NC0038377_Appx A - Regulatory Correspondence_20171101

2017 Comprehensive Site Assessment Update October 2017 
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APPENDIX A
REGULATORY CORRESPONDENCE
NCDEQ Expectations Document (July 18, 2017
Completed NCDEQ CSA Update Expectations Check List
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)
1981 C&D Landfill
2017 Comprehensive Site Assessment Update October 2017 
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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

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Completed NCDEQ CSA Update Expectations
Check List

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NCDEQ CSA Update Expectations – Check List

Page 1 of 13 
Tables – Shaded Blue       Figures – Shaded Green  CAP – Shaded Red 

NCDEQ provided expectations for elements to be included in the CSA Update, in 
addition to those provided in the NORR (August 2014) guidance.  This guide is 
provided to assist locating the requested elements in this CSA Update Report: 

NCDEQ Expectations Report Location
1. Site History
Facility description, geographic setting, surrounding
land use, permitting history, and compliance
boundaries and permitted sampling, etc.
Section 2.0
ash related history Section 2.0
history prior to Duke ownership Section 2.1
history of waste releases unrelated to coal ash Section 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 3.0
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 and
Section 4.0
Surface water :
Is the SW used as drinking water supply? if so, what is
the distance to intake?
Sections 4.0 and
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 4.0
Evaluation: Are COIs in supply wells above
2L/IMAC/background and sourced by ash? Section 14.3
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NCDEQ Expectations Report Location
4. Raw Data Collected to Date
Figures:
 All GW monitoring and supply well locations Figure 2-8 and
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 14-70
 All SW, AOW seep and effluent channel (permitted)
sample locations
 Show most recent results of boron and COIs
(ug/L)
Figure 14-71

 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 14-72

 Location of vertical gradient calculations between
shallow/TZ unit and BR unit, showing value (+ is
downward gradient, - is upward gradient)
Figure 6-12 and
Table 6-7

 Cross section maps showing ash position,
hydrostratigraphy, screen/open intervals, water
level, and
Figures 6-2 and
6-3

 Groundwater boron and COI concentrations (ug/L)

Figures 11-1
through 11-45
and Figures 11-
49 through 11-63
 Inset should show location (in plan view) of the
cross section
Figures 6-2, 6-3,
and 11-49
through 11-63
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NCDEQ 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, and 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 and 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 and
Appendix I
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

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NCDEQ Expectations Report Location
Sorption coefficient testing - methodology, raw data,
and computations may be referenced
Appendix C and
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 6-13
Soil and rock photos Section 6.0
Most recent pre-ash basin USGS topographic map, with
superimposed source areas
Figure 1-1 and
Figures 2-2
through 2-6
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 2.0, 3.0,
4,.0 6.0, 11.0,
12.0, and 14.0
Regional geology and how it is affecting GW flow, GW
quality, and contaminant transport at the site
Sections 5.0 and
14.0
Hydrostratigraphy (flow units)

 Flow properties and heterogeneities of each unit Section 6.2
 Discuss hydraulic conductivities and vertical
gradients (refer to maps in 4. above)
Sections 6.4 and
6.5
 Describe where flow units pinch out in each unit, as
applicable
Figures 6-2 and
6-3
 Discuss fractured bedrock heterogeneities across the
site, including ranges of hydraulic conductivities and
porosities
Section 6.0 and
Tables 6-1
through 6-9
 Discuss maximum depth of investigation and
observed fracture density with depth; compare this
to the depths of proximate supply wells
Sections 11.1 and
14.3
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NCDEQ Expectations Report Location
 Areas of recharge and discharge (Include on vertical
gradient isocon figure)
Figure 6-12 and
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
Figures 6-4
through 6-11
Evaluation: Do seasonal or tidal influences affect GW
flow or GW chemistry?
Sections 6.3 and
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
Figures 10-1
through 10-3
List PBTVs for soil Table 7-1 and
Appendix H
List PBTVs for groundwater, by flow unit Table 10-2 and
Appendix H
Methodology (appendix) Appendix H
Description of background wells (why those chosen are
appropriate for use) and soil sample locations
(appendix)
Section 10.1 and
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, and
Appendix H
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NCDEQ Expectations Report Location
7. Contaminant assessment
For each
source area:
History of ash placement Section 3.0
Area, depth, and volume of ash (include also the area,
depth, and volume of saturated/submerged ash)
Section 3.0
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:
Figure 2-8

 subset of supply well and SW receptors from 3.
above that are potentially susceptible to
contaminant migration from this particular source
area
Figures 2-8, 4-1,
4-2, and 4-3

 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 2-8, 4-1,
4-2, 14-70, 14-
71, and 14-72

 Indicate most recent value (ug/L) for boron and
for each COI, and whether its concentration is
increasing, decreasing, stable, or unknown
Figures 14-40
through 14-69
Evaluation: Show a vertical gradient isopleth map and
discuss vertical gradients and their effect on GW flow
Figure 6-12 and
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
Figure 14-70 and
Section 10.2
Evaluation: Explain the geochemical controls on COIs
that do not behave as a plume (Fe, Mn, etc.)
Sections 13.1 and
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 and
13.2
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NCDEQ 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 11.0
(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 11-49
through 11-63
(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?
Sections 11.1 and
14.0; Figures 11-
49 through 11-63
(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 and
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 7.0 and
11.0; Figure 14-
72

(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 and
Figure 14-72
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NCDEQ 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.
Sections 11.1 and
14.1; Figures 11-
49 through 11-63
Has the plume migrated to any supply wells, SW
receptors, or GW future use areas?
Sections 13.0 and
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 and
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,
13.1, 14.0, and
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 6-3; 11-
46 through 11-63
If applicable, show COI-distance plots at different
timepoints to demonstrate potential plume expansion or
migration.

Figures 11-46
through 11-48;
Section 13.1
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.
Sections 6.7 and
13.1; Figure 4-72
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
through 11-45
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NCDEQ Expectations Report Location
Show stacked boron-time plots of wells positioned along
a plume centerline from source to farthest d/g location
(closest to receptor)
Figures 11-46
through 11-48
Summary of corrective actions taken to date, if
applicable
Section 2.8
Describe preliminary corrective action alternatives for
this source area
Section 15.4
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 13.0
(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
 Observed, deep
To Be Provided in
CAP
2017 Comprehensive Site Assessment Update – Appendix A October 2017 
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NCDEQ Expectations Report Location
 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
 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)
 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
2017 Comprehensive Site Assessment Update – Appendix A October 2017 
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NCDEQ CSA Update Expectations – Check List

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NCDEQ Expectations Report Location
 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
 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
 Describe the most significant model limitations To Be Provided in
CAP
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NCDEQ CSA Update Expectations – Check List

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NCDEQ Expectations Report Location
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
 Numerical model (PHREEQC or PHREEQC 1-D
Transport model)
 Description of model
 Purpose of model
 Model construction
To Be Provided in
CAP
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NCDEQ CSA Update Expectations – Check List

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NCDEQ Expectations Report Location
 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
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 
Mayo Steam Electric Plant SynTerra 

Zimmerman To Draovitch
(September 1, 2017)

2017 Comprehensive Site Assessment Update October 2017 
Mayo Steam Electric Plant SynTerra 

NCDEQ Background Dataset Review
(July 7, 2017)
2017 Comprehensive Site Assessment Update October 2017 
Mayo Steam Electric Plant SynTerra 

Revised Interim Monitoring Plans for 14 Duke
Energy Facilities
(October 19, 2017)

2017 Comprehensive Site Assessment Update October 2017 
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NCDENR NORR Letter
(August 13, 2014)

2017 Comprehensive Site Assessment Update October 2017 
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1981 C&D Landfill