NC0004979_FINAL_Allen_CSA_Appendix_A_2018_20180130

2018 Comprehensive Site Assessment Update January 2018
Allen 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 (October 19, 2017)

2018 Comprehensive Site Assessment Update January 2018
Allen 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
Allen Steam Station SynTerra

Completed NCDEQ CSA Update Expectations
Check List

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

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 1 of 25

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.
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 2.3
• History prior to Duke ownership
Section 2.1
• History of waste releases unrelated to coal ash Section 2.4, Table
2-3

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

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

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 2 of 25

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

• Surface water :
Is the SW used as drinking water supply? if so, what is
the distance to intake?
Section 4.0 & 4.4 Lake Wylie is used as a water supply for the
City of Belmont. The water intake from the
lake is approximately four miles upstream
of the Allen Plant.
• Supply wells:
o Need map and table showing all receptors
identified
Figures 4-1 & 4-2

o Has each identified supply well been abandoned
and connected to alternative permanent water? Section 4.2
• Evaluation: Are COIs in supply wells above
2L/IMAC/background and sourced by ash?
Section 4.3, 14.2,
15.2

4. Raw Data Collected to Date
Figures:
• All GW monitoring and supply well locations
Figures 2-7, 2-8
4-1, & 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
Appendix B,
Figures 11-1
through 11-60,
11-74 through
11-157,
14-103 &
14-104

• All SW, AOW seep and effluent channel (permitted)
sample locations
Figures 2-8 & 14-
105

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

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 3 of 25

DEQ Expectations Report Location Notes
o Show most recent results of boron and COIs
(ug/L)
• 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)
Figures 7-1 & 14-
102

• Location of vertical gradient calculations between
shallow/TZ unit and BR unit, showing value (+ is
downward gradient, - is upward gradient)
Figures 6-13 to 6-
15

• Cross section maps showing ash position,
hydrostratigraphy, screen/open intervals, water
level, and
Figures 6-1 to 6-6

• Groundwater boron and COI concentrations (ug/L)

Figures 11-10 to
11-12 & 11-86 to
11-89, 14-103 &
14-104

• Inset should show location (in plan view) of the
cross section
Figures 6-1 to 6-6
& 11-74 to 11-
157

Summary data tables:
Solid Phase properties for ash, fill, alluvium,
soil/saprolite, deep, and bedrock units, as applicable,
including:
Tables 3-1, 3-2,
6-1 to 6-3, 6-5 to
6-8, & 6-16 to 6-
19

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

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 4 of 25

DEQ Expectations Report Location Notes
• Porosity
• Specific storage
• Permeability (field, lab, historic)
• Mineralogy and oxides
• Physical
Methodology, computations, etc. may be referenced, as
applicable
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 to 6-
15

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

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 5 of 25

DEQ Expectations Report Location Notes
• 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 6-9

Sorption coefficient testing - methodology, raw data,
and computations may be referenced
Appendix C
• Boring logs and well construction records o Include all assessment, historic, CCR used for
CAMA, or other wells installed to date o Each log should be quality controlled for accuracy
and include static WL information. o Combined file Alpha-numeric sorting
Appendix F
Geophysical logs, rose diagrams, lineament map Figures 6-16 & 6-
17

Soil and rock photos Appendix F
Most recent pre-ash basin USGS topographic map, with
superimposed source areas
Figure 2-2 & 2-3
Screening level risk assessment Section 12
o Human health Sections 12.1
&12.3

o Ecological Section 12.2
2018 Comprehensive Site Assessment Update – Appendix A January 2018
Allen Steam Station SynTerra

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 6 of 25

DEQ Expectations Report Location Notes
Flow and transport model Section 13.1
Geochemical model Section 13.2
GW-SW mixing model, if applicable
Section 11.2
CAP I Report Section 4.2:
Groundwater – surface water interaction
model did not identify potential impacts to
surface waters of Lake Wylie/Catawba
River. Additional surface water sampling is
anticipated to be completed, and an
evaluation of potential impacts of
groundwater on surface water will be
presented in the CAP
5. Site Conceptual Model
Overview of the major components, including source(s),
hydrologic boundaries, migration pathway(s), receptors,
etc.
Sections 3, 4, 6,
7, 11, 12, 14, 15

Regional geology and how it is affecting GW flow, GW
quality, and contaminant transport at the site
Section 5, 6, 14 &
15

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 &
6.5

• Describe where flow units pinch out in each unit, as
applicable
Figures 6-1 to 6-6

• Discuss fractured bedrock heterogeneities across the
site, including ranges of hydraulic conductivities and
porosities
Sections 6.2.2,
6.5, & Tables 6-
12 to 6-19

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

DEQ CSA Update Expectations – Check List

Key: Tables – Shaded Blue Figures – Shaded Green CAP – Shaded Red

Page 7 of 25

DEQ Expectations Report Location Notes
• Discuss maximum depth of investigation and
observed fracture density with depth; compare this
to the depths of proximate supply wells
Section 4.3, 11.1
& 14.3
Maximum depth of investigation is 260 feet
below ground surface (AB-22BRL).
While not considered proximate (water
supply wells considered upgradient), the
deepest reported water supply well is 900
feet below ground surface.
• Areas of recharge and discharge (Include on vertical
gradient isocon figure)
Figures 6-13 to 6-
15 & Section 6.3
and 6.4

• 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 6-7 to 6-
12

Evaluation: Do seasonal or tidal influences affect
GW flow or GW chemistry?

Sections 3.3.4,
6.3, 14.1 & 14.2
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
Sections 3.3, 9.3,
10.1 & 10.2
Figures 3-4, 9-1,
& 10-1 to 10-4
Piper diagrams for ash pore water, surface
water, AOWs, and shallow, deep, and
bedrock groundwater zones included. The
piper diagrams provide one line of evidence
to describe differences in water type
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Page 8 of 25

DEQ Expectations Report Location Notes
between natural waters and ash pore water
and locations where mixing is likely.
List PBTVs for soil

Table 7-1 Updated Proposed PBTVs presented in
Appendix H
List PBTVs for groundwater, by flow unit

Table 10-1 Updated Proposed PBTVs presented in
Appendix H
Methodology (appendix) Appendix C
Description of background wells (why those chosen are
appropriate for use) and soil sample locations
(appendix)
Sections 4.3, 7.1
& 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 B
7. Contaminant assessment
For each source area:
History of ash placement
Section 2.3 & 3.1
Area, depth, and volume of ash (include also the area,
depth, and volume of saturated/submerged ash)
Sections 2.3 &
3.3
Figures 6-1 to 6-6

Status of source removal or control Sections 2.3 &
2.8

Orthophoto base map (large scale, 1 inch ~ 100 feet)
showing waste boundary, compliance boundary if
applicable, 2 to 4 ft topographic contours, all blue line
surface water and wetland features, along with the
following:
Figures 2-1, 2-7,
2-8, 14-102 to
14-105

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DEQ Expectations Report Location Notes
o subset of supply well and SW receptors from 3.
above that are potentially susceptible to
contaminant migration from this particular source
area
Figures 2-1, 2-7,
4-1, 4-2, 14-103,
& 14-104

o Include inset table with list of supply wells and
SW receptors for this source area
Table 2-1, Figures
2-7, 2-8, 14-103,
& 14-104

o monitor wells, supply wells, and SW, seep, ash,
soil, and sediment locations
Figures 2-7, 2-8,
4-1, 4-2

o Indicate most recent value (ug/L) for boron and
for each COI, and whether its concentration is
increasing, decreasing, stable, or unknown
14-81 to 14-101
Evaluation: Show a vertical gradient isopleth map
and discuss vertical gradients and their effect on
GW flow
Figures 6-13 to 6-
15, Sections,
10.2, 11.1, 14.1,
& 14.2

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 4.3, 10.2,
10.3, 11.1, 14.1,
& 14.2

Figures 11-1 to
11-60
Bedrock COI exceedances within
Compliance Boundary (most recent
sampling event) – 15 valid samples (most
recent sampling event)
2L/IMAC: Boron (3), Chromium (1), Cobalt
(2), Iron (2), Manganese (8), Vanadium
(15)
PBTV: pH (2), Boron (5), Chloride (15),
Strontium (12), Sulfate (15), TDS (8),
Antimony (2), Arsenic (7), Barium (9),
Cadmium (1), Chromium VI (3), Chromium
(3), Cobalt (5), Iron (3), Manganese (9),
Molybdenum (4), Nickel (4), Selenium (1),
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DEQ Expectations Report Location Notes
Vanadium (2), Radium (Total) (2), Uranium
(Total) (5)

COI exceedances Outside Compliance
Boundary (most recent sampling
event):

2L/IMAC:
Shallow (5 valid samples): Iron (1),
Vanadium (5)
Deep (6 valid samples): Iron (2),
Manganese (1), Vanadium (5)
Bedrock (5 valid samples): TDS (1),
Antimony (1), Barium (1), Chromium (VI)
(1), Chromium (1), Iron (1), Manganese
(1), Vanadium (5)

PBTV:
Shallow (5 valid samples): Strontium (1),
Sulfate (1), TDS (1), Arsenic (1), Chromium
(1), Nickel (1), Selenium (2), Vanadium (1)
Deep (6 valid samples): Strontium (1), TDS
(1), Barium (1), Manganese (1), Vanadium
(2), Radium (Total) (3)
Bedrock (5 valid samples): pH (2), Chloride
(4), Strontium (3), Sulfate (3), TDS (2),
Antimony (1), Arsenic (3), Barium (1),
Chromium (VI) (2), Chromium (2), Cobalt
(1), Iron (1), Manganese (1), Molybdenum
(3), Nickel (1), Selenium (1), Vanadium
(1), Uranium (Total) (2)

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Page 11 of 25

DEQ Expectations Report Location Notes
List pH and Eh ranges found in: pore water, d/g shallow
unit, d/g TZ unit, and d/g BR unit

Section 10.2,
Figure 14-103

Evaluation: Explain the geochemical controls on
COIs that do not behave as a plume (Fe, Mn, etc.).
Sections 13.2 &
11.1.2
To Be Provided in
CAP

Additional discussion to be provided in the
geochemical model in the CAP.
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.

Section 13.2
To Be Provided in
CAP
Additional discussion to be provided in the
geochemical model in the CAP.
Provide the following “data inventory”:

(a) have background concentrations been formally
established for all COIs in soil and groundwater?

Sections 4.3, 7 &
10,
Table 11-1

PBTVs have been proposed and partially
approved as discussed in Section 7 and 10.
Updated proposed PBTVs are also presented
in Appendix H.

(b) for each source area, how many wells within each
flow system are located along the contaminant plume
centerline? Along a cross sectional transect that is
perpendicular to the plume centerline?
Section 11.1 &
13,
Table 11-1
Figure 11-159
Parallel to transect/centerline of flow:
Ash Storage Area/ Coal Pile Transect: 2 ash
pore, 3 shallow, 5 deep, 2 bedrock
Inactive Ash Basins Transect: 3 ash pore, 4
shallow, 7 deep, 2 bedrock
Active Ash Basin – North Transect: 4 ash
pore, 3 shallow, 4 deep, 1 bedrock upper,
and 3 bedrock
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DEQ Expectations Report Location Notes
Active Ash Basin – South Transect: 3 ash
pore, 3 shallow, 5 deep, 3 bedrock, 2
bedrock-lower

Perpendicular to transect/centerline of
flow:
Ash Storage Area/ Coal Pile Transect: 7 ash
pore and 7 deep
Inactive Ash Basins Transect: 3 ash pore, 4
shallow, 6 deep, and 1 bedrock
Active Ash Basin – North Transect: 3 ash
pore, 3 shallow, 5 deep, 1 bedrock- upper,
1 bedrock
Active Ash Basin – South Transect: 8
shallow and 6 deep
(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 & 13.2
Figures 11-74 to
11-157, & 11-159
Table 11-1
Parallel to transect/centerline of flow:
Ash Storage Area/ Coal Pile Transect: 3
shallow
Inactive Ash Basins Transect: 4 shallow
Active Ash Basin – North Transect: 3
shallow
Active Ash Basin – South Transect: 3
bedrock and 2 bedrock-lower

*No wells are screened across the full
thickness of an aquifer or it is indeterminate
based on available information

Perpendicular to transect/centerline of
flow:
A Ash Storage Area/ Coal Pile Transect: 7
shallow
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DEQ Expectations Report Location Notes
Inactive Ash Basins Transect: 4 shallow
Active Ash Basin – North Transect: 3
shallow
Active Ash Basin – South Transect: 0
bedrock

*No wells are screened across the full
thickness of an aquifer or it is indeterminate
based on available information
(d) is the d/g edge of the plume centerline measured or
is this location obstructed by a major SW or other
access issue? If so, is it measured by wells that are
screened across each flow unit?
Section 11,
Figures 11-74 to
11-157, & 11-159
Table 11-1
Downgradient edge of the plume is
measured near, and obstructed by,
Lake Wylie (Catawba River).

Downgradient edge of plume centerline
is characterized by:
Active Ash Basin - South Transect: AB-10S,
AB-10D
Active Ash Basin - North Transect: GWA-3S,
GWA-3D, GWA-3BR, GWA-3BRA
Inactive Ash Basin Transect: GWA-4S,
GWA-4D, GWA-4BR
Ash Storage Area/Coal Pile Transect: N/A
(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,
Table 11-1,
Figure 11-159
Parallel to transect/centerline of flow:
Active Ash Basin - South Transect:
7/7/2011-11/10/2017
Active Ash Basin – North Transect:
7/7/2011-9/15/2017
Inactive Ash Basin Transect: 6/17/2015-
9/13/2017
Ash Storage Area/Coal Pile Transect:
6/16/2015-11/10/2017

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DEQ Expectations Report Location Notes
Perpendicular to transect/centerline of
flow:
Active Ash Basin - South Transect:
11/16/2005-9/13/2017
Active Ash Basin - North Transect:
5/8/2006-9/15/2017
Inactive Ash Basin Transect: 7/7/2011-
9/18/2017
Ash Storage Area/Coal Pile Transect:
6/16/2015-9/14/2017
(e) does turbidity, well construction (for example, grout
contamination, etc.), or well “break in” issues preclude
the use of data in (b), (c), and (or) (d)?
Section 10.0,
Appendix B,
Table 11-1,
Figure 11-159
Parallel to transect/centerline of flow:
Active Ash Basin - South Transect: 65
samples omitted
Active Ash Basin - North Transect: 91
samples omitted
Inactive Ash Basin Transect: 43 samples
omitted
Ash Storage Area/ Coal Pile Transect: 31
samples omitted
Perpendicular to transect/centerline of
flow:
Active Ash Basin - South Transect: 32
samples omitted
Active Ash Basin - North Transect: 43
samples omitted
Inactive Ash Basin Transect: 50 samples
omitted
Ash Storage Area/ Coal Pile Transect: 22
samples omitted
(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
Sections 7, 11.2
Table 11-1
Figures 11-159,
Active Ash Basin: 68 solid phase samples;
Ash = 29, Shallow = 37, Deep = 0, Bedrock
= 2
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DEQ Expectations Report Location Notes
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.
14-103 & 14-104

Inactive Ash Basin: 92 solid phase
samples; Ash = 50, Shallow = 40, Deep =
0, Bedrock = 2

Not all spatial locations include maximum
and minimum groundwater concentrations.

Parallel to transect/centerline of flow:
Active Ash Basin - South Transect: 18
samples total, 1 bedrock
Active Ash Basin - North Transect: 19
samples total, 11 shallow
Inactive Ash Basin Transect: 30 samples
total, 24 shallow
Ash Storage Area/Coal Pile Transect: 16
samples total, 11 shallow

Perpendicular to transect/centerline of
flow:
Active Ash Basin - South Transect: 0
samples, 0 bedrock
Active Ash Basin - North Transect: 13
samples total, 9 shallow
Inactive Ash Basin Transect: 18 samples
total, 12 shallow
Ash Storage Area/Coal Pile Transect: 8
samples total, 6 shallow

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DEQ Expectations Report Location Notes
(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,
Table 11-1,
Figure 11-159
Parallel to transect/centerline of flow:
Active Ash Basin - South Transect: 3
samples total, 0 bedrock
Active Ash Basin - North Transect: 1
samples total, 0 shallow
Inactive Ash Basin Transect: 4 samples
total, 3 shallow
Ash Storage Area/Coal Pile Transect: 1
samples total, 1 shallow

Perpendicular to transect/centerline of
flow:
Active Ash Basin - South Transect: 0
samples total, 0 bedrock
Active Ash Basin - North Transect: 2
samples total, 2 shallow
Inactive Ash Basin Transect: 2 samples
total, 2 shallow
Ash Storage Area/Coal Pile Transect: 1
samples total, 1 shallow

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 10.2,
10.3, 11.1, 11.2,
14 & 15.2
Figures 11-1 to
11-60 & 11-74 to
11-157

Wells are properly positioned to measure
the horizontal extent of the plume. Recently
installed well AB-22BRL was installed to
define the vertical extent downgradient of
the active ash basin. Currently limited data
is available at this location. Continued
monitoring will determine if additional
vertical assessment is necessary. Additional
monitoring wells within the shallow flow
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DEQ Expectations Report Location Notes
system beneath the ash basins and vertical
extent downgradient of the ash basins are
likely needed to facilitate effectiveness
monitoring of selected groundwater.
Has the plume migrated to any supply wells, SW
receptors, or GW future use areas?
Sections 4.3, 10,
11, 13.1, 14.1, &
15.2
No - water supply wells
Yes - Surface Water Receptors
Has the plume migrated to any supply wells, SW
receptors, or GW future use areas at concentrations
above 2L/IMAC/background?
Sections 4.3, 10,
11, 13.1, 14.1, &
15.2
No - water supply wells
Yes - Surface Water Receptors
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 10, 11.1,
14.1, 15.1, 15.2

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.
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, 13.1,
14, & 15
Figures 11-61 to
11-73 and 14-81
to 14-101

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DEQ Expectations Report Location Notes
Show the COI-distance plot of wells positioned along a
plume centerline from source to farthest d/g location
(closest to receptor or future use area.
Figures 11-61 to
11-73

If applicable, show COI-distance plots at different time
points to demonstrate potential plume expansion or
migration.

Figures 14-1
through 14-80
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.
N/A
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 11 &
13.2
Figure 11-159

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
11-60

Show stacked boron-time plots of wells positioned along
a plume centerline from source to farthest d/g location
(closest to receptor)
Figures 14-13 to
14-16
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.
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DEQ Expectations Report Location Notes
Summary of corrective actions taken to date, if
applicable
Section 2.3, 2.8,
4.2, & 15.4

Describe preliminary corrective action alternatives for
this source area
Section 15.4
8. Flow model
• Description of model Section 13

• Model construction – domain, layers, boundary
conditions, recharge and discharge areas, supply
wells, hydraulic conductivities, stream
conductance’s, etc.
o Layer thicknesses in cross section (show vertical
scale in feet)
o Location of supply wells outside model domain

Section 13.1
• 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

To Be Provided in
CAP

• Calibration results (where mapped, superimpose on
orthophoto base map described above)
o Hydraulic conductivity zones versus measured
values for the zone

To Be Provided in
CAP

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DEQ Expectations Report Location Notes
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

To Be Provided in
CAP

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DEQ Expectations Report Location Notes
• Describe the most significant model limitations To Be Provided in
CAP

9. Transport model
• Description of model

Section 13.0 &
13.1

• Model construction – boundary conditions, time
steps, initial conditions, etc. o Source loading, per layer o Background concentrations, per layer o Initial Kds, per layer o Dispersivities, per layer o Effective porosities, per layer
Section 13.1
• 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
Section 13.1
• 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
To Be Provided in
CAP

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DEQ Expectations Report Location Notes
• Boron isopleth map o Simulated for each flow layer o Observed, shallow o Observed, deep o 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: 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.

To Be Provided in
CAP

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DEQ Expectations Report Location Notes
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
To Be Provided in
CAP

• Describe the most significant model limitations To Be Provided in
CAP

10. Geochemical model for COIs controlled primarily by geochemistry
• Conceptual model based on observed site data
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

Section 13.2

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DEQ Expectations Report Location Notes
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

To Be Provided in
CAP

11. GW-SW mixing model
• Description of model To Be Provided in
CAP

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DEQ Expectations Report Location Notes
• Purpose of model To Be Provided in
CAP

• 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
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

2018 Comprehensive Site Assessment Update January 2018
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NCDENR NORR Letter (August 13, 2014)

2018 Comprehensive Site Assessment Update January 2018
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NCDEQ Background Location Approvals
(October 11, 2017)

2018 Comprehensive Site Assessment Update January 2018
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NCDEQ Background Dataset Review (July 7, 2017)

2018 Comprehensive Site Assessment Update January 2018
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NCDEQ PBTV Approval Attachments
(September 1, 2017)

2018 Comprehensive Site Assessment Update January 2018
Allen Steam Station SynTerra

NCDEQ Correspondence - Revised Interim
Monitoring Network
(October 19, 2017)