NC0004961_2018 Riverbend Final Excavation Plan_20181204

Riverbend Steam Station
Coal Ash Excavation Plan
fie DUKE
*%, ENERGY
2018 Update

Table of Contents
I.
Statement of Purpose...................................................................................................................1
II.
General Facility Description.........................................................................................................2
III.
Project Charter...............................................................................................................................4
IV.
Critical Milestone Dates................................................................................................................4
V.
Erosion and Sediment Control Plan...........................................................................................
5
VI.
Dewatering Plan............................................................................................................................
5
VII.
Location(s) for Removed Ash......................................................................................................6
VIII.
Transportation Plan.......................................................................................................................6
IX.
Environmental and Dam Safety Permitting Plan......................................................................
7
X.
Contracting Strategy.....................................................................................................................8
XI.
Environmental, Health, and Safety Plan....................................................................................9
XII.
Communications Plan...................................................................................................................9
XIII.
Glossary........................................................................................................................................10
XIV.
Reference Documents................................................................................................................11
Exhibits
Exhibit A: Excavation Soil Sampling Plan

Statement of Purpose
Duke Energy Carolinas, LLC (Duke Energy or the Company) is required by Part 11,
Section 3(b) of the Coal Ash Management Act of 2014 (Session Law 2014-122) (Coal
Ash Act or Act) to close, in accordance with Part 11, Section 3(c) the coal combustion
residuals (CCR) surface impoundments located at the Riverbend Steam Station
(Riverbend or Plant), National Pollutant Discharge Eliminations System Permit No.
NC0004961 in Gaston County as soon as practicable, but not later than August 1, 2019.
This Coal Ash Excavation Plan (Plan) represents activities to satisfy the requirements
outlined in Part II, Sections 3(b) and 3(c), Subparagraphs 1 and 2 of the Act and the
requests set forth in the North Carolina Department of Environment Quality's (NCDEQ)
August 13, 2014 letter titled "Request for Coal Ash Excavation Plans for Asheville
Steam Electric Generating Plant, Dan River Combined Cycle Station, Riverbend Steam
Station, L.V. Sutton Electric Plant" (NCDEQ Letter). The NCDEQ Letter specifically
requests that the Plan include 1) soil and sediment erosion control measures, 2)
dewatering, and 3) the proposed location(s) of the removed ash. These requirements
are found in this updated Plan.
This is a revision of the Coal Ash Excavation Plan dated December 1, 2017, which
covers the final phase of ash basin excavation activities, including the continuation of
basin dewatering, site maintenance, ash basin preparation, and ash removal from the
basins at Riverbend. The Plan has been updated and submitted to NCDEQ annually;
however, due to the completion of ash basin excavation activities by the applicable
CAMA deadline, no further updates will be made to the Plan.
The Plan covers some of the work required by Part II, Sections 3(b) and 3(c) of the Coal
Ash Act. The Act requires the closure of the ash basins as soon as practicable, but no
later than August 1, 2019. However, the Act contains no requirement for the submittal
of an excavation plan of the kind presented here. Thus, while the formulation, submittal,
and review of this Plan will assist in Duke Energy's work to close the ash basin, its
ultimate approval is an action not specifically required by statutory, regulatory, or other
applicable authority.
The scope of work in excavating the ash basins has been determined by applicable
laws, rules, permits, and approvals that control the activities to be performed under the
Plan. There are several external and internal factors that could potentially affect the
precise scope of the work to be performed under the Plan. As a consequence, neither
the submittal of this Plan nor its acknowledgement by NCDEQ should be taken as
requiring actions different from such applicable requirements. Duke Energy submits this
Plan to NCDEQ based on the understanding that it may be necessary to take actions
that deviate from the Plan in the future, and the Company reserves the right to make
such changes.
1: Riverbend

General Facility Description
Riverbend is located off Horseshoe Bend Beach Road near the town of Mt. Holly in
Gaston County, NC on the south bank of the Catawba River. The seven -unit Station
began commercial operation in 1929 with two units and then expanded to seven by
1954. At its peak, the generating facility had a capacity of 454 megawatts. As of
April 1, 2013, all of the coal-fired units were retired. Demolition was completed in June
2018.
The CCR from Riverbend's coal combustion operations was historically processed in
the ash basin system located on the northeast side of the property adjacent to the
Catawba River. The discharge from the ash basin system is permitted through Outfall
#002 to the Catawba River in the Catawba River Basin by NCDEQ's Division of Water
Resources under National Pollutant Discharge Elimination System (NPDES) Permit No.
NC0004961. Riverbend has been decommissioned, and no active ash placement or
sluicing is occurring within the ash basin system.
Duke Energy's Coal Combustion Residuals Removal Verification Procedure (Removal
Verification Procedure) will be used to verify that primary source ash has been removed
from the basin. Subsequent to removal of the ash pursuant to the Removal Verification
Procedure, Duke Energy will implement its Excavation Soil Sampling Plan (ESSP),
which was developed for the purpose of meeting the applicable performance standard.
Although not required under CAMA, in November 2016, NCDEQ sent Coal Combustion
Residuals Surface Impoundment Closure Guidelines for Protection of Groundwater to
Duke Energy instructing the Company to submit the ESSP to NCDEQ as part of the
site's excavation plan. In accordance with this directive, a copy of the ESSP is attached
as Exhibit "A" to this Plan.
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The ash basin system was an integral part of the station's NPDES permitted wastewater
treatment system, which predominantly received inflows from the ash removal system,
station yard drain sump, and stormwater flows. During station operations, inflows to the
ash basin were highly variable due to the cyclical nature of station operations. The ash
basin system consisted of a Primary Ash Basin and a Secondary Ash Basin, which were
separated by an Intermediate Dam. The Primary Ash Basin and the Secondary Ash
Basin are no longer separated since the decommissioning of the Intermediate Dam.
For the purpose of stormwater management, the Ash Stack was also within the ash
basin system.
The ash basin system was located approximately 2,400 feet to the northeast of the
power plant, adjacent to the Catawba River. The Primary Ash Basin is impounded by
an earthen embankment dam, referred to as Primary Dam (GASTO-97), located on the
2: Riverbend

west side of the Primary Ash Basin. The Secondary Ash Basin is impounded by an
earthen embankment dam, referred to as Secondary Dam (GASTO-98), located along
the northeast side of the Secondary Ash Basin.
Originally, the ash basin at Riverbend consisted of a single basin commissioned in
1957. In 1979, the original single basin was divided by constructing a divider dam
(Intermediate Dam (GASTO-99)) to form two separate basins (Primary Ash Basin and
Secondary Ash Basin). This modification improved the original basin's overall ability for
suspended solids removal. The Primary Dam was raised, and the Intermediate Dam
was built over sluiced ash to a crest of 730 feet mean sea level (msl). At the same time,
the Secondary Dam crest elevation remained at 720 feet msl. As part of the Excavation
Project, the Intermediate Dam was removed in February 2017. Prior to excavation, the
Primary Ash Basin and the Secondary Ash Basin were estimated to contain a total of
approximately 3.6 million tons of CCR. Based on the latest survey and estimate, this
total has been revised to 3.3 million tons. As of November 1, 2018, approximately 3.2
million tons of CCR material have been removed from the basin.
The inflows from the ash removal system and the station yard drain sump were directed
through sluice lines into the Primary Ash Basin. The discharge from the Primary Ash
Basin to the Secondary Ash Basin was through a concrete discharge tower located near
the divider dam. The surface area of the combined Ash Basin is approximately 69
acres with an approximate maximum basin elevation of 714 feet msl. The full basin
elevation of Mountain Island Lake is approximately 647 feet msl.
Prior to the station being retired, stormwater and wastewater effluent from other non -
ash -related station flows to the ash basin were discharged in compliance with the
station's NPDES permit to the Catawba River through a concrete discharge tower
located in the Secondary Ash Basin. The concrete discharge tower drained through a
30 -inch diameter corrugated metal pipe into a concrete -lined channel. The channel
extended from the Secondary Ash Basin to NPDES Outfall #002, which discharged to
the Catawba River. This discharge pipe has been grouted closed.
I_Fy1l7CLN:1
An ash fill deposit, known as the "Ash Stack," was constructed from ash removed from
the Primary and Secondary Ash Basins during basin clean-out projects. The Ash Stack
was utilized for periodic ash basin clean -outs to prolong the life of the ash basins. The
Ash Stack is a 29 -acre area located south of the Primary Ash Basin and contained
approximately 1.6 million tons of CCR. The Ash Stack was constructed during two ash
basin clean -outs; the last recorded ash basin clean-out project was in 2007. Prior to
Phase I excavation, the Ash Stack had 1.5 to 2 feet of soil cover and vegetation that
was maintained following the last deposition in this area. For the purpose of water
management, the stormwater run-off from the Ash Stack area is routed to the ash basin
3: Riverbend

system. As of November 1, 2018, approximately 1.56 million tons of CCR material have
been removed from the Ash Stack.
Cinder Pit and Other Identified Ash Storage Areas
Prior to construction of the ash basin, bottom ash (cinders) was deposited in a primarily
dry condition in the "Cinder Pit" and other areas near the cinder pit and coal pile. The
Cinder Pit is approximately 13 acres and is located in a triangular area northeast of the
coal pile and northwest of the rail spur. This area was utilized for storage of ash
material at the station prior to the installation of precipitators and a wet sluicing system.
The Cinder Pit contained predominantly dry cinders. As of November 1, 2018,
approximately 180,000 tons of CCR material have been removed from the Cinder Pit
area.
III. Project Charter
Dewatering of the ash basins and the removal of ash from the site is expected to
complete before the end of 2018. As of November 1, 2018, approximately 4.94 million
tons of ash have been excavated and removed from the site. Approximately 4.82
million tons were moved to an off-site structural fill and the remainder to off-site landfills.
Coal ash excavation at Riverbend is ongoing, including completion of the Removal
Verification Procedure.
The Riverbend NPDES wastewater permit was issued and became effective on
March 1, 2016. Decanting of bulk water began soon thereafter and continued until
halted in June 2016. In July 2016, NCDEQ imposed a new requirement to install a
physical -chemical treatment facility. Following installation of a water treatment facility,
bulk dewatering commenced in the fall of 2016 and was completed on January 31,
2017. Interstitial dewatering of the Primary and Secondary Ash Basins will continue
through completion of the project.
Droject Charter Scope
Phase II Scope
1. Complete closure activities for the Ash Basins.
Critical Milestone Dates
Critical Milestones within the Plan are summarized in the table below.
Submit Excavation Plan November 15, 2014 Completed
to NCDEQ November 13, 2014
Complete Comprehensive November 30, 2014 Completed
Engineering Review November 30, 2014
4: Riverbend

Erosion and Sediment Control Plan
The Erosion and Sediment Control (E&SC) plans for the excavation of the Ash Stack,
construction of the rail infrastructure, and haul roads were developed, submitted to
NCDEQ, and approved. All control measures will be maintained through the project in
accordance with the E&SC plans. When possible, portions of the E&SC plan will be
closed out at the approval of NCDEQ as areas become stabilized.
Dewatering
The Riverbend ash basins were dewatered to facilitate the removal of ash and to
mitigate risk. An engineered dewatering plan for Riverbend was developed, and bulk
dewatering was completed on January 31, 2017. Interstitial dewatering and stormwater
removal continue through the required water treatment components noted in the
previous phase of this Ash Plan.
.sn rsasin System
During excavation, contact water has been controlled and diverted through ditches and
pumps into sumps located within the area of the Basin. As water is collected in the
sump(s), it is pumped into one of the two lined holding ponds, which were constructed
to store water prior to treatment. Water from the holding pond(s) is pumped to the
wastewater treatment facility on site, treated, and discharged to the Catawba River, in
5: Riverbend
Excavation Plan
February 17, 2015
Completed
Acknowledgement b NCDEQ
February 2, 2015
Receive Industrial Stormwater
March 5, 2015
Completed
(ISW) Permit
May 15, 2015
Final permit approval
Completed
Commence Work — Ash Removal
+ 60 Days
May 21, 2015
After Receipt of ISW Permit
Submit Updated Excavation Plan
November 15, 2015
Completed
to NCDEQ
November 13, 2015
Submit Updated Excavation Plan
December 31, 2016
Completed
to NCDEQ
December 21, 2016
Submit Updated Excavation Plan
December 31, 2017
Completed
to NCDEQ
December 1, 2017
Eliminate Stormwater Discharge
December 31, 2018
On Track for
December 20, 2018
into Impoundments
Completion
Submit Final Updated Excavation
December 31, 2018
On Track
Plan to NCDEQ
Impoundments Closed per Part II,
Sections 3(b) and 3(c) of the
August 1, 2019
On Track
Coal Ash Act
Erosion and Sediment Control Plan
The Erosion and Sediment Control (E&SC) plans for the excavation of the Ash Stack,
construction of the rail infrastructure, and haul roads were developed, submitted to
NCDEQ, and approved. All control measures will be maintained through the project in
accordance with the E&SC plans. When possible, portions of the E&SC plan will be
closed out at the approval of NCDEQ as areas become stabilized.
Dewatering
The Riverbend ash basins were dewatered to facilitate the removal of ash and to
mitigate risk. An engineered dewatering plan for Riverbend was developed, and bulk
dewatering was completed on January 31, 2017. Interstitial dewatering and stormwater
removal continue through the required water treatment components noted in the
previous phase of this Ash Plan.
.sn rsasin System
During excavation, contact water has been controlled and diverted through ditches and
pumps into sumps located within the area of the Basin. As water is collected in the
sump(s), it is pumped into one of the two lined holding ponds, which were constructed
to store water prior to treatment. Water from the holding pond(s) is pumped to the
wastewater treatment facility on site, treated, and discharged to the Catawba River, in
5: Riverbend

accordance with the NPDES permit. Upon completion of ash excavation, the holding
ponds and the wastewater treatment facility will be decommissioned.
Location(s) for Removed Ash
A total of approximately 4.94 million tons of ash from the Ash Stack, ash basin system,
and Cinder Pit have been excavated and removed from the Riverbend site. Ash
removed from the site was transported by the contractor to permitted facilities.
uisposai Sites
A pilot program for ash removal began on May 21, 2015, to transport ash by truck to the
R&B Landfill in Homer, GA. Ash transport to the landfills located at the Marshall Steam
Station in Sherrills Ford, NC began on July 27, 2015. Initial ash shipments by truck
from Riverbend to the Brickhaven Structural Fill began on October 23, 2015. Ash
transportation to the R&B Landfill was terminated in September 2015, and ash
transportation to the Marshall Landfill was terminated in the first quarter of 2016. Early
in the first quarter of 2016, rail transport of the remaining ash commenced to the
Brickhaven Structural Fill.
R&B Landfill
A total of approximately 16,000 tons of ash were removed from the site and transported
to the R&B landfill in Homer, GA, which is a permitted facility.
Marshall FGD and Industrial Landfills
The FGD and industrial landfills are located at the Duke Energy Marshall Steam Station
facility in Sherrills Ford, NC. Both are permitted facilities, and 88,745 tons of CCR
material were relocated there.
Brickhaven Structural Fill
The Brickhaven Structural Fill is located at the Brickhaven Mine near the City of
Moncure in Chatham County, NC. It resides on approximately 299 acres. Ash
transported there is beneficially used as structural fill material at the reclaimed mine. A
total of approximiately 4.82 million tons were relocated to the Brickhaven Structural Fill.
VIII. Transportation Plan
The majority of Ash was transported off-site via rail car. As previously noted in Section
VII above, a pilot program for ash removal began with the transportation of ash by truck
to the R&B Landfill in Homer, Georgia, Marshall Steam Station landfills, and the
6: Riverbend

Brickhaven Structural Fill. Truck transportation ceased and was replaced by rail
transportation.
Environmental and Dam Safety Permitting Plan
Excavation of ash creates potential for stormwater impacts. The facility holds approved
E&SC plans and associated Construction Stormwater Permits for ash removal. Also,
NCDEQ indicated that an NPDES Industrial Stormwater Permit is required to transport
ash. The Company received the Industrial Stormwater Permit to support ash removal at
the site. Pursuant to the requirements of the Industrial Stormwater Permit, a stormwater
pollution prevention plan (SPPP) incorporating best management practices was created
and is currently being implemented. Future modifications to the permit/plan will be
managed as necessary.
On February 12, 2016, NCDEQ issued NPDES Permit NC0004961 for operation of the
wastewater treatment works at Riverbend and for discharging treated wastewater to the
Catawba River (Mountain Island Lake) and associated tributaries and wetlands. Certain
effluent limits (pH and total hardness) in the permit were subsequently modified under
that certain Special Order by Consent (EMC SOC WQ S16-005) dated November 10,
2016 (SOC).
There are no jurisdictional wetlands/streams associated with the removal of the Ash
Stack or Primary or Secondary Ash basins in Phase I. Future wetland/stream impacts
and jurisdictional determinations will be managed through the United States Army Corps
of Engineers with attention paid to the difference between jurisdictional
wetlands/streams under Section 404 and those arising from Section 401 waters.
Riverbend ash is a non -hazardous material.
All necessary Dam Safety approvals have been obtained to cover activities on or
around jurisdictional dams. Dam decommissioning plans for the Primary and
Secondary dams have been submitted and approved by NCDEQ Dam Safety. Any
impacted wells or piezometers will be abandoned in accordance with NCDEQ
requirements. Fugitive dust will be managed to mitigate impacts to neighboring areas.
Additional site-specific or local requirements will be secured, as needed.
Permit Matrix
IMF—
PERMIT
NCDEQ issued the ISW
NPDES Industrial
May 15, 2015 (R)
permit on May 15, 2015.
Stormwater Permit
SPPP implementation date
was November 15, 2015.
7: Riverbend

Contracting Strategy
The Ash Management Program strategy is to engage multiple contractors, drive
competition, create system -wide innovation, and develop a collection of best practices.
Duke Energy engaged contractor(s), who are experienced in coal ash excavation,
transportation, and disposal, and continues to evaluate other potential contractors. The
Company provides in-depth oversight, coordination, and monitoring of the contractors to
8: Riverbend
NPDES Wastewater
Q1 2016 (R)
Permit became effective
Permit — Major
(modified by SOC in
December 1, 2016.
Modification
Q4 2016)
Jurisdictional
Wetland and Stream
There are no identified
Impacts
N/A
jurisdictional wetland/stream
404 Permitting and
impacts.
401 WQC
Intermediate Dam
Submitted May 31, 2016 and
Decommissioning
June 16, 2016 (R)
received approval June 16,
Request Approval
2016. Decommissioning
completed March 13, 2017.
Submitted on May 8, 2017.
Primary Dam
Received approval August 3,
Dam Safety
Modification Request
August 3, 2017 (R)
2017. Modification completed
Approval
March 3, 2018.
Primary and
Secondary Dam
Resubmitted May 29, 2018.
Decommissioning
June 7, 2018 (R)
Received approval June 7,
Request Approval
2018.
Individual Structural
Mine Reclamation
Fill Permit
October 15, 2015 (R)
Owner/Operator obtained an
Waste
(Permit to Operate)
Individual Structural Fill
Permit pursuant to G.S. §
130A-309.219.
Original permit received April
Duke Energy
Water Conveyance
August 2, 2016 (R)
7, 2016. Amended permit for
Lake Services
Permit
revised quantities received
August 2, 2016.
Site-specific
Other
Nuisance/Noise/Odor
N/A
None identified.
Requirements
Other Requirements,
including DOT
Requirements
Contracting Strategy
The Ash Management Program strategy is to engage multiple contractors, drive
competition, create system -wide innovation, and develop a collection of best practices.
Duke Energy engaged contractor(s), who are experienced in coal ash excavation,
transportation, and disposal, and continues to evaluate other potential contractors. The
Company provides in-depth oversight, coordination, and monitoring of the contractors to
8: Riverbend

ensure the work is performed appropriately. Duke Energy's core values include safety,
quality, and protection of the environment, which are incorporated into our contracts.
The Company continues to evaluate alternate approaches, methods, and contracting
solutions and will adjust its strategy, as necessary.
XI. Environmental, Health, and Safety Plan
The Company is committed to the health, safety, and welfare of employees, contractors,
and the public, and to protecting the environment and natural resources. During all
phases of the project work, the Company and its contractors will follow the Duke Energy
Safe Work Practices Manual, the Environmental, Health, and Safety supplement
document, and any additional requirements. Occupational health and safety
expectations include oversight and continuous improvement throughout the project.
The project includes comprehensive environmental, health, and safety plans
encompassing all aspects of the project work. In addition to adhering to all applicable
environmental, health, and safety rules and regulations, Duke Energy and its
contractors will focus on ensuring the safety of the public and protection of the
environment during each phase of the project.
XII. Communications Plan
The project team has coordinated with Duke Energy's Corporate Communications
Department to develop a comprehensive external communications plan tailored to the
specific needs of each phase of the project. Many different external stakeholders,
including neighbors, government officials, and media have an interest in this project.
The Company is committed to providing information by proactively communicating
about the project activities to potentially affected parties and responding to inquiries in a
timely manner.
9: Riverbend

XIII. Glossary
TERM
DEFINITION
Synonymous with Coal Combustion Residual Impoundment. A
topographic depression, excavation, or dammed area that is
primarily formed from earthen materials; without a base liner
approved for use by Article 9 of Chapter 130A of the North
Carolina General Statutes or rules adopted thereunder for a
Ash Basin
combustion products landfill or coal combustion residuals landfill,
industrial landfill, or municipal solid waste landfill; and an area
that is designed to hold accumulated coal combustion residuals
in the form of liquid wastes, wastes containing free liquids, or
sludge, and that is not backfilled or otherwise covered during
periods of deposition.
Ash Stack
A dry ash storage feature external to the ash basin.
Projects promoting public health and environmental protection,
Beneficial Use
offering equivalent success relative to other alternatives, and
preserving natural resources.
The agglomerated, angular ash particles formed in pulverized
coal furnaces that are too large to be carried in the flue gases
Bottom Ash
and collect on the furnace walls. Bottom ash falls through open
grates to an ash hopper at the bottom of the furnace.
Water above the ash contained in the ash basin. Synonymous
Bulk Water
with free water.
Coal Ash
Plan required by NCDEQ letter dated August 13, 2014, including
Excavation Plan
a schedule for soil and sediment erosion control measures,
dewatering, and the proposed location of the removed ash.
Coal Ash Management
North Carolina Session Law 2014-122.
Act of 2014
Coal Combustion
Residuals, including fly ash, bottom ash, boiler slag, mill rejects,
Residuals (CCR)
and flue gas desulfurization residue produced by a coal-fired
generating unit.
Dewatering
The act of removing bulk and entrapped water from the ash
basin.
Duke Energy
Safe Work
Document detailing the Duke Energy safety guidelines.
Practices Manual
10: Riverbend

XIV. Reference Documents
REF]LI
DOCUMENT
I
Flowable water below the ash surface, which creates hydrostatic
Entrapped Water
August 13, 2014
pressure on the dam.
Tasks and work performed related to the planning, engineering,
Excavation Activities
and excavation of ash from an ash basin.
Excavation Plan
Refer to Coal Ash Excavation Plan.
July 20, 2016
Water above the ash contained in the ash basin. Synonymous
Free Water
with bulk water.
Very fine, powdery material, composed mostly of silica with
nearly all particles spherical in shape, which is a product of
Fly Ash
burning finely ground coal in a boiler to produce electricity and is
removed from the plant exhaust gases by air emission control
devices.
NPDES
National Pollutant Discharge Elimination System.
A permit that regulates the direct discharge of wastewater to
NPDES Permit
surface waters.
Federal, state, county, or local government authorizing
Permit
document.
XIV. Reference Documents
REF]LI
DOCUMENT
I
1
NCDEQ Letter to Duke Energy, Request for Excavation
August 13, 2014
Plans
2
Coal Ash Management Act of 2014
September 20, 2014
3
NCDEQ Letter from Jeff Poupart, Water Quality Permitting
July 20, 2016
Section Chief, to Duke Energy regarding decant
11: Riverbend