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Home My WebLink About1804_DukeMarshall_DryAshLFNo1_CCVReport_FID1691393_20220622(' DUKE ENERGY-. June 30, 2022 North Carolina Department of Environmental Quality Division of Waste Management Solid Waste Section 2090 U.S. Highway 70 Swannanoa, NC 28778 Attn: Ms. Sarah Moutos (submitted electronically) Re: Clean Closure Verification — Visual Confirmation and PLM Results Dry Ash Landfill Phase I Permit No.: 1804-INDUS Marshall Steam Station Terrell, North Carolina 28682 Dear Ms. Moutos, 526 South Church St. Charlotte, NC 28202 Mailing Address P.O. Box 1006 Mail Code EC 13K. Charlotte, NC 28201-1006 717-982-0986 Duke Energy is submitting the Marshall Steam Station Dry Ash Landfill Phase I (Permit No. INDUS-1804) Clean Closure Verification - Visual Confirmation and PLM Results report for review and approval, per the August 6, 2021 letter titled Approval, Permit Modificiation, Phase 1 Closure by Excavation Plan. The report was prepared by S&ME., on behalf of Duke Energy. This report includes visual inspection documentation, PLM sampling results, and lab reports to document the completion of CCR removal within the limit of waste of the Dry Ash Landfill Phase I. The visual and sampling CCR removal verification criteria were documented and collected in accordance with the Excavation Soil Sampling Plan, Marshall Steam Station, For Dry Ash Landfill Phase 1 (Rev 2), dated December 2019, and included as Appendix I of the Application for Permit Modification - Closure by Excavation, approved on August 6, 2021, and in accordance with the soil closure guidelines Duke Energy received from the North Carolina Department of Environmental Quality (NCDEQ) on November 4, 2016. This submittal is being transmitted electronically only. If you have any questions or need additional information regarding this submittal, please contact me at Ash ley.Healy(c�duke-energy.com or (717) 982- 0986. Regards, Z14VA Ashley Healy, P.G. Environmental Services Attachments: Clean Closure Verification — Visual Confirmation and PLM Results, Duke Energy Marshall Steam Station — 1804 Phase 1 Dry Ash Landfill (S&ME, Inc., 2022) www.duke-energy.com Page 1 of 2 cc (via e-mail): Claire Osborn, NCDEQ Ed Mussler, NCDEQ Sherri Stanley, NCDEQ Scott Saunders, Duke Energy Kyle Baucom, Duke Energy Chris Varner, Duke Energy James Malloy, Duke Energy John Metcalf, Duke Energy Dan Zakary, Duke Energy Tyler Hardin, Duke Energy Ed Sullivan, Duke Energy Erin Kinsey, S&ME www.duke-energy.com Page 2 of 2 June 22, 2022 Duke Energy Marshall Steam Station EHS Groundwater & Waste Programs 8320 NC Highway 150 Terrell, North Carolina 28682 Attention: Ms. Ashley Healy, P.G. Reference: Clean Closure Verification - Visual Confirmation and PLM Results Duke Energy Marshall Steam Station — 1804 Phase 1 Dry Ash Landfill Catawba County, North Carolina S&ME Project No. 212013, Ph. 06 Ms. Healy: S&ME, Inc. (S&ME) is pleased to submit this verification report documenting field activities and analytical results supporting clean closure of the 1804 Phase 1 Dry Ash Landfill (INDUS-1804), hereafter, 1804 Ph. 1 Landfill. The 1804 Ph. 1 Landfill is located at Duke Energy's Marshall Steam Station in Catawba County, North Carolina. This report documents the verified removal of Coal Combustion Residual (CCR) material by excavation from the 1804 Ph. 1 Landfill. S&ME personnel visually observed and documented the removal of CCR material, as well as obtained soil samples for laboratory analysis to confirm the removal of CCR material. Samples were documented and collected in accordance with the "Excavation Soil Sampling Plan, Marshall Steam Station, For Dry Ash Landfill Phase 1 (Permit No. INDUS-1804), Closure by Excavation Rev. 2, dated December 2019" (hereafter, Excavation Soil Sampling Plan) included as Attachment I. Field Activities S&ME personnel were on site at the 1804 Ph. 1 Landfill for three independent sampling events in 2022 that occurred between February 81" through 141", March 3rd through 81", and April 81". During each sampling event, S&ME personnel visually observed and documented the removal of CCR material, as well as obtained soil samples for laboratory analysis concurrent with the sampling grid and sample locations at depths and frequencies outlined in Section 2.0 of the Excavation Soil Sampling Plan (Attachment 1). The sampling grid and proposed sampling locations, S&ME's actual sample locations, approximate boundary of the 1804 Ph. 1 Landfill, and the approximate ash basin boundary are shown on Figure 1: Sampling Locations — Polarized Light Microscopy (PLM) Analysis, included in Attachment 11. S&ME personnel recorded the location of each sample collected for PLM analysis in the field using a handheld Trimble GPS unit. A summary of each of the samples collected by S&ME personnel within the 1804 Ph. 1 Landfill boundary in 2022 is provided in Table 1: PLM Sample Results, Soil Sampling Summary, and Grade Comparison, included in Attachment III. A description of each sample, coordinates, depths, verification of CCR material removal, and PLM analysis results are summarized in Table 1 (Attachment III). S&ME, Inc. 12016 Ayrsley Town Blvd., Suite 2-A I Charlotte, NC 282731 p 704.523.4726 1 www.smeinc.com June 22, 2022 EHS Groundwater & Waste Programs Page 2 It should be noted that the sample depths for PLM analysis are based on depths below ground surface of the final excavation grades (i.e., approximate post CCR removal elevation) of the 1804 Ph. 1 Landfill. The total volume of CCR excavated to complete closure of the 1804 Ph. 1 Landfill was less than the estimated volume included in the Application for Permit Modification - Closure by Excavation (AECOM, 2021). The Expected Post CCR Removal Elevations provided by Trans Ash (final grades) as well as the Approximate Post CCR Removal Elevations (elevations recorded at sample locations using the handheld Trimble GPS unit in the field) are summarized in Table 1 (Attachment III). Soil samples were obtained at depths of 0 to 6 inches and 2 to 2.5 feet below ground surface at each of the sample locations using a hand auger (decontaminated in the field per Section 3.1.5 of the Excavation Soil Sampling Plan). Due to locations being initially inaccessible post CCR removal, samples collected on April 81n 2022 (locations BA40 and AZ41) were collected using a Geoprobe® rather than a hand auger. To document the sample material and visually verify CCR material has been removed from the soil, each sample was photographed prior to placing the soil in the laboratory provided sample containers; sample photos are compiled in the Photographic Log, included in Attachment IV. During each of the three sampling events, samples to be analyzed for the presence of CCR material using the PLM method were delivered by S&ME personnel, under chain -of -custody, to the Duke Energy Central Laboratory at McGuire Nuclear Station for receipt. Once samples were received and logged into the Duke Energy system, they were shipped, under chain -of -custody by the Central Laboratory, to the RJ Lee Group Laboratory for PLM analysis. PLM Analysis Laboratory Reports and Chain -of -Custody Forms are located in Attachment V. Clean Closure Verification Results The clean closure benchmark value for % CCR material in soil is 50% as noted in Section 4.1 of the Excavation Soil Sampling Plan (Attachment 1). None of the samples collected within the boundary of the 1804 Ph. 1 Landfill contained more than 8% CCR material, resulting in quantitative verification of CCR material removal from the 1804 Ph. 1 Landfill. Most samples resulted in no detections of any CCR material present in the soil samples, as summarized in Table 1 (Attachment III) and the PLM Analysis Laboratory Reports (Attachment V). It should be noted that the RJ Lee PLM Analysis Laboratory Reports (Attachment V) report results as % CCP (Coal Combustion Products); CCP and CCR material terminology are deemed interchangeable, as CCP is defined as fly ash, bottom ash, and slag. Table 1 (Attachment III) along with the Photographic Log (Attachment IV) contain documentation of S&ME personnel's visual confirmation that CCR material has been removed. As previously mentioned, Table 1 (Attachment III) also includes a grade comparison as earthwork (cut/fill operations) were ongoing at the time of each sampling event. S&ME, Inc. EHS Groundwater & Waste Programs Conclusion June 22, 2022 Page 3 CCR material removal from the 1804 Ph. 1 Landfill has been verified in accordance with the visual observation and PLM sampling criteria described in the Excavation Soil Sampling Plan (Attachment 1). S&ME thanks you for your receipt of these records. Should you have any questions or need additional information, please do not hesitate to contact us at (704) 523-4726. Respectfully Submitted, S&ME, Inc. twiatou4tkt Jasmine Tayouga Associate Project Manager Senior Reviewed By: `111111ll/// � `�`NC a � //�� • SEA!- ' 048S -- 40 Erin N. Kinsey, P.E. �%1;�141Qe Project Engineer Julie P. Robertson, P.G. (Registration No. 1995) Principal Hydrogeologist and Group Leader, Energy + Environment Enclosures: Attachment I — Excavation Soil Sampling Plan for Marshall Steam Station Attachment II - Figure 1: Sampling Locations - PLM Analysis Attachment III - Table 1: PLM Results, Soil Sampling Summary, and Grade Comparison Attachment IV — Photographic Log Attachment V — PLM Laboratory Reports and Chain -of -Custody Forms cc: James Malloy, Project Manager, Duke Energy Marshall Steam Station Michael Romanello, Project Manager, S&ME S&ME, Inc. Attachments Attachment I - Excavation Soil Sampling Plan EXCAVATION SOIL SAMPLING PLAN MARSHALL STEAM STATION FOR DRY ASH LANDFILL PHASE PERMIT NO. INDUS-1804) CLOSURE BY EXCAVATION DUKE ENERGY CAROLINAS, LLC. 526 SOUTH CHURCH STREET/ECI3K CHARLOTTE, NORTH CAROLINA 28202 [vat DUKE ' ENERGY, Waste & Groundwater Programs Revision 2 December 2019 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 TABLE OF CONTENTS SECTION PAGE 1.0 PURPOSE..........................................................................................................................1 2.0 DOCUMENTATION SUMMARY............................................................................... 2 Table 1 - Post Landfill Excavation Soil Data Collection ............................................. 2 3.0 SOIL SAMPLING METHODOLOGY......................................................................... 3 3.1 Method Summary........................................................................................................ 3 3.1.1 Equipment...............................................................................................................3 3.1.2 Sample Locations................................................................................................... 4 3.1.3 Collection of Representative Samples................................................................. 4 3.1.4 Sample Preservation, Containers, Handling and Storage ................................ 5 3.1.5 Decontamination....................................................................................................5 4.0 VISUAL CONFIRMATION OF ASH REMOVAL .................................................... 6 4.1 Pre -Excavation Documentation................................................................................. 6 4.2 Ash Removal Verification Protocol........................................................................... 6 4.2.1 Field Documentation............................................................................................. 6 4.2.2 Fill Evaluation Criteria.......................................................................................... 7 4.3 Visual Removal Not Applicable................................................................................ 7 5.0 POST EXCAVATION SOIL SAMPLING AND ANALYSIS .................................. 9 5.1 Soil Sampling................................................................................................................ 9 5.1.1 Scenario 1................................................................................................................ 9 5.1.2 Scenario 2................................................................................................................ 9 5.2 Fate and Transport Modeling................................................................................... 10 Table 2 - Soil Parameters and Analytical Methods Totals and SPLP Analysis Dry Ash Landfill Phase I to be Closed by Excavation......................................................11 Figure 1F — Marshall Steam Station Dry Ash Landfill Phase I Sample Grid ......... 12 Page i Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 1.0 PURPOSE The purpose of this Excavation Soil Sampling Plan is to provide a standardized method for collecting soil samples at the Marshall Steam Station (Marshall, Site) Dry Ash Landfill Phase I (INDUS-1804), owned by Duke Energy Carolinas, LLC where areas of excavation are included in the Application for Permit Modification - Closure by Excavation Plan - Marshall Steam Station - Dry Ash Landfill Phase / (Closure by Excavation Plan, AECOM, 2021). Soil samples described in this Excavation Soil Sampling Plan will be collected following visible ash removal from excavation areas of the unlined Dry Ash Landfill Phase I (landfill) identified in the Closure by Excavation Plan. This Excavation Soil Sampling Plan is applicable to the collection of representative soil samples. Analysis of soil samples may be chemical or physical in nature and may be used to determine the following: • Extent and magnitude of constituent occurrence • Input concentrations for groundwater flow and transport model The methodologies discussed in this Excavation Soil Sampling Plan are applicable to the sampling of soil in landfill excavation areas. For the purposes of this plan, soils are those mineral and organic materials remaining after all visible ash has been removed. Page 1 Excavation Soil Sampling Plan Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) 2.0 DOCUMENTATION SUMMARY Table 1- Post Landfill Excavation Soil Data Collection December 2019 Revision 2 Task Description Test Depth Visual Inspection on 100' X 100' grid Visually confirm primary source node removal at nodes (Figure 1) and N/A N/A document with photographs. Soil sample analysis on 100' X 100' Collect representative samples at 0 - 6 inches' grid node nodes (Figure 1) and appropriate PLM 2 25 depths. 0 - 6 inches' Soil Sample Analysis on an acre grid Collect representative samples at the Total Metals 2 2.5 7 7.5 systemz appropriate depths. SPLP 12' - 12.5' 17' - 17.5' Notes: 'If a certain six-inch sample interval does not yield sufficient soil volume to fill five 8-ounce sample bottles, the sample interval may be expanded to twelve inches to allow for sufficient soil sample volume. The revised sample interval should be appropriately documented. 2Excavation is complete once confirmed by visual inspection and PLM analysis per Section 4.0. Page 2 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 3.0 SOIL SAMPLING METHODOLOGY 3.1 Method Summary This Excavation Soil Sampling Plan has been adapted from Environmental Protection Agency (EPA) Standard Operating Procedures (SOPS) #2012 and #2006 and North Carolina Department of Environmental Quality (NC DEQ) Attachment 1 Coal Combustion Residuals Surface Impoundment Closure Guidelines for Protection of Groundwater, November 4, 2016. Soil samples are collected directly using stainless steel or plastic trowel, spade, shovel, or scoops. Following collection, soil is transferred from the sampling device to a stainless steel or plastic bowl to be homogenized. Once homogenized, the soil is transferred into Duke Energy Laboratory supplied sample bottles. Soil samples will be submitted under chain of custody for the following analyses: total metals and Synthetic Precipitation Leaching Procedure (SPLP) metals. Analytical methods for total metals and SPLP metals are described in Table 2. Ash presence is quantitatively determined by polarized light microscopy (PLM) by Duke Energy Laboratory or state approved vendor. PLM analysis passes visible light through a pair of polarizing filters to create optical effects used in identifying unknown materials. This method is commonly used in asbestos and coal ash identification. 3.1.1 Equipment • Stainless steel or plastic trowel, scoop, spade or shovel — Used for collecting soil samples from surface locations. • Sample containers — To be supplied by Duke Energy Laboratory with appropriate cooler(s). Estimated that five 8-ounce sample bottles with Teflon -lined lids will be required for each sample location and sample depth. For return of cooler to the lab, ice will be required. • Gloves — Used for personal protection and to prevent cross -contamination of samples — nitrile, disposable, powderless. • Field clothing and Personal Protective Equipment — Used as specified in the site Health and Safety Plan. • Sampling flags — Used for identifying soil sampling locations. • Field notebook — A bound book used to record progress of sampling effort and record any problems and field observations during sampling. • Three-ring binder book — Used to store necessary forms and record and track samples collected at the site. • Permanent marking pen — Used to label sample containers, document field logbooks, data sheets and chain of custody. Page 3 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 • Stainless steel or plastic spoon — Used for homogenizing soil samples within a stainless steel or plastic bowl. • Stainless steel or plastic bowl — Used for homogenizing soil samples, when applicable. • Camera — Used for photo -documentation of sample locations and samples. • GPS — Device used to obtain elevation, latitude and longitude of sample location. • Trash bag — Used to dispose of gloves and any other non -hazardous waste generated during sampling. • Decontamination supplies and equipment. 3.1.2 Sample Locations General locations for soil sampling are determined by the soil scientist in the field at a rate of one soil sample for every 1 acre of landfill area excavated. Actual sampling locations on site may vary to account for site conditions and to allow collection of representative samples. Representative samples reflect areas where all ash has been visually excavated and natural soil is observed. 3.1.3 Collection of Representative Samples For the purpose of this plan, surface soil is considered to range from 0 to 6 inches in depth, while deeper samples will be collected at a range of 2 to 2.5 feet below ground surface (bgs), 7 to 7.5 feet bgs, 12 to 12.5 feet bgs, and 17 to 17.5 feet bgs (Table 1) unless bedrock, refusal, or the water table are encountered. A surface soil sample and deeper samples will be collected at each location for every 1 acre of landfill excavated. A new pair of nitrile gloves is worn at each sampling location and each depth. Each sampling location is recorded on the site map prior to collecting the sample, if location is not already noted on the map. The GPS location of each sampling location (i.e., elevation, latitude, and longitude), sample descriptions, and area photographs are also recorded. All sampling equipment is decontaminated prior to each use irrespective of depth. The following procedure will be used to collect representative soil samples with a scoop, shovel, trowel, geoprobe, or excavator: • Locate general sampling locations. • Determine suitability of sampling location for a representative sample. • If sampling location appears to reflect representative conditions that would allow collection of a representative sample, proceed with sampling procedure. If location is not indicative of conditions that would allow collection of a representative sample, notify the project manager so an alternate location can be identified. • Using a decontaminated sampling instrument, remove the desired thickness and volume of soil from the sampling area. The sampler must obtain enough soil to fill five 8-ounce sample bottles. If a certain 6-inch sample interval does not yield Page 4 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 sufficient soil volume to fill five 8-ounce sample bottles, the sample interval may be expanded to allow for sufficient soil sample volume. The revised sample interval should be appropriately documented. • Transfer the sample into an appropriate sample or homogenization bowl. Non - dedicated containers should be adequately decontaminated. Stir for approximately one minute until there appears to be a uniform color and consistency. • Transfer homogenized sample to a labeled container(s) of appropriate size and construction for the analyses requested. • Secure sample container tightly. 3.1.4 Sample Preservation, Containers, Handling and Storage Chemical preservation of soils is generally not recommended. Cooling to 4°C on wet ice is usually the best approach, supplemented by the appropriate holding time for the analyses requested. The Duke Energy Laboratory will supply the appropriate sample bottles for the collected soil samples. The sample volume is a function of the analytical requirements and the Duke Energy Laboratory will ensure the appropriate number of bottles are supplied. Ensure chain of custody is completed for sample bottle return to the Duke Energy Laboratory. Table 2 contains a list of parameters to be analyzed with corresponding reporting units and analytical methods. If a parameter or group of parameters is not included in Table 2, the laboratory performing the analysis should be contacted to determine the appropriate sample bottles, volumes, and preservatives. All non -dedicated sampling devices should be decontaminated and wrapped in plastic. The sampling device should remain in this wrapping until it is needed. Each sampling device should be used for only one sample and then decontaminated or disposed of. Non -dedicated sampling devices should be cleaned in the field using the decontamination procedure described below. 3.1.5 Decontamination Decontamination procedures can be time consuming; having a sufficient quantity of sampling tools available is recommended. All non -dedicated sampling equipment must be decontaminated prior to reuse. Equipment decontamination consists of: 1. Detergent wash and brush cleaning 2. Tap water rinse 3. De -ionized water rinse 4. Air dry 5. Wrap sampling tools with plastic Page 5 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 4.0 VISUAL CONFIRMATION OF ASH REMOVAL 4.1 Pre -Excavation Documentation Closure by excavation is defined herein as removing the primary source (primary source of potential constituents of interest) to the point that ash is not visible to the unaided eye at the ground surface. Closure by Excavation in this Excavation Soil Sampling Plan, can refer to areas of excavation occurring under any closure scenario. Primary source ash is the only waste material that was deposited in the landfill. This method is intended solely to verify and document primary source ash removal and is not intended to validate environmental quality standards of the subsurface (considered the secondary source of potential constituents of interest). Pre -excavation documentation would consist of: • Review topographic mapping, aerial photography, construction drawings, and boring logs to estimate the pre -ash placement topography and/or ash/soil interface Preparation of an landfill figure illustrating a grid spacing of 100 feet (Figure 1). Each grid point (node) will be assigned a unique identifier. Each node of the grid spacing (grid point) will represent a visual verification location. 4.2 Ash Removal Verification Protocol Ash excavation will be considered complete based on visual and PLM confirmation that all ash has been removed. Ash removal will be based on sampling of the ash/soil interface and analysis by PLM. Soil samples will be examined utilizing methods outlined in American Society for Testing and Materials (ASTM) D2488, Standard Practice for Description and Identification of Soils (Visual -Manual Procedure). Vertical and horizontal excavation of ash can terminate when the remaining material is documented using PLM to contain less than 50% ash. Project will excavate ash until a visible change in color or texture confirms removal of all ash. This location shall be referred to as the ash/soil interface. If visual evaluation is inconclusive, then request additional evaluation to confirm ash removal. 4.2.1 Field Documentation Evaluate the excavated surface elevation relative to the pre -ash placement topography. Periodically check bottom elevation to evaluate if fill material is present above historic bottom elevation. Visual confirmation will be performed on a 100-foot grid system (Figure 1) unless conditions prevent such confirmation, as described in Section 4.3. Soil sampling will be performed on a 100-foot grid system and will be analyzed using PLM. • Personnel will locate each node by GPS or survey control, determine elevation, and evaluate whether that point is above or below the historic bottom elevation. Personnel will then observe the surface area represented by the node, to note if visible ash is present at the surface. If present, the conditions and location should be documented, and excavation will need to continue. If the evaluation indicates the surface soils are residuum or bedrock, then hand auger to two feet below surface (or refusal) and perform visual -manual classification of the soils at the surface and depth according to ASTM method D2488. Submit sample from surface and depth (or Page 6 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 shallower if refusal) for PLM analysis. The conditions shall be documented by taking photographs. The classification indicator for fly ash will be grey to black silt -sized particles with no plasticity. The classification indicator for bottom ash will be grey to black sand to gravel sized particles and porous. • If the node point elevation is near the historic bottom elevation, then personnel can conclude the primary source is removed when the following criteria are met: 1. Residuum is indicated by observation 2. Soil is confirmed by visual manual classification (ASTM D2488) and PLM analysis less than 50% 4.2.2 Fill Evaluation Criteria The following procedure provides an approach that can be used to ascertain if the fill material can remain in place. The procedure specified is based on the fill material and depth. If the elevation is less than eight feet above the historic bottom elevation of the landfill and residuum is not observed, test pits may be excavated to historic bottom elevation or until residuum or bedrock is encountered, but no more than eight feet below the surface. o Personnel will evaluate existing information to determine if the test pits are necessary. If necessary, personnel may recommend excavating test pits at a frequency no tighter than 100 feet by 100 feet. o If visible ash is not discovered based on information defined above, the primary source removal may be confirmed. o If visible ash is discovered, continue excavation. • If the elevation is more than eight feet above historic bottom elevation of the landfill and residuum is not observed, discuss with CCP Closure Personnel. o CCP Closure Personnel will confirm historic information and recommend a drilling and sampling program at a frequency no tighter than 100 feet by 100 feet to evaluate the presence of ash below the fill material in accordance with the information defined above. If unusual features are revealed by the drilling, CCP Closure Engineering may request/recommend additional borings. Exploration is to be performed by continuous sampling during drilling. o If visible ash is not discovered based on information defined above, then the primary source removal may be confirmed. o If visible ash is discovered, continue excavation. 4.3 Visual Removal Not Applicable If possible, excavation of ash should continue even if groundwater is encountered. Visual documentation is challenging to complete when removal occurs in saturated conditions. Excavation of ash could be required in areas below the water table or ponded ash intended for removal by dredging. Page 7 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 Saturated ash conditions are not anticipated during the excavation of the Dry Ash Landfill Phase I since the proposed excavation grades are approximately 10 feet greater than recent groundwater levels in the excavation area. However, if saturated conditions become present, a plan will be submitted to NC DEQ by Duke Energy pertaining to the removal of ash if these conditions or other restricting factors occur. Page 8 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 5.0 POST EXCAVATION SOIL SAMPLING AND ANALYSIS 5.1 Soil Sampling Analytical evaluation of the remaining soils (less than 50% ash per PLM analysis) will be necessary to evaluate the extent of potential secondary source impacts depending on the depth of the water table and any proposed institutional or engineering controls that may be used in the area of excavation. Soil sampling will not be required if refusal or the top of bedrock are encountered, or the remaining soils are below the water table. Soil samples for laboratory analysis must be collected in a manner that will ensure a relatively uniform distribution of particles throughout the 6-inch sample. The systematic approach and design for soil sampling and analysis is dependent upon two scenarios: • Scenario 1: Remaining soil (containing less than 50% ash per PLM analysis) is located above the seasonal high water table and final constructed institutional and/or engineering controls will restrict infiltration from the surface reaching the water table (e.g. installation of a liner system). Scenario 2: Remaining soil (containing less than 50% ash per PLM analysis) is located above the seasonal high-water table and infiltration from the surface would continue to reach the water table. 5.1.1 Scenario 1 Confirmation sampling will include discrete surface samples collected from the first six inches of the soil. Sampling will be performed on an acre grid system. This sample collection methodology shall be sufficient to characterize the horizontal extent of any remaining potential secondary source impacts for comparison with the NC DEQ Preliminary Soil Remediation Goals (PSRG). The samples shall be analyzed by a North Carolina certified laboratory for total concentrations for the parameters defined in Table 2. No SPLP testing is required. 5.1.2 Scenario 2 Confirmation sampling will include collection of both discrete surface and subsurface soil samples performed on an acre grid system. Discrete surface samples will be collected from the first six inches of the soil and a subsurface soil sample will be collected at 2 to 2.5 feet below ground surface (bgs), 7 to 7.5 feet bgs, 12 to 12.5 feet bgs, and 17 to 17.5 feet bgs unless refusal, bedrock or the water table are encountered. The use of a geoprobe or excavator is anticipated. This sample collection methodology shall be sufficient to characterize both the horizontal and vertical extent of any remaining potential secondary source impacts for comparison with the NC DEQ PSRGs and/or input into the soil leachate model. The samples shall be analyzed by a North Carolina certified laboratory for both total concentrations and SPLP for the parameter defined in Table 2. Excavation of the Dry Ash Landfill Phase I will follow sampling methods corresponding to Scenario 2, since no institutional or engineered controls are anticipated for future use of the excavation area, and therefore infiltration from the surface is anticipated to continue to reach the water table in the former footprint of the landfill. Page 9 Excavation Soil Sampling Plan December 2019 Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) Revision 2 5.2 Fate and Transport Modeling Contingency for stabilization of remaining amounts of potential secondary source impacts in a manner that will meet the intent of North Carolina Groundwater 2L Rules and closure requirements shall be considered as site conditions dictate. Provisions to develop groundwater flow and transport models to evaluate protection of groundwater criteria if potential secondary source material are left in place shall be considered. In addition, the possibility of metals leaching from a potential change in pH and geochemical conditions related to dewatering and excavation shall be considered along with plans for groundwater models to assess resulting site conditions. Page 10 Excavation Soil Sampling Plan Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) December 2019 Revision 2 Table 2 - Soil Parameters and Analytical Methods Totals and SPLP Analysis Dry Ash Landfill Phase I to be Closed by Excavation INORGANIC COMPOUNDS UNITS METHOD' Aluminum mg/kg or µg/I EPA 6010D Antimony mg/kg or µg/I EPA 6020B Arsenic mg/kg or µg/I EPA 6020B Barium mg/kg or µg/I EPA 6010D Beryllium mg/kg or µg/I EPA 6020B Boron mg/kg or µg/I EPA 6010D Cadmium mg/kg or µg/I EPA 6020B Calcium mg/kg or µg/I EPA 6010D Chloride mg/kg or µg/I EPA 9056A Chromium mg/kg or µg/I EPA 6010D Cobalt mg/kg or µg/I EPA 6020B Copper mg/kg or µg/I EPA 6010D Hexavalent Chromium mg/kg or µg/I EPA Method 7199/218.7 Iron mg/kg or µg/I EPA 6010D Lead mg/kg or µg/I EPA 6020E Magnesium mg/kg or µg/I EPA 6010D Manganese mg/kg or µg/I EPA 6010D Mercury mg/kg or µg/I EPA Method 7470A/7471B Molybdenum mg/kg or µg/I EPA 6010D Nickel mg/kg or µg/I EPA 6010D Nitrate as Nitrogen mg/kg or µg/I EPA 9056A pH SU EPA 9045D Potassium mg/kg or µg/I EPA 6010D Selenium mg/kg or µg/I EPA 6020B Silver mg/kg or µg/I EPA 6020B Sodium mg/kg or µg/I EPA 6010D Strontium mg/kg or µg/I EPA 6010D Sulfate mg/kg or µg/I EPA 9056A Thallium (low level) (SPLP Extract only) mg/kg or µg/I EPA 6020B Vanadium mg/kg or µg/I I EPA 6020B Zinc mg/kg or µg/I EPA 6010D Notes• 1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted above (or similar approved methods). Soil samples will also be analyzed for leaching potential using SPLP Extraction Method 1312 in conjunction with USEPA Methods 6010/6020 (or similar approved methods) if Scenario 2 is applicable. Page 11 Excavation Soil Sampling Plan Marshall Steam Station — Dry Ash Landfill Phase I (INDUS-1804) December 2019 Revision 2 Figure 1F — Marshall Steam Station Dry Ash Landfill Phase I Sample Grid Page 12