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Home My WebLink AboutCape Fear CBE_Closure Plan_Rev1_20200402wood. April 2, 2020 ELECTRONIC MAIL Ms. Sheila Holman Assistant Secretary for Environment North Carolina Department of Environmental Quality 1611 Mail Service Center Raleigh, North Carolina 27699-1611 Subject: Cape Fear Station Ash Basin Closure Plan Revision Dear Ms. Holman: In accordance with the requirements of N.C.G.S. § 130A-309. 214(a)(4), Duke Energy provides the enclosed revised plan for basin closure by excavation. Errata Sheets reflecting replacement language for the following sections are attached to this letter. • Cover Sheet • Section 3.1.6 pg. 5 • Section 3.2.2 pg. 6 • Section 3.3 pg. 6 • Section 4.2 pg. 7 • Section 4.3 pg. 7 • Section 4.5 pg. 8 • Section 4.6 pg. 8 • Section 4.7 pg. 8 • Section 4.8 pg. 8 • Section 5.0 pg. 9 • Section 5.1 pg. 9 • Section 5.2 pg. 9 • Section 5.3 pg. 9 • Section 11.1 pg. 15 Replace Cover Sheet, Page 5, Page 6, Page 7, Page 8, Page 9, and Page 15. Duke Energy remains committed to safely and permanently closing basins in ways that continue to protect people and the environment and welcomes the opportunity to work constructively with NCDEQ to move fQo 11111///l/ �'� C ^ . • A ROB Sincerely, .� �LAL <• 022943 •:y = William A. WilliaChristopher T. Keenan, PE Senior Civil EngineiMA•w�� Senior Associate Engineer 1/1111110 Wood Environment & Infrastructure Solutions 4021 Stirrup Creek Drive, Suite 100 Registered in North Carolina Durham, North Carolina 27703 Engineering and Land Surveying License No. F-1253 919-381-9900 Geology License No. C-247 woodplc.com Cabe Fear Steam Station Errata Summa Section Change Cover Rev. 1, date, seal 3.1.6 Add Section Heading: 3.1.6 Inspection and Monitoring Summary 3.2.2 This information was submitted to NCDEQ in September 2016 as part of the Update to Drinking Water Well and Receptor Survey for Cape Fear Steam Station prepared separately for Duke Energy. The Update to Drinking Water Well and Receptor Survey document is herein incorporated by this reference, but its content was not prepared by Wood. 3.3 This information was submitted to NCDEQ on July 30, 2019 as part of the CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. The CAMA Annual Interim Report is herein incorporated by this reference, but its content was not prepared by Wood. Locations of the existing groundwater monitoring wells are shown in Figure 4 of the Closure Plan Drawings included in Appendix D, but the CAMA Annual Interim Report should be consulted for details of well locations, names, and status. 4.2 This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 4_3 This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 4.5 This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 4.6 Duke Energy provides CAMA groundwater monitoring results to NCDEQ on a quarterly basis. Additionally, historical groundwater monitoring results have been submitted in multiple reports such as the September 2015 CSA, the September 2016 CSA Supplement 1, and the 2018 CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. These documents are herein incorporated by this reference but were not prepared by Wood. 4.7 Groundwater level maps for each designated flow zone were submitted to NCDEQ on July 30, 2019 as part of the CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. The CAMA Annual Interim Report is herein incorporated by this reference, but its content was not prepared by Wood. 4.8 This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 5_0 This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 5.1 This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 5_2 This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 5.3 This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 11.1 This information was submitted to NCDEQ on July 30, 2019 as part of the CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. The CAMA Annual Interim Report is herein incorporated by this reference, but its content was not prepared by Wood. DUKE ENERGY CAPE FEAR STATION COAL COMBUSTION RESIDUALS SURFACE IMPOUNDMENT CLOSURE PLAN CLOSURE BY EXCAVATION 1956 Ash Basin 1963/1970 Ash Basin 1978 Ash Basin 1985 Ash Basin Closure Plan Report Final Submittal Prepared for DUKE ENERGY. 550 South Tryon Street Charlotte, North Carolina 28202 Revision 1 Issue Date: 2 April 2020 Prepared by Wood Environment & Infrastructure Solutions, Inc. 4021 Stirrup Creek Drive, Suite 100 Durham, North Carolina 27703 Project No. 7812180071 wood. 022943 co Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan TABLE OF CONTENTS wood. EXECUTIVE SUMMARY............................................................................................iv 1.0 INTRODUCTION............................................................................................................... 1 1.1 Background...................................................................................................................................1 1.2 Closure Plan Objectives............................................................................................................... 1 1.3 Report Organization...................................................................................................................... 2 2.0 GOVERNING LAWS......................................................................................................... 2 3.0 FACILITY DESCRIPTION AND EXISTING SITE FEATURES .......................................... 3 3.1 Surface Impoundment Description............................................................................................... 3 3.1.1 Site History and Operations................................................................................................ 3 3.1.2 Estimated Volume of CCR in Impoundments.....................................................................3 3.1.3 Description of Surface Impoundments Structural Integrity.................................................4 3.1.4 Sources of Discharges into Surface Impoundments...........................................................5 3.1.5 Existing Liner System.......................................................................................................... 5 3.1.6 Inspection and Monitoring Summary..................................................................................5 3.2 Site Maps...................................................................................................................................... 6 3.2.1 Summary of Existing CCR Impoundment Related Structures............................................6 3.2.2 Receptor Survey.................................................................................................................6 3.2.3 Existing On -Site Landfills.................................................................................................... 6 3.3 Monitoring and Sampling Location Plan....................................................................................... 6 4.0 RESULTS OF HYDROGEOLOGIC, GEOLOGIC, AND GEOTECHNICAL INVESTIGATIONS............................................................................................................ 6 4.1 Background...................................................................................................................................6 4.2 Hydrogeology and Geologic Descriptions.................................................................................... 7 4.3 Stratigraphy of the Geologic Units Underlying Surface Impoundments ....................................... 7 4.4 Geotechnical Properties............................................................................................................... 7 4.4.1 CCR Within Ash Basins......................................................................................................7 4.4.2 Liner Material Properties.....................................................................................................8 4.4.3 Subsurface Soil Properties.................................................................................................8 4.5 Chemical Analysis of Impoundment Water, CCR and CCR Affected Soil .................................... 8 4.6 Historical Groundwater Sampling Results.................................................................................... 8 4.7 Groundwater Potentiometric Contour Maps................................................................................. 8 4.8 Estimated Vertical and Horizontal Extent of CCR within the Impoundments ............................... 8 5.0 GROUNDWATER MODELING ANALYSIS...................................................................... 9 5.1 Site Conceptual Model.................................................................................................................. 9 5.2 Geochemical Site Conceptual Model............................................................................................ 9 5.3 Groundwater Trend Analysis........................................................................................................ 9 6.0 BENEFICIAL USE AND FUTURE USE............................................................................ 9 6ACCR Beneficial Use...................................................................................................................... 9 6.2 Site Future Use............................................................................................................................. 9 Rev. 0 11 December 2019 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. 7.0 CLOSURE DESIGN DOCUMENTS.................................................................................. 9 7.1 Engineering Evaluations and Analyses...................................................................................... 10 7.2 Closure Plan Activities................................................................................................................ 10 7.3 Design Drawings......................................................................................................................... 11 7A Description of Construction Quality Assurance and Plan........................................................... 11 8.0 MANAGEMENT OF WASTEWATER AND STORMWATER...........................................12 8.1 Anticipated Changes in Wastewater and Stormwater Management .......................................... 13 6.2 Wastewater and Storm water Permitting Requirements.............................................................. 14 9.0 DESCRIPTION OF FINAL DISPOSITION OF CCR.........................................................14 10.0 APPLICABLE PERMITS FOR CLOSURE.......................................................................14 11.0 DESCRIPTION OF POST -CLOSURE MONITORING AND CARE..................................14 11.1 Groundwater Monitoring Program.............................................................................................. 15 12.0 PROJECT MILESTONES AND COST ESTIMATES........................................................15 12.1 Project Schedule......................................................................................................................... 15 12.2 Closure and Post -Closure Cost Estimate................................................................................... 15 13.0 REFERENCES.................................................................................................................17 Tables Table 2-1 CAMA Closure Plan Requirements Summary and Cross Reference Table Table 4-1 Summary of Typical Material Properties Table 10-1 Cape Fear Plant Regulatory Permits, Approvals, or Requirements for Ash Basin Closure by Excavation Fi ures Figure 1-1 Vicinity Map and Site Plan Figure 1-2 Overall Existing Conditions Plan Appendices Appendix A Estimated Volume of CCR in Impoundment Appendix B Geotechnical Data and Properties Appendix C Engineering Evaluations and Analyses Appendix D Closure Plan Drawings Appendix E Excavation Soil Sampling Plan Rev. 0 11 December 2019 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan EXECUTIVE SUMMARY In accordance with N.C.G.S. § 130A-309.214(a)(4), Duke Energy has prepared this Closure Plan to describe the closure of the coal combustion residuals (CCR) surface impoundments (Basins) at the Cape Fear Station. The Cape Fear Station Basins closure will consist of closure by excavation, whereby CCR in the Basins will be excavated, processed, and transported off -site for beneficial re -use as a concrete amendment. The removal of CCR and closure of the Basins will be in accordance with all applicable provisions of the North Carolina Coal Ash Management Act of 2014, Sess. L. 2014-122, as amended (codified at N.C.G.S. § 130A-309.200, et seq.) (CAMA). CCR processing will be done using on -site STAR' (Staged Turbulent Air Reactor) Technology, a patented thermal beneficiation process to transform coal ash from CCR surface impoundments into a high -quality, sustainable product for the concrete industry. Duke Energy will periodically review the progress of the excavation and STAR' processing as it relates to achieving full CCR removal by the required end date of October 1, 2028 for 1956, 1963 and 1970 Ash Basins and October 1, 2029 for the 1978 and 1985 Ponds. Duke Energy will implement a concurrent excavation plan in which the remaining excavated CCR will be transported to an approved landfill facility in order to meet the end date of October 1, 2029 for complete removal. The Cape Fear Station is owned and operated by Duke Energy Progress, LLC (Duke Energy). The approximately 483-acre Cape Fear Station site is located 500 CP&L Road in Chatham County, Moncure, North Carolina, on the eastern bank of the Cape Fear River. The plant initially began power production operations in 1923. Additional power generating units were added from 1924 to 1969. In the most recent operating configuration, the plant employed two coal-fired units along with four oil -fueled combustion turbine units. Power production operations at the plant were terminated in October 2012, and demolition activities were completed in 2017. There are no coal-fired units currently in operation at the Cape Fear Station. This Closure Plan covers the Basins located at the Cape Fear Plant, identified in the North Carolina Department of Environmental Quality (NCDEQ) Dam Safety Inventory as follows: • 1956 Ash Basin Dike (NC Dam Safety ID CHATH-075) • 1963 Ash Basin Dike (NC Dam Safety ID CHATH-076) • 1970 Ash Basin Dike (NC Dam Safety ID CHATH-077) • 1978 Ash Basin Dike (NC Dam Safety ID CHATH-078) • 1985 Ash Basin Dike (NC Dam Safety ID CHATH-079) The Basins at the Cape Fear Plant were all constructed as raised dike basins, with excavated soils from within the Basins to construct the dikes. During operation, fly ash, bottom ash, coal slag, unburned coal, and stormwater from the plant were transported from the plant to the facility's Basins by hydraulic (wet) sluicing. With the permanent retirement of the coal-fired generating units, there are no longer any CCR disposal operations within the Basins. The Basins are unlined and the maximum depth of CCR within these basins varies between 20 and 40 feet. Information provided by Duke Energy (with updated CCR inventory data through July 31, 2019) indicates that the current estimated volume of ash in the Basins is approximately 5.765 Rev. 0 11 December 2019 iv Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan million tons (4.804 million cubic yards assuming a conversion factor of 1.2 tons/cy). It should be noted that the CCR volume/tonnage estimates are approximations since they are based on assumed pre -basin grades. Upon approval of the Closure Plan by NCDEQ, additional activities to complete closure of the Basins will commence, including beginning excavation of the CCR from the Basins, establishing final grades using soil fill where required to properly drain the Basin areas, breaching/removing the Basin dikes following removal of CCR (soil material removed from the Basin dikes will remain on -site and will be incorporated into the final site grading plan), and development of stormwater features and vegetative covers. This document also includes a description of the future Post -Closure Care Plan, which will provide a description of the inspection, monitoring, and maintenance activities required to be performed for the Cape Fear Station site for a minimum of 30 years. This document provides a summary of properties of the site, as well as geotechnical properties of CCR and natural soils to support engineering analyses of the closure design. These analyses indicate that closure by excavation, as detailed in the Closure Plan, meets regulatory requirements for the stability of the site, management of stormwater runoff, and access for effective maintenance over the post -closure care period. In a letter dated April 5, 2019, NCDEQ established submittal dates for an updated Comprehensive Site Assessment (CSA) and updated Corrective Action Plan (CAP) for CCR surface impoundments and other primary and secondary sources. Consistent with this direction, Duke Energy will submit to NCDEQ the updated CSA for Cape Fear by September 1, 2020, and the updated CAP by June 1, 2021. The CAP sets out corrective action measures for the restoration of groundwater quality as required under CAMA and the state's groundwater quality regulations. Although the Closure Plan contains references to the CAP, all specific relevant details to groundwater and related actions will be contained in the CAP itself and not in this Closure Plan. Rev. 0 11 December 2019 v Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan 1.0 INTRODUCTION 1.1 Background The approximately 483-acre Cape Fear Station site is located at 500 CP&L Road in Chatham County, Moncure, North Carolina, adjacent to the Cape Fear River and south of the confluence of the Haw and Deep Rivers. Commercial operations of the station began power production in 1923 with two coal-fired units. Additional power generating units were added from 1924 to 1969. Power production operations at the Cape Fear Station were terminated in October 2012, ceasing all waste flows at that time. Demolition activities were completed in 2017. This Closure Plan is being submitted for approval by NCDEQ and reflects closure by excavation of the CCR from the Cape Fear Station site. Processing of the excavated CCR will be done using STAR' Technology, a patented thermal beneficiation process to transform coal ash from CCR surface impoundments into a high -quality, sustainable product for the concrete industry. Figure 1-1 presents a Vicinity Map and Site Plan of the Cape Fear Station. The Cape Fear Station has five regulated impoundment structures (Figures 1-1 and 1-2). This Closure Plan covers the Basins located at the Cape Fear Station that are identified (and regulated by) the North Carolina Department of Environmental Quality (NCDEQ) and Dam Safety as follows: • 1956 Ash Basin Dike (NC Dam Safety ID CHATH-075) • 1963 Ash Basin Dike (NC Dam Safety ID CHATH-076) • 1970 Ash Basin Dike (NC Dam Safety ID CHATH-077) • 1978 Ash Basin Dike (NC Dam Safety ID CHATH-078) • 1985 Ash Basin Dike (NC Dam Safety ID CHATH-079) This Closure Plan has been prepared for the review and approval of NCDEQ. 1.2 Closure Plan Objectives The primary objective of this Closure Plan is to address the closure by excavation of the CCR from the Basins at the Cape Fear Station pursuant to North Carolina Coal Ash Management Act of 2014, Session L. 2014-122, as amended (CAMA). A further objective is to obtain approval from NCDEQ to proceed and develop the additional details (as described further within this Closure Plan) and working documents necessary to complete the closure actions. Duke Energy is requesting approval of this Closure Plan with the knowledge that other details will follow. This Closure Plan describes and communicates the key actions and activities necessary to close the Basins in accordance with the requirements for written closure plans for CCR surface impoundments in N.C.G.S. § 130A-309.214(a)(4). Planned closure activities include: • Removal of free water/bulk water volume via permitted outfall (i.e., decanting) • Construction and operation of a temporary water management (WMS) system to manage discharges in compliance with the NPDES permit during closure • Construction of haul roads and STAR' Unit for processing of CCR for beneficial re -use • Development of sump areas in the Basins to collect and convey waters to the water management system Rev. 0 11 December 2019 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan • Dewatering the CCR to allow for safe access. CCR excavation and conditioning will be required prior to transport to the on -site STAR° system • Excavate CCR from the Basins, with sequencing determined for optimal progression. Instrumentation and monitoring requirements to be developed prior to construction will be followed to verify construction phase stability. Construction dewatering to be used as needed to provide stable work areas and slopes • Complete closure by excavation verification • Breaching of the Basin dikes • Grading the perimeter dikes into each of the basins with a grading plan that will establish drainage to promote flow of stormwater out of the Basins in a manner protective of area soils and water 1.3 Report Organization This document is structured to follow the requirements of N.C.G.S. § 130A-309.214(a)(4). 2.0 GOVERNING LAWS In August 2014, the North Carolina General Assembly enacted CAMA, which contains specific statutory requirements applicable to CCR surface impoundments. Relative to the Cape Fear Station, "coal combustion residuals surface impoundment," as defined in N.C.G.S. § 130A- 309.201(6), is interpreted to include the plant's Basins. In July 2016, the North Carolina General Assembly enacted House Bill 630, which added N.C.G.S. § 130A-309.216 requiring Duke Energy to identify three sites in North Carolina at which to install and operate Ash Beneficiation projects capable of processing CCR to specifications appropriate for cementitious products. The statute requires Duke Energy to use commercially reasonable efforts to produce 300,000 tons of useable ash at each site annually. On October 5, 2016, Duke Energy selected the Cape Fear Station as one of the Ash Beneficiation sites. Pursuant to subsection (c) of N.C.G.S. § 130A-309.216, CCR surface impoundments located at a site at which an Ash Beneficiation project is installed and operating, shall be closed no later than August 1, 2028. The Excavation Soil Sampling Plan for the Cape Fear Station (presented in Appendix E), represents activities to satisfy the requirements set forth in the NCDEQ's November 4, 2016 letter and attachment titled "CCR Surface Impoundment Closure Guidelines for Protection of Groundwater." In a letter dated April 5, 2019, NCDEQ established submittal dates for an updated Comprehensive Site Assessment (CSA) and updated Corrective Action Plan (CAP) for CCR surface impoundments and other primary and secondary sources. Consistent with this direction, Duke Energy will submit to NCDEQ the updated CSA for the Cape Fear Station by September 1, 2020, and the updated CAP by June 1, 2021. In addition to the above requirements, National Pollutant Discharge Elimination System (NPDES) permit program compliance, Special Order by Consent (which commits Duke Energy to initiate and complete decanting of the Basins by dates certain) compliance, dam safety approvals for Rev. 0 11 December 2019 2 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. modifications to regulated CCR basin dikes, and environmental permitting requirements must be considered as part of closure. 3.0 FACILITY DESCRIPTION AND EXISTING SITE FEATURES 3.1 Surface Impoundment Description This section provides details on the CCR-related features at the Cape Fear Station. 3.1.1 Site History and Operations Figure 1-1 shows locations of the Cape Fear Station and 1956 (CHATH-075), 1963 (CHATH- 076), 1970 (CHATH-077), 1978 (CHATH-078), and 1985 (CHATH-079) Basins. Figure 1-2 shows the overall existing conditions at the Cape Fear Station. The Cape Fear Station is located on the east bank of the Cape Fear River in Chatham County, Moncure, North Carolina. Review of available information indicates that the property, consisting of approximately 483 acres, is owned by Duke Energy, and is reported to have begun commercial operation in 1923. Additional power generating units were added from 1924 to 1969. The CCR Basins were constructed at the site between 1956 and 1985 as operational needs required additional CCR disposal area. Sluicing of ash to the basins ceased in 2012. Process and waste waters continued to be treated thru the 1978 and 1985 Ash Basins until 2015. In the most recent operating configuration, the Cape Fear Station employed two coal-fired units along with four oil - fueled combustion turbine units. A cooling water discharge channel is present in the middle portion of the Cape Fear Station. The discharge channel extends to an unnamed tributary to the Cape Fear River. All power generating operations were terminated at the Cape Fear Station in October 2012 and demolition was completed in 2017. There are no longer any CCR disposal operations within the Basins with the permanent retirement of the coal-fired units. The Basins at the Cape Fear Station are surrounded by perimeter dikes such that no external stormwater flows into the Basins. 3.1.2 Estimated Volume of CCR in Impoundments Based on CCR inventory data provided by Duke Energy as of July 31, 2019 the approximate volume of CCR in the Ash Basin is listed in the table below. To compute the estimated volume of CCR in place an assumed density of 1.2 tons per cubic yard was used, which is the Duke Energy fleet wide assumption. See Appendix A for the Estimated Volume of CCR Material in the Impoundment data sheet. Rev. 0 11 December 2019 3 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. Impoundment Estimated CCR Material Volume (Cy) Estimated CCR Material Weight (tons)* 1956 Ash Basin 349,167 419,000 1963 Ash Basin 715,833 859,000 1970 Ash Basin 699,167 839,000 1978 Ash Basin 694,167 833,000 1985 Ash Basin 2,345,833 2,815,000 TOTAL 4,804,167 5,765,000 * Estimated CCR Material is based on updated CCR Inventory Data provided by Duke Energy as of July 31, 2019. To compute the estimated mass of CCR in place an assumed density of 1.2 tons per cubic yard was used, which is the Duke Energy fleet wide assumption. 3.1.3 Description of Surface Impoundments Structural Integrity The purpose of this section is to summarize the Basins' structural integrity evaluations based on current existing information. This section includes brief summaries of the Geotechnical and Hydrology and Hydraulics (H&H) capacity analyses results. Duke Energy provided Wood with pertinent information regarding the integrity of the embankments, which had already been compiled and analyzed. In summary, the structural integrity of the Basins and subsequent dam inspection reports meet the regulatory requirements. • Slope Stability: Slope stability analysis completed for the identified critical cross sections for each of the dikes indicate that the minimum factors of safety meet programmatic criteria under static, pseudo - static, and post -seismic conditions. • Liquefaction Conditions (where susceptible) and Liquefaction Potential: Embankment and foundation soils associated with these dikes are not liquefaction - susceptible. The predicted deformations from these analyses are negligible, less than'/2 inch. Because the Basin dike embankments and foundation soils are not liquefaction -susceptible, Wood expects no vertical seismically -induced settlements and negligible seismically -induced shear at these structures during the Maximum Design Earthquake (MDE). • Hydrology and Hydraulics (H&H) Capacity Analyses: In April 2019, the NCDEQ promulgated new dam safety rules and, per the dam safety High Hazard Classification, each CCR Basin is required to pass a full Probable Maximum Precipitation (PMP). Each basin is classified as high hazard by NCDEQ due to the potential for environmental impacts greater than $200,000, if the Basin failed. In response, Wood performed H&H Analysis on each of the Basins at the Cape Fear site. Based upon the results of these analyses, the 1956 Ash Basin and 1963/1970 Ash Basin both overtop during the design storm event. Spillway designs have been developed for 1956 and 1963/1970 basins Rev. 0 11 December 2019 4 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan to address the requirements of the 2019 NCDEQ dam safety rules. The 1978 Ash Basin and 1985 Ash Basin both have the capacity to contain two times the design storm, and through the pumping plan (currently in place) have the capability to release 80 percent of the detained storm volume within 15 days following the design storm peak (6-hour PMP), as required by the North Carolina dam safety rules. The results of the analyses are presented in Appendix C. 3.1.4 Sources of Discharges into Surface Impoundments Duke Energy has decommissioned the coal-fired power plant at this site. Since it is now permanently retired from service, CCR is no longer sluiced into the Basins, and the Basins are inactive. Since the Basins were constructed by raised dikes, the contributing drainage area to each of the Basins consists only of the Basins themselves and the only discharges into the Basins is from direct rainfall during rain events. 3.1.5 Existing Liner System The Basins located at the Cape Fear Station do not include a geomembrane or clay liner system and are considered to be unlined. Inspection and Monitoring Summary 3.1.6 Inspection and Monitoring Summary Duke Energy conducts routine weekly, monthly, and annual inspections of the Basins, consistent with North Carolina's dam safety requirements and the federal CCR rule. Weekly Basin inspections have been on -going since 2014, and include observation of upstream slopes and shorelines, crest, downstream slopes, toe areas, and adjacent drainage way(s), spillway(s) and associated structure(s), and other structures and features of the dikes. Monthly inspections of the Basins include the weekly monitoring elements with the addition of piezometer and observation well readings; water level gauges/sensors; and visual observations and documentation of slopes and benches of the dry ash stack in the 1985 Ash Basin. Daily inspections of the Basins are not routinely required; however, on a case -by -case basis, the Basins may be inspected daily beginning at such times and continued for the duration as specified by plant management. Such daily inspections might be initiated during a repair activity on the dike or in response to a specific imposed regulatory agency requirement. The Basins are inspected annually by an independent third -party consultant. In a letter dated August 13, 2014, NCDEQ requires these inspections to be conducted annually at all of Duke Energy's CCR impoundments in North Carolina. These inspections are intended to confirm adequacy of the design, operation, and maintenance of the surface impoundments in accordance with accepted engineering standards. Reports are to be submitted to the NCDEQ within 30 days of the completion of the inspection. The results for the annual inspections are used to identify needed repairs, repair schedules, to assess the safety and operational adequacy of the dikes, and to assess compliance activities regarding applicable permits and environmental and dam regulations. Annual inspections are also performed to evaluate previous repairs. The annual inspections of the dikes have been ongoing since 2001, with 5-year inspections between 1986 and 2001. Rev. 1 2 April 2020 5 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. The 2015 through 2019 annual inspections did not identify features or conditions in the Basin dikes or their outlet structures or spillways, that indicate an imminent threat of impending failure hazard. Review of critical analyses indicated the designs conform to current engineering state of practice to a degree that no immediate actions are required other than the recent and ongoing surveillance and monitoring activities already underway. Special inspections of the Basins may be performed during episodes of high -flow, earthquake, emergency, or other extraordinary events. Visual inspections are performed after a heavy precipitation event when accumulation of four inches of rainfall or greater occurs within a 24-hour period. An internal inspection will be performed if a seismic event is felt locally or detected by the US Geological Survey measuring greater than a Magnitude 3 and with an epicenter within 50 miles of the dikes. A special inspection would also be performed during an emergency, such as when a potential dike breach condition might be identified or when construction activities (e.g., basin cleanout) are planned on or near the dikes. They are also conducted when the ongoing surveillance program identifies a condition or a trend that warrants special evaluation. 3.2 Site Maps 3.2.1 Summary of Existing CCR Impoundment Related Structures A site map showing property boundary, former location of the Cape Fear Station, and the Basins with their boundaries and topographic and bathymetric contours are shown on Figure 1-2. 3.2.2 Receptor Survey This information was submitted to NCDEQ in September 2016 as part of the Update to Drinking Water Well and Receptor Survey for Cape Fear Steam Station prepared separately for Duke Energy. The Update to Drinking Water Well and Receptor Survey document is herein incorporated by this reference, but its content was not prepared by Wood. 3.2.3 Existing On -Site Landfills There are no known on -site landfills at the Cape Fear Station. 3.3 Monitoring and Sampling Location Plan This information was submitted to NCDEQ on July 30, 2019 as part of the CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. The CAMA Annual Interim Report is herein incorporated by this reference, but its content was not prepared by Wood. Locations of the existing groundwater monitoring wells are shown in Figure 4 of the Closure Plan Drawings included in Appendix D, but the CAMA Annual Interim Report should be consulted for details of well locations, names, and status. 4.0 RESULTS OF HYDROGEOLOGIC, GEOLOGIC, AND GEOTECHNICAL INVESTIGATIONS 4.1 Background An overall boring and existing monitoring well location plan indicating the locations of recent and historical borings, monitoring wells, piezometers, and Cone Penetration Test (CPT) sounding locations is shown on Figure 4 included in Appendix D. Rev. 1 2 April 2020 6 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan This section summarizes the site geology and hydrogeology; site stratigraphy of the geologic units underlying the surface impoundments; hydraulic conductivity of CCR and the soils underlying the surface impoundment; geotechnical properties of the CCRs and the uppermost stratigraphic unit under the surface impoundment; and the CCR and CCR-affected soils. Duke Energy provided Wood with pertinent documentation regarding the site geology and hydrologic information, which had already been compiled. 4.2 Hydrogeology and Geologic Descriptions This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 4.3 Stratigraphy of the Geologic Units Underlying Surface Impoundments This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 4.4 Geotechnical Properties This section provides a summary of geotechnical conditions and properties found from investigations performed within the Basins and Basin dike areas. The presented information was obtained from previous geotechnical investigations at the site and recent investigation activities conducted to support the Closure Plan development. The geotechnical conditions within the Basins generally consist of CCR material (primarily interbedded layers of fly ash and bottom ash, along with coal slag, unburned coal, and plant stormwater) placed in the Basins primarily by hydraulic sluicing underlain by residual soil, saprolite, partially weathered rock (PWR), and bedrock. For purposes of discussion of the geotechnical properties of the materials, the saprolite material is described as residual material. General properties of the various materials encountered within and surrounding the Basins are described below. A range of measured material properties from laboratory tests performed by Wood and SynTerra for the subsurface explorations completed within the Basins is presented in Appendix B (boring locations are shown in Figure 4 of Appendix D). A summary of typical measured properties for different material types are presented in Table 4-1. A summary of laboratory tests data performed at the Cape Fear Station in support of the closure design is presented in Appendix B. 4.4.1 CCR Within the Basins The CCR within the Basins consists primarily of layers and mixtures of bottom ash and fly ash. Other CCR materials such as slag are also typically encountered. The bottom ash generally consists of very loose to loose, moist to wet, dark gray to gray, silty sand (SM) or silt and sandy silt (ML). At some drilling locations, a surficial layer of CCR fill material (SP or SW or SW-SM) was encountered that was used for boring access road construction. The fly ash generally consists of very soft to soft, moist to wet, light to medium gray sandy silt and silt (ML). Rev. 1 2 April 2020 7 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. Further information is included as part of the updated CSA being prepared separately by SynTerra for Duke Energy and will be submitted to NCDEQ by September 1, 2020. The CSA is herein incorporated by this reference, but its content is not the work product of Wood. 4.4.2 Liner Material Properties The Basins at the Cape Fear Station are unlined, so there are no associated material properties. 4.4.3 Subsurface Soil Properties Exploratory borings installed at the Cape Fear Station indicate the subsurface lithology generally consists of a fining upward sequence of unconsolidated surficial alluvial deposits unconformably atop a scoured bedrock surface comprised of sedimentary rock. • Alluvium: Alluvium is likely present as a result of deposition of sediments from the Cape Fear River and associated tributaries. The alluvium typically consists of 10 to 15 feet of clay and silts that grade into a 5- to 10-foot layer of silt, clay, and sand, which in turn grades into an approximate 5-foot layer of gravelly coarse sand directly atop weathered bedrock. Bedrock: Little, if any, "transition zone" or Partially Weathered Rock (PWR) exists along the unconformity between the alluvium and bedrock. Further, cores did not indicate a significant zone of saprolite as indurated bedrock was typically observed less than 10 feet below the unconformity of alluvium and bedrock. The bedrock consists of Triassic -age sedimentary rock (mudstone and sandstone). The residuum (including saprolite) is the next layer encountered and generally consists of soft to hard sandy lean clay (CL), silty sand (SM), and sandy silt (ML). 4.5 Chemical Analysis of Impoundment Water, CCR and CCR Affected Soil This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. 4.6 Historical Groundwater Sampling Results Duke Energy provides CAMA groundwater monitoring results to NCDEQ on a quarterly basis. Additionally, historical groundwater monitoring results have been submitted in multiple reports such as the September 2015 CSA, the September 2016 CSA Supplement 1, and the 2018 CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. These documents are herein incorporated by this reference but were not prepared by Wood. 4.7 Groundwater Potentiometric Contour Maps Groundwater level maps for each designated flow zone were submitted to NCDEQ on July 30, 2019 as part of the CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. The CAMA Annual Interim Report is herein incorporated by this reference, but its content was not prepared by Wood. 4.8 Estimated Vertical and Horizontal Extent of CCR within the Impoundments This information was submitted to NCDEQ on September 2, 2015 as part of the CSA and on September 15, 2016 in an updated CSA Supplement 1 prepared separately for Duke Energy. The CSA and CSA Supplement 1 are herein incorporated by this reference, but their content was not prepared by Wood. Rev. 1 2 April 2020 8 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan 5.0 GROUNDWATER MODELING ANALYSIS This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 5.1 Site Conceptual Model This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 5.2 Geochemical Site Conceptual Model This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 5.3 Groundwater Trend Analysis This information was submitted to NCDEQ on February 29, 2016 as part of the CAP Part 2 prepared separately for Duke Energy. The CAP Part 2 is herein incorporated by this reference, but its content was not prepared by Wood. 6.0 BENEFICIAL USE AND FUTURE USE 6.1 CCR Beneficial Use Duke Energy has developed plans for on -site recovery and reclamation/recycling of a significant portion of the CCR at the Cape Fear Station, in accordance with rate established by NCGS § 130A-309.216. Duke Energy will implement a concurrent excavation plan in which the remaining excavated CCR will be transported to an approved landfill facility in order to meet the end date of December 31, 2029 for complete removal of the CCR. The beneficial use activities consist of removing and transporting CCR from the Basins for processing at a STAR° facility to be constructed on -site to the east of the 1985 Basin. The STAR' facility will process the reclaimed CCR to a level of quality and condition suitable for future reuse in the concrete industry. 6.2 Site Future Use At this time, Duke Energy has not identified any future use of the land reclaimed by the excavation and decommissioning of the Basins. Since this Closure Plan details a closure by excavation method, no recording of a notation on the deed to the property is required. 7.0 CLOSURE DESIGN DOCUMENTS Closure of the Cape Fear Basins will be completed in two phases. Phase 1 is excavation and Phase 2 will be the final decommissioning of the Basin dikes and final grading. Rev. 1 2 April 2020 9 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan 7.1 Engineering Evaluations and Analyses Engineering evaluations and analyses to support closure of the Basins at the Cape Fear Station, as detailed in this Closure Plan, are provided in Appendix C. Based on the final post -closure configuration of the Basins and absence of engineered fill features, no geotechnical calculations accompany the Closure Plan presented herein. Calculations related to dike removal will be included in the dike modification permit applications. Safe and effective access to the Basins is critical to CCR excavation and the completion of closure. Access road locations into or across the Basins cannot be reliably established until detailed phasing of closure is developed, and a contractor is selected to complete the work. A variety of mitigation techniques can be applied, such as installation of a geogrid and crushed stone aggregate, placement and spreading of dry CCR over the basin surface to establish access and use of low ground pressure or light weight construction equipment. Areas for stockpiling or conditioning (drying) of CCR are generally needed. These areas will be established within the limits of the CCR unit and require placement or stacking of CCR excavated from other areas of the Basins. They will be established in areas where all or most of the CCR has been removed, or on areas where a significant depth of CCR remains in place. Sluiced CCR forming the foundation of stockpiles or conditioning (drying) areas may be subject to bearing capacity or slope failures from the additional vertical compressive stress imparted by the stacked CCR and hauling equipment. During excavation of CCR, interim or temporary excavated CCR slopes are commonly created. These slopes vary in height and the duration they will have to stand. Some slopes are subject to potential loading from hauling or stockpiling operations. The location and geometry of such slopes cannot be established during design. These elements depend on the means and methods employed by the construction contractor, site conditions, schedule, and other site conditions. Excavation in a deep valley fill creates significant safety risks that need further evaluation and will require the means and methods inputs from a contractor to fully address before closure excavation work commences. A detailed phasing and excavation plan will be developed after this Closure Plan is approved by NCDEQ. 7.2 Closure Plan Activities The primary activities associated with closure by excavation are as follows: • Decant by using floating pumps, screened intakes, and pumping through the on -site WMS under the existing NPDES permit • Construct the STAR° facility and required haul roads • Install stormwater diversion or retention controls to minimize stormwater flow impacts to the CCR within the Basins • Operate the on -site pumping and WMS to manage interstitial/pore water and contact stormwater during construction • Dewatering the CCR to allow for safe access. CCR excavation and conditioning will be required prior to transport to the on -site STAR' system • Start CCR excavation from the Basins, with sequencing determined for optimal progression. Instrumentation and monitoring requirements to be developed prior to Rev. 0 11 December 2019 10 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan construction will be followed to verify construction phase stability. Construction dewatering to be used as needed to provide stable work areas and slopes • Maintain required hydraulic storage capacity throughout the excavation process • Manage dusting from closure activities through the use of appropriate controls • Complete closure by excavation verification. Grade the area to promote positive drainage and seed for vegetative growth • Sequence final dike breach with inflow design flood management Additional information and details pertaining to the closure design are provided in the Closure Plan drawings, which can be found in Appendix D. 7.3 Design Drawings Four sets of Closure Plan drawings can be found in Appendix D. The sets of drawings provided are for the 1956 Basin, the 1963/1970 Basin, the 1978 Basin, and the 1985 Basin. Each set includes the following sheet for each of the Basins: • Sheet 1 — Cover sheet • Sheet 2 — General project notes • Sheet 3 — Existing conditions overall aerial • Sheet 4 — Existing conditions • Sheet 5 — Estimated bottom of ash grades • Sheet 6 — Proposed final conditions • Sheet 7 — Cross -sections These Closure Plan drawings will be further developed and refined to develop construction -level drawings during subsequent stages following NCDEQ approval of the Closure Plan. In addition, supplemental drawing sets will be prepared on an as -needed basis to support dike modification and/or decommissioning permits, erosion, and sediment control permits, NPDES permit modifications, and any other related permits. Once the excavation grades shown on the Closure Plan drawings have been achieved, the procedures described in the Duke Energy Excavation Soil Sampling Plan (Appendix E) will be followed to confirm that closure by excavation has been achieved. 7.4 Description of Construction Quality Assurance and Plan A Construction Quality Assurance (CQA) Plan will be developed following NCDEQ approval of the Closure Plan for closure of the Basins located at the Cape Fear Station site. This CQA Plan description has been prepared to address N.C.G.S. § 130A-309.214(a)(4)(g) of CAMA, and its purpose is to provide a description of the CQA program to be adhered to in execution of the final closure activities at the Cape Fear Station, being the construction of the dike breach and stormwater channels. The CQA Plan will be a component of the dam decommissioning package and will include a description of the roles and responsibilities for monitoring and testing activities and provides guidance on the methodology to be used for evaluating whether the construction has been performed in accordance with the approved Closure Plan. The CQA Plan will also detail the material testing frequencies; methods for transportation, handling, and storage of materials; test methods and verifications; manufacturer, field, and laboratory testing; field activities for Rev. 0 11 December 2019 11 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan construction monitoring and oversight; and reporting and documentation requirements. Technical specifications to be developed as part of the construction -level design packages for contractor bidding will present specific material properties and specifications. The items that will be included in the CQA Plan will address materials and CQA activities associated with the following components: • Earthwork • Stormwater Channels • HDPE Piping • As -Built Conditions • Record Documentation Report 8.0 MANAGEMENT OF WASTEWATER AND STORMWATER • Existing Wastewater and Stormwater Management The Basins at the Cape Fear site are surrounded by perimeter dikes, and stormwater runoff from adjacent areas does not enter the Basins. For the 1978 and 1985 Basins, stormwater collected within the pond surface area is pumped to a water treatment system and subsequently released to the Cape Fear River. The stormwater collected within the pond surface area for 1963/1970 Basin is currently discharged to the Cape Fear River through the discharge outlet pipe at the southwest corner of the basin. The direct precipitation to the 1956 Basin historically infiltrated into the CCR or was pumped to a water treatment system under the current pumping plan. The Cape Fear site operates under a NPDES permit issued by the NCDEQ. Permit number NC0003433, effective February 1, 2019 through June 30, 2023, authorizes seven discharge points (three internal) that flow into the Cape Fear River (Outfalls 001, 005, 007, 008, 008A, 009, and S-05). The 1956 and 1978 Basins do not have working outlet structures. A gate valve is installed in the outlet structure of 1985 basin and dewatering is by mechanical system. The limits and requirements stipulated for these outfalls can be found in the aforementioned permit. In April 2019, NCDEQ promulgated new dam safety requirements and, per the dam safety High Hazard Classification, each CCR basin is now required to pass a full PMP storm event. The Cape Fear Basins are classified as High Hazard by NCDEQ due to the potential for environmental impacts greater than $200,000, if the Basins failed. The PMP event will produce 29.5 inches of rainfall (HMR-51 6-hour, 10 mi2, All -Season PMP Isopluvial Map). Wood evaluated the site for the full PMP rainfall event and results indicated that the 1956 Basin and 1963/1970 Basin both overtop during the design storm event. Spillway designs have been developed for 1956 and 1963/1970 basins to address the requirements of 2019 NCDEQ Dam Safety rules. Also, additional internal storage capacity will be obtained once excavation of the CCR initiates. The 1978 and 1985 Ash Basin have the capacity to contain and release the full PMP storm event. Since the 1956, 1978 and 1985 Ash Basins do not have working outlet structures, per recent NCDEQ guidance these ash basins would require the internal capacity to contain back-to-back full PMP storms. The 1978 and 1985 Ash Basins are currently maintained under Pumping Plans Rev. 0 11 December 2019 12 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan by Duke Energy to assure the design storm inflow is released by pumping the stormwater to the treatment system, followed by release to the Cape Fear River. • Wastewater and Stormwater Management During CCR Excavation Wastewater from the Basins will be pumped, treated (if required) and discharged meeting the NPDES permit discharge requirements, in two phases; the Decanting Phase and the Dewatering phase. In the Decanting phase, free water above the settled CCR layer will be removed from the Basins without the mechanical disturbance of the CCR. In the Dewatering phase interstitial or pore water will be removed from the CCR. The Basin discharges will continue to be in service to meet the NPDES permit discharge requirements as it goes through the two phases of waste water removal. Wastewater from the Basins will be pumped, treated, and discharged through a WMS. WMS at Cape Fear consists of a physical -chemical treatment system designed to meet the requirements of the discharge permit including continuous monitoring for pH and Total Suspended Solids. The Cape Fear site WMS has a designed flow rate of 400 gpm. Following the Decanting phase and as the Closure schedule dictates, the Cape Fear site will advance into the Dewatering phase to remove interstitial water from the Basins. During this phase, additional physical -chemical treatment processes will be added to the wastewater treatment systems as necessary to maintain compliance with the requirements of the discharge permit. During the Dewatering phase, the Cape Fear WMS will have a designed flow rate of 400 gpm. The 1956, 1978 and 1985 Basins are currently maintained under pumping plans by Duke Energy to assure the design storm inflow is released by pumping the stormwater to the treatment system, followed by release to the Cape Fear River. Post -Closure Stormwater Management The post -closure grading is anticipated to provide sheet flow to discharge points flowing to the Cape Fear River with no detention. Up to and including the last phase of closure before the Basin dikes are breached, the Basins will maintain the capacity to contain the required storm size/flows. The concept plans for post -closure grading are based conservatively on 100-year storm events. Appendix C presents the results of the post -closure stormwater management calculations. 8.1 Anticipated Changes in Wastewater and Stormwater Management A WMS has been installed for the closure of the Basins. Afloating intake suction pump and screen (followed by a sump upon sufficient dewatering), has been placed at the location of the lowest elevation within the 1978 and 1985 Ash Basins. The system design, including pump capacity and filter size, are such that the existing NPDES Outfall 008 effluent discharge limits, or other limits as directed by the NCDEQ, will be met throughout the duration of dewatering and closure. Erosion and Sediment Control Plans for different phases of the excavation will be developed as part of the excavation packages for field implementation and formal Erosion and Sediment Control Plan permit submittal. The Basins are NPDES permitted wastewater treatment units. Therefore, only activities that can impact the areas outside the Basins will need to be addressed as part of the Erosion and Sediment Control Plan. However, water quality of discharges from the Basins during excavation may be impacted due to activities within the Basins, and appropriate planning Rev. 0 11 December 2019 13 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. and control measures will need to be implemented. This will be addressed during subsequent stages of the design, and calculations to support the Erosion and Sediment Control Plans will be developed during future stages of the design, which will follow NCDEQ approval of this Closure Plan. In addition, erosion and sediment control measures may be installed and removed in phases as stabilization is achieved. 8.2 Wastewater and Stormwater Permitting Requirements Information on required permits is described in Section 10. 9.0 DESCRIPTION OF FINAL DISPOSITION OF CCR CCR materials in the Basins at the Cape Fear Station will be excavated, processed, and beneficially reused to achieve project goals in accordance with applicable state and federal requirements and beneficial reuse contracts. CCR processing will be done using STAR° Technology, a patented thermal beneficiation process to transform CCR into a high -quality, sustainable product for the concrete industry. An estimate of 5.7 million tons of CCR are currently stored in the Basins at the Cape Fear Station (refer to section 3.1.2 for a detailed discussion and to Appendix Afor quantities). At full production, the STAR° facility is designed to process 400,000 tons of CCR material per year (based on information provided by Duke Energy). Assuming 10-years of processing (2020-2029), this would allow approximately 4 million tons of CCR material to be processed for beneficial re -use, leaving 1.7 million tons which would potentially require handling by another process. In order to meet the CCR removal deadline, Duke Energy will periodically review the progress of the excavation and STAR° processing as it relates to achieving full CCR removal by the required end date of October 1, 2028 for 1956, 1963 and 1970 Ash Basins and October 1, 2029 for the 1978 and 1985 Ponds. Duke Energy will implement a concurrent excavation plan in which the remaining excavated CCR will be transported to an approved landfill facility in order to meet the end date of October 1, 2029 for complete removal. Vegetation encountered or removed during the progression of the work will be managed in accordance with state regulations for handling and disposal. 10.0 APPLICABLE PERMITS FOR CLOSURE Refer to Table 10-1 for detailed information on the potential and applicable permitting/approval needed to implement this Closure Plan. Development of permitting package submittals and/or regulatory approval requests will follow NCDEQ approval of the Closure Plan. 11.0 DESCRIPTION OF POST -CLOSURE MONITORING AND CARE A Post -Closure Care Plan will be developed following NCDEQ approval of the Closure Plan for closure of the CCR Basins located at the Cape Fear Station site. The purpose of the Post -Closure Care Plan will be to provide a description of the inspection, monitoring, and maintenance activities required to be performed throughout the 30-year post -closure care period for the closed CCR Basins at the Cape Fear Station site. The Basins at the Cape Fear Station site are detailed in this Closure Plan as being closed by excavation. Rev. 0 11 December 2019 14 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. The Post -Closure Care Plan will be developed to meet the requirements of N.C.G.S. § 130A- 309.214(a)(4)(k). The items that will be included in the Post -Closure Care Plan for the Cape Fear Station include: • Name, address, phone number, and email address of the responsible office or person • Means and methods of managing affected groundwater and stormwater • Maintenance of the groundwater monitoring systems • Regular inspection and maintenance of the final cover system • Groundwater and surface water monitoring and assessment program • Post -closure inspection checklist to guide post -closure inspections • Description of planned post -closure uses • Financial assurance estimates for post -closure operations and maintenance and remedial action 11.1 Groundwater Monitoring Program This information was submitted to NCDEQ on July 30, 2019 as part of the CAMA Annual Interim Monitoring Report prepared separately for Duke Energy. The CAMA Annual Interim Report is herein incorporated by this reference, but its content was not prepared by Wood. 12.0 PROJECT MILESTONES AND COST ESTIMATES 12.1 Project Schedule On June 30, 2017, Duke Energy selected the Cape Fear Station as an ash beneficiation site as required by N.C.G.S. § 130A-309.216. Excavation of CCR from the Cape Fear Station site for beneficial use will occur over multiple project phases. Activities started in April 2017 and will continue until all CCR is removed from the 1956 and 1963/1970 Basins by 2028, and the 1978 and 1985 Basins by 2029, then continuing until 2029/2030, when final site restoration is completed. A Closure project high-level milestone schedule has been prepared by Duke Energy and the major activities and milestones are provided below: Engineering, Dewatering Ongoing STAR° Unit Construction Complete Q2-2021 STAR' Unit in Operation Q3-2021 Complete CCR Excavation Q1-2029 Site Restoration Q4-2029 12.2 Closure and Post -Closure Cost Estimate Cost estimates for closure and post -closure care of the CCR Basins at the Cape Fear Station were developed by Duke Energy and provided to Wood. These are Class 5 estimates as the detailed and final design has not been developed at this stage of the closure project. Following Rev. 1 2 April 2020 15 Wood Environment & Infrastructure Solutions, Inc. Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan wood. approval of this Closure Plan by NCDEQ and further development of the project plans and engineering designs, the cost estimate will be refined and updated. The cost to complete the closure by excavation is estimated to be $502 million. The cost to perform the 30-year post -closure activities and monitoring is estimated as $23 million. The cost estimates include the following major activities: • Site Infrastructure development, Site Preparation, and Mobilization • Dewatering, Earthwork, and Subgrade Preparation • CCR Excavation • Stormwater Management, Erosion and Sediment Control, and Site Restoration • Engineering Support (Design and CQA) • Closure by Excavation Rectification and Dike Decommissioning • Post -Closure — Groundwater Monitoring • Post -Closure — Operations and Maintenance • Contingency Corrective action costs are included as part of the CAP being prepared separately by SynTerra for Duke Energy and will be submitted to NCDEQ by June 1, 2021. The CAP is herein incorporated by this reference, but its content is not the work product of Wood. Rev. 0 11 December 2019 16 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan 13.0 REFERENCES North Carolina General Assembly, Session Law 2014-122, Coal Ash Management Act, as amended North Carolina Department of Environmental Quality report, "Coal Combustion Residual Impoundment Risk Classification" (2016) North Carolina Department of Environmental Quality, 15A N.C.A.0 02K — North Carolina dam safety rules North Carolina Department of Environmental Quality, 15A N.C.A.C. 02L - North Carolina groundwater rules United States Environmental Protection Agency, Coal Combustion Residuals (CCR) Rule 40 C.F.R. Part 257, subpart D Rev. 0 11 December 2019 17 Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan TABLES Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Table 2-1: CAMA Closure Plan Requirements Summary and Cross Reference Table Duke Energy, Cape Fear Station Corresponding No. Description Closure Plan Section Part II. Provisions for Comprehensive Management of Coal Combustion Residuals § 130A-309.212(a)(4) Closure Plans for all impoundments shall include all of the following: a. Facility and coal combustion residuals surface impoundment — A description of the operation of the site that shall include, at a minimum, all of the following: Site history and history of site operations, including details on the 1 manner in which coal combustion residuals have been stored and 3.1.1 disposed of historically. 2 Estimated volume of material contained in the impoundment. 3.1.2 3 Analysis of the structural integrity of dikes or dams associated with 3.1.3 impoundment. 4 All sources of discharge into the impoundment, including volume and 3.1.4 characteristics of each discharge. 5 Whether the impoundment is lined, and, if so, the composition thereof. 7.1 A summary of all information available concerning the impoundment as 6 a result of inspections and monitoring conducted pursuant to this Part 3.1.6 and otherwise available. b. Site maps, which, at a minimum, illustrate all of the following: All structures associated with the operation of any coal combustion 1 residuals surface impoundment located on the site. For purposes of this 3.2.1 sub -subdivision, the term "site" means the land or waters within the property boundary of the applicable electric generating station. All current and former coal combustion residuals disposal and storage 2 areas on the site, including details concerning coal combustion residuals 3.3 produced historically by the electric generating station and disposed of through transfer to structural fills. 3 The property boundary for the applicable site, including established 3.3 compliance boundaries within the site. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Corresponding No. Description Closure Plan Section 4 All potential receptors within 2,640 feet from established compliance 3 2 2 boundaries. Topographic contour intervals of the site shall be selected to enable an 5 accurate representation of site features and terrain and in most cases 3.3 should be less than 20-foot intervals. Locations of all sanitary landfills permitted pursuant to this Article on the 6 site that are actively receiving waste or are closed, as well as the 3.2.3 established compliance boundaries and components of associated groundwater and surface water monitoring systems. 7 All existing and proposed groundwater monitoring wells associated with 3.3 any coal combustion residuals surface impoundment on the site. All existing and proposed surface water sample collection locations 8 associated with any coal combustion residuals surface impoundment on 3.3 the site. c. The results of a hydrogeologic, geologic, and geotechnical investigation of the site, including, at a minimum, all of the following: 1 A description of the hydrogeology and geology of the site. 4.1 2 A description of the stratigraphy of the geologic units underlying each 4.2 coal combustion residuals surface impoundment located on the site. The saturated hydraulic conductivity for (i) the coal combustion residuals 3 within any coal combustion residuals surface impoundment located on 4.3 the site and (ii) the saturated hydraulic conductivity of any existing liner installed at an impoundment, if any. The geotechnical properties for (i) the coal combustion residuals within any coal combustion residuals surface impoundment located on the site, (ii) the geotechnical properties of any existing liner installed at an 4 impoundment, if any, and (iii) the uppermost identified stratigraphic unit 4.4 underlying the impoundment, including the soil classification based upon the Unified Soil Classification System, in -place moisture content, particle size distribution, Atterberg limits, specific gravity, effective friction angle, maximum dry density, optimum moisture content, and permeability. A chemical analysis of the coal combustion residuals surface 5 impoundment, including water, coal combustion residuals, and coal 4.5 combustion residuals -affected soil. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Corresponding No. Description Closure Plan Section Identification of all substances with concentrations determined to be in excess of the groundwater quality standards for the substance 6 established by Subchapter L of Chapter 2 of Title 15A of the North 4.6 Carolina Administrative Code, including all laboratory results for these analyses. 7 Summary tables of historical records of groundwater sampling results. 4.6 A map that illustrates the potentiometric contours and flow directions for all identified aquifers underlying impoundments (shallow, intermediate, 8 and deep) and the horizontal extent of areas where groundwater quality 4.7 standards established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code for a substance are exceeded. Cross -sections that illustrate the following: the vertical and horizontal extent of the coal combustion residuals within an impoundment; 9 stratigraphy of the geologic units underlying an impoundment; and the 4.8 vertical extent of areas where groundwater quality standards established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code for a substance are exceeded. d. The results of groundwater modeling of the site that shall include, at a minimum, all of the following: An account of the design of the proposed Closure Plan that is based on the site hydrogeologic conceptual model developed and includes (i) predictions on post -closure groundwater elevations and groundwater flow directions and velocities, 1 including the effects on and from the potential receptors and 5.1 (ii) predictions at the compliance boundary for substances with concentrations determined to be in excess of the groundwater quality standards for the substance established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code. Predictions that include the effects on the groundwater chemistry and should describe migration, concentration, mobilization, and fate for substances with concentrations determined to be in excess of the 2 groundwater quality standards for the substance established by 5.2 Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code pre- and post -closure, including the effects on and from potential receptors. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Corresponding No. Description Closure Plan Section A description of the groundwater trend analysis methods used to demonstrate compliance with groundwater quality standards for the substance established by Subchapter L of Chapter 2 of Title 15A of the 3 North Carolina Administrative 5.3 Code and requirements for corrective action of groundwater contamination established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code. e. A description of any plans for beneficial use of the coal combustion residuals in compliance with the requirements of Section .1700 of Subchapter B of Chapter 13 of Title 15A of the North Carolina Administrative Code 6.1 (Requirements for Beneficial Use of Coal Combustion By -Products) and Section .1205 of Subchapter T of Chapter 2 of Title 15A of the North Carolina Administrative Code (Coal Combustion Products Management). f. All engineering drawings, schematics, and specifications for the proposed Closure Plan. If required by Chapter 89C of the General Statutes, engineering 7 1 7 2 design documents should be prepared, signed, and sealed by a professional engineer. g. A description of the construction quality assurance and quality control program to be implemented in conjunction with the Closure Plan, including the 7.3 responsibilities and authorities for monitoring and testing activities, sampling strategies, and reporting requirements. h. A description of the provisions for disposal of wastewater and management of 8 stormwater and the plan for obtaining all required permits. i. A description of the provisions for the final disposition of the coal combustion residuals. If the coal combustion residuals are to be removed, the owner must identify (i) the location and permit number for the coal combustion residuals landfills, industrial landfills, or municipal solid waste landfills in which the coal combustion residuals will be disposed and (ii) in the case where the coal combustion residuals are planned for beneficial use, the location and manner in which the residuals will be temporarily stored. If the coal combustion residuals are to be left in the impoundment, the owner must (i) in the case of closure pursuant to sub -subdivision (a)(1)a. of this section, provide a 9 description of how the ash will be stabilized prior to completion of closure in accordance with closure and post -closure requirements established by Section .1627 of Subchapter B of Chapter 13 of Title 15A of the North Carolina Administrative Code and (ii) in the case of closure pursuant to sub - subdivision (a)(1)b. of this section, provide a description of how the ash will be stabilized pre- and post -closure. If the coal combustion residuals are to be left in the impoundment, the owner must provide an estimate of the volume of coal combustion residuals remaining. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Corresponding No. Description Closure Plan Section j. A list of all permits that will need to be acquired or modified to complete 10 closure activities. k. A description of the plan for post -closure monitoring and care for an impoundment for a minimum of 30 years. The length of the post -closure care period may be (i) proposed to be decreased or the frequency and parameter list modified if the owner demonstrates that the reduced period or modifications are sufficient to protect public health, safety, and welfare; the environment; and natural resources and (ii) increased by the Department at the end of the post -closure monitoring and care period if there are statistically significant increasing groundwater quality trends or if contaminant concentrations have not decreased to a level protective of public health, 11 safety, and welfare; the environment; and natural resources. If the owner determines that the post -closure care monitoring and care period is no longer needed and the Department agrees, the owner shall provide a certification, signed, and sealed by a professional engineer, verifying that post -closure monitoring and care has been completed in accordance with the post -closure plan. If required by Chapter 89C of the General Statutes, the proposed plan for post -closure monitoring and care should be signed and sealed by a professional engineer. The plan shall include, at a minimum, all of the following: 1 A demonstration of the long-term control of all Ieachate, affected 11.1 groundwater, and stormwater. A description of a groundwater monitoring program that includes (i) post - closure groundwater monitoring, including parameters to be sampled 2 and sampling schedules; (ii) any additional monitoring well installations, 11.2 including a map with the proposed locations and well construction details; and (iii) the actions proposed to mitigate statistically significant increasing groundwater quality trends. I. An estimate of the milestone dates for all activities related to closure and 12.1 post -closure. m. Projected costs of assessment, corrective action, closure, and post -closure 12.2 care for each coal combustion residuals surface impoundment. n. A description of the anticipated future use of the site and the necessity for the implementation of institutional controls following closure, including property 6.2 use restrictions, and requirements for recordation of notices documenting the presence of contamination, if applicable, or historical site use. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Corresponding No. Description Closure Plan Section § 130A-309.212(b)(3) No later than 60 days after receipt of a proposed Closure Plan, the Department shall conduct a public meeting in the county or counties proposed Closure Plan and alternatives to the public. § 130A-309.212(d) Within 30 days of its approval of a Coal Combustion Residuals Surface Impoundment Closure Plan, the Department shall submit the Closure Plan to the Coal Ash Management Commission. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Table 4-1: Summary of Typical Material Properties Duke Energy, Cape Fear Station Properties CCR within the Basins Foundation Soil (Residual) below the CCR Basins Fill Soil within the Embankment Dikes Foundation Soil (Residual) below the Embankment Dikes Partially Weathered Rock (PWR) Soil Type Sand with silt (SP) to Silty Sand (SM) Predominantly Bottom Ash, Silt/Sandy Silt (ML) - Predominantly Fly Ash USCS Classification- CH, CL, ML, SC, SM, SP, GC, and GW USCS Classification- CH, CL, ML, SC, SM, and GW USCS Classification- CL, ML, SC, SM, SP, SW and GP Sampled as ML and CL with gravel and rock fragments Color Light Gray to Dark Gray and Black Brown, Red -Brown, Tan, and Gray Tan, Orange, Gray and Black Brown, Gray, and Tan Red, brown, black, and gray Plasticity Predominantly Non Plastic Non Plastic to Plastic Non Plastic to Plastic Non Plastic to Slightly Plastic ** Liquid Limit Predominantly Non Plastic NP - 83 NP - 68 20 - 47 40* Plasticity Index Predominantly Non Plastic NP-50 NP - 42 2 - 25 21* Representative Range Geometric Mean Representative Range Geometric Mean Representative Range Natural Moisture Content (%) 2% - 62% 33% 14% - 59% 28% 14% - 25% 11% - 78% 11%* Fines Content 22% - 76% 52% 7% - 79% 39% 40% - 88% 6%- 95% 78%* Clay Content 1% - 10% 4% 4% - 56% 16% 12% - 55% 4%- 48% 29%* Blow Count - Uncorrected N Value (bpf) WOR - 27 4 WOH - 50 12 3 - 34 1- 70 >50/0.5* Moist Unit Weight 89 - 105 pcf 95 pcf 111- 139 pcf 126 pcf 116 - 138 pcf 111- 118 pcf ** Dry Unit Weight 55 - 75 pcf 66 pcf 92 - 114 pcf 103 pcf 103 - 123 pcf 92 - 135 pcf ** Specific Gravity 2.2 - 2.4 2.3 2.7 * ** ** ** Horizontal Hydraulic Conductivity (cm/sec) 3.0E-06 - 7.9E-03 3.10E-04 ** ** ** ** ** Vertical Hydraulic Conductivity (cm/sec) 1.4E-04 I * 8.4E-07 - 5.2E-05 4.50E-06 I 9.4E-04 - 3.5E-04 ** ** Notes: No boring or laboratory information obtained prior to 2006 was included in the table above. For additional information, see attached Appendix Outlier values were not included in the table above. For additional laboratory testing information, see attached Appendix NP: Non Plastic pcf: Pounds per cubic foot (Ib/ft) bpf: blows per foot WOR: Weight of rod WOH: Weight of hammer *Only one lab test available **No lab testing data was available Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Table 10-1: Regulatory Permits, Approvals, or Requirements for Basin Closure by Excavation Duke Energy, Cape Fear Station Permit/Approval Existing Type of Regulatory General Permit Regulating Permit No. Approval Comments Name or Subject Agency (if Mechanism or Not applicable) Required Air Quality NCDEQ Not Anticipated Chatham Building Permit Not Anticipated County Modification or abandonment of CAMA program CAMA Monitoring Written NCDEQ DWR monitoring wells NCDEQ Plan approval require the approval of the Division of Water Resources (DWR) CCR Impoundment US EPA CCR Required postings Self -Regulating Closure Rule to Public Record Maintain CCR GW monitoring CCR Impoundment US EPA CCR network and Self -Regulating Monitoring Network Rule requirements as stated in 257.90 - 257.98 Clean Water Act 401 Not Anticipated Clean Water Act 404 Not Anticipated Cutting Trees Not Anticipated Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Permitting is required to modify CHATH-075 or abandon wells CHATH-076 and Certificate of instrumentation on Dam Safety NCDEQ CHATH-077 Approval to Modify regulatory dams CHATH-078 through the CHATH-079 Division of Energy, Mineral, and Land Resources (DEMLR) Ash Basin Dam - Permitting is required to modify the dam in CHATH-075 accordance with CHATH-076 the Dam Safety Certificate of Law of 1967, 15A Dam Safety NCDEQ CHATH-077 Approval to Modify NCAS 02K.0201 CHATH-078 (b)(2); an CHATH-079 application must be filed with the Division of Energy, Mineral, and Land Resources (DEMLR) DOT - General Not Anticipated Driveway Permit NCDOT Not Anticipated Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan No land disturbance activities outside of the ash basin are NCDEQ and anticipated. In Erosion and Sediment Chatham Not Anticipated conformance with Control (E&SC) County 15A NCAC 04, no E&SC Permit is anticipated to be required from Land Quality. Removal from or import of material could be restricted dependent on the Fire Ants Restriction not likely potential for fire ants and geographic regions involved No development activities are anticipated within FEMA mapped Floodplain Chatham Not Anticipated Special Flood Development County Hazard Areas for the Flood Insurance Rate Maps Multi -State Not Anticipated Agreement NPDES (National Pollution Discharge NCDEQ NC0003433 Not Anticipated Elimination System) Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Removal from or import of vegetated material could be restricted Noxious Weeds Not Anticipated dependent on the vegetation and geographic regions involved Construction activities adjacent Railroad Easement, to tracks/ballast or Access, or Crossing Not Anticipated a new railroad Permit crossing require an agreement or permit In accordance with the federal Water SPCC (Spill Prevention Pollution Control Control and Act (Clean Water NCDEQ Not Anticipated Countermeasure) Act) of 1974, Title Plan 40, Code of Federal Regulations, Part 112. Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan Federal and/or state regulations may apply including agency Threatened or consultation and Endangered Species: performing site - Candidate specific surveys Conservation within the proper Agreement Avian survey period (e.g., Protection Plan(s) NCDEQ And EPA Not Anticipated flowering period Bird and Bat for listed plant) to Conservation determine if Strategies Eagle Threatened or Conservation Plan Endangered Eagle Take Permit Species or their habitat exist within the limits of disturbance Solid Waste Site No new CCR NCDEQ Not Anticipated Suitability Landfill planned Solid Waste Permit to No new CCR NCDEQ Not Anticipated Construct Landfill planned Solid Waste Permit to No new CCR NCDEQ Not Anticipated Operate Landfill planned County Approval - Chatham No new CCR Not Anticipated zoning County Landfill planned Wood Environment & Infrastructure Solutions, Inc. wood Duke Energy Coal Combustion Residuals Management Program Cape Fear Station Basin Closure Plan FIGURES 101 ..:sills; low rlk'- `V DAM ID: Y - . CHATH-075 APPROXIMATE �P. ., 1956 PROPERTY LIN •:� � BASIN ;F'` ..r.i # , ' ti '' MAIN GATE„ •r,., " %±-� r* r • r' . , r - ' W - _ LL 115 Kv r , IF f ` SUBSTATION r . ��j. ,may G-t a • r .+•j• Ap SUBSTATION- .l 1985 BASIN .. * fr 'rR l - ' - y - 1 � r , • - • 1 .IL. �'�• r • � - � r t r 1n . 7 ' PYRITE AREA ' FORMER WA T R' * �,,,• _ t ,r,,,TREATMENT AREA • �� ` PROPOSED STAR 1978 ��" -\ ' `"� UNIT AREA - � � BASIN Z DAM ID: s .* DAM I D: 1 _ ' CHATH-076 r DAM ID. - I ` CHATH-078 - EXISTING IL a 1963/70 PARKING/LAYDOWN • _ I R Z. ' + I AREA + I BASINmom , - x t. r WETLANDS ru EXISTING OUTLET _ ' - 1• J' STRUCTURE .1'! ; • , .a 1i S' 'T �• `` . ' r ' - :- x _ • 1 L_ _ _ R r 1 . • . . . * • it �-' t �1 fJ_1 ./..� �,f a► !' OA A _ y Q � R +�� r \� iR . � - M rYiK��. a f �.l''i i r; •` "i +_ * •tip DAM ID: F CHATH-077 ' - - - IL,. _ f '`� "►� , - -"� NPDES OUTFALL 007 • ,�� .� 1. `�('R L * R ��'t i • ` • • '.� - - ' .. 41 ' +y •IoI• b a A ft f�r rn 3 U 0 0 Of U x Ld 0 0 0 U x Ld 00 rn C 0 0- 00 00 0 00 0 r- L 0 LL a 0 U a L Ld a� 0 / 0 a U / i / / 0 M O� r 0 .z N I E Lo Q U 0 0 J c 0 0 0 U x Lij Ln 00 0 m 'all 2 3 4 5 6 7 s FIGURE 1-2 REV. o0 U{\\11 I I \ \\\\\ I j \\ \ •s� \\ ��,FP \ `° \ I \ I/ (✓ / / ��o� /�/// LEGEND � �� r a� a EXISTING MAJOR CONTOURS (D CP&L BORINGS - TYPE IV \ \ ° \� \100YR FP EXISTING MINOR CONTOURS CP&L PIEZOMETERS WOOD LINE AMEC BORINGS xxxxx—x—x— FENCE LINE GEOSYNTEC BORINGS \sd b 0 0 i \\ \ // F, /// o — WATER SURFACE GEOSYNTEC CPTS & SCPTS DITCH LINE MACTEC BORINGS y ( 001 Il PAVED PATH MACTEC CPTS ----------- UNPAVED PATH WITHERS & RA VENAL BORINGS -�' I� I � • ' WETLANDS WITHERS &RAVENAL CPTS 1956\= \ APPROXIMATE LIMIT OF WASTEBASIN 100YR FP ZONE AE FLOODPLAIN LIMIT 9 EXITING MONITORING WELL CP&L BORINGS - TYPE 111 � 13 / II // J \ /// \�\ / / \ NOTES: \_ / 11 / / 1 •\ // 11\ \ ( (� 1. WELL AND BORING IDENTIFICATION IS SHOWN ON CLOSURE PLAN DRAWINGS IN APPENDIX D. 00, f �� ` ' \I __ ,\ rj \ � l APPROXIMATE PROPERTY LINE , ��H . _ / o I 11 ,8>s �, \ \s o — �A ( \ 1 �`� �, =� ,o 03 Iv< 2\� /- - /7o f C . I I� I I J / I 100 V lJll/ • ,, � v � Vl 1� � v v � �, y vv� v / �\ 1 III // � / I (� \. \ �, 1 \��\\ C \ 1 S Illl \� \I"• /��' 1985 BASIN 2z jfo, 115 Kv / \ J ((I I II I I IIJ III \c SUBSTATION \ I J ll ( 1 j\1\\ ll (I/ 1 / I(I• \-os�\ w\ \�foo\` � I•- � \ \ \ \ \ /�//J/ • l \ � I 1 —III I l II III \\ \\\\�f ,� \� � ° �i \ � � \ -/ I� \\�\ �_ � �� -. �\I \ \ �1 / — •' \ \\ \ \\ \ . \ s \ \ 19 _ i � ------ I I I � III �� \ r _ � \ \\ �\�� •e''^ � \\�\` ` � / � � � � � //'� / I I EXISTING OUTLET \ / / / \ \\ \ )� i ,�S \\\ > ^co STRUCTURE I I (I1978 \ 1963/190 BASIN 71 i; \ 1 ,� \ \ ^lG \ \ { f o D I \I II / /r--� \� ` / I BASIN \ \� \ ( / / J \ \ - / / �' (,90 \ I /�}� / �f I • I -I�� \ ' —��i� ; �O /��/ 1 I I 1�/,/ I I I \ \ ( /��- //ice% �'• • �\ \ \ / ,\ \\ \\ i /�%_-i�j J ` / \ /` I } �' 1 J //%--\� J ` \ \) • Jam/ /.-�/Lc„�� \ lL` / /��/\\\j/ / //I EXISTING LAYDOWN ( I AREA I � � ( / � ( // / - o1 % \ Z \. o� o `-✓„�® I � / / / PROPOSED / \ / \ � WETLANDS C (( (TYP.) \ IIII ( / I ( I /STAR UNIT ) -\ 1 } \> / - �s\I (Il \I ( I I0 / —s f J / / I \ I IIII \ ��I Ig395 II I '' / wr-ss-o�� / l o a ./( \//\\ EXISTING 0 ouLEr`(/IL0) STRUCTURES er / `\� / � \\ � � \� 1► III //i � \1U \I\\ o�—�_/-- _\I j �. ^}- \ ��\\� \ - - - - - - - - - \ -\ 200 0 200 400 FT I \\ L \ //�� ! �\ � � _ / � //// / \ \\\\\ \ \\\\ \ / \ \ / ' / O / / 9 `\\\ I// \ \ \\\\ \�/ /� \\ i/ / / \ ___�` // \ \� \ \ _ I Ill1/l !� �\ 11 1 �1 \ V 1, \\\//�_\\ \ ' / � G \ \ \ \ �\ ,\\\ /- - - I l 111 \ \\\ U //�— \ 111 TITLE COAL COMBUSTION RESIDUALS SURFACE do \\ '�\ IMPOUNDMENT CLOSURE PLAN woo CAPE FEAR STEAM STATION F — l~II \ III(I(I /I Environment &Infrastructure Solutions F \ \ , I (IIIIII IJ` / - � �\� \5 � \ \ • • • - 4021 STIRRUP CREEK DRIVE, SUITE 100 DURHAM NC27703 OVERALL EXISTING CONDITIONS PLAN / / \ / \ \ � I I11111111�I I�I\\\\ —175_ +! \ • i \ ` - \ '� \ II \ \ _ \\ III IIIIII((/// TEL: (919) 381-9900 F�ICENSURE:901 FOR NC EEG: URE: ISSUED FOR REVIEW o. \ 1 \ \ NC 3EOLOGY:C-247 SEAL SCALE: AS SHOWN DES: JL I // \\ \ �/ IIII \\ \• DUKE DWG TYPE: DWG DFTR VD \ / \ \ \\ j \ \\ - - - / I \ / % I7N It / / \ \\ \ / \ \\1 - - - - \ `/ 1 \ \\ f / '/ JOB NO: 7810181088 CHKD: AP s ENERGY® DATE: 12/10/2019 ENGR: WAW APPD: \,/�7 // /l�<< FILENAME: CFR_005C.DWG CRK NOT FOR DWG SIZE DRAWING NO. REVISION ONSTRUCTIO ANSID 22"x34" FIGURE 1-2 REV DATE I JOB NO. PROJECT TYPE DES DFTR CHKD ENGR APPD DESCRIPTION TENTHS 10 20 30 4 5 6 7 8 9 10 INCHES 1 2 3