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HomeMy WebLinkAboutNC0001422_FPA Assessment Tech Memo Final_20180629TECHNICAL MEMORANDUM P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment- Work Plan\FPA\FPA Assessment Tech Memo Final.docx Date: June 2018 File: 1026.108.49 To: John Toepfer (Duke Energy) Cc: Kathy Webb (SynTerra) From: Perry Waldrep Subject: Soil and Groundwater Assessment – Former Process Area – L.V. Sutton Energy Complex Duke Energy Progress, LLC (Duke Energy) owns and operates the L.V. Sutton Energy Complex (Site) located on approximately 3,300 acres near Wilmington, NC. The Site started operations in 1954 with three coal-fired boilers that primarily used bituminous coal as fuel to produce steam to generate electricity. Ash generated from coal combustion was originally stored on-site in the 'former ash disposal area (FADA)', also known as the ‘lay of land area’, then in the 1971 ash basin (old ash basin), and finally the 1984 ash basin (new ash basin). These ash storage areas are referred to as the ash management area. Additionally, there is an area known as the Former Process Area (FPA) located adjacent to the southeast corner of the 1971 basin which contains CCR and CCR-like solids. The Site ceased burning coal in November 2013 and switched to natural gas for electricity generation, thus the facility no longer generates coal ash. Groundwater and soil assessment activities for the FPA 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. In 2015, the United States Environmental Protection Agency (USEPA) signed a CCR rule requiring all CCR disposal facilities to establish a groundwater detection monitoring plan. CCR groundwater monitoring wells were installed in 2016 near the southwestern edge of the former process area. Historical data are also available from two previously existing, nearby downgradient monitoring wells. Boron, an inorganic constituent that is commonly used as an indicator of CCR impacts to groundwater, has been detected above background concentrations in these wells near the FPA. Additional assessment of the FPA also identified vanadium as a potential constituent of concern. Further assessment is warranted so that the FPA can be incorporated into a Corrective Action Plan (CAP) for the Site. Soil and Groundwater Assessment – Former Process Area June 2018 L.V. Sutton Energy Complex Page 2 of 4 P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment- Work Plan\FPA\FPA Assessment Tech Memo Final.docx Site Description The FPA is a small settling basin which was used when the plant was co-firing fuel oil. The FPA measures approximately 250 feet by 150 feet with concrete-lined side walls and a concrete divider, which was subsequently filled with solids including CCR and solids which have chemical signatures similar to CCR. The approximate FPA boundary is shown on Figure 1. Former Process Area Assessment Objectives Objectives of the FPA assessment include the following: Characterize inorganic constituents associated with FPA soils Characterize inorganic constituent concentrations in shallow groundwater underlying the FPA and along the FPA perimeter Compare inorganic constituent concentrations in FPA groundwater to downgradient well concentrations as well as Site background concentrations. Historical Investigations There have been two separate assessments of the FPA, both performed by Geosyntec. An investigation in 2014 included soil and groundwater sampling from seven locations surrounding the perimeter of the FPA (Geosyntec, 2015). A subsequent investigation in 2015 took soil samples from six locations inside the footprint of the FPA (Geosyntec, 2016). The assessment outlined in this work plan will incorporate data reported in both of these reports. Soil Assessment Eight locations will be sampled and analyzed for inorganic parameters to define the horizontal delineation of soils in the vicinity of the FPA. Analytical results on samples collected from borings performed during the Geosyntec assessment, both within and along the perimeter of the FPA, indicate CCR impact. Soils will be collected at proposed monitoring well locations (FPA-1 through FPA-4) as part of well installation activities. Unsaturated soils will be collected at four locations (FPA-4 through FPA-8) around the perimeter of the FPA. One proposed sample location (FPA-1) is within the footprint of the FPA (Figure 1). Soil samples will be collected at approximately 2-foot intervals to the top of the groundwater table. Within the FPA, samples will be taken two feet above the basin floor, two feet below the basin floor, and two feet above the water table. The unsaturated soil samples will be analyzed for inorganic parameters as listed on Table 1. Additional soil samples will be collected below the water table within the new wells screened intervals; these samples will be analyzed for hydrous ferric oxides (HFO) and Soil and Groundwater Assessment – Former Process Area June 2018 L.V. Sutton Energy Complex Page 3 of 4 P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment- Work Plan\FPA\FPA Assessment Tech Memo Final.docx hydrous aluminum oxides (HAO) to support the geochemical modeling effort. Please note, SPLP analyses were conducted during the previous Geosyntec assessments and is therefore not included in this workplan. Additionally, uranium and radium have been assessed at locations upgradient (TW-46, TW-132, TW-136) and downgradient of the FPA (MW-19, MW-21C, MW-22B/C, MS-28B/C) with no detections above standards, therefore these constituents are not included in this workplan. Groundwater Assessment Eight former process area (FPA) groundwater monitoring wells are proposed to characterize FPA groundwater. One upper surficial (“B”), and one lower surficial (“C”),groundwater monitoring well (FPA-1B/C) will be installed within the FPA footprint. FPA-1B/C will be located on the west side of the concrete divider. Six wells (FPA-2B/C, FPA-3B/C & FPA-4B/C) will be installed downgradient of the FPA. Proposed approximate FPA well installation locations are shown on Figure 1 and proposed well details are provided as Table 2. Well installation procedures will be consistent with ongoing CAMA assessment activities in accordance with the Revised Groundwater Assessment Work Plan (SynTerra, December 2014). As such, shallow wells are proposed to be installed so that the top of the screened interval is positioned approximately 5 ft. below the water table, where practical, to avoid potential issues such as biofouling and introduction of artificial redox conditions which are common among monitoring wells with screened intervals that bracket the water table. This approach for well screen intervals was outlined in a May 18, 2018 email (and subsequent teleconference) from Duke Energy to NCDEQ. NCDEQ responded via email on May 23, 2018 supporting the proposed technical approach and rationale concerning these procedures. 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 consistent with ongoing CAMA assessment activities (Table 3.) Former Process Area Assessment Report A former process area 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) Evaluation and interpretation of analytical results. Existing Site data will be used in this evaluation 4) Conclusions and Recommendations Soil and Groundwater Assessment – Former Process Area June 2018 L.V. Sutton Energy Complex Page 4 of 4 P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment- Work Plan\FPA\FPA Assessment Tech Memo Final.docx In addition to the FPA Report, the data collected will be included in the Corrective Action Plan Update. ATTACHMENTS Table 1: Soil Analytical Methods Table 2: Proposed Former Process Area Assessment Soil Samples and Monitoring Wells Table 3: Groundwater Analytical Methods Figure 1: Proposed Monitoring Well and Soil Boring Locations Soil and Groundwater Assessment – Former Process Area June 2018 L.V. Sutton Energy Complex P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment- Work Plan\FPA\FPA Assessment Tech Memo Final.docx ATTACHMENTS TABLE 1 SOIL ANALYTICAL METHODS L.V. SUTTON ENERGY COMPLEX DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment-Work Plan\FPA\ Tables.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 Chromium (Hexavalent)mg/kg EPA 7199 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 Synthetic Precipitation Leaching Procedue (SPLP)µg/L EPA 1312 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: PBW 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. TABLE 2 PROPOSED FORMER PROCESS AREA ASSESSMENT SOIL SAMPLES AND MONITORING WELLS L.V. SUTTON ENERGY COMPLEX DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment-Work Plan\FPA\ Tables.xlsx Page 1 of 1 Monitoring Well ID Estimated Well Depth (feet bgs) Soil Sample ID (Estimated Depth Interval in feet bgs)* Comments ----FPA-1SB (X-X)Unsaturated soil sample 2 feet above bottom of basin ----FPA-1SB (X-X)Unsaturated soil sample 2 feet below the bottom of basin ----FPA-1SB (X-X)Unsaturated soil sample 2 feet above water table FPA-1B 25 FPA-1SB (23-24)**Soil sample from upper surficial well screened interval FPA-1C 50 FPA-1SB (47-48)**Soil sample from lower surfiical well screened interval ----FPA-2SB (1-2)Near-surface unsaturated soil sample (water table ~~6 feet bgs) ----FPA-2SB (2-4)Unsaturated soil sample ----FPA-2SB (4-6)Unsaturated soil sample 2 feet above water table FPA-2B 25 FPA-2SB (23-24)**Soil sample from upper surficial well screened interval FPA-2C 50 FPA-2SB (47-48)**Soil sample from lower surfiical well screened interval ----FPA-3SB (1-2)Near-surface unsaturated soil sample (water table ~~6 feet bgs) ----FPA-3SB (2-4)Unsaturated soil sample ----FPA-3SB (4-6)Unsaturated soil sample 2 feet above water table FPA-3B 25 FPA-3SB (23-24)**Soil sample from upper surfiical well screened interval FPA-3C 50 FPA-3SB (47-48)**Soil sample from lower surficial well screened interval ----FPA-4SB (1-2)Near-surface unsaturated soil sample (water table ~~6 feet bgs) ----FPA-4SB (2-4)Unsaturated soil sample ----FPA-4SB (4-6)Unsaturated soil sample 2 feet above water table FPA-4B 25 FPA-4SB (23-24)**Soil sample from upper surfiical well screened interval FPA-4C 50 FPA-4SB (47-48)**Soil sample from lower surficial well screened interval ----FPA-5SB (4-6)Unsaturated soil sample ----FPA-6SB (1-2)Near-surface unsaturated soil sample (water table ~~6 feet bgs) ----FPA-6SB (2-4)Unsaturated soil sample ----FPA-6SB (4-6)Unsaturated soil sample ----FPA-7SB (1-2)Near-surface unsaturated soil sample (water table ~~6 feet bgs) ----FPA-7SB (2-4)Unsaturated soil sample ----FPA-7SB (4-6)Unsaturated soil sample ----FPA-8SB (1-2)Near-surface unsaturated soil sample (water table ~~6 feet bgs) ----FPA-8SB (2-4)Unsaturated soil sample ----FPA-8SB (4-6)Unsaturated soil sample Notes: bgs = below ground surface ~ = Approximately * Unsaturated thickness based on original site grade and does not include recently placed fill ** HFO Analyses Only 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 CCR-102 cluster and available Geosyntec boring logs. SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet TABLE 3 GROUNDWATER ANALYTICAL METHODS L.V. SUTTON ENERGY COMPLEX DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC P:\Duke Energy Progress.1026\108. Sutton Ash Basin GW Assessment Plan\49.Former Process Area Assessment-Work Plan\FPA\ Tables.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/6020B Total Uranium NA µg/mL Calculated 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 &> ?&> &> ? &> ? ? &< &< &< &< &> &> &> &> &> &> &> &> &> &> &> &> &> &< HA-3 HA-6 FPA-4B/C 198 3 EXTENSION FPA-7SB FPA-1B/C FPA-8SB FPA-5SB FPA-3B/C FPA-6SB FPA-2B/C HA-1HA-2 HA-4 HA-5 MW-17 MW-18 V-DPT-1 V-DPT-2 V-DPT-3 V-DPT-4 V-DPT-5 V-DPT-6 V-DPT-7 CCR-102C ³ DRAWN BY: A . ROBINSONCHECK BY: B. WYLIEPROJECT M ANAGER: P. WALDREP DATE: 3/26/2018 148 RIVER STREE T, SUITE 220GREENVILLE, SO UTH CAROLINA 29601PHONE 864-421-9999www.synterracorp.com P:\Duke Energy Progress.1026\00 GIS BASE DATA\Sutton\Map_Docs\CSA_Supplement_2\Proposed Monitoring W ell and Soil Boring.mxd FIG URE 1PROPOSED M ONITORING WELL AND SOILBORING LOCATIONSL.V. SUTTON ENERGY COM PLEXDUKE ENERGY PROGRESS, LLCWILMINGTON, NORTH CAROLINA 30 0 30 6015 IN FEET LEGEND &>HAND AUGERED SAMPLING LOCATION &>DPT SAMPLING LOCATION &<MONITORING WELL (ABANDONED) ?PROPOSED MONITORING W ELL &>PROPOSED SOIL BORING WASTE BOUNDARY FORMER PROCESS AREA BOUNDARY FADA BOUNDARY COM PLIANCE BOUNDARY NOTES: HAND AUGERED LOCATIONS ARE APPROXIMATE. SITE AERIAL ORTHOPHOTOGRAPHY OBTAINED FROM W SP, DATED 2014. DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CAROLINA STATE PLANECOORDINATE SYSTEM FIPS 3200 (NAD83/2011).