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Home My WebLink AboutCAMA Additional Wells Tech Memo_20190204TECHNICAL MEMORANDUM Date: February 4, 2019 File: 1026.107 To: Kimberlee Witt (Duke Energy) Cc: Craig Eady (SynTerra) From: Kyle Lawing (SynTerra) Subject: Additional Groundwater Monitoring Wells - Roxboro Steam Electric Plant West Ash Basin (WAB) Southern Extension Impoundment (SEI) - Additional Wells Duke Energy Progress, LLC (Duke Energy) owns and operates the Roxboro Steam Electric Plant (Roxboro or Site) in Semora, Person County, North Carolina. Additional groundwater assessment activities proposed for the area south of the West Ash Basin (WAB) Southern Extension Impoundment (SEI) 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 and soil within and around the CCR surface impoundments. A primary source of CCR-related constituents was identified during the Comprehensive Site Assessment (CSA) for CAMA to be related to the two ash basins, the East Ash Basin (EAB) and the West Ash Basin (WAB). In response to the October 2017 CSA Update, the North Carolina Department of Environmental Quality (NCDEQ) requested additional evaluation of groundwater to the south of the WAB SEI to determine the presence, absence, and/or degree of possible impact from historical coal combustion waste management at Roxboro. Site Description Roxboro is a coal-fired steam station owned and operated by Duke Energy that generates electrical power for thousands of customers in North Carolina. The Site is situated on approximately 6,095 acres of company owned property located between McGhees Mill Road to the east, Semora Road (Highway 57) to the south and Hyco Reservoir to the west and north (Figure 1). Roxboro began operations in the 1960s and continued to add capacity through the 1980s. Currently, the Plant operates four coal- fired units. CCR materials, composed primarily of fly ash and bottom ash, were historically managed by depositing ash within two basins (surface impoundments) P:\Duke Energy Progress.1026 \ _ADMINISTRATIVE \ Financial Management \ Project Change Requests (PCRs) \ Roxboro \ Quote 14159 - SEI Data Gap Wells \Tech Memo \Roxboro West Ash Basin SEI Additional Wells Tech Memo.docx West Ash Basin (WAB) Southern Extension Impoundment (SEI) - Additional Wells February 4, 2019 Roxboro Steam Electric Plant Page 2 of 4 located on the Site and referenced using relative location: the EAB and WAB, with construction of each basin beginning in approximately 1966 and 1973, respectively. CCRs were deposited in the basins predominately by hydraulic sluicing operations until the plant was modified for dry fly ash handling operations and the on -site industrial landfill placed in service in the 1980s. Most of the fly ash material produced at the facility is currently collected by dry handling operations and are disposed within the industrial landfill located mostly within the EAB footprint or transported offsite for beneficial reuse. Bottom ash continues to be deposited within the WAB area by hydraulic sluicing methods with expectations for complete dry handling of CCRs in 2019. Groundwater monitoring associated with the Plant's National Pollution Discharge Elimination System (NPDES) permit has been conducted since 2010. WAB Southern Extension Impoundment - Additional Wells Objectives of the WAB SEI additional monitoring well installation includes the following: • Assess soil and groundwater conditions in the vicinity of the two southern "lobes" of the WAB Southern Extension Impoundment, where monitoring wells have not been installed previously • Compare inorganic constituent concentrations in shallow unsaturated soil associated with two monitoring well clusters south of the WAB SEI area to Site background concentrations • Compare inorganic constituent concentrations in groundwater associated with two monitoring well clusters south of the WAB SEI area to Site background concentrations Soil Sampling Soils associated with the monitoring well clusters will be sampled and analyzed for inorganic parameters to determine the presence, absence, and/or degree of possible impact from the CCR materials. Soil samples are planned to be collected from unsaturated, saprolitic soils during the installation of one monitoring well associated with each proposed well cluster. Proposed locations (Figure 2) are approximate and may vary based on field observations and locations of underground utilities, which will be determined prior to initiation of drilling activities. Soil samples will be analyzed for inorganic parameters consistent with assessment of areas used for CCR management (Table 1). Soil samples will be collected from below the near ground surface (two to three feet) and at approximately two to five foot intervals to the top of the groundwater table or bedrock, whichever is encountered first. Soil samples submitted for laboratory analysis will be "grab" samples and will not be P:\Duke Energy Progress.1026 \—ADMINISTRATIVE \ Financial Management \ Project Change Requests (PCRs) \ Roxboro \ Quote 14159 - SEI Data Gap Wells \Tech Memo \Roxboro West Ash Basin SEI Additional Wells Tech Memo.docx West Ash Basin (WAB) Southern Extension Impoundment (SEI) - Additional Wells February 4, 2019 Roxboro Steam Electric Plant Page 3 of 4 composited. Collected soil will be placed directly into new bottleware provided by the NC certified analytical laboratory. Monitoring Well Installation Two monitoring well clusters (three wells per cluster), MW-38 and MW-39, are proposed in the vicinity of the two southern "lobes" of the WAB SEI, as shown on Figure 2. The proposed monitoring wells will be screened in the surficial (S), transition (D), and upper bedrock (BR) flow zones (as saturated conditions are observed) to assess groundwater quality and evaluate horizontal and vertical migration of constituents. Estimated depths from ground surface for each zone are 40 feet below ground surface (bgs) for the surficial well, 80 feet bgs for the transition zone well, and 130 feet bgs for the upper bedrock well as shown on Table 2. The proposed monitoring wells will be installed following appropriate access and permit approvals including NCDEQ Erosion & Sediment Control (E&SC). It is proposed the boreholes will be drilled utilizing one or a combination of the following: hollow -stem augers, air rotary (specifically, pneumatic air hammer), rock coring, and/or rotary sonic drilling techniques. Well installation procedures and well construction materials and lengths will be consistent with ongoing CAMA assessment activities in accordance with the approved Proposed Groundwater Assessment Work Plan (Rev. 1) (SynTerra, 2014) and in accordance with NCAC Title 15A, Subchapter 2C, Section .0100 Well Construction Standards. Shallow wells are proposed to be installed so that the top of the screened interval is positioned approximately five feet below the water table, where practical, to avoid potential biofouling and introduction of artificial geochemical conditions, which are common among monitoring wells with screened intervals that bracket the water table. Groundwater Sampling Following monitoring well installation and development, groundwater samples will be collected from each newly installed well using low flow sampling techniques utilizing either a peristaltic pump or dedicated submersible pump to minimize sampling error, reduce entrainment of suspended sediments and prevent cross contamination of samples. Groundwater samples will be analyzed for field parameters (e.g., pH, specific conductivity, Eh (ORP), DO, and turbidity) and inorganic constituents consistent with ongoing CAMA assessment activities (Table 3). P:\Duke Energy Progress.1026 \—ADMINISTRATIVE \ Financial Management \ Project Change Requests (PCRs) \ Roxboro \ Quote 14159 - SEI Data Gap Wells \Tech Memo \Roxboro West Ash Basin SEI Additional Wells Tech Memo.docx West Ash Basin (WAB) Southern Extension Impoundment (SEI) - Additional Wells February 4, 2019 Roxboro Steam Electric Plant Page 4 of 4 Reporting This information is being gathered to address "data gap" areas as requested by NCDEQ following the review of the Roxboro October 2017 CSA Update, and determined necessary for the forthcoming Corrective Action Plan (CAP) Update document. The results will contribute to the overall understanding of site, with emphasis on the hydrogeologic characteristics, in previously unassessed areas at Roxboro and contribute to the updated Conceptual Site Model. Schedule These assessment activities are to be included in the forthcoming CAP. The additional monitoring well installation activities and sample collection schedule will be dependent on approval of the proposed plan and an executed E&SC permit. Following NCDEQ approval of the workplan, SynTerra and Duke Energy will schedule drilling activities. ATTACHMENTS: Figure 1: Site Location Map Figure 2: West Ash Basin Proposed Locations - Southern Extension Impoundment Table 1: Soil Sample Analytical Methods Table 2: Anticipated Well Construction Details Table 3: Groundwater Analytical Methods P:\Duke Energy Progress.1026 \—ADMINISTRATIVE \ Financial Management \ Project Change Requests (PCRs) \ Roxboro \ Quote 14159 - SEI Data Gap Wells \Tech Memo \Roxboro West Ash Basin SEI Additional Wells Tech Memo.docx West Ash Basin (WAB) Southern Extension Impoundment - Additional Wells February 4, 2019 Roxboro Steam Electric Plant ATTACHMENTS P:\Duke Energy Progress.1026 \—ADMINISTRATIVE \ Financial Management \ Project Change Requests (PCRs) \ Roxboro \ Quote 14159 - SEI Data Gap Wells \Tech Memo \Roxboro West Ash Basin SEI Additional Wells Tech Memo.docx WINN b 1 / RESERVOIR 601E IF, PIP CANAL CANAL •' HEATED WATER DISHARGE POND ft �0111 • pON- 111 NOTES ALL BOUNDARIES ARE APP-. 2016 USGS TOPOGRAPHIC MAP, OLIVE HILL QUADRANGLE, OBTAINED FROM THE USGS STORE AT Wall mv!ffilii hftps://store.usgs.gov/map-locator. -. .FIGURE 1-1 10 SITE LOCATION MAP OWE mill— ROXBORO STEAM ELECTRIC PLANT synTerra DUKE ENERGY PROGRESS, LLC ��.��1 148 RIVER STREET, SUITE 220 29601 DRAWN BY: J. KIRTZ DATE: LEGEND \ PROPOSED WELL CLUSTER (APPROXIMATE) MW 18D WELL IN TRANSITION ZONE MW 18BR WELL IN COMPETENT BEDROCK "scy MW-4B PARCEL LINE DUKE ENERGY (APPROXIMATE) \c M 500 ft COMPLIANCE BOUNDARY APPROXIMATE ASH BASIN WASTE BOUNDARY `l� CW- ® APPROXIMATE FREE PONDED ASH BASIN WATER { FLOW DIRECTION APPROXIMATE POND OR RESERVOIR 0 (NON -JD - JURISDICTIONAL) APPROXIMATE STREAM(NON-JD- JURSIDICTIONAL) SURFACE WATER FLOW DIRECTION ('(' TWT WETLAND APPROVED USACE (USACE #SAW-2014-00189 DATE MAY 16, 2016) O O SOURCE NOTES: u ' NOT ALL UTILITIES ARE IDENTIFIED ON THIS DRAWING. THE UTILITIES SHOWN ON THIS DRAWING ARE VISUAL AIDS TO LOCATE THE STREAMS AND WETLANDS IN THE FIELD. THE HORIZONTAL LOCATION AND THE VERTICAL LOCATIONS HAVE NOT BEEN FIELD i LOCATED ON ANY UTILITIES AND THE SHOWN LOCATIONS ARE APPROXIMATE. i TOPOGRAPHY IS BASED ON LIDAR BARE EARTH DATA OBTAINED FROM THE FRIS NORTH CAROLINA FLOOD RISK INFORMATION SYSTEM ° AT http,.//fris.nc.gov/frls/Download.aspx?FIPS=031&ST=NC&user=General%2OPublic AND A DRAWING TITLED AERIAL TOPOGRAPHIC SURVEY-ROXBORO PLANT BY WSP, JOB NUMBER 1570002.000 AND DRAWING FILE NAME ROXBORO FINAL_06-8-15.DWG 3 FOR STREAM JURISDICTIONAL STATUS REFER TO THE STREAM CLASSIFICATION TABLE CONTAINED IN THE CURRENT USACOE ROXBORO STEAM ELECTRIC PLANT JURISDICTIONAL STREAM AND WETLAND SURVEY. ITHERN IMPOUI` f-IMW-38 BR/ DUKE ENER PROGRE: O� 141 V\IIIIIVv a dO p e 0 250 GRAPHIC 00500 FIGURE 2 IN FEET WEST ASH BASIN PROPOSED LOCATIONS 148 RIVER STREET, SUITE 220 GREENVILLE, SOUTH CAROLINA 29601 SOUTHERN EXTENSION IMPOUNDMENT 999 PHONE 86rracor ADDITIONAL WELLS www.synterra corp.co m .com DRAWNBY:J.CHASTAIN DATE:1/31/2019 ROXBORO STEAM ELECTRIC PLANT 1 PROJECLAYOUT: T CR14159(DATA GAP WELL) SEMORA, NORTH CAROLINA TABLE 1 SOIL SAMPLE ANALYTICAL METHODS ROXBORO STEAM ELETRIC PLANT DUKE ENERGY PROGRESS LLC, ROXBORO, NC 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 7471B 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 6010C Sulfate mg/kg EPA 9056A Thallium mg/kg EPA 6020B Total Organic Carbon mg/kg EPA 9060 Vanadium mg/kg EPA 6020B Zinc I mg/kg IEPA 6010C Prepared by: RBI Checked by: SRW/TCP/VTV Notes: 1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted above. 2. Analytical methods and reporting limits as presented were developed for CSA field implementation in 2015. Analytical methods and reporting limits are updated periodically and applied as appropriate. mg/kg - Milligrams per kilogram S.U. - Standard Unit P:\Duke Energy Progress. 1026�_ADMINISTRATIVE\Financial Management\Project Change Requests (PCRs)\Roxboro\Quote 14159 - SEI Data Gap Wells\Tech Memo\Table 1 Soil Sample Analytical Methods Page 1 of 1 TABLE 2 ANTICIPATED WELL CONSTRUCTION DETAILS WEST ASH BASIN SOUTHERN EXTENSION IMPOUNDMENT ADDITIONAL MONITORING WELLS ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC, SEMORA, NC Proposed Total Proposed Well Well ID Assessment Area Borehole Depth Screened Interval Intended Purpose Well Screen Location Preferred Drilling Method (feet bgs)1, 2 (feet bgs)1,2 MW-38BR Southern 130 120-130 Vertical delineation Upper Bedrock Hollow -Stem Auger/Air Rotary/Coring or Sonic MW-38D Extension 80 70-80 Horizontal delineation Transitional Zone Hollow -Stem Auger/Air Rotary/Coring or Sonic Impoundment 40 30-40 MW-385 Horizontal delineation Surficial/Saprolite Hollow -Stem Auger/Air Rotary/Coring or Sonic MW-39BR Southern 130 120-130 Vertical delineation Upper Bedrock Hollow -Stem Auger/Air Rotary/Coring or Sonic MW-39D Extension 80 70-80 Horizontal delineation Transitional Zone Hollow -Stem Auger/Air Rotary/Coring or Sonic MW-39S Impoundment 40 30-40 Horizontal delineation Surficial/Saprolite Hollow -Stem Auger/Air Rotary/Coring or Sonic Prepared by: KTL Checked by: CDE Notes: 'Proposed well depths based on well construction information from wells MW-18BR and MW-18D. 2Proposed boring depths and screened intervals are estimates; actual screened intervals and total boring depths will be determined based on field observations and approved by a NC Licensed Geologist. PADuke Energy Progress.1026\_ADMINISTRATIVE\Financial Management\Project Change Requests (PCRs)\Roxboro\Quote 14159 - SEI Data Gap Wells\Tech Memo\Table 2 Anticipated Well Construction Details TABLE 3 GROUNDWATER ANALYTICAL METHODS ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS LLC, ROXBORO, NC PARAMETER RL UNITS METHOD FIELD PARAMETERS H 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 m 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 INORGANICS Aluminum 0.005 m L EPA 200.7 or 6010D Antimony 0.001 m L EPA 200.8 or 6020B Arsenic 0.001 m L EPA 200.8 or 6020A Barium 0.005 m L EPA 200.7 or 6010C Beryllium 0.001 m L EPA 200.8 or 6020A Boron 0.05 m L EPA 200.7 or 6010C Cadmium 0.001 m L EPA 200.8 or 6020A Chromium 0.001 m L EPA 200.8 or 6010C Cobalt 0.001 m L EPA 200.8 or 6020A Copper 0.001 m L EPA 200.8 or 6020B Hexavalent Chromium 0.000025 m L EPA 218.7 Iron 0.01 m L EPA 200.7 or 6010C Lead 0.001 m L EPA 200.8 or 6020A Manganese 0.005 m L EPA 200.7 or 6010C Mercury 0.000 m L EPA 245.1 or 7470A Molybdenum 0.001 m L EPA 200.8 or 6020E Nickel 0.001 m L EPA 200.8 or 6020B Selenium 0.001 m L EPA 200.8 or 6020A Strontium 0.005 m L EPA 200.7 or 6010C Thallium low level 0.0002 m L EPA 200.8 or 6020A Vanadium low level 0.0003 m L EPA 200.8 or 6020A Zinc 0.005 m L JEPA 200.7 or 6010C RADIONUCLIDES Radium 226 1 Ci/L EPA 903.1 Modified Radium 228 1 O/L EPA 904.0/SW846 9320 Modified Uranium 223 234 236 238 Varies by Isotope µg/mL SW846 3010A/6020B Total Uranium NA µg/mL Calculated ANIONS/CATIONS Alkalinity as CaCO3 5 m L SM 2320B Bicarbonate 5 m L SM 2320 Calcium 0.01 m L EPA 200.7 Carbonate 5 m L SM 2320 Chloride 0.1 m L EPA 300.0 or 9056A Magnesium 0.005 m L EPA 200.7 Potassium 0.1 m L EPA 200.7 Sodium 0.05 m L EPA 200.7 Sulfate 0.1 m L EPA 300.0 or 9056A Sulfide 0.1 mg/L SM4500S2-D Total Dissolved Solids 25 m L SM 2540C Total Or 29ic Carbon 0.1 m L SM 5310C EPA9060A Total Sus ended Solids 1 2.5 1 m L ISM 2450D Prepared by: RBI Checked by: SRW TCP Notes: 1. Select constituents will be analyzed for total and dissolved concentrations. 2. Analytical methods and reporting limits as presented were developed for CSA field implementation in 2015. Analytical methods and reporting limits are updated periodically and applied as appropriate. OC - Degrees Celsius VS/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 P:\Duke Energy Progress. 1026LADMINISTRATIVE\Financial Management\Project Change Requests (PCRs)\Roxboro\Quote 14159 - SEI Data Gap Wells\Tech Memo\Table 3 Groundwater Analytical Methods Page 1 of 1