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HomeMy WebLinkAboutCCB0070_DukeBelewsCreek_GWAssessmentMonitoringPlan_DIN27003_20161107Belews Creek Steam Station 3195 Pine Hall Road Belews Creek, NC 27009 336-445-0610 336-669-2994 www.duke-energy.com Page 1 of 2 November 7, 2016 North Carolina Department of Environmental Quality Division of Waste Management Solid Waste Section 1646 Mail Service Center Raleigh, North Carolina 28778 Attn: Ms. Elizabeth Werner Re: Proposed Groundwater Assessment and Monitoring Plan Belews Creek Steam Station BCSS .1700 Structural Fill Permit No.: CCB0070 Belews Creek Steam Station Stokes County Belews Creek, North Carolina 27009 Dear Ms. Werner, Attached you will find the Proposed Groundwater Assessment and Monitoring Plan for the Belews Creek BCSS .1700 Structural Fill. This plan is being submitted to the Division for approval. Duke Energy is committed to excellent environmental stewardship and cooperation with the Division regarding the operation, maintenance, safety, and integrity of all of its facilities. We look forward to continuing to work with you regarding environmental concerns. If there are any questions regarding this request, please contact me at (336) 445-0610. Respectfully submitted, Melonie Martin Environmental Services Attachments: Proposed Groundwater Assessment and Monitoring Plan, Belews Creek Steam Station BCSS .1700 Structural Fill, Permit No. CCB0070 www.duke-energy.com Page 2 of 2 cc (via e-mail): Ed Mussler, NCDEQ Shawn McKee, NCDEQ Evan Andrews, Duke Energy Will Harrison, Duke Energy Kimberlee Witt, Duke Energy Ed Sullivan, Duke Energy Proposed Groundwater Assessment and Monitoring Plan Belews Creek Steam Station BCSS .1700 Structural Fill Stokes County, North Carolina November 2016 Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill i Contents Section 1 – Introduction ............................................................................................................. 3 Section 2 – Proposed Groundwater Assessment and Monitoring Plan ....................................... 6 2.1 Groundwater Assessment ............................................................................................ 6 2.2 Groundwater Monitoring............................................................................................... 6 2.3 Monitoring Well Installation .......................................................................................... 6 2.3.1 Well Installation Methods and Construction Requirements.................................... 7 2.3.2 Well Development ................................................................................................. 8 2.3.3 Well Survey .......................................................................................................... 9 2.3.4 Investigative Derived Waste .................................................................................10 2.3.5 Documentation .....................................................................................................10 2.4 Sample Collection and Analysis ..................................................................................10 2.4.1 Soil Sampling .......................................................................................................10 2.4.2 Groundwater Sampling ........................................................................................12 2.4.3 Surface Water Sampling ......................................................................................14 2.4.4 AOW Sampling ....................................................................................................14 Section 3 – Proposed Quality Assurance Plan ..........................................................................15 3.1 Field Documentation ...................................................................................................15 3.1.1 Field Logbooks ....................................................................................................15 3.1.2 Field Data Records ..............................................................................................15 3.2 Laboratory Documentation ..........................................................................................16 3.3 Quality Control ............................................................................................................17 3.3.1 Field Duplicates ...................................................................................................17 3.3.2 Field Blanks .........................................................................................................17 3.3.3 Data Validation ....................................................................................................17 Section 4 – Reporting................................................................................................................18 4.1 Assessment Report .....................................................................................................18 4.2 Monitoring Reports ......................................................................................................18 Section 5 – Proposed Schedule for Assessment and Monitoring ..............................................19 5.1 Assessment Schedule ................................................................................................19 5.2 Monitoring Schedule ...................................................................................................19 Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill ii FIGURES Figure 1 – Site Location Map Figure 2 – Site Layout Map Figure 3 – Proposed Well and Sample Locations Figure 4 – Monitoring Well Construction Details TABLES Table 1 – Proposed Monitoring Well Installation Plan Table 2 – Soil and Ash Parameters and Constituent Analytical Methods Table 3 – Groundwater Parameters and Constituent Analytical Methods Table 4 – Proposed Schedule for Assessment of BCSS .1700 Structural Fill Table 5 – Proposed Schedule for Monitoring of BCSS .1700 Structural Fill APPENDICES Appendix A – Low Flow Sampling Plan, Duke Energy Facilities, Ash Basin Groundwater Assessment Program, North Carolina, June 10, 2015 Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 3 Section 1 – Introduction Duke Energy Carolinas, LLC (Duke Energy) owns and operates the Belews Creek Steam Station (BCSS), located on Belews Lake in Stokes County, North Carolina (Figure 1). BCSS began operation in 1974 and operates two coal-fired units. Coal combustion residuals (CCR) and other liquid discharges from BCSS’s coal combustion process have been disposed in the ash basin since its construction. In 1983, BCSS converted to dry handling of fly ash with disposal in on-site landfills; bottom ash is sluiced to the ash basin and fly ash is sluiced to the ash basin on start-up and in emergency situations. Discharge from the ash basin is permitted by the North Carolina Department of Environmental Quality (NCDEQ) Division of Water Resources (DWR) under the National Pollutant Discharge Elimination System (NPDES) Permit NC0024406. Between February 2004 and July 2009, Duke Energy constructed a structural fill, using fly ash generated from BCSS under the structural fill rules found in 15A NCAC 13B .1700. The BCSS .1700 Structural Fill number CCB0070 (structural fill) is located south of the BCSS ash basin and Pine Hall Road (Figure 2). The structural fill is currently used as an equipment/material staging area and for overflow parking. The fill was constructed with the required thickness of soil as a final cover in accordance with the .1700 rules. An engineered cover system, utilizing a geomembrane, a geonet drainage system, and vegetated soil cover system, was constructed over the structural fill in 2012. In accordance with requirements in the Coal Ash Management Act of 2014 (CAMA), Duke Energy conducted a comprehensive site assessment (CSA) at the BCSS ash basin in 2015. Per the approved CSA work plan, ash used in the structural fill was not considered part of the source area and was not evaluated during the CSA. As part of the CSA, surface water samples were collected from an area of wetness (AOW) location (S-9) south of the ash basin and west of the structural fill (Figure 2). Analytical results from S-9 exhibited exceedances of standards specified in 15A NCAC 02L .0202 Groundwater Quality Standard (2L Standard) for boron, cobalt, sulfate, and total dissolved solids (TDS) and an exceedance of the interim maximum allowable concentration (IMAC) for cobalt. Installation and sampling of additional groundwater monitoring wells in the area south of Pine Hall Road and adjacent to the structural fill was recommended in the CSA Report. To refine understanding of the source of the exceedances near S-9, monitoring wells GWA-23S and GWA-23D were installed and sampled as part of the CAMA Round 5 sampling event (April 2016). Groundwater monitoring well pair GWA-23S/D was installed in April 2016, approximately 450 feet west of the structural fill and approximately 300 feet north of S-9 (Figure 2). Monitoring well GWA-23S was installed with a 15-foot screened interval set to bracket the water table and monitoring well GWA-23D was installed with a 5-foot screened interval in the transition zone, below auger refusal. The location for well pair GWA-23S/D is approximately 1300 feet south of the ash basin, approximately 860 feet south of the Chemical Treatment Pond, and approximately 450 feet west of the structural fill. The installed depths of the well screens are provided below. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 4 GWA-23S GWA-23D Top of Casing (feet) 811.79 811.57 Groundwater Elevation (feet) 786.57 786.64 Screen Length (BGS - feet) 15 5 Top of Screen (BGS - feet) 24.40 56.61 Bottom of Screen (feet) 39.40 61.61 Top of Screen (elevation – feet) 787.39 754.96 Bottom of Screen (elevation – feet) 772.39 749.96 The ash basin full pond elevation is 750 feet. The surveyed water elevation in the Chemical Treatment Pond in April 2014 was 772.0 feet. A pond depth survey performed by HDR in June 2014 measured an approximate maximum depth of 15 feet below the pond water surface. If the water surface was at or near the April 2014 elevation of 772 feet, the corresponding elevation would be 757 feet. The water elevation in this pond has been lowered and the surveyed elevation in April 2016 was approximately 760.4 feet. Exceedances of boron, cobalt, iron, manganese, sulfate, TDS, vanadium, and pH were found in groundwater samples collected from GWA-23S/D after installation in April 2016. Concentrations of the constituents in GWA-23S and GWA-23D are similar, indicating that the concentrations are from the same source. The bottom of screen elevation in GWA-23S is 772.39 feet, approximately 12 feet above the pond elevation in the Chemical Treatment Pond (760.4 feet) and approximately 22.4 feet above the ash basin full pond elevation (750 feet). This comparison of the elevation of the screen in GWA-23S and the ash basin full pond elevation indicate that the source of the exceedances in GWA-23S is not the ash basin. Although the bottom of screen elevation for GWA-23D (754.96 to 749.96 feet) is lower than the Chemical Treatment Pond area historical elevation (772 feet), based on the similar nature of the exceedances, it is likely that the same source is the cause of the exceedances in both GWA- 23S and GWA-23D. The approximate elevation for AOW S-9 is 792 feet, which is greater than water elevations in the ash pond and the Chemical Treatment Pond. Additional evidence is noted in the comparison of the analytical results for boron, sulfate, and TDS between monitoring wells GWA-9S/D and in GWA-9BR (well screened in bedrock), located in the earthen dike for the Chemical Treatment Pond area, and the results for these constituents in GWA-23S/D. As an example, boron is listed by the US EPA as a detection monitoring constituent due to its association with impacts from CCR and its mobility in groundwater. Boron concentrations in GWA-9S/D were less than the laboratory reporting limit of 50 µg/L during sampling Rounds 1, 2, 5, and 6, and was reported in monitoring well GWA-9BR at 211 µg/L during the sampling conducted in June 2016. Boron concentrations in GWA-23D were 3,540 µg/l and 3,080 µg/L in sampling performed in April 2016 and May 2016, respectively. Groundwater flow maps for the shallow (saprolite) and deep (transition zone) flow layers based on a gauging event performed on May 9, 2016 show a distinct groundwater drainage divide along Pine Hall Road between the ash basin and GWA-23S/D and S-9, further indicating that the exceedances are not related to the ash basin (Figures 3-1 and 3-2 in CSA Supplement 2 Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 5 dated August 11, 2016). The data indicates the presence of a drainage divide along Pine Hall Road, and is consistent with the slope-aquifer system as clearly identified in the shallow and deep flow layers. The exceedances in GWA 23S/D are consistent with constituents associated with coal ash and a potential source could be the nearby structural fill. As the structural fill was constructed under the North Carolina Department of Environmental Quality (NCDEQ) Division of Waste Management (DWM) structural fill rules found in 15A NCAC 13B .1700, Duke Energy notified DWM of these exceedances and the assessment outlined below will be reported to the NCDEQ DWM. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 6 Section 2 – Proposed Groundwater Assessment 2.1 Groundwater Assessment – Phase 1 Duke Energy proposes to perform a Phase 1 groundwater assessment to evaluate exceedances of 2L Standards in the vicinity of wells GWA-23S/D and AOW sample location S-9 located adjacent to the structural fill. The purpose of the Phase 1 assessment is to investigate if the structural fill is the source of groundwater exceedances at these locations. Duke Energy will install a total of one shallow (SFMW-1S) and one deep (SFMW-1D) monitoring well to evaluate groundwater flow direction and quality near the structural fill as shown on Figure 3 (locations shown as proposed monitoring well locations – Phase 1). Duke Energy will also collect samples from the four proposed surface water locations (SFSW-1 through SFSW-4) and AOW S-9 shown on Figure 3. Duke Energy proposes to conduct field sampling and laboratory analyses as described in the following sections. After review of the results from these activities, Duke Energy will evaluate the need for additional investigation, sampling, and analyses to support the assessment as well as any modifications to the following Phase 2 groundwater assessment plan. 2.2 Groundwater Assessment – Phase 2 If the results of the Phase 1 groundwater assessment confirm the structural fill as the source of groundwater exceedances in GWA-23S/D and AOW S-9, Duke Energy proposes to perform a Phase 2 groundwater assessment. Duke Energy will install a total of four shallow (SFMW-2S, SFMW-3S, SFMW-4S, and SFMW- 5S) and four deep (SFMW-2D, SFMW-3D, SFMW-4D, and SFMW-5D) monitoring wells to monitor groundwater flow direction and quality near the structural fill as shown on Figure 3 (locations shown as proposed monitoring well locations – Phase 2). Duke Energy will also collect samples from monitoring wells SFMW-1S and SFMW-1D, and AOW S-9 (Figure 3) as part of the Phase 2 groundwater assessment. 2.3 Monitoring Well Installation Soil samples will be collected for laboratory analyses during installation of the monitoring wells to evaluate concentrations of constituents in the soil. Shallow well depths are estimated to be approximately 50 feet bgs. The deep wells are estimated to be installed to be approximately 100 feet bgs. Well screens in the shallow wells will be installed to bracket the water table at the time of installation. The well screens in the deep monitoring wells will be installed in partially weathered rock (if present), below auger refusal. Proposed well locations and rationale for installation are provided in the table below. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 7 Table 1 – Proposed Monitoring Well Installation Plan PROPOSED WELL ID PROPOSED LOCATION PURPOSE FOR INSTALLATION Assessment Phase 1 SFMW-1S West side of structural fill outside of the waste boundary Groundwater elevation and quality west of the structural fill between the fill and the surface water drainage to the west; collect soil samples SFMW-1D West side of structural fill outside of the waste boundary Groundwater elevation and quality west of the structural fill between the fill and the surface water drainage to the west; collect soil samples Assessment Phase 2 SFMW-2S North of the structural fill on south side of Pine Hall Road Groundwater elevation and quality upgradient of the structural fill; collect soil samples SFMW-2D North of the structural fill on south side of Pine Hall Road Groundwater elevation and quality between the ash basin and GWA-23S/D; collect soil samples SFMW-3S South/southwest side of structural fill outside of the waste boundary Groundwater elevation and quality south/southwest (downgradient) of the structural fill; collect soil samples SFMW-3D South/southwest side of structural fill outside of the waste boundary Groundwater elevation and quality south/southwest (downgradient) of the structural fill; collect soil samples SFMW-4S South/southeast side of structural fill outside of the waste boundary Groundwater elevation and quality south/southeast (downgradient) of the structural fill; collect soil samples SFMW-4D South/southeast side of structural fill outside of the waste boundary Groundwater elevation and quality south/southeast (downgradient) of the structural fill; collect soil samples SFMW-5S East/southeast side of structural fill outside of the waste boundary Groundwater elevation and quality east/southeast (downgradient) of the structural fill; collect soil samples SFMW-5D East/southeast side of structural fill outside of the waste boundary Groundwater elevation and quality east/southeast (downgradient) of the structural fill; collect soil samples 2.3.1 Well Installation Methods and Construction Requirements Monitoring wells will be installed using drilling equipment appropriate for terrain at the drill site. The drilling equipment will be clean and free from dirt, debris, and contaminants. Drilling will be conducted in accordance with appropriate standard-of-care for the specified drilling technology. Drill crews will be trained and experienced using the specific drilling techniques and equipment. Monitoring wells will be constructed by a North Carolina-licensed driller in accordance with the NCDEQ Division of Water Quality standards as specified in 15A NCAC 02C and under the direction of a North Carolina-licensed geologist. Bentonite-based or synthetic-based drilling fluids are not anticipated for use during installation of the monitoring wells. Only water from the actual boring or an approved source will be used for drilling. All storage containers used for transportation or storage of the water will be new or properly decontaminated prior to use at the site. Decontamination of downhole drilling equipment (such as augers, drill rods, cutting heads, etc.) will be completed between well locations. After completion of a well, a water pressure cleaner Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 8 will be used to decontaminate downhole tooling prior to reuse. If needed, brushes and water from an approved source will be used to remove excess soil, mud, or other material from drilling equipment. The decontamination water will be pumped into drums or placed directly onto the ground surface. 2.3.1.1 MONITORING WELL CONSTRUCTION Shallow (single-cased) monitoring wells (S wells) will be installed to bracket the water table encountered in unconsolidated material (i.e., regolith or overburden) at the time of drilling and a 10-foot to 15-foot screen will be installed. Each well will be constructed with a 2-inch-inner- diameter, Schedule 40 flush-joint-threaded PVC pipe fitted with a 20/40 (sand) pre-packed PVC 0.010-slot screen and a 2-inch-inner-diameter Schedule 40 PVC casing to the ground surface. An additional filter pack (#2 sand) will be placed to at least 1 foot above the screen with a minimum of 1-foot to 2-foot bentonite seal placed above the filter pack. The remaining annular space will be grouted with a Portland cement-bentonite slurry to the ground surface using positive displacement (i.e., tremie grout method). The monitoring well will be fitted with a lockable well cap. For shallow monitoring well construction details see Figure 4. Deep (double-cased) monitoring wells (D wells) will be installed in partially weathered rock (PWR) to weathered rock for monitoring in the transition zone. The wells will be constructed using a 6-inch-inner-diameter PVC outer casing seated approximately 1 foot into PWR, if present. The annulus between the borehole and outer casing will be grouted using the tremie grout method and will be allowed to cure for approximately 24 hours. The borings will be advanced to approximately 15 feet below the bottom of the outer casing. The deep monitoring wells will be constructed with a 2-inch-inner-diameter, schedule 40 flush-joint-threaded PVC pipe fitted with a 5-foot long 20/40 (sand) pre-packed PVC 0.010-slot screen and a 2-inch-inner- diameter schedule 40 PVC casing to the ground surface. An additional filter pack (#2 sand) will be placed to at least 1 foot above the screen with a minimum of 1 to 2 foot bentonite seal placed above the filter pack. The remaining annular space will grouted with a Portland cement- bentonite slurry to the ground surface using positive displacement (i.e., tremie grout method). The monitoring wells will be fitted with a lockable well cap. For typical deep monitoring well construction details see Figure 4. 2.3.1.2 MONITORING WELL SURFACE COMPLETION Each well will be finished at the ground surface with a 2-foot by 2-foot concrete well pad and a 4-inch or 8-inch steel or aluminum above-grade lockable protective cover. All wells will be locked with a keyed padlock. Bollards will be installed as needed to protect monitoring wells from potential damage from vehicles and/or heavy equipment. 2.3.2 Well Development Each monitoring well will be developed prior to commencing groundwater sampling activities. Monitoring well development will be performed in general accordance with the following procedures. Deviations from these procedures will be verified by the Project Manager prior to implementation. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 9 1. Monitoring well development will not be performed until 24 hours have passed after well completion to allow for grout/cement curing. 2. The duration of development, initial water level, well depth, development method (i.e., bailing, surging, pumping), and field parameter measurements (listed in item #4 below) will be documented on a Well Development Record. 3. Monitoring wells will be developed using pumping and surging techniques. The wells will be pumped using a centrifuge or submersible pump (Wahl, Monsoon, or equivalent) to remove suspended particles and induce flow into the well to prevent clogging of the filter pack. Wells that cannot be developed utilizing a pump due to insufficient volume may use a bailer to evacuate the well. If it is determined by the developers that there is a significant sediment slug at the bottom of the well, it can be removed using a foot valve pump or bailer in lieu of the centrifugal or submersible pump. Once removed, well development will continue with the centrifugal or submersible pump. 4. Field parameter measurements of dissolved oxygen (DO), oxidation reduction potential (ORP), pH, temperature, specific conductivity, and turbidity will be recorded for every 5 gallons of discharge. A 5-gallon bucket can be used for purge water volume measurements. For wells with slow recovery, field parameters will be checked every 2 gallons of discharge. 5. Pumping should begin at the top of the well screen with low pumping rates and incrementally work down the screen. The well will be surged periodically by raising and lowering the pump within the water column three to five times in succession, being careful not to touch the bottom of the well with the pump. If turbidity values remain over 10 Nephelometric Turbidity Units (NTU), the well will be allowed to equilibrate (90 percent or greater of the original static water level) and the process repeated. 6. Development will continue for a minimum of 1 hour or three well volumes (whichever duration is longer) until turbidity is less than 10 NTU and until monitoring parameters of pH, temperature, conductivity, and turbidity are generally stabilized. 7. If development has continued longer than 3 hours and turbidity values remain in excess of 10 NTU, the well should be allowed to equilibrate for 24 hours or 90 percent of the original static water level, and the development process will be repeated until turbidity is less than 10 NTU. If turbidity readings do not decrease after multiple developments, the development team will consult the Project Manager to discuss other options to resolve current conditions, including reinstallation. 8. Following development, sounding of the bottom of the well with a water level meter should indicate a “hard” (sediment-free) bottom. 2.3.3 Well Survey Newly installed monitoring wells will be surveyed for horizontal and vertical locations by a North Carolina-licensed surveyor. The measuring points will include: 1) the top of the 2-inch PVC well casing, and 2) ground surface at each monitoring well in the groundwater monitoring network. The location and position accuracy will be approximately 1.0-foot for horizontal control, 0.1-foot for ground surface elevation, and 0.01-foot for well top-of-casing (TOC) elevation. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 10 The locations and elevations of the surface water sample locations will be surveyed when the well location surveys are performed. 2.3.4 Investigative Derived Waste IDW such as nitrile gloves, paper towels, and other miscellaneous waste generated during well installation will be bagged, placed in a commercial dumpster, and managed as municipal solid waste. Soil cuttings generated during drilling will be spread near monitoring well locations so that it is not a safety concern and seed/straw will be applied to aid in restoration. Water generated during decontamination of equipment, monitoring well development, and sampling will be discharged to the ground surface in the vicinity of the decontamination pad or monitoring well location. Alternatively, cuttings and water may be stored in drums and properly disposed either on site or off site. 2.3.5 Documentation Documentation of field activities will be completed using a combination of log books and field forms. Log books are completed to provide a general record of activities and events that occur during daily tasks (e.g., detailed descriptions of subsurface media encountered and observations made during boring installation). During well installation and development of the monitoring wells, the following field forms will be used for documentation: • Boring logs will be utilized to document lithology and details of boring advancement. • Monitoring well construction logs will be utilized to record final well construction details. • Monitoring well development record forms will be utilized to document well development activities for each newly installed monitoring well (see Section 2.1.2). Duke Energy will submit a well construction record (NCDEQ Form GW-1) to NCDEQ for newly installed groundwater monitoring wells. 2.4 Sample Collection and Analysis For this groundwater assessment plan, sampling will consist of collection and analysis of soil, groundwater, surface water, and AOW samples. For the groundwater monitoring plan, sampling will consist of soil, groundwater, and AOW samples. Sample analyses will be performed by a North Carolina-certified analytical laboratory. 2.4.1 Soil Sampling 2.4.1.1 SAMPLING PROCEDURES Split-spoon (SPT) and disturbed sampling is proposed during installation of wells using a split- spoon sampler driven 18 inches into the ground with an automatic 140-pound hammer. SPT will be conducted at 5-foot intervals (3.5 feet between samples) for the soil samples (e.g., 3.5 feet to 5 feet, 8.5 feet to 10 feet, 13.5 feet to 15 feet, 18.5 feet to 20 feet). After collection, the sampler will be opened and recovered material will be described in the field in accordance with the Unified Soil Classification System (USCS). Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 11 To evaluate concentrations of constituents in the soil, samples will be collected approximately halfway from the ground surface to the water table and approximately 5 feet above the water table from each of the shallow monitoring well borings for laboratory analysis. 2.4.1.2 CONSTITUENT ANALYSES Duke Energy proposes to analyze soil samples for parameters and constituents consistent with those analyzed during the CAMA CSA at BCSS in 2015 (Table 2). The laboratory analytical methods employed will be consistent with the methods used during the CSA. The soil analytical results will be compared to the North Carolina Preliminary Soil Remediation Goals (PSRGs) for Industrial Health and Protection of Groundwater Standards. Table 2 – Soil Parameters and Constituent Analytical Methods INORGANIC COMPOUNDS UNITS METHOD Aluminum mg/kg EPA 6010 Antimony mg/kg EPA 6020 Arsenic mg/kg EPA 6020 Barium mg/kg EPA 6010 Beryllium mg/kg EPA 6010 Boron mg/kg EPA 6010 Cadmium mg/kg EPA 6020 Chloride mg/kg EPA 9056 Chromium (Total) mg/kg EPA 6010 Hexavalent Chromium (CrVI) (low level) mg/kg EPA 3060 Cobalt mg/kg EPA 6020 Copper mg/kg EPA 6010 Iron mg/kg EPA 6010 Lead mg/kg EPA 6020 Manganese mg/kg EPA 6010 Mercury mg/kg EPA 7471 Molybdenum mg/kg EPA 6020 Nickel mg/kg EPA 6010 pH SU EPA 9045 Selenium mg/kg EPA 6020 Strontium mg/kg EPA 6020 Thallium (low level) mg/kg EPA 6020 Vanadium mg/kg EPA 6020 Zinc mg/kg EPA 6010 Calcium mg/kg EPA 6010 Magnesium mg/kg EPA 6010 Nitrate mg/kg EPA 9056 Nitrogen mg/kg EPA 353.2 Potassium mg/kg EPA 6010 Sodium mg/kg EPA 6020 Sulfate mg/kg EPA 9056 Total Organic Carbon mg/kg EPA 9060 Modified Notes: 1. mg/kg – milligrams per kilogram 2. SU – standard units Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 12 2.4.2 Groundwater Sampling 2.4.2.1 GROUNDWATER LEVEL MEASUREMENTS Prior to groundwater purging and sampling activities, a depth-to-water (DTW) measurement will be recorded in each well during a comprehensive gauging event (not to exceed a 24- to 48-hour period). Groundwater levels will be measured using an electronic water level indicator that will be decontaminated between each well prior to measurement activities. The DTW measurements will be referenced to the well TOC mark established by a site survey and will provide data used to generate a potentiometric surface map for the area. In addition to the newly installed monitoring wells as part of the groundwater assessment, DTW measurements will also be recorded in monitoring wells AB-9S, AB-9D, AB-9BR, GWA-7S, GWA-7D, GWA-8S, GWA-8D, MW-3, MW-7, GWA-23S, GWA-23D, GWA-12S, GWA-12D, and GWA-12BR. Groundwater level measurements will only be collected from the proposed assessment and monitoring wells as part of the groundwater monitoring plan. 2.4.2.2 GROUNDWATER PURGING AND SAMPLING PROCEDURES Subsequent to well installation and development, groundwater samples will be collected from each monitoring well using low flow sampling techniques as outlined in the Low Flow Sampling Plan, Duke Energy Facilities, Ash Basin Groundwater Assessment Program, North Carolina, June 10, 2015 (Low Flow Sampling Plan) (Appendix A) to collect samples that are representative of ambient groundwater conditions in the aquifer.. In addition to the wells proposed for installation during the assessment, groundwater samples will also be collected from monitoring wells AB-9S, AB-9D, AB-9BR, GWA-7S, GWA-7D, GWA- 8S, GWA-8D, MW-3, MW-7, GWA-23S, GWA-23D, GWA-12S, GWA-12D, and GWA-12BR. Groundwater samples will only be collected from the proposed assessment and monitoring wells as part of the groundwater monitoring plan. Groundwater purging and sampling will be conducted using new or dedicated tubing for each well. Bladder, peristaltic, and/or submersible pumps will be utilized to achieve minimum drawdown. Purge water will be pumped from the monitoring well into a flow-through cell, which will allow for monitoring of field parameters using an YSI Professional Plus multi-parameter water quality meter or similar instrument. Turbidity will be measured using a separate turbidity meter. Field parameters to be measured during purging and sampling and will include pH, temperature, specific conductivity, DO, ORP, and turbidity, as listed below in Table 3. Filtered and unfiltered samples using a 0.45-micron filter will be collected. 2.4.2.3 CONSTITUENT ANALYSES A laboratory certified in North Carolina will analyze groundwater samples for the constituents and analytical methods listed in Table 3. The constituents will be analyzed for total recoverable and dissolved fraction concentrations. The record of groundwater analyses will include the methods used (by number), the extraction date (if applicable), and the date of analysis. Data obtained from samples that are not analyzed within the recommended holding times will be considered suspect and flagged accordingly. Any deviation from approved methods will be adequately tested to ensure that the quality of the results meets the performance specifications (e.g., detection limit, sensitivity, precision, accuracy) of the reference method. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 13 Table 3 – Groundwater Parameters and Constituent Analytical Methods PARAMETER RL UNITS METHOD FIELD PARAMETERS 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 INORGANICS Aluminum 5 µg/L EPA 200.7 or 200.8 Antimony 1 µg/L EPA 200.7 or 200.8 Arsenic 1 µg/L EPA 200.7 or 200.8 Barium 5 µg/L EPA 200.7 or 200.8 Beryllium 1 µg/L EPA 200.7 or 200.8 Boron 50 µg/L EPA 200.7 or 200.8 Cadmium 1 µg/L EPA 200.7 or 200.8 Chromium 1 µg/L EPA 200.7 or 200.8 Hexavalent Chromium 0.07 µg/L EPA 200.7 or 200.8 Cobalt 1 µg/L EPA 200.7 or 200.8 Copper 0.005 mg/L EPA 200.7 or 200.8 Iron 10 µg/L EPA 200.7 or 200.8 Lead 1 µg/L EPA 200.7 or 200.8 Manganese 5 µg/L EPA 200.7 or 200.8 Mercury 0.2 µg/L EPA 245.1 Molybdenum 0.5 µg/L EPA 200.7 or 200.8 Nickel 1 µg/L EPA 200.7 or 200.8 Selenium 1 µg/L EPA 200.7 or 200.8 Strontium 5 µg/L EPA 200.7 or 200.8 Thallium (low level) 0.2 µg/L EPA 200.7 or 200.8 Vanadium (low level) 0.3 µg/L EPA 200.7 or 200.8 Zinc 5 µg/L EPA 200.7 or 200.8 ANIONS/CATIONS Alkalinity (as CaCO3) 20 mg/L SM 2320B Bicarbonate 20 mg/L SM 2320B Calcium 0.01 mg/L EPA 200.7 or 200.8 Carbonate 20 mg/L SM 2320B Chloride 0.1 mg/L EPA 300.0 Magnesium 0.001 mg/L EPA 200.7 or 200.8 Methane 0.1 mg/L RSK 175 Nitrate as Nitrogen 0.02 mg-N/L EPA 353.2 Potassium 0.1 mg/L EPA 200.7 or 200.8 Sodium 0.05 mg/L EPA 200.7 or 200.8 Sulfate 0.1 mg/L EPA 300.0 Sulfide (as H2S) 0.05 mg/L SM4500S2-D Total Dissolved Solids 25 mg/L SM 2540C Total Organic Carbon 0.1 mg/L SM 5310B Total Suspended Solids 2 mg/L SM 2540D Notes: 1. Units: SU – standard units; µS/cm – microsiemens per centimeter; ºC – degrees Celsius; mg/L – milligrams per liter; mV – millivolts; NTU – Nephelometric Turbidity Unit; µg/L – microgram per liter; mg-N/L – milligrams nitrogen per liter. 2. RL is the laboratory analytical method reporting limit. 3. NA indicates not applicable. 4. Sulfide (as H2S) will be analyzed for groundwater samples only. 5. All EPA methods and RLs are at or below the respective criteria (2L Standards, IMACs, DHHS HSL) for constituents with criteria. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 14 Sample preservation and handling will be conducted in accordance with the procedures specified in Sections 3.5.1 and 3.5.2 of the Low Flow Sampling Plan (Appendix A). Decontamination will be conducted in accordance with the procedures specified in Appendix A (Decontamination of Equipment Standard Operating Procedure) of the Low Flow Sampling Plan (Appendix A). 2.4.3 Surface Water Sampling As part of the groundwater assessment Duke Energy will collect four surface water samples (SFSW-1 through SFSW-4) from the two surface water drainage features located upstream of AOW S-9. Samples will be obtained using a telescoping cup sampler or collected directly into laboratory prepared sampling containers and will be analyzed for the same list of parameters and constituents, using the same laboratory analytical methods, as the groundwater samples (listed in Table 3). Filtered and unfiltered samples using a 0.45-micron filter will be collected. These surface water locations will not be sampled as part of the structural fill monitoring plan. 2.4.4 AOW Sampling AOW S-9 will be sampled during the assessment and analyzed for the same list of parameters and constituents using the same laboratory methods as the groundwater samples (listed in Table 3). Filtered and unfiltered samples using a 0.45-micron filter will be collected. AOW S-9 will also be sampled as part of the structural fill monitoring plan. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 15 Section 3 – Proposed Quality Assurance Plan The Quality Assurance Plan (QAP) has been prepared to specify quality assurance/quality control (QA/QC) procedures for collection, analysis, and evaluation of data that will be legally and scientifically defensible. The QAP provides general information and references standard operating procedures applicable to the analytical sampling program. This information includes definitions and generic goals for data quality and required types and quantities of QA/QC samples. The procedures address field documentation; sample handling, custody and shipping; instrument calibration and maintenance; auditing; data reduction, validation, and reporting; corrective action requirements; and QC reporting specific to the analysis performed by the NCDEQ-approved laboratory. 3.1 Field Documentation Documentation of field activities will be completed using a combination of field log books, field data records (FDRs), sample tracking systems, and sample custody records. The log books and FDRs will be completed to provide a general record of activities and events that occur during each field task. FDRs and/or sample custody records are used to provide a complete record of data collected during sampling. 3.1.1 Field Logbooks Field logbooks will provide a daily hand-written account of field activities. The logbooks utilized will be bound hardcover books. Entries will be made in indelible ink and corrections will be made with a single line with the author initials and date. Each page of the logbook will include the job number, date, and initials of the person completing the log. Partially completed pages will have a line drawn through the unused portion at the end of each day with the author’s initials. The following general information will be entered into the field logbooks: • The date and time of each entry. The daily log will begin with a safety brief. • A summary of important tasks or subtasks completed during the day. • A description of field test completed in association with the daily task. • A description of samples collected including documentation of any quality control samples that were prepared (i.e., rinse blanks, duplicates, matrix spike, split samples, etc.). • Documentation of equipment maintenance and calibration activities. • Documentation of equipment decontamination activities. • Descriptions of deviations from the work plan. 3.1.2 Field Data Records FDRs will contain sample collection and/or exploration details. A FDR will be completed each time a field sample is collected. The purpose of the FDR is to document exploration and sample collection methods, materials, dates and times, and sample locations and identifiers. Field measurements and observations associated with a given exploration or sample collection task will be recorded on the FDRs. FDRs will be maintained throughout the field program in files that become a permanent record of field program activities. A listing of FDRs is presented below. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 16 Each FDR listed will not be required for each step-specific activity that may or may not be required over the entire project. Examples of FDRs include: • Groundwater Potentiometric Level Measurement Log • Well Sampling/Low Flow Sampling Log • Well Installation and Boring Log • Well Development Record • Field Instrument Calibration Record 3.2 Laboratory Documentation A program of sample tracking and custody will be followed during sample handling activities in both field and laboratory operations. This program will be designed to ensure that each sample is accounted for at all times. The appropriate sampling and laboratory personnel will complete sample FDRs, chain-of-custody records, and laboratory receipt sheets. Additional information documented in the chain-of-custody may be required such as shipping information for samples sent by courier. Each sample container will typically have a label affixed to it and will be prepared prior to sampling to include the following information: • Sample location using a unique sample identification (i.e., SFMW-1S) • Date and time collected • Sampler identification • Analyses requested and applicable preservative The chain-of-custody (COC) will be initiated at the time of sample collection to provide record of the following: • Sample location (ID), number of containers corresponding to each sample, and sample handling procedures • Applicable preservatives and analyses requested • Date and time of sample collection • Name of sampler(s) and person(s) shipping the samples (if applicable) • Date and time samples were relinquished (e.g., picked up by lab courier) • If samples are shipped, a custody seal will be affixed to outside of each sample cooler • Name(s) of those responsible for receiving the samples at the laboratory COCs will be prepared by the field sampler who will be responsible for the care and integrity of samples until they are properly relinquished to the laboratory or shipped. Sample containers will be packed in coolers to reduce movement during transport to the laboratory. Styrofoam and bubble-pack may be used as packing materials, if needed. Ice will be placed in the coolers. Paperwork (COC forms) will be placed in a separate, re-sealable, water- tight, plastic bag within the cooler. A temperature blank provided by the laboratory will be placed in each cooler, if required by the laboratory to verify the cooler was maintained at 4º Celcius (C) [+/- 2ºC] during sample transport. Custody seals will be placed across the lid and cooler-body interface prior to shipment to or pick up by the laboratory. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 17 3.3 Quality Control Field QC samples are not included specifically as laboratory QC samples but are analyzed when submitted to provide quality control data relative to the field sampling and sample management procedures. Data for field QC samples will be reported with associated samples. Field QA/QC samples will be analyzed for the same constituents as soil or groundwater samples (Tables 2 and 3) unless otherwise noted. 3.3.1 Field Duplicates Field duplicates are two samples of the same matrix which are collected, to the extent possible, from the same location at the same time using the same techniques. Field duplicates provide information on the precision of the sampling and analysis process. Field duplicates will be collected at a frequency of one duplicate for every 20 samples collected (per media). If the total number of samples collected per media is less than 20, one field duplicate will be collected per day, per media of sampling. 3.3.2 Field Blanks Field blanks are prepared in the field to evaluate the potential for contamination of a sample by site contaminants from a source not associated with the sample collected (examples include dust or organic vapors). Analyte-free water provided by the laboratory will be brought to the field by the sampling crew and transferred to the proper sample container for shipment along with the other samples collected. One field blank sample will be collected per sampling day. 3.3.3 Data Validation Data validation describes an analyte-specific and sample-specific process of evaluating that a data set meets method, procedure, and contract requirements. Data review and validation will be performed in accordance with the United States Environmental Protection Agency (USEPA) Contract Laboratory Program (CLP) National Functional Guidelines for Superfund Organic Methods Data Review (USEPA 2014a) and the USEPA CLP National Functional Guidelines for Inorganic Data Review (USEPA 2014b). Analytical data will be reviewed and validated at a rate of 100 percent. Analytical results and qualifiers will be assessed using professional judgment to determine the final quality and usability of the data. Examples of data validation qualifiers include: U The analyte was analyzed for, but was not detected to the method detection limit, and was not quantifiable to the reporting limit. J The result is an estimated quantity. The associated numerical value is the approximate concentration of the analyte in the sample. J+ The result is an estimated quantity, but the result may be biased high J- The result is an estimated quantity, but the result may be biased low. UJ The analyte was not detected; however, the result is estimated due to discrepancies in meeting certain analyte-specific quality control criteria. R The data are unusable. The sample results are rejected due to serious deficiencies in meeting QC criteria. The analyte may or may not be present in the sample. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 18 Section 4 – Reporting 4.1 Phase 1 Assessment Report The results of the work performed under the Phase 1 groundwater assessment plan will be reported to the NCDEQ DWM as a Phase 1 groundwater assessment report (Assessment Report – Phase 1). The Assessment Report – Phase 1 will present the findings of the soil sampling and analyses, well installation, and groundwater, surface water, and AOW sampling activities. Supporting figures (e.g., chembox, potentiometric surface, and isoconcentration figures) and tables (e.g., well construction, groundwater elevation, and analytical tables) will be included in the Assessment Report – Phase 1 to summarize and interpret the results of the work associated with the structural fill. As discussed in Section 2, Duke Energy proposes to perform the activities described and to collect and analyze samples of soil, groundwater, surface water, and AOWs as needed. After the initial review of the results from these activities, Duke Energy will evaluate if additional investigation, sampling, and analyses are needed to confirm the structural fill as the source of exceedances. These additional assessment activities could include completion of additional borings to collect soil samples or installation of additional groundwater monitoring wells. Duke Energy proposes to communicate the results of the initial review with the NCDEQ DWM prior to conducting additional assessment activities. 4.2 Phase 2 Assessment Report The results of the work performed under the Phase 2 groundwater assessment plan will be reported to the NCDEQ DWM as a Phase 2 groundwater assessment report (Assessment Report – Phase 2). The Assessment Report – Phase 2 will present the findings of the soil sampling and analyses, well installation, and groundwater, and AOW sampling activities. Supporting figures (e.g., chembox, potentiometric surface, and isoconcentration figures) and tables (e.g., well construction, groundwater elevation, and analytical tables) will be included in the Assessment Report – Phase 2 to summarize and interpret the results of the work associated with the structural fill. As discussed in Section 2, Duke Energy proposes to perform the activities described and to collect and analyze samples of soil, groundwater, surface water, and AOWs as needed. After the initial review of the results from these Phase 2 activities, Duke Energy will evaluate if additional investigation, sampling, and analyses are needed. These additional assessment activities could include completion of additional borings to collect soil samples or installation of additional groundwater monitoring wells. Duke Energy Carolinas, LLC | Belews Creek Steam Station Proposed Groundwater Assessment and Monitoring Plan: BCSS .1700 Structural Fill 19 Section 5 – Proposed Schedule for Assessment 5.1 Assessment Schedule – Phase 1 The schedule for completion of the Phase 1 groundwater assessment scope of work is contingent on NCDEQ DWM approval of the proposed groundwater assessment plan. HDR proposes the following schedule for the Phase 1 assessment tasks (Table 4) relative to receipt of authorization and Notice to Proceed (NTP) by Duke Energy procurement and subsequent to NCDEQ approval of the proposed groundwater assessment plan. Table 4 – Proposed Schedule for Phase 1 Assessment of BCSS .1700 Structural Fill TASK PROPOSED TIMELINE – AFTER APPROVAL BY NCDEQ AND RECEIPT OF AUTHORIZATION AND NOTICE TO PROCEED Erosion and Sediment Control Plan 2 weeks Erosion and Sediment Control Plan Approval 4 weeks after submittal of erosion and sediment control plan Monitoring Well Installation 4 weeks after approval of erosion and sediment control plan Sample Collection and Analysis 2 weeks after completion of well installation Data Validation 2 weeks after receipt of laboratory analytical reports Submittal of Phase 1 Groundwater Assessment Report 8 weeks after completion of data validation 5.2 Assessment Schedule – Phase 2 The schedule for completion of the Phase 2 groundwater monitoring scope of work is contingent on NCDEQ DWM approval of the proposed groundwater monitoring plan and the results of the Phase 1 groundwater assessment report confirming the structural fill as the source of exceedances. HDR proposes the following schedule for the Phase 2 assessment tasks (Table 5) relative to receipt of authorization and Notice to Proceed (NTP) by Duke Energy procurement and subsequent to NCDEQ approval of the proposed groundwater monitoring plan. Table 5 – Proposed Schedule for Phase 2 Assessment of BCSS .1700 Structural Fill TASK PROPOSED TIMELINE – AFTER APPROVAL OF PHASE 1 ASSESSMENT REPORT BY NCDEQ AND RECEIPT OF AUTHORIZATION AND NOTICE TO PROCEED Erosion and Sediment Control Plan 2 weeks Erosion and Sediment Control Plan Approval 4 weeks after submittal of erosion and sediment control plan Monitoring Well Installation 6 weeks after approval of erosion and sediment control plan Sample Collection and Analysis 2 weeks after completion of well installation Data Validation 2 weeks after receipt of laboratory analytical reports Submittal of Phase 2 Groundwater Assessment Report 8 weeks after completion of data validation Duke Energy Carolinas, LLC | Belews Creek Steam Station Groundwater Assessment Plan: BCSS .1700 Structural Fill Figures   ASH LANDFILLPERMIT NO.8503 FGDLANDFILLPERMIT NO.8505  CRAIG ROADLANDFILLPERMIT NO.8504     1000 2000  0 1000      DATE FIGURE SITE LOCATION MAPBCSS .1700 STRUCTURAL FILL ASSESSMENTDUKE ENERGY CAROLINAS, LLC STOKES COUNTY, NORTH CAROLINA NOVEMBER 2016 1 SITE LOCATION MAPBCSS .1700 STRUCTURAL FILL ASSESSMENT BELEWS CREEK STEAM STATION STOKES COUNTY, NORTH CAROLINA OCTOBER 2016 1 A S H B A S I N EL E V A T I O N 7 5 0 F T ( A P P R O X I M A T E ) D U K E P O W E R S T E A M P L A N T R O A D M I D D L E T O N L O O P PINE H A L L R D MARTIN LUTHERKING JR RD B E L E W S C R E E K S T E A M S T A T I O N B E L E W S L A K E E L E V A T I O N 7 2 5 F T ( A P P R O X I M A T E ) PINE HALL RD PINE HALL ROADASH LANDFILLPERMIT NO. 85-03 S T R U C T U R A L F I L L SW-DR-U/SD-DR-U SW-DR-D / S D - D R - D UNNAMED STREAMUNNAMED STREAMMIDDLETON LOOP UNNAMED STREAM (LITTLE BELEWS CREEK)OLD PLANTATION ROADGEORGIA ROAD DUKE ENERGYPROPERTY D U K E E N E R G Y P R O P E R T Y D U K E E N E R G Y P R O P E R T Y DUKE ENERGYPROPERTY D U K E P O W E R S T E A M P L A N T R O A D S W - B L - U / S D - B L - U ( W E S T O F C R A I G R O A D A S H L A N D F I L L ) S W - B L - D / S D - B L - D 3 3 31 34 4 0 4 1 4 6 4 2 4 3 4 4 3 6 89 1 1025 321112132614227328291516453017181920216 3 7 22 3 8 4 5 23247 3 9 474948 M W - 2 0 1 D G W A - 2 3 S G W A - 2 3 D G W A - 2 2 S / D M W - 2 0 1 B R GWA-21S/DGWA-25BR GWA-16BRGWA-26S/D/BR C H E M I C A L P O N D GWA-27S/D/BR GWA-20SA/D/BRGWA-9BR L E G E N D : D U K E E N E R G Y P R O P E R T Y B O U N D A R Y A S H B A S I N W A S T E B O U N D A R Y L A N D F I L L / S T R U C T U R A L F I L L B O U N D A R Y A S H B A S I N C O M P L I A N C E B O U N D A R Y P I N E H A L L R O A D A S H L A N D F I L L C O M P L I A N C E B O U N D A R Y A S H B A S I N C O M P L I A N C E B O U N D A R Y C O I N C I D E N T W I T H D U K E P R O P E R T Y B O U N D A R Y S T R E A M T O P O G R A P H I C C O N T O U R W E T L A N D A R E A N C D E Q S A M P L E L O C A T I O N S A S H B A S I N V O L U N T A R Y G R O U N D W A T E R M O N I T O R I N G W E L L A S H B A S I N C O M P L I A N C E G R O U N D W A T E R M O N I T O R I N G W E L L C S A G R O U N D W A T E R M O N I T O R I N G W E L L P O S T - C S A A D D I T I O N A L A S S E S S M E N T G R O U N D W A T E R M O N I T O R I N G W E L L C S A S U R F A C E W A T E R A N D / O R S E D I M E N T S A M P L E L O C A T I O N C S A A R E A O F W E T N E S S S A M P L E L O C A T I O N P U B L I C W A T E R S U P P L Y W E L L F I E L D I D E N T I F I E D P R I V A T E W A T E R S U P P L Y W E L L R E C O R D E D P R I V A T E W A T E R S U P P L Y W E L L A S S U M E D P R I V A T E W A T E R S U P P L Y W E L L R E P O R T E D P R I V A T E W A T E R S U P P L Y W E L L                           D A T E F I G U R E S I T E L A Y O U T B C S S . 1 7 0 0 S T R U C T U R A L F I L L A S S E S S M E N T D U K E E N E R G Y C A R O L I N A S , L L C B E L E W S C R E E K S T E A M S T A T I O N NOTES:1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.2. WASTE BOUNDARY IS APPROXIMATE.3. EXISTING MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY AND WSP.4. EXSITING SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.5. EXSITING DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.6. EXISTING BEDROCK MONITORING WELLS (BR) ARE SCREENED ACROSS WATER BEARING FRACTURES IN COMPETENT BEDROCK.7. TOPOGRAPHY DATA FOR ONSITE WAS OBTAINED FROM WSP (DATED 2015).8. TOPOGRAPHY DATA FOR OFFSITE WAS OBTAINED FROM NCDOT GEOGRPAHIC INFORMATION SYSTEM (GIS) WEB SITE (DATED 2007).9. AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.10. HYDROGRAPHY WAS OBTAINED FROM THE PROVISIONAL JURISDICTIONAL WATERS MAP, PROVIDED BY AMEC FOSTER WHEELER, DATED MAY 29, 2015.* VOLUNTARY MONITORING WELLS MW-101S, MW-101D, MW-103S AND MW-103D WERE ABANDONED IN 201611. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L .0107 (a).12. THE COMPLIANCE BOUNDARY SHOWN ON THIS FIGURE IS FROM THE 2015 COMPREHENSIVE SITE ASSESSMENT REPORT SUBMITTED TO DEQ ON SEPTEMBE R 9 , 2 0 1 5 , A N D I S N O T REPRESENTATIVE OF RECENT PROPERTY LINE REVISIONS ALONG MIDDLETON LOOP ROAD.13. PARCEL DATA FOR THE 2.23-ACRE PROPERTY NORTHWEST OF THE ASH BASIN WAS OBTAINED FROM LDSI, INC. (SURVEY DATED SEPTEMBER 29, 2016).14. PROPERTY RESEARCH CONDUCTED BY DUKE ENERGY IN AUGUST 2016 INDICATES THAT DUKE ENERGY'S PROPERTY ALONG MIDDLETON LOOP ROAD EXTEN D S T O T H E 2 . 2 3 - A C R E P A R C E L A N D INCLUDES THE ROADWAY WHERE DUKE ENERGY PROPERTY EXISTS ON BOTH SIDES OF MIDDLETON LOOP ROAD (i.e., THE PROPERTY EXTENDS TO APPROXI M A T E L Y T H E C E N T E R O F T H E R O A D W A Y ) . D U K E P O W E R S T E A M P L A N T R O A D B E L E W S C R E E K S T E A M S T A T I O N E L E V A T I O N 7 2 5 F T PINE HALL RD PINE HALL ROADASH LANDFILLPERMIT NO. 85-03 S T R U C T U R A L F I L L DUKE ENERGYPROPERTY D U K E P O W E R S T E A M P L A N T R O A D GWA-23SGWA-23D C H E M I C A L P O N D GWA-9BR L E G E N D : D U K E E N E R G Y P R O P E R T Y B O U N D A R Y A S H B A S I N W A S T E B O U N D A R Y L A N D F I L L / S T R U C T U R A L F I L L B O U N D A R Y A S H B A S I N C O M P L I A N C E B O U N D A R Y P I N E H A L L R O A D A S H L A N D F I L L C O M P L I A N C E B O U N D A R Y A S H B A S I N C O M P L I A N C E B O U N D A R Y C O I N C I D E N T W I T H D U K E P R O P E R T Y B O U N D A R Y S T R E A M F I E L D O B S E R V E D S U R F A C E W A T E R D R A I N A G E F E A T U R E ( A P P R O X I M A T E ) T O P O G R A P H I C C O N T O U R W E T L A N D A R E A N C D E Q S A M P L E L O C A T I O N S A S H B A S I N V O L U N T A R Y G R O U N D W A T E R M O N I T O R I N G W E L L A S H B A S I N C O M P L I A N C E G R O U N D W A T E R M O N I T O R I N G W E L L C S A G R O U N D W A T E R M O N I T O R I N G W E L L P O S T - C S A A D D I T I O N A L A S S E S S M E N T G R O U N D W A T E R M O N I T O R I N G W E L L C S A S U R F A C E W A T E R A N D / O R S E D I M E N T S A M P L E L O C A T I O N C S A A R E A O F W E T N E S S S A M P L E L O C A T I O N P R O P O S E D B C S S . 1 7 0 0 S T R U C T U R A L F I L L A S S E S S M E N T M O N I T O R I N G W E L L L O C A T I O N - P H A S E 1 P R O P O S E D B C S S . 1 7 0 0 S T R U C T U R A L F I L L A S S E S S M E N T S U R F A C E W A T E R S A M P L E L O C A T I O N - P H A S E 1 P R O P O S E D B C S S . 1 7 0 0 S T R U C T U R A L F I L L A S S E S S M E N T M O N I T O R I N G W E L L L O C A T I O N - P H A S E 2                           D A T E F I G U R E P R O P O S E D W E L L A N D S A M P L E L O C A T I O N S B C S S . 1 7 0 0 S T R U C T U R A L F I L L A S S E S S M E N T D U K E E N E R G Y C A R O L I N A S , L L C B E L E W S C R E E K S T E A M S T A T I O N NOTES:1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.2. WASTE BOUNDARY IS APPROXIMATE.3. EXISTING MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY AND WSP.4. EXSITING SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.5. EXSITING DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.6. EXISTING BEDROCK MONITORING WELLS (BR) ARE SCREENED ACROSS WATER BEARING FRACTURES IN COMPETENT BEDROCK.7. TOPOGRAPHY DATA FOR ONSITE WAS OBTAINED FROM WSP (DATED 2015).8. TOPOGRAPHY DATA FOR OFFSITE WAS OBTAINED FROM NCDOT GEOGRPAHIC INFORMATION SYSTEM (GIS) WEB SITE (DATED 2007).9. AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.10. HYDROGRAPHY WAS OBTAINED FROM THE PROVISIONAL JURISDICTIONAL WATERS MAP, PROVIDED BY AMEC FOSTER WHEELER, DATED MAY 29, 2015.* VOLUNTARY MONITORING WELLS MW-101S, MW-101D, MW-103S AND MW-103D WERE ABANDONED IN 201611. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L .0107 (a).12. THE COMPLIANCE BOUNDARY SHOWN ON THIS FIGURE IS FROM THE 2015 COMPREHENSIVE SITE ASSESSMENT REPORT SUBMITTED TO DEQ ON SEPTEMBE R 9 , 2 0 1 5 , A N D I S N O T REPRESENTATIVE OF RECENT PROPERTY LINE REVISIONS ALONG MIDDLETON LOOP ROAD.13. PROPERTY RESEARCH CONDUCTED BY DUKE ENERGY IN AUGUST 2016 INDICATES THAT DUKE ENERGY'S PROPERTY ALONG MIDDLETON LOOP ROAD EXTEN D S T O T H E 2 . 2 3 - A C R E P A R C E L A N D INCLUDES THE ROADWAY WHERE DUKE ENERGY PROPERTY EXISTS ON BOTH SIDES OF MIDDLETON LOOP ROAD (i.e., THE PROPERTY EXTENDS TO APPROXI M A T E L Y T H E C E N T E R O F T H E R O A D W A Y ) . D A T E F I G U R E NOTES:1. MONITORING WELLS WILL BE CONSTRUCTED IN ACCORDANCE WITH 15A NCAC 02C .0108 STANDA R D S O F C O N S T R U C T I O N : W E L L S O T H E R THAN WATER SUPPLY.2. WELL TAG IDs TO BE ATTACHED TO WELL PROTECTIVE COVER WITH MECHANICAL RIVETS.3. PROTECTIVE BOLLARDS (CONE-TAPERED, FILLED WITH CONCRETE, AND PAINTED YELLOW) ARE TO B E I N S T A L L E D A S N E C E S S A R Y . 4. SLOPE 2' X 2' CONCRETE PAD SURFACE UPWARD TO PROTECTIVE COVER TO PREVENT PONDING W A T E R . 5. WELL ID TO BE ETCHED IN 2' X 2' CONCRETE PAD.6. ALL CONSTRUCTION MEASUREMENTS ARE APPROXIMATE. P R O P O S E D W E L L C O N S T R U C T I O N D E T A I L S B C S S . 1 7 0 0 S T R U C T U R A L F I L L A S S E S S M E N T D U K E E N E R G Y C A R O L I N A S , L L C B E L E W S C R E E K S T E A M S T A T I O N S T O K E S C O U N T Y , N O R T H C A R O L I N A Duke Energy Carolinas, LLC | Belews Creek Steam Station Groundwater Assessment Plan: BCSS .1700 Structural Fill Appendix A Low Flow Sampling Plan, Duke Energy Facilities, Ash Basin Groundwater Assessment Program, North Carolina, June 10, 2015 Low Flow Sampling Plan Duke Energy Facilities Ash Basin Groundwater Assessment Program North Carolina June 10, 2015 Duke Energy | Low Flow Groundwater Sampling PlanTable of Contents TABLE OF CONTENTS Low Flow Sampling Plan ....................................................................................................... 1 1.0 PURPOSE ............................................................................................................................... 1 2.0 GENERAL CONSIDERATIONS ............................................................................................. 1 3.0 PROCEDURES ....................................................................................................................... 2 3.1 Pre-Job Preparation ............................................................................................................. 2 3.2 Water-Level Measurements ................................................................................................. 3 3.3 Well Purging ........................................................................................................................ 4 3.3.1 Low-Flow Well Purging ............................................................................................ 4 3.3.2 Volume-Averaging Well Purging .............................................................................. 8 3.4 Sampling ....................................................................................................................... 10 3.4.1 Low-Flow Sampling ............................................................................................... 10 3.4.2 Sampling after Volume-Averaging Purge ............................................................... 11 3.5 Sample Handling, Packing, and Shipping ..................................................................... 11 3.5.1 Handling ................................................................................................................ 11 3.5.2 Sample Labels ....................................................................................................... 11 3.5.3 Chain-of-Custody Record ...................................................................................... 12 3.6 Field Quality Control Samples ....................................................................................... 12 3.7 Field Logbook Documentation....................................................................................... 13 3.8 Decontamination and Waste Management ................................................................... 14 4.0 REFERENCES ..................................................................................................................... 14 APPENDIX ADecontamination of Equipment SOP ................................................................... 15 1.0 Purpose & Application ...................................................................................................... 16 2.0 Equipment & Materials .......................................................................................................... 16 3.0 Procedure ............................................................................................................................. 16 3.1 Decontamination of Non-Disposable Sampling Equipment .......................................... 16 3.2 Decontamination of Field Instrumentation .................................................................... 16 3.3 Decontamination of Groundwater Sampling Equipment ............................................... 17 3.4 Materials from Decontamination Activities .................................................................... 17 APPENDIX BSampling Equipment Check List – Table 1.......................................................... 18 APPENDIX CField Logbook/Data Sheets ................................................................................. 20 Duke Energy | Low Flow Groundwater Sampling Plar1.0 PURPOSE 1 1.0 PURPOSE The purpose of this low flow sampling plan is to establish a standard operating procedure (SOP) to describe collection procedures for groundwater samples from monitoring wells using low-flow purging and sampling techniques or by the volume- averaged purging and sampling method at Duke Energy Ash Basin Groundwater Assessment Program facilities. 2.0 GENERAL CONSIDERATIONS Potential hazards associated with the planned tasks shall be thoroughly evaluated prior to conducting field activities. The Ready-To-Work Plan developed for each facility provides, among other items, a description of potential hazards and associated safety and control measures. Sampling personnel must wear powder-free nitrile gloves or equivalent while performing the procedures described in this SOP. Specifically, gloves must be worn while preparing sample bottles, preparing and decontaminating sampling equipment, collecting samples, and packing samples. At a minimum, gloves must be changed prior to the collection of each sample, or as necessary to prevent the possibility of cross-contamination with the sample, the sample bottles, or the sampling equipment. Field sampling equipment shall be decontaminated in accordance with the Decontamination of Equipment SOP (Appendix A) prior to use. Although sampling should typically be conducted from least to most impacted location, field logistics may necessitate other sample collection priorities. When sampling does not proceed from least to most impacted location, precautions must be taken to ensure that appropriate levels of decontamination are achieved. An example of equipment needed to properly conduct low-flow purging and sampling or volume- averaged groundwater purging and sampling is listed on the example checklist in Table 1 (Appendix B). If a portable generator is used to power the purge pump, it shall be attempted to be located downwind of the well being sampling to avoid cross-contamination of the sample with exhaust from the generator motor. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 2 3.0 PROCEDURES The following sections describe the general operating procedures and methods associated with groundwater sampling. Any variation in these procedures must be approved by the Project Manager (PM) and Quality Assurance/Quality Control (QA/QC) Lead and must be fully documented. Field work cannot progress until deviations are approved or resolved. 3.1 Pre-Job Preparation The information listed below may be reviewed prior to sampling activities, if available, and can be beneficial on-site for reference in the field as necessary: • A list of the monitoring wells to be sampled; • Information describing well location, using site-specific or topographic maps or Global Positioning System (GPS) coordinates and descriptions tied directly to prominent field markers; • A list of the analytical requirements for each sampling location; • Boring logs and well construction details, if available; • Survey data that identify the documented point of reference (V-notch or other mark on well casing) for the collection of depth-to-groundwater and total well depth measurements; • Previous depth-to-groundwater measurements; • Previous pump placement depths (dedicated pumps as well as portable pumps) for each sampling location, if available; • Previous pump settings and pumping and drawdown rates, if available; and • Previous analytical results for each monitoring well, if known. The information above is useful when determining the sampling order, pump intake depth, and purge and recharge rates, and can facilitate troubleshooting. The following activities should be completed prior to mobilizing to the site: • Obtain equipment necessary for completing the sampling activities (see the example checklist in Table 1). • Ensure appropriate laboratory-provided bottles are available for both the required analyses and for QC samples and that there has been thorough coordination with the analytical laboratory. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 3 • Obtain site-specific maps or GPS coordinates showing clearly marked monitoring well locations or groundwater sample points. • Review the project work control documents such as the Ready-To-Work Plan, and appropriate SOPs in an effort to determine project-specific sampling requirements, procedures, and goals. • Verify that legal right-of-entry has been obtained and site access has been granted, where required. • Instruct the field team to avoid discussing project data with the public and to refer questions to the Project Manager. 3.2 Water-Level Measurements Prior to pump placement, an initial depth-to-water level and total well depth should be measured. For monitoring wells screened across the water table, this measurement shall be used to determine the required depth to the pump intake (typically, approximately the mid-point of the saturated screen length for low-flow purging and sampling). The procedure for measuring water levels may include the following: 1) Inspect the well head area for evidence of damage or disturbance. Record notable observations in the field logbook. 2) Carefully open the protective outer cover of the monitoring well noting the presence of bee hives and/or spiders, as these animals are frequently found inside well covers. Remove any debris that has accumulated around the riser near the well plug. If water is present above the top of the riser and well plug, remove the water prior to opening the well plug. Do not open the well until the water above the well head has been removed. 3) If practical, well plugs shall be left open for approximately five minutes to allow the static water level to equilibrate before measuring the water level (if well plugs are vented, then a waiting period is not applicable). 4) Using an electronic water-level indicator accurate to 0.01 feet, determine the distance between the established point of reference (usually a V-notch or indelible mark on the well riser) and the surface of the standing water present in the well. Record these data in the field logbook. Repeat this measurement until two successive readings agree to within 0.01 feet. 5) Using an electronic water-level indicator accurate to 0.01 feet, determine the distance between the established point of reference (usually a V-notch or indelible mark on the well riser) and the bottom of the well. Note that there should not be considerable slack in the water-level indicator cable. Record these data in the field logbook. Repeat this measurement until two successive readings agree to within 0.01 feet. 6) If the monitoring well has the potential to contain non-aqueous phase liquids (NAPLs), probe the well for these materials using an optical interface probe. These wells will be attempted to be identified by the Project Manager prior to Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 4 mobilizing to the well. If NAPL is present, consult the Project Manager for direction on collecting samples for analysis. In general, do not collect groundwater samples from monitoring wells containing NAPL. 7) Decontaminate the water-level indicator (and interface probe, if applicable) and return the indicator to its clean protective casing. 3.3 Well Purging Wells must be purged prior to sampling to ensure that representative groundwater is obtained from the water-bearing unit. If the well has been previously sampled in accordance with this sampling plan, then the depth to the pump intake and the pumping rates should be duplicated to the extent possible during subsequent sampling events. Section 3.3.1 provides a description of low-flow well purging, and Section 3.3.2 provides a description of volume-averaging well purging (in the case it’s needed). 3.3.1 Low-Flow Well Purging Adjustable-rate peristaltic, bladder and electric submersible pumps are preferred for use during low-flow purging and sampling activities. Since purging and sampling are joined together as one continuous operation, care will be given to pump selection as it applies to the specific well conditions and analytes to be tested. Note that a ball valve (or similar valve constructed of polyethylene) may need to be installed to reduce the flow rate to the required level. The low-flow purging and sampling guidance is provided below: 1) Using the specific details of well construction and current water-level measurement, determine the pump intake set depth (typically the approximate mid-point of the saturated well screen or other target sample collection depth adjacent to specific high-yield zones). 2) Attach tubing and supporting rope (if applicable) to the pump and very slowly lower the unit until the pump intake depth is reached. Measure the length of supporting rope required, taking into account the pump length, to attain the required depth. Record the depth to the pump intake in the field logbook. Notes: 1) Sampling shall use new certified-clean disposable tubing. 2) Rope shall be clean, unused, dedicated nylon rope. If a pump is to remain in a well as part of a separate monitoring program, then the rope shall be suspended within the well above the water column for future use. If the pump is removed after sample collection, the rope shall be disposed. 3) After allowing time for the water level to equilibrate, slowly lower the electronic water-level probe into the well until the probe contacts the groundwater. Record the water level in the field logbook. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 5 4) If the well has been previously sampled using low-flow purging and sampling methods, begin purging at the rate known to induce minimal drawdown. Frequently check the drawdown rate to verify that minimum drawdown is being maintained. If results from the previous sampling event are not known, begin purging the well at the minimum pumping rate of approximately 100 milliliters per minute (mL/min) (EPA, July 1996). Slowly increase the pumping rate to a level that does not cause the well to drawdown more than about 0.3 feet, if possible. Never increase the pumping rate to a level in excess of 500 mL/min (approximately 0.13 gallon per minute [gpm]). Record the stabilized flow rate, drawdown, and time on the field data sheets. 5) If the drawdown does not stabilize at 100 mL/min (0.026 gpm), continue pumping. However, in general, do not draw down the water level more than approximately 25% of the distance between the static water level and pump intake depth (American Society for Testing and Materials [ASTM], 2011). If the recharge rate of the well is lower than the minimum pumping rate but the drawdown is less than 25% of the distance between the static water level and pump intake depth after three volumes of well water are removed, then collect samples at this point even though indicator field parameters have not stabilized (EPA, July 1996). Commence sampling as soon as the water level has recovered sufficiently to collect the required sample volumes. Otherwise, the Volume-Averaging Well Purging method should be considered.Allow the pump to remain undisturbed in the well during this recovery period to minimize the turbidity of the water samples. Fully document the pump settings, pumping rate, drawdown, and field parameter readings on the Well Sampling / MicroPurge (Low Flow) Log in the field logbook. Note: For wells that either have very slow recharge rates, that draw down excessively (more than 25% of the distance between the static water level and pump intake depth) at the minimum pumping rate (100 mL/min or 0.026 gpm), or require a higher pumping rate (greater than 500 mL/min or 0.13 gpm) to maintain purging, the procedures described above may not apply. For these “special case” wells, the Field Team Leader shall seek guidance from the Project Manager about the appropriate purging and sampling methodologies to be employed (such as volume-averaged purging and sampling described in Section 3.3.2). 6) Once an acceptable flow rate has been established, begin monitoring designated indicator field parameters. Indicator parameters are pH, specific conductance, dissolved oxygen (DO), and turbidity. Although not considered purge stabilization parameters, temperature and oxidation reduction potential (ORP) will be recorded during purging. Base the frequency of the measurements on the time required to completely evacuate one volume of the flow through the cell to ensure that independent measurements are made. For example, a 500-mL cell in a system pumped at a rate of 100 mL/min is evacuated in five minutes; accordingly, measurements are made and recorded on the field data form (Appendix C) approximately five minutes apart. Indicator parameters have stabilized when three consecutive readings, taken at three to five-minute intervals, meet the following criteria (EPA, March 2013): Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 6 • pH ± 0.1 standard unit • Specific Conductance ± 5% in µS/cm • DO ± 0.2 mg/L or 10% saturation • Turbidity less than 10 NTUs The target for monitoring turbidity is readings less than ten nephelometric turbidity units (NTUs). In some instances, turbidity levels may exceed the desired turbidity level due to natural aquifer conditions (EPA, April 1996). When these conditions are encountered, the following guidelines shall be considered. • If turbidity readings are slightly above 10 NTU, but trending downward, purging and monitoring shall continue. • If turbidity readings are greater than 10 NTU and have stabilized to within 10% during three successive readings, attempt to contact the Project Manager prior to collecting the groundwater sample. • If turbidity readings are greater than 10 NTU and are not stable, well sampling shall be based upon stabilization of more critical indicator parameters (such as dissolved oxygen) without attainment of the targeted turbidity. Attempt to contact the Project Manger if this condition is encountered prior to collecting the groundwater sample. • If after 5 well volumes or two hours of purging (whichever is achieved first), critical indicator field parameters have not stabilized, discontinue purging and collect samples. Fully document efforts used to stabilize the parameters (such as modified pumping rates). Note: While every effort should be taken to ensure that indicator parameters stabilize, some indicator parameters are more critical with respect to certain contaminant types. It is important to identify which indicator parameters are most important to the project prior to commencement of field activities so that unnecessarily protracted purge times can be avoided. For example, the critical indicator parameter associated with metals is turbidity. While it is desirable to sample wells when turbidity measurements are less than 5 NTU, Duke Energy recognizes that these values may not be attainable. Duke Energy, and its sub- consultants, have taken multiple steps (e.g., use of pre-packed screens, carefully selected sand pack, etc.) to alleviate the potential for elevated turbidity in newly installed wells. However, even with these conservative and targeted well installation specifications, other naturally occurring conditions (e.g., iron fluctuation) may prevent sampling of wells at turbidity values less than 5 NTU. Following sample collection and laboratory data evaluation, Duke Energy may review these data with respect to turbidity values to determine if additional well development is needed or if well construction has affected groundwater conditions. It may be necessary to redevelop wells from time to time to minimize Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 7 sample turbidity. Fine silt and clay can collect at the base of a well over time. The effect on future sampling events can be reduced by lowering the tubing or pump to the bottom of the well (after all the groundwater samples have been collected) and pumping until the purge water from the bottom of the well screen is clear. Note: If purging of a well does not result in turbidity measurements of 10 NTU or less, the field sampler shall alert the Project Manager. The sampling team will assess options to reduce the turbidity as soon as possible. There are a variety of water-quality meters available that measure the water quality parameters identified above. A multi-parameter meter capable of measuring each of the water quality parameters referenced previously (except for turbidity) in one flow-through cell is required. Turbidity shall be measured using a separate turbidity meter or prior to flow into the flow through cell using an inline T-valve, if using one multi-meter during purging. The water quality meter (and turbidity meter) shall be calibrated as per manufacturer’s instructions. Calibration procedures shall be documented in the project field logbook including calibration solutions used, expiration date(s), lot numbers, and calibration results. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 8 3.3.2 Volume-Averaging Well Purging For wells that either have very slow recharge rates, that draw down excessively at the minimum pumping rate (100 mL/min or 0.026 gpm), or require a higher pumping rate (greater than 500 mL/min or 0.13 gpm) to maintain purging (i.e., low-flow well purging and sampling is not appropriate), the volume-averaging well purging and sampling method may be used. The Field Team Leader shall seek approval from the Project Manager before utilizing the volume-averaging method instead of the low-flow method. 3.3.2.1 CALCULATE PURGE VOLUMES Based on the depth-to-water (DTW) and total depth (TD) measurements, the volume of standing water in the well must be calculated using the following procedures. 1) Subtract DTW from TD to calculate the length of the standing water column (Lwc) in the well. ܶܦ െ ܦܹܶ ൌ ܮ௪௖ 2) Multiply the length of the standing water column by the volume calculation (gallon per linear foot of depth) based on the inner casing diameter (see example list below) to determine the total standing water volume; this represents one well volume. ܸ௪ = ܮ௪௖ ൈ2ߨݎଶ 1-inch well = 0.041 gallon per linear foot 2-inch well = 0.163 gallon per linear foot 4-inch well = 0.653 gallon per linear foot 6-inch well = 1.469 gallons per linear foot 8-inch well = 2.611 gallons per linear foot 3) Multiply the well volume calculated in the previous step by three and five to obtain the approximate respective total purge volume (the target purge volume is between three and five standing well volumes). For wells with multiple casing diameters (such as open bedrock holes), calculate the volume for each segment. Take the sum of the values and multiply by three and five to determine the minimum and maximum purge volumes, respectively. 4) Fully document the volume calculation in the field logbook or on the Groundwater Sampling Field Sheets. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 9 3.3.2.2 PURGE THE MONITORING WELL Determine the appropriate pump to be used for purging—the preferred and most commonly used methods involve the use of a surface centrifugal or peristaltic pump whenever the head difference between the sampling location and the water level is less than the limit of suction and the volume to be removed is reasonably small. Where the water level is below the limit of suction or there is a large volume of water to be purged, use the variable speed electric submersible pump as the pump of choice (EPA, 2013). In some cases (shallow wells with small purge volumes), purging with a bladder pump may be appropriate. Once the proper pump has been selected: 1) Set the pump immediately above the top of the well screen or approximately three to five feet below the top of the water table (EPA, 2013). 2) Lower the pump if the water level drops during purging. Note: Use new certified-clean disposable tubing for purging and sampling. Note: Although volume-averaged sampling involves purging a specified volume of water (such as three to five well volumes) rather than basing purge completion on the stabilization of water quality indicator parameters, measuring and recording water-quality indicator parameters during purging provides information that can be used for assessment and remedial decision-making purposes. Indicator parameters are pH, specific conductance, DO, and turbidity as described in Section 3.3.1. Temperature and ORP will also be recorded during purging. 3) During well purging, monitor the discharge rate using a graduated cylinder or other measuring device, water-quality indicator parameters (if desired), and DTW as follows: • Initially, within approximately three minutes of startup, • Approximately after each well volume is purged, and then • Before purge completion. 4) Record pump discharge rates (mL/ min or gpm) and pump settings in the field logbook. Also, record any changes in the pump settings and the time at which the changes were made. 5) Maintain low pumping rates to avoid overpumping or pumping the well to dryness, if possible. If necessary, adjust pumping rates, pump set depth, or extend pumping times to remove the desired volume of water. 6) Upon reaching the desired purge water volume, turn off the purge pump. Do not allow the water contained in the pump tubing to drain back into the well when the pump is turned off. Use an inline check valve or similar device, or if using a peristaltic pump, remove the tubing from the well prior to turning off the pump. It is Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 10 preferred to collect samples within two hours of purging, but acceptable for collection up to 24 hours of purging. Do not collect samples after 24 hours of purging. Note: The removal of three to five well volumes may not be practical in wells with slow recovery rates. If a well is pumped to near dryness at a rate less than 1.9 L/min (0.5 gpm), the well shall be allowed to completely recover prior to sampling. If necessary, the two-hour limit may be exceeded to allow for sufficient recovery, but samples should be collected within 24 hours of purge completion. 3.4 Sampling 3.4.1 Low-Flow Sampling Following are the procedures for the collection of low-flow groundwater samples. These procedures apply to sample collection for unfiltered and filtered samples using a 0.45 micron filter. See Appendix A for use of 0.1 micron filtered samples. 1) Record the final pump settings in the field logbook prior to sample collection. 2) Measure and record the indicator parameter readings prior to sample collection on both the stabilization form and in the field logbook. 3) Record comments pertinent to the appearance (color, floc, turbid) and obvious odors (such as sulfur odor or petroleum hydrocarbons odor) associated with the water. 4) Arrange and label necessary sample bottles and ensure that preservatives are added, as required. Include a unique sample number, time and date of sampling, the initials of the sampler, and the requested analysis on the label. Additionally, provide information pertinent to the preservation materials or chemicals used in the sample. 5) Collect samples directly from pump tubing prior to the flow-through cell or via the in-line T-valve used for turbidity measurements (as described Section 3.3.1 (6) above). Ensure that the sampling tubing remains filled during sampling and attempt to prevent water from descending back into the well. Minimize turbulence when filling sample containers, by allowing the liquid to run gently down the inside of the bottle. Fill the labeled sample bottles in the following order: • Metals and Radionuclides, • Filtered Metals and Radionuclides, if required, and then • Other water-quality parameters. 6) Seal each sample and place the sample on ice in a cooler to maintain sample temperature preservation requirements. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 11 7) Note the sample identification and sample collection time in field logbook and on Chain-of-Custody form. 8) Once sampling is complete, retrieve the sample pump and associated sampling equipment and decontaminate in accordance with procedures outlined in the Decontamination of Equipment SOP (Appendix A). 9) Close and secure the well. Clean up and remove debris left from the sampling event. Be sure that investigation-derived wastes are properly containerized and labeled, if applicable. 10) Review sampling records for completeness. Add additional notes as necessary. 3.4.2 Sampling after Volume-Averaging Purge The procedures described below are for the collection of groundwater samples after a volume-averaged purge has been conducted. Volume- averaging purge methods are described in Section 3.3.2. 1) If sampling with a pump, care shall be taken to minimize purge water descending back into the well through the pump tubing. Minimize turbulence when filling sample containers by allowing the liquid to run gently down the inside of the bottle. Fill the labeled sample bottles in the following order: • Metals and Radionuclides, • Filtered Metals and Radionuclides, if required, and then • Other water-quality parameters. 2) If sampling with a bailer, slowly lower a clean, disposable bailer through the fluid surface. Retrieve the bailer and fill the sample bottles as described above. Care shall be taken to minimize disturbing the sample during collection. 3.5 Sample Handling, Packing, and Shipping Samples shall be marked, labeled, packaged, and shipped in accordance with the sections outline below. 3.5.1 Handling The samples will be stored in coolers for transport to the site. Collected samples will be placed on ice in the sampling coolers for pickup or transport to the laboratory for analysis. 3.5.2 Sample Labels All sample containers will be new, laboratory cleaned and certified bottles. The bottles will be properly labeled for identification and will include the following information: • Project Site/ID Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 12 • Sample identifier (Well ID) • Name or initials of sampler(s) • Date and time of collection • Analysis parameter(s)/method • Preservative 3.5.3 Chain-of-Custody Record Sample transport and handling will be strictly controlled to prevent sample contamination. Chain-of-Custody control for all samples will consist of the following: • Sample containers will be securely placed in coolers (iced) and will remain under the supervision of project personnel until transfer of the samples to the laboratory for analysis has occurred. • Upon delivery to the laboratory, the laboratory director or his designee will sign the Chain-of-Custody control forms and formally receive the samples. The laboratory will ensure that proper refrigeration of the samples is maintained. The Chain-of-Custody document contains information which may include: • Client name • Client project name • Client contact • Client address • Client phone/fax number • Sampler(s) name and signature • Signature of person involved in the chain of possession • Inclusive dates of possession • Sample identification • Sample number • Date & time of collection • Matrix • Type of container and preservative • Number of containers • Sample type - grab or composite • Analysis parameter(s)/ method • Internal temperature of shipping container upon opening in the laboratory 3.6 Field Quality Control Samples Field quality control involves the routine collection and analysis of QC blanks to verify that the sample collection and handling processes have not impaired the quality of the samples. Duke Energy | Low Flow Groundwater Sampling Plan3.0 PROCEDURES 13 • Equipment Blank – The equipment blank is a sample of deionized water, which is taken to the field and used as rinse water for sampling equipment. The equipment blank is prepared like the actual samples and returned to the laboratory for identical analysis. An equipment blank is used to determine if certain field sampling or cleaning procedures result in cross-contamination of site samples or if atmospheric contamination has occurred. One equipment blank sample will be prepared per day or per 20 groundwater samples, whichever is more frequent. Field and laboratory QA/QC also involves the routine collection and analysis of duplicate field samples. These samples are collected at a minimum rate of approximately one per 20 groundwater samples per sample event. A field duplicate is a replicate sample prepared at the sampling locations from equal portions of all sample aliquots combined to make the sample. Both the field duplicate and the sample are collected at the same time, in the same container type, preserved in the same way, and analyzed by the same laboratory as a measure of sampling and analytical precision. 3.7 Field Logbook Documentation Field logbooks shall be maintained by the Field Team Leader to record daily activities. The field logbook may include the following information for each well: • Well identification number • Well depth • Static water level depth • Presence of immiscible layers (yes – no) • Estimated well yield, if known • Purge volume and purge pumping rate • Time well purge began and ended • Well evacuation procedure and equipment • Field analysis data • Climatic conditions including air temperature • Field observations on sampling event • Well location • Name of collector(s) • Date and time of sample collection • Sampling procedure • Sampling equipment • Types of sample containers used and sample identification numbers • Preservative used Duke Energy | Low Flow Groundwater Sampling Plan4.0 REFERENCES 14 The Field Team Leader shall review the field logbook entries for completeness and accuracy. The Field Team Leader is responsible for completion of the required data collection forms. Example field logs are in Appendix C. 3.8 Decontamination and Waste Management Sampling equipment decontamination shall be performed in a manner consistent with the Decontamination of Equipment SOP (Appendix A). Decontamination procedures shall be documented in the field logbook. Investigation-derived wastes produced during sampling or decontamination shall be managed in accordance with State and Station-specific rules for disposal of wastes. 4.0 REFERENCES American Society for Testing and Materials (ASTM). Standard Practice for Low-Flow Purging and Sampling for Wells and Devices Used for Ground-Water Quality Investigations, D 6771-02. 2011. Test Methods for Evaluating Solid Waste - Physical/Chemical Methods (SW-846), Third Edition. U.S. Environmental Protection Agency. Update I, II, IIA, IIB, III, IIIA, IVA and IVB. United States Environmental Protection Agency (EPA), Office of Research and Development, Office of Solid Waste and Emergency Response. Ground Water Issue, “Low-Flow (Minimal Drawdown Sampling Procedures). Document Number EPA/540/S-95/504,” April 1996. U.S. EPA. Region 4, Groundwater Sampling Operating Procedure. Document Number SESDPROC-301-R3, November 2013. U.S. EPA. Region I, Low Stress (Low Flow) Purging and Sampling Procedure for the Collection of Ground Water Samples from Monitoring Wells, Revision 2, July 1996. Duke Energy | Low Flow Groundwater Sampling PlarDecontamination of Equipment SOP 15 A Decontamination of Equipment SOP Duke Energy | Low Flow Groundwater Sampling PlarPurpose & Application 16 1.0 Purpose & Application This procedure describes techniques meant to produce acceptable decontamination of equipment used in field investigation and sampling activities. Variations from this SOP should be approved by the Project Manager prior to implementation and a description of the variance documented in the field logbook. 2.0 Equipment & Materials • Decontamination water, • Alconox detergent or equivalent non-phosphate detergent • Test tube brush or equivalent • 5-gallon bucket(s) • Aluminum foil • Pump 3.0 Procedure 3.1 Decontamination of Non-Disposable Sampling Equipment Decontamination of non-disposable sampling equipment used to collect samples for chemical analyses will be conducted prior to each sampling as described below. Larger items may be decontaminated at the decontamination pad. Smaller items may be decontaminated over 5-gallon buckets. Wastewater will be disposed in accordance with applicable State and Station-specific requirements. 1. Alconox detergent or equivalent and water will be used to scrub the equipment. 2. Equipment will be first rinsed with water and then rinsed with distilled/deionized water. 3. Equipment will be air dried on plastic sheeting. 4. After drying, exposed ends of equipment will be wrapped or covered with aluminum foil for transport and handling. 3.2 Decontamination of Field Instrumentation Field instrumentation (such as interface probes, water quality meters, etc.) will be decontaminated between sample locations by rinsing with deionized or distilled water. If visible contamination still exists on the equipment after the rinse, an Alconox (or equivalent) detergent scrub will be added and the probe thoroughly rinsed again. Decontamination of probes and meters will take place in a 5-gallon bucket. The decontamination water will be handled and disposed in accordance with applicable State and Station-specific requirements. Duke Energy | Low Flow Groundwater Sampling Plar3.0 Procedure 17 3.3 Decontamination of Groundwater Sampling Equipment Non-disposable groundwater sampling equipment, including the pump, support cable and electrical wires in contact with the sample will be thoroughly decontaminated as described below: 1. As a pre-rinse, the pump will be operated in a deep basin containing 8 to 10 gallons of water. Other equipment will be flushed with water. 2. The pump will be washed by operating it in a deep basin containing phosphate- free detergent solution, such as Alconox, and other equipment will be flushed with a fresh detergent solution. Detergent will be used sparingly, as needed. 3. Afterwards, the pump will be rinsed by operating it in a deep basin of water and other equipment will be flushed with water. 4. The pump will then be disassembled and washed in a deep basin containing non-phosphate detergent solution. All pump parts will be scrubbed with a test tube brush or equivalent. 5. Pump parts will be first rinsed with water and then rinsed with distilled/deionized water. 6. For a bladder pump, the disposable bladder will be replaced with a new one for each well and the pump reassembled. 7. The decontamination water will be disposed of properly. 3.4 Materials from Decontamination Activities All wastewater and PPE generated from decontamination activities will be handled and disposed in accordance with applicable State and Station-specific requirements. Duke Energy | Low Flow Groundwater Sampling PlarSampling Equipment Check List – Table 1 18 B Sampling Equipment Check List – Table 1 Duke Energy | Low Flow Groundwater Sampling PlarSampling Equipment Check List – Table 1 19 Table 1: Suggested Groundwater Sampling Equipment & Material Checklist Item Description Check Health & Safety Nitrile gloves Hard hat Steel-toed boots Hearing protection Field first-aid kit Fire Extinguisher Eyewash Safety glasses Respirator and cartridges (if necessary) Saranex™/Tyvek® suits and booties (if necessary) Paperwork Health and Safety Plan Project work control documents Well construction data, location map, field data from previous sampling events Chain-of-custody forms and custody seals Field logbook Measuring Equipment Flow measurement supplies (for example, graduated cylinder and stop watch) Electronic water-level indicator capable of detecting non-aqueous phase liquid Sampling Equipment GPS device Monitoring well keys Tools for well access (for example, socket set, wrench, screw driver, T-wrench) Laboratory-supplied certified-clean bottles, preserved by laboratory (if necessary) Appropriate trip blanks and high-quality blank water Sample filtration device and filters Submersible pump, peristaltic pump, or other appropriate pump Appropriate sample and air line tubing (Silastic®, Teflon®, Tygon®, or equivalent) Stainless steel clamps to attach sample lines to pump Pump controller and power supply Oil-less air compressor, air line leads, and end fittings (if using bladder pump) In-line groundwater parameter monitoring device (for example, YSI-556 Multi-Parameter or Horiba U-52 water quality meter) Turbidity meter Bailer Calibration standards for monitoring devices Duke Energy | Low Flow Groundwater Sampling PlarField Logbook/Data Sheets 20 C Field Logbook/Data Sheets Duke Energy | Low Flow Groundwater Sampling PlarField Logbook/Data Sheets 21 Groundwater Potentiometric Level Measurement Log Well Number Time Depth to Water (ft)* Depth to Bottom (ft)* Water Column Thickness (ft) Reference Point Elevation (ft, MSL) Potentiometric Elevation (ft, MSL) Remarks Field Personnel: Checked By: * - Measurements are referenced from the top of the PVC inner casing (TOC) for each respective monitoring well. TOCs shall be surveyed by a Professional Land Surveyor and referenced to NAVD88. Duke Energy | Low Flow Groundwater Sampling PlarField Logbook/Data Sheets 22 Well Sampling / MicroPurge Log Project Name: Sheet: of Well Number: Date: Well Diameter: Top of Casing Elevation (ft, MSL): Pump Intake Depth (ft): Total Well Depth (ft): Recharge Rate (sec): Initial Depth to Water (ft): Discharge Rate (sec): Water Column Thickness (ft): Controller Settings: Water Column Elevation (ft, MSL): Purging Time Initiated: 1 Well Volume (gal): Purging Time Completed: 3 Well Volumes (gal): Total Gallons Purged: WELL PURGING RECORD Time Volume Purged (gallons) Flow Rate (mL/min) Depth to Water (ft) Temperature (°C) pH (s.u.) Specific Conductance (mS/cm) Dissolved Oxygen (mg/L) ORP (mV) Turbidity (NTU) Comments      Stabilization Criteria Min. 1 Well Volume + 3°C + 0.1 + 3% + 10% + 10 mV < 5 NTU or + 10 % if > 5 NTU GROUNDWATER SAMPLING RECORD Sample Number Collection Time Parameter Container Preservative Duke Energy | Low Flow Groundwater Sampling PlarField Logbook/Data Sheets 23 DAILY FIELD REPORT Project Name: Field Manager: Field Personnel: Date: Weather: Labor Hours Equipment Materials Field Observations: Submitted by: Reviewedby: