The URL can be used to link to this page

Home My WebLink AboutClosure Documentation_20200313DUKE Paul Draovitch Senior Vice President ENERGY Environmental, Health & Safety ® RECEIVED and Operations Support 526 S. Church Street MAR 17 20�� Mail Code: EC3XP Charlotte, NC 28202 (980) 373-0408 NC DEQUDWR March 11, 2020 Central office Rick Bolich, L.G. North Carolina Department of Environmental Quality Division of Water Resources 512 North Salisbury Street Raleigh, NC 27699 Edward F. Mussler III, P.E. North Carolina Department of Environmental Quality Division of Waste Management 217 W Jones Street Raleigh, NC 27603 C Dept of Environmev Quality N t4NR i 3 2020 galeigb�egional Office Subject: Documentation of Compliance with the Coal Ash Management Act of 2014, Session Law 2014-122, Sections 3.(b), 3.(c)(1) and 3.(c)(2), Coal Ash Impoundment Excavation and Closure, Riverbend Steam Station — Ash Basin 1 and Ash Basin 2 Dear Messrs. Bolich and Mussler: This letter responds to the department's letter of December 6, 2019, requesting additional information around closure of the CCR surface impoundments at Duke Energy's Riverbend Steam Station (Riverbend). As a preliminary matter, consistent with Duke Energy's earlier position, with one exception (discussed below), the high -priority sites, including Riverbend, are strictly governed by Sections 3.(b) and 3.(c) of CAMA. Accordingly, Section 3.(a) of CAMA, which contains, among other provisions, § 130A-309.213 (impoundment prioritization) and § 130A-309.214 (impoundment closure), is not generally applicable to these sites. The "notwithstanding" language in the first sentence of Section 3.(b) makes this clear.' The one exception is the applicability of § 130A-309.211, which addresses corrective action to restore groundwater quality.2 The reason for its applicability to the high -priority sites is explained by the fact that § 130A-309.211 is specifically referenced in CAMA Section 3.(c)(3). (Indeed, it is the only provision in CAMA Section 3.(a) that Sections 3.(b) and 3.(c) reference.) This notwithstanding, in recognition of the importance of providing the department with information it deems relevant to basin closure, Duke Energy provides the following response: 1 North Carolina General Statutes (N.C.G.S.) Sections 13oA-309.211 and 13oA-309.212 were codified as §§ 13oA-309.213 and 13oA-309.214, respectively. 2 N.C.G.S. § 3.(c)(3) refers to "corrective action to restore groundwater quality ... as provided in G.S.13oA- 309-204." The General Assembly probably intended to reference N.C.G.S. § 130A-309-204, which was subsequently codified as N.C.G.S. § 13oA-309-211. This section was subsequently correctly referenced as N.C.G.S. § 13oA-309-211 in § 3.(b) of H.B. 630. Summary of closure activities to date and those planned in the context of proiect milestones MILESTONE STATUS Submit Excavation Plan to NCDEQ Completed November 13, 2014 Complete Comprehensive Engineering Completed November 30, review 2014 Excavation Plan Acknowledgement from NCDEQ Completed February 2, 2015 Receive Industrial Stormwater Permit Completed May 15, 2015 Completed May 21, Commence Work — Ash Removal 2015 Submit Updated Excavation Plan to NCDEQ Completed November 13, 2015 Submit Updated Excavation Plan to NCDEQ Completed December 21, 2016 Submit Updated Excavation Plan to NCDEQ Completed December 1, 2017 Submit Final Excavation Plan to NCDEQ Completed December 11, 2018 Eliminate Stormwater Discharge into Completed December 14, Impoundments 2018 Impoundments Closed Pursuant to Sections 3.(b) Completed March 16, 2019 and 3.(c) of CAMA As -built drawings and schematics along with the results of anv engineering evaluations and analyses for the closed impoundments The "as -built" condition of the Riverbend CCR surface impoundments following excavation of all CCR materials is illustrated in Attachment 1, Bottom of Ash Excavation Grades. Engineering and analysis was provided in the Ash Removal Verification Report submitted to the department on April 18, 2019. Final Plans for management of wastewater and stormwater Upon the completion of CCR removal from the Riverbend CCR impoundments, wastewater strearns ceased and the NPDES Wastewater Outfall 002 was decommissioned. The site is in the final phases of dam decommissioning and grading in general accordance with Attachment 2, Final Grading Plans. This final grading plan designates sheet flow of all stol-inwater. List of all State or Federal permits obtained or anticipated for impoundment closure MEDIA1 DATE COMMENTS NPDES Industrial NCDEQ issued the ISW permit Stormwater (ISW) May 15, 2015 May 15, 2015. SPPP Permit implementation date Water was November 15, 2015. NPDES Wastewater Q1 2016 Permit became effective December Permit — Major (Modified by SOC in 1, 2016. Modification Q4 2016) There are no identified Jurisdictional Wetland and Stream Impacts / 404 N/A jurisdictional Permitting wetland stream impacts. and 401 W C Intermediate Dam Submitted May 31, 2016. Decommissioning June 16, 2016 Received approval June 16, 2016. Request Approval Decommissioning completed March 13, 2017. Primary Dam Submitted May 8, 2017. Modification Request August 3, 2017 Received approval August 3, 2017. Dam Safety Approval Modification completed March 3, 2018. Resubmitted May 29, 2018. Primary and Secondary Dam Received approval June 7, 2018. Decommissioning June 7, 2018 Decommissioning is currently in Request Approval progress. Mine reclamation Waste Individual Structural October 15, 2015 owner/operator obtained Fill Permit (Permit to Operate) an Individual Structural Fill Permit pursuant to N.C.G.S. § 130A- 309.219. Original permit received Duke Energy Water Conveyance August 2, 2016 April 7, 2016. Amended permit Lake Services Permit for revised quantities received August 2, 2016. Description of the Post -Closure Monitoring and Care Plan; proposed Final Monitoring Plan Upon completion of closure and final grading at Riverbend, post -closure monitoring and care will be conducted in accordance with the June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan. This plan was prepared in accordance with N.C.G.S. § 130A-309.212(4)(k) and is included in this submittal as Attachment 3. Groundwater monitoring will continue to be conducted according to the March 20, 2019 Interim Monitoring Plan (IMP) until the 2020 IMP is approved by NCDEQ. The current Riverbend IMP is included in this submittal as Attachment 4. The IMP will be effective at Riverbend until a site Corrective Action Plan with an associated Effectiveness Monitoring Plan (EMP) is approved by NCDEQ. Upon the completion of groundwater corrective action, effectiveness groundwater monitoring will be replaced with post -closure groundwater monitoring. Updated cost estimates for closure andpost-closure operation • Basin closure (including dam stability/emergent projects) ;::� $412.2 million • EHS-GW/Post-Closure Maintenance - $21.5 million • Total Compliance Cost --zf $433.7 million Duke Energy remains committed to safely and permanently closing ash basins in ways that continue to protect people and the environment and welcomes the opportunity to work constructively with the department to move forward. Sincer Dy, Pov Senior Vice Enviromnent.al, Health & Safety and Operations Support Attachments: • Attachment 1, Riverbend Bottom of Ash Excavation Grades • Attachment 2, Riverbend Final Grading Plan • Attachment 3, Riverbend Post -Closure Operations Maintenance and Monitoring Plan • Attachment 4, Riverbend Interim Monitoring Plan Optimization Attachment 1 Riverbend Bottom of Ash Excavation Grades RECEIVED MAR 17 2020 NC DEQ/DWR Central Office a m .004 1 4 a� s - i F4 g o fD sp Ool i pi W 9 0 .40 naiY_-. - E5555, F i JAJ Ilse .4 a ,,1 f I Attachment 2 Riverbend Final Grading Plan RECEIVED MAR 17 ZQZB NC DEQIDVVR Central Office __ _ - I .019 I 0 W bey 0 W a § O oN rn U w ° 5 ¢ g o m x za��m p i�+g� ° O � .} a y � �S BYE � 0) z z S VI � F IN i µ I 1 .020 1 0 0 a — g a z � O to I a p W o aB s w N > z LU tl m a o Y w QW w a & ^ b y cm W S f a m u w .021 I ZZO' 133HS 33S o 3NIIHOLVW ff s O ;e - a H o OR. oa�z3 w I I ph w o g s'�Zy4y O w I & �L W $ w o r wo ` P LL - LL� O a J?P bs` M. .022 — 0 e I- 0 N LAW; 9 YL Lu 's 0 N LAW; 9 YL Lu 's Attachment 3 Riverbend Post -Closure Operations Maintenance and Monitoring Plan RECEIVED MAR 17 2020 NC DEQ/DWR Centre! Office POST -CLOSURE OPERATIONS MAINTENANCE AND MONITORING (OM&M) PLAN RIVERBEND ASH BASINS DUKE ENERGY - RIVERBEND STEAM STATION MT. HOLLY, NORTH CAROLINA REVISION 0 Prepared for DUKE ENERGY. Duke Energy 550 South Tryon Street Charlotte, North Carolina 28202 June 30, 2016 anlec ■ Foster whwier Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 TABLE OF CONTENTS 1. INTRODUCTION...................................................................................................................................1 1.1 Project Information ........................................................................................................................1 2. DESCRIPTION OF CLOSURE COMPONENTS...................................................................................1 2.1 Compacted Fill.............................................................................................................................. 2 2.2 Geotextiles.................................................................................................................................... 2 2.3 Riprap and Aggregate................................................................................................................... 2 2.4 Final Soil Layer.............................................................................................................................. 2 2.5 Vegetative Ground Cover.............................................................................................................. 3 2.6 Stormwater Management System................................................................................................. 3 3. POST -CLOSURE OM&M PLAN........................................................................................................... 3 3.1 Monitoring Activities...................................................................................................................... 3 3.1.1 Groundwater Monitoring............................................................................................................4 3.1.2 Surface Water Monitoring..........................................................................................................4 3.1.3 Reporting................................................................................................................................... 4 3.1.4 Modifying Monitoring Requirements..........................................................................................5 3.2 Maintenance Activities.................................................................................................................. 5 3.2.1 Post -Closure Stormwater Maintenance.................................................................................... 5 3.2.2 Post -Closure Erosion and Sediment Control Maintenance....................................................... 5 3.2.3 Post -Closure Vegetation Maintenance......................................................................................6 3.3 Facility ContactInformation........................................................................................................... 7 3.4 Post -Closure Planned Use............................................................................................................ 8 3.5 Certification................................................................................................................................... 8 List of Appendices AppendixA Example Post -Closure Monitoring Form If amen foster wheeler i Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 1. INTRODUCTION This Post -Closure Operations Maintenance and Monitoring (OM&M) Plan is being submitted as part of the Riverbend Steam Station Site Analysis and Removal Plan (Removal Plan) which has been prepared to address removing coal combustion residuals (CCRs) from the site and to comply with the regulatory requirements of the North Carolina Coal Ash Management Act (CAMA) for closure of ash basins / surface impoundments. The information contained in this plan will be used to assist Duke Energy Carolinas, LLC (Duke) in the closure of inactive coal ash impoundments and the maintenance and monitoring required during the post -closure care period. 1.1 Project Information Duke intends to decommission and remove the CCR facilities, specifically the Primary and Secondary Ash Basins, Dry Ash Stack and Cinder Pit Storage Area, on the property of the retired Riverbend Steam Station. The primary objective of the Removal Plan is to remove CCR materials from the site, breach the existing dams that form the ash basins, and to establish final grades to promote drainage. The CCR materials at the Riverbend Steam Station will be excavated and removed from the site using conventional excavation equipment and transported using over -the -road trucks and, eventually, transition to railcar after the initial phases of the project. Upon establishing final grades, the site will be seeded to establish a vegetative ground cover per approved grading plan drawings and specifications. In addition to establishing vegetative ground cover, relatively gentle slopes will be established during final grading to control runoff velocities. The final long term disposition of the site has not been determined at this time. The short term disposition of the site will be grading the site to drain, establishing the vegetative cover, and maintaining the site in an undeveloped state. 2. DESCRIPTION OF CLOSURE COMPONENTS Decommissioning of the CCR facilities at the Riverbend Steam Station includes breaching the Primary Ash Basin Dam (State ID GASTO-097), the Secondary Ash Basin Dam (State ID GASTO-098), and the Intermediate Dam (State ID GASTO-099). Soil removed from the dams during excavation and grading activities will be stockpiled and, if suitable, used as fill material to achieve final grades within the excavation limits of the former CCR facilities. The proposed closure components are described in the following sections of this report. The various components to be used for the closure of the CCR facilities will consist of the following: • Compacted fill (including soil materials excavated from onsite) placed on subgrades • Geotextiles placed according to decommissioning plan specifications • Riprap and aggregate placed according to decommissioning plan specifications • Final soil layer placed on final grades �1 � Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 • Vegetative ground cover including seed, mulch, and soil amendments applied to prepared soil surfaces on final grades A temporary soil layer and vegetation will be installed and maintained during the construction work to manage erosion and sedimentation. Riprap and geotextiles will be utilized in temporary and permanent stormwater management structures. Aggregate will be utilized for site access and temporary haul roads during the construction work. Stormwater management structures will collect surface water runoff according to the decommissioning plan. The final ground cover for areas disturbed during the dam decommissioning and CCR removal activities will be vegetated and maintained with grasses. 2.1 Compacted Fill Compacted fill to be used in the closure of the CCR facilities at Riverbend Steam Station will be soil from excavation or grading activities. Soil materials used for compacted fill may classify as sand (SW, SP, SM, SC), silt (ML or MH), or clay (CL or CH) under the unified soil classification system. Note that any fill classified as peat (PT) or organic silt or clay (OL or OH) shall not be accepted as compacted fill for the project. 2.2 Geotextiles Woven and non -woven geotextile fabrics to be used in the closure of the CCR facilities at Riverbend Steam Station will consist of polypropylene material resistant to biological degradation and naturally occurring chemicals, alkalis, and acids. Applicable ASTM and AASHTO standards for geotextile properties as well as delivery, storage, and handling requirements are provided in the specifications included with the decommissioning plan. 2.3 Riprap and Aggregate Riprap to be used in the closure of the CCR facilities at Riverbend Steam Station may consist of imported Class A, B, C and Class 1 and 2 rock from a commercial quarry meeting the requirements of Section 1042 RIP RAP Materials in the NCDOT "Standard Specifications for Roads and Structures," 2012 Edition and additional requirements provided in the specifications included with the decommissioning plan. Note that demolished concrete shall not be accepted as imported riprap for the project. 2.4 Final Soil Layer The final soil layer to be used in the closure of the CCR facilities at Riverbend Steam Station will consist of topsoil stripped from onsite during excavation or grading activities. Topsoil will be removed from excavation and grading areas and stockpiled for reuse after final grades are established at the former CCR facilities. The topsoil shall be spread 3 inches thick on final grades prior to application of seed, mulch, and soil amendments and will be capable of sustaining vegetation to prevent erosion. 2 Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 In the event that adequate quantities of stockpiled topsoil are not available to cover graded areas, soil preparation will be implemented according to the soil testing report included in the technical specification of the decommissioning plan. Finished grade surfaces will be prepared to promote positive drainage and support a grass vegetative cover. 2.5 Vegetative Ground Cover The vegetative ground cover to be used in the closure of the CCR facilities at Riverbend Steam Station will consist of permanent and temporary seed mixes, nurse crops, mulch, and soil amendments. Unless directly superseded by the plans and specifications, preparation of subgrade and seeding shall be performed in accordance with the requirements of the North Carolina Department of Environmental Quality (NCDEQ) "Erosion and Sediment Control Planning and Design Manual' dated May 2013, or latest revision. Prior to seeding, soil surfaces receiving seed shall be scarified to a depth of two to four inches to aid seed germination and reduce loss of seed during stormwater runoff events. However, the vegetative soil layer will not be subjected to compaction requirements. 2.6 Stormwater Management System The proposed closure of the CCR facilities at the Riverbend Steam Station is designed with a network of stormwater conveyances accounting for ash basin dam decommissioning, CCR removal, and final closure conditions. Stormwater that does not come in contact with CCR materials during the closure will be treated as non -contact water. Non -contact water will be managed separately from water within the Ash Basins or that contacts CCR materials. Non - contact water may be used for dust control or other operational purposes during construction. Upon final closure, stormwater will be directed across vegetated finished grades and into riprap energy dissipaters before discharging into stormwater culverts and/or wetland areas that ultimately discharge to the Catawba River and Mountain Island Lake. Final grading plans and details illustrating the stormwater management system are provided in the decommissioning plan drawings. 3. POST -CLOSURE OM&M PLAN The Post -Closure OM&M Plan outlines the operations, monitoring, and maintenance activities required to be performed during the post -closure care period. During the post -closure period, the re -graded and vegetated areas of the former CCR facilities at the Riverbend Steam Station will be monitored and maintained to sustain their integrity and effectiveness until permanent vegetation is established. 3.1 Monitoring Activities Post -closure monitoring events will be conducted quarterly for the first two years and semi- annually thereafter until permanent vegetation is established on the former CCR facilities. Post - closure monitoring will include a review of the following: 3 Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 • The condition of site security features such as gates and/or fencing • Evidence of erosion, settlement, ruts, burrows and/or other disturbances within the closure areas • Type and quality of vegetation within the closure areas • Evidence of erosion and integrity of stormwater conveyance features Example forms that may be used to document the monitoring events are included in Appendix A. The proposed grading profiles and final grades showing the limits of disturbance and stormwater features are presented in the decommissioning plan. As -built drawings will be prepared after the dam breach and following completion of the final grades on the former CCR facilities. The as -built drawings will be used to assist with post -closure monitoring. Completed post -closure forms will be maintained in the facility operating record. 3.1.1 Groundwater Monitoring Post -closure groundwater monitoring requirements will be established in the Groundwater Monitoring Plan, and submitted under separate cover. The Comprehensive Site Assessment (CSA) Report (HDR, August 2015a) provides an interim groundwater monitoring plan to bridge the gap between completion of CSA Report activities and implementation of the pending Groundwater Monitoring Plan and Corrective Action Plan (CAP). Two comprehensive sampling events and two background -only sampling events were conducted in 2015. There have been two comprehensive sampling events so far in 2016. The proposed constituents and parameters for the interim groundwater monitoring plan are presented in Table 16-1 of the CSA Report, and the proposed sampling locations are presented in Table 16-2 of the CSA Report. The interim groundwater monitoring plan includes sampling background wells during the additional interim groundwater sampling event in 2015. 3.1.2 Surface Water Monitoring Post -closure surface water monitoring will be consistent with the NPDES permits for wastewater discharges (Permit NC0004961) and stormwater discharges (Permit NCS000549) for the Riverbend Steam Station. The discharge permits should be consulted for a detailed description of the parameters and frequency of surface water monitoring required at the site. Following completion of the closure activities at the Riverbend Steam Station, wastewater and stormwater discharge NPDES permits will require modification to reflect the discontinuation of certain discharges. Discontinued discharges include flow from the ash basin and dewatering liquids, as well as, several stormwater pipes and outfalls that will be removed during construction. 3.1.3 Reporting In addition to the forms, reporting, and record keeping that will be maintained as part of the groundwater and surface water monitoring plans, the various notifications, reports, plans, and amec foster wheeler 4 Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 amendments associated with closure and post -closure of the CCR facilities will be placed onto Duke's CCR web site. 3.1.4 Modifying Monitoring Requirements A request can be made any time during the post -closure care period to reduce the requirements for groundwater monitoring provided that sufficient justification exists for the periodic reduction. The request will explain the reason for reducing monitoring with justification, and be submitted to NCDEQ for regulatory approval. 3.2 Maintenance Activities Maintenance activities will be conducted as soon as practical to address items of concern identified during monitoring events. Maintenance activities will be performed at the frequencies defined herein and are anticipated to include the following: • Localized placement of fill to prevent ponding of water caused by settlement, erosion, ruts, burrows and/or other disturbances • Mowing vegetation • Vegetative cover shall be amended and fertilized as needed to maintain healthy vegetation • Repair of stormwater conveyance measures 3.2.1 Post -Closure Stormwater Maintenance Post -closure operations of the former CCR facilities at the Riverbend Steam Station shall not cause the discharge of a non -point source of pollution to waters of the United States, including wetlands, that violates any requirements of an area -wide or statewide water quality management plan that has been approved under Section 208 or 319 of the Clean Water Act, as amended. Stormwater drainage features (i.e., diversion ditches, berms, dissipaters, retention ponds, discharge pipes, etc.) will be inspected at a minimum of twice per year, and within 24 hours of rainfall events of 0.5 inches or greater until permanent vegetation is established. Any signs of damage, settlement, clogging, silt buildup, or washouts will be documented during these inspections. If necessary, repairs to stormwater features will be made as soon as possible following detection of a problem. Any disturbed areas will be seeded and soil amendments applied as necessary to establish a healthy vegetative cover. 3.2.2 Post -Closure Erosion and Sediment Control Maintenance Erosion and sediment control during post -closure operations of the former CCR facilities at the Riverbend Steam Station will consist of monitoring and repairing stormwater features and surface erosion as described above. It is anticipated that post -closure erosion control measures at the site will include: amec foster wheeler Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 • Minimizing ground disturbances to the extent possible while mowing and performing other maintenance • Seeding and mulching of disturbed areas commencing as soon as practically possible • Employing erosion control matting or seeding and mulch on slopes and other erosion prone areas • Use of earthen berms, wattles, silt fences, riprap, or equivalent devices down gradient of disturbed areas, and at intervals along grassed waterways, until such time as permanent vegetation is established • Maintaining an adequate vegetative ground cover with a suitable seed mix and soil amendments • Placement of riprap at the, inlets and outlets of stormwater pipes Adequate erosion control measures will be provided to prevent sediment from leaving the site. Stormwater features and slopes within the former CCR facilities will be periodically checked for erosion and vegetative quality, fertilized, and mowed. Slopes will be observed for erosion, cracking, sliding, sloughing, and seepage. Slopes identified as needing maintenance will be repaired as soon as practical and as appropriate to correct deficiencies. Repair activities may include re -shaping the slope, filling in low areas, and/or seeding. 3.2.3 Post -Closure Vegetation Maintenance Vegetation maintenance during post -closure operations of the former CCR facilities at the Riverbend Steam Station will consist of periodic mowing at a minimum of twice per year, and other maintenance activities as needed until permanent vegetation is established and, where necessary, to enable access to stormwater and groundwater monitoring features during the post -closure period. Post -closure maintenance may also include applying temporary seeding and installation of temporary erosion controls as required until a permanent ground cover is established. Post - closure mulching may be used to stabilize areas where final grade has been reached and/or vegetation is inadequate. Soil mulch materials may include wood chips, straw, hay, jute matting, and synthetic fibers. Mulches allow for greater water retention, reduce runoff, and improve soil moisture and temperature conditions. Mulch will also help retain seeds, fertilizer, and lime when it is applied. A minimum of 4,000 pounds per acre of straw mulch is typically applied when establishing permanent seeding areas. Steeper slopes (3:1 horizontal to vertical or steeper) should be protected with erosion control matting. Temporary and permanent seeding will be applied as specified in the current Duke Vegetation Maintenance Implementation Plan (VMIP) using prescribed seasonal seed mixes or over - seeding mixes. Alternatively, seeding may be applied in accordance with the NCDEQ "Erosion and Sediment Control Planning and Design Manual' dated May 2013, or latest revision. Typical seed mix applications for permanent seeding are as follows: to. N� amec foster wheeler 0 Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 Table 3.1: Permanent Seeding Fall to Early Spring - September through April Species Pounds per Acre Kentucky 31 Tall Fescue (Festuca arundinacea) 100 I. Rye Grain (Secale cereale) 50 Spring to Summer - May through August Species Pounds per Acre German Millet (Setaria italica) 50 Post -closure application of soil amendments, including fertilizer and lime, may be required to establish or improve the vegetative ground cover pursuant to soil sampling and testing results. North Carolina Department of Agriculture soil test(s) may be conducted to assess soil nutrient requirements. Typical soil amendment applications for permanent seeding are as follows: Table 3.2: Permanent Seeding Soil Amendments Soil Amendment Pounds per Acre Agricultural limestone 4,000 Fertilizer (10-10-10) 1,000 Mulch (straw) 4,000 3.3 Facility Contact Information Duke will be responsible for post -closure maintenance and monitoring. Correspondence regarding the Riverbend Ash Basins should be directed to: Duke Energy Carolinas, LLC Riverbend Steam Station 175 Steam Plant Rd Mt. Holly, North Carolina 28120 (704) 263-3200 Station Sponsor for Ash Basins Operations or Environmental Professional The physical address of the proposed Riverbend Ash Basins is the same as above. amec faster wheeler 7 Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 3.4 Post -Closure Planned Use The CCR facilities at the Riverbend Steam Station will be vegetated following closure. Site access to the public will remain restricted through closure and post -closure care periods. The final long term disposition of the site has not been determined at this time and there are no current anticipated post -closure uses for the former Ash Basins, Dry Ash Stack, and Cinder Pit Area. The short term disposition of the site will be grading the site to drain, establishing the vegetative cover, and maintaining the site in an undeveloped state. Duke Energy will obtain approval from NCDEQ if a proposed post -closure use is identified. 3.5 Certification Within 60 days following completion of the post -closure care period, a notification will be prepared that the post -closure care has been completed. The notification will include the certification of a qualified professional engineer verifying that the post -closure care has been completed in accordance with the Removal Plan and the OM&M Plan. The notification will be placed in the facility Operating Record. amec foster wheeler A Amec Foster Wheeler Environment & Infrastructure, Inc. June 30, 2016 Post -Closure Operations Maintenance and Monitoring Plan Riverbend Steam Station Site Analysis and Removal Plan Revision 0 APPENDIX A Example Post -Closure Monitoring Form Duke Energy - Riverbend Steam Station DUKEAsh Basin Post -Closure Monitoring Form Date/Time: Observation Personnel: Weather/Temperature: Question No Yes If yes, location Description Corrective Actions Date Corrected Recommended Is there evidence of erosion, settlement, rutting, or potholes? Is there evidence of vegetative cover intrusion (ruts, burrows, excavation or other disturbance)? Is there evidence of stressed vegetation or bare spots? Is there evidence of erosion or sedimentation in stormwater channels, pipes, or other stormwaterfeatures? Is there evidence of regular maintenance not being performed? Is there evidence of human encroachment (trash, fire pits, tire/footprints)? General Notes: 1/1 Attachment 4 Riverbend Interim Monitoring Plan Optimization MAR 17 2020 NC DEG/OkAl _ Central O#li :, TABLE 1 IMP Optimization Summary of Analytical Parameters for Newly Installed Wells (to begin Q12019) For each of Duke Energy's 14 North Carolina facilities, new wells installed as part of the CAMA program will be monitored quarterly. Samples from these wells will be analyzed for parameters formerly included as part of the 4th Quarter 2018 IMP and additional constituents analyzed voluntarily. After four quarterly events, the monitoring frequency and/or parameter list for the new wells will be re-evaluated with NCDEQ and may be reduced and/or optimized. A summary of analytical parameters to include under this criteria is provided below. SUMMARY OF ANALYTICAL PARAMETERS FOR NEWLY INSTALLED WELLS Minimum CAMA Parameters per Q4 2018 IMP {Metals are Totals} Additional Voluntary Parameters [Dissolved (Q.45 micron filter)] Aluminum Mercury Molybdenum Aluminum Antimony Mercury Molybdenum Nickel Alkalinity (CO3/HCO3) Antimony Nickel Arsenic Arsenic Potassium Barium Phosphorus Barium Radium (226 + 228) Beryllium Potassium Selenium Silver Sodium Beryllium Selenium Boron Boron Sodium Cadmium Cadmium Strontium Calcium Calcium Sulfate Chromium Strontium Thallium Chloride Sulfide Cobalt Chromium Total Dissolved Solids (TDS) Copper Vanadium Cobalt Thallium Iron Zinc Copper Total Organic Carbon (TOC) Lead Lithium Magnesium T Manganese Hexavalent Chromium Uranium (233+234+236+238) Iron Total Suspended Solids (TSS) Lead Vanadium Magnesium IZinc Additional Voluntary Parameters (Totals) Manganese Fluoride Nitrate + Nitrite Lithium j Phosphorus Methane* Additional: Field Water Quaiit . Pararneer5 _ Dissolved Oxygen (DO) Oxidation -Reduction Potential (ORP) Redox Potential (Eh) Turbidity Temperature Specific Conductance pH * W.H. Weatherspoon Power Plant only Wells for Quarterly Monitoring (23) CPA-15*/D* CPA-2S*/D* CPA-3S*/D* CPA-4S* CPA-55*/D* CPA-65* CPA-7S*/D* GWA-115/D GWA-12S/D GWA-20S GWA-2BRU GWA-3SA/D/BR GWA-9D M W-60 Table 2.11- Riverbend Riverbend Steam Station - IMP Optimization Summary of Wells, Frequency, & Parameters (to begin Q12019) Comprehensive Water level Sweep to Occur Semi -Annually Modification - February 2019 Wells for Send -Annual Monitoringl' (68) AB-8S/D BG-1S/DA _ BGAS/D BG-5D/BR GWA-1S/BRU MW-1S/D MW-2SA/D MW-35/D MW-4S/D MW-5S/D GWA-2S/BR MW-6S GWA-45/D/BR GWA-5S/D MW-75R/D/BRA MW-8S/I/D GWA-6S/D MW-9/9DA/9BRA GWA-75/D/BR MW-10 GWA-8S/D MW-11SR/DR GWA-9S/BR GWA-10S/BRU MW-13 MW-14 GWA-13S3 MW-15/15DA/15BR GWA-145/D OB-1(woterievelonly) GWA-15S/D OB-2 (water level only) GWA-20DA/BR Comprehensive Water Level Sweeps (includes wells in Semi - Annual, Quarterly, and Discontinued Monitoring Lists) GWA-225/D/BRA Optimized Quarterly & Semi -Annual Parameters for "Non -New Wells" (Total) Antimony Arsenic Iron Manganese Strontium Aluminum Alkalinity(CO3/HCO3) Calcium Beryllium Boron Sulfate Dissolved Oxygen (DO) Chromium (total) Total Dissolved Solids (TDS) Redox Potential (Eh) Chromium (hexavalent) Vanadium Lithium Cobalt Magnesium Molybdenum Nickel Nitrate + Nitrite Oxidation -Reduction Potential (ORP) pH Phosphorus Potassium Sodium Specific Conductance Temperature Thallium Turbidity Discontinue Sampling Ils/Water Level Only ( BG-3S/D BG-4BR GWA-13D To Be Re A GWA-9BRA GWA-20BRA GWA-22SA MW-4SA AB-SS/D AB-2S/D GWA-23S/DA/BR A = Comprehensive Site Assessment ,is = Constituents of Interest MA, CoaI Ash Management Act :DEQ= North Carolina Department of Environmental Quality ami-Annual monitoring events are scheduled to be performed concurrently with two Quarterly monitoring events per year and will include the wells listed under Quarterly for :pective events. ew wells installed as part of the LAMA program will be monitored quarterly. Samples from these wells will he analyzed for parameters formerly included as part of the 4th Quarter 18 IMP and additional constituents analyzed voluntarily (see Table 1). After four quarterly events, the monitoring frequency and/or parameter list for the new wells will be re- aluated with NCDEQ and maybe reduced and/or optimized. Replacement wells will not be considered "new wells" and will follow the respective monitoring protocol for the well in rich they replace; however, additional parameters maybe included voluntarily. WA-13S will be temporarily sampled until replacement well GWA-22SA is installed. After GWA-22SA is installed: 1. Sampling of GWA-13S will be discontinued 2. Semi-annual water level measurements of GWA-13S will continue