual induction logs provide a vertical profile of bulk conductivity, which provides insight to annual changes with depth at each well location. The induction logs show significant variations in measured bulk resistivity often occur over intervals less than 10 feet in wells. These changes are considered to be the result of changes in groundwater ionic strength combined with variations in aquifer lithology/porosity. However, reductions in bulk conductivity at specific depth intervals over several years are indicative of reductions in water salinity at those intervals.

An advantage of monitoring wells is the direct in situ sampling of groundwater, although there are uncertainties associated with the small sampling interval of the monitoring well compared to the aquifer thickness, the limited number of wells compared with the size of the study area, the analytic method and sample collection errors, and the associated uncertainty in the vertical and lateral extent of the aquifer area that is represented by any given monitoring well. Despite the inherent uncertainties associated with monitoring well networks, direct sampling is the most common and widely accepted method for assessing progress of groundwater remediation projects. Limitations associated with relying solely on monitoring wells are the size of the compliance area being monitored is so large (approximately 22 square miles) that many additional wells would be required, access to additional sites is difficult due to expansive wetlands in the area, and access to and installation of monitoring wells in wetlands would result in adverse impacts. In addition, the monitoring wells provide data at a specific location; therefore, changes in salinity/chloride concentrations in areas between wells which could be miles apart have to be estimated through interpolation and do not account for variability in the Biscayne aquifer.

Results from the groundwater monitoring are provided in Section 3 and Appendix B of this report, with additional data provided in FPLs electronic data management system (EDMS).

1.1.3.2 AEM Survey To provide a continuous three-dimensional (3D) assessment of the CCS hypersaline plume, bulk resistivity of the Biscayne aquifer is measured annually along prescribed flight lines across the Model Lands area west and north of the CCS via AEM survey methods. The resistivity data are acquired at 14 distinct depth intervals that span the thickness of the aquifer. The resistivity data are mathematically correlated to monitoring well chloride data to produce chloride concentration maps, cross-sections, and 3D representations of the plume for the 2018 base condition and 2023.

1-3

FPL Turkey Point RAASR Year 5 N ovem ber 2023 1. I ntroduction An advantage of using AEM is the vast number of measurements made during each survey (average of approximately 15,000) that provide the most comprehensive assessment of changes in groundwater quality without impacting environmentally sensitive lands. Drawbacks of the method include uncertainties associated with small changes in resistivity due to the sensitivity of the equipment, electromagnetic noise, small variations in calibration and equipment sensitivities, and mathematical uncertainties introduced in the process of translating bulk resistivity measurements to dissolved chloride concentration estimates (Appendix F).

FPL conducted a 2018 baseline AEM survey from March 31 to April 6, 2018, prior to the startup of the entire RWS. Annual RAASRs, which included results of the AEM surveys, were subsequently submitted beginning with the first-year report (Year 1) covering May 15, 2018, to May 31, 2019 (FPL 2019c), with the AEM survey conducted May 24-26, 2019. In year 2, collection of AEM survey data was delayed from the originally scheduled end of May 2020 time frame until September 2020 due to restrictions on international travel and health risks associated with the COVID-19 pandemic. This resulted in the Year 2 RAASR having 16 months of data and being submitted in two parts: groundwater monitoring data from June 2019 to September 2020 (FPL 2020a) and the Year 2 AEM survey (flown September 26-27, 2020) and groundwater model (FPL 2021a). The Year 3 report included groundwater monitoring data collected from October 1, 2020, to September 30, 2021, an updated groundwater model (V6), and the Year 3 AEM survey flown June 18-22, 2021 (FPL 2021b). In an effort to return to the pre-COVID 12-month annual remediation assessment schedule, the Year 4 report comprised data collected from July 2021 through June 2022, including the Year 4 AEM survey flown on May 19 and 20, 2022 (FPL 2022b). This time frame incorporated the June 2022 quarterly sampling event, which was used to establish the relationship with bulk AEM transient method resistivity measurements from the May 2022 AEM survey.

1.1.3.3 Modeling The variable density groundwater flow and transport model, originally developed in 2016 for the evaluation of remediation alternatives, including the approved RWS, has been updated and recalibrated annually since 2019 using data associated with RWS operations and input from independent peer reviews of the model. In each RAASR, the updated model has been used to assess movement of hypersalinity beneath, west, and north of FPL property, and to estimate plume remediation progress at Years 5 and 10, as required in the CO and CA. Details regarding the model updates, recalibration statistics, and the Years 5 and 10 remediation forecasts are covered in Section 5.

1.2 SCOPE OF THE REMEDIAL ACTION ANNUAL STATUS REPORT This Year 5 RAASR report includes the following:

Information collected from July 1, 2022, to June 30, 2023; although in some instances, analytical data from September 2023 have been incorporated into this report for the most updated trends 1-4

FPL Turkey Point RAASR Year 5 N ovem ber 2023 1. I ntroduction

Year 5 RWS operational summary, including analytical results from the RWS wells, salt mass and hypersaline groundwater removal, and operation run times

Data and assessment from monitoring wells in Year 5 and comparisons to baseline conditions and previous years

Year 5 AEM survey results, with comparisons between the 2023 AEM survey and the 2018 baseline AEM survey

An updated RWS groundwater model description and year 10 remediation forecast results

Status of activities related to management of the CCS and resulting improvements, including data through September 30, 2023

Appendices containing additional supporting information and data used in the report (Appendices A-H and J)

The Turkey Point Groundwater Remediation Project Year 5 Evaluation Report prepared pursuant to CA Condition 17.b.iii and CO Condition 20.c.v., including recommendations for modifications to the RWS and monitoring and reporting for agency review and approval (Appendix I)

Section 2 of the RAASR provides an overview of RWS operations, and it includes a summary of automated and analytical data from the recovery wells and the calculation of total salt removed by the RWS.

Section 3 of the RAASR provides automated data and/or analytical samples from up to 40 monitoring wells west and north of the CCS used to assess the progress of RWS remediation.

Year 5 data encompass the period from July 1, 2022, to June 30, 2023; chloride, field salinity, and automated salinity data for September 2023 have also been included to provide the most recent information on data trends. These data along with Year 1, Year 2, Year 3, and Year 4 data were used to evaluate changes and trends in groundwater quality from baseline conditions in March 2018 through September 2023 (67 months). The results were compared to data collected prior to RWS startup to identify changes likely related to RWS operations. Groundwater chloride contour maps for the shallow, middle, and deep monitoring well horizons augmented with AEM data are generated for Year 5 and compared with similarly prepared 2018 baseline contour maps to identify changes in the extent of hypersaline groundwater.

Section 4 of the RAASR includes the results of the Year 5 AEM survey, with comparisons to the baseline 2018 AEM survey to document changes to the extent and volume of the hypersaline plume within the CO/CA compliance boundary that have occurred since RWS operations began.

Section 5 of the RAASR contains documentation of the updated, recalibrated Turkey Point groundwater model with predictive model runs for year 10 of plume remediation.

1-5

FPL Turkey Point RAASR Year 5 N ovem ber 2023 1. I ntroduction Section 6 of the RAASR discusses findings observed in the CCS associated with salinity, nutrient, and thermal efficiency management actions.

Section 7 of the RAASR concludes with a summary of progress to date and recommendations for the next phase of remediation.

1.3 STATUS OF CONSENT AGREEMENT/CONSENT ORDER IMPLEMENTATION FPL is successfully implementing restoration and remediation activities outlined in the MDC CA and FDEP CO, resulting in significant reductions of hypersaline groundwater volume and improved CCS water quality and conditions.

The RAASR provides information on FPLs progress in meeting the groundwater remediation objectives of the CA and CO along with the status of meeting the additional requirements of these regulatory documents. The CA and CO consist of two categories of required actions: those with deadlines for completion that precede this report (e.g., design and construct an approved groundwater RWS) and ongoing/future actions (e.g., continuing implementation of CCS salinity, nutrient, and thermal efficiency management plans and groundwater remediation).

FPL has successfully completed all actions required to be completed prior to this report and is on track implementing all ongoing actions. A summary of all required actions of the CA and CO is included in Appendix A. Additional details pertaining to ongoing actions, including salinity, nutrient, and thermal management in the CCS, are further discussed in Section 6.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary 2 RECOVERY WELL SYSTEM YEAR 5 OPERATION

SUMMARY

2.1 HYPERSALINE EXTRACTION/DISPOSAL OPERATIONS The RWS operated 95.8% of the time during the reporting period; there were only 364 hours0.00421 days 0.101 hours 6.018518e-4 weeks 1.38502e-4 months (equivalent of 15.2 days) out of the year (4.2%) when the entire system was not operational. The majority of outages were related to system enhancements, repairs, and maintenance activities, and during the CSEM survey.

FPL operates 10 recovery wells to extract up to 465 million gallons per month (annual average of 15 mgd) of hypersaline groundwater, preferentially along the base of the Biscayne aquifer. The extraction wells are cased to the lower high flow zone of the Biscayne aquifer (FPL 2018a),

allowing hypersaline water to be withdrawn along the base of the plume. As the extraction wells are pumped, hypersaline groundwater from beneath the CCS and west and north of the plume flows laterally toward the points of withdrawal. As hypersaline water is removed, the plume shrinks both vertically and laterally with adjacent lower-salinity groundwater replacing the area formerly containing hypersaline groundwater. The extraction of hypersaline groundwater from the lower extent of the Biscayne aquifer along the western margin and north of the CCS accomplishes the objectives listed below:

Reduces the salt mass and volumetric extent of hypersaline groundwater west and north of the CCS. The retraction of the hypersaline plume is accomplished primarily by direct extraction of hypersaline groundwater, which increases the natural seaward groundwater flow gradient eastward into the RWS capture zone, and secondarily by natural dilution and dispersion of hypersaline water with the lower salinity waters in Biscayne aquifer.

Creates a hydraulic barrier that intercepts and contains the westward and northward migration of hypersaline groundwater from the CCS. RWS operations extend the hydraulic barrier effect of the interceptor ditch (ID) operation in the upper portion of the Biscayne aquifer to the base of the aquifer.

Decreases groundwater salinity and mass beneath the CCS, which reduces the driving force that contributed to lateral movement away from the CCS and which is a component of halting the westward migration of hypersaline groundwater from the CCS.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary The hypersaline groundwater is pumped from each recovery well into a collection system that consists of an approximately 9-mile-long pipeline that is routed to a DIW located near the center of the CCS for disposal.

The DIW is a 24-inch-diameter permitted underground injection control (UIC) non-hazardous Class I industrial wastewater disposal well (Permit No. 0293962-004-UO/1I) constructed to a depth of 3,230 ft below ground surface into the regionally confined boulder zone. Near The deep injection well.

the end of Year 1, the permitted operating capacity of the DIW was increased from 15.59 mgd to 18.64 mgd (Permit Modification No. 0293962-005-UO/MM) to accommodate additional remediation flows.

The Consumptive Use Permit from SFWMD authorizes an RWS annual withdrawal allocation of 5,475 million gallons (15 mgd) and a maximum monthly allocation of 465 million gallons from RWS extraction wells 1 through 10. In early 2020, two underground injection control production test wells (UICPWs) (UICPW-1 and UICPW-2), co-located with the DIW and constructed to the base of the Biscayne aquifer in a similar manner as the recovery wells, were activated with a rate of approximately 3 mgd each to remove hypersaline groundwater from beneath the CCS. This extracted hypersaline water is disposed in the DIW along with the RWS-extracted hypersaline water, using the DIW UIC permits injection rate limit.

The groundwater extraction wells are controlled by a Supervisory Control and Data Acquisition (SCADA) system that controls the operation of all wells, has the capability to monitor and regulate individual well withdrawal rates, and maintains real-time-assigned total system extraction capacity in the event of individual well fluctuations. This system enables operators to maintain compliance with groundwater withdrawal and disposal permit limits. Flow pumped from each RWS well is measured by totalizers, and the combined flow down the DIW is also measured by a totalizer. All RWS and DIW flow meters were checked, calibrated, and certified in June 2023 as part of the annual calibration process.

Overall, the RWS operated 95.8% of the time from July 1, 2022, to June 30, 2023 (2% increase in run time over the previous period), with only 364 hours0.00421 days 0.101 hours 6.018518e-4 weeks 1.38502e-4 months (equivalent of approximately 15.2 days) over the year in which the entire system was turned off, primarily related to system enhancements and repairs, maintenance activities, and during the continuous surface electromagnetic mapping (CSEM) survey. There were four outages that lasted more than a day which included the following:

December 26, 2022, 6:00, to December 30, 2022, 13:00. System shut off due to low flow caused by piping corrosion and leakage. The failed pipe section was replaced, and the system was restarted by the weeks end.

May 16, 2023, 8:00, to May 19, 2023, 14:00. The whole system was turned off to reduce electrical noise during the CSEM survey.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary

June 2, 2023, 11:00, to June 5, 2023, 11:00. The system shut off due to low flow caused by multiple pumps out of service for repairs.

June 24, 2023, 19:00, to June 26, 2023, 8:00. The system shut off due to power outage over the weekend.

In addition to system-wide RWS outages, individual extraction wells shut down for various reasons, including enhancements (installing sand deflectors and additional pump stages), repairs, refurbishment, calibration tests, or preventive maintenance. In these cases, the SCADA system immediately adjusted pumping of the remaining operational wells to continue authorized system total monthly withdrawal rates. Preventive maintenance measures, which are necessary for effective long-term operation of the system, included replacing ductal iron wellhead components, excessively worn pump components, and electronic operational components that reach the end of their projected operational life, and periodically pulling pumps and motors for rehabilitation based on manufacturers recommendations. Operational run times for each of the RWS wells are shown graphically on Figure 2.1-1. RWS-7 was out of service more frequently compared to the other wells as excessive sand was being pulled into the pump causing damage to the system.

FPL tried several approaches to address the issue with sand deflectors installed on the pump intake, which ultimately addressed the problem. Sand deflectors have now also been installed on additional wells as a proactive measure.

Figure 2.1-1. Operation of RWS in Year 5 (Pumping with More than 4 Hours of Daily Flow) 2-3

FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary 2.2 RECOVERY WELL SYSTEM MONITORING RESULTS AND HYPERSALINE GROUNDWATER/SALT MASS REMOVED During the reporting period, FPLs groundwater remediation actions removed approximately 6.29 billion gallons of groundwater with a combined average chloride concentration of approximately 26,000 mg/L that contained 2.37 billion pounds of salt. Since inception of the remediation system, approximately 29.72 billion gallons of groundwater with a combined average chloride concentration of 27,400 mg/L and 11.61 billion pounds of salt have been extracted from the Biscayne aquifer.

Automated flow, salinity, total dissolved solids (TDS), and water elevation data were continuously recorded from each RWS extraction well. Water quality samples were collected from each RWS well monthly and were analyzed for chloride along with field parameters.

Pursuant to execution of CA Amendment 2 on August 20, 2019, quarterly sampling of RWS nutrients was implemented in September 2019. All sampling/monitoring was conducted in accordance with the SFWMD approved FPL Quality Assurance Project Plan (QAPP) (FPL 2013). Water quality data referenced in this RAASR are available in Microsoft Excel tables on the FPL Turkey Point EDMS database (https://www.ptn-combined-monitoring.com).

Automated data for all 10 RWS wells and the two UICPW wells are shown in Appendix B.

Analytic data are shown in Appendix C, including the field parameters and additional analytes (i.e., nutrients), field sampling logs, data qualifiers, and quality assurance samples. Data usability summaries for the events are provided in Appendix D. Level 4 laboratory reports from the FPL Central Laboratory can be found on FPLs EDMS at https://www.ptn-combined-monitoring.com.

Table 2.2-1 shows a summary of the chloride values for all recovery wells. Chloride values in most of the wells reflect hypersaline conditions, ranging between 21,400 mg/L and 30,900 mg/L in Year 5. The only exception was RWS-1 where all monthly chloride concentrations were less than 19,000 mg/L and ranged between 14,800 mg/L and 18,100 mg/L (Figure 2.2-1). RWS-1 started to frequently have chloride concentrations less than 19,000 mg/L in July 2019.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary Table 2.2-1. RWS Chloride Monitoring Results (mg/L)

Sample ID 2022 2023 Average Current Reporting Previous July Aug Sept Oct Nov Dec Jan Feb Mar Apr May June Period Year (7/1/21-(7/1/22- 6/30/22) 6/30/23)

RWS-1 16500 17500 15600 14700 16600 15600 14800 16100 17100 15900 16200 18100 16225 16933 RWS-2 24000 23200 23500 22600 23400 21600 21800 23100 23300 21400 22600 21700 22683 23933 RWS-3 28000 25800 26700 25400 25400 24100 23500 25200 25500 23600 24300 24100 25133 26717 RWS-4 30900 28600 29600 29000 29200 27200 27100 29500 29200 26800 27600 27800 28542 29700 RWS-5 30800 28900 30100 29500 28000 27700 26500 28700 29200 27100 28300 28300 28592 29408 RWS-6 30000 28400 29500 27600 28500 26600 26800 28700 28800 26100 27700 28100 28067 28592 RWS-7 29600 27400 29300 28400 27900 26300 NA 29400 28700 NA NA NA 28375 28150 RWS-8 30500 29400 30600 28700 29100 26900 26900 29200 29300 27600 28600 28400 28767 29483 RWS-9 29700 28300 29700 29000 28000 26100 26600 28700 28900 27000 28000 28100 28175 28492 RWS-10 26400 25200 26000 24600 24600 25700 23100 25500 24600 23800 24900 25200 24967 25533 UICPW-1 NA NA 29100 NA NA NA NA NA NA NA NA NA 29100 29520 UICPW-2 28700 27600 NA 26200 25400 NA 27500 NA 27500 25300 NA 26400 26825 29800 Key:

NA = not available/no pumping.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary Figure 2.2-1. RWS Chloride Results (mg/L)

A Mann-Kendall trend analysis conducted on each extraction well for the reporting period showed two wells (RWS-2 and RWS-3) with a declining trend. The other wells showed no trend over the past year. Over a longer term, analysis of monthly data from May 2018 through June 2023 show statistically significant gradual declines in chloride concentrations in all the RWS wells.

This gradual reduction in salinity of the RWS wells was documented in early modeling of the RWS (Tetra Tech 2016). The design of the remediation system considers the fluid density of the plume, which is why the extraction wells are open to the base of the aquifer (i.e., dense hypersaline groundwater will naturally sink toward extraction points along the base of the aquifer). Accordingly, it is expected that the salinity levels of the extracted water from the RWS wells will remain elevated for an initial period while the thickness of the plume diminishes. As the vertical and lateral extent of the hypersaline plume diminishes over long-term operation of the RWS, larger portions of lower salinity groundwater from above the extraction horizon mix with hypersaline water moving laterally along the base of the Biscayne aquifer, resulting in a gradual lowering of the extracted water salinity.

The majority of changes since start-up are modest with both chloride and salinity reductions ranging between 5% and 13%. However, RWS-1 and RWS-2 have exhibited greater reduction since the first year of operation: both average chloride and salinity values are now approximately 25% lower and 17% lower than at inception at RWS-1 and RWS-2, respectively. Both of these RWS wells are located on the north side of the CCS where the plume is thinner, and CSEM data shows that the plume has diminished significantly in this area since remediation began in 2018.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary Table 2.2-2 shows the monthly volume of groundwater pumped from each recovery well Volume Salt during the reporting period. In seven of the Time Period (billion (billion months, the withdrawal amounts were within gallons) pounds) 99% of the total maximum monthly allocation of July 1, 2022 -

465 million gallons per the Consumptive Use June 30, 2023 6.29 2.37 Permit and three of the months were within 97%. FPL focused efforts on maximizing the May 15, 2018 -

29.72 11.61 June 30, 2023 monthly allowed withdrawals while staying within the limits of the Consumptive Use Values shown are for total water and salt mass Permits annual withdrawal of 5.475 billion extracted for the reporting period and the total since startup through June 2023.

gallons. From July 1, 2022, to June 30, 2023, approximately 5.43 billion gallons of water were extracted from the RWS and disposed of via the DIW and was 99% of the allowed annual withdrawal. An additional 0.86 billion gallons of hypersaline groundwater were extracted in Year 5 from the UICPW wells in the middle of the CCS (Appendix B, Table B.2-1), for a total of 6.29 billion gallons of hypersaline groundwater removed from the Biscayne aquifer from July 1, 2022, to June 30, 2023. Since the start-up of the RWS in May 2018, 29.72 billion gallons of hypersaline groundwater have been removed.

Table 2.2-2. Monthly RWS-1 through RWS-10 Volume Withdrawn (MG)

ID 2022 2023 Total Current Reporting July Aug Sept Oct Nov Dec Jan Feb Mar Apr May June Period (7/1/22-6/30/23)

RWS-1 36.4 44.5 44.7 46.5 33.8 41.6 46.0 45.9 49.0 50.6 17.6 29.3 485.8 RWS-2 45.7 45.9 44.9 47.2 37.4 41.7 52.2 46.4 49.5 51.9 58.1 50.6 571.5 RWS-3 46.7 46.7 45.4 47.2 49.3 41.8 52.2 45.8 49.4 51.9 58.7 53.1 588.3 RWS-4 46.1 46.0 45.6 44.5 49.3 41.7 52.2 45.6 49.0 50.8 54.5 37.6 563.0 RWS-5 45.8 46.9 46.0 45.4 49.2 41.7 52.2 45.2 49.0 51.2 56.0 48.9 577.4 RWS-6 45.7 46.8 45.7 47.1 49.1 41.8 52.2 45.7 49.0 50.6 53.1 46.2 573.0 RWS-7 46.7 45.9 45.0 45.3 47.9 23.2 0.0 50.4 20.9 0.0 0.0 10.4 335.7 RWS-8 46.7 46.6 45.2 46.8 48.6 41.7 52.2 46.5 50.1 52.2 59.7 54.6 591.0 RWS-9 46.6 46.8 45.7 47.2 49.1 41.7 52.2 46.8 49.6 50.6 53.3 48.0 577.5 RWS-10 45.2 47.5 46.5 47.2 48.9 41.8 52.2 46.2 49.1 50.0 52.1 45.3 571.9 Monthly Total 451.5 463.5 454.6 464.4 462.5 398.6 463.8 464.6 464.7 459.8 463.2 424.0 5435.2 Table B.2-1 of Appendix B shows the weekly water volume pumped, the automated weekly TDS values, and the associated amount of salt mass removed on a weekly basis for each recovery well, which is calculated in accordance with paragraph 29.f of the FDEP CO. Salinity data is provided with the TDS values for reference purposes because most readers are familiar with salinity. The salt mass values were based on automated flow and TDS data, and the values were then summed for daily and weekly salt mass removal. The TDS value is calculated from specific conductance using a preprogrammed conversion factor of 0.64 (based on empirical data from monitoring wells TPGW-11D and TPGW-13D from 2010-2016). The equation for salt mass removal is as follows:

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary gallons g mg liters Flow min x TDS L x 1,000 g x 3.7854 (gallon)

Salt mass removed (lbs/day) = mg 1,440 ( )

453,592.37 (lbs)

The total amount of salt mass removed varies since the pumping rates, run time, salinity, and TDS differ among wells and/or over time. In Year 5, approximately 2.01 billion pounds of salt were removed from the RWS wells (Appendix B, Table B.1-1) and 0.36 billion pounds for UICPW-1 and UICPW-2 (Appendix B, Table B.2-1), resulting in 2.37 billion pounds removed in the reporting year. Combined with salt mass removed in previous reporting periods, 11.61 billion pounds of salt have been removed from the Biscayne aquifer from May 15, 2018, to June 30, 2023.

2.3 RECOVERY WELL SYSTEM DRAWDOWN ASSESSMENT Water table drawdown from RWS operations continues to be negligible (less than 0.10 ft) in Year 5, consistent with previous observations when RWS pumping is occurring.

In the 2019 RAASR (FPL 2019c), FPL determined that the drawdown solely from RWS pumping was approximately 0.11 ft, and the combined drawdown with the RWS and ID was approximately 0.25 ft at TPGW-15S, which is located approximately 710 ft from RWS-3 and just west of the ID. The drawdown in the other depth intervals and at TPGW-1 was of similar magnitude. This amount of drawdown in the shallow portion of the Biscayne aquifer is considered negligible and is not considered harmful to wetlands or water resources. The SFWMD regulates drawdown impacts to wetlands and water resources. SFWMD water use rule criteria limit cumulative drawdowns beneath seasonally inundated wetlands to 1 ft during 1 in 10-year drought conditions and maximum authorized withdrawals (SFWMD 2015). Drawdowns that exceed the thresholds are considered harmful to wetlands and water resources. Based on the measured drawdowns of the combined impacts of the RWS and ID operations, the combined withdrawals are negligible.

Subsequently, in the Year 2 assessment presented in the 2020 Part 1 RAASR (FPL 2020a), FPL confirmed the above findings of negligible drawdown of 0.10 ft at TPGW-1S and TPGW-15S from solely RWS operations as there was no time during the reporting period when the RWS was turned off and the ID pumps were operating.

For Year 3 of operation, and similar to the previous years, several periods were selected when the RWS wells near TPGW-1 and TPGW-15 were turned off to allow the groundwater to stabilize when there was little to no rainfall (several tenths of an inch) that could mask drawdown. The results supported previous findings of a combined drawdown of approximately 0.25 ft at TPGW-1S and TPGW-15S when RWS and ID pumps are both operational (FPL 2021b).

In Year 4, there was one short period of three days when the RWS pumps near TPGW-1 and TPGW-15 were off, and rainfall totals were less than several tenths of an inch 2-8

FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary (March 14-17, 2022). The results showed changes in groundwater levels in TPGW-1 and TPGW-15 of less than 0.10 ft when the RWS wells are turned off and on (FPL 2022b).

Additionally, a review of water levels in TPGW-2 on the same dates of March 14-17 (when the entire system was shut down) indicated changes only in the hundredths of a foot in response to RWS operation. There were no times during the reporting period when the RWS was turned off and the ID pumps were operating. ID pumping was triggered only four times (seven days total) during Year 4, which limited the opportunity to assess the combined drawdown effect of ID and RWS operations when both systems were turned off and on. However, since drawdown of water levels in TPGW-1 and TPGW-15 during limited ID operation in April 2022 ranged from 0.10 to 0.20 ft, it is reasonable to conclude the combined influence of RWS and ID pumping on water levels at TPGW-1 and TPGW-15 is still approximately 0.25 ft.

In Year 5, there was only one period (June 2-5, 2023) where the RWS pumps near TPGW-1S and TPGW-15S (RWS-2 and RWS-3) and pumps near TPGW-2S (RWS-7 and RWS-8) were off for consecutive days to allow sufficient time to potentially observe the rebound in water levels and then the effect of restarting the RWS pumps. Similar to previous years, the results showed changes in groundwater levels in TPGW-1S and TPGW-15S of less than 0.10 ft when the RWS wells were turned off and on, and in the hundredths of a foot at TPGW-2S when the associated wells were turned off and on. Conditions to observe water level changes were not ideal as it rained more than 0.5 inch from June 2-5, 2023. Since water level changes due to RWS operations have historically been small, the full effect of RWS pumping can be masked by rainfall. ID pumping was triggered by only three short-term events (eight days total for a combined 133 hours0.00154 days 0.0369 hours 2.199074e-4 weeks 5.06065e-5 months ) during this reporting year, which limited the opportunity to assess the combined drawdown effect of ID and RWS operations when both systems were turned off and on. Regardless, there was nothing observed in Year 5 that would indicate anything different from what has been reported previously.

The impacts of the RWS operations on L-31E stage levels continue to be indiscernible (i.e., in the hundredths of a foot) when the pumps are turned off and on. Changes in water levels at nearby L-31E surface water canal sites TPSWC-1, TPSWC-2, and TPSWC-3 are within the range of normal fluctuations due to typical minor meteorological influences (e.g., wind), and do not appear to be a result of RWS operations.

A review of shallow groundwater levels over a longer term indicate positive effects of RWS operations as water elevations are increasing while the salinity/density of the groundwater decreases. This is most evident in wells closest to the RWS, such as TPGW-1S, TPGW-2S and TPGW-15S, that were initially hypersaline, but following RWS start-up, transitioned to non-hypersaline. Unless there are density changes, the historical difference in elevation between the shallow and intermediate and the shallow and deep wells remain relatively consistent. This applies to each of the FPL monitoring well clusters. When there is a rain event and the shallow well rises a certain amount, the intermediate and deep wells increase the same amount, to within hundredths of a foot. Where there is a drought, the amount of change in a well cluster is typically within hundredths of a foot.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary Over an extended period, without any stratification in the well or density changes at the screened interval, the differences in elevation between the shallow, intermediate, and deep wells in a cluster remain relatively consistent. Figure 2.3-1 shows water elevations for all three wells at TPGW-1, with the groundwater elevation at TPGW-1S increasing relative to TPGW-1M and TPGW-2M since RWS operations began. The salinity at TPGW-1S has dropped considerably, while the decline in salinity in the intermediate and deep wells are still modest. Additionally, in Figure 2.3-1, the water elevation at TPGW-1M is beginning to rise higher than at TPGW-1D as the salinity/density at TGW-1M is beginning to decline more rapidly.

Figure 2.3-1. Groundwater Elevation and Salinity at TPGW-1 Well clusters at TPGW-2 and TPGW-15 show the same phenomena with the shallow water elevations increasing as RWS operations progress relative to intermediate and deep wells in response to less dense groundwater in the shallower portion of the aquifer. Figure 2.3-2 shows groundwater elevations since 2010 at TPGW-1S and TPGW-5S, with the latter well, which has always been fresh, located several miles west of the RWS. While both wells exhibit seasonal patterns and the influence of drought and above-average rainfall years, the time series graphic clearly shows how the water elevation at TPGW-1S has risen relative to TPGW-5S since RWS operations began.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 2. Recovery W ell System Year 5 Operation Sum m ary Figure 2.3-2. Groundwater Elevation at TPGW-1S and TPGW-5S 2.4 INTERCEPTOR DITCH OPERATIONS FPL has reviewed ID operations in conjunction with RWS operations on multiple occasions in accordance with paragraph 17.a.iii of the CA. FPL has presented this information at various times, including in a meeting with DERM on May 16, 2016, in a letter to DERM dated May 23, 2016, in a presentation to DERM, FDEP, and SFWMD on May 19, 2017, in the RWS Start-Up Report (FPL 2018a), subsequent quarterly status reports (FPL 2018b, FPL 2019a, FPL 2019b),

as well as in FPLs Annual Monitoring Reports (FPL 2012, FPL 2016a, FPL 2017, FPL 2018c, FPL 2019d, FPL 2020b, FPL 2021c, FPL 2022a, FPL 2023a). The assessment of data showed the effectiveness of the ID in restricting westward migration of CCS groundwater into the upper portion of the Biscayne aquifer, into wetlands west of the CCS, and into the L-31E canal. In addition, the findings demonstrated a lack of harmful impacts to groundwater levels, wetlands, and other water resources in the area as further described in the reports referenced above.

In February 2023, FPL proposed to field test an alternative Interceptor Ditch Operating Procedure (IDOP) that could reduce the amounts of pump operations to below historic levels.

This field test was driven by the effectiveness of the RWS operations in preventing westward migration of groundwater from beneath the CCS and a desire by the Agencies to limit ID operations when possible. The SFWMD approved the test protocol on February 27, 2023, which relies on using salinity as a trigger in most of the ID instead of water levels for ID pumping (FPL 2023a). With the implementation of the text protocol at the end of February 2023 through May 2023, no pump operations were triggered when using salinity as a trigger; but they would have been triggered on multiple days during that same period if stage criteria were used. Based on an initial assessment of the ID test procedure (FPL 2023a), reliance on salinity as the trigger resulted in less ID pumping while continuing to constrain westward migration of saline groundwater from the CCS in the shallow portion of the Biscayne aquifer.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data 3 GROUNDWATER MONITORING DATA Groundwater monitoring to assess RWS performance was conducted on 37 wells west and north of the CCS. Most hypersaline wells have a declining trend since the start of the RWS and many of them show the lowest value on record in Year 5, with additional lows in September 2023. The monitoring well results combined with the area wide CSEM survey and modeling results provide a robust assessment of changes that are analyzed across the entire landscape west and north of the CCS.

3.1 GROUNDWATER MONITORING There are 40 monitoring wells used to help assess the progress of remediation (Figure 3.1-1).

Eleven of those wells, comprising well clusters TPGW-2, TPGW-15, TPGW-17 (three wells per cluster) plus single wells TPGW-L3-58 and TPGW-L5-58, are located between the CCS and L-31E canal outside a designated compliance boundary. These wells are used to monitor the progress of remediation near the hypersaline source area as the reduction of salinity in this zone helps reduce the driving head associated with more dense saltwater. The remaining 29 wells, comprising well clusters TPGW-1, TPGW-4, TPGW-5, TPGW-6, TPGW-12, TPGW-18, TPGW-19, TPGW-22, TPGW-23 (three wells per cluster) plus individual wells TPGW-G21-58 and TPGW-G28-58, are located west of the L-31E canal and north of the CCS in the compliance zone. In the compliance zone, there are 11 remaining hypersaline monitoring wells. Monitoring sites TPGW-4, TGPW-5, TPGW-6, TPGW-G21, and TPGW-G28 are located west of the hypersaline groundwater plume. These wells provide information on how RWS operations influence groundwater salinity near the GII-GIII potable groundwater interface.

For Year 5, groundwater samples were collected for laboratory analysis in September 2022, December 2022, March 2023, and June 2023. Samples were also collected in September 2023, and a subset of the data (chloride and salinity) is presented in this report to provide the most updated information on changes in water quality and trends.

The monitoring horizons for the 3-cluster wells at site TPGW-22 were established by MDC in 2020. Data from the TPGW-22 monitoring site has been collected since February 16, 2021.

Monitoring wells at TPGW-23 were installed by FPL in 2022 as requested by MDC, with data being collected since August/September 2022.

Samples for all events were collected at discrete screen intervals from the well clusters (i.e.,

shallow, intermediate, and deep intervals), except for the historic L and G series, which are continuously screened wells where samples were collected at 18 ft and 58 ft below the top of casing, unless noted otherwise. Samples from the groundwater clusters were collected using dedicated tubing and per the methods outlined in the QAPP (FPL 2013, 2023b) and FDEP 3-1

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Standard Operating Procedures. To aid in the assessment of the RWS, field parameters (i.e.,

temperature, specific conductance, salinity, density) were measured, and samples from each of the monitoring wells were sent for laboratory analysis of TDS, chloride, and tritium.

In most instances, the data show that the monitoring wells that were or still are hypersaline have lower values this reporting period compared to the baseline values in March 2018. A summary of the Year 5 quarterly chloride, field salinity, and tritium results are included in Tables 3.1-1, 3.1-2, and 3.1-3, respectively, along with baseline results for comparison. September 2023 results for chloride and field salinity are also included in Tables 3.1-1 and 3.1-2, but the September 2023 tritium data were not available at the time of report preparation. Note that March 2018 chloride values for TPGW-19M and TPGW-19D may be biased high, and values for TPGW-12M may be biased low; but the values are deemed usable. These results help gauge the progress of remediation, and the chloride data are used to convert bulk resistivity to chloride estimates for CSEM surveys and groundwater modeling updates. Select time-series graphs based on quarterly chloride, salinity, and tritium data from March 2018 (baseline) through September 2023 are provided in Section 3.2 and/or Appendix E which show the extent of change since RWS startup in the majority of the wells. Note that in the first year of monitoring, chloride samples were collected weekly for the first month of operation and monthly for the first quarter; data were presented in the 2019 RAASR (FPL 2019c). Chloride trend analyses conducted on monitoring data collected since RWS startup are based on quarterly data (i.e., early weekly and monthly values are not included) to avoid sample frequency biases.

In addition to analytical data, all the monitoring wells, except TPGW-L3, TPGW-L5, TPGW-G21, and TPGW-G28, are equipped with automated probes that record specific conductance, salinity, and water levels at 1-hour intervals. With the exception of recently installed site TPGW-22, automated data have been recorded since at least April 2018, with several well clusters (TPGW-1, TPGW-2, and TPGW-12) having data that extends back to 2010. For TPGW-22, automated probes were deployed in February 2021. Appendix E shows time-series of average weekly salinity graphs of select wells from the start of RWS monitoring where the entire well cluster at one or more depths have hypersaline groundwater.

Nearly all the analytical and automated data for Year 5 meet the data quality objectives of the QAPP (FPL 2013). Aside from a few sample results, all analytical monitoring well data are usable and exceed the QAPP completeness goal of 90%. Collectively, automated monitoring well water quality data and water level data are over 97% complete in Year 5. Nearly all parameters (i.e., specific conductance, salinity, temperature, and water elevations) in each well are over 95% complete, with the most notable exceptions being specific conductance at TPGW-22M and TPGW-22D showing percent completeness being closer to 80% due to probe issues.

There also appears to be continued stratification observed in TPGW-22S and TPGW-22M where the density of water in the casing may be lower than the density of the water at the screened interval. This can result in water elevation readings that, while accurate, may not fully represent freshwater head equivalents if they were to be calculated.

Occasionally, with the automated data, there are small offsets that occur in salinity following a cleaning and calibration event or when a probe is swapped out. These offsets may be the result 3-2

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data of slight but acceptable drift in the probe, variation in range of acceptable calibration accuracy, or differences in readings from two different probes. In most instances the data is usable but can influence trends, particularly if the overall trend change is small or the time period being assessed is short.

Figure 3.1-1. RWS and Monitoring Wells West and North of the CCS Used in the Assessment of the RWS 3-3

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Table 3.1-1. Monitoring Well Baseline and Year 5 Quarterly (Sept 2022 to June 2023) and September 2023 Chloride Concentration Data Baseline Additional Chloride Year 5 Chloride (mg/L)

Date Quarter (mg/L) 03/2018 09/2022 12/2022 03/2023 06/2023 09/2023 Wells Between CCS and L-31E Canal Near Hypersaline Source TPGW-2S 24800 15600 15400 14700 15200 11300 TPGW-2M 29500 30500 28900 26900 28600 26500 TPGW-2D 31300 31300 29900 27400 30200 29000 TPGW-15S 20100 11200 12900 14600 8910 858 TPGW-15M 30000 23700 22200 22400 23000 19500 TPGW-15D 28800 30900 28800 27600 29200 28300 TPGW-17S 24900 21900 20200 20300 20900 20700 TPGW-17M 29300 26400 25600 25600 25100 24700 TPGW-17D 28600 28100 27000 25500 27100 26500 TPGW-L3-18 2030 1350 159 409 151 140 TPGW-L3-58 31400 30300 29500 29700 29000 27000 TPGW-L5-18 1290 213 141 312 81.2 58.0 TPGW-L5-58 29500 27500 26800 27600 29100 26100 Compliance Zone Wells TPGW-1S 19400 4540 9450 9830 9210 2310 TPGW-1M 27700 24600 24500 24000 22900 20900 TPGW-1D 28500 28300 27400 28100 27100 26500 TPGW-4S 2280 1680 1790 2310 2080 717 TPGW-4M 15100 15300 15000 15100 15600 14600 TPGW-4D 14800 16200 15200 14900 16100 15600 TPGW-5S 164 163 145 132 133 138 TPGW-5M 11700 9760 9570 9000 8640 7160 TPGW-5D 13100 13800 13600 13900 13900 12900 TPGW-6S 313 315 240 263 264 292 TPGW-6M 7970 9430 8220 8160 8540 8350 TPGW-6D 8670 9980 8360 8350 8750 8620 TPGW-12S 16500 19800 16900 18300 19500 18100 TPGW-12M 20900* 20800 19700 20700 20400 20100 TPGW-12D 24000 26200 25100 25600 26800 25500 TPGW-18S 14200 2130 2110 2040 2150 1410 TPGW-18M 25200 22600 22700 21200 21800 21400 3-4

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Baseline Additional Chloride Year 5 Chloride (mg/L)

Date Quarter (mg/L) 03/2018 09/2022 12/2022 03/2023 06/2023 09/2023 TPGW-18D 26400 23300 22800 21400 22700 21500 TPGW-19S 1830 647 846 756 941 781 TPGW-19M 26000* 19000 18800 19200 19400 18800 TPGW-19D 26800* 23900 22300 23200 23700 23200 TPGW-22S NA 16100 15600 15600 16500 15600 TPGW-22M NA 21700 20700 22000 21800 20600 TPGW-22D NA 21900 20800 21100 21200 21000 TPGW-23S NA 9050 10600 10900 11700 10500 TPGW-23M NA 22300 20900 21500 22600 23300 TPGW-23D NA 24000 22700 23500 24100 22200 TPGW-G21-18 49.2 37.3 36.0 49.2 52.9 43.0 TPGW-G21-58 7210 7000 6690 6880 6830 6470 TPGW-G28-18 693 395 288 298 298 266 TPGW-G28-58 14200 14800 14600 15100 15400 14200 Notes:

1. Laboratory results are reported with three digits although only the first two are significant figures.

2. Wells with cells highlighted in tan have or have had chloride concentrations above 19,000 mg/L (hypersaline) and blue highlighted text indicates well has transitioned from hypersaline to saline since RWS startup.

3. Values in green are less than the historical period of record minimum result.

4. TPGW-22 sampling initiated in March 2021; TPGW-23 sampling initiated in September 2022.

5. *March 2018 baseline chloride values for TPGW-19M and TPGW-19D are potentially biased high and value for TPGW-12M is potentially biased low but data usable.

6. TPGW-18 cluster baseline data is from April 2018.

Key:

NA = not available as wells were not yet installed.

Table 3.1-2. Monitoring Well Baseline and Year 5 Quarterly (Sept 2022 to June 2023) and September 2023 Field Salinity Sample Results Baseline Additional Salinity Year 5 Salinity (PSU)

Date Quarter (PSU) 03/2018 09/2022 12/2022 03/2023 06/2023 09/2023 Wells Between CCS and L-31E Canal Near Hypersaline Source TPGW-2S 42.8 26.3 29.8 25.8 25.7 19.4 TPGW-2M 50.9 50.6 50.6 48.4 49.5 46.6 TPGW-2D 51.6 52.1 52.0 51.4 51.2 51.2 TPGW-15S 33.1 16.2 25.4 24.9 15.7 1.8 TPGW-15M 49.0 40.3 41.2 38.4 39.7 34.0 3-5

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Baseline Additional Salinity Year 5 Salinity (PSU)

Date Quarter (PSU) 03/2018 09/2022 12/2022 03/2023 06/2023 09/2023 TPGW-15D 50.8 50.1 49.8 49.6 49.5 49.7 TPGW-17S 42.6 36.8 36.4 34.8 35.4 35.7 TPGW-17M 49.9 44.6 44.2 42.4 43.2 42.0 TPGW-17D 48.0 47.4 47.1 46.7 46.6 45.5 TPGW-L3-18 3.6 2.6 0.5 0.9 0.4 0.4 TPGW-L3-58 53.0 52.2 50.5 50.0 48.6 48.3 TPGW-L5-18 2.3 0.5 0.4 0.8 0.3 0.3 TPGW-L5-58 49.6 47.9 47.0 47.4 48.3 47.1 Compliance Zone Wells TPGW-1S 32.4 8.0 16.2 16.6 14.9 4.3 TPGW-1M 48.5 42.3 41.7 41.0 38.2 36.7 TPGW-1D 48.0 47.8 47.1 47.0 47.1 46.5 TPGW-4S 4.1 3.1 3.2 4.1 3.8 1.5 TPGW-4M 25.4 26.5 25.9 26.0 25.8 25.5 TPGW-4D 26.3 27.7 26.7 26.3 26.9 26.7 TPGW-5S 0.5 0.5 0.4 0.4 0.4 0.4 TPGW-5M 21.4 16.7 16.3 15.5 14.6 13.2 TPGW-5D 23.1 23.4 23.2 23.2 23.1 23.2 TPGW-6S 0.8 0.8 0.7 0.8 0.7 0.7 TPGW-6M 13.8 14.6 14.5 14.44 14.0 14.3 TPGW-6D 14.7 15.3 15.4 15.09 15.3 14.9 TPGW-12S 30.8 34.0 31.1 30.5 32.2 30.2 TPGW-12M 39.4 35.4 35.6 35.2 34.8 35.2 TPGW-12D 44.1 45.4 44.8 44.7 44.4 44.6 TPGW-18S 22.6 3.8 3.9 4.0 3.9 2.7 TPGW-18M 40.7 39.0 38.4 38.7 38.0 37.7 TPGW-18D 42.1 39.2 38.7 39.3 38.1 38.1 TPGW-19S 3.4 1.3 1.8 1.6 1.9 1.6 TPGW-19M 39.2 32.4 33.8 31.9 31.4 31.6 TPGW-19D 40.8 40.6 41.0 40.3 40.0 39.9 TPGW-22S NA 27.7 27.3 27.1 27.0 26.5 TPGW-22M NA 37.4 36.0 36.6 36.2 35.4 TPGW-22D NA 37.6 36.8 36.4 36.5 36.5 TPGW-23S NA 14.6 20.7 20.5 21.23 19.3 3-6

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Baseline Additional Salinity Year 5 Salinity (PSU)

Date Quarter (PSU) 03/2018 09/2022 12/2022 03/2023 06/2023 09/2023 TPGW-23M NA 38.2 38.0 37.0 36.4 40.1 TPGW-23D NA 41.3 41.7 41.0 41.1 37.5 TPGW-G21-18 0.3 0.2 0.2 0.3 0.3 0.3 TPGW-G21-58 12.2 12.2 12.3 11.9 11.4 11.5 TPGW-G28-18 1.3 0.9 0.8 0.8 0.7 0.7 TPGW-G28-58 25.0 25.6 25.2 25.2 24.7 25.0 Notes:

1.Field salinity sample results are reported to two digits.

2. Wells with cells highlighted in tan have or have had chloride concentrations above 19,000 mg/L (hypersaline) and blue highlighted text indicates well has transitioned from hypersaline to saline since RWS startup.

3. Values in green are less than the historical period of record minimum result.

4. TPGW-22 sampling initiated in March 2021; TPGW-23 sampling initiated in September 2022.

Key:

NA = not available are wells were not yet installed.

Table 3.1-3. Monitoring Well Baseline and Year 5 Quarterly (Sept 2022 to June 2023)

Tritium Concentration Data Baseline Tritium Year 5 Tritium (pCi/L)

Date (pCi/L) 03/2018 9/2022 12/2022 03/2023 06/2023 Wells Between CCS and L-31E Canal Near Hypersaline Source TPGW-2S 2166 762 1327 899 800 TPGW-2M 3130 2947 3286 3101 2963 TPGW-2D 3123 2608 2632 2706 2705 TPGW-15S 1555 694 2398 3128 677 TPGW-15M 2605 4714 5142 5152 5218 TPGW-15D 2509 3168 3387 3264 3296 TPGW-17S 1482 595 543 549 511 TPGW-17M 2518 1245 1246 1183 1026 TPGW-17D 2272 1693 1715 1600 1488 TPGW-L3-18 108 61.8 14.7 52.9 113 TPGW-L3-58 3014 5091 5027 4948 4653 TPGW-L5-18 86.7 22.8 30.1 37.5 80.2 TPGW-L5-58 2640 1824 1859 1837 1839 Compliance Zone Wells TPGW-1S 954 98.0 232 218 246 3-7

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Baseline Tritium Year 5 Tritium (pCi/L)

Date (pCi/L) 03/2018 9/2022 12/2022 03/2023 06/2023 TPGW-1M 2173 1971 1885 2091 2959 TPGW-1D 2307 1904 1929 1885 1840 TPGW-4S 17.4 9.6 0.5 5.1 11.9 TPGW-4M 342 264 289 289 285 TPGW-4D 403 346 339 343 333 TPGW-5S 10.9 7.8 5.2 8.3 -6.4 TPGW-5M 271 146 137 143 232 TPGW-5D 362 297 297 318 339 TPGW-6S 5.1 5.4 -1.7 -3.3 12.0 TPGW-6M 6.3 7.4 -8.8 -4.3 11.7 TPGW-6D 8.2 15.3 -10.8 8.0 10.4 TPGW-12S 46.4 26.6 18.5 27.0 14.8 TPGW-12M 931 185 197 174 147 TPGW-12D 1344 1024 960 976 939 TPGW-18S 550 10.8 -1.8 2.3 -6.2 TPGW-18M 1568 1165 1128 1115 1075 TPGW-18D 1600 1168 1127 1184 1047 TPGW-19S 42.9 17.9 18.0 18.6 21.2 TPGW-19M 864 413 411 427 417 TPGW-19D 1082 806 816 794 697 TPGW-22S NA 355 337 306 291 TPGW-22M NA 602 659 663 574 TPGW-22D NA 768 773 589 721 TPGW-23S NA 27.3 26.9 31.6 13.4 TPGW-23M NA 736 694 665 626 TPGW-23D NA 883 832 879 872 TPGW-G21-18 8.5 10.2 1.9 7.5 -7.2 TPGW-G21-58 40.0 37.8 32.8 34.8 37.4 TPGW-G28-18 7.3 8.5 2.7 -1.6 3.4 TPGW-G28-58 333 317 283 287 266 Notes:

1. Wells with cells highlighted in tan have or have had chloride concentrations above 19,000 mg/L (hypersaline) and blue highlighted text indicates well has transitioned from hypersaline to saline.

2. Values in green are less than the historical period of record minimum result.

3. TPGW-22 sampling initiated in March 2021; TPGW-23 sampling initiated in September 2022.

Key:

NA = not available as wells were not yet installed.

3-8

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data 3.2 WATER QUALITY CONDITIONS AND TRENDS Remedial measures have resulted in reductions to saltwater concentrations in the CCS, groundwater under the CCS, and in groundwater west and north of the plant site, to differing degrees and distances. Shallow groundwater monitoring wells were the first to respond to the remediation actions with salinity reductions expanding to intermediate and deep monitoring wells as the remediation progressed. Effects of the recovery well system operations on salinity levels continue to be observed in monitoring wells as far as 3 miles west of the CCS.

Remediation efforts have resulted in the reductions in concentrations of salinity constituents in monitoring stations in the source areas (i.e., CCS and underlying groundwater) and in most groundwater monitoring sites west and north of the CCS. This section focuses on the groundwater quality and trends observed from the monitoring well data.

3.2.1 Source Area Wells Freshening actions to curtail hypersalinity in the CCS began in November 2016 with use of non-potable, slightly brackish Upper Floridan aquifer (UFA) groundwater to replace freshwater lost to evaporation during cooling. The freshening has not only lowered the annual average CCS surface water to a salinity similar to Biscayne Bay, it has also lowered the concentration of hypersaline groundwater in the source area under the CCS (FPL 2023a). Elimination of hypersaline recharge from the CCS, combined with the extraction of hypersaline groundwater by the RWS and UIC test production wells, has reduced the salt mass beneath the CCS and the driving head of the higher salinity/density water, facilitating the recovery wells retraction of the hypersaline plume west of the L-31E canal and north of the property.

Well cluster TPGW-13 is located on an interior berm within the CCS (Figure 3.1-1) and is reflective of groundwater conditions in the hypersaline source area. This well is not used to monitor the progress of RWS operations but provides insights into groundwater changes under the CCS as freshening and RWS operations progress.

Since 2010, for the first 7 or 8 years of monitoring, the chloride concentrations at all three depths were consistently 32,000 mg/L or higher with the shallow well TPGW-13S having values often above 35,000 mg/L. With the initiation of freshening and RWS operations, gradual declines in chloride and salinity have been observed in all three wells at the site since 2016. However, since November 2022, the declines have been dramatic in the shallow well TPGW-13S with historical lows measured for the last three quarters and a clear, declining trend based on the analytical data and automated salinity data (Figure 3.2-1). The lowest chloride concentration and average monthly salinity of 24,000 mg/L and 45 PSU, respectively, were recorded in September 2023 at TPGW-13S. A historical low chloride concentration and monthly average salinity were also recently recorded at TPGW-13M (29,400 mg/L in March 2023 and 52.2 PSU in September 2023).

3-9

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.2-1 shows the changes in average monthly salinity values based on automated data since March 2018, which is supported by the quarterly chloride and salinity field data. The monthly automated data better illustrates the timing of the decline at TPGW-13S than the quarterly data does. The dramatic decline first observed in the shallow well was expected as the hypersaline conditions are improving vertically with freshening of the overlying CCS surface water.

Figure 3.2-1. Declining Saltwater Values in CCS Source Well Cluster TPGW-13 3.2.2 Trends for Monitoring Wells West and North of the CCS The primary focus of discussion and analysis of trends in this section is on monitoring clusters that have one or more wells that are hypersaline or individual wells, such as TPGW-L3 and TPGW-L5, that are hypersaline. However relevant information on several other wells of interest is presented.

Groundwater in all of the wells between the CCS and L-31E canal (well clusters TPGW-2, TPGW-15, and TPGW-17, and individual wells TPGW-L3-58, and TPGW-L5-58) have been or are still hypersaline. Two of the wells, TPGW-2S and TPGW-15S, were hypersaline at the start of RWS operation, but they transitioned to saline and stayed saline within the first year or two of remediation. Of the wells in the compliance zone, six clusters (TPGW-1, TPGW-12, TPGW-18, TPGW-19, TPGW-22, and TPGW-23) have wells at two depths (intermediate and deep) that are or were hypersaline, while the shallow wells have never been hypersaline except for TPGW-1S and, intermittently, TPGW-12S. Very early in RWS operations, TPGW-1S transitioned from hypersaline to saline conditions. Well cluster TPGW-12 is located adjacent to Biscayne Bay and in an area that receives tidal inflow. Chloride concentrations at TPGW-12S have averaged 17,390 mg/L from March 2018 through September 2023, with only four values measured over 19,000 mg/L (19,100, 19,300, 19,500, and 19,800 mg/L), while tritium values (average of 41 picocuries per liter [pCi/L]) indicate little, if any, CCS influence.

3-10

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data To assess the influence of the RWS operation on the groundwater over time, Mann-Kendall trend analyses and regression analyses were conducted on quarterly chloride, salinity, and tritium data from March 2018 (baseline pre-RWS startup) to September 2023 on wells or well clusters where at least one well is still hypersaline. Mann-Kendall analyses were conducted using XLStat (Addinsoft Inc., Paris, France); the regression analyses were conducted using Statistix v. 10 (Analytical Software Inc., Tallahassee, Florida); and regression lines graphics and best fit line equations were generated by Excel.

Table 3.2-1 and Figure 3.2-2 provides a summary of Mann-Kendall results for wells that were or still are hypersaline. Nearly all the wells show a statistically significant declining trend in saltwater concentrations based on quarterly chloride and salinity sampling results and lessening CCS influence based on quarterly tritium results. Where the changes in values over time are limited, sometimes only one of the parameters for saltwater shows a trend such as at TPGW-12S, TPGW-15D, TGW-19D, TPGW-22D. As previously discussed, the trend at TPGW-12S is influenced more by Biscayne Bay than the CCS. There are several other wells that show no trend in saltwater reductions, such as TPGW-2S, TPGW-22S and TPGW-22M. At TPGW-2S, the chloride (beginning at ~25,000 mg/L) and salinity (beginning at ~43 PSU) concentrations dropped dramatically after the start of RWS operations; but during the past five years, they have fluctuated seasonally, although still below hypersaline conditions (average chloride since September 2022 is 14,100 mg/L and salinity is 25.2 PSU). At TPGW-22S and TPGW-22M, the pre-RWS groundwater salinity and chloride concentrations are unknown, so a determination cannot be made about whether there has been any decline in concentrations since startup of the RWS. TPGW-22S is not hypersaline; TPGW-22M is hypersaline; and there has not been a statistically significant trend in salinity, chloride, or tritium in either station since data collection began approximately 2.5 years ago.

Nearly all wells show a declining trend for tritium which indicates less CCS influence over time and the halting and retraction of the hypersaline plume. Some of this decline is due to the natural decay of tritium; however, a decay-based decline would not be observed if there was an ongoing source of CCS hypersaline groundwater. There are two wells, TPGW-15M and TPGW-15D, that show increasing trends in tritium. These increases are probably related to RWS pumping as this well cluster is situated between the CCS and RWS-3 (located less than 0.5-mile northwest of the CCS). It is suspected that groundwater from under the CCS which is getting lower in specific conductance and chloride due to UFA freshening but is still high in tritium may be pulled past TPGW-15, thereby increasing the percentage of CCS-sourced groundwater which is reflected in higher tritium concentrations.

Figures 3.2-3 and 3.2-4 show the results of the regression analysis with parabolic trend lines for chloride for some of the hypersaline well clusters in the area between the CCS and L-31E canal and in the compliance zone respectively. The figures for the remaining hypersaline wells, along with regression graphics for quarterly salinity and tritium data, are provided in Appendix E.

Time-series figures for weekly average automated salinity data are also in Appendix E. These figures provide insight to the amount of change that has occurred since the start of RWS operations through September 2023 and the timing of those changes. For plotting the data, both linear regression and polynomial regressions were assessed. The polynomial regressions tended 3-11

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data to show better fits of the data. Note that the resulting regression equations only show a slope of a line for the data evaluated, and care must be taken in determining trends (or lack thereof) or whether there has been an overall change in concentrations since the start of RWS operations.

Table 3.2-1. Mann-Kendall Trend Analyses for Wells that Were/Are Hypersaline SALINITY CHLORIDE TRITIUM Site 1 Mar 18 - Sept 23 Mar 18 - Sept 23 Mar 18 - June 231 1

Wells Between CCS and L-31E Canal Near Hypersaline Source TPGW-2S Decrease Decrease Decrease TPGW-2M Decrease Decrease No Trend TPGW-2D Decrease Decrease Decrease TPGW-15S No Trend No Trend No Trend TPGW-15M Decrease Decrease Increase TPGW-15D Increase No Trend Increase TPGW-17M Decrease Decrease Decrease TPGW-17D Decrease Decrease Decrease TPGW-L3-58 Decrease Decrease No Trend TPGW-L5-58 Decrease Decrease No Trend Compliance Zone Wells TPGW-1S Decrease Decrease Decrease TPGW-1M Decrease Decrease No Trend TPGW-1D Decrease Decrease Decrease TPGW-12M Decrease Decrease Decrease TPGW-12D No Trend No Trend Decrease TPGW-18M Decrease Decrease Decrease TPGW-18D Decrease Decrease Decrease TPGW-19M Decrease Decrease Decrease TPGW-19D Decrease No Trend Decrease TPGW-22M No Trend No Trend No Trend TPGW-22D Decrease No Trend Decrease TPGW-23M - - -

TPGW-23D - - -

NOTES:

- TPGW-22 came online in February 2021 so limited data for trend analysis.

- TPGW-23 came online in February 2022. Not sufficient data for trend analysis.

- Wells with cells shaded in tan indicate station have had or still have chloride values >19,000 mg/L.

- Wells highlighted in blue have transitioned from hypersaline to saline due to RWS operation and chloride concentrations have stayed below 19,000 mg/L.

- Text/Trends highlighted in green are indications of postive RWS influence.

KEY:

1 First sample collected at TPGW-18 in April 2018 and TPGW-22 in March 2021.

3-12

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.2-2. Trends in Chloride, Salinity and Tritium for Select Hypersaline Monitoring Wells 3-13

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Chloride (March 2018 - Sept 2023) 35000 TPGW-2 30000 25000 Chloride (mg/L) 20000 15000 10000 5000 0

Mar-18 Mar-19 Mar-20 Mar-21 Mar-22 Mar-23 35000 TPGW-2S TPGW-2M TPGW-2D TPGW-15 30000 25000 Chloride (mg/L) 20000 15000 10000 5000 0

Mar-18 Mar-19 Mar-20 Mar-21 Mar-22 Mar-23 35000 TPGW-15S TPGW-15M TPGW-15D TPGW-17 30000 25000 Chloride (mg/L) 20000 15000 10000 5000 0

Mar-18 Mar-19 Mar-20 Mar-21 Mar-22 Mar-23 Shallow Medium Deep Figure 3.2-3. Regression Analyses Trends for Select Hypersaline Wells Between CCS and L-31E 3-14

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Chloride (March 2018 - Sept 2023) 35000 TPGW-1 30000 25000 Chloride (mg/L) 20000 15000 10000 5000 0

Mar-18 Mar-19 Mar-20 Mar-21 Mar-22 Mar-23 35000 TPGW-1S TPGW-1M TPGW-1D TPGW-18 30000 25000 Chloride (mg/L) 20000 15000 10000 5000 0

Mar-18 Mar-19 Mar-20 Mar-21 Mar-22 Mar-23 TPGW-18S TPGW-18M TPGW-18D 35000 TPGW-19 30000 25000 Chloride (mg/L) 20000 15000 10000 5000 0

Mar-18 Mar-19 Mar-20 Mar-21 Mar-22 Mar-23 Shallow Medium Deep Figure 3.2-4. Regression Analyses Trends for Select Wells in Compliance Zone 3-15

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figures 3.2-5 and 3.2-6 compare the March 2018 baseline chloride and tritium concentration to the average annual concentrations (based on four quarters each period) for each of the past five years, and the September 2023 data by depth interval for all hypersaline monitoring wells. Due the short period of record and baseline data not being available, TPGW-22 and TPGW-23 are not included in Figures 3.2-5 and 3.2-6.

The shallow zone hypersaline wells west of the CCS (source area wells TPGW-2S and TPGW-15S, and TPGW-17S; and compliance zone well TPGW-1S) have shown significant amounts of salt mass decline since the start of remediation (Figure 3.2-5). The decline in most of the shallow wells occurred within the first several years of RWS operations, and the amount of reduction is leveling off as the stations approach a new sustainable seasonal salinity range. Of these four shallow hypersaline wells, three of the wells (TPGW-1S, TPGW-2S, and TPGW-15S) have transitioned from hypersaline to saline within two years of RWS operation and the trends are still either declining or stable. The other well (TPGW-17S) is still hypersaline; while average annual chloride concentrations declined from almost 25,000 mg/L to nearly 20,000 mg/L after the first year of RWS operation. Chloride concentrations have remained around 20,000 mg/L since then. Monitoring well TPGW-17S is approximately 0.5 mile west of the CCS and over 0.25 mile further west than TPGW-1S and TPGW-2S. However, this well is also adjacent to the S-20 discharge canal, which is tidally inundated with seawater that floods low lying wetlands during the dry season, resulting in hypersaline recharge to the aquifer at the monitoring well site.

If the source of evaporative hypersaline recharge to the aquifer persists at this location, the average annual chloride levels for this well may continue as reflected in the past four years as hovering around 20,000 mg/L.

As remediation has progressed, responses in the intermediate hypersaline wells are becoming more evident, with gradually consistent declines in chloride concentrations as exhibited at TPGW-15M and compliance zone wells TPGW-1M, TPGW-17M, TPGW-18M and TPGW-19M (Figure 3.2-5). In September 2023, monitoring well TPGW-15M had a chloride concentration of 19,500 mg/L; the baseline concentration in March 2018 was 30,000 mg/L.

While this is only one quarter where the chloride concentrations at TPGW-15M have dropped below 20,000 mg/L and are approaching 19,000 mg/L, this well may be transitioning from hypersaline to saline conditions. Monitoring well TPGW-19M had two quarters (December 2022 and September 2023) of chloride concentration slightly below 19,000 mg/L, with an average value over the past five quarters of 19,040 mg/L or, based on validity of the data to two significant figures, is 19,000 mg/L. The average of the last five quarterly salinity value is 32.2 PSU, which also confirms the water is not hypersaline at TPGW-19M.

The deep wells show less consistent change than the intermediate depth wells (Figure 3.2-5) as it may be too soon for larger scale salinity reduction along the base of the aquifer after five years of remediation efforts. Nonetheless, most of the deep wells show a declining trend. The deep well closest to the western edge of the hypersaline plume (TPGW-18D) is showing the greatest and most consistent reduction in saltwater content (4,900 chloride mg/L or nearly 19% decline),

compared to the rest of the deep wells, as the plume retracts eastward.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data 35000 Average Chloride Conc. (mg/L) 30000 25000 20000 15000 10000 5000 0

TPGW-1S TPGW-2S TPGW-12S TPGW-15S TPGW-17S TPGW-18S TPGW-19S Mar-18 9/18-6/19 9/19-6/20 9/20-6/21 9/21-6/22 9/22-6/23 Sep-23 35000 30000 Average Chloride Conc. (mg/L) 25000 20000 15000 10000 5000 0

TPGW-1M TPGW-2M TPGW-12M TPGW-15M TPGW-17M TPGW-18M TPGW-19M TPGW-L3-58 TPGW-L5-58 Mar-18 9/18-6/19 9/19-6/20 9/20-6/21 9/21-6/22 9/22-6/23 Sep-23 35000 Average Chloride Conc. (mg/L) 30000 25000 20000 15000 10000 5000 0

TPGW-1D TPGW-2D TPGW-12D TPGW-15D TPGW-17D TPGW-18D TPGW-19D Mar-18 9/18-6/19 9/19-6/20 9/20-6/21 9/21-6/22 9/22-6/23 Sep-23 Figure 3.2-5. Summarized Changes in the Shallow, Intermediate, and Deep Well Chloride Concentrations 3-17

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data 5500 5000 Average Tritium Conc. (PCi/L) 4500 4000 3500 3000 2500 2000 1500 1000 500 0

TPGW-1S TPGW-2S TPGW-12S TPGW-15S TPGW-17S TPGW-18S TPGW-19S Mar-18 9/18-6/19 9/19-6/20 9/20-6/21 9/21-6/22 9/22-6/23 5500 5000 Average Tritium Conc. (pCi/L) 4500 4000 3500 3000 2500 2000 1500 1000 500 0

TPGW-1M TPGW-2M TPGW-12M TPGW-15M TPGW-17M TPGW-18M TPGW-19M TPGW-L3-58 TPGW-L5-58 Mar-18 9/18-6/19 9/19-6/20 9/20-6/21 9/21-6/22 9/22-6/23 5500 5000 Average Tritium Conc. (pCi/L) 4500 4000 3500 3000 2500 2000 1500 1000 500 0

TPGW-1D TPGW-2D TPGW-12D TPGW-15D TPGW-17D TPGW-18D TPGW-19D Mar-18 9/18-6/19 9/19-6/20 9/20-6/21 9/21-6/22 9/22-6/23 Figure 3.2-6. Summarized Changes in the Shallow, Intermediate, and Deep Well Tritium Concentrations 3-18

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Changes in tritium concentrations follow a similar pattern as chloride and salinity with depth and location (Figure 3.2-6); however, the decline in tritium is occurring faster in some wells than the decline in chloride and salinity. These may be due to the combined factors of half-life decay of tritium (12.33 years) combined with physical reduction of tritiated water by the RWS.

The monitoring wells provide directly measured water quality values that are critical to assessing the progress toward remediation of the plume west and north of the CCS. However, given the size of the area being monitored, volume of the hypersaline plume, distance between the wells, narrow zone of measurement (2- to 5-ft length of the Biscayne aquifer over a radial distance of a foot or two), and lithologic variability in the Biscayne aquifer, it is not possible to produce comprehensive conclusions regarding the progress of remediation on these data alone. Other tools, such as AEM and modeling, are needed to complement the monitoring well data and generate an understanding of what is occurring in the area between wells. The lack of large declines in hypersaline chloride concentrations in certain monitoring wells should not be construed to mean the plume is not being reduced in volume or extent, rather that the edge of the hypersaline plume has yet to reach the particular monitoring interval at that well location. The CSEM survey results that are presented in Section 4 and modeling results in Section 5 supplement the monitoring well results.

Figure 3.2-7 shows the chloride concentration in March 2018 for currently hypersaline wells prior to the start of RWS operations (top of the orange color of the bar), with the exception of TPGW-18, TPGW-22, and TPGW-23. The chloride concentration of these three wells are based on when they were installed and when data was initially collected: TPGW-18 in April 2018, TPGW-22 in March 2021, and TPGW-23 in September 2022.

There are two wells in March 2018 that appeared to have biased high chloride levels (TPGW-19M and TPGW-19D) and one well with biased low chloride concentrations (TPGW-12M) based on prior and subsequent near-term data. For these three wells, June 2018 chloride values were used in the graph. The June 2018 data for these three wells did not appear to be affected by RWS operations, so use of the June 2018 data is a reasonable surrogate for the March 2018 baseline data. Chloride concentrations in September 2023 (top of blue bar) are also shown. The orange portion of the bar shows how much the chloride concentration has dropped from 2018, or when data collection began, to September 2023. The blue portion of the bar shows how much more the concentration would need to drop from the average chloride concentration over the past four quarters (December 2022-September 2023) to reach the 19,000 mg/L target.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.2-7. Progress of Chloride Reduction in Currently Hypersaline Wells Chloride reductions in the compliance area in the middle well at TPGW-5 and TPGW-G21 (58), which are over 3 miles west of the RWS, is an indication of the lateral reach of the withdrawal system.

Spatially, the greatest reductions in saltwater concentrations in the monitoring wells have generally occurred in the area west of the northern portion of the CCS, such as in well clusters TPGW-1, TPGW-15, TPGW-18, and TPGW-19 depending upon depth; however, lesser reductions are occurring throughout much of the area being monitored. A review of changes in chloride concentrations and salinity in wells further west of the CCS (near the western edge of the compliance boundary) indicate positive influence of RWS operations. Figure 3.2-8 shows chloride concentrations at intermediate depth wells TPGW-5M and TPGW-G21 (58) which are over 3 miles west of the northern portion of the CCS and exhibit declining values over the past 2.5 years.

The entire period of record, beginning in 2010, is included to show how the values changed, particularly at TPGW-G21 (58), and to point out a limitation of the Mann-Kendall or regression analysis if used in isolation. Mann-Kendall analyses of chloride and salinity at TPGW-5M for the period from March 2018 through September 2023 indicate a declining trend, while a similar analysis for TPGW-G21 (58) indicates no trend. Figure 3.2-8 shows there is a declining chloride trend in both wells since at least March 2021, but the recent trend at TPGW-G21 (58) is affected by the prior three years of an increasing trend. No declining trends were noted at wells TPGW-4M and TPGW-G28 (58), which are located due south of TPGW-G21 and west of the south half of the CCS, indicating more progress to date is in the area west of the northern half of the CCS.

3-20

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.2-8. Declining Trend in Chloride Concentration in TPGW-5M and TPGW-G21 (58) since March 2021.

3.3 CHLORIDE CONCENTRATION CONTOUR MAPS Comparison of the 2018 and 2023 maps show the 19,000 mg/L contour line is being retracted closer to the CCS for all three depth horizons, which is supported by other data findings reported in this Year 5 RAASR.

As requested by MDC, plan view chloride concentration contour maps were created for the shallow, middle, and deep monitoring horizons using chloride measurements from up to 23 monitoring well sites and ten CSEM chloride measurement sites for comparison of the estimated location of the 2023 versus 2018 baseline orientations of the 19,000 mg/L chloride isochlor contour lines. The contours were objectively generated by Earth Volumetric Studio, a program developed by C Tech Development Corporation, using kriging algorithms. Isochlors were generated using the kriging software and contoured for chloride levels of 1,000, 4,000, 9,000, 14,000, 19,000, and 24,000 mg/L. These figures were modified to clip or blank isochlors that trend into areas not supported by monitoring data or outside of the remediation compliance area east and south of the CCS.

To reduce some of the uncertainty in spatial data gaps between monitoring wells in the area between the CCS and Tallahassee Road, which covers the western extent of the hypersaline plume and CSEM survey data, chloride estimates from the CSEM survey were added for mapping purposes at nine different areas at shallow, middle, and deep layers. The CSEM chloride values were added at midpoints between monitoring wells to place the CSEM points in locations that were least represented by monitoring well data. Data from CSEM layers 11 and 13 were used to represent the middle and deep zones, respectively. The added CSEM locations and their spatial relationships to the monitoring wells are shown graphically in Figures 3.3-1 through 3-21

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data 3.3-6. Chloride concentrations for the 2018 and 2023 TPGW and CSEM monitoring points used in these figures are provided in Tables 3.3-1 and 3.3-2 respectively.

The 2023 chloride contour maps for the shallow, middle, and deep layers are shown on Figures 3.3-1 through 3.3-3. Figures 3.3-4 through 3.3-6 show comparative positions of the 19,000 mg/L chloride contour for the 2018 baseline conditions and the 2023 Year 5 conditions. Comparison of the 2018 and 2023 maps show the 19,000 mg/L contour line is retracting closer to the CCS for all three depth horizons, which is supported by other data findings reported in this Year 5 RAASR. Any definitive conclusions in specific areas, however, are constrained in accuracy by the spatial distances between the existing monitoring wells, the degree that chloride concentrations change spatially, differing vertical depths or relative depths of monitoring well screens, differences between the CSEM and laboratory determination of chloride concentration, the size of the study area, and the assumptions of hydraulic continuity among all monitoring wells in each layer.

3-22

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Table 3.3-1. Chloride concentrations for the 2018 TPGW and CSEM monitoring sites.

June 2018 Chloride Contour Values Shallow Elevation Middle Elevation Deep Elevation State Plane X State Plane Y Site ID Chlorides (mg/L) Chlorides (mg/L) Chlorides (mg/L) Coordinate Coordinate TPGW-1 17300 28300 28400 869225.3 400730.5 TPGW-2 24300 30400 31500 864219.2 381474 TPGW-3 23300 26500 27600 871575.3 368172.9 TPGW-4 1810 14700 15800 850233.5 377150 TPGW-5 146 12500 13600 852972.1 396535.9 TPGW-6 224 8210 8530 858446.4 408312.1 TPGW-7 36 41 3400 844942.5 400397.6 TPGW-8 29 28 39 836910.9 391671.4 TPGW-9 24 24 24 828415.8 378735.3 TPGW-10 21100 21300 28600 879004.4 403070.5 TPGW-11 21300 22900 26800 885870.8 387154.5 TPGW-12 13200 24600 25900 874049.6 405872.6 TPGW-13 33100 33100 33900 870094.3 386025.2 TPGW-14 22200 23300 29300 878659 371580.1 TPGW-15 16200 29300 27900 870450.8 399957.9 TPGW-16 24600 30800 31400 876836.8 383976.9 TPGW-17 25100 29200 29900 862330.2 376136.6 TPGW-18 12100 24100 24100 863570.2 395419.3 TPGW-19 4190 23100 23900 867748.9 405715.4 TPGW-20 37 32 31 843026 406557.8 TPGW-21 NA NA 50 842278.1 396123.8 TPGW-22 NA NA NA 854286.4 376117.6 TPGW-23 NA NA NA 871250.1 408416.8 CSEM1 1293 22083 17282 863835.9 404521.3 CSEM2 195 2747 8927 855709.3 402424 CSEM3 1874 8671 9267 860360.5 401125.6 CSEM4 4316 19362 15769 861098.7 398633.2 CSEM5 35324 31156 26473 861533.2 391280.5 CSEM6 5583 33576 18585 858595.7 389004.9 CSEM7 1418 25068 10259 851602.8 386842.9 CSEM8 19578 40283 14357 857226.3 379312 CSEM9 31288 37118 35285 860904.4 372661.4 CSEM10 26420 34023 14424 857226.3 372661.4 3-23

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Table 3.3-2. Chloride concentrations for the 2023 TPGW and CSEM monitoring sites.

Sept 2023 Chloride Contour Values Shallow Elevation Middle Elevation Deep Elevation State Plane X State Plane Y Site ID Chlorides (mg/L) Chlorides (mg/L) Chlorides (mg/L) Coordinate Coordinate TPGW-1 2310 20900 26500 869225.3 400730.5 TPGW-2 11300 26500 29000 864219.2 381474 TPGW-3 22500 25400 25700 871575.3 368172.9 TPGW-4 717 14600 15600 850233.5 377150 TPGW-5 138 7160 12900 852972.1 396535.9 TPGW-6 292 8350 8620 858446.4 408312.1 TPGW-7 32 43 4660 844942.5 400397.6 TPGW-8 30 29 34 836910.9 391671.4 TPGW-9 20 24 26 828415.8 378735.3 TPGW-10 20100 21000 27600 879004.4 403070.5 TPGW-11 20600 21600 26600 885870.8 387154.5 TPGW-12 18100 20100 25500 874049.6 405872.6 TPGW-13 24200 30400 31200 870094.3 386025.2 TPGW-14 21900 22400 26400 878659 371580.1 TPGW-15 858 19500 28300 870450.8 399957.9 TPGW-16 22700 29600 29500 876836.8 383976.9 TPGW-17 20700 24700 26500 862330.2 376136.6 TPGW-18 1410 21400 21500 863570.2 395419.3 TPGW-19 781 18800 23200 867748.9 405715.4 TPGW-20 NA NA 3040 843026 406557.8 TPGW-21 27 29 494 842278.1 396123.8 TPGW-22 15600 20600 21000 854286.4 376117.6 TPGW-23 10500 22200 23300 871250.1 408416.8 CSEM1 1100 23196 10797 863835.9 404521.3 CSEM2 196 5371 13951 855709.3 402424 CSEM3 892 10736 7719 860360.5 401125.6 CSEM4 1655 15695 12097 861098.7 398633.2 CSEM5 17182 21894 24510 861533.2 391280.5 CSEM6 3369 21511 14847 858595.7 389004.9 CSEM7 1007 20950 6633 851602.8 386842.9 CSEM8 9481 32738 13534 857226.3 379312 CSEM9 19241 42633 31497 860904.4 372661.4 CSEM10 21303 26537 11325 857226.3 372661.4 3-24

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.3-1. Groundwater Chloride Contour Map based on 2023 Shallow Monitoring Well Data and CSEM Horizon Chloride Values 3-25

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.3-2. Groundwater Chloride Contour Map based on 2023 Middle Monitoring Well Data and CSEM Horizon Chloride Values 3-26

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.3-3. Groundwater Chloride Contour Map based on 2023 Deep Monitoring Well Data and CSEM Horizon Chloride Values 3-27

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.3-4. Comparison of the 2018 Baseline and 2023 Year 5 Inland Extent of Hypersaline Groundwater (19,000 mg/L Chloride Isochlor) based on Shallow Horizon Monitoring Well Data 3-28

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.3-5. Comparison of the 2018 Baseline and 2023 Year 5 Inland Extent of Hypersaline Groundwater (19,000 mg/L Chloride Isochlor) based on Middle Horizon Monitoring Well Data 3-29

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.3-6. Comparison of the 2018 Baseline and 2023 Year 5 Inland Extent of Hypersaline Groundwater (19,000 mg/L Chloride Isochlor) based on Deep Horizon Monitoring Well Data 3-30

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data 3.4 GROUNDWATER LEVEL TRENDS Groundwater levels in the area vary seasonally, with levels generally higher during the wet season and lower during the dry season. However, groundwater levels can also vary daily, rise within hours of a rainfall event, and in some wells change hourly with tides. Despite these complicating factors, groundwater contouring can provide broad insights into regional gradients, flow directions, and flow rates. Figures 3.4-1 and 3.4-2 show groundwater elevation contour maps generated from daily average automated water level data for two separate days: April 1, 2023, representing dry season conditions and September 24, 2022, representing wet season conditions. These data were collected from shallow monitoring wells TPGW-1S, TPGW-2S, TPGW-4S, TPGW-5S, TPGW-6S, TPGW-7S, TPGW-12S, TPGW-15S, TPGW-17S, TPGW-18S, TPGW-19S and TPGW-22S. The contours were developed using manual linear interpolation contouring methods and best professional judgment and informed by the above-referenced monitoring wells plus wells TPW-8, TPGW-9, TPGW-10, TPGW-13, TPGW-16, and TPGW-21, which are part of other monitoring efforts but not shown.

The representative groundwater contour maps for the dry (Figure 3.4-1) and wet (Figure 3.4-2) seasons indicate a generally eastward flow direction, with lower gradients from west to east this year compared to the same maps the prior year, due in part to above average rainfall. These maps are based on measured water levels and are not adjusted for freshwater head equivalents, so care must be taken to interpret the results. Because of the variable fluid densities in the Biscayne aquifer, modeling tools are needed to more accurately represent groundwater flow rates, direction, and gradients.

Regionally, the groundwater levels on September 24, 2022, (the wet season) were approximately 0.75 ft higher than April 1, 2022 (the dry season). Continuous eastward groundwater gradients with stages equal or above sea level are generally considered helpful in reducing saltwater intrusion and aid in plume remediation.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.4-1. Dry Season Water Level Contour Map (April 1, 2023) 3-32

FPL Turkey Point RAASR Year 5 N ovem ber 2023 3. Groundw ater M onitoring Data Figure 3.4-2. Wet Season Water Level Contour Map (September 24, 2022) 3-33

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4 CONTINUOUS SURFACE ELECTROMAGNETIC MAPPING SURVEY

SUMMARY

Revisions to the statistical approach used to estimate chloride concentrations from AEM bulk resistivity have been implemented to address apparent year to year measurement processing drift and the intrinsic variation in both AEM resistivity and lab chloride data. The results are more mathematically robust and are shown to reduce uncertainty in plume estimates (compared to analyses in previous years), while improving the statistical confidence of the results. These revised methods have been applied to the 2018 baseline and every subsequent survey through 2023 and presented here. Despite these improvements, significant unresolved uncertainty remains which will be the focus of further evaluation in subsequent surveys.

4.1 INTRODUCTION

Pursuant to the FDEP CO requirements of paragraph 29.a., MDC CA paragraph 17.d.iii, and as requested in item 3.b. in a letter provided to FPL by MDC dated May 15, 2017, FPL conducted the 2018 baseline CSEM survey from March 31 to April 6, 2018, using AEM methods (described in ENERCON 2016). As AEM is the methodology employed for the CSEM surveys, the acronym will be used when referring to the survey processes, procedures, and data. The purpose of the 2018 baseline survey was to map the hypersaline plume west and north of the FPL property adjacent to Turkey Point prior to the initiation of RWS operations.

Paragraph 17(d)(iii) of the MDC CA and paragraph 29(b) of the FDEP CO required that an AEM survey be conducted 30 days after the first year of RWS operation, which was initiated on May 15, 2018. The first year AEM survey was conducted from May 24 through 26, 2019, and the results were presented in the November 15, 2019, Remedial Action Annual Status Report (RAASR). Due to restrictions on international travel and health risks associated with the COVID-19 pandemic, collection of the Year 2 survey data was delayed from the originally scheduled May 2020 timeframe until September 26-27, 2020. The Year 3 and Year 4 surveys were conducted June 18-22, 2021and May 19-20, 2022, respectively. Data acquisition for the Year 5 survey (the subject of this report) occurred May 17-19, 2023.

In 2023, FPL has produced bias adjusted chloride concentration estimates from AEM bulk resistivity data using revised statistical methods that better account for intrinsic variation in both AEM resistivity and lab chloride data and apparent year to year measurement processing drift not previously considered in prior AEM survey evaluations. These methods are the result of technical discussions with MDC and are shown to reduce uncertainty in plume estimates (compared to analyses in previous years), while improving the statistical confidence of the 4-1

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary results. The revised methods have been applied to the bulk resistivity data collected during the 2018 baseline survey and the five subsequent annual RWS influenced surveys to produce consistent comparative assessment of the AEM surveys through Year 5 of remediation.

Information on data collection, data analysis, error assessment, three-dimensional (3D) mapping of the distribution of hypersaline chloride concentrations within the Biscayne aquifer and comparisons of the 2023 results with those of the 2018 baseline AEM survey are provided in the following sections and detailed in the Report on Advanced Processing and Inversion of 2023 AEM Survey Data and Estimated Chloride Concentrations near the Turkey Point Power Plant, Southern Florida produced by Aqua Geo Frameworks, LLC (AGF) (Appendix F), and the reports entitled, Turkey Point Year 5 Chloride Modeling and Estimation, and Permutation Testing and Bootstrap Estimation of the Hypersaline Plume at Turkey Point, Year 5 produced by MacStat Consulting, Ltd (Appendix G and H).

4.2 BACKGROUND

The use of AEM survey techniques to evaluate variations in bulk resistivity, and hence, water salinity, in the Biscayne aquifer, was proposed to FDEP and MDC by FPL in 2016 as an environmentally compatible method for collecting groundwater quality trend information over a large wetland compliance area (22 square miles). For water-saturated materials, bulk resistivity, or its inverse, bulk conductivity, is principally determined by pore fluid conductivity and porosity. When pore water chloride ion content is high, bulk conductivity and fluid conductivity have a nearly 1:1 relationship. This allows the measurement of fluid conductivity from bulk resistivity or conductivity values obtained from geophysical surveys. Consequently, the high electrical conductivity of saline groundwater makes it an excellent target for electrical geophysical methods. Due to lithologic effects, the relationship between bulk electrical properties and fluid conductivity must be calibrated with local water quality data. ENERCON established this relationship for the Biscayne aquifer near the CCS during performance of the proof-of-concept 2016 AEM survey as reported in PTN Cooling Canal System, Electromagnetic Conductance Geophysical Survey, Draft Final Report, Florida Power and Light Turkey Point Power Plant (ENERCON 2016).

From Year 1 through year 4, a two-equation linear regression approach similar to a USGS method (Prinos et al. 2014) was used to correlate field-measured water resistivity to AEM resistivity and to correlate laboratory chloride concentrations to field-measured resistivity. The two regression equations were combined to develop a year specific formula used to convert AEM resistivity to chloride concentration, and a year specific AEM resistivity threshold value was established that corresponded to a chloride compliance concentration of 19,000 milligrams per liter (mg/l). The calculated chloride concentrations were interpolated into a three-dimensional, multi-layer grid, and hypersaline plume volumes based on the 19,000 mg/l threshold value were calculated. Using these methods, the 2022 RAASR (Year 4) concluded that the volume of the hypersaline plume decreased by 67 percent when compared to the 2018 baseline and westward migration of the hypersaline plume has stopped.

4-2

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary MDC provided an independent peer review of the Year 1 (2019), Year 3 (2021), and Year 4 (2022) RAASR methods, findings, and conclusions. FPL worked with Miami-Dade consultants, exchanging technical information and evaluation to identify and understand limitations of the data acquisition and the methods used to convert bulk resistivity to chloride. Factors identified that influenced the results included:

differences in resistivity that were on the order of tenths of an ohm-meter the scale upon which chloride changes across the 19,000 mg/L threshold are lower than the calibration limit of the equipment (plus or minus 1 ohm-meter);

annual calibrations, signal processing software, and equipment hardware introduce variability capable of impacting volumetric plume estimations;

standard linear regressions are asymmetric and assume that the independent variable is exact and without error/uncertainty; accordingly, which variable is assigned as the dependent vs. the independent variable can significantly change the volumetric results;

the linear regression approach produced a unidirectional drift (i.e., statistical bias) contrary to the assumption of independent, random variation in the data, which should have shown random increases as well as decreases in plume volume estimates;

the method used did not address variability in porosity to any degree, leading to a significant impact on bulk resistivity of groundwater and hence, salinity and plume volume estimates.

It was agreed that both AEM bulk resistivity and lab chloride measurements, with methodological uncertainties, collected from monitoring wells open to short intervals not aligned with measured AEM earth layers, exhibit errors and random variation, and neither are exact.

Accordingly, FPL considered alternative methods to the two-equation USGS linear regression method used from Years 1 through 4 and discussed and demonstrated an alternative correlation approach with MDCs consultants. The alternative approach (the Deming regression discussed below) was successful in removing some of the variability while exposing the impact on plume volume estimates due to unaddressed variation in porosity.

For this, FPL applied a long-standing porosity correction approach used in the petroleum industry for oil reservoir porosity determination using EM geophysical logging data known as Archies Law. FPL believes that the modified data modeling and processing strategy used to develop the chloride and hypersaline plume volume estimates in this report better accounts for underlying variability by directly correlating measured chloride concentrations in monitoring wells to AEM resistivity and normalizing data to reduce year to year bias or drift. The modified data modeling and processing procedures are summarized in greater detail in Section 4.3.3 below and Appendix F and G of this report.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4.3 APPROACH AND METHODS To collect transient AEM data, an electrical current is sent through a large loop of wire consisting of multiple turns which generates an electromagnetic (EM) field. The EM field switches off and on at rapid rates. When the EM field is generated, it passes into the ground where it dissipates and decays with time, traveling deeper and spreading wider into the subsurface. The rate of dissipation is dependent on the electrical properties of the subsurface and is controlled by the material composition of the geology, including the amount of mineralogical clay, the water content, the presence of dissolved solids, and the percentage of void space. At the moment the EM field is turned off, a secondary EM field, which also begins to decay, is generated within the subsurface. The decaying secondary EM field generates a current in a receiver coil. This current is measured at several different moments in time, each moment being within a time band called a time gate. From the induced current, the time rate of decay of the magnetic field, B, is determined (dB/dt). When compiled in time, these measurements constitute a sounding at that location. Short time measurements present data on near-surface conditions while longer timed measurements collect data from greater depths below land surface. Thus, data on the decay of the magnetic field over multiple progressively longer time bands break up each sounding into sequential depth layers. By maintaining a consistent elevation of the transmitter/receiver (minor flight elevation variations are adjusted during post-processing), and using consistent time gates, the thickness of each individual earth layer derived from the field data is constant across the surveyed area relative to the land surface, with layer thickness being thinnest near the surface while deeper layers average data over progressively greater thicknesses.

Additional details of data acquisition and processing are contained in Appendix F.

The AEM survey area encompasses approximately 30 square miles of mostly wetlands located to the west and north of the CCS and includes the entirety of the 22 square mile compliance area.

Figure 4.3-1 presents Turkey Point, the CCS, the survey area and compliance boundary, monitoring well sites used to correlate chloride concentrations, and 2023 AEM survey flight lines.

The 2023 AEM survey was performed using the same airborne platform and EM technique used for the 2018 through 2022 surveys: a helicopter-borne transient EM (TEM) system developed and implemented by SkyTEM Canada, Inc. (SkyTEM) that provided nearly continuous (i.e., one sounding every 6 feet along each flight line) EM survey data within the coverage area. The geophysical data are collected using TEM sounding equipment suspended from an airborne platform flown along prescribed flight lines (transects) over the target area. In this application, the individual transects primarily run from west to east with north to south tie lines (as shown in Figure 4.3-1) and cover the entire region of interest.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.3-1. 2023 AEM Survey Area, Flight Lines, Monitoring Well Locations and Designation of Compliance Area Boundary (Orange Line) 4-5

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4.3.1 Data Acquisition and Field Processing Airborne EM data acquisition was conducted by SkyTEM during May 17-19, 2023. As changes in hypersaline extent over time are based on comparisons between baseline and current EM survey responses, multiple steps are taken prior to, during, and immediately after AEM field acquisition flights to help ensure consistent data acquisition and processing from year to year.

Steps to provide consistency in the data include the following:

Use of consistent hardware. The EM304 hardware and software has been consistently used since 2016. Since AEM systems go through constant updates and replacements that may complicate direct comparisons, SkyTEM has dedicated the EM304 unit used in our studies for use over the entire 10-year project. All software updates are provided to AGF who evaluate impacts to consistency of annual surveys. Adjustments to data processing are made and documented if software changes would otherwise result in inconsistency between survey years.

Implement consistent flight plans. Prior to flights, the detailed flight plan is reviewed with the pilot. The flight plan details flight line locations, ground speed, elevations, flight direction, ground hazards such as powerline locations, and any areas of potential EM interference. Attention and care are given to attempt to fly as close as practical the same flight path as 2018. Constant details of flight conditions, global positioning system (GPS) locations, altimeter, tilt, fight speed, etc. are recorded and reviewed after each flight. If any flight lines are found to fall out of consistency specifications, the out-of-spec flight lines are re-flown.

Equipment calibration. Prior to deployment of the EM304 system hardware to the site, it is calibrated to a ground test site in Lyngby, Denmark. After delivery to the Turkey Point site, the calibration is verified through a series of test flights that include measurement of the transmitter waveforms, verification that the receiver is properly located in a null position, and verification that all positioning instruments were functioning properly. A high-altitude test, used to verify system performance, is also conducted prior to the beginning of the surveys production flights.

In-field preliminary data verification and review. Raw flight data are transmitted upon landing to AGF for verification and quality control. If flight data were found to fall outside quality specifications, the flight segment would be re-flown and verified before proceeding to the next flight segment. This field-based quality control protocol helps ensure that the field data are complete and verified prior to completing the airborne data acquisition phase of the survey. In addition, a review of acquired raw data by SkyTEM in Denmark for primary field compensation (PFC) is conducted prior to continued data processing by AGF (Schamper et al. 2014). The primary field of the transmitter affects the recorded early time gates, which in the case of the Low Moment measurements (LM), are helpful in resolving the near-surface resistivity structure of the ground. The LM uses a sawtooth waveform which is calculated and used in the PFC correction to correct the early time gates.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Multi-zoned groundwater monitoring wells (Figure 4.3-1) were sampled during June 2023, and samples were analyzed for dissolved chloride using procedures and methods described in the approved Turkey Point QAPP (FPL 2013). The water quality data were used in the calibration and conversion of the AEM data to chloride concentrations. In addition, continuous borehole induction logging was conducted by USGS from the deepest monitoring well at each monitoring well site during March 2023 and were used as an independent comparison and verification of the airborne resistivity data.

Following data acquisition by SkyTEM, the field data were delivered directly to AGF for post-processing. The AGF-ENERCON team conducted the data processing, interpretations, method calibration, data correlations with monitoring well induction logs and water quality, and prepared the survey reports. At each sounding along a flight line, the theoretical field response of a layered earth model was calculated and compared to the actual field data and adjacent data points. The resistivities of the model layers were adjusted until the differences between the calculated (model) response and the observed field response were minimized. This spatial averaging produced laterally-constrained inversions (LCIs) and spatially-constrained inversions (SCIs) of the data collected. AGF produced LCIs and SCIs of collected data with the SkyTEM system during daily flight operations to verify and confirm the functionality of the SkyTEM system and eliminate drift or calibration concerns. These inversions were conducted using the Aarhus University Geophysics Workbench software that allowed for editing of the AEM data to remove EM couplings (i.e., noise) from power lines and pipelines. AGF also provided integration of continuous borehole induction log data as a qualitative check against field resistivity data. The inversions were then combined into an electrical resistivity model of the area which generates calibrated resistivity estimates for the survey area along each flight line.

Table 4.3-1 lists the thicknesses of the layers within the AEM model, including the upper 14 layers that account for the estimated thickness of the Biscayne aquifer in the area based on USGS maps (Fish and Stewart 1991). Layer thicknesses increase with depth as AEM resolution decreases. Layer 1 has a thickness of about 3 ft, while layer 14, with a bottom depth of approximately 100 ft, has a thickness of about 13 ft. The data in this AEM survey were inverted at each sounding, converted into two-dimensional (2D) resistivity plan view sections versus depth and displayed as resistivity profiles by layer. The plan and profile views of the AEM resistivity model for the 2023 survey are presented in Appendix F.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Table 4.3-1. Thickness and Depth to Bottom for Each Layer in the AEM Model 4.3.2 Quality Control of the AEM Data Inversion 4.3.2.1 Magnetic Field Noise and Potential Sources of Error As explained in Section 4.3.1, multiple steps are taken prior to, during, and immediately after AEM field acquisition flights to help ensure consistent data acquisition and processing from year to year; however, AEM instrumentation and data processing algorithms require annual re-calibration and adjustment that can result in year-to-year bias or drift.

Another potential source of error is the spatial displacement of the water quality samples taken from discrete intervals in the monitoring wells and the location of the nearest AEM data on a flight line. None of the monitoring wells available for calibration of the AEM data are on a flight line: all well screens are shorter than the thickness of AEM layers, and some well screens are divided by two AEM layers (see Figure 4.3-2). In addition, the AEM data average the instruments response to variations in chloride content over distances of a few tens of meters to over 100 m, while well samples come from small-diameter well screens about 1 m in length. It can be reasonably assumed that changes in pore water chloride content are smooth and not abrupt over distances of tens of meters, and the effects of spatial errors are included in the overall assessment of AEM-estimated chloride values. Porosity, groundwater content, and chloride concentration are inherently dynamic at each location, depth, and time, and measured AEM resistivity should not be considered as a fixed quantity but more of a snapshot of the electrical properties of the formation at that time.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.3-2. Monitor Well Screened Zone versus AEM Layer To improve data quality and reliability, raw field data acquired along flight lines are filtered and processed. The data are converted to a uniform transmitter coil height above the ground using the helicopter altimeter data, and a GPS location is determined for each data point. An analysis is made of background EM interference (noise) that originates from sources such as thunderstorms, large electrical motors, and power lines. Data points that are too noisy (i.e.,

where the signal is obscured by excessive background interference to a degree the data are unreliable) are blanked and not included in the data inversion. The data are examined for spikes that occur over pipelines and other conductive objects. The spikes are also blanked.

Figure 4.3-3 shows the locations of the decoupled and removed data (red lines) along the AEM flight lines and the data used in the inversion (blue lines) in the 2023 project area. A noisy area near the RWS appeared during the 2019 survey. The noise was presumed to be associated with power delivery and operation of the RWS electric pump motors. As recommended in the 2019 report, the RWS was temporarily shut down during acquisition of the 2020 through 2023 AEM data. The result was a quieter EM setting for these surveys, resulting in less filtering and interpolation than in 2019.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.3-3. Locations of the Decoupled and Removed Data (Red Lines) Along the AEM Flight Lines and the Data Used in the Inversion 4-10

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4.3.2.2 Resistivity Model Verification CSEM resistivity measurements are generally in close agreement with U.S. Geologic Survey induction (resistivity) logs collected from monitoring wells within the survey boundaries. This, combined with the good calibration with chloride samples from multi-layered monitoring wells, provides an independent check on the efficacy of the EM data processing method in estimating groundwater salinity concentrations within the study area.

Borehole induction logging was conducted by the USGS at each deep well within the TPGW series monitoring sites located within the survey area. The induction logs were acquired with a single frequency EM logging tool that measures the bulk resistivity of the earth materials and pore fluids up to approximately 1 meter (m) outside the well bore. Details regarding the borehole induction logging and the result for each site are published in Appendix J of the 2023 Turkey Point Annual Monitoring Report (FPL 2023). The induction logs provide a continuous record of localized (i.e., tens of centimeters surrounding the borehole) EM electrical resistivity with depth at each well where the induction log data were obtained.

The layer inversions (resistivity model) from the AEM data were compared to the induction log data to verify that the parameters chosen in the AEM inversion software were producing layer resistivities that are in general agreement with the borehole induction logs. However, there are several differences between the two methods that make direct alignment of the data technically infeasible. Therefore, care needs to be taken when comparing results from the borehole induction logs and the AEM layer resistivities, as comparing trends is appropriate rather than attempting to match absolute resistivity values. Factors that prevent direct comparisons of resistivity values between the two methods include the following:

Differences in measuring geometry. The AEM footprint is large compared to the data acquisition distances within centimeters of a borehole for induction logs. Accordingly, there are typically vertical differences between the location of the borehole screen and the associated AEM layer which provides data for the layer with thickness greater than the screened zone.

Lateral differences in data acquisition locations. Not all wells are located on flight lines; but several wells that were close to or within a few hundred feet of a flight line were used in the verification.

Uncalibrated borehole logging tool. The borehole logging tool is generally uncalibrated for the full range of resistivities measured in the survey area. Additionally, various logging tools have been used within the survey area leading to potential data biases.

AEM bulk resistivity inversion profiles were compared to induction logs obtained at wells TPGW-1, TPGW-2, TPGW-4, TPGW-5, TPGW-6, TPGW-12, TPGW-15, TPGW-17, 4-11

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary TPGW-18, TPGW-19 and TPGW-22 shown in Appendix F. Where a TPGW monitoring well induction log was performed near an AEM flight line profile, the induction log resistivity is shown on the profile using the same color scale as the AEM resistivity. The bulk resistivity inversion profiles along each flight line generally compare well with the borehole induction logs, indicating that the inversion has produced estimates of the variation of bulk resistivity versus depth comparable to values obtained in observation wells. Additionally, the induction logs and the corresponding AEM resistivity measurements near the monitoring wells indicate that the formation in those locations has become increasingly more resistive from 2018 through 2023.

Borehole video and lithology logs (JLA Geosciences, 2010; Wacker, 2010) from some of the monitoring boreholes installed in 2010 were reviewed. The video logs of TPGW-2 and TPGW-4 indicate that there is a change in lithology from approximately 26 to 30 feet below ground surface at those locations. This change is not apparent in TPGW-1, TPGW-5, TPGW-6, and TPGW-12, and TPGW-12 appears to have a dissolution cavity between -20 ft to about -35 ft below ground surface. The apparent differences in lithology and porosity across the compliance area very likely has an influence on the measurements of the AEM bulk resistivity and the borehole induction logs. A detailed discussion of the USGS induction log/AEM resistivity comparison and a comparison of 2023 vs 2018 resistivity for each layer is presented in the 2023 AGF Year 5 Survey Report (Appendix F).

4.3.3 Conversion of AEM Resistivity to Estimated Chloride Concentrations of Ground Water During the first four years of AEM data acquisition and processing, quarterly water quality data from the TPGW monitoring wells were used to develop an equation for conversion of AEM resistivity to equivalent groundwater chloride concentration. The calculations used the relationship established between laboratory samples for the TPGW wells and AEM resistivity (Table 4.3-2). The calibration of the AEM data was conducted using a two-step approach, similar to that presented in Fitterman and Prinos (2011) and Fitterman et al. (2012). First, a mathematical relationship was established between AEM resistivity and the resistivity of groundwater samples from discrete depth intervals in the TPGW monitoring wells (water resistivity is the inverse of specific conductance). The mean values of the AEM resistivity sounding located within a 175-m radius (574 ft) of each corresponding TPGW monitoring well were selected to develop a statistical range in bulk resistivities for the AEM model layer that was at an equivalent depth to the screened intervals in the TPGW wells.

Results from Year 1 to Year 4 AEM surveys indicate that there is year-to-year bias or drift in the AEM resistivity measurements due to slight differences in AEM instrumentation and data processing algorithms used each year. Additionally, there is statistical uncertainty in chloride estimates at unsampled locations due to the small set of locations where AEM resistivity values can be matched against measured chloride. In 2023, alternative approaches were evaluated to assess different ways to process, model, and analyze AEM resistivity data in order to better to account for underlying variability and possible year-to-year bias. A revised statistical approach was used to process, model, and analyze the Year 5 AEM data to fine tune chloride estimates and hypersaline plume volumes.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Table 4.3-2. June 2023 Water Quality Data from TPGW Wells Well Screen (from Top of Casing) Specific From To From To Cl Salinity Conductance Well ID (ft) (ft) (m) (m) (mg/L) (PSU) (µS/cm)

TPGW-1S 32.00 34.00 9.76 10.37 9,210 14.89 24,581 TPGW-1M 52.10 54.10 15.88 16.49 22,900 38.23 57,496 TPGW-1D 85.30 89.30 26.01 27.23 27,100 47.10 69,040 TPGW-2S 27.97 31.97 8.53 9.75 15,200 25.68 40,320 TPGW-2M 53.88 55.88 16.43 17.04 28,600 49.46 72,054 TPGW-2D 88.79 90.79 27.07 27.68 30,200 51.24 74,270 TPGW-4S 23.20 25.20 7.07 7.68 2,080 3.80 6,890 TPGW-4M 38.10 43.10 11.62 13.14 15,600 25.80 40,452 TPGW-4D 61.60 65.60 18.78 20.00 16,100 26.91 41,985 TPGW-5S 28.60 32.60 8.72 9.94 133 0.44 905 TPGW-5M 49.30 54.30 15.03 16.55 8,640 14.58 24,060 TPGW-5D 67.00 72.00 20.43 21.95 13,900 23.08 36,525 TPGW-6S 25.09 27.09 7.65 8.26 264 0.68 1,363 TPGW-6M 51.61 55.61 15.73 16.95 8,540 14.02 23,209 TPGW-6D 84.70 88.70 25.82 27.04 8,750 15.27 25,084 TPGW-12S 25.19 27.19 7.68 8.29 19,500 32.18 49,331 TPGW-12M 59.21 63.21 18.05 19.27 20,400 34.82 58,894 TPGW-12D 93.24 97.24 28.43 29.65 26,800 44.44 65,623 TPGW-15S 24.32 29.32 7.41 8.94 8,910 15.69 25,851 TPGW-15M 44.39 49.39 13.53 15.06 23,000 39.69 59,514 TPGW-15D 79.31 84.31 24.18 25.70 29,200 49.54 72,240 TPGW-17S 32.11 37.11 9.79 11.31 20,900 35.43 53,733 TPGW-17M 49.95 54.95 15.23 16.75 25,100 43.17 63,984 TPGW-17D 86.81 91.81 26.47 27.99 27,100 46.65 68,458 TPGW-18S 35.25 40.25 10.75 12.27 2,150 3.93 7,169 TPGW-18M 63.25 68.25 19.28 20.81 21,800 38.01 57,138 TPGW-18D 84.27 91.27 25.69 27.83 22,700 38.07 57,224 TPGW-19S 27.37 31.37 8.34 9.56 941 1.91 3,641 TPGW-19M 48.39 52.39 14.75 15.97 19,400 31.38 48,233 TPGW-19D 84.35 89.35 25.72 27.24 23,700 40.03 59,822 TPGW-22S 29.00 32.00 8.84 9.75 16,500 27.00 42,093 TPGW-22M 54.00 57.00 16.46 17.37 21,800 36.16 54,645 TPGW-22D 69.00 72.00 21.03 21.94 21,200 36.49 55,095 The revised statistical approach used in Year 5 (2023) statistical methodology relies on the highly correlated and consistent year-to year relationship between lab-measured chloride and lab-measured fluid resistivity (Figure 4.3-4) and consists of the following:

1. Normalizing the bulk AEM resistivity data using Archies Law (summarized below),

2. Producing bias adjusted chloride estimates across the compliance area using a Deming regression,

3. Converting/transforming the AEM resistivity measured at each sounding location to a chloride concentration, and 4-13

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary

4. Interpolating chloride concentration estimates to the gridded voxel model.

Figure 4.3-4. Log-Log Linear Regression Between Fluid Resistivity and Chloride The methodologies used in the Year 5 (2023) revised statistical approach are described in detail in Appendix F and G and are summarized below in Sections 4.3.4.

4.3.4 Year 2023 Chloride Conversion Archies Law is a well-known geophysical law (Glover, 2009) that describes the relationship between bulk resistivity of the formation and the resistivity of the fluids contained in the formation using porosity and a cementation factor:

=

where is bulk resistivity, is fluid resistivity, is porosity, and m is cementation factor.

The cementation factor describes the connectedness of the porosity within the formation; generally speaking, the higher the cementation factor the more connected the formation.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary By rearranging Archies Law and using estimates of porosity at each sampled well screen taken from the TetraTech groundwater transport model, an estimated well-screen-specific cementation factor for each sampled groundwater well screen location and each year was calculated using equations:

/

and

= (/)

()

where , the ratio between bulk and fluid resistivity, is known as the formation factor.

Due to the subsurface geology, the estimated cementation factors differ by depth zone. The shallower portions of the Biscayne aquifer exhibit dissolution porosity that becomes more clastic and less interconnected with depth (Figure 4.3-5). Assuming that the true cementation factor remains constant, then temporal changes in bulk resistivity associated with the rock matrix can be attributed to random error/variation in the resistivity measurement process and/or year-to-year calibration drift. Based on this, a statistical model to calculate corrected cementation factors accounting for the magnitude of the calibration bias was developed:

= + + +

0 Where is the corrected cementation factor, 0 is the overall average cementation factor across the compliance region, is the change in average cementation due to depth zone, is the change in average cementation due to year of sampling, and is the location-specific change in cementation independent of the effects of either depth zone or year of sampling. This model assumes that random error/variation due to either the AEM resistivity measuring process and/or the time/date of sampling (since the AEM survey only occurs once a year) averages out across depth zones and years for any specific location.

The corrected cementation factors were used to calculate bias adjusted AEM resistivity estimates for each sampled groundwater well screen and each monitoring year using Archies Law. A plot of the observed AEM resistivity versus the adjusted AEM resistivity estimates is shown in Figure 4.3-6.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.3-5. Variation in Cementation Factors (Mean +/- SD) By Depth Zone and Year Figure 4.3-6 Observed Versus Bias Adjusted AEM Resistivity 4-16

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Then, Deming regression was used to define the relationship between chloride concentrations and resistivity measured at each monitoring well. Deming regression was selected because it assumes that error occurs in both variables, and the same equation will be produced whether either variable is plotted on the X or Y axis. In this case, chloride levels were plotted against the bias adjusted AEM resistivity on a log-log scale. Deming regression coefficients are presented in Table 4.3-3.

Table 4.3-3 Year Specific Deming Regression Coefficients Each year-specific Deming regression equation allows calculation of a bulk AEM resistivity value at every sounding location within each layer of the inversion data for each year (2018 to 2023). Since the regression models are estimated on the log-log scale, they represent a non-linear transformation of the original data, and any back-transformation of estimates of the log-scale mean then results in some degree of transformation bias. To account for this transformation bias, a smearing estimate (Duan, 1983) was utilized, whereby the observed residuals () from the log-log scale regression line were leveraged to adjust for the anticipated degree of bias.

The resulting values are the year-specific chloride estimates, corrected for both AEM measurement and transformation bias. Because of the relatively small size of the data set, and in order to best represent the overall geophysical relationship between AEM resistivity and chloride along a broader range of the measurement scale, all of the available chloride-AEM resistivity pairs collected from 2018 through 2023 were used to calculate the 2023 bias adjusted chloride levels.

Finally, the bias-corrected chloride estimates in each inversion layer were interpolated to the gridded voxel model, indexed by grid cell locations for each depth layer and for each year. A voxel is a 3D grid cell, or volume element. Each voxel has lateral (x, y) dimensions of 328 ft x 328 ft (100 m x 100 m) and a thickness equivalent to the individual 3D AEM resistivity layers (Table 4.3-1). The bottom of layer 14 is at a depth of about 100 ft below land surface (30.3 m).

A local, inverse distance-weighted average of the nearest 5 neighboring soundings was used to estimate each voxel, meaning that the closest of five nearest neighbor soundings received the largest weights, while those further from the voxel were given less weight.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Because monitoring well data are constrained to the Biscayne aquifer, the calibrated equation relating AEM resistivity to groundwater chloride concentrations is applicable only to the data collected from the CA/CO network of monitoring wells. For this reason, use of this empirically derived relationship between AEM resistivity and chloride concentrations should not be applied to AEM resistivities from geologic units below the Biscayne aquifer not monitored under the CA/CO network.

4.4 BIAS-ADJUSTED CHLORIDE RESULTS 4.4.1 AEM Layers and High Flow Zones Bias adjusted chloride concentrations for the screened intervals of the TPGW monitoring wells for 2018 through 2023 are presented in Table 4.4-1 through Table 4.4-6 respectively. The monitoring wells within and surrounding Turkey Point are constructed into high permeability zones in the upper, middle, and lower Biscayne aquifer. As the elevations of the screens in the monitoring wells vary in depth and the elevations of the AEM layers are constant across the survey area, the AEM layers that represent the upper, middle, and lower flow zones of the Biscayne aquifer can vary. The upper flow zone is present in AEM layers 6 through 8, the middle flow zone is present in AEM layers 10 and 11, and the lower flow zone is present in AEM layers 12 through 14. The three AEM layers that include the most upper, middle, and lower monitoring well intervals are AEM layers 7, 10, and 14, respectively.

Table 4.4-1 Deming Regression Chloride Concentrations for 2018 - Measured versus Deming Estimated Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2018 TPGW-1D 13-14 28500 26609.0 26609.0 0.1425 1.8 1.48 2018 TPGW-1M 10 27700 28602.7 28602.7 0.1414 1.7 1.18 2018 TPGW-1S 8 19400 18496.7 18496.7 0.2018 2.4 1.68 2018 TPGW-2D 14 31300 44424.6 40000.0 0.1577 1.2 1.64 2018 TPGW-2M 10 29500 28602.7 28602.7 0.1339 1.7 1.18 2018 TPGW-2S 7 24800 33505.8 33505.8 0.1355 1.5 1.06 2018 TPGW-4D 11-12 14800 19519.0 19519.0 0.2429 2.3 2.89 2018 TPGW-4M 9 15100 28602.7 28602.7 0.2512 1.7 4.96 2018 TPGW-4S 6 2280 5461.0 5461.0 1.3501 6.3 7.14 2018 TPGW-5D 12 13100 13384.1 13384.1 0.2737 3.1 2.68 2018 TPGW-5M 10 11700 8355.9 8355.9 0.2932 4.5 2.75 2018 TPGW-5S 7 164 384.5 384.5 10.438 51.4 76.31 2018 TPGW-6D 13-14 8670 9697.4 9697.4 0.4138 4 4.31 2018 TPGW-6M 10 7970 3007.2 3007.2 0.4382 10.1 4.11 2018 TPGW-6S 6-7 313 428.3 428.3 6.5876 47.2 54.86 2018 TPGW-12D 14 24000 33505.8 33505.8 0.1533 1.5 1.82 4-18

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2018 TPGW-12M 11 20900 23290.9 23290.9 0.1692 2 3.66 2018 TPGW-12S 6 16500 30880.9 30880.9 0.2112 1.6 1.76 2018 TPGW-15D 13 28800 33505.8 33505.8 0.1356 1.5 1.41 2018 TPGW-15M 9-10 30000 27573.6 27573.6 0.1398 1.75 4.13 2018 TPGW-15S 6-7 20100 12367.1 12367.1 0.1977 3.3 1.54 2018 TPGW-17D 14 28600 44424.6 40000.0 0.1427 1.2 1.70 2018 TPGW-17M 10 29300 49589.7 40000.0 0.1379 1.1 1.29 2018 TPGW-17S 8 24900 49589.7 40000.0 0.1585 1.1 1.23 2018 TPGW-18D 13-14 26400 24048.4 24048.4 0.1599 1.95 1.56 2018 TPGW-18M 11-12 25200 34972.9 34972.9 0.1648 1.45 1.22 2018 TPGW-18S 8-9 14200 14250.1 14250.1 0.2790 2.95 2.32 2018 TPGW-19D 13-14 26800 15221.8 15221.8 0.1648 2.8 1.72 2018 TPGW-19M 10 26000 18496.7 18496.7 0.1707 2.4 4.08 2018 TPGW-19S 7 1830 5461.0 5461.0 1.6145 6.3 14.43 Meas. CL (mg/L) - Borehole measured chloride concentration, Est. CL (mg/L) - 2023 Deming-estimated chloride concentrations, Est. CL clipped (mg/L) - Refers to clipping the estimated chloride concentrations greater than 40,000 mg/L to 40,000 mg/L RhoW (ohm-m) - Borehole-measured fluid resistivity RhoAEM (ohm-m) - AEM inverted earth model resistivity RhoA-Corr (ohm-m) -Bias-corrected estimate of RhoAEM Table 4.4-2 Deming Regression Chloride Concentrations for 2019 - Measured versus Deming Estimated Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2019 TPGW-1D 13-14 29100 28321.2 28321.2 0.1401 1.555 1.52 2019 TPGW-1M 10 28300 31393.3 31393.3 0.1409 1.44 1.12 2019 TPGW-1S 8 11000 17573.6 17573.6 0.3295 2.22 2.18 2019 TPGW-2D 14 31800 40083.7 40000.0 0.1310 1.2 1.43 2019 TPGW-2M 10 30600 25131.3 25131.3 0.1345 1.7 1.13 2019 TPGW-2S 7 23800 36380.6 36380.6 0.1664 1.29 1.04 2019 TPGW-4D 11-12 16000 11281.8 11281.8 0.2365 3.09 2.94 2019 TPGW-4M 9 15200 22602.1 22602.1 0.2431 1.84 4.50 2019 TPGW-4S 6 1640 3770.2 3770.2 1.8126 7 7.99 2019 TPGW-5D 12 13600 8611.0 8611.0 0.2714 3.78 2.77 2019 TPGW-5M 10 12300 12005.2 12005.2 0.3000 2.95 2.68 2019 TPGW-5S 7 142 260.9 260.9 11.1111 51.34 65.40 2019 TPGW-6D 13-14 8970 9528.4 9528.4 0.4067 3.505 4.43 2019 TPGW-6M 10 8260 3424.9 3424.9 0.4263 7.52 3.81 4-19

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2019 TPGW-6S 6-7 331 343.8 343.8 6.5020 41.79 42.98 2019 TPGW-17D 14 30300 47940.0 40000.0 0.1382 1.05 1.72 2019 TPGW-17M 10 28600 60745.3 40000.0 0.1433 0.88 1.28 2019 TPGW-17S 8 24700 31687.9 31687.9 0.1633 1.43 1.02 2019 TPGW-18D 13-14 25400 25841.9 25841.9 0.1635 1.665 1.67 2019 TPGW-18M 11-12 24800 31987.4 31987.4 0.1688 1.42 1.20 2019 TPGW-18S 8-9 7680 15108.4 15108.4 0.4774 2.485 3.16 2019 TPGW-19D 13-14 24700 12115.1 12115.1 0.1644 2.93 1.79 2019 TPGW-19M 10 22000 24548.9 24548.9 0.1797 1.73 4.02 2019 TPGW-19S 7 3330 3289.4 3289.4 0.9957 7.75 7.01 Meas. CL (mg/L) - Borehole measured chloride concentration, Est. CL (mg/L) - 2023 Deming-estimated chloride concentrations, Est. CL clipped (mg/L) - Refers to clipping the estimated chloride concentrations greater than 40,000 mg/L to 40,000 mg/L RhoW (ohm-m) - Borehole-measured fluid resistivity RhoAEM (ohm-m) - AEM inverted earth model resistivity RhoA-Corr (ohm-m) -Bias-corrected estimate of RhoAEM Table 4.4-3 Deming Regression Chloride Concentrations for 2020 - Measured versus Deming Estimated Monitoring AEM Est . Cl RhoA-Year Meas. Cl Est.Cl RhoW RhoAEM Well Layer clipped Corr 2020 TPGW-1D 13-14 28500 24263.0 24263.0 0.1422 1.675 1.53 2020 TPGW-1M 10 26700 31619.6 31619.6 0.1500 1.39 1.12 2020 TPGW-1S 8 6440 8418.5 8418.5 0.5587 3.53 2.99 2020 TPGW-2D 14 30800 39898.7 39898.7 0.1327 1.18 1.43 2020 TPGW-2M 10 28500 30072.1 30072.1 0.1398 1.44 1.11 2020 TPGW-2S 7 16900 23560.9 23560.9 0.2287 1.71 1.16 2020 TPGW-4D 11-12 15900 8521.1 8521.1 0.2333 3.5 2.87 2020 TPGW-4M 9 15100 28378.6 28378.6 0.2458 1.5 4.18 2020 TPGW-4S 6 1180 4371.9 4371.9 2.4120 5.6 9.00 2020 TPGW-5D 12 15300 8284.9 8284.9 0.2737 3.57 2.77 2020 TPGW-5M 10 12100 10606.1 10606.1 0.3304 3 2.77 2020 TPGW-5S 7 151 226.6 226.6 10.6952 45.03 51.58 2020 TPGW-6D 13-14 9620 9384.6 9384.6 0.4004 3.27 4.32 2020 TPGW-6M 10 9490 3641.0 3641.0 0.4239 6.37 3.56 2020 TPGW-6S 6-7 346 236.8 236.8 6.0496 43.655 32.34 2020 TPGW-17D 14 26800 55103.6 40000.0 0.1460 0.94 1.80 2020 TPGW-17M 10 27700 45244.5 40000.0 0.1427 1.08 1.20 2020 TPGW-17S 8 21000 34026.8 34026.8 0.1778 1.32 0.90 4-20

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Monitoring AEM Est . Cl RhoA-Year Meas. Cl Est.Cl RhoW RhoAEM Well Layer clipped Corr 2020 TPGW-18D 13-14 23300 24160.5 24160.5 0.1654 1.68 1.67 2020 TPGW-18M 11-12 24400 25219.6 25219.6 0.1696 1.63 1.14 2020 TPGW-18S 8-9 4780 15001.8 15001.8 0.7358 2.35 3.93 2020 TPGW-19D 13-14 20800 10193.6 10193.6 0.1659 3.085 1.79 2020 TPGW-19M 10 19300 30371.2 30371.2 0.1841 1.43 3.76 2020 TPGW-19S 7 1810 2373.6 2373.6 1.5205 8.61 8.59 Meas. CL (mg/L) - Borehole measured chloride concentration, Est. CL (mg/L) - 2023 Deming-estimated chloride concentrations, Est. CL clipped (mg/L) - Refers to clipping the estimated chloride concentrations greater than 40,000 mg/L to 40,000 mg/L RhoW (ohm-m) - Borehole-measured fluid resistivity RhoAEM (ohm-m) - AEM inverted earth model resistivity RhoA-Corr (ohm-m) -Bias-corrected estimate of RhoAEM Table 4.4-4 Deming Regression Chloride Concentrations for 2021 - Measured versus Deming Estimated Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2021 TPGW-1D 13-14 27400 21962.8 21962.8 0.1426 1.725 1.54 2021 TPGW-1M 10 24900 25871.6 25871.6 0.1584 1.53 1.20 2021 TPGW-1S 8 12600 13991.2 13991.2 0.3005 2.4 1.68 2021 TPGW-2D 14 30500 38664.0 38664.0 0.1326 1.14 1.43 2021 TPGW-2M 10 28300 23337.2 23337.2 0.1359 1.65 1.09 2021 TPGW-2S 7 15600 22226.3 22226.3 0.2166 1.71 1.15 2021 TPGW-4D 11-12 14900 9248.4 9248.4 0.2403 3.25 2.97 2021 TPGW-4M 9 14200 24338.6 24338.6 0.2466 1.6 4.26 2021 TPGW-4S 6 2490 4998.9 4998.9 1.1762 5.1 4.55 2021 TPGW-5D 12 13000 7863.5 7863.5 0.2724 3.66 2.76 2021 TPGW-5M 10 10300 13018.9 13018.9 0.3272 2.53 2.77 2021 TPGW-5S 7 154 271.9 271.9 10.5152 43.02 53.00 2021 TPGW-6D 13-14 8870 9095.2 9095.2 0.3992 3.29 4.31 2021 TPGW-6M 10 8500 4193.7 4193.7 0.4216 5.8 3.58 2021 TPGW-6S 6-7 328 317.7 317.7 5.9137 38.385 33.13 2021 TPGW-17D 14 27400 45614.8 40000.0 0.1434 1.01 1.77 2021 TPGW-17M 10 27400 43258.7 40000.0 0.1488 1.05 1.26 2021 TPGW-17S 8 21800 31325.4 31325.4 0.1804 1.33 0.96 2021 TPGW-18D 13-14 21000 23729.0 23729.0 0.1681 1.63 1.70 2021 TPGW-18M 11-12 20500 22405.0 22405.0 0.1709 1.7 1.16 2021 TPGW-18S 8-9 3130 14111.5 14111.5 1.0119 2.385 5.67 2021 TPGW-19D 13-14 23400 10779.9 10779.9 0.1642 2.905 1.77 4-21

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2021 TPGW-19M 10 20100 31980.2 31980.2 0.1932 1.31 4.00 2021 TPGW-19S 7 309 2032.1 2032.1 6.4935 9.86 38.53 2021 TPGW-22D 11 20600 12542.7 12542.7 0.1780 2.6 2.36 2021 TPGW-22M 10 20800 19387.3 19387.3 0.1818 1.89 1.54 2021 TPGW-22S 7 13900 9778.6 9778.6 0.2395 3.12 1.21 Meas. CL (mg/L) - Borehole measured chloride concentration, Est. CL (mg/L) - 2023 Deming-estimated chloride concentrations, Est. CL clipped (mg/L) - Refers to clipping the estimated chloride concentrations greater than 40,000 mg/L to 40,000 mg/L RhoW (ohm-m) - Borehole-measured fluid resistivity RhoAEM (ohm-m) - AEM inverted earth model resistivity RhoA-Corr (ohm-m) -Bias-corrected estimate of RhoAEM Table 4.4-5 Deming Regression Chloride Concentrations for 2022 - Measured versus Deming Estimated Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2022 TPGW-1D 13-14 26700 19851.7 19851.7 0.1430 1.88 1.57 2022 TPGW-1M 10 23700 25902.0 25902.0 0.1551 1.54 1.06 2022 TPGW-1S 8 9650 14334.1 14334.1 0.3378 2.4 2.30 2022 TPGW-2D 14 29000 37795.9 37795.9 0.1327 1.16 1.46 2022 TPGW-2M 10 28500 34955.0 34955.0 0.1351 1.23 0.98 2022 TPGW-2S 7 15300 15439.1 15439.1 0.2278 2.27 1.46 2022 TPGW-4D 11-12 14700 7645.6 7645.6 0.2351 3.845 2.95 2022 TPGW-4M 9 14300 21842.3 21842.3 0.2419 1.75 3.63 2022 TPGW-4S 6 2520 5687.6 5687.6 1.0970 4.8 4.95 2022 TPGW-5D 12 12600 7502.1 7502.1 0.2710 3.9 2.79 2022 TPGW-5M 10 9540 8868.9 8868.9 0.3451 3.44 2.63 2022 TPGW-5S 7 138 498.3 498.3 10.7181 29.8 64.79 2022 TPGW-6D 13-14 8290 8409.5 8409.5 0.3990 3.58 4.38 2022 TPGW-6M 10 7870 4813.3 4813.3 0.4097 5.44 3.13 2022 TPGW-6S 6-7 263 467.7 467.7 6.8823 31.25 46.81 2022 TPGW-12D 14 24700 29412.6 29412.6 0.1500 1.4 1.89 2022 TPGW-12M 11 19900 29412.6 29412.6 0.1843 1.4 3.01 2022 TPGW-12S 6 18400 30874.2 30874.2 0.1955 1.35 1.33 2022 TPGW-15D 13 27600 36530.6 36530.6 0.1376 1.19 1.51 2022 TPGW-15M 9-10 25700 23914.7 23914.7 0.1470 1.635 3.18 2022 TPGW-15S 6-7 12800 3682.3 3682.3 0.2702 6.65 1.73 2022 TPGW-17D 14 26500 42624.2 40000.0 0.1436 1.06 1.80 2022 TPGW-17M 10 24400 43720.8 40000.0 0.1541 1.04 1.18 4-22

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Monitoring AEM Meas. Est . Cl RhoA-Year Est.Cl RhoW RhoAEM Well Layer Cl clipped Corr 2022 TPGW-17S 8 20300 29412.6 29412.6 0.1793 1.4 1.15 2022 TPGW-18D 13-14 22000 21676.9 21676.9 0.1693 1.76 1.74 2022 TPGW-18M 11-12 19600 22526.3 22526.3 0.1677 1.71 1.04 2022 TPGW-18S 8-9 2230 16395.1 16395.1 1.2005 2.17 8.16 2022 TPGW-19D 13-14 22800 9547.5 9547.5 0.1641 3.255 1.80 2022 TPGW-19M 10 19200 29134.7 29134.7 0.1853 1.41 3.31 2022 TPGW-19S 7 1160 1940.7 1940.7 2.1734 10.75 15.76 2022 TPGW-22D 11 20400 12882.9 12882.9 0.1769 2.6 2.39 2022 TPGW-22M 10 20900 21595.1 21595.1 0.1783 1.765 1.36 2022 TPGW-22S 7 14900 10102.3 10102.3 0.2317 3.12 1.40 Meas. CL (mg/L) - Borehole measured chloride concentration, Est. CL (mg/L) - 2023 Deming-estimated chloride concentrations, Est. CL clipped (mg/L) - Refers to clipping the estimated chloride concentrations greater than 40,000 mg/L to 40,000 mg/L RhoW (ohm-m) - Borehole-measured fluid resistivity RhoAEM (ohm-m) - AEM inverted earth model resistivity RhoA-Corr (ohm-m) -Bias-corrected estimate of RhoAEM Table 4.4-6 Deming Regression Chloride Concentrations for 2023 - Measured versus Deming Estimated Monitoring AEM Est . Cl RhoA-Year Meas. Cl Est.Cl RhoW RhoAEM Well Layer clipped Corr 2023 TPGW-1D 13-14 27100 25095.4 25095.4 0.1448 1.665 1.57 2023 TPGW-1M 10 22900 25395.8 25395.8 0.1739 1.65 1.17 2023 TPGW-1S 8 9210 9890.0 9890.0 0.4068 3.38 2.97 2023 TPGW-2D 14 30200 37775.0 37775.0 0.1346 1.22 1.46 2023 TPGW-2M 10 28600 31819.8 31819.8 0.1388 1.39 0.98 2023 TPGW-2S 7 15200 16040.6 16040.6 0.2480 2.34 1.70 2023 TPGW-4D 11-12 16100 10628.0 10628.0 0.2382 3.2 2.95 2023 TPGW-4M 9 15600 22162.9 22162.9 0.2472 1.83 3.61 2023 TPGW-4S 6 2080 4579.3 4579.3 1.4514 6.07 6.91 2023 TPGW-5D 12 13900 8971.6 8971.6 0.2738 3.64 2.79 2023 TPGW-5M 10 8640 11081.2 11081.2 0.4156 3.1 3.11 2023 TPGW-5S 7 133 291.1 291.1 11.0497 49.34 71.31 2023 TPGW-6D 13-14 8750 8537.2 8537.2 0.3987 3.78 4.32 2023 TPGW-6M 10 8540 5909.6 5909.6 0.4309 5 3.23 2023 TPGW-6S 6-7 264 335.4 335.4 7.3368 44.3 53.50 2023 TPGW-15D 13 29200 31521.2 31521.2 0.1384 1.4 1.50 2023 TPGW-15M 9-10 23000 19089.2 19089.2 0.1680 2.05 3.53 2023 TPGW-15S 6-7 8910 6446.7 6446.7 0.3868 4.68 2.65 4-23

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Monitoring AEM Est . Cl RhoA-Year Meas. Cl Est.Cl RhoW RhoAEM Well Layer clipped Corr 2023 TPGW-17D 14 27100 47194.8 40000.0 0.1461 1.03 1.81 2023 TPGW-17M 10 25100 43808.3 40000.0 0.1563 1.09 1.17 2023 TPGW-17S 8 20900 30654.4 30654.4 0.1861 1.43 0.89 2023 TPGW-18D 13-14 22700 23329.3 23329.3 0.1748 1.76 1.78 2023 TPGW-18M 11-12 21800 25194.8 25194.8 0.1750 1.66 1.06 2023 TPGW-18S 8-9 2150 14437.9 14437.9 1.3949 2.535 9.00 2023 TPGW-19D 13-14 23700 10760.5 10760.5 0.1672 3.17 1.81 2023 TPGW-19M 10 19400 27339.9 27339.9 0.2073 1.56 3.60 2023 TPGW-19S 7 941 1914.7 1914.7 2.7465 11.78 20.03 2023 TPGW-22D 11 21200 12609.0 12609.0 0.1815 2.81 2.41 2023 TPGW-22M 10 21800 23242.4 23242.4 0.1830 1.765 1.37 2023 TPGW-22S 7 16500 11272.0 11272.0 0.2376 3.06 1.53 2023 TPGW-23D 13-14 24100 24898.5 24898.5 0.1632 1.675 2.02 2023 TPGW-23M 11 22600 23862.8 23862.8 0.1817 1.73 2.89 2023 TPGW-23S 6-7 11700 13224.4 13224.4 0.2944 2.71 2.15 Meas. CL (mg/L) - Borehole measured chloride concentration, Est. CL (mg/L) - 2023 Deming-estimated chloride concentrations, Est. CL clipped (mg/L) - Refers to clipping the estimated chloride concentrations greater than 40,000 mg/L to 40,000 mg/L RhoW (ohm-m) - Borehole-measured fluid resistivity RhoAEM (ohm-m) - AEM inverted earth model resistivity RhoA-Corr (ohm-m) -Bias-corrected estimate of RhoAEM 4.4.2 Volumetric Determination Methodologies and Spatial Comparison As described in Section 4.3.3 and 4.3.4, the bias adjusted concentrations were interpolated to a voxel grid with horizontal dimensions of 100 m x 100 m for each grid cell. The thickness of each cell is the thickness of a given AEM layer. The voxels with estimated chloride values

>19,000 mg/L can be counted, and their volumes calculated. This allows an estimate of the volume of the hypersaline plume (>19,000 mg/L) to be made. This comparison of hypersaline volume can be made layer by layer or for the entire thickness of the Biscayne aquifer. Because the AEM layer geometry and the volumes of the voxels increase with depth, care should be exercised when comparing the percent reduction of the volume of the aquifer saturated with hypersaline water for different layers. The lower AEM layers have substantially greater volume per voxel than the shallowest layers. Revised hypersaline plume volume estimates were calculated using the 2018 and 2023, and the resulting proportion of hypersaline voxels within each model layer were calculated for 2018 through 2023 (Years 1 through 5). Revised hypersaline plume volume estimates are presented in Table 4.4-7, and Figure 4.4-1 shows the overall trend in the percentage of hypersaline chloride voxels by layer from 2018 through 2023.

The spatial extent of hypersaline earth materials is determined by locating the westernmost and northernmost positions of adjacent voxels along each flight line. The locations of each edge position are manually identified by AGF; and the contour of the 19,000 mg/L chloride extent on 4-24

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary a layer-by-layer basis is produced. To assess changes in the orientation of the extent hypersalinity in the Biscayne aquifer after five years of RWS operations, the positions of both the 2018 and 2023 19,000 mg/L contours are produced for each AEM layer. Color-flood maps that illustrate the 2D plan view variation in the bias adjusted chloride concentrations (i.e.,

representation of groundwater contours utilizing AEM) for 2018 and 2023 are provided in Appendix F. Contour maps were also created using the bias adjusted chloride concentrations in order to compare the location of the 19,000 mg/L contour in the 2018 baseline results with the location of the 19,000 mg/L contour for Year 5 (2023). These comparisons are shown for each AEM layer in Appendix F and below in Section 4.5.2.

Table 4.4-7 Bias Adjusted Chloride Concentration Volumes for 2018 and 2023 (in cubic meters).

AEM Layer Revised Hypersaline Plume Volume Estimates in Cubic Meters Year 2018 2019 2020 2021 2022 2023 1 1,690,000 0 0 0 0 0 2 1,870,000 1,232,000 0 0 0 0 3 1,608,000 2,040,000 1,788,000 0 780,000 48,000 4 966,000 2,394,000 2,506,000 1,456,000 2,506,000 2,478,000 5 3,480,000 1,155,000 3,720,000 3,960,000 5,235,000 4,605,000 6 13,719,000 8,738,000 7,837,000 7,786,000 3,502,000 6,766,000 7 27,189,000 23,541,000 16,739,000 11,077,000 4,256,000 10,374,000 8 30,912,000 27,720,000 22,155,000 13,062,000 25,389,000 15,372,000 9 50,784,000 44,114,000 54,533,000 44,091,000 62,629,000 51,083,000 10 86,684,000 86,320,000 88,582,000 79,482,000 84,890,000 84,682,000 11 118,059,000 99,383,000 89,987,000 77,981,000 77,894,000 92,104,000 12 111,648,000 94,176,000 85,248,000 75,424,000 77,152,000 86,496,000 13 91,385,000 84,665,000 68,635,000 61,985,000 58,485,000 67,585,000 14 58,968,000 57,447,000 53,469,000 49,608,000 52,026,000 52,884,000 All Layers 598,962,000 532,925,000 495,199,000 425,912,000 454,744,000 474,477,000 4-25

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.4-1 Trends in Bias Adjusted Hypersaline Chloride 4.4.3 Statistical Significance of Plume Volume Changes 2018 to 2023 Additional analyses of statistically significant changes in the volume of hypersaline water from 2018-2023 in the compliance area, as defined by the AEM data, has been performed using permutation testing and bootstrapping and are summarized below by Kirk Cameron, PhD. Dr.

Cameron is the principal author of the 2009 Unified Guidance for the Statistical Analysis of Groundwater Monitoring Data (EPA 2009) and Principal for MacStat Consulting, Ltd.

If the RWS is ineffective or the AEM method has large errors in estimated chloride, then the year-by-year changes in the AEM-derived hypersaline volume within the compliance area will be random and statistically unrelated to the time of pumping by the RWS. This null hypothesis, that there is no statistically significant change in the volume of the hypersaline volume with time, can be tested statistically. Two methods have been applied to the voxel volume data to test the null hypothesis: permutation testing and bootstrap estimation. The data used in these analyses are the gridded chloride voxels derived from bias adjusted chloride concentrations values, as summarized in Section 4.3.3 and 4.3.4 and described in detail in the Appendix G. A summary of the Permutation Testing and Bootstrapping Estimation are also included in Appendix H.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4.4.3.1 Permutation Testing Permutation tests were first introduced by two early pioneers in the statistics field, Fisher (1935) and Pitman (1937). Permutation tests are also known as randomization tests, involving a hypothetical calculation of the possible ways in which a data set can be randomly rearranged, and then comparing the observed arrangement to the set of possible rearrangements, to assess the level of statistical significance.

Permutation testing and bootstrap estimation are highly empirical, computationally intensive techniques. Neither one requires fitting or identification of exact statistical models. The most critical assumption relates instead to the overall data generation process. In order to compare the extent of the hypersaline plume across years, it is assumed that the data generating mechanism remains essentially the same with each year consisting of the steps described above. Then, regardless of the overall level of statistical uncertainty, under a null hypothesis of no actual change in plume extent or volume, one would expect year-to-year differences to be random, e.g.,

some years showing the number of hypersaline voxels lower and some years higher, but not trending over time or space in a particular direction. If, instead, the hypersaline plume is shrinking (or growing), the pattern of change across voxels from year to year will tend to exhibit a trend; and that trend can be positively identified as statistically significant using a combination of permutation testing and bootstrap estimates.

When comparing two or more groups of data, the general algorithm for conducting a permutation test is based on a straightforward idea: under the null hypothesis of no difference between the groups (often representing a hypothesis of no physical difference between the underlying populations), the observations from each group should be exchangeable. That is, random shuffling of the measurements between the groups should not affect the observed difference. Or, from another perspective, random relabeling of the observations (i.e., renaming elements of group 1 as group 2, group 3, etc.) should not change the magnitude of difference between the groups.

In practice, a permutation test involves the following steps:

1. Select an appropriate test statistic (t) to numerically gauge any difference between the groups.

2. Calculate the test statistic for the observed data as collected (t0).

3. Enumerate all (if feasible) or a large, randomly selected subset of the possible group label rearrangements (permutations).

4. Compute (t) on each permuted version of the data to construct the permutation distribution.

5. Compare t0 to the permutation distribution to determine what fraction (p) of the permuted statistics t exhibits a group difference as or more extreme than t0. This fraction is the p value of the test.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary

6. If the p value (p) is large (e.g., p 0.05 or p 0.01), accept the null hypothesis of no group difference; but if p is small (e.g., p < 0.05 or p < 0.01), declare a statistically significant difference.

To implement permutation testing for the Turkey Point RWS, the only exchangeable voxels are those with the same spatial coordinates but estimated in different years. That is, the same voxel estimated in, say, 2018, can be randomly swapped with its paired counterpart in 2019, 2021, and so on; but it cannot be swapped with a different voxel from one of those successive years.

Consequently, the strategy tailored to the Turkey Point remediation is denoted as a spatial permutation test and looks akin to a kind of paired, two-sample test, where the natural pairing occurs between identically located voxels estimated in different years.

The steps for the spatial permutation testing are similar to those of a general permutation test, but with specific adjustments:

1. Define hypersaline chloride volume as the proportion of voxels within the study or comparison area of interest with chloride above 19,000 mg/L. Select year-to-year percentage change in hypersaline volume as the test statistic (t).

2. Compute the observed percentage change (t0) in hypersaline volume for each comparison of interest, e.g., baseline (2018) versus 2019, 2020, 2021, 2022, and/or 2023 for the overall hypersaline plume, any specific depth layer of the plume, or any subarea of the site.

3. For each comparison, generate a large number (e.g., 10,000) of random spatial permutations of the data (i.e., by randomly swapping identical voxels between the years being compared), and then compute t on each permutation to construct the permutation distribution for that case.

4. Compare t0 to the distribution of t to compute the p value and assess the statistical significance of each desired comparison.

The results of the spatial permutation testing algorithm were computed for the chloride voxel models from 2018 compared to years 2019-2023. The comparisons of interest were changes in the overall hypersaline plume proportion, as well as similar changes calculated separately for each depth layer. For the overall plume, the observed relative drop in hypersaline volume from the baseline year of 2018 was 11% in 2019, 17.3% in 2020, 28.9% in 2021, 24.1% in 2022, and 20.8% in 2023. These observed changes were very strongly different from the respective permutation distributions, so much so that the p values in all cases were essentially zero. These results indicate that there has been an overall decrease in hypersaline plume volumes since 2018; however, plume reduction estimates appear to be leveling off in 2022 and 2023. Statistically significant increases were observed in layers 4 and 5 that were documented in prior reports. The source of hypersalinity in these shallow layers was from evaporation of bay water transported inland northeast of the Turkey Point Plant by Hurricane Irma discussed in below in Section 4.5.1.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary The decreases observed in hypersaline plume volumes produced in these evaluations differ from those reported in prior RAASR reports due to the revised statistical methodology to produce the bias adjusted chloride concentrations. Previous plume volume estimates were likely understated, resulting in a higher percentage of hypersaline plume reduction stated in previous reports than actually occurred.

4.4.3.2 Bootstrap Estimation Bootstrapping was first introduced in the late 1970s (Efron 1979; Efron and Tibshirani 1986).

The flexibility and usefulness of bootstrapping has made it commonly employed by statisticians.

While permutation tests are mostly limited to group comparisons, bootstrapping can be applied to a wide variety of problems, including estimates of statistical variation from a single group or population. The bootstrap is especially powerful in constructing confidence intervals on test statistics for which the underlying statistical model is complex or unknown. As such, bootstrapping is often employed as a nonparametric technique when it may be difficult or impossible to fit the underlying data to a standard statistical distribution/model. The core idea behind the bootstrap is that the observed data can be assumed to adequately represent and substitute for the underlying, unknown population. Any statistical model must assume that the collected data are in some sense representative of the underlying population from which the observations came. But bootstrapping takes this assumption a step further by recognizing that the empirical (observed) distribution (or density) can be repeatedly resampled in order to mimic what would occur if access were available to the true distribution, and not simply to its empirical representative. In the simplest case, a nonparametric percentile bootstrap confidence interval around a desired statistic (t) can be computed as follows:

1. Select an appropriate (test) statistic (t) to summarize the desired population characteristic.

2. Note the sample size (n) of the observed data.

3. Compute t for the observed sample data, yielding the observed statistic (t0).

4. Construct a large number of bootstrap samples (B) by repeatedly resampling n observations with replacement from the observed data.

5. Compute t on each bootstrap sample B, leading to the bootstrap distribution of t.

6. Select a confidence level, 1 .

7. Calculate lower and upper percentiles of the bootstrap distribution so that the range between the percentiles covers a proportion of 1 of the total bootstrap density (e.g.,

for 95% confidence, compute the 2.5th and 97.5th percentiles).

Results of bootstrap estimation for the Turkey Point RWS are shown on Figure 4.4-2 which presents the calculated 99% bootstrap confidence intervals around the proportion of hypersaline chloride in each of the years 2018-2023, both overall and for each depth layer separately, using 10,000 bootstrap samples in each calculation.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary The trend in decreased overall hypersalinity is evident as well as the general tightness of the confidence intervals. These results are consistent with the permutation testing outcomes; but instead of providing a p value, they show a range of statistical uncertainty around each estimate.

Figure 4.4-2. Bootstrapped Trend in Percent Hypersaline Plume Volume by Layer Per Year 4.4.3.3 Results of Statistical Tests The probability that the observed changes in plume volume with time are random (as indicated by the p value) is much less than 0.001 for the full plume volume and AEM layers 1-3, 6-8, and 11-14. Thus, the null hypothesis of no reduction in plume volume is rejected. Layers 4 and 5 show an increase in chloride as a result of tidal inundation in 2017 during Hurricane Irma in the coastal area north of the CCS bounded by the Turkey Point Power Plant access road and the L-31E berm. These waters were concentrated by evaporation and moved downward from 2018-2023 through layers 1-3 to layers 4 and 5. Layers 9 and 10 also show a slight increase in chloride concentration.

Figure 4.4-2 shows the hypersaline plume volume percentage change by layer. Again, layers 4,5, and 9 show an increase in plume volume from 2018-2023 in the coastal area north of the CCS.

The largest plume volume increase in layer 9 was observed in 2022 with only an increase of less than one percent in 2023.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary In summary, the statistical testing of the changes in the volume of the hypersaline plume, both overall and by layer, demonstrates that the changes are highly significant statistically. This demonstrates that the RWS is effectively reducing the volume of the hypersaline plume, and that the AEM results are producing statistically significant estimates of the change in plume volume from year to year.

4.5 DISCUSSION OF FINDINGS Results of the AEM surveys indicate that the volume of hypersaline water in the compliance area has decreased from 2018 through 2023 to varying degrees. There remains un-resolved annual variance in the volumetric estimates of hypersalinity within the compliance area from year to year as shown by reduction from 2018 through 2021 followed by calculated increases in volume in 2022 and 2023.

However, the calculated increase in hypersalinity since 2021 directly conflicts with monitoring well data and calibrated modeling results for years 2022 and 2023. Despite the variability in volumes, the results mirror the modeling and monitoring findings that the plume has shown a statistically valid reduction in volumetric extent in the upper and middle portions of the aquifer during the first five years of remediation 4.5.1 Natural Occurrence of Hypersaline Water Two sources of hypersaline groundwater occur within the AEM survey area adjacent to the CCS.

Per the groundwater model, the predominant source is CCS sourced groundwater while the other source is naturally occurring evaporated seawater that originates in the coastal wetland margins (referred to as the white zone) and documented by USGS (Prinos et al. 2014). Salinities exceeding 40 PSU (>22,000 mg/L) have been documented to occur in coastal waters in western Florida Bay and Taylor River, well outside of any influences from the CCS (SFNRC 2012), and north and south of the CCS. Hypersaline surface water with fluid densities greater than underlying groundwater will sink into groundwater, resulting in both shallow and deep expressions of hypersaline groundwater. This is significant to the RWS remediation assessment, as the CA and CO do not require FPL to extract naturally occurring hypersaline groundwater.

Fitterman et al. (2012) used helicopter electromagnetic (HEM) surveys to map the distribution of saline groundwater in the C-111 and Model Lands basin areas of southeast MDC. The HEM data were presented as resistivity depth profiles. Comparison of geophysically determined formation resistivity and salinity concentrations from well samples (Fitterman and Prinos 2011) shows that formation resistivities of 1-2 ohm-m represent geologic units saturated with groundwater close to or at normal seawater chloride concentrations of 19,000 mg/L. Formation resistivities with values of 1 ohm-m or less represent hypersaline groundwater with chlorinity greater than 19,000 mg/L. Fitterman et al.s (2012) HEM data show that at a depth of approximately 17 ft (5 m), hypersaline groundwater is present between Card Sound Road and U.S. Highway 1 (US 1) in a coast-parallel band 4,000 to 6,000 ft wide. Hydrologically, the hypersaline groundwater in this coastal band is not from the CCS as there is no mechanism for coast-parallel flow of hypersaline groundwater from the CCS southwest past US 1. This hypersaline water corresponds to a coast-parallel zone of lower vegetative density in the coastal 4-31

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary wetlands as viewed from satellite images. It is common in coastal wetlands for evaporation of seawater to form hypersaline groundwater that moves downward into the sediments under a density gradient (Prinos et al. 2014). Salinities in shallow groundwater in coastal wetlands can reach 60-100 PSU (34,000-56,000 mg/L) (Stringer et al. 2010) and will migrate downward due to the increased density as compared to normal seawater. Close to the coast, evaporation of seawater can create a wide band of hypersaline groundwater. The HEM data of Fitterman et al.

(2012) suggest that this band of naturally created hypersaline groundwater extends to the base of the Biscayne aquifer between Card Sound Road and southwest past US 1. It is likely that this band of naturally occurring hypersaline water extended northward along the coast prior to construction of the CCS in the early 1970s at Turkey Point.

4.5.1.1 Shallow Hypersaline Occurrence North of the Cooling Canal System A shallow zone of >19,000 mg/L chloride porewater occurs north of Palm Drive and east of the L-31E levee. The shallow zone of hypersalinity was observed in the 2018 baseline survey, which was conducted approximately six months after the Hurricane Irma storm surge of 3-5 ft inundated the costal reaches of the Model Lands basin. Seawater that flooded the coastal wetlands up to the L-31E levee and the Turkey Point entrance road north of the Plant was trapped and became concentrated via evaporation during the dry season. This evaporative-sourced hypersaline groundwater was limited to the upper 7-10 ft of the aquifer can be seen in 2018 AEM survey layers 1-3. At the same time, at depths of 20-25 feet (AEM layers 4 and 5),

groundwater salinities were lower with chloride levels similar to or less than seawater. From 2018- 2023, this more-dense, naturally sourced hypersaline groundwater has migrated downward under a density gradient, from layers 1-3 to layers 4 and 5. In layers 4 and 5, this shallow hypersaline water is not connected to the main hypersaline plume just north of the CCS.

The AEM data do not show continuity of hypersalinity in the inundated area with the CCS-sourced hypersaline plume. As this area is tidally influenced and periodically producing hypersaline waters in the upper layers that migrate downward, it is expected that the measured hypersaline volumes by layer will continue to change cyclically.

4.5.2 Comparison of the 2018 and 2023 AEM Survey Results Results of the 2023 AEM survey indicate that the calculated volume of hypersaline water in the compliance area is 21% lower than the calculated 2018 volume estimate with reductions shown in layers 6-8 and 11-14 where the hypersalinity within the compliance area is predominantly CCS-sourced. While small in magnitude, volumetric increases since 2018 are shown in layers 4 and 5 in the northeast corner of the compliance area east of the L-31E levee due to non-CCS-sourced hypersaline water that formed from seawater encroachment into the coastal marsh areas during Hurricane Irma. In this area, the spatial extent of this evaporative hypersaline groundwater found in the shallow portion of the Biscayne aquifer waxes and wanes over time as the denser water sinks. While the coastal evaporative formation of hypersalinity occurs regionally along the Model Lands and south Florida peninsular margin, only a small area northeast of the FPL property falls within the compliance zone and is measured by the AEM surveys. While the extent of hypersalinity in the upper five layers of the aquifer is comparatively 4-32

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary small, there is no CCS sourced hypersalinity in these layers in the remaining portions of the compliance area.

There are several locations where individual voxels appear to change from hypersaline to saline or vice versa. These voxels can be used to measure the progress of the remediation system or identify locations of uncertainty. The vast majority voxel changes from 2018 to 2023 are from hypersaline to saline showing the progress of the remediation system. All of the voxels that changed within layers 1-7 switched from hypersaline conditions to saline conditions indicating that the remediation system has been successful in removing most of the hypersaline water from the shallower portions of the aquifer. Voxel changes from hypersaline to saline conditions are also observed in mid-portions of the aquifer in layers 8-13. In general, these voxels are located in the central and eastern portions of the compliance area and also often correspond with an eastward retraction of the 19,000 mg/L threshold contour lines in 2023.

Conversely, there were also locations within the mid-portions of the aquifer where voxels switched from saline to hypersaline conditions. These voxels generally occur in clusters that are located on the westward side of the hypersaline plume in layers 9-13 where chloride concentrations are estimated to be closer to the 19,000 mg/L threshold. The estimated chloride concentrations in these voxel clusters do not appear to correspond to chloride concentrations or trends measured in nearby monitoring wells (TPGW-4 and TPGW-5) where chloride levels are lower than the 19,000 mg/L threshold and trends are stable or decreasing. Therefore, the changes from saline to hypersaline in those voxel clusters are more likely indicative of estimation error and statistical uncertainty due to the difficult process of accurately measuring AEM resistivity and then translating those readings into chloride estimates. Maps showing the locations of voxels that change from hypersaline to saline or vice versa are presented in Appendix G.

There are also voxels within each model layer where the bias adjusted chloride concentrations are estimated as hypersaline one year, but the next year as non-hypersaline, then hypersaline again, and so on (high-switch or vacillating voxels). There are relatively few high-switch voxels present in the shallower layers (1-7) or the deepest layers (13-14) of the AEM resistivity model. Layers 8-11 contain the largest proportion of high-switch voxels. In layer 8, most of these voxels are located in the southern portion of the AOC. Layer 9 exhibits high-switch voxels in various parts of the AOC, but again there are many close to the western and southern flanks.

There are also several high-switch voxels in layers 10 and 11 scattered somewhat randomly but tend to be concentrated west of the most intense portions of the hypersaline plume, and, in layer 10, several high-switch voxels are present along the western flank of the AOC or where the estimated chloride concentration hovers close to the 19,000 mg/L compliance threshold. These high switch voxels can serve as an empirical indication of uncertainty in measuring plume volumes in the mid-layers and may explain the apparent expansion of hypersaline plume volumes within Layer 9. Maps showing the locations of high-switch voxels by layer are presented in Appendix K The following describes changes in the hypersaline plume by layer. Chloride isoconcentration maps showing the 19,000 mg/L threshold are presented in Figures 4.5-1 through 4.5-9, and table 4.5-1 presents year specific bias AEM derived chloride volume estimates for 2018 and 2023.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4.5.2.1 Layer 6 The AEM data indicates that a pocket of CCS-derived waters >19,000 mg/L remains just west of the L-31E canal that extends a short distance to the north of TPGW-2. AEM data from 2018 and 2023 show the biased adjusted hypersaline plume volume in the compliance area for this layer has been reduced by about half. From 2018 to 2023, the AEM data shows an eastward retraction of the 19,000 mg/L boundary in the southern third of the compliance area toward monitoring sites TPGW-2 and TPGW-17.

4.5.2.2 Layer 7 Layer 7 most closely represents the upper high flow zone in the Biscayne aquifer near the CCS.

This layer shows a 61.8% reduction in the volume of hypersaline water within the compliance area from 2018 to 2023. The AEM data shows an eastward retraction of the 19,000 mg/L boundary in the southern third of the compliance area toward monitoring sites TPGW-2 and TPGW-17.

4.5.2.3 Layer 8 From 2018 to 2023, the 19,000 mg/L contour in the southern third of the compliance area generally migrated eastward towards the L-31E canal. Since 2018, the 19,000 mg/L contour near TPGW-18 migrated slightly eastward towards the L-31E canal since 2018. There also are isolated areas of >19,000 mg/L estimated chloride south and southeast of TPGW-18, west of TPGW-12, and at TPGW-4. AEM data from 2018 and 2022 show the bias adjusted hypersaline volume in the compliance area for this layer has been reduced by 50.3%.

4.5.2.4 Layer 9 Overall, there is fairly continuous lens of hypersalinity located an area 1 to 2 miles west of TPGW-2 and TPGW-17 in both the 2018 and 2023 AEM surveys, and generally, there is little discernible change in the position of the 19,000 mg/L contour in that area between 2018 and 2023. There is some eastward movement of the 19,000 mg/L contour apparent near TPGW-2 and northward in 2023. A slight increase in hypersaline volume of 0.6% was observed from 2018 to 2023 in Layer 9.

Layer 9 contains a large proportion of high switch voxels. The high-switch voxels observed in Layer 9 tend occur in locations where the estimated chloride concentration hovers close to the 19,000 mg/L compliance threshold. Furthermore, chloride concentrations and salinity measured in the monitoring wells screened within or near layer 9 within and outside of the compliance area demonstrate decreasing or non-significant trends. Areas where chloride concentrations or salinity appear to be increasing are located outside and to the west of the compliance area, where chloride and salinity levels are substantially below their respective hypersalinity thresholds.

Lithologic, acoustic imaging, and seismic borehole logs for TPGW-2 and TPGW-4 (JLA 2010) and data described in Fish and Stewart (1991) (E-E geologic cross section) suggest that at least the upper part of layer 9 is a lower permeability sandstone or sandy limestone near the bottom of 4-34

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary the Ft. Thompson Formation. The drillers log for TPGW-22 shows extensive high-porosity silty materials. These clastic materials tend to be more conductive in nature due to the presence of naturally occurring clay minerals. Variations in formation lithology and porosity can affect AEM estimations of chloride concentrations with higher clay content and porosities resulting in elevated estimates of chlorinity. The area of apparent slightly hypersaline to slightly less than hypersaline aquifer pore waters located in the southwest corner of the AEM survey may be caused by the localized presence of clay minerals or variations in porosity.

4.5.2.5 Layer 10 Overall, the bias adjusted 19,000 mg/L contour line for Layer 10 remains relatively unchanged from 2018 and 2023, and chloride estimates indicate that the hypersaline plume has also remained relatively stable with 2% reduction of the hypersaline plume volume from 2018-2023.

It appears that there is an isolated area of hypersaline water between TPGW-5 and TPGW-18 that is separated by a hole of saline water. In this same area, there is a cluster of voxels that have shifted from saline to hypersaline, and several high switch voxels are also present in the area. Chloride concentrations and salinity measured in nearby monitoring well TPGW-5M that is screened within layer 10 are less than the hypersaline threshold and demonstrate decreasing or non-significant trends indicating that the hypersaline plume is not migrating westward. Future AEM evaluations will show whether this area persists, indicative of a high-porosity lithologic sequence, or dissipates as a result of RWS operations.

4.5.2.6 Layer 11 Layer 11 showed a 22% volumetric reduction of the hypersaline plume since 2018. It appears that the hypersaline plume in layer 11 has retracted eastward leaving a pocket of hypersaline water remaining around TPGW-5. Similar to Layer 10, there is a cluster of voxels in that area that shifted from saline to hypersaline, however, chloride concentrations measured near Layer 11 do not indicate the hypersaline plume is moving westward.

4.5.2.7 Layers 12 and 13 Layers 12 and 13 showed a 22.5% and 26% volumetric reduction of the hypersaline plume since 2018, respectively. The western extent of the 19,000 mg/L chloride retracted eastward indicating that the remediation is influencing in the lower portion of the aquifer and at significant distances west of the CCS. Similar to layers 10 and 11, there are clusters of voxels in the northwestern corner of the compliance area that switched from saline to hypersaline, and there are clusters of high switch voxels in the same general areas indicating that there is some uncertainty with regard to the estimated chloride concentrations in those locations.

4.5.2.8 Layer 14 The extent of the bias adjusted 19,000 mg/L contour in Layer 14 remained relatively stable from 2018 through 2023; however, eastward movement of the plume is apparent between TPGW-1 and TPGW-18 indicating that the remediation system is influencing groundwater flow in the deeper layers. Additionally, a pocket of hypersaline water observed in the northwestern corner 4-35

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary and on the northern edge of the compliance area disappeared in 2023. Overall, a 10% reduction of hypersaline plume volume was calculated for Layer 14.

Figure 4.5-1. Layer 6, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-36

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-2. Layer 7, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-37

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-3. Layer 8, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-38

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-4. Layer 9, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-39

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-5. Layer 10, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-40

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-6. Layer 11, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-41

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-7. Layer 12, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-42

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-8. Layer 13, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-43

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary Figure 4.5-9. Layer 14, 19,000 mg/L Chloride Concentration Contours for 2018 and 2023 4-44

FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary 4.5.3 Summary of 2023 AEM Survey Results In response to peer review comments and suggestions from MDC consultants, FPL has revisited the interpretative approaches used to relate AEM bulk resistivity to monitoring well chloride in order to map chloride distributions in coastal southeast Florida. The Year 5 results are different from previous plume reduction estimates while shown to be more mathematically robust, statistically more confident, and leading to plume estimates with less uncertainty (compared to analyses in previous years).

How to interpret the results is more complex because while the revised approach reduced uncertainty in some areas of the process, it exposed random yearly variation in resistivity data that was previous obscured. The effect of this annual variance is illustrated in the yearly percent change values on Table 4.5-1. The table shows a reasonable reduction in plume volume for remediation year 1 through 3 with the plume reduced by 29% in 2021. However, over the next two years the plume expanded to only a 21% reduction by 2023. These oscillating volume changes appear to be the result of voxels switching back and forth from hypersaline to non-hypersaline in areas far west of the CCS in isolated pockets that are laterally and vertically discontinuous from the CCS. The increases are not reflected in monitoring data or modeling results.

Table 4.5-1. Revised Estimates of Hypersaline Plume Volume Changes by Layer and Year AEM Layer Revised Percent Change in Hypersaline Plume Volume Year 2019 2020 2021 2022 2023 1 -100.0% -100.0% -100.0% -100.0% -100.0%

2 -34.1% -100.0% -100.0% -100.0% -100.0%

3 26.9% 11.2% -100.0% -51.5% -97.0%

4 147.8% 159.4% 50.7% 159.4% 156.5%

5 -66.8% 6.9% 13.8% 50.4% 32.3%

6 -36.3% -42.9% -43.2% -74.5% -50.7%

7 -13.4% -38.4% -59.3% -84.3% -61.8%

8 -10.3% -28.3% -57.7% -17.9% -50.3%

9 -13.1% 7.4% -13.2% 23.3% 0.6%

10 -0.4% 2.2% -8.3% -2.1% -2.3%

11 -15.8% -23.8% -33.9% -34.0% -22.0%

12 -15.6% -23.6% -32.4% -30.9% -22.5%

13 -7.4% -24.9% -32.2% -36.0% -26.0%

14 -2.6% -9.3% -15.9% -11.8% -10.3%

All Layers -11.0% -17.3% -28.9% -24.1% -20.8%

Negative percentages indicate plume volume reduction.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary However, despite the unexplained variability in the data, the higher confidence Year 5 evaluation indicates the plume has shown a statistically valid reduction ranging from 21 to 29% and has identified areas where strong and consistent reductions have occurred, as well as areas where more information is needed to explain the variability.

4.5.4 Factors for Additional Evaluation As described above, revised statistical methodology was used to normalize AEM resistivity data using Archies Law and produce bias adjusted chloride estimates using Deming regression that could be interpolated into the AEM resistivity model to evaluate changes to the hypersaline plume due to the remediation system. The resulting bias-adjusted chloride estimates account for underlying variability that was not previously considered in the chloride estimates for Years 1 through Year 4, and better represent changes in the hypersaline extent over time.

Year after year, great care is taken to monitor changes in chloride extent using AEM resistivity surveys. The remote AEM surveys are conducted to provide an accurate estimate of the spatial extent of hypersaline waters with minimal disturbance to the surrounding environment. Because AEMs continuous measurement of changes in bulk resistivity produces the most complete data-sourced expression of salinity dynamics available, FPL recommends the continued use of the AEM survey to monitor changes to the hypersaline plume. Moving forward, FPL also plans to conduct additional evaluations to determine whether better alignment between monitoring well data, groundwater model-based plume dynamics, and AEM results can be achieved.

FPL plans to evaluate the following in preparation for the Year 6 RAASR:

Changes in chloride concentrations that vacillate around the 19,000 mg/L threshold.

High switch (i.e., vacillating) voxels appear to serve as an empirical indication of uncertainty in measuring plume volumes in the mid-layers of the AEM model and may be an explanation of why the hypersaline plume appears to be expanding in Layer 9. A large portion of the high switch voxels or cluster voxels appear to correspond with chloride concentrations that hover around the 19,000 mg/L chloride threshold. The resolution of the AEM survey data is much better than initially anticipated; however, it remains difficult to see the changes in chloride concentration that hover around the 19,000 mg/L chloride threshold. Additional assessment is warranted to quantify hypersaline plume changes in locations where the chloride concentration hovers near the 19,000 mg/L threshold.

Areas where bias adjusted chloride concentrations and monitoring well chloride levels are not in agreement. In the areas where there is uncertainty, bias corrected chloride levels were compared to chloride concentration in nearby wells screened in corresponding AEM model layers. In all instances, the bias adjusted chloride levels were higher than what was observed in the nearby monitoring wells. FPL plans to evaluate the cause and the lateral extent of the differences to determine whether it is a localized condition or a large-scale factor.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 4. CSEM Survey Sum m ary

The addition of salinity to regression calculations. The evaluation of additional water quality data may shed light on some of the uncertainty that remains in estimating the changes in the extent of the hypersaline plume, and it may help to highlight nuances that are not apparent when solely converting AEM resistivity to chloride.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel 5 GROUNDWATER MODEL Data from the 2018 baseline and Years 1-5 remediation operations have been incorporated into and assessed in the Turkey Point variable density dependent solute transport model to provide a better understanding of the hydrogeology of the study area, improve the models ability as a predictive tool, and contribute to the assessment of the progress of remediation and predictions of future performance.

5.1 MODEL OVERVIEW AND EVOLUTION 5.1.1 Objectives The variable density flow and salt transport model developed for the design of the FPL Turkey Point Biscayne Aquifer RWS has been updated and recalibrated using data from the fifth year of RWS operation. This update represents the eighth version (V8) of the model. The objectives of the update and recalibration are to inform and reduce the uncertainty of the model and to improve the models simulation of saltwater conditions throughout the full aquifer vertical profile and the models capability to predict the plume response to the RWS. Revised Year 10 model predictions and milestones to evaluate the systems performance with respect to achieving the objectives of paragraph 17,b.ii., of the CA are provided in this section.

These objectives were addressed by the following actions:

1. Performance of a sensitivity analysis using the model (version 7 or V7) used in the prior 2022 RAASR to investigate potential causes of that models inability to align the saline-hypersaline interface (HSI) position along the base of the aquifer and retract the HSI in a manner consistent with monitor well and CSEM data.

2. Incorporation of the results of the sensitivity analysis into the V8 model calibration process.

3. Removal of hydraulic conductivity estimates of the RWS wells as starting values and calibration targets based on analysis that indicated this subset of data was statistically different than the hydraulic conductivities determined by more rigorous means in the TPGW wells.

4. Modification of the L-31E boundary condition north of S-20 from a river to a drain, allowing L-31E to only remove water from (rather than providing water to) the aquifer.

5. Incorporation of monthly water and salt fluxes between the CCS and groundwater calculated from the water and salt balance models (FPL 2023a) for the period September 2010 to May 2023, to better align the modeled calculated rates of groundwater-CCS water exchange with those derived from the calibrated CCS water and salt balance model.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel

6. Incorporation of the salinity, water level, and mass extraction data from the RWS and UIC test production wells collected during the fifth year of RWS operation.

7. Elimination of CSEM-based salinities as calibration targets because the 2023 and earlier revised values were not available at the time of commencement of the model calibration.

8. Increasing calibration target weights on overall salinity changes during remediation to further emphasize the accurate simulation of the movement of the HSI over the course of RWS operation.

9. The updated V8 model was then used to assess RWS impacts on the degree of CCS-sourced hypersaline groundwater plume retraction at Year 5 and update Year 10 plume retraction forecast milestones.

5.1.2 Model Versions The current groundwater flow and salt transport model documented in Appendix J is the eighth version (V8) of a 3D regional model developed by FPL to evaluate various projects associated with the Turkey Point CCS. The model has undergone an evolutionary process as the objectives of the modeling change, as progressively more data are added, and as the knowledge base expands. The evolution of the model to date is summarized in Table 5.1-1 and presented in detail in Appendix J.

FPL originally developed a 3D SEAWAT (Langevin et al. 2008) model wherein density varied as a function of both salinity and temperature (Tetra Tech 2016a). This model is referred to as the V1 model. The purpose of the V1 model was to evaluate alternatives for compliance with the MDC CA and FDEP CO that required stopping the westward migration of hypersaline water and retracting hypersaline water north and west of the CCS to the L-31E canal and the FPL property.

This model simulated the period from predevelopment (early 1940s) through 2015 and was calibrated by manual methods to measure water levels and salinity. The model was used to evaluate a number of potential groundwater remediation projects that resulted in the selection of Alternative 3D, which involved implementing a groundwater RWS consisting of 10 wells screened to the base of the Biscayne aquifer capable of pumping 15 mgd of hypersaline groundwater that would be disposed in an existing UIC DIW. Based on the V1 model (with minor modifications requested by MDC and the SFWMD) and the associated results related to the retraction of the hypersaline plume, the models application in the assessment of Alternative 3D were conditionally approved by MDC on September 29, 2016.

In addition to using the groundwater model to aid in the evaluation and selection of a groundwater remediation system, FDEP directed FPL to use the variable density 3D groundwater model developed under the MDC CA to allocate relative contributions of the CCS and other entities or factors on the movement of the saltwater interface. To conduct this evaluation, several modifications, including many of those required by MDC, were necessary and incorporated into what is referred to as the Version 2 (V2 model). The results of the V2 modeling were presented to FDEP on June 19, 2019.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel In compliance with paragraphs 17.b.ii., and 17.d.v., of the MDC CA, as amended on August 20, 2019, FPL has annually updated the variable density flow and salt transport model informed with data collected during operation of the RWS. In addition to inclusion of additional RWS pumping rates and mass extracted, TPGW well water levels and salinities, CCS stage and salinity, and CSEM salinity data, each version of the model was modified with new findings or modeling techniques and recalibrated. Examples of modifications include: 1) use of the automated parameter estimation technique (PEST); 2) incorporation of compatible elements of the surface water routing package developed by the USGS and implemented by Hughes and White (2014);

3) incorporation of geologic information obtained during and after installation of the RWS and TPGW monitoring wells; 4) use of an averaging procedure to create a smoother CSEM salinity distribution that contained less apparent outliers than the prior versions; 5) inclusion of layer-wide heterogeneity of porosity instead of the layer-wide homogeneity used in the prior models; and 6) increasing the vertical resolution of the model from 11 to 17 layers to better assess remediation progress in the lower portions of the Biscayne aquifer. Following calibration, the models were used to make projections regarding RWS performance over the remaining years of operation. In addition to the V2 model, six model updates have occurred annually such that the current model is referred to as the V8 model.

5.1.3 Sensitivity Analyses Conducted with the Version 7 Model Several of the recommendations in the Year 4 RAASR (FPL 2022b) and in the independent model review conducted by Groundwater Tek Inc on behalf of MDC RER (GTI 2023), sought to obtain a more accurate present-day location of the hypersaline interface as the V7 modeled plume appeared more extensive than suggested by the CSEM and monitoring well data. To investigate the causes of the models inconsistent alignment of both the HSI position along the base of the aquifer and the retraction of the HSI, sensitivity analyses were performed using the V7 model to identify potential changes to model parameters, boundary conditions, initial conditions, or calibration techniques that have the greatest influence on hypersaline plume location and retraction. A model sensitivity analysis involves a series of simulations where model inputs are varied from their calibrated values in a systematic manner to enable quantitative evaluation of effects of those variations on model outputs. The insights gained through the sensitivity analyses would be used to improve model responses and calibration of the V8 model.

Table 5.1-2 shows details of the sensitivity evaluations that were performed with the V7 model.

Four categories of evaluations were performed consisting of: 1) containment evaluation, 2) assessment of near-RWS hydraulic conductivities, 3) representation of the L-31E canal as a discharge boundary, and 4) representation of CCS flux based on the water and salt balance. Most of the evaluations involved multiple simulations to either represent both the historical and future aspects of the modeling or to obtain a true sense of sensitivity by various degrees of parameter perturbation. Others involved detailed analysis of water budgets and model parameter distribution.

Based on the results of the sensitivity simulations, updates associated with the formulation of the V8 model included the following items: 1) correcting the modeled depth of the open hole intervals for RWS wells -4, -5, -7, and -9; 2) removing the hydraulic conductivities values estimated from geological logs of the RWS wells from the derivation of initial, pre-calibration 5-3

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel hydraulic conductivity fields in each layer in the model; 3) representing the entire length of L-31E as a drain boundary condition; and 4) using fluxes derived from the CCS water and salt balance models to represent the CCS-aquifer hydraulic connection in the numerical model.

Additional details regarding the V7 model sensitivity analyses are presented in Appendix H.

5.1.4 Description of Version 8 Model Detailed descriptions of the V8 model assembly, calibration, and predictive simulations are included in Appendix J. The V8 model uses the same basic plan-view framework as the prior V1 though V7 models. It simulates a 276-square-mile area that is subdivided from west to east into 274 columns and from north to south into 295 rows. The width of the rows and columns vary between 200 ft and 500 ft, with smaller grid cell dimensions located near the CCS. The model domain overlain by the model grid is shown on Figure 5.1-1.

The layering and vertical framework of the V8 model is identical to the V7 model, with the Biscayne aquifer divided into 17 layers. The uppermost model layers (layers 1 through 4) represent the Miami Oolite. The thicker Fort Thompson Formation was divided into 13 layers (layers 5 through 17). Well borings and geophysical logs were analyzed to define geologic contact elevations containing zones with large, connected voids to determine the regional hydrostratigraphy. Consequently, three such high flow zones were represented in the regional model based on their relatively higher hydraulic conductivity. The upper high flow zone (layer 4) occurs at the base of the Miami Oolite; the middle high flow zone (traversing layers 7 through 11 across the model domain) is located in the approximate middle of the Fort Thompson formation; and the deep high flow zone (traversing model layers 11 through 17 across the model domain) is located near the base of the Fort Thompson Formation.

The 17-layer configuration of the V7 and V8 models was a refinement of the 11-layer configuration in the V1-V6 models. The V1-V6 layer structure was maintained for ease of results comparison of the V8 to prior models by subdividing the prior layers into even multiples.

As such, former layer 7 was subdivided into two layers (new layers 7 and 8); former layer 9 was subdivided into two layers (new layers 10 and 11); former layer 10 was subdivided into three layers (new layers 12, 13, and 14); and former layer 11 was subdivided into three layers (new layers 15, 16, and 17). Horizontal hydraulic conductivity estimates, based on geologic cores and geophysical logs collected from TPGW monitoring wells, were interpreted for each model layer by JLA Associates (2022). These values were kriged to form hydraulic conductivity arrays for each model layer. This methodology allowed the high-conductivity zones to be discontinuous or to be present in multiple layers. Figure 5.1-2 provides a cross-sectional view of the 17 layers of the V8 model and how they correspond to the hydrogeologic formations. The location of this cross-section, along row 116 of the model, is shown on Figure 5.1-1. The interpreted values were used as the starting values in the calibration with the opportunity for adjustment based on the ability of the model to replicate measured heads and concentrations.

The USGS groundwater flow and solute transport modeling tool SEAWAT Version 4 (Langevin et al. 2008) was used in this analysis and the prior V1-V7 modeling analyses. This SEAWAT version includes: 1) solute transport simulations through the integrated MT3DMS (IMT) Process (Zheng and Wang 1998); and 2) variable-density flow (VDF) simulation through the VDF 5-4

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel process. SEAWATs VDF package was used to simulate the density effects of both temperature and salinity. SEAWAT inputs and outputs are specified in terms of point-water heads (Langevin et al. 2008) that represent the hydraulic head at a given location based on salinity and temperature. SEAWAT solves the groundwater flow and transport equations after converting point-water heads to reference heads or equivalent freshwater head at the reference temperature.

The boundary conditions applied to the V8 model are similar to those applied in the prior models. Namely, specified head-boundary conditions are used to simulate the effects of temporal changes in Biscayne Bay and some canals on groundwater flow and transport. Sea-level rise is incorporated into the temporal Biscayne Bay changes based on historical data for the calibration period and a projected rate of 0.13 inch/year (USEPA, 2023). L-31E was changed to a drain boundary condition for its entire length based on sensitivity analysis (Section 4 of Appendix J) that indicated that the previously used river boundary condition supplied an unrealistic amount of water to the aquifer. The CCS is treated as a specified flux boundary condition using flux from the water and salt balance model for the period 2010-2023. The CCS was treated as a river boundary condition during the 1973-2010 period for which the water and salt balance could not provide data. General head boundaries are used to simulate the exchange of groundwater across the models lateral boundaries on all sides. NEXRAD-based rainfall rates and historical patterns (both spatial and temporal) in land use are used to estimate the amount of groundwater recharge throughout the model domain. Reference evapotranspiration (ETo) data and land use/land cover data are used similarly to estimate groundwater evapotranspiration (ET) rates as a function of groundwater head. Consumptive use of groundwater for agricultural purposes and industrial uses are simulated as specified withdrawals; and they were estimated based on land cover, estimated local rainfall/recharge, and ET rates. Municipal and other industrial groundwater uses are also simulated as specified withdrawals and are based on data as much as possible. The temperatures and salinities assigned to water entering from the various boundaries simulated are also based on actual data, as much as possible.

The V8 model incorporates canal hydraulics and groundwater interactions based on Hughes and Whites (2014) modeling for MDC that were added in the V2 model. Details of these additions are included in Appendix J.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel 5.2 MODEL MODIFICATIONS/CALIBRATION The model was calibrated to 84 years of data, including Years 1-5 of operation of the RWS. The resulting calibration indicates the model is a reasonable tool to be used in conjunction with monitoring data and CSEM results to assess progress in meeting the groundwater remediation objectives of the MDC CA and FDEP CO. Although the V8-modeled 2018 hypersaline/saline groundwater interface aligns better with data than prior models, continued improvements in the model's alignment with CSEM and monitoring well data at the edge of the hypersaline plume in 2018, prior to remediation and during subsequent remediation years, is needed to improve reliability of long-range remediation forecasts.

5.2.1 Model Calibration Process In order to perform reliable predictions and satisfactorily meet the objectives of this modeling effort, the SEAWAT model required calibration. Model calibration is the process of adjusting parameters and boundary conditions within reasonable ranges to match historical observations reasonably well. The ability to replicate past conditions in the calibration period provides confidence that the model can simulate future conditions in the model applications. The process for developing a model capable of providing accurate projections of RWS operation involves calibration of the model to prior measured data that are similar to those of the projections it is to make. This model calibration involved matching water level and salinity observations. The calibration period includes the V7 model calibration period (i.e., pre-development through May 2022) plus an additional 12 months. This 12-month period does not include the June 2023 CSEM dataset because it was not available at the time of calibration.

The calibration model is subdivided into four timeframes, each of which simulates the development and movement of the saltwater wedge under different hydrologic and anthropogenic stresses. These periods are defined as follows:

1. Pre-development steady-state flow model (prior to 1940)

2. Steady-state flow and transient transport calibration model (1940-1968)

3. Seasonal transient flow and transport calibration model (1968-2010)

4. Monthly transient flow and transport calibration model (2010-2023)

The final period includes the five years of RWS operation. Operational pumping rates for each RWS well are input monthly. All available precipitation and boundary condition data (i.e., canal stage) are also used. Model results for water levels, salinities at monitoring wells, and mass extracted by the RWS are compared to measured values.

Calibration was performed primarily using automated PEST, which seeks to minimize either the summation of weighted residuals or the differences between the sought, observed, and measured values and the interim calibrated values of targets by using a systematic mathematical optimization procedure. An additional manual calibration of deep aquifer vertical hydraulic 5-6

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel conductivities and CCS leakances was conducted to further improve the models simulation of TPGW salinities and the location of the 2018 hypersaline interface relative to prior models.

5.2.2 Model Calibration Results The calibration results for water levels and relative salinities are shown in Table 5.2-1. Seasonal and monthly transient model water levels and relative salinities are shown separately in Appendix J. In general, the monthly dataset is considered more reliable than the seasonal dataset because it uses the multi-depth and short-screened TPGW wells at which groundwater levels and salinity are measured on an hourly basis. As a result, the monthly dataset also has considerably more data despite its shorter duration (2010-2023). A robust assessment of model calibration quality and statistics is provided in Appendix J.

The model responds similarly to the actual hydrologic system during the first five years of RWS operation in that salinity changes are only observed in wells relatively close to the RWS (e.g.,

TPGW-1). Except TPGW-17, salinity changes in wells near the RWS are observed only in shallow and intermediate wells. Model versus measured changes in salinity since 2018 for the shallow and intermediate zones of wells TPGW-1, TPGW-2, TPGW-4, TPGW-15, TPGW-17, TPGW-18, TPGW-19, and TPGW-22 are shown on Figure 5.2-1. Comparison of the model to measured salinity changes is very good for these wells, but inexact. Where simulated changes in salinity notably deviate from observed changes (TPGW-1M, TPGW-15M, TPGW-18M), the model over-simulates salinity decline.

The model matches well to the measured total salt mass extracted by the RWS (Figure 5.2-2),

although there is some under-simulation in later time. The match for individual wells is also good (Figure 5.2-3), but mass extracted is under-simulated at RWS-4 and RWS-7 and over-simulated at RWS-10. During the first five years of RWS operation, measurements indicate that approximately 5.81 million tons of salt has been removed from the Biscayne aquifer by the RWS wells. The model calculates 4.71 million tons of salt removed by the RWS wells during this time frame. The salt mass removed from the aquifer contributed to a 46% reduction of hypersaline volume and 71% reduction in hypersaline mass within the compliance boundary between 2018-2023.

Based on the success in meeting the calibration goals, the sequence of calibration models was deemed satisfactory to employ in the execution of the predictive or forecast model.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel 5.3 REMEDIATION YEAR 10 FORECAST Predictive model runs indicate the RWS will retract hypersaline groundwater in the upper 70% of the Biscayne aquifer (layers 1-11) to the FPL property within 10 years of RWS operation. By 2028, the hypersaline plume volume is modeled to be reduced by 59% and the hypersaline plume mass by 80%

from their respective conditions in 2018.

5.3.1 Description of Remediation Simulations The projected results of RWS operation between years 6-10 were simulated in a similar fashion as occurred during years 1-5. The initial conditions for the simulation were the ending conditions (i.e., salinity, temperature, and water level) of the final period of the calibration simulation (June 2023). Climate conditions (e.g., precipitation, evaporation, canal stages) for the 2017-2018 period used in the calibration were repeated during the predictive period. This 1-year sequence is marked by precipitation that is below normal. NEXRAD-based annual precipitation on the CCS is 49.7 inches, which is a conservative prediction of westward movement of the hypersaline interface, whereas the average annual (June to May) precipitation from 2010 through 2023 measured at the Miami International Airport, approximately 25 miles north of Turkey Point, was 69.0 inches (NOAA, 2023). This methodology uses data and conditions that represent a recent time frame of varied hydrologic conditions and is a reasonable approximation of future conditions, albeit a conservative approximation based on the relatively low precipitation. The RWS was simulated to operate according to the design: 1.5 mgd discharging from each RWS well, totaling 15 mgd withdrawal. The CCS was set at a salinity of 34 PSU for the duration of the predictive period. In addition, the UIC test production wells were set to withdraw a total of 3 mgd from beneath the CCS for the duration of the remediation period.

5.3.2 Remediation Forecast Model simulation of the position of the HSI in Years 5 and 10 of remediation were determined using the V8 model. Year 5 was included in the historical model, and Year 10 estimates are produced by a predictive model. Retraction to the L-31E canal is generally achieved in the upper 11 model layers (approximately 70% of the Biscayne aquifer thickness) by year 10 of remediation. By 2028, the hypersaline plume volume is modeled to be reduced by 59% and the hypersaline plume mass by 80% from their respective conditions in 2018. Figures 5.3-1a, 1b, and 1c illustrate the Year 5 (2023) and Year 10 (2028) plume retraction at shallow, intermediate, and deep aquifer horizons. To the west of the CCS, the plume is retracted in model layers 12-14, albeit not to the L-31E canal. In layers 15-17, the plume is retracted along the northern portion of the HSI. Due west of the southern portion of the CCS, however, the plume is shown to expand slightly further west through Year 5 and retracted back to the 2018 (start of RWS) interface location by Year 10.

In addition, there appears to be contribution from non-CCS, coastal, evaporative-formed hypersaline groundwater that is recharging the hypersaline plume north and south of the CCS.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel The V8 and earlier versions of the model have shown this process to be simulated with the surface-formed hypersalinity migrating vertically in the aquifer and recharging the lower model layers. Retraction in southern areas surrounding the CCS could be hampered by continued addition of non-CCS sourced hypersaline water from the south. Additional evaluation of the models representation and extent of this process should be evaluated to determine the degree to which this source of hypersalinity could impact the assessment of CCS remediation progress.

Particle tracking conducted using the V8 model (Figure 5.3-2), confirmed hypersaline water from the CCS is intercepted, captured, and contained beneath the CCS and no longer migrates into the compliance zone. This analysis was conducted for all model layers from initiation of the RWS operations through 10 years of remediation. These figures are generated by initializing particles in cells surrounding the RWS wells (in the areas within the red outline in Figure 5.3-2) uniformly for all layers and highlighting the starting locations of each particle that ends at the RWS in orange.

Figure 5.3-2 illustrates that the RWS prevents water from the CCS from flowing through and westward past the RWS. This includes the deep layer where further analysis revealed that the apparent gaps between RWS-4 and RWS-5 (and to a smaller extent between RWS-5 and RWS-6) are areas where groundwater flows toward RWS wells, but it does so at a slower rate along longer and more circuitous paths. As a result, this groundwater is not captured by an RWS well within the 10-year timeframe, although eventual capture appears conclusive.

This evaluation indicates RWS operation provides a hydraulic constraint to the migration of hypersaline groundwater from beneath the CCS that halted westward migration of CCS-sourced hypersaline groundwater shortly after RWS operations began. This constraint will be maintained through Year 10. Figure 5.3-2 shows the predicted capture zones of layers 4, 9, and 16; particle tracking for additional layers is shown in Appendix H. There is an extensive capture zone to the east and west in shallow/intermediate high flow zones (layers 4 and 9) despite these layers not being pumped. In contrast, capture zones with comparatively smaller radii surround each of the RWS wells in layer 16 (from which the RWS extraction occurs) indicate these wells obtain a smaller portion of their water laterally within those layers and more vertically from shallower overlying high flow layers. Said another way, comparatively larger portions of the water withdrawn from the recovery wells are provided vertically than horizontally in the model.

5.3.3 Model Recommendations Five recommendations for future evaluations of RWS performance are offered:

1. Refine the technique for using inputs from the water and salt balance in the groundwater flow and saltwater transport model with the goal of providing a better match to RWS mass extraction and salinity response to RWS pumping in nearby TPGW wells.

2. Continue to explore alternative conceptual models of the near-RWS flow system to align the modeled HSI more closely with those characterized by CSEM and monitor well data.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel

3. CCS salinities and climate conditions should continue to be monitored and the model updated and recalibrated with more data reflective of longer RWS operations. The longer period of RWS operation and consequent changes to salinities over a progressively larger area will help inform the model and increase its accuracy in simulating the effect of the RWS and forecasting longer-term performance.

4. Evaluations should be conducted to verify the degree to which model-generated, non-CCS hypersaline groundwater impacts remediation objectives.

5. Use the groundwater model to assist in the siting of any new monitoring wells.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Table 5.1-1. Summary of Groundwater Model Versions.

Calibration Hydraulic Conductivity Recharge CSEM Version Date Purpose Predictions Primary Change / Focus Method Representation Formulation Representation V1 June Design Manual Uniform within Net No 10-year Assess alternatives for 2016 RWS layers forward compliance; selected alternative 3D V2 June FDEP Automate Heterogeneous in Precipitation and Yes 40-year Differentiate between 2018 attribution d (PEST) layers 4,8,9,10,11 Evapotranspiration backward Recharge and ET; detailed analysis surface water representation; CSEM targets evaluate causal factors of regional saltwater intrusion V3 Oct. Year 1 Automate Heterogeneous in Precipitation and Yes 10-year 2nd round of CSEM and 2019 verification d (PEST) layers 4,8,9,10,11 Evapotranspiration forward recent TPGW & RWS wells of RWS as targets; verify with stress (RWS).

V4 Sept. Year 1 Automate Heterogeneous in Precipitation and Yes 9-year Recent TPGW & RWS wells 2020 Calibration d (PEST) layers 4,8,9,10,11 Evapotranspiration forward as targets; incorporation of to RWS geologic information at TPGW and RWS locations V5 April Year 2 Automate Heterogeneous in Precipitation and 1000 x 1000 ft 8-year 3rd round of CSEM and 2021 Calibration d (PEST) layers 4,8,9,10,11 Evapotranspiration targets based on forward recent TPGW & RWS wells to RWS averaging of as targets; revision to CSEM CSEM voxels targets to eliminate localized significant changes in salinity V6 Sept. Year 3 Automate Heterogeneous in Precipitation and 1000 x 1000 ft 7-year 4th round of CSEM and recent 2021 Calibration d (PEST) layers 4,8,9,10,11. Evapotranspiration targets based on forward TPGW & RWS wells as to RWS Contrast between 5,6, averaging of targets; porosity as a spatially and 7; 9,10, and 11 CSEM voxels variable parameter; sensitivity based on JLA analysis to guide calibration 5-11

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Calibration Hydraulic Conductivity Recharge CSEM Version Date Purpose Predictions Primary Change / Focus Method Representation Formulation Representation V7 Oct. Year 4 Automate Heterogeneous in Precipitation and 1000 x 1000 ft 6-year 5th round of CSEM and recent 2022 Calibration d (PEST) layers 4 and 7-17. Evapotranspiration targets based on forward TPGW and RWS wells as to RWS Contrast between 7 averaging of targets; subdivision of and 8; 10 and 11; 12, CSEM voxels lowermost layers and 13, and 14; 15,16, inclusion of a lower high flow and 17 based on JLA zone; initial hydraulic conductivity from JLA; use of water/salt balance to determine CCS leaks V8 Oct. Year 5 Automate Heterogeneous in Precipitation and As calibration 5-year L-31E modified to only serve 2023 Calibration d (PEST) layers 4 and 7-17. Evapotranspiration target for 2018 forward as a drain; water and salt to RWS followed Contrast between 7 saline balance fluxes were used by manual and 8; 10 and 11; 12, /hypersaline directly to represent 2010 to adjustmen 13, and 14; 15,16, interface 2023 mass flux; removed K t of Kv and 17 based on JLA. estimated from geological RWS logs not used in logs of RWS wells.

interpolation.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Table 5.1-2. Description of Sensitivity Evaluations and Simulations Performed with the V7 Model.

Evaluation Sensitivity Description Question to be Answered Why Important?

No.

1 Assessment of RWS capture Does backward particle Containment is an objective of zones tracking provide additional CA insight to confirm capture/containment east of L-31E?

2 Assessment of Near-RWS Is the near-RWS hydraulic Hydraulic conductivity values Hydraulic Conductivities conductivity field, derived influence containment, from geological logs accurate? interface location, and retraction 3 Representation of the L-31E Is L-31E acting as a source of Accurate representation of the as a Discharge Boundary water to the RWS and causing RWS is key to evaluation of containment /retraction to be remedial actions under-represented?

4 Representation of CCS Flux Should fluxes from the water Accurate representation of the Based on Water and Salt and salt balance be used CCS is key to initial location Balance. directly to represent the CCS of hypersaline interface and in the numerical model? evaluation of remedial actions.

5 Representation of CCS Flux How should the period prior to Accurate representation of the prior to Water and Salt the simulation period of the CCS is key to initial location Balance data. water and salt balance be of hypersaline interface and represented in the numerical evaluation of remedial actions.

model?

Table 5.2-1. Calibration Statistic Summary for the Version 8 Model.

Model Target Type Units ME MAE RMSE MAE ÷ Range Seasonal Hydraulic Head ft -0.133 0.449 0.588 6.5%

(1968-2010) Relative Salinity R.S. 0.024 0.084 0.157 5.0%

Monthly Hydraulic Head ft -0.194 0.327 0.445 4.2%

(2010-2023) Relative Salinity R.S. 0.038 0.162 0.220 8.5%

Note: One Relative Salinity (R.S.) Unit = 35 PSU = 19,400 mg/L Cl 5-13

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Figure 5.1-1. Model Study Area Overlain by the Active Model Grid; Red Dashed Line Represents the Location of the Model Cross Section Shown in Figure 5.1-2.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Figure 5.1-2. Model Cross Section Showing Model Layering and Hydrogeologic Formations (Location of Cross Section Shown in Figure 5.1-1).

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel 1

Measured TPGW-1S 1 Measured TPGW-1M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 1

Measured TPGW-2S 1 Measured TPGW-2M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 1

Measured TPGW-4S 1 Measured TPGW-4M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 1

Measured TPGW-15S 1 Measured TPGW-15M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 5.2-1. Comparison of Model and Observed Changes in Relative Salinity with Time by Well Between April 2018 and May 2023.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel 1

Measured TPGW-17S 1 Measured TPGW-17M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 1

Measured TPGW-18S 1 Measured TPGW-18M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 1

Measured TPGW-19S 1 Measured TPGW-19M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 1

Measured TPGW-22S 1 Measured TPGW-22M Relative Salinity Change Relative Salinity Change Modeled Modeled 0.5 0.5 0 0

-0.5 -0.5

-1 -1 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 Apr-18 Oct-18 Apr-19 Oct-19 Apr-20 Oct-20 Apr-21 Oct-21 Apr-22 Oct-22 Apr-23 5.2-1 (continued). Comparison of Model and Observed Changes in Relative Salinity with Time by Well Between April 2018 and May 2023.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Salt Removed Per Month (Millions of Pounds) 220 200 Salt Removed (lbs x 10E+06) 180 160 140 120 100 80 60 Published (Data-Based) Estimate 40 20 v8 BPA1 0

May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 Date Figure 5.2-2. Comparison of Model and Observed Total Mass Extracted by the RWS Between May 2018 and May 2023.

5-18

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel RWS-1 (Million Pounds per Month) RWS-6 (Million Pounds per Month) 25 25 Published (Data-Based) Estimate Salt Removed (lbs x 10E+06) Salt Removed (lbs x 10E+06) 20 v8 BPA1 20 15 15 10 10 Published (Data-Based) Estimate 5 5 v8 BPA1 0 0 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 Date Date RWS-2 (Million Pounds per Month) RWS-7 (Million Pounds per Month) 25 25 Salt Removed (lbs x 10E+06) Salt Removed (lbs x 10E+06) 20 20 15 15 10 10 Published (Data-Based) Estimate Published (Data-Based) Estimate 5 5 v8 BPA1 v8 BPA1 0 0 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 Date Date RWS-3 (Million Pounds per Month) RWS-8 (Million Pounds per Month) 25 25 Salt Removed (lbs x 10E+06) Salt Removed (lbs x 10E+06) 20 20 15 15 10 10 Published (Data-Based) Estimate Published (Data-Based) Estimate 5 5 v8 BPA1 v8 BPA1 0 0 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 Date Date RWS-4 (Million Pounds per Month) RWS-9 (Million Pounds per Month) 25 25 Salt Removed (lbs x 10E+06) Salt Removed (lbs x 10E+06) 20 20 15 15 10 10 5 Published (Data-Based) Estimate 5 Published (Data-Based) Estimate v8 BPA1 v8 BPA1 0 0 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 Date Date RWS-5 (Million Pounds per Month) RWS-10 (Million Pounds per Month) 25 25 Salt Removed (lbs x 10E+06) Salt Removed (lbs x 10E+06) 20 20 15 15 10 10 Published (Data-Based) Estimate Published (Data-Based) Estimate 5 5 v8 BPA1 v8 BPA1 0 0 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 May-18 Nov-18 May-19 Nov-19 May-20 Nov-20 May-21 Nov-21 May-22 Nov-22 May-23 Date Date Figure 5.2-3. Comparison of Model and Observed Mass Extracted by Well Between May 2018 and May 2023.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Location Figure 5.3-1a. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 4.

5-20

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Location Figure 5.3-1b. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 9.

5-21

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Location Figure 5.3-1c. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 13.

5-22

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Location Figure 5.3-1d. Location of Initial, Year 5, and Year 10 Hypersaline Interface in Model Layer 16.

5-23

FPL Turkey Point RAASR Year 5 N ovem ber 2023 5. Groundw ater M odel Recovery Well System (RWS) wells RWS-captured particles Area within which particles were initiated Figure 5.3-2. Predicted Ten-Year Capture Zones for Model Layers (From Top Left to Bottom Left) 2, 4, 6 and (From Top Right to Bottom Right) 10, 13, 16.

5-24

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent 6 COOLING CANAL SYSTEM MANAGEMENT The average annual CCS salinity of 34 PSU was first achieved on September 23, 2022, and has been sustained since then through the time this report was written (over 400 days). The average annual CCS thermal efficiency of 85% from June 2022 through May 2023 is a 15% improvement over the minimum target value of 70%. Total nitrogen, total phosphorus, algae, and chlorophyll-a concentrations are declining, while light penetration and dissolved oxygen levels are increasing. This indicates significant improvements in CCS water quality. Commensurate with these improvements, crocodile nests and hatchlings have been at or near record highs for the past three years.

FPL has implemented multiple measures to improve conditions in the CCS, which are directly or indirectly linked to the remediation of the hypersaline groundwater plume. These management activities have been focused on reducing salinity and nutrients in the CCS and enhancing thermal efficiency for ensuring a long-term sustainable operation. Objectives, approaches, and targets for managing nutrients are described in the Turkey Point Cooling Canal System Nutrient Management Plan (NMP; FPL 2016b) and for thermal efficiency, in the Turkey Point Cooling Canal System Thermal Efficiency Plan (TEP; FPL 2016c).

6.1 COOLING CANAL SYSTEM SALINITY MANAGEMENT Paragraph 20.a. of the CO requires FPL to achieve a CCS average annual salinity at or below 34 PSU two out of every three years. Declines in CCS salinity are important as they correspond with reductions in the specific gravity of the CCS waters, thereby minimizing the driving head of the canal water, which reduces and ultimately halts seepage of hypersaline canal water into the underlying aquifer, thereby eliminating the source of hypersaline recharge to the aquifer and improving groundwater plume remediation west of the CCS.

One tool FPL uses to manage salinity within the CCS is to replace freshwater lost to evaporation with relatively low salinity brackish UFA water. Freshening is authorized by the Turkey Point site certification license (PA 03-45). In October 2021, FPL received a modification to the site certification to increase its freshening allocation to 10,950 million gallons per year (30 mgd) with monthly total withdrawals not to exceed 1,033.6 million gallons (34 mgd).

Using the modified UFA allocation, as needed, in combination with rainfall, an average annual salinity of 34 PSU was first achieved for the CCS (calculated as prescribed in Paragraph 29.j., of the CO) from September 24, 2021, through September 23, 2022. Since September 23, 2022, and for the following 403 consecutive days ending on October 31, 2023 (when this report was written), the rolling annual average CCS salinity had remained below 34 PSU, with the lowest average annual value of 32.8 PSU recorded from June 1, 2022, through May 31, 2023. The average annual salinity in the CCS has dropped 60% from a pre-freshening high of 82.5 PSU in 6-1

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent the 2014/2015 reporting period. Salinity reductions were achieved by above-average rainfall and by adding UFA freshening water during the reporting period.

This extended period of sub-hypersaline conditions in the CCS coupled with the operations of the RWS and UIC test production wells resulted in significant salinity declines beneath the CCS as shown by monitoring well TPGW-13S, located near the center of the CCS. Figure 6.1-1 shows modest reductions in groundwater salinity at TPGW-13S from December 2017 until September 2022 when the rolling annual average CCS surface water salinity first dropped to 34 PSU and below. The rate of salinity decline at TPGW-13S has increased significantly since late 2022 through September 2023, commensurate with the sustained elimination of CCS-generated hypersaline recharge.

Figure 6.1-1. TPGW-13S Quarterly Salinity Trends Figure 6.1-2 shows a time series of average salinity in the CCS (all stations) from July 2015, just prior to the start of FPLs CO-directed CCS freshening efforts, through September 2023.

Freshening actions during this period included short-term use of marine groundwater (intermittently from July 2015 to August 2017) and fresh surface water from the L-31E canal (intermittently from August through November 2015) but evolved to the strategic use of brackish UFA groundwater to offset evaporative losses and help conserve water resources. Based on the regression line, the figure shows a declining trend in salinity of approximately 30 PSU over the past eight years.

6-2

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent Figure 6.1-2. Declining Trend in CCS Salinity Over Time 6.2 COOLING CANAL SYSTEM NUTRIENT MANAGEMENT PLAN Total nitrogen (TN) and total phosphorus (TP) in the CCS have been clearly declining since June 2022. TN since mid-June 2023 is now ranging between 2.8-4.0 mg/L, approaching levels observed in 2010/2011. Most of the recent biweekly TP values (from mid-June to September 2023) are below 10 parts per billion (ppb), consistent with values observed in the healthy Everglades.

Paragraph 20.a., of the CO required FPL to submit a detailed report outlining the potential sources of the nutrients found in the CCS and included a plan for minimizing nutrient levels in the CCS. FPL submitted the plan for FDEP approval in September 2016 and began implementing the approved plan in July 2017, although several actions to improve CCS nutrient levels preceded the plan. The NMP includes both short-term actions and long-term objectives.

Short-term actions include nutrient and algae reduction, CCS sediment and vegetative management, and CCS salinity reduction. Long-term objectives of the plan focus on re-establishing seagrass meadows to stabilize nutrient levels over the operational life of the CCS.

The plan includes acceptable and good targets for achieving the plan objectives. These targets are specific to TP (<0.035 and <0.02 mg/L, respectively), TN (<5.0 and <2.5 mg/L, respectively), water clarity (between 2 and 10 ft to >10 ft, respectively), and salinity (40-50 PSU and <40 PSU, respectively). The plan identifies that achieving the target levels will reduce the severity and persistence of algae blooms and provide the environmental conditions necessary to support re-establishment of submerged aquatic vegetation in the system.

Nutrient management activities conducted during the reporting period included continued removal of non-native Australian pine (Casuarina equisetifolia) from the internal canal berms and along the perimeter berms, as they impede airflow and are a significant source of biomass entering the canals. The trees are either girdled, spiked with herbicide and left in place to die, or 6-3

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent completely felled and burned in place, with the stumps treated with herbicide. Since 2018, removal of Australian pines has occurred on more than 1,800 acres across the CCS and is an ongoing annual management activity.

Along with active removal of Australian pines, FPL has planted native grasses on berms to aid erosion control and improve berm stability. To date, approximately 448,000 units of native, salt-tolerant grasses have been planted on 10 berms and shorelines across the CCS; these plantings have been successful and are naturally expanding. Periodic control burns, when conditions warrant, help to control regrowth of Australian pines while sustaining grasses and native vegetation on the berms. In addition to grasses on the berms, the NMP includes reestablishment of native seagrasses within the canals. Seagrasses planted within the CCS at 24 sites from 2018-2021 have also been successful, with several sites established and expanding.

While not a component of the NMP, RWS operations have also minimized the inflow of groundwater-sourced nutrients to the CCS from the western face and bottom seepage and have captured groundwater nutrients from below, west, and north of the CCS. Approximately 210,000 lbs of TN and 2,600 lbs of TP were removed from the aquifer in Year 5. Since the start of RWS operations, nearly 970,000 lbs of TN and 13,000 lbs of TP have been removed from the aquifer.

Biweekly TN and TP data collected at CCS monitoring stations TPSWCCS-1 and TPWCCS-6 from April 2019 through September 2023 are shown on Figure 6.2-1. These data show a significant decline in TN, with average values since late August 2022 being below 5 mg/L, which is in the acceptable range per the CCS NMP; TN since mid-June 2023 ranges between 2.8-4.0 mg/L, approaching levels observed in 2010/2011. TP has fluctuated during this 4.5-year period, but it exhibits an overall declining trend. Almost 100% of the TP concentration from June 2022 through September 2023 were in the acceptable range, and over 45% of the TP values were in the good range. More notable is that most of the recent biweekly TP values (from mid-June to September 2023) are below 10 ppb. For context, 10 ppb is a very low level of TP and represents the healthy target for the Greater Everglades (EPA 2007). The CCS is a phosphorus-limited system; therefore, any bio-available phosphorus is scavenged, incorporated by living organisms, and rapidly recycled within the system when it is available.

Figure 6.2-1. CCS Average TN and TP Concentrations 6-4

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent Nutrients within the CCS are primarily bound within the algal community. The retention of TN and TP within the CCS water column for many years was likely a function of the rapid turnover and uptake of the algae within the system, which was often in excess of 1,000,000 cells per milliliter (mL). Increases in the rate of reductions in TN since June 2021 appear coincident with declines in algae as nitrogen levels approached and then dropped below the acceptable NMP target level of 5 mg/L. Further discussion of algal trends is found in Section 6.4.

6.3 COOLING CANAL SYSTEM THERMAL EFFICIENCY PLAN Paragraph 20.b., of the CO required FPL to submit a TEP that includes a detailed description of actions for the CCS to achieve a minimum of 70% thermal efficiency. The FDEP required plan has been implemented since July 2017, although several actions to improve CCS thermal efficiency preceded the plan.

During the 2022-2023 Annual Monitoring Report period, TEP activities focused on removing accumulated sediment in Section 1 and 2 canals and removing large invasive Australian pine (Casuarina equisetifolia) trees on the CCS berms that added organic nutrients to the canals and impeded air flow across the canals, which can negatively impact cooling. Based on the resulting data, flow adjustments on the canals continue to balance cooling across each section of the CCS and maintain high cooling efficiency of the overall system.

Implementation of the TEP has not only improved the amount of heat released from the canals as water travels from the plant discharge point to the intake location (an average of 9.2 degrees Celsius [ºC] or 16.2 degrees Fahrenheit [ºF] during the Annual Monitoring Reporting period from June 2022 through May 2023), but it has also maintained cooler water temperatures. Over the past six years, the annual average CCS water temperature has been 2.0°C (3.6°F) to 2.9°C (5.2°F) cooler than the peak temperatures observed in 2014-2015. CCS thermal efficiencies have significantly exceeded the CO minimum value (70%) since 2016, with the annual average CCS thermal efficiency for the period from June 2022 through May 2023 being 85% (FPL 2023a).

6.4 COOLING CANAL SYSTEM BIOTIC RESPONSES Salinity, nutrient, and thermal management actions appear to be driving the CCS ecosystem towards a new equilibrium, which is currently characterized by lower algal densities, lower particulate nutrient loads, improved water clarity, and coincident increases in biodiversity.

Implementation of FPLs nutrient, thermal efficiency, and salinity management plans have resulted in gradual sustained improvements in water quality. As a result, positive ecological developments are occurring. The NMP identifies salinity, water clarity, TN, and TP levels that, if achieved and sustained, would likely reduce blue-green algae, support re-establishment of 6-5

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent native seagrasses to moderate nutrients, and return the CCS to its original status as a thermally efficient, ecologically sustainable industrial cooling system.

To monitor progress in working toward these goals, FPL has collected algal data at TPSWCCS-1 to improve the understanding of algal dynamics in the CCS and assess potential impacts to operations of the plant. Algal counts from April 2019 through September 2023 are shown on Figure 6.4-1, along with related water quality parameters, including turbidity, chlorophyll-a, and Secchi disk depth, with linear trend lines for the 4-year, 5-month data period. Beginning around June 2021, there has been an increasing rate of decline in algal counts, biomass, turbidity, chlorophyll-a, and nitrogen and an increase in light penetration. Starting in June 2023, there was an even greater change with the lowest or near lowest algal counts, biomass, turbidity, and chlorophyll-a, and the highest light penetration recorded since biweekly data began being collected in April 2019.

In addition, dissolved oxygen (DO) is measured quarterly at seven monitoring stations in the CCS. In the first year of monitoring (2010-2011), the average annual DO was 5.39 mg/L.

However, in the 2014-2015 time frame, the average annual DO dropped to 2.53 mg/L. In subsequent years with implementation of various CCS management activities, DO began to trend upward (Figure 6.4-2), with average DO values around 5 mg/L from September 2020 through September 2023.

FPL has taken actions to improve DO levels in the CCS. Lower DO levels occur at the intake and discharge sides of the plant due to inflow of anoxic groundwater associated with canal drawdowns from the circulation pumps. As a result, aerators were added in discharge canals beginning in 2016. In addition, reducing orifice plates and upturned spray assemblies are placed on the UFA freshening wells 2-7 to highly aerate freshening discharges into the CCS. These actions, along with changes in algae levels and lower nutrient levels, likely play a role in the increased DO levels of the CCS.

Continued efforts by FPL have resulted in CCS waters approaching the ambient salinity levels characteristic of Biscayne Bay (Figure 6.1-2). Reductions in salinity and TN appear to be driving the CCS ecosystem toward a new equilibrium that may be characterized by lower algal densities, lower particulate nutrient loads, improved water clarity, and coincident increases in biodiversity. The stability in lower salinity over the last two years, coupled with the range of nutrient management efforts, have likely contributed to this decline in algal biomass. This reduction of algae biomass has resulted in concomitant improvements of water clarity within the CCS as observed by turbidity and Secchi disk readings (Figure 6.4-1).

Despite the decrease in algal concentrations within the CCS water column, chlorophyll-a concentrations from April 2019 through August 2021, while fluctuating, showed no trends.

However, since September 2021, there has been a clear decreasing trend in chlorophyll-a concentrations that parallels the decline in algae concentrations.

6-6

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent Figure 6.4-1. Time Series of (A) CCS Algae Concentrations, (B) Turbidity, (C) Secchi Disk and (D) Chlorophyll-a Concentrations Figure 6.4-2 Average Quarterly CCS Dissolved Oxygen: June 2015 through September 2023 As discussed in prior RAASRs, FPL began test planting the native seagrass Ruppia maritima in 2018, when CCS salinity levels were declining, to assesses viability under the CCS water conditions at that time. As documented in the NMP, reintroduction of this seagrass species is recommended for nutrient management. This species once occupied large areas of the CCS bottom, so reintroducing this species is preferred for initiating the shift within the CCS from an algal-based system to a more ecologically stable seagrass system. Seagrasses sequester nutrients within their biomass and also help maintain the stability of CCS sediments by capturing loose flocculent material within the bottom of the canal. Additionally, the nutrient turnover within a 6-7

FPL Turkey Point RAASR Year 5 N ovem ber 2023 6. Cooling Canal System M anagem ent seagrass system is much slower when compared to an algal-dominated system, resulting in more consistent and manageable nutrient levels and water quality. Many of the seagrass sites planted during 2018-2021 have successfully established; and although these patches are currently small (estimated to be 100 to 3,500 square ft), they are self-propagating and expanding. As water clarity improves, these grasses will likely be able to expand geographically and into deeper CCS waters, thereby reducing turbidity and further accelerating improvements to water clarity.

Commensurate with the thermal efficiency, salinity, and water quality improvements, there are also preliminary indications of improved habitat quality for various organisms within the CCS, resulting in increased non-algal biomass and biodiversity. During periods when CCS salinities were very hypersaline, fewif anyaquatic or benthic species were noted based on anecdotal observations. More recently, invertebrates such as polychaete worms, amphipods, anemones, tube worms, pistol shrimp, horseshoe crabs, and blue crabs have been observed within the canal itself, while mollusks, land crabs, and fiddler crabs have been sporadically observed along canal banks. Although fish densities are still low, there has been an increase in the number of fish species observed in the CCS since 2016. The system has become more diverse, changing from a system primarily dominated by sheepshead minnows to a wider range of fish species, such as gold spotted killifish, sailfin mollies, gobies, toadfish, barracuda, snook, and tarpon.

These observations of increased biological diversity within the canals are commensurate with salinity and nutrient management efforts, which have resulted in consistently lower salinity, nitrogen, and algae concentrations, and appears to have increased the diversity and food web complexity within the CCS. For example, a record number of crocodile hatchlings (565) were recorded in 2021; in 2022, there was a record number of nests on-site (33) with 512 crocodile hatchlings tagged; in 2023, the third highest number of crocodile hatchlings (483) were captured from 25 nests, all indicating successful nesting seasons. This success is attributable to FPLs habitat improvement measures as part of its continued commitment to improving and protecting ideal crocodile habitat. In addition to crocodiles, the CCS supports a wide population of wading birds.

Continued implementation of the NMP, TEP, and salinity management initiatives within the CCS have resulted in water conditions that have trended towards and achieved targets identified in the NMP that are considered favorable for reducing the dominance of algae in the CCS and are more conducive to seagrass re-establishment. However, the CCS is a large and complex system, and the biological responses are often driven by a number of interacting local, regional, and meteorological factors. FPL will continue to monitor CCS water quality and biologic responses resulting from the implementation of the cooling canal management plans and make adjustments as needed to maintain a sustainable cooling system.

6-8

FPL Turkey Point RAASR Year 5 N ovem ber 2023 7. Sum m ary and Recom m endations 7

SUMMARY

AND RECOMMENDATIONS 7.1 OVERALL

SUMMARY

Analyses of data collected through Year 5 of remediation document RWS operations are 1) halting the net westward migration of hypersaline groundwater; 2) intercepting, capturing, and containing hypersaline groundwater beneath the CCS, and 3) reducing the volumetric extent and salt mass of hypersaline groundwater west and north of FPL property. Salinity management actions have reduced the average annual salinity of the CCS to below 34 PSU since September 2022, eliminating the CCS as a source of hypersaline groundwater recharge. Remediation progress is exceeding the 2016 forecasted performance of the approved RWS; however, there is opportunity for system improvement. Recommendations for continued and enhanced RWS operations, monitoring, and reporting are proposed for agency review and approval covering remediation actions over the next 5 years leading up to the Year 10 review.

FPL submits this Year 5 RAASR, which covers RWS operations and groundwater monitoring data from July 1, 2022, to June 30, 2023, in compliance with the monitoring and reporting requirements of the MDC CA and the FDEP CO. In some instances, analytical data through September 2023 were incorporated to provide the most updated trends. This report incorporates the Year 5 RWS operational summary, groundwater monitoring well data and analysis, CSEM results based on the May 2023 survey, the updated and recalibrated regional groundwater model (Version 8) that includes Year 10 forecast remediation milestones, and CCS water quality management information and results.

This report also includes an evaluation of the effectiveness of the RWS (Appendix I) within the context of the objectives of the CA and CO over the first 5 years of remedial operations, and a prospective evaluation of the RWS capacity to continue removing hypersaline groundwater from the Biscayne aquifer and retracting the existing hypersaline plume eastward towards the L-31E canal. This evaluation includes estimated milestones of further remediation, and includes recommendations for modifications to the project components, monitoring, and reporting that further the objectives of the CA and CO for agency review and approval.

The following is a summary of the major findings resulting from the fifth year of remedial actions:

Approximately 6.29 billion gallons of hypersaline water and 2.37 billion pounds of salt were removed from the RWS and UICPW during Year 5. Since inception of the remediation system, approximately 29.72 billion gallons of hypersaline groundwater and 11.61 billion pounds of salt have been extracted from the Biscayne aquifer.

7-1

FPL Turkey Point RAASR Year 5 N ovem ber 2023 7. Sum m ary and Recom m endations

The RWS operated 95.8% of the reporting period, s a 2% increase in runtime compared to the previous reporting period. There were 364 hours0.00421 days 0.101 hours 6.018518e-4 weeks 1.38502e-4 months (equivalent to 15.2 days or 4.2%)

when the entire system was shut off for testing, maintenance, system enhancements, and the CSEM survey.

The average annual salinity in the CCS reached 34 PSU on September 23, 2022; and the annual rolling average has remained below 34 PSU since September 24, 2022, eliminating the CCS as a source of hypersaline recharge to groundwater for over one year and resulting in significant reductions in shallow groundwater salinity beneath the CCS.

Groundwater monitoring to assess RWS performance was conducted on 40 wells west and north of the CCS. Most hypersaline wells have a statistically significant declining trend in salinity and chloride concentrations since the start of the RWS, with many of them showing new record low values in Year 5.

The greatest reductions in saltwater concentrations in the monitoring wells have generally occurred in the area west of the northern portion of the CCS in well clusters TPGW-1, TPGW-15, TPGW-18, and TPGW-19, depending on depth.

All but one of the original hypersaline shallow monitoring wells are no longer hypersaline; and greater declines in saltwater constituents in the intermediate depth wells have occurred during the reporting period, with one intermediate well transitioning from hypersaline to saline and a second on the verge of becoming saline. Chloride and salinity reductions in intermediate depth monitor wells west of the hypersaline plume at distances more than 3 miles west of the RWS support groundwater modeling findings that the RWS operations have both halted and are reversing areas where G-II groundwaters were impaired by westward hypersaline migration prior to RWS operations.

Revisions to the approach used to convert AEM bulk resistivity to chloride concentrations were implemented in this years survey to address year to year drift and uncertainty intrinsic to both AEM resistivity and lab chloride data. The results are more mathematically robust and reduce uncertainty in previous plume estimations while improving the mathematical confidence of the results. Despite these improvements, significant unresolved variances remain that will be the focus of further evaluation in subsequent surveys.

Utilizing alternative methods for calculating hypersaline groundwater volumes resulting from technical discussions with MDC, AEM surveys evaluated over the first 5 years of RWS operations confirm statistically valid reductions have occurred to the volumetric extent of the hypersaline plume west and north of the FPL property, albeit to a lesser magnitude than calculated in Year 4.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 7. Sum m ary and Recom m endations

Implementation of recommendations for groundwater model updates from the Year 4 RAASR have resulted in better alignment of the V8 groundwater model plume orientation with monitoring well and AEM results.

The updated and calibrated Year 5 V8 groundwater model, monitoring data, and AEM data show greater plume reductions have been achieved through Year 5 and are predicted to occur by Year 10 than were expected in 2016 when the RWS remediation was approved by the agencies.

Despite remediation progress, the Year 5 model confirms the 2016 finding that while full retraction of the plume is predicted to occur in shallow and intermediate model layers (upper two-thirds of the aquifer) by 2028, full retraction to the L-31E canal along the base of the aquifer is not anticipated to occur by Year 10.

In addition to the RWS operation and reduction in groundwater hypersalinity to the west and north of the CCS, continued implementation of the salinity management, nutrient management, and thermal efficiency plans outlined in the CA and the CO have resulted in tangible improvements within the CCS including:

The annual average salinity in the CCS has been below the CO target of 34 PSU for more than 400 days. Lowering salinities in the CCS reduces the formation of hypersaline water and the driving head on hypersaline groundwater beneath the CCS, aiding in the retraction of the hypersaline plume.

CCS thermal efficiencies have exceeded the CO minimum value of 70% since 2016, with the annual average CCS thermal efficiency from June 2022 through May 2023 being 85.0% (FPL 2023a).

TN and TP concentrations show statistically significant declining trends over the past 4 plus years, with TN values consistently below 5 mg/L for the past 2 years, and TP values dropping occasionally below 0.010 mg/L since June 2023. While not applicable yet provided for context, 0.010 mg/L TP is the healthy target for the Greater Everglades.

Algae, which have dominated the CCS since 2014, have dramatically declined over the past 2 years, reaching their lowest levels ever recorded during the reporting period. Record lows in turbidity and record highs in water clarity were also recorded during Year 5, coincident with the algae reduction.

Salinity, nutrient, and thermal management actions appear to be driving the CCS ecosystem towards a new equilibrium that is currently characterized by lower algal densities, lower particulate nutrient loads, improved water clarity, and coincident increases in biodiversity, including expanding seagrasses and increasing crocodile utilization, all of which have been documented over the past 3 years.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 7. Sum m ary and Recom m endations The following is a summary of the major findings presented in the Turkey Point Groundwater Remediation Project Year 5 Recovery Well System Evaluation Report (Appendix I):

Data and analyses covering the first 5 years of remediation demonstrate the RWS has reduced the rate and halted migration of CCS-sourced hypersaline groundwater west and north of the CCS.

Data and analyses covering the first 5 years of remediation demonstrate the RWS has reduced the volumetric extent and salt mass of the hypersaline plume west and north of the CCS.

Data and analyses covering the first 5 years of remediation demonstrate that FPL has ceased discharges from the CCS that impair the reasonable and beneficial use of G-II groundwaters and that the RWS has removed the hypersaline plumes influence on the saltwater interface.

Data and analyses covering the first 5 years of remediation demonstrate the RWS has operated without negative impact on the environment.

While further remediation is achievable over the next 5 years, full retraction of the existing hypersaline plume to the L-31E canal is unlikely after ten years of RWS operation.

Nine additional conceptual remediation alternatives were formulated and evaluated against the approved RWS plan in terms of prospective plume retraction, environmental impacts, and costs. FPL recommends Alternative 1; modifications to the RWS including increased withdrawal flexibility and hardening of project components for long term operations, along with revisions to current monitoring and report, for agency review and approval.

7.2 RECOMMENDATIONS FPL recommends agency approval of Alternative 1 to improve the remediation project relative to the performance measure of retracting the existing plume towards the L-31E canal. FPL will continue to operate the RWS as currently approved during agency review of FPLs proposal.

FPL is considering the following actions:

Use test wells to evaluate the nature of AEM isolated lenses of hypersalinity in the southwest portion of the compliance area in layers 9 and 10, salinity along the base of the aquifer, and groundwater salinity in areas characterized by switching hypersaline voxels to better inform remediation progress along the western extent of the plume.

Attempt to reduce uncertainty in AEM-based plume volume estimates by correlating AEM resistivity to salinity instead of chloride because salinity measurements vary less quarter-to-quarter than chloride data.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 7. Sum m ary and Recom m endations

Continue to monitor CCS salinities and climate conditions and update/recalibrate the model with more data reflective of longer RWS operations. The longer period of RWS operation and consequent changes to salinities over a progressively larger area will help inform the model and increase its accuracy in simulating the effect of the RWS and forecasting longer-term performance.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 8. References 8 REFERENCES Duan 1983. Smearing method: A nonparametric retransformation method. Journal of the American Statistical Association, 78, 605-610.

ENERCON. 2016. PTN Cooling Canal System, Electromagnetic Conductance Geophysical Survey, Draft Final Report, Florida Power and Light Turkey Point Power Plant, 9700 SW 344th Street, Homestead, FL 33035.

Efron, Bradley. 1979. Bootstrap Methods: Another Look at the Jackknife. Annals of Statistics 7:

1-26.

Efron, Bradley, and Rob Tibshirani. 1986. Bootstrap Measures for Standard Errors, Confidence Intervals, and Other Measures of Statistical Accuracy. Statistical Science 1: 54-77.

Fish, J.E. and M. Stewart. 1991. Hydrogeology, aquifer characteristics, and ground-water flow of the surficial aquifer system, Dade County, Florida. U.S. Geological Survey, Water Resources Inv. 91-4000.

Fisher, R. A. 1935. Design of Experiments. Hafner: NY.

Fitterman, D.V. and S.T. Prinos. 2011. Results of time-domain electromagnetic soundings in Miami-Dade and Southern Broward Counties, Florida. U.S. Geological Society Open- File Report 2011-1299, ix, 42 p.

Fitterman, D.V., M. Deszcz-Pan, and T. Scott. 2012. Helicopter Electromagnetic Survey of the Model Land Area, Southeastern Miami-Dade County, Florida. U.S. Geological Society Open-File Report 2012-1176:77.

Florida Power & Light Company (FPL). 2012. Florida Power & Light Company Comprehensive Pre-Uprate Monitoring Report for the Turkey Point Monitoring Project.

Prepared for Florida Power & Light Company by Ecology and Environment, Inc. October 31, 2012.

. 2013. Florida Power & Light Company Quality Assurance Project Plan (QAPP) for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Ecology and Environment, Inc. June 2013.

. 2016a. Florida Power & Light Company Comprehensive Post-Uprate Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Ecology and Environment, Inc. March 2016.

. 2016b. Turkey Point Cooling Canal System Nutrient Management Plan. September 2016.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 8. References

. 2016c. Turkey Point Cooling Canal Thermal Efficiency Plan. December 2016.

. 2017. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Ecology and Environment, Inc. September 2017.

. 2018a. Florida Power & Light Company Recovery Well System Startup Report.

Prepared for Florida Power & Light Company by Ecology and Environment, Inc. October 2018.

. 2018b. Florida Power & Light Company Turkey Point Recovery Well System (RWS)

Second Quarter Status Report. December 2018.

. 2018c. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Ecology and Environment, Inc. August 2018.

. 2019a. Florida Power & Light Company Turkey Point Recovery Well System (RWS)

Third Quarter Status Report. March 2019.

. 2019b. Florida Power & Light Company Turkey Point Recovery Well System (RWS)

Fourth Quarter Status Report. June 2019.

. 2019c. Florida Power & Light Company Turkey Point Remedial Action Annual Status Report. November 2019.

. 2019d. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Ecology and Environment, Inc. August 2019.

. 2020a. Florida Power & Light Company Turkey Point Remedial Action Annual Status Report, Year 2, Part 1. Prepared for Florida Power & Light Company by WSP. November 2020.

. 2020b. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Ecology and Environment, Inc.

. 2021a. Florida Power & Light Company Turkey Point Remedial Action Annual Status Report, Year 2, Part 2. Prepared for Florida Power & Light Company by Stantec. April 2021.

. 2021b. Florida Power & Light Company Turkey Point Remedial Action Annual Status Report. Prepared for Florida Power & Light Company by Stantec. November 2021.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 8. References

. 2021c. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Stantec.

August 2021.

. 2022a. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Stantec.

August 2022.

______. 2022b. Florida Power & Light Company Turkey Remedial Action Annual Summary Report Year 4. November 2022.

______.. 2023a. Florida Power & Light Company Annual Monitoring Report for the Turkey Point Monitoring Project. Prepared for Florida Power & Light Company by Stantec. August 2023.

______. 2023b. Florida Power & Light Company Quality Assurance Project Plan (QAPP) for the Turkey Point Monitoring Project. Draft prepared for Florida Power & Light Company by Stantec, Inc. Submitted to the SFWMD in August 2023.

GTI (Groundwater Tec, Inc.). 2023. Review of FPLs RAASR Year 4 and The Variable Density Groundwater Flow and Solute Transport Model (v7). Prepared for Miami-Dade County Division of Environmental and Resources Management.

Hughes J.D. and White, J.T. 2014. Hydrologic Conditions in Urban Miami-Dade County, Florida, and the Effect of Groundwater Pumpage and Increased Sea Level on Canal Leakage and Regional Groundwater Flow. U.S. Geological Survey Scientific Investigations Report 2014-5162, 175 pp. https://doi.org/10.3133/sir20145162.

JLA Geoscience, Inc. 2010. Geology and Hydrogeology Report for FPL, Turkey Point Plant Groundwater, Surface Water, and Ecological Monitoring Plan, FPL, Turkey Point Plant, Homestead, Florida. Prepared for Florida Power & Light Company. October 2010.

JLA Geosciences, Inc. 2022. Core Permeability Estimation - TPGW and RWS Wells - Layer Subdivisions, Technical Memorandum. June 30, 2022.

Langevin, C.D., Thore, D.T., Dausman A.M., Sukop, M.C., and Guo, W., 2008. SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport: USGS Techniques and Methods Book 6, Chapter A22, 39 p.

National Oceanic and Atmospheric Administration, National Weather Service. Accessed October 2023. https://www.weather.gov/wrh/Climate?wfo=mfl Pitman, E. J. G. 1937. Significance Tests Which May Be Applied to Samples from Any Population. Royal Statistical Society Supplement 4: 119-30, 225-32.

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FPL Turkey Point RAASR Year 5 N ovem ber 2023 8. References Prinos, S.T., M.A. Wacker, K.J. Cunningham, and D.V. Fitterman. 2014. Origins and delineation of saltwater intrusion in the Biscayne aquifer and changes in the distribution of saltwater in Miami-Dade County, Florida. U.S. Geological Survey Scientific Investigations Report 2014-5025. 101 pp. http://dx.doi.org/10.3133/sir20145025.

SFNRC (South Florida Natural Resources Center). 2012. Hydrology and Salinity of Florida Bay. Status and trends: 1990-2009. Technical Series 2012:1.

Schamper, C., E. Auken, and K. Sorensen, 2014, Coil response inversion for very early time modelling of helicopter-borne time-domain electromagnetic data and mapping of near-surface geologic layers: European Association of Geoscientists & Engineers, Geophysical Prospecting, 62, No.3, p.658-674. https://doi.org/10.1111/1365-2478.12104.

SFWMD (South Florida Water Management District). 2015. Applicants Handbook for Water Use Permit Applications within the South Florida Water Management District.

Stringer, C.E., M.C. Rains, S. Kruse, and D. Whigham. 2010. Controls on water levels and salinity in a barrier island mangrove, Indian River Lagoon, Florida. Wetlands. 30(4):725-734.

Tetra Tech, 2016. A Groundwater Flow and Salt Transport Model of the Biscayne Aquifer, Technical Memorandum provided to Florida Power & Light, June 10, 2016.

United States Environmental Protection Agency, 2009. Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities Unified Guidance.

______. Climate Change Indicators: Sea Level Rise. Updated July 2022, accessed website October 2023. https://www.epa.gov/climate-indicators/climate-change-indicators-sea-level#:~:text=When%20averaged%20over%20all%20of,as%20the%20long%2Dterm%20tr end.

Wacker 2010. Tools and Data Acquisition of Borehole Geophysical Logging for the Florida Power & Light Company Turkey Point Power Plant in Support of a Groundwater, Surface-Water, and Ecological Monitoring Plan, Miami-Dade County, Florida: U.S. Geological Survey Open-File Report 2010-1260, 5 p., plus appendix, https://pubs.usgs.gov/of/2010/1260 Zheng, C., and Wang, P., 1998. MT3DMS - Documentation and Users Guide, U.S. Army Corps of Engineers Waterways Experiment Station Technical Report, 214 p.

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1.1 BACKGROUND

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4.1 INTRODUCTION

4.2 BACKGROUND

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