NC0004961_2017 Excavation and Soil Sampling Plan_20171205

Riverbend Steam Station
Coal Ash Excavation Plan
('DUKE
ENERGY
2017 Update

Table of Contents
I.
Statement of Purpose...................................................................................................................1
II.
General Facility Description.........................................................................................................2
III.
Project Charter...............................................................................................................................4
IV.
Critical Milestone Dates................................................................................................................6
V.
Erosion and Sediment Control Plan...........................................................................................
6
VI.
Dewatering Plan............................................................................................................................
6
VII.
Location(s) for Removed Ash......................................................................................................7
VIII.
Transportation Plan.......................................................................................................................8
IX.
Environmental and Dam Safety Permitting Plan......................................................................8
X.
Contracting Strategy...................................................................................................................11
XI.
Environmental, Health, and Safety Plan..................................................................................11
XII.
Communications Plan.................................................................................................................11
XIII.
Glossary........................................................................................................................................12
XIV.
Reference Documents................................................................................................................13
Exhibits
Exhibit A: Excavation Soil Sampling Plan

I. Statement of Purpose
Duke Energy Carolinas, LLC (Duke Energy or the Company) is required by Part II,
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 II, 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 (NC DEQ)
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" (NC DEQ Letter).
The NC DEQ Letter was sent by the North Carolina Department of Environment and
Natural Resources, which was renamed the North Carolina Department of
Environmental Quality by Session Bill 2015-241. The NC DEQ 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 21, 2016, which
covers the initial phase of ash basin excavation activities, including the initiation of basin
dewatering, site preparation, ash basin preparation and ash removal from the basins at
Riverbend. The Plan will generally be updated and submitted to NC DEQ annually.
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 NC DEQ should be taken as
requiring actions different from such applicable requirements. Duke Energy submits this
Plan to NC DEQ based on the understanding that it may be necessary to take actions
1: Riverbend

that deviate from the Plan in the future, and the Company reserves the right to make
such changes.
II. General Facility Description
Riverbend is located off of 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.
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 NC DEQ'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, NC DEQ sent Coal Combustion
Residuals Surface Impoundment Closure Guidelines for Protection of Groundwater to
Duke Energy instructing the Company to submit the ESSP to NC DEQ 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.
Ash Basin System
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
current ash basin system consists 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 is also
within the ash basin system.
The ash basin system is 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
2: Riverbend

earthen embankment dam, referred to as Primary Dam (GASTO-97), located on the
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 an October 2017 survey, this total has
been revised to 3.1 million tons.
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
extends from the Secondary Ash Basin to an NPDES Outfall #002 that discharged to
the Catawba River. This discharge pipe has been grouted closed.
Ash Stack
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 1.4 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
3: Riverbend

management, the stormwater run-off from the Ash Stack area is routed to the ash basin
system.
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 contains predominantly dry cinders and is currently covered with dense
vegetation. The Cinder Pit contains approximately 203,000 tons of CCR.
Project Charter
Dewatering of the ash basins and the removal of ash from the site will be performed
within project phases. As of November 1, 2017, 3.5 million tons of ash have been
excavated. Approximately 3.4 million tons were moved to an off-site structural fill and
the remainder to off-site landfills. The project has completed Phase I and is now
implementing Phase 11.
The following items in Phase I have been completed or initiated:
1. Developed and installed approved erosion and sediment control measures.
2. Developed and constructed the infrastructure to remove and transport the ash.
3. Completed the installation of a wastewater treatment system to support
dewatering of the ash basins.
4. Began dewatering of the Primary and Secondary Ash Basins.
5. Completed the work scope and bid event to support ash basin closure.
6. Completed the removal of the first 2 million tons of ash from the Riverbend site.
7. Development of option(s) for proposed ash disposal or beneficial use locations.
8. Validated production rates to meet project requirements.
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, NC DEQ 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
throughout Phase 11.
4: Riverbend

Project Charter Objectives
Phase II Objectives
1. Continue to dewater ash basins, pumping water through the on-site water
treatment facility.
2. Submit and obtain any necessary permits for Phase II activities.
3. Excavate and transport ash from the Ash Stack, Cinder Pit, Primary Ash Basin,
and Secondary Ash Basin
4. Gain knowledge and opportunities for continuous program improvement.
Inactive Ash Areas Objectives
1. Submit and obtain any necessary permits.
2. Excavate and transport ash from the Cinder Pit.
3. Gain knowledge and opportunities for program improvement.
Project Charter Scope
Phase II Scope
1. Install and/or maintain site erosion and sediment control measures.
2. Maintain and continue to utilize rail for the transportation of ash from Riverbend.
3. Excavate and transport the remaining ash from the Ash Stack and Ash Basins to
an approved disposal site.
4. Reroute and stop remaining inflows into the ash basins.
5. Continue dewatering the Ash Basin using the on-site wastewater treatment
facility.
6. Decommission the Intermediate Dam. (Completed)
7. Plan activities for subsequent work.
8. Assess, including delineation, the potential remediation efforts in the Cinder Pit.
9. Submit and/or obtain remaining required permit applications for ash removal
activities for subsequent work.
10. Complete closure activities for the Ash Basins.
Inactive Ash Areas Scope
1. Dewater the Cinder Pit and manage stormwater and contact water, as needed.
2. Excavate and transport the 203,000 tons of material from the Cinder Pit to an
approved disposal site.
3. The Cinder Pit will be closed as part of overall site closure, but is not subject to
the requirements of Part II, Sections 3(b) and 3(c) of the Coal Ash Act.
5: Riverbend

IV. Critical Milestone Dates
Critical Milestones within the Plan are summarized in the table below.
MILESTONE•
LATER THAN DATE
STATUS
Submit Excavation Plan
November 15, 2014
Completed
November 13, 2014
Complete Comprehensive
November 30, 2014
Completed
Engineering review
November 30, 2014
Excavation Plan
February 17, 2015
Completed
Acknowledgement by NC DEQ
February 2, 2015
Receive Industrial Stormwater
March 5, 2015
Completed
ISW Permit
May 15, 2015
Commence work — ash removal
Final permit approval + 60
Completed
Days
May 21, 2015
after receipt of ISW Permit
Submit Updated Excavation Plan
November 15, 2015
Submitted on November 13,
2015
Submit Updated Excavation Plan
December 31, 2016
Submitted on December 21,
2016
Submit Updated Excavation Plan
December 31, Annually
On track
Eliminate stormwater discharge
December 31, 2018
On track
into impoundments
Impoundments closed per Part II,
August 1, 2019
On track
Sections 3(b) and 3(c) of the Coal
Ash Act
V. 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 NC
DEQ, and approved. Modifications from E&SC plans for subsequent phase(s) will be
approved by NC DEQ prior to installation and initiation of subsequent phase work.
The approved contractor will install the E&SC measures indicated in the plan. 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
NC DEQ as areas become stabilized.
VI. Dewatering Plan
The Riverbend ash basins continue to be dewatered to facilitate the removal of ash and
to mitigate risk. An engineered dewatering plan for Riverbend has been 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.
6: Riverbend

Ash Basin System
During excavation, contact water is being controlled and diverted through ditches and
pumps into a sump located within the area of the Basin. Additional sumps will be
utilized during excavation. 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 accordance with the NPDES permit.
The permitted discharge outfall for the wastewater treatment plant is SW002. Free
water has been removed from the ash basin system. Following rain events,
accumulated stormwater is removed at a maximum rate of two feet over a 24-hour
period.
Location(s) for Removed Ash
The Plan includes the excavation and removal of a total of approximately 4.7 million
tons of ash from the Ash Stack, ash basin system, and Cinder Pit. Ash removed from
the site is being transported by the contractor to permitted facilities.
Uispusai cites
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 Sherrill's 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 ash commenced to the Brickhaven Structural
Fill and is expected for the duration of this phase and scope. Eventually, as the
excavation and transportation comes to a close, rail transport may taper off and be
replaced, again, by truck transport before completion.
R&B Landfill
A total of 15,762 tons of ash has been 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.
7: Riverbend

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.
Contingent Plan. Disposal Sites
In the event of any issues with accepting ash at the Brickhaven Structural Fill, the
undeveloped Colon Structural Fill located in Sanford, NC has been determined as a
suitable alternative site. Ash may be transported from Riverbend to the Colon Structural
Fill to be beneficially used as fill material for a structural fill project at the reclaimed
mine.
Transportation Plan
Ash is currently being transported off-site via rail car. The rail system has the ability to
load and transport at least 145,000 tons of ash per month to the Brickhaven Structural
Fill. That system will continue until the end of the project, when only a small amount of
ash will need to be relocated by truck transportation. Transportation is being conducted
by approved transporters and will meet Department of Transportation (DOT) and other
applicable federal, state, and local regulations.
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, GA, Marshall Steam
Station landfills, and the Brickhaven Structural Fill. Truck transportation has halted and
been replaced by rail transportation. In the future, trucking will remain an option to
support of ash transportation by rail.
Environmental and Dam Safety Permitting Plan
Excavation of ash creates potential for stormwater impacts. The facility holds approved
erosion and sediment control plans and associated Construction Stormwater Permits for
ash removal. Also, NC DEQ has 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 has been created and is currently being implemented. Future
modifications to the permit/plan will be managed as necessary.
On February 12, 2016, NC DEQ 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
8: Riverbend

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 particular 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.
Subsequent phase(s) will include dewatering and continued excavation and removal of
ash from the Ash Basins, Ash Stack, and Cinder Pit locations.
All necessary Dam Safety approvals will be or have been obtained to cover activities on
or around jurisdictional dams. Breaching of the dams will require Dam Safety approval.
Any impacted wells or piezometers will be abandoned in accordance with NC DEQ
requirements. Fugitive dust will be managed to mitigate impacts to neighboring areas.
Additional site-specific or local requirements will be secured, as needed.
9: Riverbend

Permit Matrix
MEDIA
PERMIT
RECEIVED D• -COMMENTS
TARGETD.
NPDES Industrial
May 15, 2015 (R)
Previous Target Date was
Stormwater Permit
March 5, 2015. SPPP
implementation date was
November 15, 2015.
NPDES Wastewater
First quarter 2016 (R)
Previous Target Date was
Permit — Major
(modified by SOC in
August 28, 2015. Permit
Water
Modification
fourth quarter 2016)
became effective December
1, 2016.
Jurisdictional
N/A
There are no identified
Wetland and Stream
jurisdictional wetland/stream
Impacts / 404
impacts.
Permitting and 401
WQC
Intermediate Dam
June 16, 2016 (R)
Submitted May 31, 2016
Decommissioning
Decommissioning completed
Request Approval
March 13, 2017.
Primary Dam
August 3, 2017 (R)
Submitted on May 8, 2017
Modification Request
Approval
Modification is to remove the
Dam Safety
top 10 feet of soil from the
dam that is partially founded
on ash.
Primary and
June 1, 2018 (T)
Breaching of dike will require
Secondary Dam
Dam Safety approval.
Decommissioning
Request Approval
Individual Structural
October 15, 2015 (R)
Mine Reclamation
Fill Permit
(Permit to Operate)
Owner/Operator obtained an
Waste
individual structural fill permit
as set forth in Part II, § 130A-
309.219 of the Coal Ash Act.
Water Conveyance
August 2, 2016 (R)
Original permit received
Duke Energy
Permit
April 7, 2016. Amended
Lake Services
permit for revised
quantities received August
2, 2016.
Site-specific
None identified.
Nuisance/Noise/Odor
N/A
Other
/Other Requirements,
Requirements
including DOT
Requirements
10: Riverbend

X. 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 has 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
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
Protecting workers, the public, the community, and the environment
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 is coordinating 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.
11: Riverbend

XIII. Glossary
TERM
DEFINITION
Ash Basin
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
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
Beneficial Use
Projects promoting public health and environmental protection,
offering equivalent success relative to other alternatives, and
preserving natural resources
Bottom Ash
The agglomerated, angular ash particles formed in pulverized
coal furnaces that are too large to be carried in the flue gases
and collect on the furnace walls. Bottom ash falls through open
grates to an ash hopper at the bottom of the furnace.
Bulk Water
Water above the ash contained in the ash basin. Synonymous
with free water
Coal Ash Excavation
Plan required by NC DEQ letter dated August 13, 2014, including
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
12: Riverbend

XIV. Reference Documents
Entrapped Water
7FIlowable water below the ash surface, which creates hydrostatic
NC DEQ Letter to Duke Energy, Request for Excavation Plans
essure on the dam
Excavation Activities
Tasks and work performed related to the planning, engineering,
2014
and excavation of ash from an ash basin
Excavation Plan
Refer to Coal Ash Excavation Plan
Free Water
Water above the ash contained in the ash basin. Synonymous
2014
with bulk water
Fly Ash
Very fine, powdery material, composed mostly of silica with
nearly all particles spherical in shape, which is a product of
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
NPDES Permit
A permit that regulates the direct discharge of wastewater to
surface waters
Permit
Federal, state, county, or local government authorizing document
XIV. Reference Documents
13: Riverbend
1
NC DEQ Letter to Duke Energy, Request for Excavation Plans
August 13,
2014
2
Coal Ash Management Act of 2014
September 20,
2014
3
NC DEQ Letter from Jeff Poupart, Water Quality Permitting Section
July 20, 2016
Chief, to Duke Energy regarding decant
13: Riverbend

EXCAVATION SOIL SAMPLING PLAN
RIVERBEND STEAM STATION
ASH BASIN SYSTEM
FOR ASH BASIN EXCAVATION
NORTH CAROLINA ASH BASIN CLOSURE
DUKE ENERGY CAROLINAS, LLC.
526 SOUTH CHURCH STREET/ECI3K
CHARLOTTE, NORTH CAROLINA 28202
� DUKE
ENERGY
Waste & Groundwater Programs
Revision 1
December 2017

Excavation Soil Sampling Plan December 2017
Riverbend Steam Station Ash Basin System Revision 1
TABLE OF CONTENTS
SECTION PAGE
1.0 PURPOSE..........................................................................................................................1
2.0 DOCUMENTATION SUMMARY...............................................................................1
3.0 SOIL SAMPLING METHODOLOGY.........................................................................1
3.1 Method Summary........................................................................................................1
3.1.1 Equipment...............................................................................................................2
3.1.2 Sample Locations................................................................................................... 3
3.1.3 Collection of Representative Samples................................................................. 3
3.1.4 Sample Preservation, Containers, Handling and Storage ................................ 4
3.1.5 Decontamination....................................................................................................4
4.0 VISUAL CONFIRMATION OF ASH REMOVAL .................................................... 4
4.1 Pre -Excavation Documentation................................................................................. 4
4.2 Ash Removal Verification Protocol...........................................................................
5
4.2.1 Field Documentation.............................................................................................
5
4.2.2 Fill Evaluation Criteria..........................................................................................
6
4.3 Visual Removal Not Applicable................................................................................
6
5.0 SOIL SAMPLING AND ANALYSIS...........................................................................
7
5.1 Soil Sampling................................................................................................................
7
5.1.1 Scenario 1................................................................................................................
7
5.1.2 Scenario 2................................................................................................................
7
5.2 Fate and Transport Modeling.....................................................................................
8
TABLE 2 - Soil Parameters and Analytical Methods Totals and SPLP Analysis
North Carolina Ash Basins to Be Closed Via Excavation ..........................................
9
FIGURE 1 - Riverbend Steam Station Sample Grid ..................................................
10
Page i

Excavation Soil Sampling Plan December 2017
Riverbend Steam Station Ash Basin System
1.0 PURPOSE
Revision 1
The purpose of this Excavation Soil Sampling Plan is to provide a standardized method for collecting soil
samples at Duke Energy North Carolina ash basins that are to be closed via excavation. Soil samples are
being collected following all visible ash removal from certain ash basins to support closure activities.
This Excavation Soil Sampling Plan is applicable to the collection of representative soil samples. Analysis
of soil samples may be chemical or physical in nature and may be used to determine the following:
• Extent and magnitude of constituent occurrence
• Input concentrations for groundwater fate and transport model
The methodologies discussed in this Excavation Soil Sampling Plan are applicable to the sampling of soil
in ash basin excavation areas. For the purposes of this plan, soils are those mineral and organic
materials remaining after all visible ash has been excavated.
2.0 DOCUMENTATION SUMMARY
TABLE 1 - Post Ash Basin Excavation Soil Data Collection
Task
Description
Test
Depth
Visual Inspection on 100' X 100'
Visually confirm primary source
removal at nodes (Figure 1) and
N/A
N/A
grid node
document with photographs.
Soil sample analysis on 100' X
Collect representative samples at
1
0 - 6 inches
100' grid node
nodes (Figure 1) the appropriate
PLM
2 2.5'
depths.
0 - 6 inches'
Soil Sample Analysis on an acre
Collect representative samples at the
Total Metals
2 2.5
2
grid system
appropriate depths.
SPLP
7
12'- 12. 12.5'
17'- 17.5'
Notes:
' If a certain six-inch sample interval does not yield sufficient soil volume to fill five 8 -ounce sample bottles, the
sample interval may be expanded two twelve inches to allow for sufficient soil sample volume. The revised sample
interval should be appropriately documented.
2Excavation is complete once confirmed by visual inspection and PLM analysis per Section 4.0.
3.0 SOIL SAMPLING METHODOLOGY
3.1 Method Summary
This Excavation Soil Sampling Plan has been adapted from Environmental Protection Agency (EPA)
Standard Operating Procedures (SOPS) #2012 and #2006 and North Carolina Department of
Environmental Quality (NC DEQ) Attachment 1 Coal Combustion Residuals Surface Impoundment
Closure Guidelines for Protection of Groundwater, November 4, 2016.
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
Soil samples are collected directly using stainless steel or plastic trowel, spade, shovel, or scoops.
Following collection, soil is transferred from the sampling device to a stainless steel or plastic bowl to be
homogenized. Once homogenized, the soil is transferred into Duke Energy Laboratory supplied sample
bottles.
Soil samples will be submitted under chain of custody for the following analyses: total metals and
Synthetic Precipitation Leaching Procedure (SPLP) metals. Analytical methods for total metals and SPLP
metals are described in Table 2. Ash presence is quantitatively determined by polarized light
microscopy (PLM) by RJ Lee Laboratory (or other approved vendor). PLM analysis passes visible light
through a pair of polarizing filters to create optical effects used in identifying unknown materials. This
method is commonly used in asbestos and coal ash identification.
3.1.1 Equipment
• Stainless steel or plastic trowel, scoop, spade or shovel — Used for collecting soil samples
from surface locations.
• Sample containers —To be supplied by Duke Energy Laboratory with appropriate
cooler(s). Estimated that five 8 -ounce sample bottles with Teflon -lined lids will be
required for each sample location and sample depth. For return of cooler to the lab, ice
will be required.
• Gloves — Used for personal protection and to prevent cross -contamination of samples —
nitrile, disposable, powderless.
• Field clothing and Personal Protective Equipment — Used as specified in the site Health
and Safety Plan.
• Sampling flags — Used for identifying soil sampling locations.
• Field notebook — A bound book used to record progress of sampling effort and record
any problems and field observations during sampling.
• Three-ring binder book — Used to store necessary forms and record and track samples
collected at the site.
• Permanent marking pen — Used to label sample containers, document field logbooks,
data sheets and chain of custody.
• Stainless steel or plastic spoon — Used for homogenizing soil samples within a stainless
steel or plastic bowl.
• Stainless steel or plastic bowl — Used for homogenizing soil samples, when applicable.
• Camera — Used for photo -documentation of sample locations and samples.
• GPS — Device used to obtain elevation, latitude and longitude of sample location.
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
Trash bag — Used to dispose of gloves and any other non -hazardous waste generated
during sampling.
• Decontamination supplies and equipment.
3.1.2 Sample Locations
General locations for soil sampling are determined by the soil scientist in the field at a rate of
one soil sample for every 1 acre of ash basin area excavated. Actual sampling locations on site
may vary to account for site conditions and to allow collection of representative samples.
Representative samples reflect areas where all ash has been visually excavated and natural soil
is observed.
3.1.3 Collection of Representative Samples
For the purpose of this plan, surface soil is considered to range from 0 to 6 inches in depth,
while deeper samples will be collected at a range of 2 to 2.5 feet below ground surface (bgs), 7
to 7.5 feet bgs, 12 to 12.5 feet bgs, and 17 to 17.5 feet bgs (Table 1) unless bedrock, refusal, or
the water table are encountered. A surface soil sample and deeper samples will be collected at
each location for every 1 acre of ash basin excavated. A new pair of nitrile gloves is worn at
each sampling location and each depth. Each sampling location is recorded on the site map
prior to collecting the sample if location is not already noted on the map. The GPS location of
each sampling location (i.e. elevation, latitude and longitude), sample descriptions, and area
photographs are also recorded. All sampling equipment is decontaminated prior to use
irrespective of depth. The following procedure will be used to collect representative soil
samples with a scoop, shovel, trowel, geoprobe, or excavator:
• Locate general sampling locations.
• Determine suitability of sampling location for a representative sample.
• If sampling location appears to reflect representative conditions that would allow
collection of a representative sample, proceed with sampling procedure. If
location is not indicative of conditions that would allow collection of a
representative sample, notify the project manager so an alternate location can
be identified.
• Using a decontaminated sampling instrument, remove the desired thickness and
volume of soil from the sampling area. The sampler must obtain enough soil to
fill five 8 -ounce sample bottles. If a certain six-inch sample interval does not
yield sufficient soil volume to fill five 8 -ounce sample bottles, the sample interval
may be expanded to allow for sufficient soil sample volume. The revised sample
interval should be appropriately documented.
Transfer the sample into an appropriate sample or homogenization bowl. Non-
dedicated containers should be adequately decontaminated. Stir for
approximately one minute until there appears to be a uniform color and
consistency.
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
Transfer homogenized sample to a labeled container(s) of appropriate size and
construction for the analyses requested.
• Secure sample container tightly.
3.1.4 Sample Preservation, Containers, Handling and Storage
Chemical preservation of soils is generally not recommended. Cooling to 4°C on wet ice is
usually the best approach, supplemented by the appropriate holding time for the analyses
requested.
The Duke Energy Laboratory will supply the appropriate sample bottles for the collected soil
samples. The sample volume is a function of the analytical requirements and the Duke Energy
Laboratory will ensure the appropriate number of bottles are supplied. Ensure chain of custody
is completed for sample bottle return to the Duke Energy Laboratory.
Table 2 contains a list of parameters to be analyzed with corresponding reporting units and
analytical methods. If a parameter or group of parameters is not included in Table 2, the
laboratory performing the analysis should be contacted to determine the appropriate sample
bottles, volumes, and preservatives.
All non -dedicated sampling devices should be decontaminated and wrapped in plastic. The
sampling device should remain in this wrapping until it is needed. Each sampling device should
be used for only one sample and then decontaminated or disposed of. Non -dedicated sampling
devices should be cleaned in the field using the decontamination procedure described below.
3.1.5 Decontamination
Decontamination procedures can be time consuming; having a sufficient quantity of sampling
tools available is recommended. All non -dedicated sampling equipment must be
decontaminated prior to reuse. Equipment decontamination consists of:
1. Detergent wash and brush cleaning
2. Tap water rinse
3. De -ionized water rinse
4. Air dry
Wrap sampling tools with plastic
4.0 VISUAL CONFIRMATION OF ASH REMOVAL
4.1 Pre -Excavation Documentation
Closure by removal is defined herein as removing the primary source (primary source of potential
constituents of interest) to the point that ash is not visible to the unaided eye at the ground surface.
Primary source ash is the main body of ash that was deposited in the basin. This method is intended
solely to verify and document primary source ash removal and is not intended to validate environmental
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
quality standards of the subsurface (considered the secondary source of potential constituents of
interest). Pre -excavation documentation would consist of:
• Review topographic mapping, aerial photography, construction drawings, and boring logs to
estimate the pre -ash placement topography and/or ash/soil interface
• Preparation of an ash basin figure illustrating a grid spacing of 100 feet (Figure 1). Each grid
point (node) will be assigned a unique identifier. Each node of the grid spacing (grid point) will
represent a visual verification location.
4.2 Ash Removal Verification Protocol
Ash excavation will be considered complete based on visual confirmation that all ash has been removed.
Ash removal will be based on sampling of the ash/soil interface and analysis by PLM. Soil samples will
be examined utilizing methods outlined in American Society for Testing and Materials (ASTM) D2488,
Standard Practice for Description and Identification of Soils (Visual -Manual Procedure). Vertical and
horizontal excavation of ash can terminate when the remaining material can be documented using PLM
to contain less than 50% ash.
Project will excavate ash until a visible change in color or texture confirms removal. This location shall
be referred to as the ash/soil interface. If visual evaluation is inconclusive, then request additional
evaluation to confirm ash removal.
4.2.1 Field Documentation
Evaluate the excavated surface elevation relative to the pre -ash placement topography.
Periodically check bottom elevation to evaluate if fill is present above historic bottom elevation.
Visual confirmation will be performed on a 100 -foot grid system (Figure 1), unless conditions
prevent such confirmation, as described in Section 4.3. Soil sampling will be performed on a
100 -foot grid system and will be analyzed using PLM.
• Personnel will locate each node by GPS or survey control, determine elevation, and
evaluate whether that point is above or below the historic bottom elevation.
• Personnel will then observe the surface area represented by the node, to note if visible
ash is present at the surface. If present, the location should be documented and
excavation will need to continue. If the evaluation indicates the surface soils are
residuum or bedrock, then hand auger to two feet below surface (or refusal) and
perform visual -manual classification of the soils at the surface and depth according to
ASTM method D2488. Submit sample from surface and depth (or shallower if refusal)
for PLM analysis. The conditions shall be documented by taking photographs.
• The classification indicator for fly ash will be grey to black silt -sized particles with no
plasticity. The classification indicator for bottom ash will be grey to black sand to gravel
sized particles and porous. If the material cannot be positively identified as soil, submit
a sample for PLM analysis.
• If the node point elevation is near the historic bottom elevation and either (1) residuum
is indicated by observation or (2) soil is confirmed by visual manual classification (ASTM
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
D2488) and PLM analysis is less than 50%, then personnel can conclude the primary
source is removed.
4.2.2 Fill Evaluation Criteria
The following procedure provides an approach that can be used to ascertain if the fill can remain
in place. The procedure specified is based on the fill material and depth.
If the elevation is less than eight feet above the historic bottom elevation and residuum
is not observed, then test pits may be excavated to historic bottom elevation or until
residuum or bedrock is encountered, but no more than eight feet below the surface.
o Personnel will evaluate existing information to determine if the test pits are
necessary. If necessary, personnel may recommend excavating test pits at a
frequency no tighter than 100 feet by 100 feet.
o If visible ash is not discovered based on information defined above, then the
primary source removal may be confirmed.
o If visible ash is discovered, then continue excavation.
• If the elevation is more than eight feet above historic bottom elevation and residuum is
not observed, discuss with CCP Closure Personnel.
o CCP Closure Personnel will confirm historic information and recommend a
drilling and sampling program at a frequency no tighter than 100 feet by 100
feet to evaluate the presence of ash below the fill in accordance with the
information defined above. If unusual features are revealed by the drilling, CCP
Closure Engineering may request/recommend additional borings. Exploration is
to be performed by continuous sampling during drilling.
o If visible ash is not discovered based on information defined above, then the
primary source removal may be confirmed.
o If visible ash is discovered, then continue excavation.
4.3 Visual Removal Not Applicable
If possible, excavation of ash should continue even if groundwater is encountered. Visual
documentation cannot be completed where ash is under the water table. If Duke Energy cannot
complete visual removal because of site conditions or other restricting factors, documentation shall be
presented to NC DEQ.
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Excavation Soil Sampling Plan December 2017
Riverbend Steam Station Ash Basin System Revision 1
5.0 SOIL SAMPLING AND ANALYSIS
5.1 Soil Sampling
Soil sampling of the remaining soils (less than 50% ash per PLM analysis) will be necessary to evaluate
the extent of potential secondary source impacts depending on the depth of the water table and any
proposed institutional or engineering controls that may be used in the area of excavation. Soil sampling
will not be required if refusal or the top of bedrock are encountered or the remaining soils are below the
water table. Soil samples for laboratory analysis must be collected in a manner that will ensure a
relatively uniform distribution of particles throughout the six inch sample.
The systematic approach and design for soil sampling an analysis is dependent upon two scenarios:
• Scenario 1: Remaining soil (containing less than 50% ash per PLM analysis) is located above the
seasonal high water table and final constructed institutional and/or engineering controls will
restrict infiltration from the surface reaching the water table (e.g. installation of a liner system).
Scenario 2: Remaining soil (containing less than 50% ash per PLM analysis) is located above the
seasonal high water table and infiltration from the surface would continue to reach the water
table.
5.1.1 Scenario 1
Confirmation sampling will include discrete surface samples collected from the first six inches of
the soil. Sampling will be performed on an acre grid system. This sample collection
methodology shall be sufficient to characterize the horizontal extent of any remaining potential
secondary source impacts for comparison with the NC DEQ Preliminary Soil Remediation Goals
(PSRG). The samples shall be analyzed by a North Carolina certified laboratory for total
concentrations for the following parameters: antimony, aluminum, arsenic, barium, beryllium,
boron, cadmium, calcium, chloride, chromium (total and hexavalent), cobalt, copper, iron, lead,
magnesium, manganese, mercury, molybdenum, nickel, nitrate as nitrogen, pH, potassium,
selenium, silver, sodium, strontium, sulfate, thallium, vanadium, and zinc. No SPLP testing is
required.
5.1.2 Scenario 2
Confirmation sampling will include collection of both discrete surface and subsurface soil
samples performed on an acre grid system. Discrete surface samples will be collected from the
first six inches of the soil and a subsurface soil sample will be collected at 2 to 2.5 feet below
ground surface (bgs), 7 to 7.5 feet bgs, 12 to 12.5 feet bgs, and 17 to 17.5 feet bgs unless refusal,
bedrock, or the water table are encountered. The use of a geoprobe or excavator is anticipated.
This sample collection methodology shall be sufficient to characterize both the horizontal and
vertical extent of any remaining potential secondary source impacts for comparison with the NC
DEQ PSRGs and/or input into the soil leachate model. The samples shall be analyzed by a North
Carolina certified laboratory for both total concentrations and SPLP for the following
parameters: antimony, aluminum, arsenic, barium, beryllium, boron, cadmium, calcium,
chloride, chromium (total and hexavalent), cobalt, copper, iron, lead, magnesium, manganese,
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
mercury, molybdenum, nickel, nitrate as nitrogen, pH, potassium, selenium, silver, sodium,
strontium, sulfate, thallium, vanadium, and zinc.
5.2 Fate and Transport Modeling
Contingency for stabilization of remaining amounts of potential secondary source impacts in a manner
that will meet the intent of North Carolina Groundwater 2L Rules and closure requirements shall be
considered as site conditions dictate. Provisions to develop groundwater flow and transport models to
evaluate protection of groundwater criteria if some secondary source impacts are left in place shall be
considered. In addition, the possibility of metals leaching from a potential change in pH and
geochemical conditions related to dewatering and excavation shall be considered along with plans for
groundwater models to assess resulting site conditions.
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Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
December 2017
Revision 1
TABLE 2 - Soil Parameters and Analytical Methods Totals and SPLP Analysis
North Carolina Ash Basins to Be Closed Via Excavation
INORGANIC COMPOUNDS
UNITS
METHODl
Aluminum
mg/kg or µg/I
EPA 6010D
Antimony
mg/kg or µg/I
EPA 6020B
Arsenic
mg/kg or µg/I
EPA 6020B
Barium
mg/kg or µg/I
EPA 6010D
Beryllium
mg/kg or µg/I
EPA 6020B
Boron
mg/kg or µg/I
EPA 6010D
Cadmium
mg/kg or µg/I
EPA 6020B
Calcium
mg/kg or µg/I
EPA 6010D
Chloride
mg/kg or µg/I
EPA 9056A
Chromium
mg/kg or µg/I
EPA 6010D
Cobalt
mg/kg or µg/I
EPA 6020B
Copper
mg/kg or µg/I
EPA 6010D
Hexavalent Chromium
mg/kg or µg/I
EPA Method
7199/218.7
Iron
mg/kg or µg/I
EPA 6010D
Lead
mg/kg or µg/I
EPA 6020B
Magnesium
mg/kg or µg/I
EPA 6010D
Manganese
mg/kg or µg/I
EPA 6010D
Mercury
mg/kg or µg/I
EPA Method
7470A/7471B
Molybdenum
mg/kg or µg/I
EPA 6010D
Nickel
mg/kg or µg/I
EPA 6010D
Nitrate as Nitrogen
mg/kg or µg/I
EPA 9056A
pH
SU
EPA 9045D
Potassium
mg/kg or µg/I
EPA 6010D
Selenium
mg/kg or µg/I
EPA 6020B
Silver
mg/kg or µg/I
EPA 6020B
Sodium
mg/kg or µg/I
EPA 6010D
Strontium
mg/kg or µg/I
EPA 6010D
Sulfate
mg/kg or µg/I
EPA 9056A
Thallium (low level) (SPLP Extract only)
mg/kg or µg/I
EPA 6020B
Vanadium
mg/kg or µg/I
EPA 6020B
Zinc
mg/kg or µg/I
EPA 6010D
Notes:
1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH
using USEPA Method 9045, as noted above (or similar approved methods). Soil samples will
also be analyzed for leaching potential using SPLP Extraction Method 1312 in conjunction with
USEPA Methods 6010/6020 (or similar approved methods).
Page 9

Excavation Soil Sampling Plan
Riverbend Steam Station Ash Basin System
FIGURE 1- Riverbend Steam Station Sample Grid
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