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HomeMy WebLinkAboutNC0003425_Appx A - Regulatory Compliance_201710312017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra APPENDIX A REGULATORY CORRESPONDENCE NCDEQ Expectations Document (July 18, 2017) NCDEQ CSA Update Expectations – Check List – Roxboro Steam Electric Plant Zimmerman to Draovitch (September 1, 2017) NCDEQ Background Dataset Review (July 7, 2017) Revised Interim Monitoring Network (October 19, 2017) NCDENR NORR Letter (August 13, 2014) 2017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra NCDEQ Expectations Document (July 18, 2017) Page 1 of 8 DRAFT Review of Draft Final Updated CSA Table of Contents submitted by Duke Energy July 18, 2017 The Updated Comprehensive Site Assessment Report(CSAs) must meet the requirements of 02L .0106 (g), CAMA, and general guidelines provided in the Notice of Regulatory Requirements letter from DEQ to Duke on August 13, 2014. Pursuant to 02L .0106 (g), the CSAs shall:  Identify the source and cause of contamination,  Identify imminent hazards and document actions taken to mitigate them,  Identify all receptors,  Define the horizontal and vertical extent of contamination,  Understand all significant factors affecting contaminant transport,  Understand geological and hydrogeological factors influencing the movement, chemical, and physical character of the contaminants. It is the expectation that the CSA report be a stand-alone document that integrates, interprets, and presents all data/information collected to date. The table of contents submitted on 7/18/17 should be revised as necessary to ensure that the following comments are reflected in the CSA report. 1. Site history  Facility description, geographic setting, surrounding land use, permitting history, and compliance boundaries and permitted sampling, etc.  ash related history  history prior to Duke ownership  history of waste releases unrelated to coal ash 2. Identification of source areas1 3. Identification of potential receptors  Surface water o Is the SW used as drinking water supply? if so, what is the distance to intake?  Supply wells o Need map and table showing all receptors identified o Has each identified supply well been abandoned and connected to alternative permanent water? 1 Large ash basins or other waste areas may need to be divided into separate smaller source areas if, for example, contaminant transport is toward different sets of receptors. Where appropriate, some source areas may be strategically combined based on geographic proximity (for example, conjoining or overlapping source areas), common source characteristics and impacts, common receptors, and a shared proposed remedy. The Regional Office should be consulted when identifying source areas for purposes of CSA and CAP development. Page 2 of 8  Evaluation: Are COIs in supply wells above 2L/IMAC/background and sourced by ash? 4. Raw data collected to date  A separate orthophoto base map2 should be provided for each of the following: o All GW monitoring and supply wells  Show screened interval (ft) and most recent concentration of boron and COIs (ug/L) (use different color font for each flow unit) o All SW, seep, and effluent channel (permitted) sample locations  Show most recent results of boron and COIs (ug/L) o All SW locations sampled specifically to determine whether contaminated GW is causing 2B violations  Show most recent results of boron and COIs (ug/L); use bold font for values that exceeded 2B standards (ug/L) o All solid phase sample locations, to include ash, soil, and sediment locations  Show sample depth (ft bls) and corresponding concentration of COIs (mg/kg) o Location, flow unit, screened/open interval (ft bls), and value (ft/d) of hydraulic conductivity (k) measurements (use different color font for each flow unit) o Location, depth (ft bls), and flow unit of soil-water pairs (use different color font for each flow unit) o Location, depth (ft bls), flow unit, and value of HFO measurements (use different color font for each flow unit) o Location, depth (ft bls), and flow unit of sorption coefficient (Kds) measurements (use different color font for each flow unit) o Location, flow unit, and value of pH measurements (use different color font for each flow unit) o Location, flow unit, and value of Eh measurements (mV) (use different color font for each flow unit) o Location of vertical gradient calculations between shallow/TZ unit and BR unit, showing value (+ is downward gradient, - is upward gradient)  Cross section maps showing ash position, hydrostratigraphy, screen/open intervals, water level, and groundwater boron and COI concentrations (ug/L) o inset should show location (in plan view) of the cross section  Summary data tables: o properties for ash, fill, alluvium, soil/saprolite, deep, and bedrock units, as applicable, including:  Porosity  Specific storage  Permeability (field, lab, historic)  Mineralogy and oxides  Physical Methodology, computations, etc. may be referenced, as applicable o hydraulic conductivities (k, in ft/d), sorted by flow unit, along with well identifier, flow unit, and screened/open interval (ft bls) o sorption coefficients (Kd), sorted by COI then flow unit, along with boring location identifier, flow unit, and depth (ft bls) 2 All base maps should include2 to 4 foot topographic contours, all surface water features, all jurisdictional wetlands, all source areas along with waste boundaries and compliance boundaries if applicable, all monitor wells, and, where scale allows, all supply wells. Page 3 of 8  Appendices o Raw data tables showing chemistry results for:  all GW, SW, and seep sample events (appendix and digital excel file)  all ash, soil, sediment, and whole rock chemistry results (appendix and digital excel file)  all SPLP samples (appendix and digital excel file)  lat/long, flow unit (if applicable), etc. should be included for each sample location  current “master spreadsheet” format may be used  lab QC data may be referenced if it has already been provided in a separate report o Summary table of monitor well construction details showing well, location (decimal degree lat/long), screen/open interval, depth to water, date installed, flow unit being monitored, date abandoned if applicable, etc. o Water level measurements from all wells and current and historical measurement events (appendix and digital excel file)  List of wells that were dry during sampling or measurement attempts, along with its flow unit, screened/open interval, and date o Sorption coefficient testing - methodology, raw data, and computations may be referenced o Boring logs and well construction records  Include all assessment, historic, CCR, or other wells installed to date  Each log should be quality controlled for accuracy and include static WL information. o Geophysical logs, rose diagrams, lineament map o Soil and rock photos o Most recent pre-ash basin USGS topographic map, with superimposed source areas o Screening level risk assessment  Human health  Ecological o Flow and transport model o Geochemical model o GW-SW mixing model, if applicable 5. Site conceptual model  Overview of the major components, including source(s), hydrologic boundaries, migration pathway(s), receptors, etc.  Regional geology and how it is affecting GW flow, GW quality, and contaminant transport at the site  Hydrostratigraphy (flow units) o Flow properties and heterogeneities of each unit  Discuss hydraulic conductivities and vertical gradients (refer to maps in 4. above)  Describe where flow units pinch out in each unit, as applicable  Discuss fractured bedrock heterogeneities across the site, including ranges of hydraulic conductivities and porosities  Discuss maximum depth of investigation and observed fracture density with depth; compare this to the depths of proximate supply wells Page 4 of 8  Areas of recharge and discharge  Flow directions o Potentiometric map (summer) of shallow/TZ unit o Potentiometric map (winter) of shallow/TZ unit o Potentiometric map (summer) of bedrock unit o Potentiometric map (winter) of bedrock unit  Potentiometric maps should utilize and show all facility wells, should clearly show all blue line tributaries, wetlands, and other SWs, and should indicate areas where a flow unit pinches out as applicable o Evaluation: Do seasonal or tidal influences effect GW flow or GW chemistry? 6. Background concentrations (PBTVs) of soil and groundwater.  Piper diagrams for shallow b/g, deep b/g, and bedrock b/g, along with well labels for plotted points  List PBTVs for soil  List PBTVs for groundwater, by flow unit  Methodology (appendix)  Description of background wells (why those chosen are appropriate for use) and soil sample locations (appendix)  Table of all raw background data showing strikethroughs of unused high pH, high turbidity, autocorrelated, and outlier data (appendix; digital excel file) 7. Contaminant assessment For each source area,  History of ash placement  Area, depth, and volume of ash (include also the area, depth, and volume of saturated/submerged ash)  Status of source removal or control  Orthophoto base map (large scale, 1 inch ~ 100 feet) showing waste boundary, compliance boundary if applicable, 2 to 4 ft topographic contours, all blue line surface water and wetland features, along with the following: o subset of supply well and SW receptors from 3. above that are potentially susceptible to contaminant migration from this particular source area  Include inset table with list of supply wells and SW receptors for this source area o monitor wells, supply wells, and SW, seep, ash, soil, and sediment locations  Indicate most recent value (ug/L) for boron and for each COI, and whether its concentration is increasing, decreasing, stable, or unknown  Evaluation: Show a vertical gradient isopleth map and discuss vertical gradients and their effect on GW flow  List COIs (constituents above 02L/IMAC/background) for each flow unit beyond compliance boundary (or that are within bedrock monitor wells within or beyond compliance boundary if receptors are potentially at risk)  List pH and Eh ranges found in: pore water, d/g shallow unit, d/g TZ unit, and d/g BR unit  Evaluation: Explain the geochemical controls on COIs that do not behave as a plume (Fe, Mn, etc.). Page 5 of 8  Evaluation: Use the pH, Eh, Kd, and HFO results to discuss the expected capacity of the subsurface to sorb cationic COIs and anionic COIs occurring from source to receptor within each of the flow units.  Provide the following “data inventory”: o (a) have background concentrations been formally established for all COIs in soil and groundwater? o (b) for each source area, how many wells within each flow system are located along the contaminant plume centerline? Along a cross sectional transect that is perpendicular to the plume centerline? o (c) how many wells in (b) above are screened across the most contaminated vertical interval of a given flow unit or are screened across the full thickness of the flow unit? o (d) is the d/g edge of the plume centerline measured or is this location obstructed by a major SW or other access issue? If so, is it measured by wells that are screened across each flow unit? o (d) what is the length of record and how many valid sample events are available for wells listed in (b), (c), and (d) above? o (e) does turbidity, well construction (for example, grout contamination, etc.), or well “break in” issues preclude the use of data in (b), (c), and (or) (d)? o (f) for each source area and within each flow unit, how many spatial locations were sampled for solid phase chemistry and were these locations associated with “end member” (maximum and minimum) groundwater concentrations for each contaminant[1]? How many of these spatial locations are associated with (b) or (c) above? o (g) given that iron hydroxide (HFO) content is a good indicator of retention capacity for most metal contaminants, how many locations in (f) was HFO measured?  For each COI in this particular source area, o Evaluation: Were wells properly positioned and screened to measure the horizontal and vertical extent of the plume? If so, describe the horizontal and vertical plume extent using plan view and cross sectional maps. o Has the plume migrated to any supply wells, SW receptors, or GW future use areas? o Has the plume migrated to any supply wells, SW receptors, or GW future use areas at concentrations above 2L/IMAC/background? o Evaluation: Were wells positioned and screened to measure the maximum concentrations migrating from source to receptor along the longitudinal plume centerline? If so, describe the plume characteristics is space and time as it flows along the centerline, through the identified flow units, and discharges into the nearest supply well or SW receptor. o Evaluation: Use maps, graphs, statistics, and mass movement or balance equations to show whether the plume is expanding and whether the plume is moving.  Show the COI-distance plot of wells positioned along a plume centerline from source to farthest d/g location (closest to receptor or future use area. [1] Measuring the solid phase contaminant concentrations in locations of both low and high groundwater COI concentrations are important in understanding the sorptive capacity of the system. This is particularly true in the case of non-linear isotherm adsorption models that describe most metals. That is, a soil has a limited ability to sorb contaminant mass due, for example, to limited sorption sites, so a soil can become less efficient at removing mass at higher dissolved concentrations. Page 6 of 8  If applicable, show COI-distance plots at different timepoints to demonstrate potential plume expansion or migration.  If applicable and sufficient sample events are available, use single-well linear regression or Mann-Kendall/Theil-Sen type trend statistics to show increasing or decreasing trends at selected d/g monitor wells. o Describe the soil-water pairs and Kd lab test sample results. Describe where they were collected, why those locations were selected, and whether those locations are reflective of high and low COI concentrations in a given flow unit. o Show concentration isopleths for each COI, including contours of concentrations below and well above the 2L/IMAC (choose ~ five contours per COI, from “moderately low” to “high”) o Show stacked boron-time plots of wells positioned along a plume centerline from source to farthest d/g location (closest to receptor)  Summary of corrective actions taken to date, if applicable  Describe preliminary corrective action alternatives for this source area 8. Flow model  Description of model  Model construction – domain, layers, boundary conditions, recharge and discharge areas, supply wells, hydraulic conductivities, stream conductances, etc. o Layer thicknesses in cross section (show vertical scale in feet) o Location of supply wells outside model domain  Calibration method o List of target wells used in calibration o List of monitor wells not used in calibration and the rationale for each that was omitted  Calibration results (where mapped, superimpose on orthophoto base map described above) o Hydraulic conductivity zones versus measured values for the zone o List of simulated versus observed heads (include wells and SW features) o List of simulated versus observed vertical gradients from well pair locations o List of simulated versus observed discharge to streams o Potentiometric surface  Simulated for each flow layer  Observed, shallow  Observed, deep  Observed, BR o Flow paths (particle tracks) from each source area o Reverse flow paths (particle tracks) from SW receptors o Reverse flow paths (particle tracks) from supply wells (because supply wells are usually open from casing (at ~50 to 75 ft) down to 200 to 500 feet, release particles in all simulated bedrock layers)  Quantitative sensitivity analyses to key inputs at various selected d/g locations  Describe the most significant model limitations 9. Transport model  Description of model  Model construction – boundary conditions, time steps, initial conditions, etc. o Source loading, per layer o Background concentrations, per layer Page 7 of 8 o Initial Kds, per layer o Dispersivities, per layer o Effective porosities, per layer  Calibration method o List of target wells used in calibration o List of monitor wells not used in calibration and the rationale for each that was omitted o Calibrated Kds, per layer  Calibration results (where mapped, superimpose on orthophoto base map described above) o List of simulated versus observed concentrations in target wells o List of simulated concentrations in SW discharge locations as shown using particle tracks released from source areas o List of simulated versus observed concentrations in selected well pair locations  Boron isopleth map  Simulated for each flow layer  Observed, shallow  Observed, deep  Observed, BR  For each source area, the time, direction, and distance of contaminant travel must be predicted under existing conditions and under any other contemplated source control measure (for example, engineered cap and (or) excavation). For these scenarios, the following figures are expected: o (a) a concentration-time plot for each COI corresponding to the following locations: (i) nearest supply well, (ii) nearest future groundwater use area, and (iii) nearest surface water.  In the plot margin, the following information should be provided: the time it takes for the COI to reach (i), (ii), and (iii), the time it takes for the COI to reach (i), (ii), and (iii) at its 2L/IMAC concentration, the time it takes for the COI to reach (i), (ii), and (iii) at its maximum concentration, and the time it takes for the COI to reach (i), (ii), and (iii) at a concentration that is back below the 2L/IMAC concentration. o (b) a map superimposed on the requested base map showing the maximum predicted migration distance, at any detectable concentration, of each COI. o (c) a map superimposed on the requested base map showing the maximum predicted migration distance, at the 2L/IMAC standard concentration, of each COI.  Quantitative sensitivity analyses to key inputs at various selected d/g locations and times  Describe the most significant model limitations 10. Geochemical model for COIs controlled primarily by geochemistry  Conceptual model based on observed site data o Describe geochemical controls on COI levels in each source area using site data o Assumptions used in developing the model o Discuss data used to develop the model  For example, how are mineral or adsorption concentrations in fractured media converted to PHREEQC concentrations representing reaction along the fractures?  How were modeled reactive mineral concentrations interpolated between or extrapolated from the limited number of data collected Page 8 of 8 o Discuss what the COI concentrations are most sensitive to (pH, Eh, iron/aluminum oxide content, Kd, distance from source, etc.) o Describe the most significant limitations of the model  Numerical model (PHREEQC or PHREEQC 1-D Transport model) o Description of model o Purpose of model o Model construction o Discuss data used to develop the flow model o Results with comparison to observed well data (PHREEQC model) or to longitudinal flow path transect data (PHREEQC 1-D Transport model) o Sensitivity analysis (to pH, Eh, Kd, COI concentration, total dissolved ion content, iron/aluminum oxide content, Kd, distance from source, etc.) o Describe the most significant limitations of the model 11. GW-SW mixing model  Description of model  Purpose of model  Model construction o Show on map the precise SW locations where model output (simulated SW concentration) was obtained o List and discuss data used to construct model  Permitted effluent discharge concentrations should be considered in the model construction o Assumptions  Results  Sensitivity analysis (to GW contaminant concentrations, permitted effluent concentrations, location where SW output was obtained, stream flow, nearby effluent loading to the SW, etc.)  Describe the most significant limitations of the model 2017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra Completed NCDEQ CSA Update Expectations Check List DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 1 of 13 NCDEQ provided extensive expectations to be included in the CSA Update, in addition to NORR (August 2014) guidance. The following is a guide to locate the requests in the CSA Update Report: DEQ Expectations Report Location 1. Site History Facility description, geographic setting, surrounding land use, permitting history, and compliance boundaries and permitted sampling, etc. Section 2 ash related history Section 2 history prior to Duke ownership Section 2.1 history of waste releases unrelated to coal ash Sections 2.4 & 2.7 2. Identification of Source Areas1 1Large ash basins or other waste areas may need to be divided into separate smaller source areas if, for example, contaminant transport is toward different sets of receptors. Where appropriate, some source areas may be strategically combined based on geographic proximity (for example, conjoining or overlapping source areas), common source characteristics and impacts, common receptors, and a shared proposed remedy. The Regional Office should be consulted when identifying source areas for purposes of CSA and CAP development. Sections 2.3, 2.4, and 3 3. Identification of Potential Receptors Duke to provide information on where new water lines are planned, estimated new water line taps, and projected location for filtration systems. Duke and DEQ will work together to provide most recent analytical analysis for inclusion in CSA. Appendix D & Section 4.0 Surface water : Is the SW used as drinking water supply? if so, what is the distance to intake? Sections 2.2, 4.0 & 4.5 Supply wells: Need map and table showing all receptors identified Figure 4-2 Has each identified supply well been abandoned and connected to alternative permanent water? Section 4, Appendix D Evaluation: Are COIs in supply wells above 2L/IMAC/background and sourced by ash? Section 14.3 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 2 of 13 DEQ Expectations Report Location 4. Raw Data Collected to Date Figures: • All GW monitoring and supply well locations Figure 2-11, Figure 2-12 & 4-1 Figure 4-2 • Show screened interval (ft. bgs.) and flow unit (use different color call out box for each flow unit) • Location, flow unit, and value of pH and Eh measurements • Most recent concentration of boron and COIs (ug/L) • Hydraulic conductivity (k) measurement value (ft/d) if available for corresponding well screen interval Figure 14-72 & Figure 14-75 • All SW, AOW seep and effluent channel (permitted) sample locations − Show most recent results of boron and COIs (ug/L) Figure 14-71 & Figure 14-74 • All solid phase sample locations, to include ash, soil, and sediment locations • Show sample depth (ft. bgs.) and flow unit • Concentration of COIs (mg/kg) • Location, depth (ft. bgs.) and flow unit of soil-water pairs shown as blue color font • Location, depth (ft. bgs.), flow unit for HFO measurements and value (mg/Kg) • Location, depth (ft. bgs.), flow unit for sorption coefficient (Kds) measurements and value (mL/g) Figure 14-70, & Figure 14-73 • Location of vertical gradient calculations between shallow/TZ unit and BR unit, showing value (+ is downward gradient, - is upward gradient) Figure 6-7 • Cross section maps showing ash position, hydrostratigraphy, screen/open intervals, water level, and Figures 6-1 to 6-4 • Groundwater boron and COI concentrations (ug/L) Figures 11-33 to 11-88 • Inset should show location (in plan view) of the cross section Figures 6-1 to 6- 4, & Figures 11- 33 to 11-88 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 3 of 13 DEQ Expectations Report Location Summary data tables: Solid Phase properties for ash, fill, alluvium, soil/saprolite, deep, and bedrock units, as applicable, including: − Porosity − Specific storage − Permeability (field, lab, historic) − Mineralogy and oxides − Physical Methodology, computations, etc. may be referenced, as applicable Tables 3-1, 3-2, 3-3, 3-4, 3-5, 6-1, 6-2, & 6-3 hydraulic conductivities (k, in ft/d), sorted by flow unit, along with well identifier, flow unit, and screened/open interval (ft bls) Tables 6-8 & 6-9 sorption coefficients (Kd), sorted by COI then flow unit, along with boring location identifier, flow unit, and depth (ft bls) Table 13-1 Appendices Raw data tables showing chemistry results for: • all GW, SW, and seep sample events (appendix and digital excel file) • all ash, soil, sediment, and whole rock chemistry results (appendix and digital excel file) • all SPLP samples (appendix and digital excel file) • lat/long, flow unit (if applicable), etc. should be included for each sample location • current “master spreadsheet” format may be used • lab QC data may be referenced if it has already been provided in a separate report Appendix B Summary table of monitor well construction details showing well, location (decimal degree lat/long), screen/open interval, depth to water, date installed, flow unit being monitored, date abandoned if applicable, etc. Table 2-1 • Water level measurements from all wells and current and historical measurement events (appendix and digital excel file) • List of wells that were dry during sampling or measurement attempts, along with its flow unit, screened/open interval, and date Table 6-5 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 4 of 13 DEQ Expectations Report Location Sorption coefficient testing - methodology, raw data, and computations may be referenced Appendix G • Boring logs and well construction records − Include all assessment, historic, CCR used for CAMA, or other wells installed to date − Each log should be quality controlled for accuracy and include static WL information. − Combined file Alpha-numeric sorting Appendix F Geophysical logs, rose diagrams, lineament map Figure 6-8 Soil and rock photos Section 6.1.2 Most recent pre-ash basin USGS topographic map, with superimposed source areas Figures 1-1 & 2-9 Screening level risk assessment − Human health Section 12.1 − Ecological Section 12.2 Flow and transport model Section 13.1 Geochemical model Section 13.2 GW-SW mixing model, if applicable Section 13.3 5. Site Conceptual Model Overview of the major components, including source(s), hydrologic boundaries, migration pathway(s), receptors, etc. Sections 4, 6, 12, 14 Regional geology and how it is affecting GW flow, GW quality, and contaminant transport at the site Section 5 & 14 Hydrostratigraphy (flow units) • Flow properties and heterogeneities of each unit Section 6.2.2 • Discuss hydraulic conductivities and vertical gradients (refer to maps in 4. above) Sections 6.5 & 6.4 • Describe where flow units pinch out in each unit, as applicable Figures 6-2 & 6-3 • Discuss fractured bedrock heterogeneities across the site, including ranges of hydraulic conductivities and porosities Sections 6.2.2, 6.5 & Table 6-1 & 6-8 • Discuss maximum depth of investigation and observed fracture density with depth; compare this to the depths of proximate supply wells Sections 11.1 & 14.3 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 5 of 13 DEQ Expectations Report Location • Areas of recharge and discharge (Include on vertical gradient isocon figure) Figure 6-7 & Section 6.4 • Flow directions − Potentiometric map (summer) of shallow/TZ unit − Potentiometric map (winter) of shallow/TZ unit − Potentiometric map (summer) of bedrock unit − Potentiometric map (winter) of bedrock unit Potentiometric maps should utilize and show all facility wells, should clearly show all blue line tributaries, wetlands, and other SWs, and should indicate areas where a flow unit pinches out as applicable Figure 6-5 & Figure 6-6 Evaluation: Do seasonal or tidal influences affect GW flow or GW chemistry? Section 14.1 6. Background concentrations (PBTVs) of soil and groundwater Piper diagrams for shallow b/g, deep b/g, and bedrock b/g, along with well labels for plotted points Figure 10-1 & Figure 10-2 List PBTVs for soil Table 7-1 List PBTVs for groundwater, by flow unit Table 10-1 Methodology (appendix) Appendix H Description of background wells (why those chosen are appropriate for use) and soil sample locations (appendix) Section 10.1 & Appendix H Table of all raw background data showing strikethroughs of unused high pH, high turbidity, autocorrelated, and outlier data (appendix; digital excel file) Table 10-1 & Appendix B DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 6 of 13 DEQ Expectations Report Location 7. Contaminant assessment For each source area History of ash placement Sections 2.1.1 & 2.1.2 Area, depth, and volume of ash (include also the area, depth, and volume of saturated/submerged ash) Sections 2.1.1, 2.1.2 & 3.3 Status of source removal or control Section 2.8 Orthophoto base map (large scale, 1 inch ~ 100 feet) showing waste boundary, compliance boundary if applicable, 2 to 4 ft topographic contours, all blue line surface water and wetland features, along with the following: Figures 2-11 & 2- 12 − subset of supply well and SW receptors from 3. above that are potentially susceptible to contaminant migration from this particular source area Figures 2-11, 2- 12, 4-1, & 4-2 − Include inset table with list of supply wells and SW receptors for this source area Figure 4-2 − monitor wells, supply wells, and SW, seep, ash, soil, and sediment locations Figures 2-11, 2- 12, 4-1, 4-2, 14- 70 to 14-75 − Indicate most recent value (ug/L) for boron and for each COI, and whether its concentration is increasing, decreasing, stable, or unknown Figures 14-43 to 14-69 Evaluation: Show a vertical gradient isopleth map and discuss vertical gradients and their effect on GW flow Figure 6-7, Section 14.1 List COIs (constituents above 02L/IMAC/background) for each flow unit beyond compliance boundary (or that are within bedrock monitor wells within or beyond compliance boundary if receptors are potentially at risk) Section 10.2 List pH and Eh ranges found in: pore water, d/g shallow unit, d/g TZ unit, and d/g BR unit Figures 14-72 & 14-75 Section 10.2 Evaluation: Explain the geochemical controls on COIs that do not behave as a plume (Fe, Mn, etc.). Sections 13.1 & 13.2 Evaluation: Use the pH, Eh, Kd, and HFO results to discuss the expected capacity of the subsurface to sorb cationic COIs and anionic COIs occurring from source to receptor within each of the flow units. Sections 13.1 & 13.2 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 7 of 13 DEQ Expectations Report Location Provide the following “data inventory” (a) have background concentrations been formally established for all COIs in soil and groundwater? Sections 7.1 and 10.1 (b) for each source area, how many wells within each flow system are located along the contaminant plume centerline? Along a cross sectional transect that is perpendicular to the plume centerline? Section 11.1.1 (c) how many wells in (b) above are screened across the most contaminated vertical interval of a given flow unit or are screened across the full thickness of the flow unit? Section 11.1 and Figures 11-33 to 11-88 (d) is the d/g edge of the plume centerline measured or is this location obstructed by a major SW or other access issue? If so, is it measured by wells that are screened across each flow unit? Section 11.1 and Figures 11-33 to 11-88 (d) what is the length of record and how many valid sample events are available for wells listed in (b), (c), and (d) above? Section 10.0 & Appendix B (e) does turbidity, well construction (for example, grout contamination, etc.), or well “break in” issues preclude the use of data in (b), (c), and (or) (d)? Section 10.0 & Appendix B (f) for each source area and within each flow unit, how many spatial locations were sampled for solid phase chemistry and were these locations associated with “end member” (maximum and minimum) groundwater concentrations for each contaminant[1]? How many of these spatial locations are associated with (b) or (c) above? [1] Measuring the solid phase contaminant concentrations in locations of both low and high groundwater COI concentrations are important in understanding the sorptive capacity of the system. This is particularly true in the case of non-linear isotherm adsorption models that describe most metals. That is, a soil has a limited ability to sorb contaminant mass due, for example, to limited sorption sites, so a soil can become less efficient at removing mass at higher dissolved concentrations. Sections 7 & 11, Figure 14-70 & 14-73 Section 11.2 (g) given that iron hydroxide (HFO) content is a good indicator of retention capacity for most metal contaminants, how many locations in (f) was HFO measured? Section 11.2, Figures 14-70 & 14-73 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 8 of 13 DEQ Expectations Report Location For each COI in this particular source area Evaluation: Were wells properly positioned and screened to measure the horizontal and vertical extent of the plume? If so, describe the horizontal and vertical plume extent using plan view and cross sectional maps. Section 11.1.1 Figures 11-33 to 11-88 Has the plume migrated to any supply wells, SW receptors, or GW future use areas? Sections 13.0 & 14.3 Has the plume migrated to any supply wells, SW receptors, or GW future use areas at concentrations above 2L/IMAC/background? Sections 13.0 & 14.3 Evaluation: Were wells positioned and screened to measure the maximum concentrations migrating from source to receptor along the longitudinal plume centerline? If so, describe the plume characteristics in space and time as it flows along the centerline, through the identified flow units, and discharges into the nearest supply well or SW receptor. Section 11.1 Evaluation: Use maps, graphs, statistics, and mass movement or balance equations to show whether the plume is expanding and whether the plume is moving. Sections 11.1, 14, & 15.2 Show the COI-distance plot of wells positioned along a plume centerline from source to farthest d/g location (closest to receptor or future use area. Figures 11-29 to 11-32 & 11-33 to 11-88 If applicable, show COI-distance plots at different timepoints to demonstrate potential plume expansion or migration. Figures 11-29 to 11-32 If applicable and sufficient sample events are available, use single-well linear regression or Mann-Kendall/Theil- Sen type trend statistics to show increasing or decreasing trends at selected d/g monitor wells. NA Describe the soil-water pairs and Kd lab test sample results. Describe where they were collected, why those locations were selected, and whether those locations are reflective of high and low COI concentrations in a given flow unit. Figures 14-70 & 14-73 Sections 6.7 & 13.1.2 DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 9 of 13 DEQ Expectations Report Location Show concentration isopleths for each COI, including contours of concentrations below and well above the 2L/IMAC (choose ~ five contours per COI, from “moderately low” to “high”) Figures 11-1 to 11-28 Show stacked boron-time plots of wells positioned along a plume centerline from source to farthest d/g location (closest to receptor) Figures 11-29 to 11-32 Summary of corrective actions taken to date, if applicable Section 2.8 Describe preliminary corrective action alternatives for this source area Section 15.4 8. Flow model • Description of model Section 13 (Summary) • Model construction – domain, layers, boundary conditions, recharge and discharge areas, supply wells, hydraulic conductivities, stream conductances, etc. − Layer thicknesses in cross section (show vertical scale in feet) − Location of supply wells outside model domain Section 13 (Summary) • Calibration method − List of target wells used in calibration − List of monitor wells not used in calibration and the rationale for each that was omitted To Be Provided in CAP • Calibration results (where mapped, superimpose on orthophoto base map described above) − Hydraulic conductivity zones versus measured values for the zone − List of simulated versus observed heads (include wells and SW features) − List of simulated versus observed vertical gradients from well pair locations − List of simulated versus observed discharge to streams − Potentiometric surface  Simulated for each flow layer  Observed, shallow To Be Provided in CAP DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 10 of 13 DEQ Expectations Report Location  Observed, deep  Observed, BR − Flow paths (particle tracks) from each source area − Reverse flow paths (particle tracks) from SW receptors − Reverse flow paths (particle tracks) from supply wells (because supply wells are usually open from casing (at ~50 to 75 ft) down to 200 to 500 feet, release particles in all simulated bedrock layers) • Quantitative sensitivity analyses to key inputs at various selected d/g locations To Be Provided in CAP • Describe the most significant model limitations To Be Provided in CAP 9. Transport model • Description of model Section 13.1 (Summary) • Model construction – boundary conditions, time steps, initial conditions, etc. − Source loading, per layer − Background concentrations, per layer − Initial Kds, per layer − Dispersivities, per layer − Effective porosities, per layer Section 13.1 (Summary) • Calibration method − List of target wells used in calibration − List of monitor wells not used in calibration and the rationale for each that was omitted − Calibrated Kds, per layer Section 13.1 (Summary) DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 11 of 13 DEQ Expectations Report Location • Calibration results (where mapped, superimpose on orthophoto base map described above) − List of simulated versus observed concentrations in target wells − List of simulated concentrations in SW discharge locations as shown using particle tracks released from source areas − List of simulated versus observed concentrations in selected well pair locations To Be Provided in CAP • Boron isopleth map − Simulated for each flow layer − Observed, shallow − Observed, deep − Observed, BR To Be Provided in CAP • For each source area, the time, direction, and distance of contaminant travel must be predicted under existing conditions and under any other contemplated source control measure (for example, engineered cap and (or) excavation). For these scenarios, the following figures are expected: − (a) a concentration-time plot for each COI corresponding to the following locations: (i) nearest supply well, (ii) nearest future groundwater use area, and (iii) nearest surface water.  In the plot margin, the following information should be provided: the time it takes for the COI to reach (i), (ii), and (iii), the time it takes for the COI to reach (i), (ii), and (iii) at its 2L/IMAC concentration, the time it takes for the COI to reach (i), (ii), and (iii) at its maximum concentration, and the time it takes for the COI to reach (i), (ii), and (iii) at a concentration that is back below the 2L/IMAC concentration. − (b) a map superimposed on the requested base map showing the maximum predicted migration distance, at any detectable concentration, of each COI. − (c) a map superimposed on the requested base map showing the maximum predicted migration distance, at the 2L/IMAC standard concentration, of each COI. To Be Provided in CAP DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 12 of 13 DEQ Expectations Report Location • Quantitative sensitivity analyses to key inputs at various selected d/g locations and times To Be Provided in CAP • Describe the most significant model limitations To Be Provided in CAP 10. Geochemical model for COIs controlled primarily by geochemistry • Conceptual model based on observed site data − Describe geochemical controls on COI levels in each source area using site data − Assumptions used in developing the model − Discuss data used to develop the model  For example, how are mineral or adsorption concentrations in fractured media converted to PHREEQC concentrations representing reaction along the fractures?  How were modeled reactive mineral concentrations interpolated between or extrapolated from the limited number of data collected − Discuss what the COI concentrations are most sensitive to (pH, Eh, iron/aluminum oxide content, Kd, distance from source, etc.) − Describe the most significant limitations of the model Section 13.2 (Summary) • Numerical model (PHREEQC or PHREEQC 1-D Transport model) − Description of model − Purpose of model − Model construction − Discuss data used to develop the flow model − Results with comparison to observed well data (PHREEQC model) or to longitudinal flow path transect data (PHREEQC 1-D Transport model) − Sensitivity analysis (to pH, Eh, Kd, COI concentration, total dissolved ion content, iron/aluminum oxide content, Kd, distance from source, etc.) − Describe the most significant limitations of the model To Be Provided in CAP DEQ CSA Update Expectations – Check List Roxboro Steam Electric Plant Duke Energy Progress, LLC Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 13 of 13 DEQ Expectations Report Location 11. GW-SW mixing model • Description of model Section 13.3 (Summary) • Purpose of model Section 13.3 (Summary) • Model construction − Show on map the precise SW locations where model output (simulated SW concentration) was obtained − List and discuss data used to construct model  Permitted effluent discharge concentrations should be considered in the model construction − Assumptions To Be Provided in CAP • Results To Be Provided in CAP • Sensitivity analysis (to GW contaminant concentrations, permitted effluent concentrations, location where SW output was obtained, stream flow, nearby effluent loading to the SW, etc.) To Be Provided in CAP • Describe the most significant limitations of the model To Be Provided in CAP 2017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra Zimmerman to Draovitch (September 1, 2017) 2017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra NCDEQ Background Dataset Review (July 7, 2017) 2017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra Revised Interim Monitoring Network (October 19, 2017) 2017 Comprehensive Site Assessment Update October 2017 Roxboro Steam Electric Plant SynTerra NCDENR NORR Letter (August 13, 2014)