2016-05-13 GHI Belews Creek Report- Final

GEO—HYDRO, INC 1928 E.141hAvenue
Denver, Colorado 80206
Consulting in Geology and Hydrogeology [phone]
EXPERT REPORT OF
MARK A. HUTSON, PG
Belews Creek Steam Station Ash Basin
Belews Creek, NC
Prepared for:
Southern Environmental Law Center
601 West Rosemary Street
Suite 220
Chapel Hill, NC 27516-2356
May 2016

GEO-HYDRO, INC
1. Summary of Opinions Formed
Based upon my review of the available information I have formed the following opinions on closure
of the coal ash basin at the Belews Creek Steam Station (BCSS).
1. Coal ash stored in the Belews Creek ash basin is a source of contamination detected in
surface water and groundwater resources.
2. Capping the waste within the footprint of the Belews Creek ash basin will not be protective
of groundwater quality within or downgradient of the basin.
3. The Groundwater Flow and Transport Model does not reflect real-world conditions
4. Monitored Natural Attenuation (MNA) is not a viable remedial option for impacted
groundwater and surface water downgradient of the Belews Creek ash basin.
5. Excavation of the coal ash will reduce the concentration and extent of groundwater
contaminants.
6. The coal combustion residual impoundment risk classification proposed by North Carolina
Department of Environmental Quality (NCDEQ) improperly minimizes protection of
environmental quality.
The background and rationale behind each of these opinions are described in this report.

GEO-HYDRO, INC
2. Introduction
Duke Energy (Duke) currently stores coal ash in a 292 -acre, unlined, lagoon at the BCSS in Stokes
County NC. Pollution caused by the coal ash at this site is currently the subject of an enforcement
action brought by the NCDEQ to enforce clean water laws in North Carolina. Organizations
represented by the Southern Environmental Law Center are also parties to this litigation.
North Carolina General Assembly Session Law 2014-122, the Coal Ash Management Act (CAMA)
of 2014, required the owner of coal combustion waste surface impoundments to conduct
groundwater monitoring, assessment and remedial activities at coal ash basins across the state, as
necessary. The owners of coal ash surface impoundments were required to submit a Groundwater
Assessment Plan (GAP) to NCDEQ by December 31, 2014. Comprehensive Site Assessment (CSA)
reports that reported the results of site characterization activities were required to be submitted
within 180 days of approval of the GAP. Information developed under the CSA provided the data to
be used to prepare Corrective Action Plans (CAP) that were to be submitted to NCDEQ within 90
days of submittal of the CSA. An agreement between Duke and NCDEQ resulted in breaking the
CAP into Parts 1 and 2.
Further, CAMA specifies that any impoundments classified by NCDEQ as high-risk be closed no
later than December 31, 2019 by dewatering the waste and either, a) excavating the ash and
converting the impoundment to an industrial landfill, or b) excavating and transporting the waste off-
site for disposal in an appropriately licensed landfill. Intermediate -risk impoundments are required
to be closed similarly to high-risk impoundments, but under a relaxed closure deadline of December
31, 2024. Impoundments classified as low-risk by NCDEQ must be closed by December 31, 2029
either similarly to the high and intermediate -risk sites, or by dewatering to the extent practicable and
capping the waste in place.
In January 2016 the NCDEQ issued Draft Proposed Risk Classifications (NCDEQ, 2016) for 10 ash
impoundment sites, including BCSS. The draft proposed risk classification assigned to BCSS is low
to intermediate risk pending clarification of uncertainty related to potential impacts to side -gradient
well users. Low risk ratings allow for closure of the impoundment by capping waste in place. On
behalf of the Southern Environmental Law Center, I have reviewed the CSA (HDR, 2015a), the CAP
Part 1 (HDR, 2015b), the CAP Part 2 (HDR, 2015c), and the Draft Proposed Risk Classifications
(NCDEQ, 2016).
This report details my opinions regarding: the source of groundwater and surface water pollution at
BCSS, potential remedies for that pollution discussed in the Corrective Action Plans, and the
proposed risk classification for the BCSS site.
2

GEO-HYDRO, INC
3. Qualifications
The opinions expressed in this document have been formulated based upon my formal education in
geology and over thirty-five years of experience on a wide range of environmental characterization
and remediation sites. My education includes B.S. and M.S. degrees in geology from Northern
Illinois University and the University of Illinois at Chicago, respectively. I am a registered
Professional Geologist (PG) in Kansas, Nebraska, Indiana, and Wisconsin, a Certified Professional
Geologist by the American Institute of Professional Geologists, and am currently serving as Past
President of the Colorado Ground Water Association.
My entire professional career has been focused on regulatory, site -characterization, and remediation
issues related to waste handling and disposal practices and facilities. I have worked on contaminated
sites in over 35 states and the Caribbean. My site characterization and remediation experience
includes activities at sites located in a full range of geologic conditions, involving soil and
groundwater contamination in both unconsolidated and consolidated geologic media, and a wide
range of contaminants. I have served in various technical and managerial roles in conducting all
aspects of site characterization and remediation including definition of the nature and extent of
contamination, directing human health and ecological risk assessments, conducting feasibility
studies for selection of appropriate remedies to meet remediation goals, and implementing remedial
strategies. For the last ten years much of my consulting activity has been related to groundwater
contamination and permitting issues at coal ash storage and disposal sites.

GEO-HYDRO, INC
4. Site Summary
Site Setting
The BCSS plant is a coal-fired electricity -generating facility located in north -central North Carolina in
the northeastern corner of Stokes County, North Carolina. The northern plant property line extends to
the North Carolina/Virginia state line. Belews Lake borders the ash basin to the east and the Dan
River is located to the north and northwest. The BCSS plant began coal-fired power production in
1974.
The 292 acre BCSS ash basin was formed by construction of a dam across the upper reaches of Little
Belews Creek', a tributary to the Dan River, that once flowed in the valley immediately northwest of
the BCSS (Figure 1). The basin is impounded by an earthen dam approximately 2,000 feet long, with
a dam height of 140 feet, and a crest height elevation of 770 feet above mean sea level (msl). The full
pond capacity of the ash basin was estimated to be 17,656,000 cubic yardsz. Coal ash and ash -
impacted water have buried the stream behind the dam. The BCSS ash basin receives a combination of
waste streams including flows from the ash removal system, BCSS powerhouse and yard holding
sumps, chemical holding pond, coal yard sumps, stormwater, landfill leachate, and treated flue gas
desulfurization (FGD) wastewater.
Nature and Extent of Groundwater Impacts
The CSA determined that leaching from waste impounded within the ash basins impacts groundwater
in the vicinity of the ash basin 3. Sources of ash -related contaminants other than the ash basin include
the Pine Hall Road Ash Landfill and an Ash Structural Fill area, although neither of these sources were
fully evaluated as part of this investigation. Constituents of Interest (COIs) in groundwater at the
BCSS site include antimony, arsenic, beryllium, boron, cadmium, chloride, chromium, hexavalent
chromium, cobalt, iron, manganese, pH, selenium, sulfate, thallium, total dissolved solids (TDS), and
vanadium4. Areas of the site where groundwater sampling data has been interpreted by Duke to have
source -related exceedances of groundwater quality standards are indicated on Figure 2.
The CSA described three hydrogeologic units or flow layers referred to as the shallow, deep
(transition) and bedrock layers. The zone closest to the surface is the shallow or surficial flow zone
encompassing saturated conditions, where present, in the residual soil or saprolite beneath the site. A
transition zone is encountered below the surficial zone and the bedrock is characterized primarily by
partially weathered rock of variable thickness. The bedrock flow zone occurs below the transition
1 HDR 2015a, p. 9
2 HDR, 2015a, p.16
3 HDR, 2015a, p. 117
4 HDR, 2015c, p.22
2

GEO-HYDRO, INC
zone and is characterized by the storage and transmission of groundwater in water -bearing fractures.
Figures included in the groundwater modeling reports indicate that under current conditions, elevated
concentration of COIs are found in all three flow layers (shallow, deep and bedrock) beneath the ash
basin. A full understanding of the extent of contamination in each flow zone was not achieved because
an insufficient number of monitoring wells were installed during the investigation to identify the
leading edge of contaminant plumes.
Ash -impacted water exits the impoundment to the north by seeping through and around the dam and
discharging to the surface into Little Belews Creek and subsequently into the Dan River, and by
migrating downgradient from the ash basin toward adjacent drainages. Examination of Figure 2 shows
that all of the monitoring wells located north of the dam lie within the area of exceedance of applicable
groundwater standards. There are no monitoring wells located further downgradient between the area
of exceedance and the Dan River, so the extent of groundwater contamination toward the north has not
been identified.
Groundwater flow on the east side of the ash basin is poorly defined, but clearly shows areas of flow
from the impoundment toward Belews Lake. Water elevation within the ash basin (Figure 3) at
monitoring location AB -71) was 759.63 feet above mean sea level (msl). The monitoring point east of
AB -71), and toward Belews Lake, is well GWA-61) which shows a water elevation of 753.39, a drop in
water elevation of 6.24 feet. Figure 2 shows that Duke has interpreted all monitoring wells located on
the east and southeast portions of the ash basin to be within the area of exceedance of applicable
groundwater standards. Additionally, monitoring wells GWA-3S and GWA-31) off the northeast
corner of the impoundment are interpreted on Figure 2 to be impacted. This information indicates that
groundwater is currently flowing from the ash basin toward the east, and that the extent of ash -related
contaminants in groundwater east and southeast of the ash basin has not been adequately defined.
Additional monitoring locations in the area east of the ash basin would likely be necessary to
adequately describe flow and the extent of contaminants in groundwater east of the ash basin and
discharging into Belews Lake.
The deep zone potentiometric surface map (Figure 3) shows a groundwater divide to the south of the
impoundment with flow indicated to be northward toward the impoundment, southward toward Belews
Creek, and eastward toward Belews Lake. Monitoring wells GWA-12S, GWA-1213R, and GWA-12D
are interpreted by Duke to be located in an area of exceedance (Figure 2) south of the groundwater
divide. These wells are located just west of the area of Area Of Wetness (AOW) sample location S-9
which showed high concentrations of ash -related parameters when sampled during the site assessment.
Duke maintained in the CSA6 that the seep at location S-9 was unrelated to the ash basin, even though
the seep water "has a geochemical make-up similar to ash basin porewater and ash basin surface
'HDR, 2015b
6 HDR, 2015a, p. 87
5

GEO-HYDRO, INC
water." The head difference between the ash basin and S-9, and the similarity of ash basin pore water
chemistry to that found at location S-9 indicates that flow from the basin through fractures or other
preferential flow pathways is the likely source of ash -impacted water on the south side of the inferred
groundwater divide. Additional investigation activities commenced in March 2016 to delineate the
horizontal extent of impacted groundwater and refine understanding of hydrogeologic properties in this
area.
Ash—impacted groundwater is also migrating to the west from the ash basin, beneath the topographic
divide, and into the adjoining drainage. The CSA described Seeps S-2 and S-4 as follows:
"West of Middleton Loop Road and the ash basin dam on Duke Energy property are Seeps S-2
and S-4, and sampling reported elevated levels of TDS and chloride above background
concentrations but less than their 2L Standards. This indicates groundwater flow through the
western rim of the ash basin. The Seeps may represent preferential flow paths."
Investigation activities commenced in March 2016 to delineate the horizontal extent of impacted
groundwater and refine understanding of hydrogeologic properties in this area$. The potential for
impacts to residential wells located west of the impoundment is unclear until the extent of
contaminated groundwater leaving the ash basin is defined. In the mean time, the extent of ash -
contaminated groundwater that has migrated from the west side of the ash basin has yet to be
identified. The Duke acknowledgement9 that ash -contaminated groundwater is flowing from the ash
basin toward an adjacent drainage to the west, including an area off of BCSS property, is evidence that
the groundwater model, which includes a no -flow boundaries along the west side of the impoundment,
does not simulate real-world conditions.
Determination of Background Water Quality
Accurate and appropriate determination of background water quality is of critical importance to
evaluation of groundwater impacts from the ash basins. Proposed Provisional Background
Concentrations (PPBCs) for groundwater10, as well as other media, were established in the CAP Part 1.
The CAP Part 2 reported analytical results from rounds 1 thru 4 of background groundwater
sampling", but further evaluation of results and PPBCs was deferred to future reports. Groundwater
monitoring results are being compared to PPBCs that are based on an incomplete and un -evaluated
data set. Because of the high potential for the currently un -evaluated background data set to contain
spurious or unrepresentative data, interpretations that consider background concentrations are of
questionable value.
HDR, 2015c, p. 8
8 HDR, 2015c, p. 8
9 HDR, 2015c, p. 3
10 HDR, 2015c, Table 2-2
" HDR, 2015c, Section 2.4
on

GEO-HYDRO, INC
The current PPBCs 12 utilized data sets from a variety of sources including background wells from the
Pine Hall and Craig Road Landfills that are located on the opposite side of Belews Lake. Further, the
value selected as the PPBC was with few exceptions the highest value recorded at any of the various
locations. Water quality monitoring results are easily influenced by sampling methods and techniques
and can easily provide spurious data, especially when data from a variety of different sampling
programs are included. Consistent selection of the highest concentrations of each parameter from
multiple locations and sampling programs is very likely to skew the PPBC toward unreasonably high
values.
Even the background data set that is being developed by sampling new background wells around the
BCSS are capable of producing outliers in the data set. Review of the available background
groundwater data being developed at BCSS showed multiple analyses that should be tested as potential
outliers. For example, the new well data set for monitoring well BG -3S is summarized in the
following table.
Monitoring Data From Well BG -3S
Data from Cap Part 2, Table 2-6
Cursory review of this data shows that the highest recorded concentration of each of the listed
parameters was measured during the second round of sampling. This may represent a sporadic change
in water quality, but it may also represent an issue with sampling or analytical procedures. The
complete data set must be tested to eliminate unreasonable high values. Decisions about remedial
strategies to be utilized to clean-up or at least temporarily contain ash -related contaminants must not be
based on incomplete or skewed background data.
Groundwater Modeling
A groundwater flow and transport model of the site was constructed and used in the CAP, Parts 1 and 2
to evaluate groundwater flow and contaminant transport and investigate remedial scenarios. The
model domain was defined by placing no -flow boundaries around the west, south, and east sides of the
ash basin in locations coincident with topographic highs. The location of the model boundaries very
close to the sides of the basin eliminated all but six residential pumping wells from the model domain.
Effects of pumping in all of the remaining residential wells are not considered in the model.
'Z HDR, 2015c, Table 2-2
7
Round 1
Round 2
Round 3
Round 4
Cobalt
0.53
1.9
0.35J
0.24J
Iron
50U
5500
81
160
Manganese
29
130
19
16
Vanadium
lU
9.2
0.38J
0.69J
Data from Cap Part 2, Table 2-6
Cursory review of this data shows that the highest recorded concentration of each of the listed
parameters was measured during the second round of sampling. This may represent a sporadic change
in water quality, but it may also represent an issue with sampling or analytical procedures. The
complete data set must be tested to eliminate unreasonable high values. Decisions about remedial
strategies to be utilized to clean-up or at least temporarily contain ash -related contaminants must not be
based on incomplete or skewed background data.
Groundwater Modeling
A groundwater flow and transport model of the site was constructed and used in the CAP, Parts 1 and 2
to evaluate groundwater flow and contaminant transport and investigate remedial scenarios. The
model domain was defined by placing no -flow boundaries around the west, south, and east sides of the
ash basin in locations coincident with topographic highs. The location of the model boundaries very
close to the sides of the basin eliminated all but six residential pumping wells from the model domain.
Effects of pumping in all of the remaining residential wells are not considered in the model.
'Z HDR, 2015c, Table 2-2
7

GEO-HYDRO, INC
Remedial scenarios considered in the CAP Part I included the Existing Conditions Scenario, a Cap -in -
Place Scenario, and an Excavation Scenario. The Existing Conditions scenario 13 consists of modeling
constituent concentrations under existing conditions across the site for 250 years into the future. The
ash basin remains in place without modification and the source concentrations are held constant for the
entire modeled time period. The results of the modeling reported in CAP Part 114 showed that at the
end of 100 years, seven of eight modeled constituents were estimated to be above 2L standards at the
compliance boundary under the Existing Conditions scenario.
The Cap -In Place scenario 15 simulates placement of a low permeability cap over the ash basin to
prevent infiltration of precipitation or surface run-on. The description of this scenario in the CAP Part
116 further assumed that recharge and source -zone concentrations at the ash basins are set to zero. The
results of the modeling reported in CAP Part 117 showed that under the Cap -In -Place scenario
chromium, cobalt, thallium and arsenic were estimated to be above applicable standards at the
compliance boundary northwest of the ash basin after 100 years.
The Excavation scenario consisted of removal of the ash from the basin so that the sources of
contaminants both above and below the water table are removed. It simulates complete removal of the
ash by applying zero concentration levels to basin cells and setting recharge within the ash basin to
regional levels. Under the Excavation scenario cobalt was the only COI estimated to be present at
concentrations above applicable standards at the compliance boundary north of the ash basin dam.
Groundwater flow and transport modeling reported in CAP Part 2 included evaluation of the Existing
Conditions and Cap -In -Place scenarios. The description of the Existing Conditions scenario is
unchanged from that reported in CAP Part 1. The description of Cap -In -Place alternative in the CAP
Part 218 specifies that recharge is set to zero over the ash and that source concentrations remained
active as long as model cells remained wet. Despite the fact that modeling reported in CAP 1 showed
excavation of the ash to be the most protective of water quality over the next 100 years the Excavation
scenario was omitted without explanation from consideration in the CAP Part 2.
Predictions from the refined groundwater flow and transport models were reported in the CAP Part 219
The refined model predicts that:
• Concentrations of boron will exceed the 2L standard at the compliance boundary under the
Existing Conditions and Cap -In -Place scenario.
13 The description of this scenario is presented in HDR 2015b, Appendix C, Section 6.1
14 HDR, 2015b, page 76
15 The entire description of this scenario is presented in HDR 2015b, Appendix C, Section 6.2
16 HDR, 2015b, Appendix C, p.20
17 HDR, 2015b, page 76
18 HDR, 2015c, Appendix B, p. 20
19 HDR 2015c, Appendix B, p. 26
N.

GEO-HYDRO, INC
• Concentrations of cobalt will exceed the Interim Maximum Allowable Concentrations (IMAC)
at the compliance boundary under the Existing Conditions and Cap -In -Place scenarios.
Even though there are serious flaws in the groundwater modeling that artificially restrict groundwater
impacts under the cap -in-place scenario (see Opinion 3), the modeling effort confirms that ash
excavation is the option that is most protective of the environment and is a permanent solution.
X

GEO-HYDRO, INC
5. Opinion 1: Coal Ash Stored in the Belews Creek Ash Basin is the
Source of Contamination Detected in Surface Water and
Groundwater
The CSA states that "Soil, groundwater, and surface water have been impacted by ash handling and
storage at the BCSS site "20. This statement was reinforced in the CAP Part 2 which states that
"COI sources at the BCSS site consist of the ash basin including the chemical pond and the pine
Hall Road Landfill"21. Coal ash is the source of contaminants detected in surface water and
groundwater at concentrations above applicable standards in the vicinity and downgradient of the
ash basin. Data collected during the CSA show that that ash basin pore water contains antimony,
arsenic, boron, chloride, cobalt, iron, manganese, selenium, thallium, TDS and vanadium at
concentrations greater than 2L or IMAC standards22. The contaminated pore water either migrates
laterally out of the impoundment with groundwater flow or is discharged into impoundment water
and discharged to Little Belews Creek and subsequently into the Dan River.
Further evidence that coal ash stored in the Belews Creek ash basin is contaminating groundwater
and surface water is provided by groundwater modeling results. Even though there are serious flaws
in the groundwater modeling the effort does show that excavation and removal of the ash caused the
concentration of ash—related contaminants to decline23.
20 HDR, 2015a, p. 114
2' HDR, 2015b, p. 54
22 HDR, 2015a, p. ES -6
23 HDR, 2015b, p. 75
10

GEO-HYDRO, INC
6. Opinion 2: Capping Coal Ash Located Within the Belews Creek
Ash Basin Will Not Protect Groundwater Quality Within or
Downgradient of the Basin
The proposed designation of the BCSS ash basin, via the CAMA process, as low to medium risk
creates the possibility that Duke Energy (Duke) could pursue closure of the impoundment by
capping the disposed ash in place. Duke has indicated capping the ash in place is their preferred
source control option. Capping the waste within the footprint of the ash basin will not be protective
of groundwater quality downgradient of the basin.
Environmental contaminants contained in coal ash are leached into groundwater when precipitation
infiltrates through the waste from above or, when groundwater flows through waste that has been
placed below the water table. In the case of the BCSS ash basin, both of these processes are
currently acting to create the contaminated ash porewater, groundwater, and surface water that
discharge into Little Belews Creek and contaminate surface water downstream of the impoundment.
The Cap -In -Place remedy would likely reduce the amount of water that enters the waste from
precipitation, at least initially. This remedy would however do nothing to reduce the amount of
water that flows laterally into the basin from surrounding geologic materials and subsequently
through the capped waste. The thickness of ash that is estimated would remain saturated in the basin
were the Cap -In -Place remedy implemented has not been divulged in any of the reviewed
documents. Discussion of the Cap -In -Place scenario included in the CAP Part 124 indicates that the
CAP -In -Place scenario would lower the water table near the center of the basin by approximately
15 -feet and that "a portion of the ash in the basin remains saturated"
The results of the initial groundwater modeling were reported in CAP Part 125. This model showed
that under the Cap -In -Place scenario chromium, cobalt, thallium and arsenic were estimated to be
above applicable standards at the compliance boundary northwest of the ash basin after 100 years.
Predictions from the refined groundwater flow and transport model were reported in the CAP Part
2 26 . The refined model predicts that concentrations of boron will exceed the 2L standard and cobalt
will exceed the IMAC at the compliance boundary under the Existing Conditions and Cap -In -Place
scenarios. However, the groundwater model has been constructed in a manner that artificially
restricts groundwater flow into and out of the ash, thus making the Cap -In -Place option seem more
effective (See Opinion 3) should realistically be expected..
24 HDR, 2015b, p. 73
25 HDR, 2015b, p. 76
26 HDR 2015c, Appendix B, p. 26
11

GEO-HYDRO, INC
7. Opinion 3: The Groundwater Flow and Transport Model Does
Not Reflect Real -World Conditions
Groundwater models can be useful tools that can be employed to evaluate alternative actions at
waste disposal site such as BCSS. This usefulness, however, is predicated on the model being
constructed in a manner that faithfully recreates actual field conditions. In this case, the model
includes fundamental inconsistencies between observed and modeled conditions that cast doubt on
results and make it likely that the nature and extent of groundwater contamination is understated. If
a decision to accept a less than optimally protective remediation of the BCSS site is being
considered, it should minimally be based on a model that accurately reflects site conditions. Each of
the identified issues with the current model are identified separately below.
Boundary Conditions
The groundwater model was constructed with model boundaries that coincide with topographic
divides. It also assumes that groundwater divides underlie the topographic divides and could be
specified as no -flow boundary conditions in the model. No -flow boundaries are used where there is
no flow into or out from the model from or to the rest of the world. The western, southern and
eastern sides of the model domain were defined as no -flow boundaries 27 based upon topographic
divides, not groundwater data. Unfortunately, the CSA identified impacted seeps located in the
drainage to the west of the ash basin. This finding shows that the boundary conditions of the model
are demonstrably not correct on the west side of the mode128. Despite the fact that the seep
discharges demonstrate the invalidity of the conceptual and numerical basis of the model,
simulations of remedial options based upon the computational predictions of a demonstrably
erroneous model are being used to support risk-based remedial options.
Isolation of Ash
The layering of ash used in the model flow model effectively works to artificially constrain the
calculated flow of water into/out of the ash layers. The MODFLOW code used to model the
impoundment calculates head and groundwater flux between each side, top, and bottom of adjacent
cells. The cross-section included in Figure 4 shows the geometry of cells and materials types used to
model groundwater at the BCSS site. The ash in model layers 1-4 has no lateral continuity with any
of the adjacent natural materials in the sides of the basin. The layers extend laterally to the edge of
the basin and terminate at a no flow boundary. Lateral flow of groundwater from/to the sides of the
basin into the ash is not considered in this model. When a 100% effective cap is assumed (also a no -
27 HDR, 2015b, Appendix C, page 15 and Figure 4.
28 The boundary conditions on the south and east sides of the basin are also in question. An investigation of the area
around Seep S-9 is currently being conducted to determine the source of ash -impacted water in this area. Groundwater
flow from the east side of the ash basin, across the assumed no -flow boundary, toward Belews Lake is indicated on the
water table and deep zone potentiometric surface maps.
12

GEO-HYDRO, INC
flow condition), the only flow into or from the ash of layers 1-4 is vertically into or out of the
underlying saprolite through the bottom of layer 4 (and top of layer 5). This prohibition of lateral
flow at the edges of the ash pond into/from the enclosing saprolite is compounded by the
corresponding imposition of the horizontal -to -vertical anisotropy for hydraulic conductivity. As
modeled, the vertical flow between the ash and saprolite is constrained by hydraulic conductivity
that is only 10% that of the which would exist were the connection between the materials to occur
horizontally under the same gradients.
Fixed Concentration Cells Below the Ash
There is no expectation that ash is found anywhere but in model Layers 1 — 4. However, the model
assigns fixed concentrations to 4174 cells in saprolite Layer 5. Water cannot migrate out of the ash,
except by way of Layer 5. The transport model MT3DMS assigns the fixed concentration value in
Layer 5 to water within and leaving the Layer 5 cell regardless of the concentration entering the cell
from the ash in Layer 4 above. A comparison of the fixed concentrations in Layer 5 to the overlying
Layer 4 values establishes that the transport model redistributes the high boron contamination in
Layer 4 to a footprint in Layer 5 that is only 80% as large, but with a total mass of contaminant that
is 126% of that leaving layer 4. The rationale for this manipulation is not provided but may have
been an adjustment made during model calibration. There is no combination of chemical or physical
mechanisms that could produce such patterns; it is an artificial manipulation of the transport for
reasons neither discernible nor explained.
Assumption of Cap Effectiveness
The Cap—In-Place scenario assumes construction of a 100% effective cap over the ash in Layer 1.
While zero infiltration through the cap and into the ash is an easy assumption to make, in the real
world some infiltration through even the most robust cap systems is expected. When an assumed
100% effective cap over the top of the ash is combined with lateral isolation of the ash by no -flow
boundaries (described above), the only flow in the ash of layers 1-4 is vertically into or out of the
underlying saprolite through the bottom of layer 4. This is an assumed condition that has no basis in
the real world. Specific cap materials must be identified and a realistic estimate of infiltration and
lateral flow must be incorporated into the model if the Cap -In -Place scenario is to be seriously
evaluated.
13

GEO-HYDRO, INC
8. Opinion 4: Monitored Natural Attenuation Is Not An Acceptable
Groundwater Remediation Strategy at Belews Creek
The CAP29 indicates that Duke may evaluate Monitored Natural attenuation as a potential
groundwater remedy for certain area of the BCSS site. The CAP attempts to make it appear that
Monitored Natural Attenuation (MNA) is a viable remedial option for impacted downgradient of the
BCSS ash basin. However, NINA is not a viable closure option for this site for several reasons
including the following:
• Duke Energy has not proposed removal of the waste for disposal in a secure
location. Even the modeling presented in the CAP Part 2 shows that boron and
cobalt groundwater impacts downgradient of the impoundment would persist for
well over a century after the ash is capped -in-place. Groundwater will continue to
discharge from the sides of the basin into the ash. Saturated ash will continue to
leach metals into groundwater that will flow toward and eventually discharge into
the Dan River. As a practical matter, in the absence of removal all sources of
contamination cannot be controlled
• Many of the ash -related constituents in groundwater at this site neither degrade
nor attenuate. The discussion of MNA included in the Cap Part 230 states that
boron, TDS and sulfate are generally not attenuated, but concentrations are
reduced by diffusion, mechanical mixing, and/or dilution. The processes of
diffusion31, mechanical mixing32, and dilution33 are distinctly different processes
than degradation or attenuation. Because of this, MNA would not be an
acceptable remedy under North Carolina regulations.
29 HDR, 2015c, p.47
30 HDR, 2015c, p.55
31 Diffusion is movement of contaminants in the direction of their concentration gradient
32 Mechanical mixing is dispersion of contaminants that is caused by the motion of the water
33 Dilution is a reduction in contaminant concentration caused by addition of lower concentration water
14

GEO-HYDRO, INC
9. Opinion 5: Excavation of the Coal Ash Will Remove the Source
and Reduce the Concentration and Extent of Groundwater
Contaminants
Excavation and removal of the ash in the BCSS ash basin was evaluated in the CAP Part 1 but was
omitted from the CAP Part 1 without explanation. Excavation of the coal ash from the Belews
Creek ash basin would remove the source, and thereby reduce the concentration, extent, and
persistence of groundwater and surface water contaminants below the impoundment compared to
any other option. The groundwater flow and transport model of the site was used in the CAP Part
134 to evaluate groundwater flow and investigate three remedial scenarios. The results of the
modeling reported in CAP Part 1 showed that at the end of 100 years, seven of eight modeled
constituents were estimated to be above 2L standards under the Existing Conditions scenario. Under
the Cap -In -Place scenario chromium, cobalt, thallium and arsenic were estimated to be above
applicable standards at the compliance boundary northwest of the ash basin after 100 years. Cobalt
was the only COI estimated to be present at concentrations above applicable standards at the
compliance boundary north of the ash basin dam under the excavation scenario.
34 HDR, 2015b, page 74
15

GEO-HYDRO, INC
10. Opinion 6: The Coal Combustion Residual Impoundment Risk
Classification Proposed by NCDEQ Improperly Minimizes
Protection of Environmental Quality
A risk ranking process was specified in CAMA to determine the type of closure permitted at each
facility. The law specifically requires NCDEQ to classify each impoundment as either high-risk,
intermediate -risk, or low-risk, based on consideration, at a minimum, of all of the following criteria.
(1) Any hazards to public health, safety, or welfare resulting from the impoundment.
(2) The structural condition and hazard potential of the impoundment.
(3) The proximity of surface waters to the impoundment and whether any surface waters are
contaminated or threatened by contamination as a result of the impoundment.
(4) Information concerning the horizontal and vertical extent of soil and groundwater
contamination for all contaminants confirmed to be present in groundwater in exceedance of
groundwater quality standards and all significant factors affecting contaminant transport.
(5) The location and nature of all receptors and significant exposure pathways.
(6) The geological and hydrogeological features influencing the movement and chemical and
physical character of the contaminants.
(7) The amount and characteristics of coal combustion residuals in the impoundment.
(8) Whether the impoundment is located within an area subject to a 100 -year flood.
(9) Any other factor the Department deems relevant to establishment of risk.
In order to evaluate each impoundment on the nine criteria the NCDEQ established a risk
classification group35. The Risk Classification Group was broken into three sub -groups of people
based on areas of expertise (Groundwater, Surface Water, and Dam Safety) to develop a set of risk
factors to address each of the nine required criteria. Each subgroup reportedly placed a primary
emphasis on risk as it relates to the public from a groundwater, surface water, and dam safety
perspective and established one key factor that "plays a significant role in assigning an overall
classification" for that group. Other factors not identified as Key Factors were supposedly used to
"refine the risk classification and address the actual or potential risk to the environment and natural
resources."
The result of the risk classification methodology utilized by NCDEQ is that environmental and
ecologic risks posed by the BCSS site were not fully considered by NCDEQ when establishing the
overall site risk and clean-up priority. This resulted in an overall Low to Intermediate Risk rating, a
rating that essentially ignores the known environmental impacts of the BCSS ash basin. For
" NDEQ, 2016, p. 13, Classification Methodology
16

GEO-HYDRO, INC
example, Table 1 provides a listing of the groundwater risk classification factors and associated
ratings for BCSS. Ten groundwater risk factors were established and received ratings by NDEQ. Of
the 10 rated factors, 7 received High or Intermediate/High Ratings and only 3 received ratings of
Low Risk. Seventy percent of the rated groundwater risk classification factors were rated High or
Intermediate/High Risk, yet NCDEQ gave BCSS an overall Low Risk Rating for Groundwater.
Table 1
Groundwater Risk Classification
Groundwater Factors
BCSS Rating
Number of downgradient receptors within 1500 feet of compliance boundary that
are potentially or currently known to be exposed to impacted water. (Key Factor)
Low Risk
Amount of stored CCR reported in an impoundment
High Risk
Depth of CCR with respect to the water table
High Risk
Exceedance of 2L or IMAC standards at or beyond the established CCR
compliance boundary
High Risk
Population served by water supply wells within 1,500 feet upgradient or side
gradient of the compliance boundary
Intermediate/High Risk
Population served by water supply wells within 1,500 feet downgradient of the
compliance boundary
Low Risk
Proximity of 2L or IMAC exceedances beyond the compliance boundary with
respect to water supply wells
High Risk
Groundwater emanating from the impoundment exceeds 2L or IMAC and that
discharges to a surface water body
High Risk
Ingestion of contaminated soil or fugitive emissions
Low Risk
Data Gaps and Uncertainty
High Risk
Table 2 provides a listing of the surface water risk classification factors and associated ratings for
BCSS. A total of eight surface water risk factors were rated by NCDEQ. Of the 8 rated factors, 5
were High or Intermediate Risk, and an additional 3 factors were rated as Low or Low/Intermediate
Risk. Only 38% of the rated surface water risk classification factors were rated Low or
Low/Intermediate Risk, yet NCDEQ gave BCSS an overall Low Risk Rating for Surface Water.
The preceding analysis uses the risk ratings applied by NCDEQ with no evaluation or judgment
about whether they were or were not appropriately applied. The risk ratings given to the BCSS ash
basin point out that protection of environmental and natural resources are not being treated as
priority issues by the North Carolina agency entrusted with the responsibility to do just that. The
approach utilized by NCDEQ effectively ignores impacts to the natural environmental and natural
resources, and even ignores future human users of the groundwater and surface water resources. It
appears that in the view of NCDEQ the only way that a site can be rated as Intermediate or High
Risk is if a facility is located within a 100 -year floodplain or if 11 or more people within 1,500 feet
of the compliance boundary are potentially or currently known to be exposed to ash -impacted
17

GEO-HYDRO, INC
groundwater36. It is hard to imagine that exposed persons 1 through 10 would agree with this rating
scheme.
Table 2
Surface Water Risk Factors
Surface Water Factors
BCSS Rating
Landscape Position and Floodplain (Key Factor)
Low Risk
NPDES Wastewater and Ash Disposal Methods
High Risk
Impoundments Footprint Siting in Natural Drainage Way or
Stream
Low/ Intermediate Risk
Potential to Impact Surface Water Based on Total Ash Amount at
Facility
High Risk
Potential to Impact Surface Water Based on Dilution
Intermediate Risk
Development Density of Single -Family Residences along
Lake/Reservoir Shoreline
Low Risk
Classification of the Receiving Waters
Intermediate/ High Risk
Proximity to Water Supply Intake
Intermediate Risk
36 NCDEQ, 2016, page 15, Key Factors

GEO-HYDRO, INC
References
NCDEQ, 2016, Coal Combustion Residual Impoundment Risk Classifications, January 2016.
NCDENR, 2012, Permit to Discharge Wastewater Under the National Pollutant Discharge
Elimination System, Permit NC0024406, October, 2012.
HDR, 2015a, Comprehensive Site Assessment Report, Belews Creek Steam Station, Belews Creek,
NC, September 2015.
HDR, 2015b, Corrective Action Plan, Part 1, Belews Creek Steam Station, Belews Creek, NC,
December 2015.
HDR, 2015c, Corrective Action Plan, Part 2, Belews Creek Steam Station, Belews Creek, NC,
March 2016.
United States Geological Survey, Cluster Springs VA. — N.C., 7.5 Minute Topographic Map, 1968,
photorevised 1987.
19

GEO-HYDRO, INC
Figures

I� d. I ^ 'S
d
I '4 i . 5�5' I I4, �—_
'I �lY 1 1. �V •.
-J* ,��J i
• � It ' I 5i 4, 4_�; �1 .il. d,r
f
14 y i -
Y
�1
JX1
f
!I
=
iz
14
n
t F
------------
�.
to
�.�
17
r
. flet_
_
F}j A
t '
{
`.
f
'rr
14
■ II � � _ Fy � �
`
r" r�
� �d —' � �`
Poygr
' Feb. 4
_. e ■
I u� ,,
_�
'. "�',--�"•` � ,`
��• `, � ,4. 4, � 9,
in
,,` a
10.
-- - -
GEO-HYDRO, INC
Image taken from
USGS Belews Lake, NC
Figure l
Ash Pond Location and Topography
Consulting in Geology and Hydrogeology
2000
Belews Creek Steam Station

Map reproduced from Figure 2
GEO-HYDRO, INC HDR, 2015c, Areas ofExceedance
Consulting in Geology and Hydrogeology Figure 2-5 Belews Creek Steam Station

r /
f. ,'I �i_k`reJ�✓ i 1 E�I€F3VY 1` { i � ,
s . ry.es DUKE ENEMY
—
„t t M1: f 0 r
r
--: Y'6 J fkDUKE
F•x�.+ ,fie
DUI - _
ENERGY
I ID
3 r1r44� �^
t;
LEGEND
!S5 4
'r..' I k %-,y,. .. _ l 1 i' -: IJ APPROXIMATE GROUNDWATER FLOW DIRECTFON
'.' '-• Y — �"1 -SI l' - - - LL
ITVA_ �u BASIN
IASSSESSSMENT GROUNDWATER
lXy.l*' :�iIEP•r 1.! MONITOASH RING
WELL GROUNDWATER
r� � MONITORNG WELL
ASH BA IINVOLUN RY GROUNDWATER.
� S � ASSUMED PRIVATE WATER SUPPLY WELL
FIELD IDENTIFIED PRIVATE WATER SUPPLY WELL
PUBLIC WATER SUPPLY WELL
RECORDED PRNATE WATER SUPPLY WELL
REPORTED PRIVATE WATER SUPPLY WELL
_ `ESD-� pp �1 a
LE CONTOUR LINE
J ASHBASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE
BOUNDARY COINCIDENT
WITH DUKE ENERGY PROPERTY BOUNDARY
ASH BAS IN WASTE BOUNDARY
/ / iI� A x •i - _ _ _ DUKE ENERGY PROPERTY BOUNDARY
MIDDLEYON QIP ROAD d� 1 I Jll � f, _ _ _ LANDFILL COMPLIANCE 1OE BOUNDARY
� 4 a" - '♦� ! '�-' - LANDFILL FACILITY BOUNDARY
P� i fff
STRUCTURAL FILL, ASH LANDFILL^EDGE OF
WASTE
STREAM
CUM EMEROY
GEO-HYDRO, INC
Consulting in Geology and Hydrogeology
#'r
Map reproduced from
HDR, 2015t,
Figure 2-3
NOTE:
ALL ELEVATIONS ARE REP ERENCED TO NORTH AMERICAN
VERTICAL DATUM OF 1 W (NA'VV08B).
Figure 3
Deep Potentiometric Surface
Belews Creek Steam Station

A&-
A'
r.
w
Figure 4
Image reproduced from
GEO-HYDRO, INC HDR, 2015c, Appendix B
Model Domain Cross -Section A -A'
Consulting in Geology and Hydrogeology Figure 2
Belews Creek Steam Station

CERTIFICATE OF SERVICE
I hereby certify that the foregoing Expert Reports for the Belews Creek Steam Station
were served on all parties by depositing a true and correct copy in the U.S. Mail, first-class
postage prepaid, addressed as follows:
Anita LeVeaux
Frank E. Emory
Amy Bircher
Brent Rosser
Carolyn McLain
Nash Long
Francisco Benzoni
Melissa Romanzo
T. Hill Davis
Emma C. Merritt
N.C. Department of Justice
Hunton & Williams, LLP
P.O. Box 629
Bank ofAmerica Plaza
Raleigh, NC 27602-0629
101 South Tryon Street, Suite 3 500
[e-mail]
Charlotte, NC 28280
[e-mail]
[e-mail]
[e-mail]
[e-mail]
[e-mail]
[e-mail]
[e-mail]
[e-mail]
[e-mail]
Charles D. Case
McGuire Woods, LLP
James P. Cooney, III
434 Fayetteville Street
Womble Carlyle Sandridge
Suite 2600
& Rice, LLP
Raleigh, NC 27601
One Wells Fargo Center,
[e-mail]
Suite 3500
301 South College Street
Charlotte, NC 28202
[e-mail]
This the 13th day of May, 2016.
Myra Blake