NC0004987_Appx A - Regulatory Correspondence_20180129

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

APPENDIX A
REGULATORY CORRESPONDENCE

NCDEQ Expectations Document (July 18, 2017)
Completed NCDEQ CSA Update Expectations Check List
NCDENR NORR Letter (August 13, 2014)
NCDEQ Background Location Approvals
(October 11, 2017)
NCDEQ Background Dataset Review (July 7, 2017)
NCDEQ PBTV Approval Attachments (September 1, 2017)
NCDEQ Correspondence - Revised Interim Monitoring
Network (December 20, 2017)

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station 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

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

Completed NCDEQ CSA Update Expectations
Check List

2018 Comprehensive Site Assessment Update – Appendix A January 2018
Marshall Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 1 of 21
P:\Duke Energy Carolinas\18. MARSHALL\CSA Update January 2018\Appendices\FINAL_DEQ CSA Update Expectations - Check List_Marshall.docx

On July 21, 2017 NCDEQ provided additional requirements for the updated CSA reports. These new requirements
are in addition to those required by the NORR (August 2014). The following table provides the location of these
additional requirements in the CSA. Section numbering follows DEQ document.

DEQ EXPECTATIONS REPORT
LOCATION NOTES
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, & 3.0

2018 Comprehensive Site Assessment Update – Appendix A January 2018
Marshall Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 2 of 21
P:\Duke Energy Carolinas\18. MARSHALL\CSA Update January 2018\Appendices\FINAL_DEQ CSA Update Expectations - Check List_Marshall.docx

DEQ EXPECTATIONS REPORT
LOCATION NOTES
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
The City of Hickory already has a municipal line located
along Sherrills Ford Road; therefore the majority of the
households would require only service lines. Water line
extensions would be required along Mollys Backbone Road
(approximately 175 feet), Steamplant Road (approximately
500 feet), Gregory Road (approximately 650 feet), Marshall
Road (approximately 1700 feet), and Greenwood Road to
Clement Circle (approximately 1800 feet)
• Surface water:
o Is SW used as drinking water supply? If so, what is
the distance to intake? Section 4.4
Lake Norman is used as a water supply for Lincoln County
and the Town of Mooresville, 3.8 miles upstream of MSS.
Lincoln County treats raw water from Lake Norman at the
Lincoln County Water Treatment Facility located at 7674
Tree Farm Lane near Denver, NC, 5.6 miles downstream of
MSS.
Supply wells have not been abandoned, owners have been
contacted and offered alternative water supply.
• Supply wells:
o Need map and table showing all receptors identified
Figure 4-2
and 4-3
& Appendix D

o 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 4.3 &
14.3
Both the 2L standard and PBTV are exceeded for iron (MR-
4), manganese (MR-12 and MR-16), TDS (MR-37), and zinc
(MR-2). Plume distribution, among many lines of evidence,
indicates these concentrations are not sourced by ash.
2018 Comprehensive Site Assessment Update – Appendix A January 2018
Marshall Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 3 of 21
P:\Duke Energy Carolinas\18. MARSHALL\CSA Update January 2018\Appendices\FINAL_DEQ CSA Update Expectations - Check List_Marshall.docx

DEQ EXPECTATIONS REPORT
LOCATION NOTES
4. Raw Data Collected to Date
• Orthophoto base maps for:
o All GW monitoring and supply well Figures 2-4
& 4-3

- 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
Figures
11-121,
14-78

o All SW, AOW seep and effluent channel (permitted)
sample locations
- Show most recent results of boron and COIs
(ug/L)
- All SW locations sampled specifically to
determine whether contaminated GW is causing
2B violations
- Show most recent results of boron and COIs
(ug/L) using a bold font for exceedances
Figure 14-79

o 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)
o Location, depth (ft. bgs.) and flow unit of soil-water
pairs shown as blue color font
Figure 14-77

2018 Comprehensive Site Assessment Update – Appendix A January 2018
Marshall Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 4 of 21
P:\Duke Energy Carolinas\18. MARSHALL\CSA Update January 2018\Appendices\FINAL_DEQ CSA Update Expectations - Check List_Marshall.docx

DEQ EXPECTATIONS REPORT
LOCATION NOTES
o Location, depth (ft. bgs.), flow unit for HFO
measurements and value (mg/Kg)
o Location, depth (ft. bgs.), flow unit for sorption
coefficient (Kd) measurements and value (mL/g)
o Location of vertical gradient calculations between
shallow/TZ unit and BR unit, showing value
(+ is downward gradient, - is upward gradient)
Figure
11-121

o Location of vertical gradient calculations between
shallow/TZ unit and BR unit, showing value
(+ is downward gradient, - is upward gradient)
Figure 6-11
Table 6-11

• Cross section maps showing ash position,
hydrostratigraphy, screen/open intervals, water level, and
Figures
6-2 to 6-4

o Groundwater boron and COI concentrations (ug/L) Figures 11-64
to 11-120

o Inset should show location (in plan view) of the
cross section
• Summary data tables:
o 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 to
3-3, 6-1 to
6-8

2018 Comprehensive Site Assessment Update – Appendix A January 2018
Marshall Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 5 of 21
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
o Hydraulic conductivities (k, in ft/d), sorted by flow
unit, along with well identifier, flow unit, and
screened/open interval (ft bls)
Tables 6-12
& 6-13

o Sorption coefficients (Kd), sorted by COI then flow
unit, along with boring location identifier, flow unit,
and depth(ft bls)
Table 13-1

• 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
Appendix B

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.
Table 2-1

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
Table 6-9

2018 Comprehensive Site Assessment Update – Appendix A January 2018
Marshall Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red Page 6 of 21
P:\Duke Energy Carolinas\18. MARSHALL\CSA Update January 2018\Appendices\FINAL_DEQ CSA Update Expectations - Check List_Marshall.docx

DEQ EXPECTATIONS REPORT
LOCATION NOTES
o Sorption coefficient testing - methodology, raw
data, and computations may be referenced Appendix C
o 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

o Geophysical logs, rose diagrams, lineament map Figure 6-12
and 6-13

o Soil and rock photos Appendix G
o Most recent pre-ash basin USGS topographic map,
with superimposed source areas Figure 2-2
o Screening level risk assessment:
- Human health Section 12.1
- Ecological Section 12.2
o Flow and transport model Section 13.1
o Geochemical model Section 13.2
o 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 11,
14 & 15

• Regional geology and how it is affecting GW flow, GW
quality, and contaminant transport at the site
Section 5,
6 & 14

2018 Comprehensive Site Assessment Update – Appendix A January 2018
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• Hydrostratigraphy (flow units):
o Flow properties and heterogeneities of each unit Section 6.2
- Discuss hydraulic conductivities and vertical
gradients (refer to maps in 4. above) Section 6.5
& 6.6

- Describe where flow units pinch out in each unit,
as applicable Not
Applicable

- Discuss fractured bedrock heterogeneities
across the site, including ranges of hydraulic
conductivities and porosities Section 6.5

- Discuss maximum depth of investigation and
observed fracture density with depth; compare
this to the depths of proximate supply wells
Section 11.1
& 14.3
Maximum depth of investigation is 345 feet below
ground surface (AL-2BRLL). Fractured bedrock is
presumed the primary water supply source. While
not considered proximate (water supply wells
considered upgradient), the deepest reported water
supply well is 603 feet below ground surface.
• Areas of recharge and discharge (Include on vertical
gradient isoconcentration figure)
Figure 6-11
Section 6.2

• 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
Figures 6-6
to 6-11

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
o Evaluation: Do seasonal or tidal influences affect
GW flow or GW chemistry?
Section 11.2
Figures 14-1
through
14-38
Time series plots do not indicate significant seasonal
variation.
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
to 10-3
Piper diagrams for shallow, deep, and bedrock zones
included. The piper diagrams for the MSS provide
one line of evidence to describe differences in water
type between natural waters and pore water and
locations where mixing is likely.
• 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)
Appendix H

7. Contaminant assessment
For each source area:
• History of ash placement Section 2 and
3

• Area, depth, and volume of ash (include also the area,
depth, and volume of saturated/submerged ash) Section 3.3
• Status of source removal or control Section 2.8
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• 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 2-4

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

- Include inset table with list of supply wells and
SW receptors for this source area Figure 4-2
and 4-3

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
Figures 14-39
to 14-76

• Evaluation: Show a vertical gradient isopleth map and
discuss vertical gradients and their effect on GW flow

Figure 6-11,
Sections 6.2
and 14

• 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 10.3
& Section
11.1
Shallow – antimony, boron, chromium, cobalt, iron,
manganese, molybdenum, selenium, strontium, sulfate,
TDS, thallium
Deep – boron, cobalt, iron, manganese, strontium, sulfate,
TDS, vanadium
Bedrock – antimony, barium, boron, chromium, cobalt,
iron, manganese, molybdenum, strontium, TDS
• List pH and Eh ranges found in: pore water, d/g shallow
unit, d/g TZ unit, and d/g BR unit Figure 14-78
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• Evaluation: Explain the geochemical controls on COIs that
do not behave as a plume (Fe, Mn, etc.)
Sections 11.1
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 13.2

• Provide the following “data inventory”.
Items a through g are also included in CAP guidance
October 2017.
Section 11.1

o (a) have background concentrations been formally
established for all COIs in soil and groundwater?
Section 10.1
Tables 7-1
and 10-1
PBTV concentrations are proposed in the
Comprehensive Data Table (Appendix B) and the
Proposed Background Threshold Values for Naturally
Occurring Concentrations in Groundwater and Soil
(Appendix H).
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?
Table 11-1
Along plume centerline:
West Transect: 1 ash pore water, 3 shallow, 4 deep, 1
bedrock
Central Transect: 2 Ash Pore, 2 shallow, 3 deep, 3
bedrock, 1 Bedrock Lower
East: 3 shallow, 2 deep, 1 bedrock

Perpendicular:
West Transect: 2 ash pore water, 7 shallow, 8 deep, 1
bedrock.
Central Transect: 4 ash pore water, 5 shallow, 7 deep, 1
bedrock.
East Transect: 7 shallow, 6 deep, 2 bedrock
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
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?

Table 11-1

Using boron as a primary indicator constituent,
analytical results indicate the following zones along
transects are the most impacted:
West Transect - deep (4 wells)
Central Transect – shallow (2 wells)
East Transect – shallow (3 wells)

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
Table 11-1
Figure
11-121

The downgradient edge of the plume to the east of
the ash basin between the Dry Ash Landfill (Phase I)
is measured. The presence of Lake Norman
downgradient from the ash basin dam prevents
additional monitoring in that direction.

o (e) what is the length of record and how many valid
sample events are available for wells listed in (b),
(c), and (d) above?
Table 11-1

West Transect: 9 wells; 86 valid samples
(11/8/2007 – 9/26/2017)Perpendicular: 18 wells; 134 valid
samples (02/12/2008 – 09/26/2017)
Central Transect: 11 wells; 75 valid samples
(07/08/2015 – 09/287/2017)
Perpendicular: 18 wells; 165 valid samples ( 08/29/1989 –
09/26/2017)
East Transect: 6 wells; 37 valid samples (4/12/2016
– 09/28/2017)
Perpendicular: 15 wells; 182 valid samples (08/9/2000 -
10/02/2017)

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
o (f) 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)?

Table 11-1

Samples have occasionally been invalidated due to
turbidity issues. Wells are replaced if these
invalidations are chronic.

o (g) 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.

Table 11-1

Ash Basin: 164 solid phase samples; Ash = 64, Fill
= 11, Shallow = 49, Deep = 35, Bedrock = 5
Dry Ash Landfill (Phase I & II): 24 solid phase
samples; Ash = 12, Shallow = 0, Deep = 12,
Bedrock = 0
PV Structural Fill: 15 solid phase samples; Ash =
9, Shallow = 5, Deep = 1, Bedrock = 0

Yes, spatial locations include maximum and
minimum groundwater concentrations:
West Transect: 14 samples total, 5 Deep
Central Transect: 10 samples total, 2 Shallow
East Transect: 0 samples total

o (h) 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?
Table 11-1

West Transect: 2 samples total, 1 Deep
Central Transect: 5 samples total, 2 Deep
East Transect: 1 samples total, 0 Deep
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• 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.
Table 11-1
Wells are properly positioned to measure the
horizontal extent of the plume. Recently installed
wells AL-2BRLL and AB-1BRL are installed to define
the vertical extent. Currently limited data is
available at these locations. Continued monitoring
will determine if additional vertical assessment is
necessary. Additional monitoring wells within the
shallow flow system are likely needed to facilitate
effectiveness monitoring of selected groundwater
remedy.
o Has the plume migrated to any supply wells, SW
receptors, or GW future use areas?
Section 4.0 &
14

No
o Has the plume migrated to any supply wells, SW
receptors, or GW future use areas at concentrations
above 2L/IMAC/background?
Sections 4.0
& 14.3

No - water supply wells
Yes - Surface Water Receptors
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 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
Groundwater flow direction and analytical results do
not indicate migration of constituents sourced from
coal ash toward water supply well receptors.

Three transects (west, central, and east) have been
defined to facilitate the requested evaluation.
Discussion of plume characteristics from source to
surface water receptor along the flow transects is
included in Section 11.
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.

Section 11
Section 14

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
- Show the COI-distance plot of wells positioned
along aplume centerline from source to farthest
d/g location (closest to receptor or future use
area.)
Section 11
Section 14

- If applicable, show COI-distance plots at
different time points to demonstrate potential
plume expansion or migration.
Figures 14-1
through
14-38
Time series plots have been compiled in a matrix
format to demonstrate constituent occurrence
through time in relation to depth and distance from
source area to receptor.
- 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.
Figure
11-121
Section 13.2

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”)
Figures 11-1
to 11-57

o Show stacked boron-time plots of wells positioned
along a plume centerline from source to farthest
d/g location (closest to receptor)

Time series plots have been compiled in a matrix
format to demonstrate constituent occurrence
through time in relation to depth and distance from
source area to receptor.
• Summary of corrective actions taken to date, if applicable Section 2.8
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• Describe preliminary corrective action alternatives for this
source area
Sections
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 conductance, etc.
o Layer thicknesses in cross section (show vertical
scale in feet)
o Location of supply wells outside model domain

Section 13
(Summary)

• 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

Provided
in CAP

• 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
Provided
in CAP
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DEQ EXPECTATIONS REPORT
LOCATION NOTES
o Potentiometric surface
- Simulated for each flow layer
- Observed, shallow
- Observed, deep
- Observed, BR

Provided
in CAP
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)

Provided
in CAP
• Quantitative sensitivity analyses to key inputs at various
selected d/g locations

Provided
in CAP

• Describe the most significant model limitations Provided
in CAP

9. Transport model
• Description of model Section 13.1
(Summary)
• Model construction – boundary conditions, time steps,
initial conditions, etc.
o Source loading, per layer
o Background concentrations, per layer
o Initial Kd, per layer
o Dispersivity, per layer
o Effective porosity, per layer
Section 13.1
(Summary)

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• 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 Kd, per layer

Section 13.1
(Summary)

• 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
o Simulated for each flow layer
o Observed, shallow
o Observed, deep
o Observed, BR

Provided
in CAP

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• 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.

Provided
in CAP

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• Quantitative sensitivity analyses to key inputs at various
selected d/g locations and times
Provided
in CAP

• Describe the most significant model limitations Provided
in CAP

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

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
Section 13.2
(Summary)

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• 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
Provided
in CAP

11. GW-SW mixing model
• Description of model Section 13.3
(Summary)

• Purpose of model Section 13.3
(Summary)

• 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
Provided
in CAP

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DEQ EXPECTATIONS REPORT
LOCATION NOTES
• Results 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.)
Provided
in CAP

• Describe the most significant limitations of the model Provided
in CAP

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

NCDENR NORR Letter (August 13, 2014)

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

NCDEQ Background Location Approvals
(October 11, 2017)

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

NCDEQ Background Dataset Review (July 7, 2017)

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

NCDEQ PBTV Approval Attachments
(September 1, 2017)

2018 Comprehensive Site Assessment Update January 2018
Marshall Steam Station SynTerra

NCDEQ Correspondence - Revised Interim
Monitoring Network
(December 20, 2017)