Marshall CBE - Closure Plan_20200107

DUKE
ENERGY,
December 30, 2019
Ms. Sheila Holman
Assistant Secretary for Environment
North Carolina Department of Environmental Quality
1611 Mail Service Center
Raleigh, North Carolina 27699-1611
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
526 S. Church Street
Mail Code: ECUP
Charlotte, NC 28202
[phone]
Subject: Submittal of Ash Basin Closure Plan and Corrective Action Plan Update
Marshall Steam Station
Dear Ms. Holman:
In accordance with the requirements of N.C.G.S. §§ 130A-309.21 1 (b) and .214(a)(4), Duke
Energy provides the following documents: (1) a plan for basin closure by excavation, and (2) a
corrective action plan (CAP) for the Marshall site, which will address groundwater impacts within
9 years of full-scale operation, regardless of the specific closure method.
Closure by Excavation
The enclosed excavation plan is in response to NCDEQ's April 1 order requiring excavation of
the Marshall coal ash basin. After regulatory approval, excavating the basin ash would require
14 years to move the ash to a new lined landfill within plant property. The landfill would be
located partially within the prior footprint of the ash basin near Island Point Road, rising about
200 feet above Island Point Road.
Continuing to Protect Water Resources
Robust scientific study, conducted under the direction of NCDEQ, demonstrates that drinking
and recreational water supplies around the Marshall facility are well -protected from coal ash
impacts and will only continue to improve during and after closure. Ongoing research and
monitoring also provide a detailed understanding of groundwater conditions at the site,
indicating that the impact is highly localized and will be addressed through the planned CAP
approach. The CAP designed for Marshall will achieve groundwater remediation through a
combination of strategically placed groundwater extraction wells coupled with clean water
infiltration wells.
Prior to submission, the closure plan was reviewed by the National Ash Management Advisory
Board (NAMAB), which consists of nationally and internationally recognized and published
experts with practical experience working with and for the private sector, federal government,
and academia. NAMAB helped develop the guiding principles for safe basin closure and their
feedback is incorporated herein.
Duke Energy remains committed to safely and permanently closing basins in ways that continue
to protect people and the environment and welcomes the opportunity to work constructively with
NCDEQ to move forward.

Ms. Sheila Holman
December 30, 2019
Submittal of Ash Basin Closure Plan and Corrective Action Plan Update
Marshall Steam Station
Page 2
Since, ly,
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Enclosure:
• Corrective Action Plan Update
• Closure by Excavation Closure Plan

DUKE ENERGY
MARSHALL STEAM STATION
COAL COMBUSTION RESIDUALS
SURFACE IMPOUNDMENT CLOSURE
PLAN
CLOSURE BY EXCAVATION
CCR BASIN
Prepared for
� DUKE
` ° ENERGY,
Duke Energy Carolinas, LLC
400 South Tryon Street
Charlotte, North Carolina 28202
December 18, 2019
Prepared by
AECOM
1600 Perimeter Park Dr.
Morrisville, North Carolina 27560

AECOM December 18, 2019
Duke Energy — Marshall Steam Station
CCR Surface Impoundment CBE Closure Plan
TABLE OF CONTENTS
EXECUTIVE SUMMARY..........................................................................................................Vii
1. INTRODUCTION.............................................................................................................1
1.1 Background....................................................................................................................1
1.2 Closure Plan Objectives................................................................................................. 1
1.3 Report Organization....................................................................................................... 1
2. GOVERNING LAWS.......................................................................................................2
3. FACILITY DESCRIPTION AND EXISTING SITE FEATURES........................................2
3.1 Surface Impoundment Description.................................................................................. 2
3.1.1
Site History and Operations................................................................................2
3.1.2
Estimated Volume of CCR in Impoundments......................................................4
3.1.3
Description of Surface Impoundment Structural Integrity.....................................4
3.1.4
Sources of Discharges into Surface Impoundments............................................5
3.1.5
Existing Liner System.........................................................................................5
3.1.6
Inspection and Monitoring Summary.................................................................. 5
3.2 Site Maps....................................................................................................................... 6
3.2.1
Existing CCR Impoundment Related Structures.................................................6
3.2.2
Receptor Survey................................................................................................6
3.2.3
Existing On -Site Landfills................................................................................... 7
3.3 Monitoring and Sampling Location Plan.......................................................................... 7
4. RESULTS OF HYDROGEOLOGIC, GEOLOGIC, AND GEOTECHNICAL
INVESTIGATIONS..........................................................................................................8
4.1
Background....................................................................................................................8
4.2
Hydrogeology and Geologic Descriptions.......................................................................
8
4.3
Stratigraphy of the Geologic Units Underlying Surface Impoundments ............................
8
4.4
Geotechnical Properties.................................................................................................
8
4.4.1 CCR Within Basin..............................................................................................8
4.4.2 Liner Material Properties....................................................................................
9
4.4.3 Subsurface Soil Properties.................................................................................9
4.4.4 Basin Dam Soil Properties................................................................................
10
4.5
Chemical Analyses of Impoundment Water, CCR and CCR Affected Soil .....................
10
4.6
Historical Groundwater Sampling Results.....................................................................
10
4.7
Groundwater Potentiometric Contour Maps..................................................................
10
4.8
Estimated Vertical & Horizontal Extent of CCR within the Impoundments ......................
10
5. GROUNDWATER
MODELING ANALYSES.................................................................11
5.1
Site Conceptual Model Predictions...............................................................................
11
5.2
Groundwater Chemistry Effects....................................................................................
11
5.3
Groundwater Trend Analysis Methods..........................................................................
11
6. BENEFICIAL AND FUTURE USE.................................................................................12
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Duke Energy — Marshall Steam Station
CCR Surface Impoundment CBE Closure Plan
6.1 CCR Use...................................................................................................................... 12
6.2 Site Future Use............................................................................................................ 12
7. CLOSURE DESIGN DOCUMENTS..............................................................................12
7.1 Engineering Evaluations and Analyses......................................................................... 12
7.2 Closure Plan Activities.................................................................................................. 13
7.3 Closure Plan Drawings................................................................................................. 13
7.4 Description of the Construction Quality Assurance Plan ................................................ 14
8. MANAGEMENT OF WASTEWATER AND STORMWATER.........................................15
8.1 Anticipated Changes in Wastewater and Stormwater Management ............................... 16
8.2 Wastewater and Stormwater Permitting Requirements ................................................. 16
9. DESCRIPTION OF FINAL DISPOSITION OF CCR......................................................16
10. APPLICABLE PERMITS FOR CLOSURE....................................................................17
11. DESCRIPTION OF POST -CLOSURE MONITORING AND CARE................................17
11.1 Groundwater Monitoring Program................................................................................. 17
12. PROJECT MILESTONES AND COST ESTIMATES.....................................................18
12.1 Project Schedule.......................................................................................................... 18
12.2 Closure and Post -Closure Cost Estimate...................................................................... 18
13. REFERENCED DOCUMENTS......................................................................................20
PROFESSIONAL ENGINEER CERTIFICATION......................................................................21
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Tables
Table 2-1 NC CAMA Closure Plan Requirements, Summary and Cross Reference
Table
Table 4-1 Summary of Typical Geotechnical Material Properties
Table 10-1 Marshall Steam Station Regulatory Permits, Approvals, or Requirements
for Ash Basin Closure by Excavation
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Duke Energy — Marshall Steam Station
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Figures
Figure ES-1 Current Condition View
Figure ES-2 Post -Closure Condition View
Figure 1-1 Vicinity Map and Site Plan
Figure 3-1 Existing Conditions Plan
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Appendices
Appendix A Estimated Volume of CCR in Impoundment
Appendix B Geotechnical Data and Properties
Appendix 131 Logs of Borings and Monitoring Wells
Appendix B2 Results of Seismic Cone Penetration Testing (SCPTU)
Appendix B3 Results of Laboratory Testing
Appendix C Engineering Evaluations and Analyses
Appendix C1 Stormwater
Appendix C2 Soil Quantities
Appendix D Closure Plan Drawings
Appendix E Excavation Soil Sampling Plan
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EXECUTIVE SUMMARY
As required by the North Carolina Department of Environmental Quality's (NCDEQ) April 1, 2019
"Coal Combustion Residuals Surface Impoundment Closure Determination," (Closure
Determination), Duke Energy Carolinas, LLC (Duke Energy) has prepared this Closure Plan to
describe the closure of the coal combustion residuals (CCR) surface impoundment (Basin) at the
Marshall Steam Station (MSS). This plan details closure by excavation of the MSS Basin and
placement of the excavated CCR in an on -site lined CCR landfill. The excavation of CCR and the
closure of the Basin will be in accordance with applicable provisions of the North Carolina Coal
Ash Management Act of 2014, as amended (CAMA) (codified at N.C.G.S. § 130A-309.200 et
seq.), and the federal Disposal of Coal Combustion Residuals from Electric Utilities rule (CCR
Rule) (codified at 40 C.F.R. § 257.50 et seq.).
The MSS is owned and operated by Duke Energy in Catawba County on the west bank of Lake
Norman (Catawba River), near the town of Terrell, North Carolina. The MSS is a four -unit, 2,090
MW, coal-fired station. Units 1 and 2 began operation in 1965 and 1966, respectively, while units
3 and 4 began operation in 1969 and 1970, respectively.
Duke Energy has historically operated a single impoundment for storing wet sluiced coal ash
referred to as the Basin at the MSS. The Basin was constructed in conjunction with MSS
construction in 1965 and is impounded by an earthen dike (Basin Dam) located at the
southeastern end of the Basin, adjacent to Lake Norman. Based upon the CCR unit boundary,
the MSS Basin historically had a surface area of approximately 394 acres, and is now
approximately 360-acres, due to the construction of three permitted disposal facilities over areas
of the original Basin limits. Based on CCR inventory data provided by Duke Energy as of July
2019, the Basin is estimated to contain approximately 14 million cubic yards of CCR or an
estimated 16.8 million tons.
Closure activities for the Basin has have already begun with the initiation of decanting under the
Special Order by Consent (SOC). Upon approval of the Closure Plan by NCDEQ additional
actions will commence, including finalization of detailed designs, dewatering and removal of
interstitial water, contracting and detailed planning for the closure work, development of the new
lined landfill in conjunction with excavation of the CCR, final grading of the site, and development
of stormwater features and vegetative covers.
Figures ES-1 and ES-2 illustrate the current state, and post -closure state of the CCR Basins as
detailed by this Closure Plan.
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Duke Energy — Marshall Steam Station
CCR Surface Imaoundment CBE Closure Plan
Figure ES-1 Current View
December 18, 2019
Figure ES-2 Post Closure View
The Basin CCR will be removed to a new lined landfill on the plant property, located partially within
the prior footprint of the ash basin near Island Point Road. The landfill will rise approximately 200
feet above Island Point Road. Post -excavation, the Basin site will resemble the land's valley
shape before the basin was created. Soil will be graded to restore contours for stormwater flows,
then planted with native grasses for erosion control. The existing Basin dam will remain, with a
new stormwater pathway cut to a cove of Lake Norman. The stormwater outlet elevation will
impound stormwater over approximately 100 acres within the former Basin footprint. The existing
Structural Fill and Landfills will remain in place, with structural features added to ensure long-term
stability against adjacent areas of excavation.
The on -site CCR landfill represents a lateral and vertical expansion of the existing Industrial
Landfill (ILF) in accordance with North Carolina Solid Waste regulations.
This document also includes a description of the Post -Closure care plan, which provides a
description of the inspection, monitoring, and maintenance activities required to be performed
throughout the 30-year post -closure care period for the closed Basin at the MSS.
This document provides a summary of properties of the site, as well as geotechnical properties
of CCR and natural soils to support engineering analyses of the closure design. These analyses
indicate that the closure by excavation, as detailed in the Plan, meets regulatory requirements for
the stability of the site, management of surface water runoff, and access for effective maintenance
over the post closure care period.
In accordance with the requirements of N.C.G.S. § 130A-309.211(b)(1), Duke Energy separately
submitted an updated Corrective Action Plan (CAP) in parallel with this Closure Plan; the updated
CAP is herein incorporated in its entirety by this reference. Neither the updated CAP nor its
content is the work product of AECOM. Although the Closure Plan contains references to the
updated CAP, all specific relevant details to groundwater and related actions are found in the
updated CAP itself and not in this Closure Plan.
As detailed in the updated CAP, Duke Energy has begun to implement, and will continue
implementing, source control measures at the site, including (i) complete Basin decanting to lower
the hydraulic head within the Basin and decrease hydraulic gradients, reducing groundwater
seepage velocities and COI transport potential; and (ii) complete Basin closure, as well as closure
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of adjacent ash management areas. In addition, Duke Energy intends to implement a robust
groundwater remediation program that includes actively addressing COI in groundwater above
applicable standards at or beyond the compliance boundary using a combination of groundwater
extraction and clean water infiltration. The CAP provides that these corrective action measures
will most effectively achieve remediation of the groundwater through the use of groundwater
extraction wells along the Basin dam and to the east and north of the dam; and (ii) clean water
infiltration wells to the north of the Basin dam and east of the Basin. Significantly, groundwater
modeling simulations indicate (i) these measures will address COI at or beyond the compliance
boundary; and (ii) at such time the site -specific considerations detailed within the CAP have been
satisfied, including, but not limited to, securing all required state approvals, installing the
necessary equipment, and commencing full-scale system operation, COI at or beyond the
compliance boundary will meet the remedial objectives in nine years.
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1. INTRODUCTION
1.1 Background
The Marshall Steam Station (MSS) is located at 8320 NC Highway 150, in Catawba County, North
Carolina, and is a four -unit, 2,090 MW coal-fired station. Units 1 and 2 began operation in 1965
and 1966, respectively, while units 3 and 4 began operation in 1969 and 1970, respectively. CCR
has historically been managed in the MSS's on -site Basin. The MSS ceased all process water
and waste stream flows to the Basin in 2019
Figure 1-1 presents a site plan of the MSS.
The Basin is used to manage CCR at the MSS and includes a dam regulated by the NCDEQ and
Dam Safety:
1. The Basin Dam (NCDEQ ID: CATAW-054)
As further discussed in Section 2 below, the Closure method mandated by order of the NCDEQ
for the Basin is closure by excavation.
1.2 Closure Plan Objectives
The objective of this Closure Plan is to address the closure by excavation of CCR from the Basin
as directed by order of NCDEQ. Duke Energy does so without prejudice of its position that closure
by excavation is neither necessary nor appropriate for Basin. Duke Energy also notes that
approval from NCDEQ is required to proceed and develop the additional details as described
further within this Closure Plan to complete the necessary working documents to complete the
closure actions. Duke Energy submits this Closure Plan with the knowledge that other details will
follow, as necessary. This Closure Plan describes and communicates the key actions and
activities necessary to close the Basin in accordance with the requirements for written Closure
Plans for CCR surface impoundments presented in N.C.G.S. §130A-309.214(a)(4). Planned
closure activities include:
• Decanting the Basin;
• Construction and operation of a temporary water management system (WMS) to
manage all discharges in compliance with the NPDES permit during closure.;
• Dewatering to support safe excavation of CCR from the Basin;
• Excavation of the CCR and establishing post -excavation final grades using soil fill where
required;
• Construction of haul roads, and stormwater management systems,
• Construction of an on -site CCR landfill to permanently store the excavated CCR;
• Modification of the Basin spillways; and
• Restoration of disturbed areas.
1.3 Report Organization
This document is structured to follow the requirements provided in CAMA (G.S. §130A-
309.214(a)(4)).
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2. GOVERNING LAWS
In August 2014, the North Carolina General Assembly enacted CAMA, which contains specific
statutory requirements applicable to the CCR basins. Subsequently, in July 2016, the North
Carolina General Assembly enacted H.B. 630, Session Law 2016-95, which provides that
impoundments be classified as "low -risk" if, by certain deadlines, the owner has established
permanent alternative water supplies, as required, and has rectified any deficiencies identified by,
and has otherwise complied with requirements of, any dam safety order. NCDEQ determined
that Duke Energy met these criteria on November 14, 2018, and officially classified the Basin at
the MSS as "low -risk."
On April 1, 2019, NCDEQ issued its Closure Determination mandating that the Basin be closed
by excavation of the CCR pursuant to N.C.G.S. § 130A-309.214(a)(3)a. Aclosure plan is required
for each CCR surface impoundment regardless of the risk classification. CAMA's closure plan
requirements and cross-referenced sections of this Closure Plan are summarized in Table 2-1.
On April 26, 2019, Duke Energy filed a Petition for Contested Case Hearing before the North
Carolina Office of Administrative Hearings appealing this determination, on May 24, 2019 Duke
Energy filed amended petitions in the case. The petitions allege that in issuing its Closure
Determination, NCDEQ failed to (i) follow the mandatory process and procedure outlined in CAMA
and (ii) consider or apply the scientific and engineering evidence submitted and available to it in
reaching its decision to require the most expensive closure method available despite scientific
and engineering evidence demonstrating the availability of less expensive and more rapid closure
options that would continue to fully protect human health and the environment. Certain decisions
by the administrative law judge in that case are currently under appeal to the North Carolina
Superior Court.
In addition to the closure plan requirements, CAMA sets out groundwater assessment and
corrective action requirements. A Comprehensive Site Assessment report was submitted to
NCDEQ in September 2015, with supplemental reports submitted August 2016 and January 2018.
Duke Energy intends that an updated CAP will be submitted in parallel with this Closure Plan.
In addition to the above requirements, National Pollutant Discharge Elimination System (NPDES)
permit program compliance, SOC (which commits Duke Energy to initiate and complete decanting
of the Basins by dates certain) compliance, dam safety approvals for modifications to regulated
CCR basin dams, and environmental permitting requirements must be considered as part of
closure.
3. FACILITY DESCRIPTION AND EXISTING SITE FEATURES
3.1 Surface Impoundment Description
This section provides details on the CCR-related features at the MSS.
3.1.1 Site History and Operations
Figure 1-1 shows locations of the MSS plant, the Basin, and the Basin Dam, while Figure 3-1
also presents overall existing conditions including topography and bathymetry of the Basin. The
Basin is described in more detail below.
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Basin (CCR Unit): The Basin was constructed in 1965 and is located north of the MSS and
adjacent to Lake Norman. It is situated between topographic divides located along Sherrills Ford
Road to the west, Island Point Road to the north, and the Duke Energy property boundary to the
east. The natural topography at the site generally slopes downward from these divides to the
Basin and subsequently toward Lake Norman. The Basin consists of a single basin impoundment
behind an earthen dam located at the historical intersection of Holdsclaw Creek and the Catawba
River, on the southeastern end of the Basin. The Basin is dendritic in shape and is generally
located in a historical depression formed by Holdsclaw Creek and small tributaries to the creek.
The Basin includes coves of deposited CCR, interior dikes that impounded CCR in portions of the
Basin, and various areas of ponded water. The Basin waste boundary historically occupied an
area of approximately 394 acres, and the current CAMA CCR boundary occupies an area of
approximately 360 acres, due to the construction of three permitted disposal facilities (the ILF, the
Structural Fill and Phase II of the 1804 Landfill, further discussed below) over areas of the original
Basin limits. Water discharges through a weir box type principal spillway, located near the
northeastern abutment of the dam. The discharge flow is conveyed through a 36-inch diameter
high density polyethylene (HDPE) pipe into Lake Norman. This principal spillway, discharge
piping and outlet structure were constructed in 2016 as a replacement for the original principal
spillway riser, which was abandoned due to structural deficiencies under earthquake conditions.
The Basin water surface elevation is controlled through the use of stop logs located within the
inlet structure.
The CCR from the MSS coal combustion process, including flyash and bottom ash, has been
sluiced to the Basin since 1965. Flyash was collected primarily via dry handling starting in 1984.
Bottom ash sluiced to the Basin was periodically excavated. Flue Gas Desulfurization (FGD)
residue, which consists primarily of gypsum, has not been disposed in the Basin.
In early 2019, the Bottom Ash Handling Facility came on line to manage bottom ash generated at
the MSS. Once this facility became active, CCR was no longer sluiced to the Basin.
Contact stormwater and leachate from the FGD and Industrial Landfills as well as FGD
wastewater treatment system effluent was historically routed to the Basin. As of early 2019 these
flows have been redirected to the Lined Retention Basin for treatment prior to disposal.
Additional Facilities
The existing ILF was permitted pursuant to the authority of N.C.G.S. § 130A-295.4 (combustion
products landfills constructed partially or entirely within areas formerly used for the storage or
disposal of CCR) and in accordance with North Carolina's rules governing the siting, design, and
construction of sanitary landfills, and includes a double -liner system with a leak detection system
between the liners. It is Duke Energy's position that at such time the area of the former Basin
underlying the ILF were permitted under NCDEQ Permit No. 1812-INDUS-2008, they became an
intrinsic part of the landfill's base and ceased being "surface impoundment" under North Carolina
law. Accordingly, closure of the permitted ILF is not subject to CAMA's CCR surface impoundment
closure requirements and, thus, is not addressed under this Closure Plan. Instead, closure of the
permitted ILF will be conducted pursuant to a separate regulatory process in accordance with 15A
N.C.A.C. 13B § .0500.
The 1804 Landfill (Permit No. 1804-INDUS-1983) was subject to North Carolina's rules, 15A
N.C.A.C. 13B § .0500, governing the permitting of solid waste disposal sites in the state, and was
closed pursuant to those rules. As detailed in the documents developed as part of the permit
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process that culminated in NCDEQ's issuance of Permit No. 1804-INDUS-1983, the area
underlying the 1804 Landfill became an intrinsic part of its design and ceased being "surface
impoundment" at such time the unit was permitted by NCDEQ. Accordingly, the permitted 1804
Landfill is not subject to CAMA and, thus, is not addressed under this Closure Plan. However,
Duke Energy will undertake additional closure measures exceeding the standards set forth in 15A
N.C.A.C. 13B § .0500 as part of a separate regulatory process.
The Structural Fill was constructed and closed pursuant to 15A N.C.A.C. 13B § .1700
(Requirements for Beneficial Use of Coal Combustion By -Products), which sets out siting, design,
construction, operation, closure, and recordation requirements for such facilities. Permit No.
CCB0031 approved the utilization of coal combustion products to construct a structural fill on land
that was formerly an ash basin. As a result, the area underlying the fill became an intrinsic part
of its design and ceased being "surface impoundment" at such time NCDEQ approved
construction of the unit. Accordingly, the Structural Fill is not subject to CAMA and, therefore, is
not addressed under this Closure Plan. However, Duke Energy will undertake additional closure
measures exceeding the standards set forth in 15A N.C.A.C. 13B § .1700 as part of a separate
regulatory process.
3.1.2 Estimated Volume of CCR in Impoundments
Based on CCR Inventory Data provided by Duke Energy as of July 31, 2019, and upon a surface
comparison calculation, performed within AutoCAD Civil 3D, comparing the approximate pre -
development topography to the 2014 topographic and bathymetric survey, the approximate
volume of CCR in the Basin is listed in the table below. To compute the estimated mass of CCR
in place an assumed density of 1.2 tons per CY was used, which is the Duke Energy fleet wide
assumption. See Appendix A for the Estimated Volume of CCR in Impoundment calculation.
Impoundment
Estimated CCR Volume
Estimated CCR Weight
(CY)
(Tons)
Basin
14,030,000
16,836,000
* The Basin boundary used to estimate in -place CCR is based on the unit boundary as
prepared by SynTerra, but excluded the dam area.
3.1.3 Description of Surface Impoundment Structural Integrity
The purpose of this section is to summarize the CCR Basin's structural integrity evaluations
based on current existing information. This section includes the geotechnical, and hydrology
and hydraulics (H&H) capacity analyses results. In summary, the structural integrity of the CCR
impoundments and subsequent dam inspection reports meets the regulatory requirements of
EPA's CCR Rule (40 § CFR 257.73). Duke Energy's certifications of these requirements are
available on Duke Energy's publicly -accessible CCR Rule Compliance Data and Information
website.
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• Slope Stability
For the Basin Dam embankment, slope stability analysis results for the existing conditions global
factors of safety for static long-term maximum storage pool, static maximum surcharge pool,
sudden drawdown conditions, and pseudo -static seismic conditions meet regulatory and
programmatic criteria.
Liquefaction Conditions (where susceptible) and Liquefaction Potential
In 2016, AECOM performed liquefaction screening analyses for the Basin Dam embankment,
including a Probabilistic Seismic Hazard Analysis (PSHA) and Dynamic Response Analysis using
QUAD4M. Data from the PSHA and QUAD4M analyses indicate that the foundation and
embankment soils for the Basin Dam embankment meet liquefaction screening regulatory
requirements for minimum factor of safety. It is concluded that these soils are not subject to
liquefaction during the 2,500-year return period seismic event.
Hydrology and Hydraulics (H&H) Capacity Analyses
As part of the design of the new Principal Spillway in 2016, AECOM modeled the 6-hour 3/4
Probable Maximum Precipitation (PMP) using the most current bathymetric and topographic
survey information for the basin, dam crest, and auxiliary spillway. AECOM's analyses indicate
that the auxiliary spillway will not activate during the 500-year storm event and that the spillway
system can pass the SDF based on the 6-hour 3/4 PMP without overtopping.
Per direction from NCDEQ, additional hydrologic modeling was conducted to evaluate whether
the existing Basin and spillway system could convey the SDF generated during the full PMP event
without overtopping the dam. The PMP used for this analysis was developed and provided by
Applied Weather Associates (AWA) in July 2019. The evaluation involved incorporation of updated
drainage area characteristics, including upstream stormwater ponds under construction and other
storage areas. The evaluation showed that the Basin and existing spillway system could convey
the SDF generated during the full PMP without overtopping the dam.
3.1.4 Sources of Discharges into Surface Impoundments
Process flows no longer discharge to the Basin. Process flows are directed toward newly -
constructed lined retention basins. The MSS currently employs a dry ash handling system and
transports CCR to the on -site ILF.
Historically, wastewater or process water inputs to the Basin from the MSS included CCR sluice
water, equipment cooling wastewater, boiler and turbine sumps, sanitary wastes, and other low
volume wastes.
3.1.5 Existing Liner System
The Basin does not include a geomembrane or clay liner system and is considered to be unlined.
The Basin was constructed directly over the natural existing ground surface.
3.1.6 Inspection and Monitoring Summary
Weekly Basin inspections have been on -going since 2014, and include observation of upstream
slopes and shorelines, crest, downstream slopes, toes, abutment contacts and adjacent drainage
way(s), spillway(s) and associated structure(s), and other structures and features of the dam.
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Monthly inspections of the Basin include the weekly monitoring elements with the addition of
piezometer and observation well readings, water level gauges/sensors.
Daily inspections of the Basin are not routinely required, however, on a case -by -case basis, the
Basin may be inspected daily beginning at such times and continued for the duration as specified
by plant management. Such daily inspections might be initiated during a repair activity on the dam
or in response to a specific imposed regulatory agency requirement.
The Basin is inspected annually by an independent third -party consultant. In a letter dated August
13, 2014, NCDEQ requires these inspections to be conducted annually at all of Duke Energy's
CCR impoundments in North Carolina. These inspections are intended to confirm adequacy of
the design, operation, and maintenance of the surface impoundments in accordance with
accepted engineering standards. Reports are to be submitted to the NCDEQ within 30 days of
the completion of the inspection.
The results of the annual inspections are used to identify needed repairs, repair schedules, to
assess the safety and operational adequacy of the dam, and to assess compliance activities
regarding applicable permits, environmental and dam regulations. Annual inspections are also
performed to evaluate previous repairs. The annual inspections of the dikes have been ongoing
since 2009, with 5-year inspections conducted between 1979 and 2009.
The 2015 through 2019 annual inspections did not identify features or conditions in the Basin
Dams, or their outlet structures or spillways that indicate an imminent threat of impending failure
hazard. Review of critical analyses indicated the design conforms to current engineering state of
practice to a degree that no immediate actions are required other than the recent and ongoing
surveillance and monitoring activities already underway.
Special, episodic inspections of the Basin may be performed during episodes of earthquake,
emergency, or other extraordinary events. Visual inspections are performed after a heavy
precipitation event when accumulation of four inches of rainfall or greater occurs within a 24-hour
period. An internal inspection will be performed if an earthquake is felt locally or detected by the
US Geological Survey measuring greater than a Magnitude 3 and with an epicenter within 50
miles of the dams. A special inspection would also be performed during an emergency, such as
when a potential dam breach condition might be identified or when construction activities (e.g.,
basin cleanout) are planned on or near the dams. Special inspections are also conducted when
the ongoing surveillance program identifies a condition or a trend that warrants special evaluation.
3.2 Site Maps
3.2.1 Existing CCR Impoundment Related Structures
A site map showing property boundary, location of the MSS, Basin with its boundaries and
topographic and bathymetric contours are shown on Figure 3-1.
3.2.2 Receptor Survey
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated
by this reference but its content is not the work product of AECOM.
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3.2.3 Existing On -Site Landfills
The existing on -site landfills at the MSS are presented in the table below and are shown on the
attached Figures 1-1 and 3-1.
Unit
Permit Number
Comment
Closed prior to the CCR
Phase I of 1804 Landfill
1804-INDUS
Rule
Closed prior to the CCR
Phase II of 1804 Landfill
1804-INDUS
Rule
Asbestos Landfill
1804-INDUS
Non CCR, Closed
Demolition Landfill
1804-INDUS
Non CCR, Closed
Closed prior to the CCR
Structural Fill
CCB0031
Rule
Closed prior to the CCR
Structural Fill Access Road
CCB0030
Rule
Industrial Landfill
1812-INDUS
CCR Rule, Active
Closed prior to the CCR
Structural Fill Beneath Industrial Landfill
CCB0072
Rule
Closed prior to the CCR
FGD Landfill
1809-INDUS
Rule
3.3 Monitoring and Sampling Location Plan
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated by
this reference but its content is not the work product of AECOM.
Locations of the existing groundwater monitoring wells are shown in the Closure Plan Drawings,
Appendix D, but the CAP should be consulted for details of well locations, names, and status.
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4. RESULTS OF HYDROGEOLOGIC, GEOLOGIC, AND GEOTECHNICAL INVESTIGATIONS
4.1 Background
An overall boring and existing monitoring well location plan indicating the locations of recent and
historical borings, monitoring wells, piezometers and Cone Penetration Test locations are shown
on Drawing MAR_C999.002.009 included in Appendix D.
This section summarizes the site geology and hydrogeology; site stratigraphy of the geologic units
underlying the surface impoundments; as well as geotechnical properties of the CCR and the
uppermost stratigraphic unit under the surface impoundment. Descriptions of the geotechnical
and hydrogeological explorations, data and results are focused on those conducted on or adjacent
to the Basin, including the Basin Dam.
4.2 Hydrogeology and Geologic Descriptions
Hydrological and geologic descriptions, including descriptions of regional geology, site specific
geology, and regional and site hydrogeology are included as part of the CAP being prepared
separately by SynTerra for Duke Energy and is being submitted in parallel to this Closure Plan.
The CAP is herein incorporated by this reference but its content is not the work product of
AECOM.
4.3 Stratigraphy of the Geologic Units Underlying Surface Impoundments
Descriptions of geologic units underlying the Basin are included as part of the CAP being prepared
separately by SynTerra for Duke Energy and is being submitted in parallel to this Closure Plan.
The CAP is herein incorporated by this reference but its content is not the work product of
AECOM.
4.4 Geotechnical Properties
This section provides a summary of geotechnical conditions and properties found from
investigations performed within the Basin and Basin Dam areas. The presented information was
obtained from previous geotechnical investigations at the site and recent investigation activities
conducted to support the Closure Plan development. The geotechnical conditions within the Basin
generally consist of CCR (interbedded layers of fly ash and bottom ash) placed in the basin
primarily by hydraulic sluicing underlain by residual soil, saprolite, partially weather rock (PWR),
and bedrock.
For the purposes of discussion of the geotechnical properties of the materials, the saprolite
material is described as residual material. General properties of the various materials
encountered within and surrounding the Basin are described below. A range of measured material
properties of laboratory tests performed by AECOM, SynTerra, and others for the subsurface
explorations completed within the Basin is presented on Table 4-1. A summary of laboratory
tests data performed at the MSS in support of the closure design is presented in Appendix B.
4.4.1 CCR Within Basin
• Sluiced CCR (Fill): Sluiced CCR was encountered within the Basin in multiple borings
completed by AECOM, HDR, SynTerra and S&ME. The CCR was classified as moist to wet,
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gray and dark gray to black, bottom ash as silty sand (SM) or fly ash as sandy silt (ML). The
thickness of the sluiced CCR ranged from 4 to 85 ft. The uncorrected N-values recorded in
the sluiced CCR ranged from WOH to 7 bpf, but much of the material was 1 bpf or less.
4.4.2 Liner Material Properties
The Basin is unlined so there are no associated material properties.
4.4.3 Subsurface Soil Properties
• Compacted Fill: Soil fill, and in some cases bottom ash, fill was encountered at the ground
surface in multiple borings completed by AECOM, HDR, SynTerra and S&ME. Fill materials
are associated with saddle dikes constructed at the time the Basin was being developed (SB-
102, P-5/B-2, STB-14), FGD Wetlands treatment area (SB-103, AB-21S/D), roadway
embankments (B-4), and ILF construction (AB-15S/SL/D/BR, P-6).
The soil fill varies and generally consists of loose to medium dense, moist to wet, reddish
brown to grayish brown, sandy silt (ML), silty sand (SM), or sand with silt (SW-SM). CCR
used as fill is generally classified as bottom ash (SM). The fill thickness ranged from 4 to
53.5-ft. The uncorrected N-values recorded in the fill ranged from 1 to 22 bpf.
• Alluvium: Alluvial soils were encountered beneath the sluiced or stacked CCR or beneath
embankment fill material in several borings in the vicinity of the Basin. The alluvium deposits
consisted of very loose, moist, sandy silt (ML) to wet, gray or brown, silty sand (SM). The
thickness of this layer ranged from 4 to 10 ft. The uncorrected N-values recorded in the
alluvium ranged from WOH to 11 bpf.
• Residuum: Residual soils encountered in numerous borings beneath sluiced or stacked CCR,
beneath embankmentfill material and beneath alluvial soils, where encountered. The residual
soils vary widely and classify as moist to wet, brown to brownish yellow, sandy silt (ML) or
sand with silt (SW-SM) with varying quantities of quartz and mica. Occasionally, soils in this
deposit were classified as elastic silt (MH), silty sand (SM), sand with clay (SW -SC), sand
(SW), clayey sand (SC), lean clay (CL) and fat clay (CH). The thickness of this layer ranged
from 5 to 42-ft and uncorrected N-values recorded in the residuum ranged from 3 to 72 bpf.
• Partially Weathered Rock (PWR): PWR was encountered in numerous borings underlying
residual soils. PWR is classified as dark yellowish brown, sand (SW) or sand with silt and
gravel (SW-SM). When classified as bedrock, the PWR primarily consisted of meta -quartz
diorite and quartz biotite schist. The thickness of the PWR ranged from less than 1-ft to 22-ft.
The PWR is very stiff and resulted in refusal to advance of soil drilling tools in several borings.
• Bedrock: Bedrock was encountered beneath PWR and was sampled by coring at nine
locations by AECOM and HDR. The bedrock encountered consisted of black and white to
dark gray, medium to very strong, thinly foliated Biotite Gneiss or Amphibolite gneiss bedrock.
Meta -quartz diorite and biotite schist bedrock was occasionally encountered as well.
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Percent core recovery varied from 4 to 100%, with an average of 94%. RQD varied from 0 to
100% with an average RQD of 88%.
4.4.4 Basin Dam Soil Properties
• Embankment Compacted Fill: The compacted fill materials used to construct the Basin Dam
generally consist of stiff sandy silt (ML), varying to medium to dense moist, silty sand (SM).
Although the embankment soils were relatively homogeneous, isolated intervals of limited
thickness were classified as elastic silt (MH). The compacted fill extends from the current crest
elevation (approximately El. 800 ft.) to approximate El. 710 ft., resulting in a maximum
embankment height of approximately 90 feet.
• Dumped Fill Berm: The berms constructed on the upstream and downstream sides of the
Basin Dam embankment are referred to in the design drawings as being constructed using
"Dumped Fill". This reference apparently reflects the compactive effort used during
construction. This layer was placed after construction of the Embankment Compacted Fill.
The dumped fill berm downstream of the embankment dam exists from the southern end of
the dam to just north of the former principal spillway. The dumped fill berm materials
downstream of the Basin Dam generally consist of loose to dense, moist to wet, silty sand
(SM) with lesser amounts of soft to stiff sandy silt (ML). The dumped fill materials were
relatively heterogeneous in nature and materials encountered included rip -rap, shot rock,
concrete debris and limited amounts of organics. The dumped fill extends from the current
bench elevation (from El. 780 to El. 772 ft) to approximately El. 712 ft., resulting in a maximum
embankment height of approximately 60 ft.
4.5 Chemical Analyses of Impoundment Water, CCR and CCR Affected Soil
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated
by this reference, but its content is not the work product of AECOM.
4.6 Historical Groundwater Sampling Results
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated
by this reference but its content is not the work product of AECOM.
4.7 Groundwater Potentiometric Contour Maps
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated
by this reference but its content is not the work product of AECOM.
4.8 Estimated Vertical & Horizontal Extent of CCR within the Impoundments
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated
by this reference but its content is not the work product of AECOM.
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5. GROUNDWATER MODELING ANALYSES
In accordance with the requirements of N.C.G.S. § 130A-309.21 1 (b)(1), Duke Energy
separately submitted an updated Corrective Action Plan (CAP) in parallel with this Closure Plan;
the updated CAP is herein incorporated in its entirety by this reference. Neither the updated
CAP nor its content is the work product of AECOM. Although the Closure Plan contains
references to the updated CAP, all specific relevant details to groundwater and related actions
are found in the updated CAP itself and not in this Closure Plan.
The updated CAP evaluates the extent of, and remedies for, constituents of interest (COI) in
groundwater associated with the Basin and certain adjacent additional source areas, focusing
on constituent concentrations detected above the applicable 02L Standards, Interim Maximum
Allowable Concentrations, or approved background threshold values at or beyond the
compliance boundary to the north and east of the Basin. In addition, the updated CAP considers
the federal groundwater corrective action requirements at 40 C.F.R. §§ 257.96-.98.
As detailed in the updated CAP, Duke Energy has begun to implement, and will continue
implementing, source control measures at the site, including (i) complete Basin decanting to
lower the hydraulic head within the Basin and decrease hydraulic gradients, reducing
groundwater seepage velocities and COI transport potential; and (ii) complete Basin closure, as
well as closure of adjacent ash management areas. In addition, Duke Energy intends to
implement a robust groundwater remediation program that includes actively addressing COI in
groundwater above applicable standards at or beyond the compliance boundary using a
combination of groundwater extraction and clean water infiltration. The CAP provides that these
corrective action measures will most effectively achieve remediation of the groundwater through
the use of groundwater extraction wells along the Basin dam and to the east and north of the
dam; and (ii) clean water infiltration wells to the north of the Basin dam and east of the Basin.
Significantly, groundwater modeling simulations indicate (i) these measures will address COI at
or beyond the compliance boundary; and (ii) at such time the site -specific considerations
detailed within the CAP have been satisfied, including, but not limited to, securing all required
state approvals, installing the necessary equipment, and commencing full-scale system
operation, COI at or beyond the compliance boundary will meet the remedial objectives in nine
years.
5.1 Site Conceptual Model Predictions
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated by
this reference but its content is not the work product of AECOM.
5.2 Groundwater Chemistry Effects
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated by
this reference but its content is not the work product of AECOM.
5.3 Groundwater Trend Analysis Methods
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated
by this reference but its content is not the work product of AECOM.
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6. BENEFICIAL AND FUTURE USE
6.1 CCR Use
At this time, Duke Energy has not identified a beneficial use of CCR from the Basin at the MSS.
6.2 Site Future Use
At this time Duke Energy has not identified any future use of the land reclaimed by the dewatering
and excavation of the Basin, except for the proposed expansion of the ILF, which is proposed to
be partially built within the northern footprint of the excavated Basin.
7. CLOSURE DESIGN DOCUMENTS
7.1 Engineering Evaluations and Analyses
Engineering evaluations and analyses to support closure of the Basin at the MSS, as detailed in
this Closure Plan, are provided in Appendix C.
After approval of this Closure Plan by NCDEQ and based on additional information about
constructability, geotechnical slope stability calculations will be performed to support interim
excavation stability requirements and permanent closure conditions. Geotechnical calculations
for the proposed CCR landfill design will be performed separately as part of its permit application,
which will follow NCDEQ approval of this Closure Plan. Dam modification related calculations will
be included in the dam modification permit applications, which will follow NCDEQ approval of this
Closure Plan.
Safe and effective access to the Basin is critical to CCR excavation and the completion of closure.
Access road locations into or across the Basin cannot be reliably established until detailed
phasing of closure is developed, and a contractor is selected to complete the work. A variety of
mitigation techniques can be applied, such as installation of a geogrid and crushed stone
aggregate, placement and spreading of dry CCR over the Basin surface to establish access, and
use of low ground pressure or light weight construction equipment.
Areas for stockpiling or conditioning of CCR are generally needed. These areas must be
established within the limits of the Basin and require placement or stacking of CCR excavated
from other areas of the Basin. They can be established in areas where all or most of the CCR
has been excavated, or on areas where a significant depth of CCR remains in place. Sluiced
CCR forming the foundation of stockpiles or conditioning areas may be subject to bearing capacity
or slope failures from the additional vertical compressive stress imparted by the stacked CCR and
hauling equipment. Excavated slopes in sluiced CCR adjacent to or forming access roads,
stockpiles or conditioning areas are subject to the same analyses outlined below for interim CCR
excavation slopes.
During excavation of CCR, interim or temporary excavated CCR slopes are commonly created.
These slopes vary in height and the duration they will have to stand. Some slopes are subject to
potential loading from hauling or stockpiling operations. The location and geometry of such slopes
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cannot be established during design. These elements depend on the means and methods
employed by the construction contractor, potentiometric surfaces, schedule, and other site
conditions. Geotechnical analyses will be completed and performance criteria related to the
allowable height, slope and preparation (dewatering, etc.) for temporary or interim CCR slopes
will be established prior to commencement of construction.
Dewatering is necessary to remove the interstitial (pore) water from the CCR to facilitate
excavation, to access in -place CCR or to establish safe slopes prior to and after CCR excavation.
It is anticipated that performance criteria will be established to identify required vertical and
horizontal limits of interstitial water removal at critical locations and for critical conditions during
closure.
Excavation in a deep valley fill creates significant safety risks that need further evaluation and will
require the means and methods input from a contractor to fully address before closure excavation
work commences. A detailed phasing and excavation plan will be developed after this Closure
Plan is approved by NCDEQ.
7.2 Closure Plan Activities
The primary activities associated with closure by excavation are as follows:
• Lower free water level through the riser outlet by removing stoplogs under the existing
NPDES permit (completed).
• Decant the Basin by using floating pumps, screened intakes, and pumping through the
discharge to the existing NPDES-permitted Outfall 002 or to the WMS (ongoing).
• Construction and operation of a temporary water management system to manage all
discharges in compliance with the NPDES permit during closure.
• Dewater the CCR to allow for safe access. CCR excavation and conditioning prior to
placement in the ILF.
• Start CCR excavation from the Basin, with sequencing determined for optimal
progression. Manage and control of dust -generating activities through specific site
planning and mitigation. Construct landfill cells in coordination with CCR excavation.
Place the excavated CCR in the ILF, and compact. Instrumentation and monitoring
requirements to be developed prior to construction will be followed to verify construction
phase stability. Construction dewatering to be used as needed to provide stable work
areas and slopes.
• Maintain required hydraulic storage capacity through the excavation process and
progressively install the primary stormwater outlet as excavation advances
• Complete closure by excavation verification. Grade the area to promote positive drainage
and seed for vegetative growth.
Additional information and details pertaining to this Closure Plan for the MSS Basin are provided
in the Closure Plan Drawings, which can be found in Appendix D.
7.3 Closure Plan Drawings
The Closure Plan drawings found in Appendix D include the following:
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• Cover Sheet
• General Notes
• Existing Conditions Plan with Aerial Photograph
• Existing Conditions Plan(s) with Topography
• Exploration Location Plan(s)
• Demolition Plan(s)
• Estimated Bottom of CCR Plan(s)
• Final Closure Grading Plan(s)
• Final Closure Grading Profile, Cross -Sections, and Details
• On -Site Landfill Schematic Plan(s)
• On -Site Landfill Schematic Cross -Sections
December 18, 2019
These Closure Plan drawings will be further developed and refined to develop construction level
drawings during subsequent stages following NCDEQ approval of the Closure Plan. In addition,
supplemental drawing sets will be prepared on an as needed basis to support dam modification
permits, erosion and sediment control permits, NPDES permit modifications, and other related
permits.
Once the excavation grades shown on the Closure Plan drawings have been achieved, the
procedures in the Duke Energy Excavation Soil Sampling Plan (Appendix E) will be followed to
confirm that the closure by excavation has been achieved.
7.4 Description of the Construction Quality Assurance Plan
A Construction Quality Assurance (CQA) Plan will be developed following NCDEQ approval of
the Closure Plan for closure of the Basins at the MSS. The CQA Plan will be prepared to address
N.C.G.S. §130A-309.214(a)(4)(g). Its purpose is to provide a description of the CQA program to
be adhered to in execution of closure activities. The CQA Plan will present a description of the
roles and responsibilities for monitoring and testing activities and provides guidance on the
methodology to be used for evaluating whether the construction has been performed in
accordance with the approved Closure Plan. The CQA Plan will also detail the material properties
and specifications; methods for transportation, handling, and storage of materials; test methods
and verifications; manufacturer, field and laboratory testing; field activities for construction
monitoring and oversight; and reporting and documentation requirements. Technical
specifications to be developed as part of the construction -level design packages for contractor
bidding will present specific material properties and specifications.
The CQA Plan will address materials and CQA activities associated with the following
components:
• Earthwork
• CCR Excavation
• Structural Soil Fill
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HDPE Piping
As -Built Conditions
Record Documentation Report
8. MANAGEMENT OF WASTEWATER AND STORMWATER
A Temporary Stormwater Pond was constructed as a part of the Structural Fill Stormwater
Redirect Project to divert stormwater flows from beneath the Structural Fill, from the ILF, and from
areas tributary to the northern most fingers of the Basin that formerly drained to the Basin. This
diverted stormwater is now collected in the Temporary Stormwater Pond and pumped to a newly
established NPDES Stormwater Outfall (SW025), located east of Phase II of the 1804 Landfill,
which is tributary to a finger of Lake Norman northeast of the Basin. Additional temporary
diversions of surface water may also be provided in certain areas and within the Basin (as needed)
during CCR excavation.
The MSS manages wastewater and stormwater under two NPDES permits issued by the NCDEQ.
Permit number NC0004987, issued May 5, 2015 (NCDEQ, 2015a) and modified April 2, 2018
(NCDEQ, 2018a) addresses the discharge of various process -related wastewaters in accordance
with specified limits and monitoring requirements. Permit number NCS000548, issued May 15,
2015 (NCDEQ, 2015b), and modified January 24, 2017 and September 20, 2018, provides
monitoring and best management practice requirements for industrial stormwater discharges from
the MSS. The limits and requirements stipulated in the aforementioned permits can be found in
the permit documents discussed above. Discharges to surface waters and treated process -
related wastewaters flow directly or indirectly to Lake Norman, but as April 11, 2019, no process
flows are discharged to the Basin.
The Basin discharge will continue to be in service during closure to meet the NPDES permit
discharge requirements as it goes through the phases of decanting and dewatering. With
decanting underway discharges from the Basin via the existing passive gravity discharge system
have stopped. Decanting is proceeding via mechanical pumping. The pumping system is
expected to draw down the stored water after storm events, route through the water management
process if necessary, and discharge via the permitted outfall. When dewatering of the CCR
begins, all discharge flows are anticipated to be routed though the water management process in
order to meet the permitted discharge limits.
The Basin currently has the capacity to contain the PMP storm event by maintaining the water
surface level elevation at or below El. 788.20 ft, which provides a minimum freeboard of 0.94 ft.
As part of the closure, the discharge riser structure from the abandoned principal spillway and the
existing Principal Spillway will be removed. The post -closure grades will include several
stormwater channels within the fingers of the Basin that convey stormwater from the outer edges
of the watershed to a permanent stormwater pond located within the southern half of the Basin.
A new surface water outlet structure will be constructed northeast of the Basin Dam in the vicinity
of the existing Auxiliary Spillway. The stormwater pond will then discharge through the new
surface water outlet structure, and flow into Lake Norman through a newly established NPDES
Stormwater Outfall. Under this post closure condition, there will be increased flow into Lake
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Norman compared with existing conditions, and energy dissipation will be provided at the outlet
point to minimize erosion of the Lake Norman bank.
Wastewater from the Basin will be pumped, treated and discharged in two phases; the Decanting
phase and Dewatering phase. In the Decanting phase, free water above the settled CCR layer
will be removed from the Basin without the mechanical disturbance of the ash. The MSS water
management process has a designed flow rate of 1750 GPM. Following the decanting phase and
as the Closure schedule dictates, the MSS will advance into the dewatering phase to remove
interstitial water from the Basin. During this phase, additional physical -chemical treatment
processes will be added to the WMS as necessary to maintain compliance with the requirements
of the discharge permit. During the Dewatering phase, the MSS WMS will have a designed flow
rate of 400-500 GPM.
Dewatering is performed to remove the interstitial or pore water from the CCR to facilitate
excavation, to access in -place CCR or to establish safe slopes prior to and after CCR excavation.
It is anticipated that performance criteria will be established in the construction -level
documentation to identify required vertical and horizontal limits of interstitial water removal at
critical locations and for critical conditions during closure.
Appendix C1 presents the results of the Post -Closure Stormwater Management calculations
8.1 Anticipated Changes in Wastewater and Stormwater Management
Closure of the Basin has necessitated changes in the management of a number wastewater and
process streams. Wastewater and process streams previously discharging to the Basin have
been rerouted to new lined retention basins as separate treatment systems.
A temporary WMS will be utilized such that the NPDES Outfall 002 effluent discharge limits will
be met throughout the duration of decanting/dewatering and closure.
Duke Energy will obtain necessary permit coverage for any flows associated with post closure
cap in place conditions as plans are finalized (e.g. groundwater remediation, cap underdrains,
etc.). A water management process will be utilized such that the permit terms can be met
throughout the duration of dewatering, closure and post -closure timeframes.
Erosion and Sediment Control Plans for different phases of the construction will be developed as
part of the construction -level packages and formal erosion and sediment control plan permit
submittal. The details for the erosion and sediment control measures depicted on the drawings in
this Closure Plan submittal will be re-evaluated after the specific construction phasing is
established, which will follow NCDEQ approval of this Closure Plan. In addition, erosion and
sediment control measures may be installed and removed in phases as stabilization is achieved.
8.2 Wastewater and Stormwater Permitting Requirements
Additional information on required permits is described in Section 10.
9. DESCRIPTION OF FINAL DISPOSITION OF CCR
CCR will be dispositioned by placement into an approved and permitted lined CCR landfill. Duke
Energy intends to expand/construct a new on -site Landfill to accept CCR in completion of the
NCDEQ mandated closure by excavation. Duke Energy intends to construct a new on -site Landfill
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to accommodate CCR dispositioned in completion of the NCDEQ mandated closure by
excavation. A permit application for construction of the on -site landfill will be prepared and
submitted to NCDEQ Division of Waste Management following approval of this Closure Plan.
Vegetation encountered or removed during the progression of the work will be managed in
accordance with state regulations for handling and disposal.
10. APPLICABLE PERMITS FOR CLOSURE
Refer to Table 10-1 for detailed information on the potential and applicable permitting/approval
needed to implement this Closure Plan.
Development of permitting package submittals and/or regulatory approval requests would follow
NCDEQ approval of the Closure Plan.
11. DESCRIPTION OF POST -CLOSURE MONITORING AND CARE
A post -closure plan will be developed following NCDEQ approval of the Closure Plan for closure
of the Basin. The purpose of the post -closure plan will be to provide a description of the inspection,
monitoring, and maintenance activities required to be performed throughout the 30-year post -
closure care period for the closed Basin
The post -closure plan will be developed to meet the requirements of CAMA (G.S. §130A-
309.214(a)(4)(k)). The items that will be in the post -closure plan for the MSS include:
• Name, address, phone number, and email address of the responsible office or person;
• Means and methods of managing affected groundwater and stormwater;
• Maintenance of the groundwater monitoring systems;
• Regular inspection and maintenance;
• Groundwater and surface water monitoring and assessment program (included as part of
the CAP);
• Description of planned post -closure uses; and
• Financial assurance estimates for post -closure operations and maintenance and remedial
action.
11.1 Groundwater Monitoring Program
This information is included as part of the CAP being prepared separately by SynTerra for Duke
Energy and is being submitted in parallel to this Closure Plan. The CAP is herein incorporated by
this reference but its content is not the work product of AECOM.
A=COM MARSHALL CCR SURFACE IMPOUNDMENT CBE CLOSURE PLAN 17

AECOM December 18, 2019
Duke Energy — Marshall Steam Station
CCR Surface Imaoundment CBE Closure Plan
12. PROJECT MILESTONES AND COST ESTIMATES
12.1 Project Schedule
A Closure project schedule has been prepared by Duke Energy and is provided below. The
schedule defines the following anticipated activities and milestones:
• Engineering, decanting, dewatering Ongoing
• Submit plan and design for landfill construction permit Q4-2020
• Start CCR excavation using existing landfill airspace Q1-2021
• Landfill Permit Approval Q4-2021
• Start new landfill construction Q4-2021
• Complete CCR excavation Q4-2034
• Complete final closure and cover system of new landfill Q4-2035
Lailed
Site final grading and vegetative cover Q4-2036
A construction schedule will be developed following NCDEQ approval of this Closure
Plan.
12.2 Closure and Post -Closure Cost Estimate
Cost estimates for closure and post -closure of the Basin at MSS were developed by Duke Energy
and provided to AECOM. These cost estimates are not a work product of AECOM. These are
Class 5 estimates as the detailed and final design is not developed at this stage of the closure
project. Following approval of this Closure Plan by NCDEQ and further development of the project
plans and engineering designs the cost estimate will be refined and updated.
The cost to complete the closure by excavation, including the new CCR landfill, is estimated to
be $674 million.
The cost to perform the 30-year post -closure activities and monitoring is estimated as to be $165
million.
The cost estimates prepared by Duke Energy includes the following major activities:
• Mobilization and Site Preparation
• Dewatering, earthwork, and subgrade preparation
• CCR excavation
• Stormwater management, erosion and sediment control, and site restoration
• Engineering support (design and CQA)
• Post closure — groundwater monitoring
• Post closure — operations and maintenance
• Contingency
A=COM MARSHALL CCR SURFACE IMPOUNDMENT CBE CLOSURE PLAN 18

AECOM
Duke Energy — Marshall Steam Station
CCR Surface Impoundment CBE Closure Plan
December 18, 2019
Corrective action costs are included as part of the CAP being prepared separately by SynTerra
for Duke Energy and are being submitted in parallel to this Closure Plan. The CAP is herein
incorporated by this reference, but its content is not the work product of AECOM.
�L=Com MARSHALL CCR SURFACE IMPOUNDMENT CBE CLOSURE PLAN 19

AECOM December 18, 2019
Duke Energy — Marshall Steam Station
CCR Surface Impoundment CBE Closure Plan
13. REFERENCED DOCUMENTS
ESP Associates, P.A. (ESP). (2012a). Hydrologic Analysis, Marshall Steam Station, Catawba
County, North Carolina, July 6, 2012.
ESP Associates, P.A. (ESP). (2012b). Dam Breach Analysis, Marshall Steam Station, Catawba
County, North Carolina, October 10, 2012.
North Carolina Department of Environmental Quality (NCDEQ). (2015a). Draft Permit to
Discharge Wastewater under the NPDES, Duke Energy Marshall Steam Station, Permit
No. NC0004987, May 5, 2015.
North Carolina Department of Environmental Quality (NCDEQ). (2015b). Permit to Discharge
Stormwater under the NPDES, Duke Energy Marshall Steam Station, Permit No.
NCS000548, May 15, 2015.
North Carolina Department of Environmental Quality (NCDEQ). (2018a). SPECIAL ORDER BY
CONSENT SOC No. S17-009, Duke Energy Carolinas LLC Allen Steam Station,
Marshall Steam Station, & Rodgers Energy Complex NDPES Permits NC0004979,
NC0004987 & NC0005088 Gaston, Catawba & Rutherford Counties April 25, 2018
A=COM MARSHALL CCR SURFACE IMPOUNDMENT CBE CLOSURE PLAN 20

AECOM December 18, 2019
Duke Energy — Marshall Steam Station
CCR Surface Impoundment CBE Closure Plan
PROFESSIONAL ENGINEER CERTIFICATION
I, John Angelo Bove, being a registered Professional Engineer in the state of North Carolina, do
hereby certify to the best of my knowledge, information, and belief, that the information
contained in this Closure Plan dated December 18, 2019, was developed pursuant to the
requirements of N.C.G.S. § 130A-309-214(a)(4) and has been prepared pursuant to recognized
and generally accepted good engineering practices.
SIGNATURE
DATE December 18, 2019
A=COM MARSHALL CCR SURFACE IMPOUNDMENT CBE CLOSURE PLAN 21

TABLES

AECOM Table 2-1: NC CAMA Closure Plan Requirements November 6, 2019
Summary and Cross Reference Table
Duke Energy, Marshall Steam Station
No.
Description
Corresponding Closure
Plan Section
Part II. Provisions for Comprehensive Management of Coal Combustion Residuals
§ 130A-309.214(a)(4) Closure Plans for all impoundments shall include all of the following:
a. Facility and coal combustion residuals surface impoundment description. — A description of the operation of the site that shall include, at a minimum, all of the following:
1
Site history and history of site operations, including details on the manner in which coal combustion residuals have been stored and disposed of historically.
3.1.1
2
Estimated volume of material contained in the impoundment.
3.1.2
3
Analysis of the structural integrity of dikes or dams associated with impoundment.
3.1.3
4
All sources of discharge into the impoundment, including volume and characteristics of each discharge.
3.1.4
5
Whether the impoundment is lined, and, if so, the composition thereof.
7.1
6
A summary of all information available concerning the impoundment as a result of inspections and monitoring conducted pursuant to this Part and otherwise available.
3.1.6
b. Site maps, which, at a minimum, illustrate all of the following:
1
All structures associated with the operation of any coal combustion residuals surface impoundment located on the site. For purposes of this sub -subdivision, the term "site" means the land or waters within the property boundary of the
applicable electric generating station.
3.2.1
2
All current and former coal combustion residuals disposal and storage areas on the site, including details concerning coal combustion residuals produced historically by the electric generating station and disposed of through transfer to
structural fills.
3.3
3
The property boundary for the applicable site, including established compliance boundaries within the site.
3.3
4
All potential receptors within 2,640 feet from established compliance boundaries.
3.2.2
5
Topographic contour intervals of the site shall be selected to enable an accurate representation of site features and terrain and in most cases should be less than 20-foot intervals.
3.3
6
Locations of all sanitary landfills permitted pursuant to this Article on the site that are actively receiving waste or are closed, as well as the established compliance boundaries and components of associated groundwater and surface water
monitoring systems.
3.2.3
7
All existing and proposed groundwater monitoring wells associated with any coal combustion residuals surface impoundment on the site.
3.3
8
JAII existing and proposed surface water sample collection locations associated with any coal combustion residuals surface impoundment on the site.
3.3
c. The results of a hydrogeologic, geologic, and geotechnical investigation of the site, including, at a minimum, all of the following:
1
A description of the hydrogeology and geology of the site.
4.1
2
A description of the stratigraphy of the geologic units underlying each coal combustion residuals surface impoundment located on the site.
4.2
3
The saturated hydraulic conductivity for (i) the coal combustion residuals within any coal combustion residuals surface impoundment located on the site and (ii) the saturated hydraulic conductivity of any existing liner installed at an
impoundment, if any.
4.3
4
The geotechnical properties for (i) the coal combustion residuals within any coal combustion residuals surface impoundment located on the site, (ii) the geotechnical properties of any existing liner installed at an impoundment, if any, and
(iii) the uppermost identified stratigraphic unit underlying the impoundment, including the soil classification based upon the Unified Soil Classification System, in -place moisture content, particle size distribution, Atterberg limits, specific
gravity, effective friction angle, maximum dry density, optimum moisture content, and permeability.
4.4
5
A chemical analysis of the coal combustion residuals surface impoundment, including water, coal combustion residuals, and coal combustion residuals -affected soil.
4.5
6
Identification of all substances with concentrations determined to be in excess of the groundwater quality standards for the substance established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code,
including all laboratory results for these analyses.
4.6
7
Summary tables of historical records of groundwater sampling results.
4.6
8
A map that illustrates the potentiometric contours and flow directions for all identified aquifers underlying impoundments (shallow, intermediate, and deep) and the horizontal extent of areas where groundwater quality standards
established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code for a substance are exceeded.
4.7
9
Cross -sections that illustrate the following: the vertical and horizontal extent of the coal combustion residuals within an impoundment; stratigraphy of the geologic units underlying an impoundment; and the vertical extent of areas where
groundwater quality standards established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code for a substance are exceeded.
4.8
1 OF 3

AECOM Table 2-1: NC CAMA Closure Plan Requirements November 6, 2019
Summary and Cross Reference Table
Duke Energy, Marshall Steam Station
Corresponding Closure
No.
Description
Plan Section
d.
The results of groundwater modeling of the site that shall include, at a minimum, all of the following:
An account of the design of the proposed Closure Plan that is based on the site hydrogeologic conceptual model developed and includes (i) predictions on post -closure groundwater elevations and groundwater flow directions and
velocities, including the effects on and from the potential receptors and
1
(ii) predictions at the compliance boundary for substances with concentrations determined to be in excess of the groundwater quality standards for the substance established by Subchapter L of Chapter 2 of Title 15A of the North Carolina
5.1
Administrative Code.
Predictions that include the effects on the groundwater chemistry and should describe migration, concentration, mobilization, and fate for substances with concentrations determined to be in excess of the groundwater quality standards
2
for the substance established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code pre- and post -closure, including the effects on and from potential receptors.
5.2
A description of the groundwater trend analysis methods used to demonstrate compliance with groundwater quality standards for the substance established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative
3
Code and requirements for corrective action of groundwater contamination established by Subchapter L of Chapter 2 of Title 15A of the North Carolina Administrative Code.
5.3
A description of any plans for beneficial use of the coal combustion residuals in compliance with the requirements of Section .1700 of Subchapter B of Chapter 13 of Title 15A of the North Carolina Administrative Code (Requirements
e
for Beneficial Use of Coal Combustion By -Products) and Section .1205 of Subchapter T of Chapter 2 of Title 15A of the North Carolina Administrative Code (Coal Combustion Products Management).
6.1
f
All engineering drawings, schematics, and specifications for the proposed Closure Plan. If required by Chapter 89C of the General Statutes, engineering design documents should be prepared, signed, and sealed by a professional
7 1 7 2
engineer.
A description of the construction quality assurance and quality control program to be implemented in conjunction with the Closure Plan, including the responsibilities and authorities for monitoring and testing activities, sampling
g
strategies, and reporting requirements.
7 3
h.
A description of the provisions for disposal of wastewater and management of stormwater and the plan for obtaining all required permits.
8
A description of the provisions for the final disposition of the coal combustion residuals. If the coal combustion residuals are to be removed, the owner must identify (i) the location and permit number for the coal combustion
residuals landfills, industrial landfills, or municipal solid waste landfills in which the coal combustion residuals will be disposed and (ii) in the case where the coal combustion residuals are planned for beneficial use, the location and
manner in which the residuals will be temporarily stored. If the coal combustion residuals are to be left in the impoundment, the owner
L
must (i) in the case of closure pursuant to sub -subdivision (a)(1)a. of this section, provide a description of how the ash will be stabilized prior to completion of closure in accordance with closure and post -closure requirements
9
established by Section .1627 of Subchapter B of Chapter 13 of Title 15A of the North Carolina Administrative Code and (ii) in the case of closure pursuant to sub -subdivision (a)(1)b. of this section, provide a description of how the ash
will be stabilized pre- and post -closure. If the coal combustion residuals are to be left in the impoundment, the owner must provide an estimate of the volume of coal combustion residuals remaining.
j.
A list of all permits that will need to be acquired or modified to complete closure activities.
10
A description of the plan for post -closure monitoring and care for an impoundment for a minimum of 30 years. The length of the post -closure care period may be (i) proposed to be decreased or the frequency and parameter list
modified if the owner demonstrates that the reduced period or modifications are sufficient to protect public health, safety, and welfare; the environment; and natural resources and (ii) increased by the Department at the end of the
k
post -closure monitoring and care period if there are statistically significant increasing groundwater quality trends or if contaminant concentrations have not decreased to a level protective of public health, safety, and welfare; the
environment; and natural resources. If the owner determines that the post -closure care monitoring and care period is no longer needed and the Department agrees, the owner shall provide a certification, signed and sealed by a
11
professional engineer, verifying that post -closure monitoring and care has been completed in accordance with the post -closure plan. If required by Chapter 89C of the General Statutes, the proposed plan for post -closure monitoring
and care should be signed and sealed by a professional engineer. The plan shall include, at a minimum, all of the following:
1
A demonstration of the long-term control of all leachate, affected groundwater, and stormwater.
11.1
A description of a groundwater monitoring program that includes (i) post -closure groundwater monitoring, including parameters to be sampled and sampling schedules; (ii) any additional monitoring well installations, including a map with
2
the proposed locations and well construction details; and (iii) the actions proposed to mitigate statistically significant increasing groundwater quality trends.
11.2
I.
An estimate of the milestone dates for all activities related to closure and post -closure.
12.1
m.
Projected costs of assessment, corrective action, closure, and post -closure care for each coal combustion residuals surface impoundment.
12.2
2OF3

AECOM Table 2-1: NC CAMA Closure Plan Requirements November 6, 2019
Summary and Cross Reference Table
Duke Energy, Marshall Steam Station
Corresponding Closure
No.
Description
Plan Section
A description of the anticipated future use of the site and the necessity for the implementation of institutional controls following closure, including property use restrictions, and requirements for recordation of notices documenting
n
the presence of contamination, if applicable, or historical site use.
6.2
§ 130A-309.214(b)(3)
No later than 60 days after receipt of a proposed Closure Plan, the Department shall conduct a public meeting in the county or counties proposed Closure Plan and alternatives to the public.
Note 1
Reports Prepared by Other Consultants Include:
1 Synterra Groundwater Assessment Work Plan
2 HDR Groundwater Assessment Work Plan
3OF3

Aa=wCOM
Closure Plan
Table 4-1A - Summary of Soil Laboratory Test Results for CCR (by AECOM and Other Consultants)"
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Shear
Strength
Undrained
Shear
Strength
Unconfined
Compressive
Strength
SB-102
Shelby Tube
ST-4
26.0 - 28.0
Bottom Ash as SILTY SAND (SM)
49.3
NP
NP
NP
22.0
6.2
71.8
2.210
95
64
Shelby Tube
ST-5
33.0 - 35.0
Bottom Ash as SANDY SILT (ML)
45.2
NP
49
NP
10.3
5.3
84.4
2.179
89
54
AECOM
Ash
SB-213
Shelby Tube
ST-3
28.0 - 30.0
Bottom Ash as SILTY SAND (SM)
61.2
28.0
3.5
68.5
92
57
Basin
Shelby Tube
ST-5
4.0 - 6.0
Bottom Ash as Poorly -Graded SAND (SP-SM)
37.6
7.1
11.8
81.1
84
61
SB-214
Shelby Tube
ST-6
8.0 - 10.0
Bottom Ash as Poorly -Graded SAND (SP-SM)
47.3
1
7.0
8.7
1 84.3
89
61
Shelby Tube
ST-9
38.0 - 40.0
Fly Ash as SANDY SILT (ML)
36.8
64.7
0.6
34.7
1021
75
Split Spoon
SS-3
13.5 - 15.0
Black SANDY SILT (ML), ash
47.8
NP
NP
NP
78.6
0.0
21.4
69.8
8.8
P-5/13-2
Split Spoon
SS-4
33.5 - 35.0
Gray Black SILTY SAND (SM), ash
35.6
NP
NP
NP
16.3
16.1
67.6
15.1
1.2
B-4A
Shelby Tube
UD-1
13.5 - 15.5
Brown Tan Gray SILTY SAND (SM), ash
22.5
NP
NP
NP
38.8
2.8
58.4
28.4
10.4
2.790
91
4.18E-05
Bag
BAG-1
0.0 - 10.0
Gray SILT (ML), ash
NP
NP
NP
69.5
0.3
30.2
58.6
10.9
75.7
17.4
2.230
Split Spoon
SS-6
1.0 - 2.5
Gray SILT (ML), ash
38.2
NP
NP
NP
70.5
0.9
28.6
65.0
5.5
P-3
Shelby Tube
LID-2
10.0 - 12.0
Gray SILT (ML), ash
28.0
NP
NP
NP
95.5
0.0
4.5
85.2
10.3
2.270
73
1.97E-04
Split Spoon
SS-6
18.5 - 20.0
Gray Brown SANDY SILT (ML), ash
37.5
NP
NP
NP
70.5
Split Spoon
SS-7
6.0 - 7.5
Gray SILTY SAND (SM), ash
49.2
P-6
Shelby Tube
UD-3
10.0 - 12.0
Gray SILT (ML), ash
41.9
NP
NP
NP
30.2
17.8
52
27.0
3.2
2.320
Split Spoon
SS-8
18.5 - 20.0
Gray SILTY SAND (SM), ash
42.3
NP
NP
NP
16.8
4.0
79.2
13.7
3.1
M-5
Split Spoon
85
8.6 - 10.1
Dark Gray SILT, ash
77.4
0.1
22.5
73.1
4.3
1.03E-03
Split Spoon
1.0 - 2.5
Ash
43.8
Split Spoon
3.5 - 5.0
Ash
39.4
Split Spoon
6.0 - 7.0
Ash
35.3
Split Spoon
8.0 - 9.0
Ash
28.0
STB-2
Split Spoon
13.0 - 14.0
Ash
44.6
Split Spoon
18.0 - 19.0
Ash
45.2
S&ME
Ash
Basin
Split Spoon
23.0 - 24.0
Ash
33.5
77.8
69.8
8.0
Split Spoon
33.0 - 34.0
Ash
30.0
Split Spoon
38.0 - 39.0
Ash
29.4
Split Spoon
1.0
Ash
25.4
Split Spoon
3.0 - 4.0
Ash
43.9
Split Spoon
5.0 - 6.0
Ash
32.5
Split Spoon
13.0 - 14.0
Ash
48.6
Split Spoon
18.0 - 19.0
Ash
54.3
STB-3
Split Spoon
23.0 - 24.0
Ash
55.1
Split Spoon
28.0 - 29.0
Ash
54.1
Split Spoon
33.0 - 34.0
Ash
53.6
Split Spoon
38.0 - 39.0
Ash
116.0
Split Spoon
43.0 - 44.0
Ash
35.0
97.1
81.1
16.0
Split Spoon
48.0 - 49.0
Ash
34.1
FPS
6.0 - 8.0
Ash
88.2
75.2
13.0
VS-1
FPS
16.0 - 18.0
Ash
88.6
78.1
10.5
VS-2
FPS
24.0 - 26.0
Ash
79.7
72.2
7.5
VS-3
FPS
30.0 - 32.0
Ash
95.4
75.9
19.5
AB-3D
Split Spoon
Jar
29.0 - 30.5
Fly Ash
45.1
20.8
11.2
68.4
19.4
1.4
AB-4D
Split Spoon
Jar
19.0 - 20.5
Fly Ash
86.7
30.5
0.6
68.9
29.1
1.4
AB-6D
Split Spoon
Jar
9.0 - 10.5
Fly Ash
56.1
50.9
0.3
48.8
49.6
1.3
HBR
Ash Basin
AB-7D
Shelby Tube
UD
0.0-2.5
Fly Ash (ML)
NP
NP
NP
85.7
0.0
14.3
70.8
14.9
2.164
1.19E-04
AB-12D
Split Spoon
Jar
39.0 - 40.5
Fly Ash
32.1
77.3
0.0
22.7
68.0
9.3
AB-15D
Sonic
Jar
44.0 - 45.0
Fly Ash
28.7
86.6
0.0
13.4
72.4
14.2
AB-18D
Split Spoon
Jar
9.0 - 10.5
Fly Ash
59.8
72.0
1.2
26.8
67.4
4.6

Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of impountment.

A=COM
Closure Plan
Table 4-1 B - Summary of Soil Laboratory Test Results for Alluvial Soils (by AECOM and Other Consultants)"
Atterberg Limits
Grain
Size Analysis
Standard Proctor
Test
Unit Weight
(pcf)
Strength Testing
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Shelby Tube
ST-2
6.0 - 8.0
SILTY SAND (SM), alluvium
24.6
39
31
8
34.1
0.1
65.8
2.703
116
93
STB-2
Split Spoon
43.0 - 44.0
alluvium
23.2
S&ME
Ash Basin
STB-3
Split Spoon
53.0 - 54.0
alluvium
28.9
AB-9BR
Shelby Tube
UD
11.0 - 12.5
Olive -Brown SILTY SAND (SM), Alluvium
NP
NP
NP
13.9
0.0
86.1
9.0
4.9
2.802
5.92E-05
HDR
Ash Basin
AB-11 D
Split Spoon
Jar
12.3 - 13.3
Red -Brown SILTY SAND, Alluvium
17.6
13.0
0.0
87.0
9.4
3.6
Shelby Tube
LID
12.5 - 13.5
Tan -Brown SILTY SAND (SM), Alluvium
NP
NP
NP
17.9
0.2
81.9
13.9
4.0
2.622
5.64E-05
Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of impountment.

A=Com
Closure Plan
Table 4-1C - Summary of Soil Laboratory Test Results for Residual Soils (by AECOM and Other Consultants)"
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°J
>.
L
CU
Triaxial
Shear
Strength
Undrained
Shear
Strength
g
Unconfined
Compressive
Strength
g
SB-101
Split Spoon
S-9
44.0 - 46.0
Brown SANDY SILT (ML), residuum
21.9
47
30
17
57.5
0.0
42.5
35.5
22.0
Split Spoon
S-10
49.0 - 51.0
Reddish Brown CLAYEY ELASTIC SILT (MH), residuum
24.4
52
24
28
29.6
8.4
42.0
23.6
26.0
SB-102
Split Spoon
S-11
60.0 - 62.0
Light Brown SILTY SAND (SM), residuum
31.5
40
36
4
38.0
0.5
61.5
34.0
4.0
Shelby Tube
ST-3
21.0-23.0
SANDY SILT (ML), residuum
33.6
49
38
11
54.6
2.7
42.7
2.320
118.2
88.5
Ash Basin
SB-103
Split Spoon
S-5
24.0 - 26.0
Orangish SANDY ELASTIC SILT (MH), residuum
32.2
53
36
17
59.9
0.0
40.1
32.9
27.0
Split Spoon
S-8
38.0 - 40.0
Brown SILTY SAND (SM), residuum
12.9
NP
NP
NP
32.5
0.0
67.5
29.5
3.0
Split Spoon
S-4
19.0 - 21.0
Brown SILTY SAND (SM), residuum
27.2
44
44
0
29.8
0.4
69.8
25.8
4.0
SB-104
Split Spoon
S-6
29.0 - 31.0
Brown SILTY SAND (SM), residuum
17.7
42
48
NP
29.9
0.5
69.6
26.9
3.0
Split Spoon
S-7
34.0 - 36.0
Brown SILTY SAND (SM), residuum
11.0
36.1
0.6
63.3
33.1
3.0
Shelby Tube
2
35.0 - 37.0
Brown and White SILTY SAND (SM), residuum
21.0
43
30
13
125.0
104.5
Split Spoon
12
45.0 - 47.0
Red Brown SILTY SAND (SM), residuum
40.8
NP
NP
NP
31.7
0.0
68.3
Split Spoon
13
50.0 - 52.0
Red Brown SILTY SAND (SM), residuum
37.4
B-100
Shelby Tube
3
55.0 - 57.0
Red Brown SILTY SAND (SM), residuum
28.1
NP
NP
NP
32.1
0.0
67.9
29.9
2.2
116.0
Split Spoon
15
60.0 - 62.0
Mottled Brown SILTY SAND (SM), residuum
22.7
NP
NP
NP
21.0
0.3
78.8
Split Spoon
16
65.0 - 67.0
Mottled Brown SANDY SILTY (ML), residuum
26.9
Shelby Tube
2
35.0 - 37.0
Red Brown Sandy SILTY (ML), residuum
37.4
NP
NP
NP
59.8
0.0
40.2
56.4
3.4
107.0
B-101
Split Spoon
9
50.0 - 52.0
Mottled Brown SILTY SAND (SM), residuum
17.5
26.6
0.0
73.4
Shelby Tube
3
43.0 - 45.0
Brown SANDY SILT (ML), residuum
28.3
NP
NP
NP
53.0
0.0
47.0
45.6
7.4
115.0
3.50E-07
B-102
Split Spoon
10
49.0 - 51.0
Brown SANDY SILT (ML), residuum
6.9
Split Spoon
12
59.0 - 61.0
Brown SILTY SAND (SM), residuum
37.1
33.2
0.0
66.8
B-105
Split Spoon
13
70.0 - 72.0
Gray Brown SILTY SAND (SM), residuum
16.5
23.0
0.3
76.7
Shelby Tube
2
23.0 - 25.0
Brown to Dark Brown SILTY SAND (SM), residuum
23.3
NP
NP
NP
32.8
0.0
67.2
28.2
4.6
110.0
1.40E-04
AECOM
Split Spoon
8
29.0 - 31.0
Brown to Dark Brown SILTY SAND (SM), residuum
40.9
43
38
5
35.5
0.0
64.5
B-106
Shelby Tube
3
43.0 - 45.0
Brown to Dark Brown SILTY SAND (SM), residuum
43.5
NP
NV
NP
26.2
0.0
73.8
24.0
2.2
109.0
3.60E-04
Split Spoon
11
49.0 - 51.0
Orange to Light Brown SILTY SAND (SM), residuum
35.6
33
NP
1
43.6
0.0
56.4
Split Spoon
13
59.0 - 61.0
Brown SAND with SILT (SP-SM), residuum
30.5
10.4
0.0
89.6
Ash Basin
Split Spoon
15
69.0 - 69.3
Brown SILTY SAND (SM), residuum
16.2
33
28
5
23.0
0.4
76.6
Dam
Split Spoon
2
10.0 - 12.0
Orange Brown CLAYEY SANDY SILT (ML), residuum
39.7
37
33
4
53.7
0.0
46.3
Split Spoon
3
15.0 - 17.0
Mottled Brown SILTY SAND (SM), residuum
40.9
NP
NP
NP
22.7
0.1
77.3
B-107
Shelby Tube
2
20.0 - 22.0
Mottled Brown SILTY SAND (SM), residuum
38.3
46
30
16
64.6
0.0
35.4
27.7
36.9
111.0
19.0
NP
NP
NP
27.4
0.0
72.6
Split Spoon
6
30.0 - 32.0
Brown to Orange Brown SANDY SILT (ML), residuum
25.3
NP
NP
NP
61.9
0.0
38.1
Split Spoon
8
40.0 - 41.0
Brown to Orange Brown SANDY SILT (ML), residuum
17.6
Split Spoon
2
2.0 - 4.0
Mottled Brown LEAN CLAY (CL), residuum
14.3
33
22
11
21.6
16.1
62.3
Split Spoon
3
4.0 - 6.0
Orange Brown SILTY SANDY GRAVEL (GW), residuum
22.9
Split Spoon
5
8.0 - 10.0
Orange Brown SANDY SILT (ML), residuum
17.0
NP
NP
NP
28.9
4.8
66.3
Split Spoon
6
15.0 - 17.0
Orange Brown SANDY SILT (ML), residuum
10.2
B-108
Split Spoon
7
20.0 - 22.0
Orange Brown SANDY SILT (ML), residuum
25.7
28
25
3
29.8
0.6
69.6
Split Spoon
8
25.0 - 27.0
Brown, White, and Light Gray CLAYEY SILT (ML), residuum
26.6
Split Spoon
9
30.0 - 32.0
Pale Green SILTY SAND (SM), residuum
36.7
NP
NP
NP
39.8
0.0
60.2
Split Spoon
10
35.0 - 37.0
Pale Green SILTY SAND (SM), residuum
32.2
Split Spoon
12
45.0 - 47.0
Dark Brown SILTY SAND (SM), residuum
16.5
NP
NP
NP
25.5
0.0
74.5
Split Spoon
2
2.0 - 4.0
Orange Red SANDY SILT (ML), residuum
21.6
46
29
17
61.3
0.0
38.7
115.0
B-109
Split Spoon
5
8.0 - 10.0
Orange Red SANDY SILT (ML), residuum
29.2
45
40
5
43.6
0.0
56.5
Split Spoon
13
49.0 - 51.0
Light Brown to White SILTY SAND (SM), residuum
19.1
NP
NP
NP
23.4
0.0
76.6
128.0
107
Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of impountment.

A=Com
Closure Plan
Table 4-1C - Summary of Soil Laboratory Test Results for Residual Soils (by AECOM and Other Consultants)"
o
t�
Q
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=
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Atterberg Limits
Grain Size Analysis
Standard Proctor Test
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Unit Weight
(pcf)
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Testing
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Triaxial
Shear
Strength
Undrained
Shear
Strength
g
Unconfined
Compressive
Strength
g
Split Spoon
2
2.0 - 4.0
Brown CLAYEY SILT (ML), residuum
28.9
45
41
4
61.2
0.0
38.8
Split Spoon
3
4.0 - 6.0
Brown CLAYEY SILT (ML), residuum
26.9
50.0
3.5
46.5
Split Spoon
5
8.0 - 10.0
Brown CLAYEY SILT (ML), residuum
38.6
44
42
2
64.5
0.0
1 35.5
102.0
74
B-110
Split Spoon
6
14.0 - 16.0
Brown CLAYEY SILT (ML), residuum
30.3
Split Spoon
8
24.0 - 26.0
Red Brown SILT (ML), residuum
49.6
NP
NP
NP
53.0
0.0
47.0
Split Spoon
10
34.0 - 36.0
Red Brown SILT (ML), residuum
42.1
NP
NP
NP
Split Spoon
12
44.0 - 46.0
Gray SILTY SAND (SM), residuum
22.3
23.5
0.0
76.5
Split Spoon
S-6
29.0 - 31.0
Brown SILTY SAND (SM), residuum
25.3
NP
NP
NP
40.0
Split Spoon
S-7
34.0 - 36.0
Brown SILTY SAND (SM), residuum
NP
NP
NP
36.0
B-111
Split Spoon
S-8
36.0 - 38.0
Brown SILTY SAND (SM), residuum
34.9
NP
NP
NP
29.6
Split Spoon
S-9
38.0 - 40.0
Brown SILTY SAND (SM), residuum
NP
NP
NP
23.9
Split Spoon
S-10
42.0 - 44.0
Brown SILTY SAND (SM), residuum
NP
NP
NP
34.3
Split Spoon
S-3
14.0 - 16.0
Brown SILTY SAND (SM), residuum
33.5
NP
NP
NP
24.8
2.680
AECOM
Ash Basin
Shelby Tube
ST-9
16.0 - 18.0
Brown SILTY SAND (SM), residuum
30.0
43
41
2
22.0
2.677
112.1
NP
NP
NP
24.0
2.682
45
39
6
2.677
B-112
Split Spoon
S-4
18.0 - 20.0
Brown SILTY SAND (SM), residuum
NP
NP
NP
24.0
Split Spoon
S-5
20.0-22.0
Brown SILTY SAND (SM), residuum
NP
NP
NP
24.2
Split Spoon
S-6
22.0-24.0
Brown SILTY SAND (SM), residuum
NP
NP
NP
22.0
Shelby Tube
ST-10
24.0 - 26.0
Brown SILTY SAND (SM), residuum
27.8
NP
NP
NP
20.0
116.1
28.4
NP
NP
NP
21.0
120.8
Shelby Tube
S-8
28.0 - 30.0
Brown SILTY SAND (SM), residuum
23.0
Split Spoon
S-7
34.0 - 36.0
Brown SILT (ML), residuum
25.8
36
30
6
47.5
B-113
Shelby Tube
ST-2
36.0 - 38.0
Gray SILTY SAND (SM), residuum
Split Spoon
S-8
38.0 - 40.0
Brow and White SILTY SAND (SM), residuum
NP
NP
NP
32.0
Split Spoon
S-8
39.0 - 41.0
Brown to Grayish SILTY SAND (SM), residuum
NP
NP
NP
20.5
B-114
Shelby Tube
ST-8
41.0 - 43.0
Brown to Grayish SILTY SAND (SM), residuum
Split Spoon
S-12
59.0 - 61.0
Brown to Grayish SILTY SAND (SM), residuum
22.0
C-4
Shelby Tube
749
50.0 - 52.0
Brown Gray SILTY SAND (SM), residuum
27.5
NP
NP
NP
19.9
0.0
80.1
16.9
3.0
2.700
112.0
Ash
Basin
C-7
Shelby Tube
759
39.1 - 41.1
Yellow Brown/Gray SILTY SAND (SM), residuum
21.6
NP
NP
NP
41.6
0.0
58.4
36.8
4.8
2.700
118.8
99
2.96E-06
Duke
Dam
Shelby Tube
719
79.1 - 81.1
Yellow Gray SILTY SAND (SM), residuum
36.0
NP
NP
NP
29.6
0.0
70.4
27.6
2.0
2.730
111.0
3.70E-04
C-10
Shelby Tube
755
40.0 - 42.0
Reddish Gray SILTY SAND (SM), residuum
31.0
45
35
10
46.0
0.0
54.0
38.1
7.9
2.700
110.2
80
5.34E-06
B-1
Split Spoon
SS-1
8.5 - 10.0
Brown Tan Gray SILTY SAND (SM), residuum
38.1
NP
NP
NP
37.9
0.0
62.1
28.5
9.4
S&ME
Ash Basin
STB-3
Split Spoon
58.0 - 59.0
residuum
14.2
AB-3D
Shelby Tube
UD
76.0 - 78.2
Orange -Gray SILTY SAND (SM), saprolite
24
31
7
39.9
0.0
60.1
19.1
20.8
2.615
6.52E-07
AB-4D
Shelby Tube
UD
55.5 - 56.5
Tan -Brown SILTY SAND (SM), saprolite
NP
NP
NP
17.0
1.2
81.8
13.8
3.2
2.653
6.42E-05
AB-6D
Split Spoon
Jar
51.0 - 53.0
Tan -Brown and Black SILTY SAND, saprolite
19.6
18.8
2.1
79.1
16.4
2.4
AB-8D
Shelby Tube
UD
30.5 - 32.1
Orange -Brown CLAYEY SAND (SC), saprolite
25
40
15
46.4
0.0
53.6
20.5
25.9
2.575
6.23E-07
AB-10D
Sonic
Jar
52.0
Brown CLAYEY SAND, saprolite
20.9
40.1
0.0
59.9
18.9
21.2
HDR
Basin
AB-11D
Shelby Tube
UD
9.0 - 11.5
Orange -Brown CLAYEY SAND (SC), saprolite
24
50
26
34.5
0.8
64.7
9.1
25.4
2.615
9.73E-06
AB-12D
Split Spoon
Jar
49.0 - 50.5
Gray -Brown SILTY SAND, saprolite
31.9
13.6
0.7
85.7
7.0
6.6
AB-14D
Shelby Tube
UD
45.0 - 45.8
Olive -Gray SILTY SAND (SM), saprolite
NP
NP
NP
22.1
0.0
77.9
20.0
2.1
2.706
1.33E-04
AB-15D
Sonic
Jar
48.0 - 49.0
Orange -Brown Elastic SILT, saprolite
24.7
55.3
0.0
44.7
19.4
35.9
AB-18D
Shelby Tube
UD
39.0 - 39.5
Olive -Brown SILTY SAND (SM), saprolite
NP
NP
NP
18.8
0.0
81.2
16.1
2.7
2.648
AB-21 D
Shelby Tube
UD
37.0 - 39.0
Olive -Tan SILTY SAND (SM), saprolite
NP
NP
NP
19.7
0.0
80.3
13.0
6.7
2.731
1.68E-06

A=Com
Closure Plan
Table 4-1C - Summary of Soil Laboratory Test Results for Residual Soils (by AECOM and Other Consultants)"
+,
Atterberg Limits
Grain Size Analysis
Standard Proctor Test
Unit Weight
(pcf)
Strength Testing
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Unconfined
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Compressive
t�
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Strength
g
Strength
g
m
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Strength
N
v
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Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of impountment.

A=COM
Closure Plan
Table 4-1 D - Summary of Soil Laboratory Test Results for Partially Weathered Rock (by AECOM and Other Consultants)"
Atterberg Limits
Grain Size Analysis
Standard Proctor Test
Unit Weight
(pcf)
Strength Testing
i
L
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Unconfined
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Compressive
v
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o
p
a
v a ..
v
Strength
Strength
Strength
Q
Cn
Split Spoon
18
75.0 - 76.0
Orange Brown SAND with SILT (SP-SM)
14.7
NP
NP
NP
7.8
2.3
89.9
B-100
Split Spoon
19
80.0 - 81.0
Orange Brown SILTY SAND (SM)
19.4
NP
NP
NP
31.0
0.0
69.0
Ash
B-101
Split Spoon
11
60.0 - 61.5
Brown, Gray, and White SILTY SAND (SM)
20.5
31.2
0.0
68.8
AECOM
Basin
Split Spoon
14
69.0 - 69.3
SILTY SAND (SM)
14.7
23.9
0.5
75.6Dam
B-102
Split Spoon
16
79.0 - 79.3
SILTY SAND (SM)
16.1
27.9
1.5
70.6
129
111
B-103
Split Spoon
21
99.0 - 100.3
Brown to Light Brown SILTY SAND (SM)
16.5
32
24
8
30.5
0.0
69.5
Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of impountment.

AECOM
Closure Plan
Table 4-1 E - Summary of Soil Laboratory Test Results for Embankment Fill Material (by AECOM and Other Consultants)"
'
o
t�
Q
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m
°'
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a
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USCS Classification
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Grain Size Analysis
Standard Proctor
Test
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Testing
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Shear
Strength
g
Undrained
Shear
Strength
Unconfined
Compressive
Strength
Split Spoon
3
4.0 - 6.0
Light Brown SILTY SAND (SM), fill
17.3
NP
NP
NP
45.5
0.1
54.4
Shelby Tube
1
10.0 - 12.0
Light Brown SANDY SILT (ML), fill
22.5
NP
NP
NP
52.0
0.0
48.0
45.4
6.6
121
100
Split Spoon
6
15.0 - 17.0
Light Brown SILTY SAND (SM), fill
18.5
NP
NP
NP
46.7
0.0
53.3
B-100
Split Spoon
7
20.0 -22.0
Light Brown SILTY SAND (SM), fill
18.2
Split Spoon
8
25.0 - 27.0
Light Brown SILTY SAND (SM), fill
19.1
NP
NP
NP
45.4
0.3
54.3
Split Spoon
9
30.0 - 32.0
Light Brown SILTY SAND (SM), fill
21.1
48.5
0.2
51.3
B-101
Split Spoon
2
15.0 - 17.0
Orange Brown SANDY SILT (ML), fill
18.2
34
30
4
60.1
0.7
39.2
Shelby Tube
1
20.0 - 22.0
Orange Brown SILTY SAND (SM), fill
27.7
NP
NP
NP
29.8
4.8
65.4
114
4.80E-04
Split Spoon
2
2.0 - 4.0
Brown SANDY SILT (ML), fill
15.1
Split Spoon
4
6.0 - 8.0
Light Brown to Light Gray SILTY SAND (SM), fill
24.9
NP
NP
NP
Shelby Tube
1
13.0 - 15.0
Light Brown to Light Gray CLAYEY SAND (SC), fill
12.8
28
20
8
43.1
16.1
40.8
30.5
12.6
B-102
Shelby Tube
2
23.0 -25.0
Brown to Red Brown SILTY SAND (SM), fill
34.7
NP
NP
NP
36.5
0.2
63.3
2.680
111
82
1.60E-05
Split Spoon
7
29.0 - 31.0
Brown to Orange Brown SANDY SILT (ML), fill
33.5
52.2
0.0
47.8
Split Spoon
8
34.0 - 36.0
Brown to Orange Brown SILTY SAND (SM), fill
34.7
NP
NP
NP
38.8
0.2
61.0
Split Spoon
9
39.0 - 41.0
Brown to Orange Brown SILTY SAND (SM), fill
34.9
Split Spoon
3
5.0 - 6.0
Light Brown SILTY SAND (SM), fill
20.6
33
25
8
119
98
Split Spoon
4
6.0 - 8.0
Light Brown SILTY SAND (SM), fill
21.0
33
25
8
Shelby Tube
1
10.0 - 12.0
Light Brown SILTY SAND (SM), fill
19.8
NP
NP
NP
46.3
0.2
53.4
39.9
6.4
130
104
Split Spoon
6
14.0 - 16.0
Light Orange Brown SANDY SILT (ML)
22.4
41
28
13
55.7
0.0
44.3
118
Shelby Tube
2
23.0 - 25.0
Light Brown SILTY SAND (SM), fill
17.3
35
29
6
37.5
24.1
38.4
28.4
9.1
126
Split Spoon
8
29.0 - 31.0
Light Brown SANDY SILT (ML), fill
27.2
43
35
8
58.2
0.1
41.7
B-103
Split Spoon
9
34.0 - 36.0
Light Orange Brown SILTY SAND (SM), fill
25.2
120
95
Shelby Tube
3
43.0 - 45.0
Light Orange Brown SILTY SAND (SM), fill
22.1
NP
NP
NP
44.5
0.5
55.0
35.2
9.3
120
3.50E-07
Split Spoon
11
49.0 - 51.0
Light Orange Brown SILTY SAND (SM), fill
22.0
34
29
5
42.2
0.3
57.5
Ash Basin
Split Spoon
13
59.0 - 61.0
Light Orange Brown SILTY SAND (SM), fill
22.8
34
32
2
42.8
0.0
57.3
117
95
AECOM
Dam
Split Spoon
15
69.0 - 71.0
Brown to Orange SANDY SILT (ML), fill
28.6
45
29
16
Split Spoon
18
84.0 - 86.0
Red Brown SANDY SILT (MH), fill
35.1
67
40
27
70.8
0.8
28.5
Split Spoon
19
89.0 - 91.0
Red Brown SANDY SILT (MH), fill
38.2
98
71
Split Spoon
1
10.0 - 12.0
Brown SILTY SAND (SM), fill
22.7
40.9
0.5
58.7
Split Spoon
3
20.0 - 22.0
Brown SILTY SAND (SM), fill
21.4
34.8
2.3
62.9
Split Spoon
4
30.0 - 32.0
Red Brown SILT (ML), fill
20.9
48
34
14
60.2
1.7
38.1
B-104
Split Spoon
6
40.0 - 42.0
Red Brown to Brown SILTY SAND (SM), fill
22.7
42.4
0.5
57.1
Split Spoon
8
50.0 - 52.0
Red Brown to Brown SILTY SAND (SM), fill
28.5
43
33
10
49.3
0.1
50.7
Split Spoon
9
55.0 - 57.0
Red Brown to Brown SILTY SAND (SM), fill
31.6
101
76
Split Spoon
11
65.0 - 67.0
Red Brown CLAYEY ELASTIC SILT (MH), fill
29.6
66
41
25
58.5
3.5
38.0
Split Spoon
3
15.0 - 17.0
Light Brown SILTY SAND (SM), fill
19.5
NP
NP
NP
34.4
1.2
64.3
Split Spoon
5
25.0 - 27.0
Light Brown CLAYEY SAND (SC), fill
20.9
24
15
9
33.1
1.6
65.3
B-105
Split Spoon
6
30.0 - 32.0
Light Brown SILTY SAND (SM), fill
20.3
35.3
1.8
62.9
Split Spoon
8
40.0 - 42.0
Light Brown to Light Gray SILTY SAND (SM), fill
20.7
NP
NP
NP
22.8
3.0
74.2
Split Spoon
10
50.0 - 52.0
Light Brown to Light Gray SILTY SAND (SM), fill
21.8
Split Spoon
11
60.0 - 62.0
Light Brown to Light Gray SILTY SAND (SM), fill
35.4
NP
NP
NP
34.3
0.1
65.6
Split Spoon
3
4.0 - 6.0
Brown SANDY SILT (ML), fill
23.7
39
31
8
51.2
0.5
48.4
114
92
B-106
Shelby Tube
1
10.0 - 12.0
Brown SANDY SILT (ML), fill
22.2
39
35
4
53.0
0.0
47.0
38.8
14.2
119
Split Spoon
6
14.0 - 16.0
Brown SANDY SILT (ML), fill
23.9
45
33
12
55.7
0.5
43.9
151
122
B-107
Shelby Tube
1
5.0 - 7.0
Red Brown CLAYEY SILT (MH), fill
28.4
54
40
14
66.2
0.0
33.8
28.4
37.8
116
Split Spoon
1
7.0 - 9.0
Red Brown CLAYEY SILT (MH), fill
34.3
49
38
11
58.3
0.0
41.8
B-110
Bulk
Bulk
0.0 - 10.0
Red SILT (ML), fill
19.7
41
27
14
50.0
3.5
46.5
107.1
15.1
Shelby Tube
ST-6
6.0 - 8.0
SANDY SILT (ML), fill
19.3
NP
NP
NP
35.0
0.0
64.6
B-114
Shelby Tube
ST-7
16.0 - 18.0
SILTY SAND (SM), fill
19.2
NP
NP
NP
37.0
0.0
62.8
22.1
NP
NP
NP
35.0
119
98
*
Ash Basin
SB-102
Split Spoon
S-3
14.0 - 16.0
Brown SILTY SAND (ML), fill
17.5
44
30
14
48.3
1.0
50.7
35.3
13.0

AECOM
Closure Plan
Table 4-1 E - Summary of Soil Laboratory Test Results for Embankment Fill Material (by AECOM and Other Consultants)"
Atterberg Limits
Grain Size Analysis
Standard Proctor
Test
Unit Weight
(pcf)
Strength
Testing
E
r
'
Q
Z
p
o
U
o
>
=
M
o
�� y
CU Triaxial
Undrained
Unconfined
'
y
�'
°'
a
USCS Classification
i :..
J
J
N
<3
_
`�
a,
E i
V
41
Gl
i
C U)
o
Q
£
m
_j
a
a
>
C
v
L Q.
42
o
m
y
Shear
Shear
Compressive
t�
Cl)
N
v
o
o
c �-
O 0
a
c
o
Strength
g
Strength
Strength
m
N
U a
U
Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of immuntment.
C-4
Shelby Tube
789
9.5 - 11.5
Olive Yellow SILTY SAND (SM), fill
20.6
NP
NP
NP
46.7
0.0
53.3
41.8
4.9
2.730
123
C-6
Shelby Tube
771
3.0 - 6.6
Light Brown Gray SILTY SAND (SM), fill
16.7
NP
NP
NP
30.7
2.5
66.8
65.0
1.8
2.750
134
Shelby Tube
770
5.0 - 6.6
SILT (ML)
17.8
30
23
7
128
108
4.69E-07
Duke
Ash Basin
C-7
Shelby Tube
777
19.1 - 21.1
Yellow Brown CLAYEY SANDY SILT (SM-ML), fill
19.6
38
28
10
47.6
1.2
51.2
40.7
6.9
2.700
127
C-8
Shelby Tube
776
9.4 - 11.4
Yellowish Gray SILTY SAND (SM), fill
18.2
NP
NP
NP
25.3
0.0
74.7
22.5
2.8
2.730
122
103
5.28E-07
C-10
Shelby Tube
790
5.0 - 7.0
Yellowish Brown SILTY SAND (SM), fill
23.3
NP
NP
NP
48.7
0.0
51.3
43.7
5.0
2.720
121
1.38E-06
Shelby Tube
775
20.0 - 22.0
Light Yellow Brown SILTY SAND (SM), fill
20.9
30
26
4
42.0
0.0
58.0
33.4
8.6
2.670
126
1.05E-06
S&ME
Ash Basin
P-5/13-2
Split Spoon
SS-2
8.5 - 10.0
Red Brown SANDY SILT (ML), fill
27.9
B-4
Split Spoon
SS-5
6.0 - 7.5
Red Brown SAND CLAYEY SILT (MH), fill
19.6
Sonic
Jar
4.0 - 5.0
Brown CLAYEY SILTY SAND, fill
15.1
40.1
0.1
59.8
22.0
18.1
Sonic
Jar
9.0 - 10.0
Red -Brown CLAEY SILTY SAND, fill
23.9
44.7
0.0
55.3
24.2
20.5
AB-1 BR
Sonic
Jar
14.0 - 15.0
Red -Brown SANDY SILT, fill
28.1
52.2
0.0
47.8
30.9
21.3
Shelby Tube
LID
10.0 - 12.0
Red -Brown SANDY SILT (ML), fill
30
42
12
52.7
0.0
47.3
22.2
30.5
2.646
1.68E-05
Ash Basin
Shelby Tube
LID
20.0 - 22.0
Tan -Brown SILTY SAND (SM), fill
NP
32
NP
28.7
0.0
71.3
23.5
5.2
2.643
1.12E-04
HDR
Dam
AB-1 S
Shelby Tube
LID
32.0 - 34.0
Tan -Brown SILTY SAND (SM), fill
31
36
5
49.7
1.8
48.5
29.7
20.0
2.655
Sonic
Jar
20.0 - 22.0
Orange -Brown CLAYEY SILTY SAND, fill
27.9
44.0
1.5
54.5
29.6
14.4
Sonic
Jar
25.0 - 27.0
Red -Brown SANDY CLAYEY SILT, fill
24.1
53.2
0.4
46.4
32.5
20.7
AB-2D
Sonic
Jar
35.0 - 37.0
Red -Brown SILTY SNAD, fill
20.8
45.3
0.2
54.5
29.5
15.8
Sonic
Jar
40.0 - 42.0
Tan -Brown SILTY SAND, fill
21.1
50.4
0.0
49.6
25.7
24.7
Notes:
* Refer to corresponding laboratory test data sheets for test results
** The data shown in this table is representative of material within the limits of impountment.

AECOM
November 26, 2019
Table 10-1: Marshall Steam Station Regulatory Permits, Approvals,
or Requirements for Ash Basin Closure by Excavation
Existing
Permit/Approval
Regulating
General Permit Name or Subject
Permit No.
Type of Regulatory Approval
Comments
Agency
(if applicable)
Mechanism or Not Required
Permit modification likely needed due to the increased
Permit Modification Likely
Air Quality
NCDEQ
heavy equipment vehicle traffic and potential dust
Required
generated during closure activities
Catawba
A local building permit is required for installation of
Building Permit
New Permit
County
construction trailers
Modification or abandonment of CAMA program
CAMA Monitoring Plan
NCDEQ
Written NCDEQ DWR approval
monitoring wells require the approval of the Division of
Water Resources (DWR)
CCR Impoundment Closure
US EPACCR
Self Regulating
Rule
CCR Impoundment Monitoring
US EPA
Maintain CCR GW monitoring network and
Self Regulating
Network
CCR Rule
requirements as stated in 257.90 - 257.98
USACOE
Individual Permit likely
Jurisdictional Areas impacts associated with Ash Basin
Clean Water Act 401
NCDEQ
required
Closure
USACOE
Individual Permit likely
Jurisdictional Areas impacts associated with Ash Basin
Clean Water Act 404
NCDEQ
required
Closure
Closure Plan
NCDEQ
Approval by Letter
See permitting for sedimentation/erosion control,
USACOE
Permit associated with other
Threatened or Endangered Species, and Wetlands. Tree
Cutting Trees
NCDEQ
permits likely
cutting could be covered under some or all of these
permits.
Permitting is required to modify or abandon wells and
Certificate of Approval to
instrumentation on regulatory dams through the
Dam Safety
NCDEQ
CATAW-0S4
Modify
Division of Energy, Mineral, and Land Resources
(DEMLR)
Ash Basin Dam - Permitting is required to modify the
dam in accordance with the Dam Safety Law of 1967,
Certificate of Approval to
Dam Safety
NCDEQ
CATAW-054
15A NCAS 02K.0201 (b)(2); an application must be filed
Modify
with the Division of Energy, Mineral, and Land Resources
(DEMLR)
1of4

AECOM
November 26, 2019
Utilization of or modification to state or federal
DOT - General
highways to transport CCR will require consultation or
notification to relevent DOT agency (if off -site removal is
required)
Driveway Permit
NCDOT
New Permit possible
Land disturbance activities outside of the ash basin will
exceed one acre, therefore in conformance with 15A
Erosion and Sediment Control (E&SC)
NCDEQ
New Permit
NCAC 04, an E&SC Permit is required from Land Quality
prior to commencement of construction in those areas.
Note that land disturbance includes tree clearing and
grubbing and vehicular wheel or tracking as disturbance.
Requirements set forth in the Duke Energy Catawba-
Wateree Shoreline Management Plan will be met. As
FERC (Ferderal Energy Regulatiory
required by the FERC Catawba-Wateree Project License
Commission)
FERC
Approval by Letter
P-2232, issued November 25, 2015, approval for any
placement of fill into Lake Norman will be obtained by
FERC prior to commencing closure construction
activities.
Removal from or import of material could be restricted
Fire Ants
Restriction not likely
dependant on the potential for fire ants and geographic
regions involved
Section 44-429 of the Catawba County Code of
Catawba
Ordinances, requires a Floodplain Development Permit
Floodplain Development
New Permit
prior to any development activities within FEMA
County
mapped Special Flood Hazard Areas for the Flood
Insurance Rate Maps
2of4

AECOM
November 26, 2019
MT-2 Form 1, Form 2, Form 3, and associated
documentation for the request of a Conditional Letter of
Map Revision (C-LOMR) will be completed and
submitted to the Department of Homeland Security
Floodplain Development
DHS FEMA
Floodplain Map Revision
Federal Emergency Management Agency (DHS FEMA)
prior to closure activities. Upon completion of Ash Basin
closure activities, a Letter of Map Revision (LOMR) will
be requested from DHS FEMA through submittal of the
aforementioned forms and a copy of the as -built plans.
Permits are required to construct any water supply well
Large Capacity Water Supply Well
NCDEQ
New Permit possible
or water well system with a design capacity equal to or
greater than 100,00 gallons per day - for dewatering
outside of the ash basin
Multi -State Agreement
If movement of CCR will cross state lines, multi -state
regulations might apply
NPDES (National Pollution Discharge
Modification of NPDES may be necessary if new source
Elimination System) Wastewater
NCDEQ
NC0004987
Permit modification likely
or outfall is created.
NPDES (National Pollution Discharge
Revision to existing sitewide permit or new permit may
Elimination System) Industrial
NCDEQ
NCS000548
Permit modification likely
be required for access roads, staging areas, etc.
Stormwater
NPDES (National Pollution Discharge
Permit required for temporary and permanent
Elimination System) Stormwater
NCDEQ
New Permit possible
stormwater rerouting.
Removal from or import of vegetated material could be
Noxious Weeds
restricted dependant on the vegetation and geographic
regions involved
Railroad Easement, Access, or Crossing
Construction activities adjacent to tracks/ballast or a
Permit
new railroad crossing require an agreement or permit
SPCC (Spill Prevention Control and
In accordance with the Federal Water
Countermeasure) Plan
US EPA
Modification of existing plan
Pollution Control Act (Clean Water Act) of 1974, Title 40,
Code of Federal Regulations, Part 112.
3of4

AECOM
November 26, 2019
Threatened or Endangered Species:
Federal and/or state regulations may apply including
Candidate Conservation Agreement
agency consultation and performing site -specific surveys
Avian Protection Plan(s)
US EPA
within the proper survey period (e.g., flowering period
Bird and Bat Conservation Strategies
NCDEQ
for listed plant) to determine if Threatened or
Eagle Conservation Plan
Endangered Species or their habitat exist within the
Eagle Take Permit
limits of disturbance
According to 15A NCAC 13B .1625, disturbance of any
closed landfill or permitted beneficial use facility will be
Solid Waste
NCDEQ
CCB0030
Approval by Letter
subject to approval by the Division of Waste
Management (DWM). Required for the excavation of
the Structural Fill Access Road.
4 of 4

FIGURES

i ;r
5 6 7 8 FIGURE 1 -1 REV. A
MAIL %
* 45a .. h,'alio--' '- -'I .•• it • 9.
t,,n ASBESTOS LANDFILLErn3�aarxl.* , ►�' '''' ; ry�v ,-r')_ h ry ;' t
�* O PERMIT NO. 1804
' * ♦------------------- r ----- --♦ rr� - ' f
0
ILF PHASE II DEMOLITION LANDFILL S "-'t f �'. - ,DX_
PERMIT NO. 1804 .. Gl4T rr
MAR-145 TEMPORARY t`
STORMWATER POND `
ILF PHASE III •
' . I
ILF PHASE IV
•��� ILF PHASE V
I �
- • ••�� 1804 LANDFILL
• *'� t (PHASE 11)
PERMIT NO. 1804
it Nlik
41
VK
. ' ♦ ti►�
1 _
' y
Ar
STRUCTURAL FILL f
PERMIT NO. CCB0031
•� W-dLd F
At
..q. _ T q
RSOLAR
O
AD FARM
STRUCTURAL FILL i
ACCESS ROAD«�
PERMIT NO. CCB0030
or
Ak
116 ''" 1 1
In �.
wr. _' ems,•} a
.40
fir. 'r��; r !I' .':r' ..;,—•f`�'rt' t
10)
4 # :#
ff 4. t NIYH' d
• 3fcr4 �.y„_ #' #�
V��
r f
OQ- _ B—
AL
PHASE I SOIL 1 .�
BORROW AREA s /,I ` . . -_ i •'�; .
1804 LANDFILL
# (APPROX. LOCATION)-
�'*wr (PHASE 1) I or
: 1
i ��f ♦ PERMIT NO. 1804 �_..
;', .'��, _ ,•� '� 8320 NC-150
... ,-op;
SHERRILLS FORD, NORTH CAROLINA 28673
_
I
AUXILIARY
SPILLWAY
WTS AREA
ACTIVE ASH BASIN
tpW.E. = 789.7
v7 FGD CONSTRUCTED ' *, ; f'' (SEE NOTE 2) LAKE NORMAN
m
N
T
O
3 4
ISLAND POINT ROAD
INDUSTRIAL LANDFILL
N PERMIT NO. 1812
Z I
' • Z i ILF PHASE I
WETLANDS
TREATMENT AREA
• � PRINCIPAL SPILLWAY
�.�•••� -_ ` INTAKE STRUCTURE
• tt40NPDES PERMITTED
A D
:1 i LANDFILL ,tt > OUTFACE 002
PERMIT ,tt <��y2 ,+ ASH BASIN DAM
ttt NO. 1809de
1 _ Alp,tt 0� iA t
*ti tt • �� to #''�
w tt 00 J; _
♦,� r,♦ r ,� ,, O Ar
'69
3�ti$� ; r ♦; DRY BOTTOM
♦ - ASH SYSTEM
IV
♦ LINED ♦ ♦ .. +
_ RETENTION I �t +,,+#, -_' COAL ♦; * +
BASINS _f tt ` PILE ♦ ' +
Y • - b Das-
RY FLY ASH SILOS
s _ GYPSUM AREA _ - 4 *�
• I{ • { ` e 40
�_ _ I I •, �. + �= FGD WW -
TREATMENTALkw
�p ` - SYSTEM faw
.......•..• E*
P k
-,'
OL f � - MARSHALL STEAM STATION A
-
jp
%
t .ft `t
4 A
•� ter �- i� * r '� ,• �'a _ — - . - j
do
P.
,,F r
4
0 INCHES 1 2 3 TENTHS 10 20 30 4 5 6 7
LEGEND
PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY (APPROXIMATE)
............. EXISTING SITE FEATURE (APPROXIMATE)
INDUSTRIAL LANDFILL (ILF) PHASE BOUNDARY (APPROXIMATE)
W.E. WATER ELEVATION
REFERENCES
1. THE AERIAL PHOTOGRAPH WAS OBTAINED FROM BING (MICROSOFT CORPORATION, 2018).
2. EXISTING FREE WATER ELEVATIONS WITH THE ASH BASIN REPRESENT PRE -DECANTING WATER
ELEVATIONS.
L=com
N
0 600 1200 1800
TITLE
VICINITY MAP AND SITE PLAN
MARSHALL STEAM STATION
CLOSURE BY EXCAVATION CLOSURE PLAN
CATAWBA COUNTY, NORTH CAROLINA
FOR ISSUED FOR APPROVAL
UKE
ENERGY®
S&tE6.00'
DES: MSR
DWG TYPE :. DWG
DFTR : MSR
JOB NO:60572849
CHKD: GL
rDAT77---0-4-19
ENGR: RJB
FILENAME: FIGURE 1 -1 . DWG
APPD: JB
DWG SIZE
DRAWING NO.
REVISION
GRAPHIC SCALE (IN FEET)
ANSID
22.0"x34.0"
FIGURE 1 -1
A
9
10
7n
H
C
m
m

FIGURE 3-1
REV. A
—E
—F
is,
`// LEGEND
PROPERTY BOUNDARY
ISLAND POINT ROAD
ASH BASIN WASTE BOUNDARY (APPROXIMATE)
INDUSTRIAL LANDFILL �`���`�/ /�'� \_/ �\ _____________ EXISTING SITE FEATURE (APPROXIMATE)
N PERMIT NO. 1812 // 0"
-` \ aa�1 ILF PHASE I // r// / \ \\\\ I / / \�^� a is®/ EXISTING MAJOR TOPOGRAPHIC CONTOUR
ASBESTOS LANDFILL _ —_—_ ' 1
I \ , ►C`�-- _/ PERMIT NO. 1804 / /
/' / % / �t \ . EXISTING MINOR TOPOGRAPHIC CONTOUR
A-
7? • �l I � �•�_ / •ILF PHASE II / ,,�^'' \,\ \\ \DEMOLITION LANDFILL / ' �/\ /—_�\ � �_ _/1 � �� \ \ ` 1 1 •«. \ \ I 1 \
I ► 1 / ________________
MAR-145 TEMPORARY /) , \ •t/ ><� ,/ I I PERMIT NO. 1804 INDUSTRIAL LANDFILL ILF PHASE BOUNDARY APPROXIMATE
' ,mot (ILF) (APPROXIMATE)
STORMWATER POND L_ L--- ---- -----1 - Z-- r ,
W.E. WATER ELEVATION
/ I ILF PHASE III
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\ t\ 1 1 11 l\� 1804 LANDFILL
\\� I 11Il I I 1\11 ♦ \ \\\ (PHASE II) ► I f / (/ . / / / , /I / \\ / / l/ \ \ \ �^ ./ // . , / / �-
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x I I N 11 \ \ 'i-�.,_•,/,,='\ \ I I � � \ v :�\ 1 `. `�- 1 1\ 11 1 I I \//// . \ \ \ \ \/ // 11 -- \ 1 t\ \ \' -\'-I ^
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STRUCTURAL FILL I _ / /�\__ ��/ .1 / / // 0 ` ` \ \ \ / IL \ `
�► \ / // � �,� \. \` : \ ` \ \ \ \ \ \ PHASE I SOIL � I \ \/ ►
I I PERMIT NO. CC60031 ► r / t \ Q \ \ \ I \ \ I ( BORROW AREA
\ 11 t I \ l / I 1 \ `, / / r APPROX. LOCATION
\\ 1\I I I 1 !'\�11t i- '� i1'1III \\ \) /•/; ` 1\ ( )
ojlil\♦ 1804 LANDFILL
\ \ � \\\ \\V/ 11, 1 PHASE I ► \ \ \ \ ` \ --,_ — \ �.
/ \ i\ \\ I 1 \ .r PERMIT NO. 1804It It
\ \�.�il� � .c \ 111 /r '• / 1 \ \ I �� `\ I • \ \ / � 1 1 \ 1 \
_ •��t \c �► 1
STEAMI ° �u,�1\
1
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ANT , I III SOLAR , 11, tj /'' \_� 1 ) \ / \ t r r� \ ► \ \\ \ \ `\ \�. l / ��„/ ► \
ROAD
FARM
If
♦�{I \_\ `� \ \ AUXILIARY "i
I STRUCTURAL FILL I ) 1 i 1 I I /// , I11 /� . n � �` \\ \ \\
ACCESS ROAD ,`�_—t __ , _ , it .//r \\�\ SPILLWAY ` 1:
PERMIT NO. CCB0030 I� J\, i \ // .. t / 1 // //�
JAI
10
FGD CONSTRUCTED
t r'� WETLANDS
(n TREATMENT AREA
�i► 1 \ r� FGD �\ \� ;,�—` i,: /=�\ , J
\ \'� � •LANDFILL \` ` ✓' tom^ ► � —�'
� \\ • \ '��\� � PERMIT � �`� \ � `y \ /' �
NO. 1809Mv
�h\�
goo
i
1'
N
i �) OZ
,\J / V LINEI'
r—
�, RETENTIONi_—
BASINS
I I r 1 ! \R
•
J far ♦
� \ Y
/ _N
—
/
GYPSUM AREA \
—� COAL
PILE
it , A l
ACTIVE ASH BASIN
W.E. = 789.7
(SEE NOTE 2)
i�
r
ti DRY BOTTOM
<\ / ASH SYSTEM j
OW, 11
x •,�
1
�
L
11
''�. ��;.
• �
r%:.ri�`��V,1�.'G�
i�`�lL:li�'�����/✓i\
\\\`%..;�1/fli;�
/ ♦ , WTS AREA
LAKE NORMAN
758.9
PRINCIPAL SPILLWAY j
f i INTAKE STRUCTURE
NPDES PERMITTED /
OUTFALL 002
ASH BASIN DAM
DRY FLY ASH SILOS
FGE WW I
TREATMENT
SYSTEM
-t\►III � r r , \��
AIr1TCC%
1. BASIS OF BEARINGS: NC GRID NAD83/2011. ELEVATIONS ARE BASED ON NAVD88.
2. WATER SURFACE ELEVATION WILL VARY DUE TO ONGOING DECANTING PROCESS.
REFERENCES
1. THE EXISTING SURVEY INFORMATION (TOPOGRAPHY, PLANIMETRICS, ETC.) IS BASED ON THE
TOPOGRAPHIC SURVEY PERFORMED BY WSP IN APRIL 2014 AND SUBMITTED TO DUKE ENERGY IN JULY
2015, AS WELL AS AN ADDITIONAL TOPOGRAPHIC SURVEY PERFORMED BY WSP IN JANUARY 2016. IT
WAS FURTHER SUPPLEMENTED BY THE MARSHALL STEAM STATION ACTIVE ASH BASIN DAM, PRINCIPAL
SPILLWAY REPLACEMENT AND AUXILIARY SPILLWAY MODIFICATION RECORD DRAWINGS, DATED
NOVEMBER 11, 2016, BY THE EXISTING DAM TOPOGRAPHIC SURVEY AS -BUILT DRAWINGS SUBMITTED
BY ESP TO DUKE ENERGY ON AUGUST 20, 2015, AND BY THE MARSHALL 2018 ANNUAL SURVEY, DATED
MAY 8, 2018.
2. WATER ELEVATIONS PRESENTED IN THIS FIGURE ARE BASED ON THE TOPOGRAPHIC SURVEY
PERFORMED BY WSP IN APRIL 2014 AND SUBMITTED TO DUKE ENERGY IN JULY 2015.
3. THE ASH BASIN WASTE BOUNDARY, THE PERIMETERS OF THE 1804 LANDFILL (PHASES I AND II),
STRUCTURAL FILL, FGD LANDFILL, ASBESTOS LANDFILL, AND DEMOLITION LANDFILL PRESENTED IN
THIS FIGURE ARE BASED ON THE "2018 COMPREHENSIVE SITE ASSESSMENT UPDATE," PREPARED BY
SYNTERRA FOR DUKE ENERGY AND SUBMITTED TO NCDEQ (NPDES PERMIT NO. NC0004987) ON
JANUARY 31, 2018.
4. PROPERTY BOUNDARIES AND THE EXTENTS OF LAKE NORMAN PRESENTED IN THIS FIGURE ARE BASED
ON THE CATAWBA COUNTY GIS, THE TOPOGRAPHIC SURVEY PERFORMED BY WSP IN APRIL 2014 AND
SUBMITTED TO DUKE ENERGY IN JULY 2015, AND THE "BOUNDARY SURVEY OF PROPERTY TO BE
ACQUIRED FROM DELMAR SHERRILL AND GEORGE C. SHERRILL" DATED JANUARY 27, 2016.
5. THE PERIMETER OF THE STRUCTURAL FILL ACCESS ROAD PRESENTED IN THIS FIGURE IS BASED ON
THE "MARSHALL STEAM STATION STRUCTURAL FILL CLOSURE REQUIREMENT AND RECORDATION
(RECORD NUMBER: 006021 MS)" LETTER SUBMITTED TO THE NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT, HEALTH AND NATURAL RESOURCES BY DUKE POWER ON JULY 8, 1998.
6. THE PERIMETER OF THE INDUSTRIAL LANDFILL PRESENTED IN THIS FIGURE WAS PROVIDED BY DUKE
ENERGY.
0 600 1200 1800
GRAPHIC SCALE (IN FEET)
AECOM
TITLE
EXISTING ON -SITE LANDFILLS AND
STRUCTURAL FILLS
MARSHALL STEAM STATION
CLOSURE BY EXCAVATION CLOSURE PLAN
CATAWBA COUNTY, NORTH CAROLINA
FOR ISSUED FOR APPROVAL
DUKE
�. ENEIGY®
S(5 @Q'
DES:
MSR
DWG TYPE:.DWG
DFTR:
JMW
JOB NO:60572849
CHKD:
GL
DATE: 10-4-19
ENGR:
RJB
FILENAME:
FIGURE 3 -1 . DWG
APPD:
JAB
DWG SIZE
DRAWING NO.
REVISION
ANSI
22.0"x34.0"
FIGURE 3-1
A
mmm
C-
I --I
C
m
W
L
m
0 INCHES 1 2 3
TENTHS 10 20
d
30
10
I

APPENDICES