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HomeMy WebLinkAboutNC0004961_Revised Coal Pile Assessment Tech Memos_20180606TECHNICAL MEMORANDUM Page 1 of 3 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Allen - Coal Pile Assessment TM Rev1.docx Date: Revised June 1, 2018 Submitted January 12, 2018 File: 1026.17.05J To: Courtney Murphy (Duke Energy) Cc: Kathy Webb (SynTerra) From: Chris Suttell Subject: Allen Steam Station Coal Pile Assessment Work Plan Introduction The initial technical memorandum describing groundwater and soil assessment activities for the Allen Steam Station (Allen, Plant, or Site) was submitted to the North Carolina Department of Environmental Quality (NC DEQ) in January 2018. In correspondence dated May 2, 2018, NC DEQ approved the planned assessment activities and provided comments to be incorporated. This revised technical memorandum incorporates the NC DEQ comments (see Table 1 for details of the comments and responses). Duke Energy Carolinas, LLC (Duke Energy) owns and operates the Allen Steam Station (Allen, Plant, or Site) in Belmont, Gaston County, North Carolina. The Site encompasses approximately 1,009 acres. Groundwater and soil assessment activities proposed for the coal storage area (coal pile) are described herein. Regulatory Background In 2014, The North Carolina General Assembly passed the Coal Ash Management Act (CAMA). CAMA required owners of a coal combustion residuals (CCR) surface impoundment to conduct detailed assessment of site groundwater within and around the CCR surface impoundments. Primary sources of CCR-related constituents were identified during the Comprehensive Site Assessment (CSA) for CAMA to be the ash basins, which consists of the active ash basin and the inactive ash basin. Groundwater monitoring wells were installed south and west of the coal pile during CAMA-associated fieldwork. Additionally, wells were installed for compliance with the Environmental Protection Agency’s Coal Combustion Residuals (CCR) Rule in the vicinity of the coal pile area. Boron, an inorganic constituent, is commonly used as an indicator of CCR impacts to groundwater. Groundwater sampling results from the wells near the coal pile did not indicate Coal Pile Assessment Work Plan Submitted January 12, 2018, Revised June 1, 2018 Duke Energy Carolinas, LLC, Allen Steam Station SynTerra Page 2 of 3 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Allen - Coal Pile Assessment TM Rev1.docx elevated concentrations of boron. However, CAMA and CCR assessment data indicated constituents, such as arsenic, beryllium, cadmium, nickel, selenium, thallium, and zinc in groundwater samples at concentrations uncharacteristic of other samples from around the ash basins. For these reasons, Duke Energy understands the coal pile area soils and underlying groundwater to be a potential additional primary and “secondary source” of inorganic constituents that will be assessed apart from CAMA or the CCR Rule. Station Description Power generating operations began at Allen in 1957 and the Plant remains active. Coal used to fuel power generating units is transported to Allen by railroad and is stored on approximately 18.5 acres south of the power generation plants and north of the ash basins. CCR have been sluiced to the ash basin system located south of the power generating units, which includes an active ash basin and the inactive ash basin. Topography at the site generally slopes downward from the west to the Catawba River to the east of the Plant and coal pile area. Currently, a portion of the coal pile is being modified as part of the Allen Steam Station Water Re-direction Program to allow construction of a lined holding basin on the east side of the historical coal pile footprint. Part of the construction of the holding basin includes installation and operation of extraction wells to de-water the area. As of the date of this memorandum, construction of the dewatering system is complete and the system is operating at an approximate flowrate of 80 gallons per minute. Eight observation wells were installed in the vicinity of the holding basin construction project, and water levels are being recorded on a daily basis. Pressure transducers have also been installed in wells in close proximity to the coal pile to monitor water level changes on a more frequent basis. Coal Pile Area Assessment Objectives Objectives of the coal pile area assessment include the following: Characterize inorganic constituents associated with coal pile area soils Characterize inorganic constituent concentrations in soil and groundwater along the coal pile perimeter Compare inorganic constituent concentrations in coal pile area to Site background concentrations Coal Pile Assessment Work Plan Submitted January 12, 2018, Revised June 1, 2018 Duke Energy Carolinas, LLC, Allen Steam Station SynTerra Page 3 of 3 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Allen - Coal Pile Assessment TM Rev1.docx Soil Assessment Coal pile area soils will be sampled and analyzed for inorganic parameters to determine if they are a potential secondary source of CCR-related constituents that can leach into underlying groundwater. Soil samples will be collected at proposed monitoring well locations (CP-1 through CP-6) as part of well installation activities (Figure 1). Soil samples will be collected at approximately 2-foot intervals to the top of the groundwater table (approximately 10 feet below ground surface). An additional soil sample will be collected below the water table within the new well screened intervals. Soil samples will be analyzed for inorganic parameters listed on Table 2. Groundwater Assessment Twelve coal pile (CP) assessment groundwater monitoring wells will be installed to characterize coal pile area groundwater in shallow and deep groundwater zones. The shallow zone is considered groundwater within soil and saprolite material. The deep zone is considered groundwater within partially weathered rock transition zone material underlying the shallow zone and overlying competent bedrock. Six shallow (“S”) and six deep (“D”) groundwater monitoring wells (CP-1S/D through CP-6S/D) will be installed as well pairs. Proposed CP well installation locations are shown on Figure 1 and proposed well details are provided as Table 3. Specific well locations may be shifted depending upon access and field conditions at the time of installation. Groundwater samples will be analyzed for inorganic constituents listed on Table 4. Coal Pile Assessment Report A coal pile assessment report will be prepared once soil and groundwater sample analytical data is received. The report will include the following components: 1) Site History and Source Characterization 2) Site Geology and Hydrogeology 3) Sampling Results 4) Site Conceptual Model 5) Conclusions and Recommendations ATTACHMENTS: Table 1: Response to NC DEQ Comments - Coal Pile Assessment Work Plan Table 2: Soil Analytical Methods Table 3: Proposed Coal Pile Assessment Soil Samples and Monitoring Wells Table 4: Groundwater Analytical Methods Figure 1: Proposed Coal Pile Assessment Sample Locations Coal Pile Assessment Work Plan Submitted January 12, 2018, Revised June 1, 2018 Duke Energy Carolinas, LLC, Allen Steam Station SynTerra P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Allen - Coal Pile Assessment TM Rev1.docx ATTACHMENTS TABLE 1 RESPONSE TO NC DEQ COMMENTS - COAL PILE ASSESSMENT WORK PLAN ALLEN STEAM STATION DUKE ENERGY CAROLINAS, LLC, BELMONT, NC Page 1 of 4 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Table 1 - Response to DEQ Comments- Allen Coal Pile Assessment.docx The Allen Steam Station Coal Pile Assessment Work Plan Technical Memorandum was submitted to the North Carolina Department of Environmental Quality (NC DEQ) Division of Water Resources in January 2018. NC DEQ’s approval of the work plan, with comments on the submittal, was forwarded to Duke Energy on May 2, 2018. Table 1 (below) includes the NC DEQ comments with a brief summary response and/or the section(s) of the current submittal containing a detailed response. NC DEQ Comment 1 The coal pile assessment report is expected to contain necessary evaluations and interpretations associated with collected data and not just present the results of the assessment. This may mean incorporation of groundwater assessment data, coal combustion residuals (CCR) program data, or any other necessary information needed to draw appropriate, technically supportable conclusions. Response Summary Data will be collected and used in the coal pile assessment report to achieve the objectives of characterizing inorganic constituents in coal pile area soils and groundwater, including comparison with site background concentrations. As suggested, this may include CAMA and CCR program data and other available and relevant data associated with improvement projects in the vicinity of the coal pile. NC DEQ Comment 2 The following information shall be presented as part of an evaluation of the hydraulic effect of the dewatering system in the vicinity of the coal pile before and after operations commenced:  A groundwater elevation map prior to operation of the dewatering system,  A groundwater elevation map for initial start-up (or as close to it as possible),  A groundwater elevation map under existing conditions as part of the coal pile assessment, and  A comparison of data collected as part of the coal pile assessment to groundwater assessment and/or CCR data as well as data collected as part of the permitting process for the dewatering system such as aquifer testing, etc. Response Summary The hydraulic effect of the dewatering system will be evaluated, including presentation of the information as suggested. Data from transducers installed in existing wells in the vicinity of the coal pile will help support this evaluation. NC DEQ Comment 3 The following technical direction shall be incorporated into the coal pile assessment:  It was stated in the Coal Pile Assessment Work Plan that Duke would “Compare Table 1 - Response to NC DEQ Comments - Coal Pile Assessment Work Plan June 1, 2018 Duke Energy Carolinas, LLC, Allen Steam Station SynTerra Page 2 of 4 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Table 1 - Response to DEQ Comments- Allen Coal Pile Assessment.docx inorganic constituent concentrations in coal pile area to Site background concentrations.” Analytical results from wells located downgradient of the ash basin shall also be used for comparison. • There have been constituents observed at the GWA-6 well cluster that are likely attributable to other activities at the Site, which should be considered as part of this assessment since the well is situated between the coal pile and the inactive ash basin. • Ensure that when analyzing soil samples for constituents identified in Table 1 [now Table 2], the reporting limit is not above the North Carolina Division of Waste Management’s Inactive Hazardous Sites Branch Protection of Groundwater value for that constituent. • Hexavalent chromium shall be added as a parameter for analysis as part of the coal pile assessment in Table 3 [now Table 4]. • Groundwater samples from locations CP-2S/D, CP-4S/D, and CP-6S/D shall be analyzed for total uranium, radium 226, and radium 228. • Samples from locations CP-2S/D, CP-4S/D, and CP-6S/D shall be collected at appropriate depths and analyzed for leachable inorganics suing Synthetic Precipitation Leaching Procedures. Response Summary • In addition to analytical results being compared with background values, analytical results from wells located downgradient of the ash basins will also be compared with results from the wells downgradient of the coal pile to determine whether there are notable differences in groundwater quality downgradient of the different source areas. • Constituents observed at the GWA-6 well cluster are included in Table 4 (formerly Table 3), which has been updated to be consistent with ongoing IMP sampling parameters. Results from GWA-6 will be considered as part of the coal pile assessment to evaluate the potential source(s) of constituents in groundwater in the vicinity of this well cluster. • Coal pile assessment soil samples will be analyzed using laboratory reporting limits at or less than those outlined by the North Carolina Division of Waste Management’s Inactive Hazardous Sites Branch for Protection of Groundwater. • Hexavalent chromium will be added as a parameter for analysis as part of the coal pile assessment. Table 4 (formerly Table 3) of the work plan technical memorandum has been updated accordingly. • Groundwater samples from locations CP-2S/D, CP-4S/D, and CP-6S/D will be analyzed for total uranium, radium-226, and radium-228. The analytical methods for these analytes are included in Table 4 (formerly Table 3). • Soil samples from locations CP-2S/D, CP-4S/D, and CP-6S/D will be analyzed for leachable inorganics using Synthetic Precipitation Leaching Procedures. Table 1 - Response to NC DEQ Comments - Coal Pile Assessment Work Plan June 1, 2018 Duke Energy Carolinas, LLC, Allen Steam Station SynTerra Page 3 of 4 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Table 1 - Response to DEQ Comments- Allen Coal Pile Assessment.docx NC DEQ Comment 4 The following revisions to the coal pile assessment plan are recommended: • While sonic drilling has been recommended as the method of installation for the coal pile assessment wells, using sonic drilling for the deeper boreholes may result in complications, therefore, it is recommended traditional drilling methods (i.e., auger, air, etc.) be employed for wells completed in bedrock or partially weathered rock. If sonic drilling is chosen, Duke Energy must ensure that the borehole is properly flushed to remove drilling fluid/cuttings prior to installation of the monitoring well to reduce the likelihood of sediment accumulation in the monitoring well which will cause water quality issues and potentially make development/sampling difficult. These potential complications may result in installation of replacement wells. • Proposed well construction involves submerging well screens below the water table. It is recommended that for shallow wells the screen should not be submerged (intentionally), but should bracket the water table and if necessary extend the screen interval to 15-ft to allow the shallow well to accommodate water table fluctuations. • CP-1S/D is proposed in a parking/staging area of the site. It is recommended that this well be moved further south in the grassy area (see attached map). Positioning a well in a parking/storage area can be problematic for locating the well and make sampling the well more difficult due to activities in the parking/storage area. • It is recommended CP-6S/D be moved further south and install the well upgradient of the S-9 location to have a better understanding of groundwater quality and aid in evaluation of whether the coal pile is contributing to impacts observed at S-9. Also, it is recommended to adjust CP-5S/D a little further south to compensate for moving CP-6S/D (See attached map). Response Summary • Sonic drilling remains SynTerra’s recommended drilling method for the coal pile assessment. SynTerra provided rationale for the use of sonic drilling techniques in the 2014 CSA Work Plans for the Duke Energy Progress sites. The rationale highlighted the advantages of sonic drilling. Compared with other drilling methods capable of achieving targeted well depths, which includes drilling into partially weathered rock/transition zone, sonic drilling: o Produces continuous cores of unconsolidated and consolidated material with high recovery percentage that can be used for soil sampling and for observation to determine appropriate depth intervals for well construction. o Minimizes formation compaction, borehole disturbance, and smearing through the use of vibration and slow rotation rates, which minimize the skin friction on the outer walls of the tooling. Table 1 - Response to NC DEQ Comments - Coal Pile Assessment Work Plan June 1, 2018 Duke Energy Carolinas, LLC, Allen Steam Station SynTerra Page 4 of 4 P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\Table 1 - Response to DEQ Comments- Allen Coal Pile Assessment.docx o Improves well construction reliability as well materials are installed within the outer steel casing as it is withdrawn and sonic vibration eliminates the potential for sand bridging. o Requires less drilling fluids, and the fluids are potable water rather than mud slurry. This minimizes the amount drilling fluids and sediment that must be removed later in the well development process. After installation, the boreholes will be properly flushed/developed to remove fluids and cuttings prior to the installation of the monitoring wells. As recommended by NC DEQ during a meeting on May 18, 2018, Duke/SynTerra will consult closely with drillers to use appropriately sized filter packs and screens. Centralizers will be used in wells to ensure uniform annulus space for the filter packs. • The approach for well screen intervals was outlined in the May 18, 2018 meeting “Items to Discuss” agenda and in an email from Duke Energy (J. Toepfer) to NCDEQ (S. Lanter). NCDEQ responded via email (S. Lanter to J. Toepfer) on May 23, 2018, stating “During the May 18, 2018 teleconference concerning Coal Pile Assessment Plans, Duke Energy requested concurrence concerning the proposed technical approach for installing well screens approximately 5 feet below the water table. Based on the supporting rationale presented during the meeting, the Division agrees with the proposed plans for well construction to support the assessment. However, the Division may expect news wells for other scopes of work to have screened intervals installed to bracket the water table.” • CP-1S/D, CP-5S/D, and CP-6S/D have been moved accordingly as shown on the revised work plan Figure 1. Well locations will be appropriately vetted in the field with input from NC DEQ based on access, utilities, and other potential impacts. TABLE 2 SOIL ANALYTICAL METHODS ALLEN STEAM STATION DUKE ENERGY CAROLINAS, LLC, BELMONT, NC P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\ Table 2 - Soil Analytical Methods.xlsx Page 1 of 1 INORGANIC COMPOUNDS UNITS METHOD Aluminum mg/kg EPA 6010D Antimony mg/kg EPA 6020B Arsenic mg/kg EPA 6020A Barium mg/kg EPA 6010C Beryllium mg/kg EPA 6020B Boron mg/kg EPA 6010C Cadmium mg/kg EPA 6020A Calcium mg/kg EPA 6010C Chloride mg/kg EPA 9056A Chromium mg/kg EPA 6010C Cobalt mg/kg EPA 6020A Copper mg/kg EPA 6010C Iron mg/kg EPA 6010C Lead mg/kg EPA 6020A Magnesium mg/kg EPA 6010C Manganese mg/kg EPA 6010C Mercury mg/kg EPA Method 7471B Molybdenum mg/kg EPA 6010C Nickel mg/kg EPA 6010C Nitrate as Nitrogen mg/kg EPA 9056A pH SU EPA 9045D Potassium mg/kg EPA 6010C Selenium mg/kg EPA 6020A Sodium mg/kg EPA 6010C Strontium mg/kg EPA 6010C Sulfate mg/kg EPA 9056A Thallium (low level) (SPLP Extract only)mg/kg EPA 6020A Total Organic Carbon mg/kg EPA 9060 Vanadium mg/kg EPA 6020A Zinc mg/kg EPA 6010C Notes: 1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted above. meq/100g - millequivalents per 100 grams mg/kg - Milligrams per kilogram mV - Millivolts S.U. - Standard Unit Prepared by: RBI Checked by: CJS 2. Ash samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045; select ash samples will also be analyzed for leaching potential using SPLP Extraction Method 1312 in conjunction with USEPA Methods 6010/6020. 3. Analytical methods and reporting limits as presented were applicable at time of CSA field implementation in 2015. Analytical methods and reporting limits are updated periodically and applied as appropriate. TABLE 3 PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS ALLEN STEAM STATION DUKE ENERGY CAROLINAS, LLC, BELMONT, NC P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\ Table 3 - Allen Proposed Coal Pile Assessment Boring & Well Depths.xlsx Page 1 of 1 Monitoring Well ID Estimated Well Depth (feet bgs) Soil Sample ID (Estimated Depth Interval in feet bgs) Comments ----CP-1SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs ----CP-1SB (5-6)Unsaturated soil sample, water table ~10 feet bgs ----CP-1SB (8-9)Unsaturated soil sample, water table ~10 feet bgs CP-1S 30 CP-1SB (25-26)Soil sample from shallow well screened interval CP-1D 140 CP-1SB (135-136)Soil sample from deep well screened interval ----CP-2SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs ----CP-2SB (5-6)Unsaturated soil sample, water table ~10 feet bgs ----CP-2SB (8-9)Unsaturated soil sample, water table ~10 feet bgs CP-2S 30 CP-2SB (27-28)Soil sample from shallow well screened interval CP-2D 125 CP-2SB (122-123)Soil sample from deep well screened interval ----CP-3SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs ----CP-3SB (5-6)Unsaturated soil sample, water table ~10 feet bgs ----CP-3SB (8-9)Unsaturated soil sample, water table ~10 feet bgs CP-3S 25 CP-3SB (22-23)Soil sample from shallow well screened interval CP-3D 115 CP-3SB (112-113)Soil sample from deep well screened interval ----CP-4SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs ----CP-4SB (5-6)Unsaturated soil sample, water table ~10 feet bgs ----CP-4SB (8-9)Unsaturated soil sample, water table ~10 feet bgs CP-4S 25 CP-4SB (22-23)Soil sample from shallow well screened interval CP-4D 115 CP-4SB (112-113)Soil sample from deep well screened interval ----CP-5SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs ----CP-5SB (5-6)Unsaturated soil sample, water table ~10 feet bgs ----CP-5SB (8-9)Unsaturated soil sample, water table ~10 feet bgs CP-5S 25 CP-5SB (22-23)Soil sample from shallow well screened interval CP-5D 115 CP-5SB (112-113)Soil sample from deep well screened interval ----CP-6SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs ----CP-6SB (5-6)Unsaturated soil sample, water table ~10 feet bgs ----CP-6SB (8-9)Unsaturated soil sample, water table ~10 feet bgs CP-6S 25 CP-6SB (22-23)Soil sample from shallow well screened interval CP-6D 115 CP-6SB (112-113)Soil sample from deep well screened interval Prepared by: LWD Checked by: CJS Notes: bgs = below ground surface ~ = Approximately SynTerra recommends rotosonic drilling methods for boring and well installation Continuous cores from sonic drilling provide sufficient material for soil sampling and lithologic description. Estimated well and soil sample depths based on data from the GWA-4, GWA-5 and GWA-7 well clusters. SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet SynTerra proposes soil samples be collected from well screen intervals for potential use in MNA analysis. Number of soil samples shown is approximate. A shallower water table will result in fewer samples, and a deeper water table will result in additional samples. TABLE 4 GROUNDWATER ANALYTICAL METHODS ALLEN STEAM STATION DUKE ENERGY CAROLINAS, LLC, BELMONT, NC P:\Duke Energy Carolinas\17.ALLEN\05.EHS CAMA Compliance Support\Assessment\Coal Pile\Work Plan\Revision 1\ Table 4 - Groundwater Analytical Methods.xlsx Page 1 of 1 PARAMETER RL UNITS METHOD pH NA SU Field Water Quality Meter Specific Conductance NA µS/cm Field Water Quality Meter Temperature NA ºC Field Water Quality Meter Dissolved Oxygen NA mg/L Field Water Quality Meter Oxidation Reduction Potential NA mV Field Water Quality Meter Eh NA mV Field Water Quality Meter Turbidity NA NTU Field Water Quality Meter Aluminum 0.005 mg/L EPA 200.7 or 6010D Antimony 0.001 mg/L EPA 200.8 or 6020B Arsenic 0.001 mg/L EPA 200.8 or 6020B Barium 0.005 mg/L EPA 200.7 or 6010D Beryllium 0.001 mg/L EPA 200.8 or 6020B Boron 0.05 mg/L EPA 200.7 or 6010D Cadmium 0.001 mg/L EPA 200.8 or 6020B Chromium 0.001 mg/L EPA 200.8 or 6020B Cobalt 0.001 mg/L EPA 200.8 or 6020B Copper 0.001 mg/L EPA 200.8 or 6020B Hexavalent Chromium 0.000025 mg/L EPA 218.7 Iron 0.01 mg/L EPA 200.7 or 6010D Lithium 1 mg/L EPA 200.7 or 6010D Lead 0.001 mg/L EPA 200.8 or 6020B Manganese 0.005 mg/L EPA 200.7 or 6010D Mercury 0.00005 mg/L EPA 245.1 or 7470A Molybdenum 0.001 mg/L EPA 200.8 or 6020B Nickel 0.001 mg/L EPA 200.8 or 6020B Selenium 0.001 mg/L EPA 200.8 or 6020B Strontium 0.005 mg/L EPA 200.7 or 6010D Thallium (low level)0.0002 mg/L EPA 200.8 or 6020B Vanadium (low level)0.0003 mg/L EPA 200.8 or 6020B Zinc 0.005 mg/L EPA 200.7 or 6010D Radium 226 1 pCi/L EPA 903.1 Modified Radium 228 1 pCi/L EPA 904.0/SW846 9320 Modified Uranium (233, 234, 236, 238)Varies by isotope µg/mL SW846 3010A/6020A Alkalinity (as CaCO3)5 mg/L SM 2320B Bicarbonate 5 mg/L SM 2320B Calcium 0.01 mg/L EPA 200.7 Carbonate 5 mg/L SM 2320B Chloride 0.1 mg/L EPA 300.0 or 9056A Fluoride 0.1 mg/L EPA 300.0 or 9056A Magnesium 0.005 mg/L EPA 200.7 or 6010D Potassium 0.1 mg/L EPA 200.7 Sodium 0.05 mg/L EPA 200.7 Sulfate 0.1 mg/L EPA 300.0 or 9056A Sulfide 0.1 mg/L SM 4500 S2 D Total Dissolved Solids 25 mg/L SM 2540C Total Phosphorus 0.05 mg/L EPA 365.1 Total Organic Carbon 0.1 mg/L SM5310C/EPA9060A Total Suspended Solids 5 mg/L SM 2450D Prepared by: HHS Checked by: RHJ Notes: NA indicates not applicable. °C - Degrees Celsius mg/L - Milligrams per liter mV - Millivolts NTU - Nephelometric turbidity unit pCi/L - picocuries per liter RL = reporting limit S.U. - Standard Unit ug/mL - micrograms per milliliter µS/cm = micro-Siemens per centimeter Dissolved and total metals analysis FIELD PARAMETERS INORGANICS RADIONUCLIDES ANIONS/CATIONS/OTHER &< &< &< &< &<&< &< &<&< &< &< &< &<&<&< &< &< &< &< &< &< &<!( LAKE WYLIE ALLEN STEAM STATION COAL PILE INA CTIVE A SH BASIN S-9 GWA-6S/D/DA/BR GWA-7S/D AB-33S/D CP-6S/D CP-5S/D CP-4S/D CP-3S/D CP-2S/D CP-1S/D CCR-9S/D CCR-8S/DCCR-7S/DCCR-6S/D CCR-5S/D CCR-4S/D 600 610 6 2 0 5906 3 0 6406505 8 0 570 6606006 0 0 570 6105906205 8 0 610 5 8 0 590 580580 590 6305906105 8 0 610 6005906 3 0 6205 9 0 6405905905 8 0 610FIG URE 1PROPOSED COAL PILE ASSESSMENTSAMPLE LOCATIONSALLEN STEAM STATIONDUKE ENERGY CAROLINAS, LLCBELMONT, NORTH CAROLINADRAWN BY: K. KINGPROJECT MA NAGER: C. SUTTELLCHECKED BY: L. DRAGO DATE: 05/24/2018 148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE 864-421-9999www.synterracorp.com P:\Duke Energy Progress.1026\00 GIS BASE DATA\Allen\Map_Docs\MISC\ALLEN_PropCoalPile_AssessmentWells05242018.mxd 80 0 80 16040 GRAPHIC SCA LE IN FEET NOTES: PROPOSED WELL AND BORING LOCATIONS ARE APPROXIMATEAND MAY BE ADJUSTED BASED ON ACCESSIBILITY AND FIELDCONDITIONS. 2014 AERIAL ORTHOPHOTOGRAPHY OBTAINED FROM W SP, APRIL2014. DRAWING HAS BEEN SET WITH A PROJECTION OF NORTHCAROLINA STATE PLANE COORDINATE SYSTEM FIPS 3200(NAD83/2011). LEGEND &<PROPOSED COAL PILE ASSESSMENT SOILBORING AND MONITORING W ELL &<EXISTING CCR RULE MONITORING W ELLLOCATION (APPROXIMATE) &<EXISTING CAMA GROUNDW ATERMONITORING WELL LOCATION !(AOW AND SEDIMENT SAMPLE LOCATION APPROXIMATE EXTENT OF COAL PILESTORAGE AREA WASTE BOUNDARY DUKE ENERGY PLANT BOUNDARY TOPOGRAPHIC CONTOURS (10' INTERVAL) TOPOGRAPHIC CONTOURS (2' INTERVAL) TECHNICAL MEMORANDUM P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Coal Pile Assessment Tech Memo Revised.docx Date: Revised June 1, 2018 Submitted January 12, 2018 File: 1026.15.05I To: Bristol Grohol (Duke Energy) Cc: Kathy Webb (SynTerra) From: Judd Mahan Subject: Soil and Groundwater Assessment – Former Coal Pile – Riverbend Steam Station Introduction The initial technical memorandum describing groundwater and soil assessment activities for the Riverbend Steam Station (RBSS or Site) was submitted to the North Carolina Department of Environmental Quality (NC DEQ) in January 2018. In correspondence dated May 4, 2018, NC DEQ approved the planned assessment activities and provided comments to be incorporated. This revised technical memorandum incorporates the NC DEQ comments (see Table 1 for details of the comments and responses). Duke Energy Carolinas, LLC (Duke Energy) owns and operated the RBSS in Mount Holly, NC. The Site encompasses approximately 340.7 acres. RBSS began operation as a coal-fired generating station in 1929 and was retired in April 2013. Coal used for electricity generation was transported to the Site by railroad and stored on approximately 12 acres northeast of the power generation plant. Ash generated by the coal-fired power-generating units was sluiced to ash management areas located northeast of the plant operations. Groundwater and soil assessment activities for the former coal storage area (coal pile) are described herein. Regulatory Background In 2014, The North Carolina General Assembly passed the Coal Ash Management Act (CAMA). CAMA required owners of a coal combustion residuals (CCR) surface impoundment to conduct detailed assessment of site groundwater within and around the CCR surface impoundment. Groundwater monitoring wells were installed near the eastern edge of the former coal pile during CAMA-associated fieldwork. Boron, an inorganic constituent, is commonly used as an indicator of CCR impacts to groundwater. Groundwater sampling results from the wells near the former coal pile did not indicate elevated concentrations of boron. However, the data indicated beryllium in groundwater samples at Soil and Groundwater Assessment – Former Coal Pile Submitted January 12, 2018 Revised June 1, 2018 Duke Energy Carolinas, LLC, Riverbend Steam Station SynTerra Page 2 of 3 P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Coal Pile Assessment Tech Memo Revised.docx concentrations uncharacteristic of other samples from around the coal ash management areas. For these reasons, Duke Energy understands the former coal pile area soils and underlying groundwater to be a potential “secondary source” of inorganic constituents that will be assessed apart from CAMA. Station Description Coal-fired power generation operations began at RBSS in 1929 and ended in April 2013 when the coal-fired units were retired. Coal was transported on-site by rail and offloaded onto the coal pile area where it was stored until burned by the coal-powered energy generating units. The former coal pile area is approximately 12 acres and is located adjacent to the RBSS power house building and the Catawba River. Coal removal from the area was completed in September 2014. Commingled coal and soil material removal was completed in December 2016. A visual inspection was performed to verify commingled coal and soil material was removed. The topography at RBSS generally slopes downward from the south to the Catawba River on the north. The site layout is shown on Figure 1. Coal Pile Area Assessment Objectives Objectives of the coal pile area assessment include the following: Characterize inorganic constituents associated with coal pile area soils Characterize inorganic constituent concentrations in shallow groundwater underlying the coal pile area and along the coal pile area perimeter Compare inorganic constituent concentrations in coal pile area groundwater and site background groundwater Soil Assessment Coal pile area soils will be sampled and analyzed for inorganic parameters to determine if they are a secondary source of coal pile constituents that can leach into underlying groundwater. Soil samples will be collected at proposed monitoring well locations (CPA-1 through CPA-7) as part of well installation activities. Two proposed sample locations (CPA-4 and CPA-5) are within the footprint of the former coal pile (Figure 1). Soil samples will be collected at approximately 2-foot intervals to the top of the groundwater table. An additional soil sample will be collected below the water table within the new well screened intervals. Soil samples will be analyzed for inorganic parameters as listed on Table 2. In addition to proposed monitoring well locations, this work plan has been modified to incorporate three soil borings (SB-1 through SB-3) that will be installed by direct push Soil and Groundwater Assessment – Former Coal Pile Submitted January 12, 2018 Revised June 1, 2018 Duke Energy Carolinas, LLC, Riverbend Steam Station SynTerra Page 3 of 3 P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Coal Pile Assessment Tech Memo Revised.docx technology (DPT) in approximate locations as shown on Figure 1. The proposed soil borings will be installed to total depths dictated by first encounter of either probe refusal or top of groundwater. Sampling intervals and analyses for these proposed borings will be consistent with monitoring well soil assessment as described above. Groundwater Assessment Fourteen coal pile assessment (CPA) groundwater monitoring wells will be installed to characterize coal pile area groundwater. Seven shallow (“S”) and seven deep (“D”) groundwater monitoring wells (CPA-1S/D, CPA-2S/D, CPA-3S/D, CPA-4S/D, CPA- 5S/D, CPA-6S/D, and CPA-7S/D) will be installed as well pairs. Four wells (CPA-4S/D and CPA-5S/D) will be installed within the former coal pile footprint. Proposed approximate CPA well installation locations are shown on Figure 1 and proposed well details are provided as Table 3. Specific well locations may be shifted depending upon access and field conditions at the time of installation. Groundwater samples will be analyzed for inorganic constituents as listed on Table 4. Coal Pile Assessment Report A coal pile assessment report will be prepared once all soil and groundwater sample analytical data is received. The report will include the following components: 1) Site History and Source Characterization 2) Site Geology and Hydrogeology 3) Sampling Results 4) Site Conceptual Model 5) Conclusions and Recommendations ATTACHMENTS: Table 1: Response to NC DEQ Comments – Coal Pile Assessment Work Plan Table 2: Soil Analytical Methods Table 3: Proposed Coal Pile Assessment Soil Samples and Monitoring Wells Table 4: Groundwater Analytical Methods Figure 1: Proposed Monitoring Well Locations Soil and Groundwater Assessment – Former Coal Pile Submitted January 12, 2018 Revised June 1, 2018 Duke Energy Carolinas, LLC, Riverbend Steam Station SynTerra P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Coal Pile Assessment Tech Memo Revised.docx ATTACHMENTS TABLE 1 RESPONSE TO NC DEQ COMMENTS – COAL PILE ASSESSMENT WORK PLAN RIVERBEND STEAM STATION DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC Page 1 of 3 P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Table 1 Response to DEQ Comments- Coal Pile Assessment.docx The Riverbend Steam Station Coal Pile Assessment Work Plan Technical Memorandum was submitted to the North Carolina Department of Environmental Quality Division of Water Resources (Division) in January 2018. NCDEQ approval of the work plan with comments on the submittal was forwarded to Duke Energy on May 04, 2018. The table below includes the NCDEQ comments with a brief summary response and/or the section(s) of the current submittal containing a detailed response. DEQ Comment 1 The coal pile assessment report is expected to contain necessary evaluation and interpretation associated with data collected and not just a presentation of the results of the assessment in a data summary format. This may mean incorporation of groundwater assessment data, coal combustion residuals (CCR) program data, or any other necessary information needed to draw appropriate, technically supportable conclusions. Response Summary The Coal Pile Assessment Report will utilize data collected to achieve the objectives of characterizing inorganic constituents in coal pile area soils and shallow groundwater including comparison with site background concentrations. As suggested, this may include groundwater assessment data and CCR program data collected as part of other assessments at the site. DEQ Comment 2 To assess the vertical extent of impacts in the shallow aquifer, the Division recommends screening the paired deeper wells at an interval of 50-60 feet for this phase. Response Summary As discussed in the conference call between Duke Energy, DEQ, and SynTerra on May 18, 2018, the deeper well at each well pair is intended to monitor the saturated zone of overburden above competent bedrock. Careful observation of core collected at each well pair location, and professional judgement to determine the zone of potential relative high conductivity located above competent bedrock (transition zone) will be used to determine screened intervals. Review of boring logs for nearby existing wells (GWA-3D, GWA-11D, and GWA-12D) indicates that strong to very strong, meta-quartz diorite occurs at depths ranging from 40 to 122 feet. Potential screened intervals for the current assessment are likely to be located at or just above those depths. DEQ Comment 3 Move wells CPA-1S/D, CPA-2S/D, CPA,-3S/D, CPA-6S/D, and CPA-7S/D to the known perimeter of the former coal pile footprint. Response Summary As discussed in the conference call between DEQ, Duke Energy, and SynTerra on May 18, 2018, the distance between the perimeter of the former coal pile footprint and the Catawba River is very limited (approximately 200 feet in several locations). The available locations for monitoring wells are also constrained by steep terrain and wetlands. Therefore as agreed during the call, additional soil borings SB-1 through SB-3 will be added to assess soil at an intermediate distance, and the original proposed well locations will be used for monitoring well installations (see Figure 1). DEQ Comment 4 Install an additional downgradient monitoring well pair between the northern edge of the former coal pile area (between proposed wells CPA-1S/D and CPA-2S/D) and the Catawba River. Table 1 - Response to NC DEQ Comments – Coal Pile Assessment Work Plan June 1, 2018 Duke Energy Carolinas, LLC, Riverbend Steam Station SynTerra Page 2 of 3 P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Table 1 Response to DEQ Comments- Coal Pile Assessment.docx Response Summary As noted in the response for Comment 3, the distance between the former coal pile footprint and the Catawba River is limited and locations available for well installation are constrained by steep topography and wetlands. Additional soil borings SB-1 through SB-3 have been added to address assessment between the coal pile footprint and the downgradient area (see Figure 1). DEQ Comment 5 Samples for radionuclide analysis (Radium 226 and 228 and Total Uranium) shall be collected from the soil and groundwater in the proposed wells and additional well requested above. For soil, one sample per well pair is sufficient. For groundwater, one groundwater sample shall be collected in each well. Response Summary Radionuclide data will be collected for characterization of shallow groundwater. NCDEQ provided concurrence on May 31, 2018 that soil samples for radionuclide data do not need to be taken because there is no background data available for comparison. An email from NCDEQ (S. Lanter) to Duke (B. Grohol) was received on May 31, 2018 acknowledging that "Removal of soil analysis for radionuclides as part of the plans supersedes previous direction given by Division for the Riverbend and Weatherspoon facility Coal Pile Assessment Plan comment letters both dated May 4, 2018." DEQ Comment 6 While sonic drilling has been recommended as the method of installation for the coal pile assessment wells, using sonic drilling for the deeper boreholes may result in complications, therefore, it is recommended traditional drilling methods (i.e., auger, air, etc.) be employed for wells completed in bedrock or partially weathered rock. If sonic drilling is chosen, Duke Energy must ensure that the borehole is properly flushed to remove drilling fluid/cuttings prior to installation of the monitoring well to reduce the likelihood of sediment accumulation in the monitoring well which will cause water quality issues and potentially make development/sampling difficult. These potential complications may result in installation of replacement wells. Response Summary Sonic drilling remains SynTerra’s recommended drilling method for the coal pile assessment. SynTerra provided rationale for the use of sonic drilling techniques in the 2014 CSA Work Plans for the Duke Energy Progress sites. The rationale highlighted the advantages of sonic drilling. Compared to other drilling methods capable of achieving targeted well depths, which includes drilling into partially weathered rock/transition zone, sonic drilling: • Produces continuous cores of unconsolidated and consolidated material with high recovery percentage that can be utilized for soil sampling and for observation to determine appropriate depth intervals for well construction. • Minimizes formation compaction, borehole disturbance and smearing through the use of vibration and slow rotation rates which minimize the skin friction on the outer walls of the tooling. • Improves well construction reliability as well materials are installed within the outer steel casing as it is withdrawn and sonic vibration eliminates the potential for sand bridging. • Requires less drilling fluids, and the fluids are potable water rather than mud slurry. This minimizes the amount drilling fluids and sediment that need to be removed later in the well development process. After installation, the boreholes will be properly flushed/developed to remove fluids and cuttings prior to the installation of the monitoring wells. As recommended by NCDEQ, Duke/SynTerra will consult closely with drillers to use appropriately-sized filter packs and screens. Centralizers will be used in wells to ensure uniform annulus space for the filter packs. Table 1 - Response to NC DEQ Comments – Coal Pile Assessment Work Plan June 1, 2018 Duke Energy Carolinas, LLC, Riverbend Steam Station SynTerra Page 3 of 3 P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Table 1 Response to DEQ Comments- Coal Pile Assessment.docx DEQ Comment 7 Proposed well construction involves submerging well screens below the water table. It is recommended that for shallow wells the screen should not be submerged (intentionally), but should bracket the water table and if necessary extend the screen interval to 15-ft to allow the shallow well to accommodate water table fluctuations. Response Summary The approach for well screen intervals was outlined in a May 18, 2018 email from Duke Energy (J. Toepfer) to NCDEQ (S. Lanter). NCDEQ responded via email (S. Lanter to J. Toepfer) on May 23, 2018, stating “During the May 18, 2018 teleconference concerning Coal Pile Assessment Plans, Duke Energy requested concurrence concerning the proposed technical approach for installing well screens approximately 5 feet below the water table. Based on the supporting rationale presented during the meeting, the Division agrees with the proposed plans for well construction to support the assessment. However, the Division may expect new wells for other scopes of work to have screened intervals installed to bracket the water table.” TABLE 2 SOIL ANALYTICAL METHODS RIVERBEND STEAM STATION DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\ Table 2 Soil Analytical Methods.xlsx Page 1 of 1 INORGANIC COMPOUNDS UNITS METHOD Aluminum mg/kg EPA 6010D Antimony mg/kg EPA 6020B Arsenic mg/kg EPA 6020B Barium mg/kg EPA 6010D Beryllium mg/kg EPA 6010D Boron mg/kg EPA 6010D Cadmium mg/kg EPA 6020B Calcium mg/kg EPA 6010D Chloride mg/kg EPA 9056A Chromium mg/kg EPA 6010C Cobalt mg/kg EPA 6020A Copper mg/kg EPA 6010C Iron mg/kg EPA 6010C Lead mg/kg EPA 6020B Magnesium mg/kg EPA 6010D Manganese mg/kg EPA 6010C Mercury mg/kg EPA 7471 B Molybdenum mg/kg EPA 6010D Nickel mg/kg EPA 6010C Nitrate as Nitrogen mg/kg EPA 9056A pH SU EPA 9045D Potassium mg/kg EPA 6010D Selenium mg/kg EPA 6020B Sodium mg/kg EPA 6010D Strontium mg/kg EPA 6010D Sulfate mg/kg EPA 9056A Thallium (total, low level)mg/kg EPA 6020B Total Organic Carbon mg/kg EPA 9060 Vanadium mg/kg EPA 6020B Zinc mg/kg EPA 6010C Notes: 1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted above. meq/100g - millequivalents per 100 grams mg/kg - Milligrams per kilogram mV - Millivolts S.U. - Standard Unit Prepared by: RBI Checked by: WJW 2. Ash samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045; select ash samples will also be analyzed for leaching potential using SPLP Extraction Method 1312 in conjunction with USEPA Methods 6010/6020. 3. Analytical methods and reporting limits as presented were applicable at time of CSA field implementation in 2015. Analytical methods and reporting limits are updated periodically and applied as appropriate. TABLE 3 PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS RIVERBEND STEAM STATION DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Table 3 - RBSS Proposed Coal Pile Assessment Boring & Well Depths.xlsx Page 1 of 2 Monitoring Well/Soil Boring ID Estimated Well Depth (feet bgs) Soil Sample ID (Estimated Depth Interval in feet bgs) Comments ----CPA-1SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-1SB (5-6)Unsaturated soil sample ----CPA-1SB (8-9)Unsaturated soil sample ----CPA-1SB (11-12)Unsaturated soil sample ----CPA-1SB (14-15)Unsaturated soil sample ----CPA-1SB (17-18)Unsaturated soil sample ----CPA-1SB (20-21)Unsaturated soil sample ----CPA-1SB (23-24)Unsaturated soil sample CPA-1S 35 CPA-1SB (30-31)Soil sample from shallow well screened interval CPA-1D 150 CPA-1SB (145-146)Soil sample from deep well screened interval ----CPA-2SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-2SB (5-6)Unsaturated soil sample ----CPA-2SB (8-9)Unsaturated soil sample ----CPA-2SB (11-12)Unsaturated soil sample ----CPA-2SB (14-15)Unsaturated soil sample ----CPA-2SB (17-18)Unsaturated soil sample ----CPA-2SB (20-21)Unsaturated soil sample ----CPA-2SB (23-24)Unsaturated soil sample CPA-2S 35 CPA-2SB (30-31)Soil sample from shallow well screened interval CPA-2D 150 CPA-2SB (145-146)Soil sample from deep well screened interval ----CPA-3SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-3SB (5-6)Unsaturated soil sample ----CPA-3SB (8-9)Unsaturated soil sample ----CPA-3SB (11-12)Unsaturated soil sample ----CPA-3SB (14-15)Unsaturated soil sample ----CPA-3SB (17-18)Unsaturated soil sample ----CPA-3SB (20-21)Unsaturated soil sample ----CPA-3SB (23-24)Unsaturated soil sample CPA-3S 35 CPA-3SB (30-31)Soil sample from shallow well screened interval CPA-3D 150 CPA-3SB (145-146)Soil sample from deep well screened interval ----CPA-4SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-4SB (5-6)Unsaturated soil sample ----CPA-4SB (8-9)Unsaturated soil sample ----CPA-4SB (11-12)Unsaturated soil sample ----CPA-4SB (14-15)Unsaturated soil sample ----CPA-4SB (17-18)Unsaturated soil sample ----CPA-4SB (20-21)Unsaturated soil sample ----CPA-4SB (23-24)Unsaturated soil sample CPA-4S 35 CPA-4SB (30-31)Soil sample from shallow well screened interval CPA-4D 150 CPA-4SB (145-146)Soil sample from deep well screened interval ----CPA-5SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-5SB (5-6)Unsaturated soil sample ----CPA-5SB (8-9)Unsaturated soil sample ----CPA-5SB (11-12)Unsaturated soil sample ----CPA-5SB (14-15)Unsaturated soil sample ----CPA-5SB (17-18)Unsaturated soil sample ----CPA-5SB (20-21)Unsaturated soil sample ----CPA-5SB (23-24)Unsaturated soil sample CPA-5S 35 CPA-5SB (30-31)Soil sample from shallow well screened interval CPA-5D 150 CPA-5SB (145-146)Soil sample from deep well screened interval TABLE 3 PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS RIVERBEND STEAM STATION DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Table 3 - RBSS Proposed Coal Pile Assessment Boring & Well Depths.xlsx Page 2 of 2 Monitoring Well/Soil Boring ID Estimated Well Depth (feet bgs) Soil Sample ID (Estimated Depth Interval in feet bgs) Comments ----CPA-6SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-6SB (5-6)Unsaturated soil sample ----CPA-6SB (8-9)Unsaturated soil sample ----CPA-6SB (11-12)Unsaturated soil sample ----CPA-6SB (14-15)Unsaturated soil sample ----CPA-6SB (17-18)Unsaturated soil sample ----CPA-6SB (20-21)Unsaturated soil sample ----CPA-6SB (23-24)Unsaturated soil sample CPA-6S 35 CPA-6SB (30-31)Soil sample from shallow well screened interval CPA-6D 150 CPA-6SB (145-146)Soil sample from deep well screened interval ----CPA-7SB (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) ----CPA-7SB (5-6)Unsaturated soil sample ----CPA-7SB (8-9)Unsaturated soil sample ----CPA-7SB (11-12)Unsaturated soil sample ----CPA-7SB (14-15)Unsaturated soil sample ----CPA-7SB (17-18)Unsaturated soil sample ----CPA-7SB (20-21)Unsaturated soil sample ----CPA-7SB (23-24)Unsaturated soil sample CPA-7S 35 CPA-7SB (30-31)Soil sample from shallow well screened interval CPA-7D 150 CPA-7SB (145-146)Soil sample from deep well screened interval --SB-1 (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) --SB-1 (5-6)Unsaturated soil sample --SB-1 (8-9)Unsaturated soil sample --SB-1 (11-12)Unsaturated soil sample --SB-1 (14-15)Unsaturated soil sample --SB-1 (17-18)Unsaturated soil sample --SB-1 (20-21)Unsaturated soil sample --SB-1 (23-24)Unsaturated soil sample --SB-2 (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) --SB-2 (5-6)Unsaturated soil sample --SB-2 (8-9)Unsaturated soil sample --SB-2 (11-12)Unsaturated soil sample --SB-2 (14-15)Unsaturated soil sample --SB-2 (17-18)Unsaturated soil sample --SB-2 (20-21)Unsaturated soil sample --SB-2 (23-24)Unsaturated soil sample --SB-3 (2-3) Near-surface unsaturated soil sample (water table ~25 feet bgs) --SB-3 (5-6)Unsaturated soil sample --SB-3 (8-9)Unsaturated soil sample --SB-3 (11-12)Unsaturated soil sample --SB-3 (14-15)Unsaturated soil sample --SB-3 (17-18)Unsaturated soil sample --SB-3 (20-21)Unsaturated soil sample --SB-3 (23-24)Unsaturated soil sample Prepared by: JDM Checked by: WJW Notes: bgs = below ground surface ~ = Approximately SynTerra recommends rotosonic drilling methods for boring and well installation. Continuous cores from sonic drilling provide sufficient material for soil sampling and lithologic description. Estimated well and soil sample depths based on data from the GWA-3, GWA-11 and GWA-12 well clusters. Number of soil samples shown is approximate. A shallower water table will result in fewer samples, and a deeper water table will result in additional samples. SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet. SB-3 SB-1 SB-2 TABLE 4 GROUNDWATER ANALYTICAL METHODS RIVERBEND STEAM STATION DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC P:\Duke Energy Carolinas\15. Riverbend\05.EHS CAMA Compliance Support\Coal Pile Assessment\Work Plan Revision May 2018\Table 4 - GW Analytical Methods.xlsx Page 1 of 1 PARAMETER RL UNITS METHOD pH NA SU Field Water Quality Meter Specific Conductance NA µS/cm Field Water Quality Meter Temperature NA ºC Field Water Quality Meter Dissolved Oxygen NA mg/L Field Water Quality Meter Oxidation Reduction Potential NA mV Field Water Quality Meter Turbidity NA NTU Field Water Quality Meter Ferrous Iron NA mg/L Field Test Kit Aluminum 0.005 mg/L EPA 200.7 or 6010D Antimony 0.001 mg/L EPA 200.8 or 6020B Arsenic 0.001 mg/L EPA 200.8 or 6020A Barium 0.005 mg/L EPA 200.7 or 6010C Beryllium 0.001 mg/L EPA 200.8 or 6020A Boron 0.05 mg/L EPA 200.7 or 6010C Cadmium 0.001 mg/L EPA 200.8 or 6020A Chromium 0.001 mg/L EPA 200.8 or 6010C Cobalt 0.001 mg/L EPA 200.8 or 6020A Copper 0.001 mg/L EPA 200.8 or 6020B Iron 0.01 mg/L EPA 200.7 or 6010C Lead 0.001 mg/L EPA 200.8 or 6020A Manganese 0.005 mg/L EPA 200.7 or 6010C Mercury (low level)0.005 ng/L 1631 ONLY Molybdenum 0.001 mg/L EPA 200.8 or 6020B Nickel 0.001 mg/L EPA 200.8 or 6020B Phosphorus 0.005 mg/L EPA 365.1 Selenium 0.001 mg/L EPA 200.8 or 6020A Strontium 0.005 mg/L EPA 200.7 or 6010C Thallium (low level)0.0002 mg/L EPA 200.8 or 6020A Vanadium (low level)0.0003 mg/L EPA 200.8 or 6020A Zinc 0.005 mg/L EPA 200.7 or 6010C Radium 226 1 pCi/L EPA 903.1 Modified Radium 228 1 pCi/L EPA 904.0/SW846 9320 Modified Uranium (233, 234, 236, 238)Varies by isotope µg/mL SW846 3010A/6020A Alkalinity (as CaCO3)5 mg/L SM 2320B Bicarbonate 5 mg/L SM 2320 Calcium 0.01 mg/L EPA 200.7 Carbonate 5 mg/L SM 2320 Chloride 0.1 mg/L EPA 300.0 or 9056A Magnesium 0.005 mg/L EPA 200.7 Methane 0.01 mg/L RSK 175 Nitrate as Nitrogen 0.01 mg-N/L EPA 353.2 Potassium 0.1 mg/L EPA 200.7 Sodium 0.05 mg/L EPA 200.7 Sulfate 0.1 mg/L EPA 300.0 or 9056A Sulfide 0.1 mg/L SM4500S2-D Total Dissolved Solids 25 mg/L SM 2540C Total Organic Carbon 0.1 mg/L SM 5310C/EPA9060A Total Suspended Solids 2.5 mg/L SM 2450D Prepared by: RBI Checked by: WJW Notes: ºC - Degrees Celsius µS/cm = micro-Siemens per centimeter mg/L - Milligrams per liter mg - N/L - Milligrams nitrogen per liter mV - Millivolts NA - Not analyzed NTU - Nephelometric turbidity unit pCi/L - picocuries per liter RL = reporting limit S.U. - Standard Unit ug/mL - micrograms per milliliter 2.Analytical methods and reporting limits as presented were applicable at time of CSA field implementation in 2015.Analytical methods and reporting limits are updated periodically and applied as appropriate. INORGANICS FIELD PARAMETERS 1. Select constituents will be analyzed for total and dissolved concentrations. ANIONS/CATIONS RADIONUCLIDES &< &< &< &< &< &< &< &< &< &< &<&< &< &< &<&< &<&< &<&<&< &<&<&<&<&< &<&<&< &<&< &<&< &<&< &<&< &< &< &<&< &<&< &<&< &<&< &<&< &< &<&< &<&<&<&<&<&<&<&<&< &<&<&< &<&< &<&<&< &<&< &<&< &<&<&< &<&< &<&<&< &<&< &<&< &<&< &<&< &<&< &<&< &<&< &<&<&< &<&<&< &< !( !( !( !(!( !( !( ") ") ") BG-4S /D/BR MW-9 /BR AB-2D MW-1 5D/BR BG-5D/BR MW-8 S/I/D GWA-21 S/D/BR MW-11SR/DR MW-13 MW-10 MW-14 OB -1 OB -2 GAT E 7 AB-1S/D AB-2S/D AB-3S /D/BR AB-5S /SL/D AB-6S /BRU AB-7S /I/D AB-8S/D BG-1S/D BG-2S /D/BR BG-3S/D C-1S /BRU C-2S/D GWA-10 S/BRU GWA-11S/D GWA-12S/D GWA-14S GWA-1S/BRU GWA-20 S/D/BR GWA-22 S/D/BR-A GWA-23 S/D/BR GWA-2S/BR/BRU GWA-3S-A/D GWA-4S/D/BR GWA-5S/D GWA-6S/D GWA-7S/D/BR GWA-8S/D GWA-9S/D/BR MW-1 S/D MW-2 S/D MW-3 S/D MW-4 S/D MW-5 S/D MW-6 S/D MW-7 S/D/BRCPA-5S/D CPA -7S/D CPA -6S/D CPA -1S/D CPA -4S/D CPA -3S/D CPA -2S/D SB-1 SB-2 SB-3 FIGURE 1PROPOSED MONITORING W ELL LOCATIONSCOAL P ILE AS SESSMENTRIVERBEND ST EAM STATIONDUKE ENE RGY CAROLINAS, LLCMOUNT HOLLY, NORTH CAROLINADRAWN BY: A. FEIGLPROJECT MANAGER: J. MAHANCHECKED BY: B. WYLIE DATE: 05/30/2018 148 RIVER STREET, SUITE 220GREENVILLE, S OUTH CAROLINA 29601PHONE 864-421-9999www.synterracorp.com P:\Duke Energy Progress.1026\00 GIS BASE DATA\Riv erbend\MapDocs\Vetting\CoalPileAssess\Riverbend_CoalPileAssess_20180530.mxd 300 0 300 600150 GRAPHIC SC ALE IN FEET LE GEND !(PROPOS ED COAL PILE ASSESSMENTMONITORING WE LL LOCATION ")SOIL B ORIN G LOCATIONS &<EXISTING M ONITORIN G WELL LOCATION &<OB SE RVATION WELL LOCATION WE TLAND S [AMEC] CULTURAL AREA RAILROAD TRA NS MISS ION LINE APP ROXIMATE WASTE BOUNDARY DUKE P OWER PLA NT BOUNDARY NOTES: PROPOSED WELL L OCATI ONS SHOW N ARE APPROXIMATED.EXACT WELL LOCATIONS WIL L BE DETERMINED BASED ONACCESS AND FIELD CONDITIONS AT THE TIME OF W ELLINSTALLATION. ALL BOUNDARIES ARE APPROXIMATE. SITE AERIAL ORTHOPHOTOGRAPHY OBTAINED FROMMECKLENBURG COUNTY GIS, DATED 2 017. ADDITIONAL AERIALORTHOPHOTOGRAPHY OBTAINED FROM W SP, 10/30/2015. DRAWING HAS BEEN SET WIT H A PROJECTION OF NORTHCAROLINA STATE PLANE COORDI NATE SYSTEM FIPS 3200 CATAWBA RIVERCATAWBA RIVER FORM ERCOAL P ILE ASH BA SINSECONDARY CELL ASH BA SINPRIMARY CELL ASH S TORAGE CINDERSTORAGE TECHNICAL MEMORANDUM P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Weatherspoon Coal Pile Asmt Tech Memo.docx DATE: Revised June 5, 2018 File: 1026.109.44 Submitted January 12, 2018 To: Bryson Sheetz (Duke Energy) Cc: Kathy Webb (SynTerra) From: Ted Volskay Subject: Coal Pile Area Assessment––W.H. Weatherspoon Power Plant The initial technical memorandum describing groundwater and soil assessment activities for the W.H. Weatherspoon Power Plant (Weatherspoon, Plant, or Site) was submitted to the North Carolina Department of Environmental Quality (NC DEQ) in January 2018. In correspondence dated May 4, 2018, NC DEQ approved the planned assessment activities and provided comments to be incorporated. This revised technical memorandum incorporates the NC DEQ comments (see Table 1 for details of the comments and responses). Duke Energy Progress, LLC (Duke Energy) owns and operated the W.H. Weatherspoon Power Plant (Plant or Site) in Lumberton, NC. The Site encompasses approximately 835 acres. Coal-fired power generation operations began in 1949 and ended in October 2011 when the coal-fired units were retired. Coal used for electricity generation was transported to the Site by railroad and stored on approximately 6.5 acres southeast of the power generation plant. Groundwater and soil assessment activities for the coal storage area (coal pile) are described herein. Regulatory Background In 2014, The North Carolina General Assembly passed the Coal Ash Management Act (CAMA). CAMA required owners of a coal combustion residuals (CCR) surface impoundment to conduct detailed assessment of site groundwater within and around the CCR surface impoundment. Groundwater monitoring well AW-2S was installed near the southeastern edge of the coal pile area during CAMA-associated fieldwork. Inorganic analysis of groundwater samples collected from well AW-2S detected constituents (aluminum, beryllium, cadmium, cobalt, copper, nickel, selenium, and zinc) at concentrations uncharacteristic of Plant background groundwater or groundwater underlying the coal ash basin. Boron, an indicator constituent of CCR impacts to groundwater, has been detected in Coal Pile Area Assessment Tech Memo Submitted January 12, 2018, Revised June 5, 2018 W.H. Weatherspoon Power Plant Page 2 of 4 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Weatherspoon Coal Pile Asmt Tech Memo.docx AW-2S groundwater samples at relatively low concentrations (<165 ug/L). For these reasons, Duke Energy understands the coal pile area soils and underlying groundwater to be a potential “secondary source” of inorganic constituents that will be assessed apart from CAMA. Station Description Coal was transported on-site by rail and offloaded onto the coal pile area where it was stored until burned by coal-powered energy generating units. The coal-fired power plants have since been demolished and coal is no longer stored onsite. The coal pile area is approximately 6.5 acres and is located adjacent to and southeast of the former coal powered power plants (Figure 1). A 225 acre cooling pond is located adjacent to and southwest of the former coal powered power plants and the coal pile area. The topography at the coal pile area generally slopes toward the south and southeast. Surface water that falls on the northeastern half of the coal pile area drains to a low lying area along the southeast and eastern perimeter of the coal pile area. Surface water that collects in this area flows into a drainage pipe beyond the western perimeter of the coal stockpile area. The drainage pipe transports surface water underneath the former rail spur and the discharge flows into a wetland located between the coal pile area, ash basin, and cooling pond. Surface water on the southwestern half of the coal pile area drains toward the south and southwest and into the cooling pond. Coal Pile Area Assessment Objectives Objectives of the coal pile area assessment include the following: Characterize inorganic constituents associated with coal pile area soils Compare inorganic constituent concentrations in coal pile area soils and site background soils Characterize inorganic constituent concentrations in groundwater underlying the coal pile area and just beyond the coal pile area perimeter Compare inorganic constituent concentrations in coal pile area groundwater and site background groundwater Soil Assessment Coal pile area soils will be sampled and analyzed for inorganic parameters to determine if they are a secondary source of coal pile constituents that can leach into underlying groundwater. Soil samples will be collected from 17 soil boring locations (CPA-SB1 through CPA-SB17) presented in Figure 1 using a GeoProbe© rig. Soil samples will be collected from the near ground surface (2 to 3 foot) and at approximately 2-foot intervals to the top of the groundwater table. Soil samples will be analyzed for Coal Pile Area Assessment Tech Memo Submitted January 12, 2018, Revised June 5, 2018 W.H. Weatherspoon Power Plant Page 3 of 4 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Weatherspoon Coal Pile Asmt Tech Memo.docx inorganic parameters consistent with assessment of areas used for coal and CCR management (Table 2). Continuous soil cores will be collected from the ground surface to the first confining unit at each proposed well pair and at CPA-2I using a GeoProbe© rig. The continuous soil cores will serve four purposes: Continuous soil cores will be used to document the underlying stratigraphy Continuous soil cores will be used to identify the zones where shallow (Surficial sands) and intermediate (Yorktown Formation) wells will be screened Soil samples will be collected from a depth corresponding to the middle of the shallow and intermediate well screens Documentation of the underlying stratigraphy (#1 above) will provide the flexibility of using different types of drill rigs (e.g., rotosonic, hollow-stem auger) to install the shallow and deep coal pile assessment wells Groundwater Assessment Fifteen coal pile assessment (CPA) groundwater monitoring wells will be installed to characterize coal pile area groundwater. Seven shallow (“S”) and seven intermediate (“I”) groundwater monitoring wells (CPA-1S/I, CPA-3S/I, CPA-4S/I, CPA-5S/I, CPA- 6S/I, CPA-7S/I, and CPA-8S/I) will be installed as well pairs and CPA-2I will be installed as a single intermediate well. Proposed CPA well installation locations are shown on Figure 1 and proposed well details are provided in Table 3. Groundwater samples will be analyzed for the field parameters (e.g., pH, conductivity, and turbidity) and inorganic constituents consistent with assessment of areas used for coal and CCR management Table 4. Existing fuel oil remediation wells MW-2 and MW-4 will be included in coal pile groundwater assessment. Both wells are located within the coal pile area footprint. Well MW-2 is located southeast of the above ground storage tank and well MW-4 is located south of the above ground storage tank (Figure 1). Both wells have 10 ft. long well screens and are screened across the water table. The bottom of the MW-2 well screen is 13.0 ft. below ground surface and The bottom of the MW-2 well screen is 12.7 ft. below ground surface. Coal Pile Assessment Report A coal pile assessment report will be prepared once all soil and groundwater sample analytical data is received. The report will include the following components: Coal Pile Area Assessment Tech Memo Submitted January 12, 2018, Revised June 5, 2018 W.H. Weatherspoon Power Plant Page 4 of 4 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Weatherspoon Coal Pile Asmt Tech Memo.docx 1) Site History and Source Characterization 2) Site Geology and Hydrogeology 3) Sampling Results (two rounds of groundwater sampling) 4) Site Conceptual Model 5) Conclusions and Recommendations Coal Pile Area Assessment Tech Memo Submitted January 12, 2018, Revised June 5, 2018 W.H. Weatherspoon Power Plant Page 5 of 4 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Weatherspoon Coal Pile Asmt Tech Memo.docx Attachments: Figure 1: Proposed Monitoring Well & Soil Boring Location Map Table 1: Response To NC DEQ Comments - Coal Pile Assessment Work Plan Table 2: Soil Analytical Methods Table 3: Proposed Coal Pile Assessment Soil Samples and Monitoring Wells Table 4: Groundwater Analytical Methods Coal Pile Area Assessment Tech Memo Submitted January 12, Revised June 5, 2018 W.H. Weatherspoon Power Plant P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Weatherspoon Coal Pile Asmt Tech Memo.docx ATTACHMENTS 12/18/2017 3:35 PMP:\Duke Energy Progress.1026\09.WEATHERSPOON PLANT\09.COAL PILE ASSESSMENT\DWG\DE WEATHERSPOON CPA BASE MAP 2017-12-18.dwg148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE 864-421-9999www.synterracorp.comPROJECT MANAGER:LAYOUT:DRAWN BY:TED VOLSKAYDATE:JOHN CHASTAINFIG 1 (PROP MW & SB LOC MAP)12/18/2017FORMER SMOKE STACKFIGURE 1PROPOSED MONITORING WELL & SOILBORING LOCATION MAPW.H. WEATHERSPOON POWER PLANT491 POWER PLANT RDLUMBERTON, NORTH CAROLINACSA MONITORING WELL (SURVEYED)MONITORING WELL (APPROXIMATE)LEGENDMW-3AW-2SAW-2DAW-2I50050100GRAPHIC SCALEIN FEETMW-53IMW-53DMW-5MW-4MW-3MW-1CW-01CW-01COMPLIANCE MONITORING WELL (SURVEYED)SOURCES:OCTOBER 26, 2016 AERIAL PHOTOGRAPH OBTAINED FROM GOOGLE EARTH PROEXTENT OF COAL STOCKPILE (COMPOSITE)COAL STOCKPILE ASSESSMENT AREAMW-2AW-2DRW-05RW-06RW-03RW-02RW-04RW-01RW-00RW-06FUEL OIL RECOVERY WELL (APPROXIMATE)NO. 2 FUEL OIL AST500,000 GALRETIRED COAL PLANTC T P LAN T CT PLANTOIL/WATER SEPARATORCPA-8SCPA-8ICPA-7SCPA-7ICPA-4SCPA-4ICPA-5SCPA-5ICPA-6SCPA-6ICPA-1SCPA-1ICPA-2ICPA-3SCPA-3ICPA-SB5CPA-SB4CPA-SB3CPA-SB2CPA-SB8CPA-SB7CPA-SB1CPA-SB6CPA-SB17CPA-SB16CPA-SB15CPA-SB14CPA-SB11FUEL OIL UNLOADING STATIONFUEL OIL PIPE LINECPA-SB10CPA-SB13CPA-SB12CPA-SB9CPA-SB8CPA-SB12CPA-2IPROPOSED SOIL BORING TO THE TOP OF THE CONFINING LAYERPROPOSED SOIL BORING TO THE TOP OF THE WATER TABLEPROPOSED COAL PILE ASSESSMENT MONITORING WELLFENCEFORMER RAILROAD LINE130128 13 0 128128 1 26 124122120 Page 1 of 3 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Table 1 Responses to NCDEQ Comments.docx TABLE 1 RESPONSE TO NC DEQ COMMENTS - COAL PILE ASSESSMENT WORK PLAN W.H. WEATHERSPOON POWER PLANT DUKE ENERGY PROGRESS, LLC, LUMBERTON, SC The W.H. Weatherspoon Coal Pile Assessment Work Plan Technical Memorandum was submitted to the North Carolina Department of Environmental Quality (NC DEQ) Division of Water Resources in January 2018. NC DEQ’s approval of the work plan, with comments on the submittal, was forwarded to Duke Energy on May 4, 2018. Table 1 (below) includes the NC DEQ comments with a brief summary response and/or the section(s) of the current submittal containing a detailed response. NC DEQ Comment 1 The coal pile assessment report is expected to contain necessary evaluations and interpretations associated with collected data and not just present the results of the assessment. This may mean incorporation of groundwater assessment data, coal combustion residuals (CCR) program data, or any other necessary information needed to draw appropriate, technically supportable conclusions. Response Summary Data will be collected and used in the coal pile assessment report to achieve the objectives of characterizing inorganic constituents in coal pile area soils and groundwater, including comparison with site background concentrations. As suggested, this may include CAMA and CCR program data and other available and relevant data associated with improvement projects in the vicinity of the coal pile. NC DEQ Comment 2 The following technical direction shall be incorporated into the coal pile assessment: With the exception of CPA-1S/lD, move the remaining proposed coal pile assessment wells to the known or assumed perimeter of the former coal pile footprint. Response Summary The specific locations of proposed coal pile assessment groundwater monitoring wells contained in the W.H. Weatherspoon Coal Pile Assessment Work Plan Technical Memorandum was addressed during the May 18 conference call between Duke Energy and NCDEQ. NCDEQ said that proposed coal pile assessment groundwater monitoring well locations were acceptable as proposed in the W.H. Weatherspoon Coal Pile Assessment Work Plan Technical Memorandum. NC DEQ Comment 3 The following technical direction shall be incorporated into the coal pile assessment: • Samples for radionuclide analysis (Radium 226 and 228 and Total Uranium) shall be collected from soil and groundwater in the proposed soil borings and wells. For soil, one sample per boring or well pair is sufficient. For groundwater, one groundwater sample shall be collected in each well. Table 1 - Response to NC DEQ Comments – Coal Pile Assessment Work Plan June 5, 2018 Duke Energy Progress, LLC, W. H. Weatherspoon Power Plant SynTerra Page 2 of 3 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Table 1 Responses to NCDEQ Comments.docx Response Summary • One groundwater sample per groundwater monitoring well will be analyzed for Radium 226, Radium 228, and Total Uranium. • NCDEQ provided concurrence on May 31, 2018 that soil samples for radionuclide data do not need to be taken because there is no background data available for comparison. An email from NCDEQ (S. Lanter) to Duke (B. Grohol) was received on May 31, 2018 acknowledging that "Removal of soil analysis for radionuclides as part of the plans supersedes previous direction given by Division for the Riverbend and Weatherspoon facility Coal Pile Assessment Plan comment letters both dated May 4, 2018 • The analytical methods for these analytes are included in Table 4 (formerly Table 3). NC DEQ Comment 4 The following revisions to the coal pile assessment plan are recommended: While sonic drilling is proposed as a potential method of installation for the coal pile assessment wells, using sonic drilling may result in complications, therefore, it is recommended traditional drilling methods (i.e., auger, air, etc.) be employed. If sonic drilling is chosen, Duke Energy must ensure that the borehole is properly flushed to remove drilling fluid/cuttings prior to installation of the monitoring well to reduce the likelihood of sediment accumulation in the monitoring well which will cause water quality issues and potentially make development/sampling difficult. These potential complications may result in installation of replacement wells. Response Summary SynTerra considers rotosonic or hollow stem auger drilling technologies to be acceptable drilling methods for the installation of W.H. Weatherspoon coal pile assessment groundwater monitoring wells. However, SynTerra will recommend that the hollow stem auger drilling technique be used to install groundwater monitoring wells proposed in the Coal Pile Assessment Work Plan Technical Memorandum. NC DEQ Comment 5 The following revisions to the coal pile assessment plan are recommended: Proposed well construction involves submerging well screens below the water table. It is recommended that for shallow wells the screen should not be submerged (intentionally), but should bracket the water table and if necessary extend the screen interval to 15-ft to allow the shallow well to accommodate water table fluctuations. Table 1 - Response to NC DEQ Comments – Coal Pile Assessment Work Plan June 5, 2018 Duke Energy Progress, LLC, W. H. Weatherspoon Power Plant SynTerra Page 3 of 3 P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Table 1 Responses to NCDEQ Comments.docx Response Summary To date, all CAMA and CCR groundwater monitoring wells installed at W.H. Weatherspoon have been designed so that the well screen is approximately 5 or more feet below the water table. Duke Energy continues to recommend well installation with top of screen approximately 5 feet below the water table. That approach is consistent with the approach for shallow well installation proposed in the Groundwater Assessment Work Plans for DEP sites submitted to DEQ in December 2014 and implemented in subsequent CAMA-related well installations. This approach for well screen intervals was outlined in a May 18, 2018, email from Duke Energy (J. Toepfer) to NCDEQ (S. Lanter). NCDEQ responded via email (S. Lanter to J. Toepfer) on May 23, 2018, stating “During the May 18, 2018 teleconference concerning Coal Pile Assessment Plans, Duke Energy requested concurrence concerning the proposed technical approach for installing well screens approximately 5 feet below the water table. Based on the supporting rationale presented during the meeting, the Division agrees with the proposed plans for well construction to support the assessment. However, the Division may expect news wells for other scopes of work to have screened intervals installed to bracket the water table.” Duke Energy recommends sampling existing fuel oil remediation wells MW-2 and MW-4. Both wells are located within the coal pile area footprint. Well MW-2 is located southeast of the above ground storage tank and well MW-4 is located south of the above ground storage tank (Figure 1). Both wells have 10 ft. long well screens and are screened across the water table. The bottom of the MW-2 well screen is 13.0 ft. below ground surface and The bottom of the MW-2 well screen is 12.7 ft. below ground surface. NC DEQ Comment 6 The assessment of all other potential sources of groundwater contamination that are located within the footprint of or that may contribute to the groundwater plumes associated with impoundment should also be included as part of the updated Comprehensive Site Assessment. Response Summary Other potential sources of groundwater contamination that are located within the footprint of or that may contribute to the groundwater plumes associated with impoundment will be included as part of the updated Comprehensive Site Assessment. TABLE 2 SOIL ANALYTICAL METHODS W.H. WEATHERSPOON POWER PLANT DUKE ENERGY PROGRESS, LLC, LUMBERTON, NC P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\ Table 2 Weatherspoon Coal Pile Asmt Tech Memo Page 1 of 1 INORGANIC COMPOUNDS ANALYTICAL METHODS Aluminum EPA 6010D Antimony EPA 6020B Arsenic EPA 6020A Barium EPA 6010C Beryllium EPA 6020B Boron EPA 6010C Cadmium EPA 6020A Calcium EPA 6010C Chloride EPA 9056A Chromium EPA 6010C Cobalt EPA 6020A Copper EPA 6010C Iron EPA 6010C Lead EPA 6020A Magnesium EPA 6010C Manganese EPA 6010C Mercury EPA 7471B Molybdenum EPA 6010C Nickel EPA 6010C Nitrate as Nitrogen EPA 9056A pH EPA 9045D Potassium EPA 6010C Selenium EPA 6020A Sodium EPA 6010C Strontium EPA 6010C Sulfate EPA 9056A Thallium EPA 6020A Total Organic Carbon EPA 9060 Vanadium EPA 6020A Zinc EPA 6010C Prepared by: RBI Checked by: SRW/TCP/VTV Notes: EPA - United States Environmental Protection Agency TABLE 3 PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS W.H. WEATHERSPOON POWER PLANT DUKE ENERGY PROGRESS, LLC, LUMBERTON, NC P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Table 3 Weatherspoon Coal Pile Asmt Tech Memo Page 1 of 2 Monitoring Well ID Estimated Well Depth (feet bgs) Soil Sample ID (Estimated Depth Interval in feet bgs) Comments ----CPA-SB1 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB1 (5-6)Unsaturated soil sample ----CPA-SB1 (8-9)Unsaturated soil sample ----CPA-SB1 (11-12)Unsaturated soil sample ----CPA-SB1 (14-15)Unsaturated soil sample ----CPA-SB1 (17-18)Unsaturated soil sample CPA-1S 35 CPA-SB1 (29-31)Soil sample from shallow well screened interval CPA-1I 65 CPA-SB1 (59-61)Soil sample from deep well screened interval ----CPA-SB2 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB2 (5-6)Unsaturated soil sample ----CPA-SB2 (8-9)Unsaturated soil sample ----CPA-SB2 (11-12)Unsaturated soil sample ----CPA-SB2 (14-15)Unsaturated soil sample ----CPA-SB2 (17-18)Unsaturated soil sample CPA-2I 65 CPA-SB2 (59-61)Soil sample from deep well screened interval ----CPA-SB3 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB3 (5-6)Unsaturated soil sample ----CPA-SB3 (8-9)Unsaturated soil sample ----CPA-SB3 (11-12)Unsaturated soil sample ----CPA-SB3 (14-15)Unsaturated soil sample ----CPA-SB3 (17-18)Unsaturated soil sample CPA-3S 35 CPA-SB3 (29-31)Soil sample from shallow well screened interval CPA-3I 65 CPA-SB3 (59-61)Soil sample from deep well screened interval ----CPA-SB4 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB4 (5-6)Unsaturated soil sample ----CPA-SB4 (8-9)Unsaturated soil sample ----CPA-SB4 (11-12)Unsaturated soil sample ----CPA-SB4 (14-15)Unsaturated soil sample ----CPA-SB4 (17-18)Unsaturated soil sample CPA-4S 35 CPA-SB4 (29-31)Soil sample from shallow well screened interval CPA-4I 65 CPA-SB4 (59-61)Soil sample from deep well screened interval ----CPA-SB5 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB5 (5-6)Unsaturated soil sample ----CPA-SB5 (8-9)Unsaturated soil sample ----CPA-SB5 (11-12)Unsaturated soil sample ----CPA-SB5 (14-15)Unsaturated soil sample ----CPA-SB5 (17-18)Unsaturated soil sample CPA-5S 35 CPA-SB5 (29-31)Soil sample from shallow well screened interval CPA-5I 65 CPA-SB5 (59-61)Soil sample from deep well screened interval ----CPA-SB6 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB6 (5-6)Unsaturated soil sample ----CPA-SB6 (8-9)Unsaturated soil sample ----CPA-SB6 (11-12)Unsaturated soil sample ----CPA-SB6 (14-15)Unsaturated soil sample ----CPA-SB6 (17-18)Unsaturated soil sample CPA-6S 35 CPA-SB6 (29-31)Soil sample from shallow well screened interval CPA-6I 65 CPA-SB6 (59-61)Soil sample from deep well screened interval ----CPA-SB7 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB7 (5-6)Unsaturated soil sample ----CPA-SB7 (8-9)Unsaturated soil sample ----CPA-SB7 (11-12)Unsaturated soil sample ----CPA-SB7 (14-15)Unsaturated soil sample ----CPA-SB7 (17-18)Unsaturated soil sample CPA-7S 35 CPA-SB6 (29-31)Soil sample from shallow well screened interval CPA-7I 65 CPA-SB6 (59-61)Soil sample from deep well screened interval ----CPA-SB8 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB8 (5-6)Unsaturated soil sample ----CPA-SB8 (8-9)Unsaturated soil sample ----CPA-SB8 (11-12)Unsaturated soil sample ----CPA-SB8 (14-15)Unsaturated soil sample ----CPA-SB8 (17-18)Unsaturated soil sample CPA-8S 35 CPA-SB8 (29-31)Soil sample from shallow well screened interval CPA-8I 65 CPA-SB8 (59-61)Soil sample from deep well screened interval TABLE 3 PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS W.H. WEATHERSPOON POWER PLANT DUKE ENERGY PROGRESS, LLC, LUMBERTON, NC P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Table 3 Weatherspoon Coal Pile Asmt Tech Memo Page 2 of 2 Monitoring Well ID Estimated Well Depth (feet bgs) Soil Sample ID (Estimated Depth Interval in feet bgs) Comments ----CPA-SB9 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB9 (5-6)Unsaturated soil sample ----CPA-SB9 (8-9)Unsaturated soil sample ----CPA-SB9 (11-12)Unsaturated soil sample ----CPA-SB9 (14-15)Unsaturated soil sample ----CPA-SB9 (17-18)Unsaturated soil sample ----CPA-SB10 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB10 (5-6)Unsaturated soil sample ----CPA-SB10 (8-9)Unsaturated soil sample ----CPA-SB10 (11-12)Unsaturated soil sample ----CPA-SB10 (14-15)Unsaturated soil sample ----CPA-SB10 (17-18)Unsaturated soil sample ----CPA-SB11 (2-31 Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB11 (5-6)Unsaturated soil sample ----CPA-SB11 (8-9)Unsaturated soil sample ----CPA-SB11 (11-12)Unsaturated soil sample ----CPA-SB11 (14-15)Unsaturated soil sample ----CPA-SB11 (17-18)Unsaturated soil sample ----CPA-SB12 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB12 (5-6)Unsaturated soil sample ----CPA-SB12 (8-9)Unsaturated soil sample ----CPA-SB12 (11-12)Unsaturated soil sample ----CPA-SB12 (14-15)Unsaturated soil sample ----CPA-SB12 (17-18)Unsaturated soil sample ----CPA-SB13 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB13 (5-6)Unsaturated soil sample ----CPA-SB13 (8-9)Unsaturated soil sample ----CPA-SB13 (11-12)Unsaturated soil sample ----CPA-SB16 (14-15)Unsaturated soil sample ----CPA-SB13 (17-18)Unsaturated soil sample ----CPA-SB14 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB14 (5-6)Unsaturated soil sample ----CPA-SB14 (8-9)Unsaturated soil sample ----CPA-SB14 (11-12)Unsaturated soil sample ----CPA-SB14 (14-15)Unsaturated soil sample ----CPA-SB14 (17-18)Unsaturated soil sample ----CPA-SB15 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB15 (5-6)Unsaturated soil sample ----CPA-SB15 (8-9)Unsaturated soil sample ----CPA-SB15 (11-12)Unsaturated soil sample ----CPA-SB15 (14-15)Unsaturated soil sample ----CPA-SB15 (17-18)Unsaturated soil sample ----CPA-SB16 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB16 (5-6)Unsaturated soil sample ----CPA-SB16 (8-9)Unsaturated soil sample ----CPA-SB16 (11-12)Unsaturated soil sample ----CPA-SB16 (14-15)Unsaturated soil sample ----CPA-SB16 (17-18)Unsaturated soil sample ----CPA-SB17 (2-3)Unsaturated soil sample (water table <20 feet bgs) ----CPA-SB17 (5-6)Unsaturated soil sample ----CPA-SB17 (8-9)Unsaturated soil sample ----CPA-SB17 (11-12)Unsaturated soil sample ----CPA-SB17 (14-15)Unsaturated soil sample ----CPA-SB17 (17-18)Unsaturated soil sample Prepared by: VTV Checked by: KLS Notes: bgs = below ground surface ~ = Approximately SynTerra recommends rotosonic or hollow-stem auger drilling methods for boring and well installation. Continuous cores from GeoProbe drilling provide sufficient material for soil sampling and lithologic description. Estimated well and soil sample depths based on data from the AW-2S, CW-1, CCR-105 and CCR-106 well clusters. Number of soil samples shown is approximate. A shallower water table will result in fewer samples, and a deeper water table will result in additional samples. SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet. TABLE 4 GROUNDWATER ANALYTICAL METHODS W.H. WEATHERSPOON POWER PLANT DUKE ENERGY PROGRESS, LLC, LUMBERTON, NC P:\Duke Energy Progress.1026\109. Weatherspoon Ash Basin GW Assessment Plan\44.EHS Coal Pile Asmt\Tech Memo\Version 5\Table 4 Weatherspoon Coal Pile Asmt Tech Memo Page 1 of 1 PARAMETER RL UNITS METHOD pH NA SU Field Water Quality Meter Specific Conductance NA µS/cm Field Water Quality Meter Temperature NA ºC Field Water Quality Meter Dissolved Oxygen NA mg/L Field Water Quality Meter Oxidation Reduction Potential NA mV Field Water Quality Meter Turbidity NA NTU Field Water Quality Meter Ferrous Iron NA mg/L Field Test Kit Aluminum 0.005 mg/L EPA 200.7 or 6010D Antimony 0.001 mg/L EPA 200.8 or 6020B Arsenic 0.001 mg/L EPA 200.8 or 6020A Barium 0.005 mg/L EPA 200.7 or 6010C Beryllium 0.001 mg/L EPA 200.8 or 6020A Boron 0.05 mg/L EPA 200.7 or 6010C Cadmium 0.001 mg/L EPA 200.8 or 6020A Chromium 0.001 mg/L EPA 200.8 or 6010C Cobalt 0.001 mg/L EPA 200.8 or 6020A Copper 0.001 mg/L EPA 200.8 or 6020B Hexavalent Chromium 0.000025 mg/L EPA 218.7 Iron 0.01 mg/L EPA 200.7 or 6010C Lead 0.001 mg/L EPA 200.8 or 6020A Lithium 1 mg/L EPA 200.7 or 6010D Manganese 0.005 mg/L EPA 200.7 or 6010C Mercury (low level)0.005 ng/L 1631 ONLY Molybdenum 0.001 mg/L EPA 200.8 or 6020B Nickel 0.001 mg/L EPA 200.8 or 6020B Phosphorus 0.005 mg/L EPA 365.1 Selenium 0.001 mg/L EPA 200.8 or 6020A Strontium 0.005 mg/L EPA 200.7 or 6010C Thallium (low level)0.0002 mg/L EPA 200.8 or 6020A Vanadium (low level)0.0003 mg/L EPA 200.8 or 6020A Zinc 0.005 mg/L EPA 200.7 or 6010C Radium 226 1 pCi/L EPA 903.1 Modified Radium 228 1 pCi/L EPA 904.0/SW846 9320 Modified Uranium (233, 234, 236, 238)Varies by isotope ug/ml SW846 3010A/6020A Alkalinity (as CaCO3)5 mg/L SM 2320B Bicarbonate 5 mg/L SM 2320 Calcium 0.01 mg/L EPA 200.7 Carbonate 5 mg/L SM 2320 Chloride 0.1 mg/L EPA 300.0 or 9056A Magnesium 0.005 mg/L EPA 200.7 Methane 0.01 mg/L RSK 175 Nitrate as Nitrogen 0.01 mg-N/L EPA 353.2 Potassium 0.1 mg/L EPA 200.7 Sodium 0.05 mg/L EPA 200.7 Sulfate 0.1 mg/L EPA 300.0 or 9056A Sulfide 0.1 mg/L SM4500S2-D Total Dissolved Solids 25 mg/L SM 2540C Total Organic Carbon 0.1 mg/L SM 5310C/EPA9060A Total Suspended Solids 2.5 mg/L SM 2450D Prepared by: RBI Checked by: SRW/TCP/VTV Notes: ºC - Degrees Celsius µS/cm = micro-Siemens per centimeter mg/L - Milligrams per liter mg - N/L - Milligrams nitrogen per liter mV - Millivolts NA - Not analyzed NTU - Nephelometric turbidity unit pCi/L - picocuries per liter RL = reporting limit SU - standard unit ug/mL - micrograms per milliliter 2.Analytical methods and reporting limits as presented were applicable at time of CSA field implementation in 2015.Analytical methods and reporting limits are updated periodically and applied as appropriate. INORGANICS FIELD PARAMETERS 1. Select constituents may be analyzed for total and dissolved concentrations. ANIONS/CATIONS RADIONUCLIDES 1 Meeting Minutes Project: Duke Energy Coal Pile Assessments – Allen, Riverbend, and Weatherspoon Subject: Meeting to Discuss NCDEQ Comments to Coal Pile Assessment Work Plans Date: Friday, May 18, 2018 13:00 - 13:56 Location: Conference Call (organized by Duke Energy) Meeting Attendees Duke Energy NCDEQ SynTerra John Toepfer Kent White Judd Mahan Ryan Czop Shuying Wang Chris Suttell Bristol Grohol Jay Zimmerman Courtney Murphy Steve Lanter Julie Robertson Brandy Costner Bryson Sheetz Joanna Harbison Meeting Purpose The purpose of the meeting is to discuss comments recently received from NCDEQ on the Coal Pile Assessment Work Plans for the Allen, Riverbend, and Weatherspoon sites, submitted in January 2018. Meeting Summary Use of Sonic Drilling at 3 sites (Allen, Riverbend, and Weatherspoon) NCDEQ expressed concerns with sonic drilling methods for deep and bedrock wells due to potential elevated turbidity given water amounts typically required for the sonic method. NCDEQ’s position is if well integrity issues are encountered, the expectation is the well will be replaced regardless of drill method chosen. Duke mentioned that they have installed over 1,500 wells at various sites with relatively few pH/turbidity issues. SynTerra mentioned that in prior instances of pH issues at Allen, Duke/SynTerra feel it is likely attributed to a previous consultant using grout as a backfill (rather than bentonite or sand ) when the borehole overshot anticipated well depth. NCDEQ mentioned they prefer to see bentonite-grout used, and recommended consulting closely with drillers to use appropriately-sized filter packs and screens, and additionally, using centralizers to ensure uniform annulus space around well for filter pack. NCDEQ mentioned 2 that when determining most suitable drilling method, be aware that different methods might introduce variables in well construction that are difficult to manage. Submerged Well Screens for Shallow Groundwater Wells (Allen, Riverbend, and Weatherspoon) The pros and cons of submerged shallow screen for this scope were listed by Duke/SynTerra on the respective meeting agenda. NCDEQ will review and provide a response early next week (week of May 21, 2018). NCDEQ mentioned that the industry standard is to bracket the water table for shallow wells, but for the purpose of metals analysis, NCDEQ will internally discuss and consider if screens can be submerged for this scope. Duke mentioned that justification for submerging the screens for similar scopes/purposes had previously been approved for DEP sites. Relocation of W ells to Coal Pile Perimeter vs More Downgradient Location (Riverbend and Weatherspoon) Riverbend – NCDEQ suggested relocating wells closer to the former coal pile footprint so that soil data can be collected within the former coal pile area. Duke/Synterra explained that if wells were added closer to the former coal pile footprint, they would be too close to the wells to the west and north of the coal pile, which are located as close to the water’s edge as possible (limited by steep terrain and wetlands). Duke/SynTerra and NCDEQ agreed to keep the originally proposed well locations and perform additional soil borings at the perimeter of the former coal pile. NCDEQ requested collection of radionuclide samples from material just above the water table; i.e. “the smear zone” at each well cluster and soil boring location. Weatherspoon – Duke/SynTerra and NCDEQ agreed to keep the originally proposed well locations. Site Specific Comments Allen – NCDEQ recommended comparison of data from Coal Pile Assessment with data observed downgradient of ash basin. Duke mentioned this will be a useful data comparison but may not be appropriate to include in a Coal Pile Assessment Report if it is a stand-alone report. NCDEQ expressed that they would prefer not to have separate reports for additional source areas; however, with several Corrective Action Plan (CAP) dates not currently set, it is difficult to determine if additional sources areas can be included in the CAP. It will be determined at a later date in what document/report this information should be included. Riverbend – NCDEQ is concerned with the ~120-foot depth variation between the shallow and deep wells and recommended this difference in depth be reduced. Duke/Synterra explained that the saprolite layer at Riverbend is very thick and the proposed deep well depth intends to capture the transition zone. The well depths may be adjusted depending on field conditions. 3 Weatherspoon – Duke mentioned that a large portion of the coal pile area is inaccessible due to the AST fuel remediation. NCDEQ inquired if Duke could collect samples at existing wells within the AST remediation field. Duke to vet if this will be possible and/or appropriate for the Coal Pile Assessment scope. Action Items • Duke/SynTerra to resubmit revised plans with revised figures. • NCDEQ to respond to Duke early next week (week of May 21, 2018) in regards to submerged screens for shallow wells. • Duke to determine if sampling AST remediation wells is possible and/or appropriate for the Coal Pile Assessment scope. • Duke/SynTerra to schedule a walkdown to stake well locations at Allen, and Duke to invite Brandy and Joanna from NCDEQ MRO to attend. END NOTES