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HomeMy WebLinkAboutNC0001422_5-Sutton GAP DENR Approval 2_6_2015_201508050 IF LWWJ CDEN� North Carolina Department of Environment and Natural Resources Pat McCrory Governor February 6, 2015 Mr. Harry Sideris Senior Vice -President Environment, Health, and Safety Duke Energy 526 South Church Street Mail Code EC3XP Charlotte, NC 28202 Re: L.V. Sutton Energy Complex NPDES Permit No. NC0001422 — New Hanover County, North Carolina Conditional Approval of Revised Groundwater Assessment Work Plan Dear Mr. Sideris: Donald R. van der Vaart Secretary On December 31, 2014, the Division of Water Resources (Division) received the revised Groundwater Assessment Plan (GAP) for the above listed facility. The revised GAP was submitted in response to the Division's Review of Groundwater Assessment Work Plan letter dated November 4, 2014 regarding requirements of the Coal Ash Management Act 2014—G.S.130A-309.209(a). A review of the plan has been completed and several deficiencies or items requiring clarification were noted. In order to keep the site assessment activities on a timely schedule, the Division has approved the revised Groundwater Assessment Plan under the condition that the following deficient items are addressed in the Groundwater Assessment Report: • Comment Section 7. 1. Subsurface Exploration: The present version of the GAP does not provide any description of how the confining unit will be evaluated as directed in General Comment #3 of the Division's Review of Groundwater Assessment Work Plan letter dated November 4, 2014. In order to refine the conceptual model at the site, install an adequate amount of borings to delineate the extent and thickness of the confining unit. In addition, conduct tests to evaluate the vertical gradient across the confining unit. • Comment Section 7.2 Ash Pore Water and Groundwater Sampling and Analysis: Text on pages 41 and 42 refers to proposed sampling for radium at wells MW-44SA and BW -2S, which are not listed in tables or maps. Clarify this situation before sampling or chose alternate sampling locations that can be documented. 1636 Mail Service Center, Raleigh, North Carolina 27699-1636 Phone: 919-807-64641 Internet: http://www.ncwater.org An Equal Opportunity 1 Affirmative Action Employer — Made in part by recycled paper • Comment Section 7.3.1 Water Quality Samples: Timing of stream sampling should be conducted with consideration of the tidal influence on the Cape Fear River in this area which is a transition zone between the riverine and estuarine environment (e.g. upstream samples should be taken during an outgoing tide to be more representative of upstream river conditions). In addition, technical direction that will serve as the basis of expectations for completion of the site assessment are provided at Attachment 1. Failure to address the deficient items stated above will result in Duke Energy not being in compliance with the stated statutes. Per G.S. 130A -309.209(a)(3) and (4), you must begin implementation of the revised GAP on February 16, 2015 and the Groundwater Assessment Report is due on August 5, 2015. It is our understanding that Duke Energy may have to obtain additional permits to facilitate installation of certain monitoring wells. In the event permits are needed for this purpose, Duke Energy should take all steps necessary consistent with the law to avoid delaying completion of the assessment report. If you have any questions, please contact Geoff Kegley at (910) 796-7328. Sincerely, S. Ja ti erman, P.G., Acting Director Division of Water Resources cc: WQROS — WiRO WQROS Central Files DENR Secretary - Don van der Vaart Synterra (Attn: Kathryn Webb) —148 River Street, Suite 220, Greenville, SC 29601 Attachment 1 Page 1 of 6 Duke Energy GAP Review Issues The items identified in this Groundwater Assessment Plan (GAP) review summary are provided for general discussion for the various parties to agree upon technical direction and content in the revised GAPs, comprehensive site assessments (CSAs), and corrective action plans (CAPS). Groundwater Monitoring 1. A schedule for continued groundwater monitoring is mandated by the Coal Ash Management Act 2014. An interim plan should include at least two rounds of groundwater samples collected and analyzed in 2015. The analytical results of the first round of data collected in 2015 would be included in the CSA report, while the results of the second round would be submitted as a CSA addendum. After CSA data can be evaluated, a plan for continued groundwater monitoring can be developed for implementation in 2016. 2. Sites impacted by inorganics are typically managed using a tiered site analysis which includes four elements as referenced in EPA/600/R-07/139: • Demonstration of active contaminant removal from groundwater, & dissolved plume stability; • Determination of the mechanism and rate of attenuation; • Determination of the long-term capacity for attenuation and stability of immobilized contaminants, before, during, and after any proposed remedial activities; and • Design of performance monitoring program, including defining triggers for assessing the remedial action strategy failure, and establishing a contingency plan. This reference and the framework described above should be used as applicable to meet the corrective action requirements found in 15A NCAC 02L.0106. 3. Because of uncertainty concerning the site's ability to attenuate contaminants over the long term given potentially changing geochemical conditions, there is a need to address the elements of the tiered site analysis described above and collect appropriate samples as part of the CSA, CAP development, and continued groundwater monitoring. 4. The Division of Water Resources (Division) Director is responsible for establishing background levels for COPCs in groundwater. This determination is based on information and data provided by the responsible party and may include formal statistical testing using background wells with at least four rounds of data. Wells identified as "background" are subject to periodic review based on a refined understanding of site chemistry and hydrogeologic conditions. In general, each facility must have a background well or wells screened or open to each of the dominant flow systems that occur at the site and are associated with groundwater contamination. Any questions concerning adequacy of background monitoring locations or conditions at the facilities should be directed to the Regional offices. Attachment 1 Page 2 of 6 5. Delineation of the groundwater contaminant plume associated with coal combustion residuals is a requirement of the investigation and if off-site monitoring wells are ultimately required to perform this task, then it is expected that these activities will be completed as part of the groundwater assessment activities and included in the final report. Documentation of the effort to gain off-site access, or right of way permits, will be provided if off-site access is denied or alternate means of assessing the area were not available within the allocated timeframe (such as within right-of-ways). Site Assessment Data Requirements and Sampling Strategy 1. Robust data collection is warranted to support timely completion of site assessments and subsequent corrective action plans because of the impending deadlines for completion of CSAs and CAPS, scale and geologic complexity of the sites, the challenges of modeling heterogeneous systems, and site proximity to potential human and sensitive ecosystem receptors. 2. Robust data collection will be focused along strategically positioned flowpath transect(s) - from ash pond source to potential receptor—as an efficient approach for model development (analytical, geochemical, groundwater flow, and transport) in support of risk assessment and CAP development. Data collected to support evaluation of site conditions along the flowpath transects should be located along or defensibly proximate to the modeled transects. 3. The dataset developed along proposed flowpath transects will include any information needed to determine constituent concentrations, conduct Kd tests, and perform batch geochemical modeling in multiple flow horizons as appropriate. This data will include a) solid phase sample collection for Kd measurement and batch geochemical modeling, inorganic analysis and speciation, and other parameters identified in General Comment #4 of the November 4, 2014 GAP comments issued by DWR, b) solution phase sample collection for total and dissolved inorganic analysis of total concentrations, small pore filtration for dissolved samples, etc., and c) slug, constant/falling head, and packer testing. The solid phase sample mineralogy, total concentration results, re-dox measurements, and other geochemical parameters will be used as input for equilibrium speciation calculations of redox sensitive constituents calculated by PHREEQC or similar program (EPA/540/5-92/018). This geochemical modeling will be performed to identify potential mineral phases, estimated species speciation and concentrations, and will be performed varying key solubility controlling parameters to predict mineral phases, speciation, and concentrations under varying conditions. Solid samples for Kd tests from locations where moderately to strongly reducing conditions are anticipated shall be frozen upon collection and tested in glove box conditions (EPA/600/R-06/112). Refer to EPA/600/R-07/139 Section III for the data collection and characterization needed to support the four -tiered analysis discussed above. 4. Speciations for groundwater and surface water samples should include Fe, Mn, and any COPCs whose speciation state may affect toxicity or mobility (e.g. As, Cr, Se, or others if applicable). This speciation will apply for groundwater samples collected at wells located along proposed Attachment 1 Page 3 of 6 flowpath transects and in wells where these constituents exceed 2L groundwater standards as well as for surface water samples collected within ash impoundments. 5. Solid phase samples shall be analyzed for: minerals present, chemical composition of oxides, hydrous Fe, Mn, and AL oxides content; moisture content; particle size analysis; plasticity; specific gravity; porosity; permeability, or other physical properties or analyses needed to provide input to a chosen model. The Division reserves the right to request analysis for organic carbon content, organic carbonate content (as appropriate if site conditions warrant), or ion exchange capacities, if needed to complete the site assessment process. 6. In addition to conducting the SPLP leachable inorganic compounds analysis for selected ash samples to evaluate the potential for leaching of constituents to groundwater, the leachable analysis should also be conducted for some soil samples from locations beneath the ash ponds, within the plume, and outside the plume to evaluate potential contributions from native soils. 7. In addition to collecting solid phase samples onsite for Kd procedures, soil samples should be also collected from unaffected soils within groundwater flow pathway to evaluate Kd(s) or hydrous ferrous oxide. 8. Rock samples for laboratory analyses should be collected as commented in General Comment 4 of the November 4, 2014 GAP comments issued by DWR. This GAP review comment indicated that the sample(s) collected from bedrock well soil and rock cores shall be analyzed, at a minimum, for the following: type of material, formation from which it came, minerals present, chemical composition as oxides, hydrous Fe, Mn, and Al oxides content, surface area, moisture content, etc.; however, these analyses were not mentioned in the GAP. The Division reserves the right to request analysis for organic carbon content, organic carbonate content, and ion exchange capacity if needed to complete the site assessment process. 9. The coal ash and soil analyte lists should match the groundwater analyte lists. 10. Total uranium analysis should be analyzed where total radium is analyzed for groundwater. 11. If analytical results from a seep sample exceed 2L standards, then the area in the vicinity of the sample location should be investigated for groundwater contamination. If analytical results from a surface water sample exceed 2B Standards, then the area in the vicinity of the sample location should be investigated for groundwater contamination. 12. Surface water/seep samples should be collected during basefl6w conditions and that the groundwater monitoring (WLs and sampling) should occur at about the same time. 13. Measurement of streamflow in selected perennial streams is expected as needed in support of simulation/calibration of flow and transport models; major rivers that serve as groundwater divides are not included in this expectation. Conceptual Model Elements 1. In the CSA report, data gaps remaining should be specifically identified and summarized. 2. Site heterogeneities should be identified and described with respect to: a) their nature, b) their scale and density, c) the extent to which the data collection successfully characterizes them, d) how the modeling accounts for them, e) and how they affect modeling uncertainty. Attachment 1 Page 4 of 6 3. The impact of data gaps and site heterogeneities should be described in relation to the elements developed in the Site Hydrogeologic Conceptual Model and Fate and Transport Model subsections. 4. For sites in the Piedmont or Mountains, the CSA Report should include a subsection within the Site Geology and Hydrogeology Section titled 'Structural Geology'. This section should describe: a) foliations, b) shear zones, c) fracture trace analysis, and d) other structural components anticipated to be relevant to flow and contaminant transport at the site. 5. Duke Energy will include a poster -sized sheet(s) (ANSI E) combining tabulated analytical assessment results (groundwater, surface water, and leachate samples); multiple sheets may be needed to present the data. This should be provided in addition to the individual analytical results tables that will be prepared for the CSA reports. Any questions concerning format or content of the analytical result summaries should be directed to the Regional offices. Geochemical Modeling I. The Division agrees that a geochemical model "coupled" to a 3-D fate and transport model is inappropriate given the size and complexity of the sites and the extremely large amount of data required to calibrate such a model. Rather, a "batch" geochemical model approach should be sufficient for successfully completing the site assessment and/or corrective action plan. 2. Samples collected for "batch" geochemical analysis should be focused along or defensibly proximate to flowpath transects. 3. To support successful batch geochemical modeling, dissolved groundwater samples collected along a contaminant flowpath transect should be obtained using a 0.1 um filter. This will help ensure a true dissolved phase sample. Note that the dissolved samples are for assessment purposes only and may not be used for purposes of compliance monitoring. If there is uncertainty about which areas/wells will be used in the batch geochemical modeling, the initial round of assessment sampling at the facility can utilize the 0.45 um filter until the contaminant flow path transects are selected. Once determined, Duke Energy can go back and re -sample the wells needed for geochemical modeling using the 0.1 um filter. It is recognized that the use of a 0.1 um filter will be difficult for wells with elevated turbidity; in this case, it is recommended that Duke Energy use two filters in series (the water initially passes through a 0.45 um filter to remove larger particles prior to passing through the 0.1 um filter). Information for a disposable 0.1um field filter designed specifically for sampling groundwater for metal analysis is provided at the following link: http://www.vosstech.com/index.php/products/fiIters. If field comparisons of 0.1 versus 0.45 micron filtration at several transect wells at a given site show no significant differences between the two methods, then 0.45 micron filters may be used for evaluating the dissolved phase concentrations at that site. 4. In support of the objectives of General Comment #2 of the November 4, 2014 GAP comments issued by DWR , Duke Energy should add a column titled 'relative redox' to the analytical results tables to record the geochemical conditions for that location/sample date. The redox determination should be based on observed DO, ORP, and any other relevant measures and presented for historic and new samples (wells, ash pore water, surface waters, etc.). Relative Attachment 1 Page 5 of 6 redox designations may include "iron reducing", "sulfate reducing", mildly oxidizing, moderately oxidizing, etc. and should be footnoted with a statement about the degree of confidence in the designation based on amount and quality of available data. 5. Duke Energy shall also evaluate: a) spatial geochemical trends across the facility and along selected flow paths, b) temporal geochemical trends where observable (such as for compliance boundary wells), along with the likely reason for the change (e.g. increase in seasonal recharge, pond de -watering and subsequent reversal of groundwater flow direction, inundation of well from river at flood stage, etc.) in support of the CAP. This evaluation step will require a comparison of geochemical conditions over time with rainfall data, notable ash capping, dewatering, disposal/removal, or other plant operations, etc. The quality of existing geochemical data will be evaluated using field notes, calibration records, and consistency in redox measurements (e.g. eH vs. raw ORP). Groundwater Models 1. The technical direction for developing the fate and transport modeling will follow guidelines found in Groundwater Modeling Policy, NCDENR DWQ, May 31, 2007, and discussions conducted between Duke Energy and their consultants with the Division. Ultimate direction for completion of fate and transport models will be provided by the Division. 2. The CAP Report should include a subsection within Groundwater Modeling Results titled 'Site Conceptual Model' that succinctly summarizes, for purposes of model construction, the understanding of the physical and chemical setting of the site and shall include, at a minimum: a) the site setting (hydrogeology, dominant flow zones, heterogeneities, areas of pronounced vertical head gradients, areas of recharge and discharge, spatial distribution of geochemical conditions across the site, and other factors as appropriate), b) source areas and estimated mass loading history, c) receptors, d) chemical behavior of COPCs, and f) likely retention mechanisms for COPCs and how the mechanisms are expected to respond to changes in geochemical conditions. 3. Modeling will be included in the Corrective Action Plan (CAP). The four -tiered analysis previously referenced and appropriate modeling should be conducted, and the mass flux calculations described in the EPA/600/R-07/139 should be performed. 4. The CAP Report shall provide separate subsections for reporting groundwater flow models and fate and transport models. 5. The CAP Report should include subsections within Groundwater Modeling Results titled 'Groundwater Model Development' that describes, for each chosen model: a) purpose of model, built-in assumptions, model extent, grid, layers, boundary conditions, initial conditions, and others as listed in Division guidance. Include in this section a discussion of heterogeneities and how the model(s) account for this (e.g. dual porosity modeling, equivalent porous media approach, etc.). Separate subsections should be developed for the groundwater flow model, fate and transport model, and batch geochemical models, respectively. 6. CAP Reports should include a subsection within Groundwater Modeling Results titled 'Groundwater Model Calibration' that describes, for each model used, the process used to Attachment 1 Page 6 of 6 calibrate the model, the zones of input and calibration variables (for example, hydraulic conductivities) that were used, the actual (measured) versus modeled results for all key variables, and others. Separate subsections should be developed for the groundwater flow model, fate and transport model, and batch geochemical model(s), respectively. 7. CAP Reports should include a subsection within Groundwater Modeling Results titled 'Groundwater Model Sensitivity Analysis' that describes, for each model used, the process used to evaluate model uncertainty, variable ranges tested, and the key sensitivities. Separate subsections should be developed for the groundwater flow model, fate and transport model, and batch geochemical model(s), respectively. Development of Kd Terms 1. Kd testing and modeling in support of CAP development should include all COPCs found above the NCAC ISA 02L .0106(8) standards in ash leachate, ash pore water, or compliance boundary well groundwater samples. 2. The selected Kd used in transport modeling often will profoundly affect the results. Duke Energy should acknowledge this concept and document within the transport modeling section(s) of the CAP all widely recognized limitations inherent in the estimation of the Kd term. Risk Assessment 1. Provide references for guidance and potential sampling methodology related to conducting a baseline ecological risk assessment or habitat assessment, if warranted. NCDENR North Carolina Department of Environment and Natural Resources Pat McCrory Donald R. van der Vaart Governor Secretary June 9, 2015 CIERTIFIED MAIL 7002 0860 0006 5836 0342 RETURN RECEIPT REQUESTED Mr. Harry Sideris Senior Vice -President Environment, Health and Safety Duke Energy 526 South Church Street Mail Code EC3XP Charlotte, NC 28202 Subject: Notice of Regulatory Requirements Title 15A North Carolina Administrative Code (NCAC) 02L.0106 L.V. Sutton Electric Plant New Hanover County Dear Mr. Sideris: Chapter 143, North Carolina General Statutes, authorizes and directs the Environmental Management Commission of the Department of Environment and Natural Resources to protect and preserve the water and air resources of the State. The Division of Water Resources (DWR) has the delegated authority to enforce adopted pollution control rules. On August 26, 2014, Duke Energy was issued a Notice of Violation and Notice of Intent to Enforce for violations of Title 15A NCAC Subchapter 02L.0202 Groundwater Quality Standards in monitoring wells located at or beyond the compliance boundary at the L.V. Sutton Electric Plant in New Hanover County. The violations of Groundwater Quality Standards for boron occurred in monitor wells MW -12, MW -19, MW -21C, MW -22C, MW -2313, MW -23C, MW -24B, MW -24C, and MW -31C located at or beyond the compliance boundary. Concentrations of boron were determined to be below detection levels in background wells. Recent sampling of water supply wells in the vicinity of the L.V. Sutton Electric Plant indicate elevated levels of boron approaching the 2L Standard of 700 ug/1. Specifically, the well located at 230 Sutton Lake Road had a boron concentration of 690 ug/1 and the well located at 235 Sutton Lake Road had a boron concentration of 600 ug/l. Although the complete site assessment is still ongoing, indications are that these water supply wells are down -gradient of the L.V. Sutton Electric Plant Ash Ponds. 1611 Mail Service Center, Raleigh, North Carolina 27699-1611 Phone: 919-707-8600 \ Internet: www.ncdenr.gov An Equal Opportunity 1 Affirmative Action Employer — Made in part by recycled paper Notice of Regulatory Requirements L.V. Sutton Electric Plant June 9, 2015 Title 15A NCAC 02L.0106(f) (2) states that corrective action required following discovery of the unauthorized release of contaminant to the surface or subsurface of the land, and prior to or concurrent with the assessment activities required in Paragraphs (c) and (d) of this rule, shall include, but is not limited to "Abatement, containment, or control of the migration of contaminants". In order to ensure protection of existing water supply wells, we hereby direct Duke Energy to take immediate action to control and prevent further migration of coal ash contaminants no later than July 9, 2015, pursuant to 15A NCAC 02L .0106(f). The DWR requests that Duke Energy provide the DWR with specific details concerning actions that Duke Energy plans to take to comply with this rule. These details may include, but not be limited to: (1) A description of the actions to be taken immediately by Duke Energy to abate, contain or control the migration of contaminants towards nearby water supply wells (2) Specific plans, including engineering details and permits where applicable, regarding these proposed actions (3) A monitoring plan for evaluating the effectiveness of these actions Failure to comply with the State's rules in the manner and time specified may result in the assessment of civil penalties and/or the use of other enforcement mechanisms available to the State. We appreciate your attention and prompt response in this matter. If you have questions, please feel free to contact me at (919) 707-9027. Sincerely, S. Ja i erman, P.G. Director. Division of Water Resources cc: Jim Gregson, WQROS WiRO Supervisor WQROS File Copy WQ Permitting, Permit File NC0001422 New Hanover County Health Department Page 2 of 2 NCDENR Forth Carolina Department ut Environment and Natural Resources Pat MUG[ uty (3overnor July 7, 2015 Duke Energy c/o: Mr. D. Edwin M. Sullivat-I P.O. Box 1006 Mail Code EC13K Charlotte, North Carolina 28201-1006 RE: Conditional Approval Letter Response L.V. Suttun Energy Complex New Hanover County, North Carolina Dear Mr. Sullivan: Uonala R. van der Vaart Seurtrtal y The vivision of Water Resources received Duke Energy's May 22, 2U 15 response to DENR's Conditional Approval dated February 6, 2015 for the L.V. Sutton Energy Coinplex Revised Groundwater Assessment Work Plan. Duke Energy provided responses ter the following sections: ® 7.1 Subsurface Exploration • 7.2 Ash Pure Waer and Groundwater Sampling and Analysis a 7.3.1 Water Quality Sara les Please incorporate and implement the agreed upon scvpe of work as related to the above conditions and outlined in Duke Energy's May 22, 2015 response. Additionally, Duke Energy requests guidance regadiiig solid phase testing methods for total organic carbonate content. ResearLh conducted by the Division has not identified a laboratory method for analysis of total orgaztic carbonate with respect to solid _phase samples. We appreciate Duke Energy bringing this issue to ut.0 attention. Since a suitable laboratory method for tutal urga.uic cai bursate has not been found, Duke Energy is not cumpclled to perfurm this analysis as part of the groundwater assessment at the L.V. Sunun Plzuit and other facilities located in the Coastal Plain. Should you have any questions or require additional information, please contact Geoff Kegley at 910-796-7328. Division -uT vvater RCsuarvCs - Water Quality Regional Operations Section - Wilmington Regional urm;e 1z1 Carainal Drive Ext., Wilmi,igton, NC 28405 Phone: 910-796-7215 \ Fax: 910-35U-z004t Internet: www.nt;denr.gov An Equal Opportunity 1 AMrMdd,. Nedon tMplOya — Made In part by recycled paper Mr. Sullivan July 7, 2015 Page 2 Sll1l:GiGly, i MorGIIa S ezr 1"Ph.u, Y.E Environm rogran Supervisor Division of Water Resources Water duality Regional Operations Wihnington Regional Office cc: Ricky Miller — Duke Energy John Toepfer — Duke Energy Kathy Webb — Syn I erra Corporation Steven Lmter — Div. Water Resources — CGntrul Office