Cliffside_Unit 5_ClosureOptionsAnalysis_20181114

Rogers Energy Complex – Cliffside Steam Station Unit 5 Inactive Ash Basin
Closure Options Evaluation
Summary Report

This summary report (Report) presents the Closure Options Evaluation for the Duke Energy Carolinas'
Rogers Energy Complex (Cliffside Steam Station) Unit 5 Inactive Ash Basin, located at 573 Duke Power
Road, Mooresboro, Cleveland County, North Carolina. The Closure Options Evaluation involved
developing and evaluating ash basin closure options relative to one another to determine which option
to advance to detailed engineering and closure plan development. The strategies discussed in the
Closure Options evaluation are representative of the range of possible approaches for basin closure, and
do not constitute final closure plans as described in N.C. Gen. Stat. sec. 130A-309.214(a)(4). Final
closure plans will be submitted in 2019, as required by law, supported by detailed engineering designs
and any necessary updates to groundwater modeling and related analysis.
Duke Energy developed programmatic guidance for the closure evaluation effort in early 2016 to
promote fleet-wide consistency in developing ash basin closure plans. Duke Energy developed a relative
weighting and scoring system with input from the National Ash Management Advisory Board. Using this
system, Duke Energy evaluated and scored the options using an options analysis framework designed to
identify the option that balances environmental protection, cost, schedule and local community
impacts. It is noted that internal working draft versions of these 2015-2016 Options Analyses for Allen,
Belews Creek, Cliffside, Marshall, Mayo, and Roxboro were provided to the North Carolina Department
of Environmental Quality (NCDEQ) at its request in May and June 2018.
The 2016 internal working draft Options Analyses identified Closure-in-Place as the preferred solution
for Cliffside Unit 5 Inactive Ash Basin that is protective of the environment, safely closes the ash basin,
reduces the other associated risks, and was the least cost to customers. A permit-level design was
developed for that option in 2016. Duke Energy then paused that work, pending determination that the
site would meet the requirements for a low-risk impoundment classification pursuant to the North
Carolina Coal Ash Management Act (CAMA), as amended by House Bill 630. Duke Energy has completed
those requirements at the Cliffside Unit 5 Inactive Ash Basin site for a low-risk classification and now has
updated this analysis.
SITE BACKGROUND
Duke Energy owns and operates the coal-fired Rogers Energy Complex, located in Mooresboro, in
Rutherford and Cleveland Counties, North Carolina. The Station is located on the Broad River
approximately 55 miles west of Charlotte and about 1.5 miles south of the town of Cliffside, North
Carolina. The power plant is situated on the south side of the Broad River and straddles the
Cleveland/Rutherford County line. The Station began construction and initial operations in 1939 and
1940 with Units 1-4. Unit 5 began operations in 1972, followed by Unit 6 in 2012. Units 1-4 were retired
from service in 2011 as part of the Station decommissioning and demolition program, and the Units 1-4
building was imploded in October 2015. Currently, only Units 5 and 6 continue to operate with a
combined capacity of approximately 1,387 megawatts.

Summary – Page 2

The Rogers Energy Complex ash management facilities include the Unit 5 Inactive Ash Basin, the Active
Ash Basin which includes an ash stack area, Ash Storage Area 1, and the on-site landfill. The ash in the
Units 1-4 Ash Basin has been excavated and placed in the on-site landfill, and this area has been
repurposed for stormwater and plant process water basins. Discharge from the Active Ash Basin is
permitted by the NCDEQ Division of Water Resources under the National Pollutant Discharge
Elimination System Permit NC0005088.The plant location and layout of ash management facilities are
shown on Figure 1.
The Unit 5 Inactive Ash Basin is located on the western portion of the site, west and southwest of coal-
fired Unit 5 and Unit 6. The main dam (State ID RUTHE-070) and saddle dam (State ID RUTHE-072) are
the principal embankments which form the Unit 5 Inactive Ash Basin. The main dam is approximately
1,460 ft long at the crest and the saddle dam is approximately 590 feet long at the crest. A smaller, non-
regulated containment berm exists along the eastern border of the ash basin adjacent to the plant
access road and is referred to as the Roadway Embankment. The ash basin dams were constructed in
1969 and 1970 in advance of Unit 5 operations. The ash basin received sluiced ash from Unit 5 starting
in 1972 until it was retired in 1980 when it reached capacity. The ash basin currently receives
stormwater from a localized drainage area. A majority of the eastern side of the basin is currently used
as a lay down yard for equipment and materials from the demolition of the former Units 1-4 steam
plant.
Figure 1 below presents the Unit 5 Inactive Ash Basin and other related site features.

Summary – Page 3

Figure 1. Inactive Unit 5 Ash Basin and Related Site Features
CLOSURE OPTIONS
For the Unit 5 Inactive Ash Basin, under the direction of Duke Energy, Wood Environment &
Infrastructure Solutions, Inc. (Wood) developed the following conceptual closure options that remain
under evaluation:
• Option 1: Closure-in-Place
• Option 2: Closure-by-Removal
Option 1 consists of closing the ash basin by grading the ash deposits for proper drainage, and then
closing it with an infiltration barrier/cap system meeting the requirements of the Federal Coal
Combustion Residuals (CCR) Rule and N.C. Coal Ash Management Act (CAMA). This option is
represented by the attached Figure A1.

Summary – Page 4
Option 2 consists of closing the ash basin area by removing all the ash to the onsite CCP Landfill. The
existing landfill would be expanded with a base liner system and an infiltration barrier/cap system
meeting the requirements of the Federal CCR Rule and CAMA to provide the necessary capacity. The
scope also includes removal and disposal of one foot of residual soil/sediment material within the Unit 5
Inactive Ash Basin footprint. This option is represented by the attached Figure A2.
A hybrid closure-in-place option was considered but was not included as the geometry of the Unit 5 ash
basin makes excavating the deposited ash against the dam impractical with limited remaining area
available for the consolidation.
Tables 1, 2, and 3 of this report present a tabulated summary of each evaluated closure option,
estimated quantities of ash and soil materials associated with each closure option, and a more detailed
overview of each closure option presented.
Attachment A of this report includes figures to support conceptual review and scope development for
each closure option as follows:
• Figure A1 – Option 1 Closure-in-Place
• Figure A2 – Option 2 Closure-by-Removal

Attachment B includes rough order of magnitude (ROM) cost estimates for each closure option.
Attachment C contains the scoring matrix which summarizes the composite scores of the various closure
options, the assumptions of which are outlined in Table 3 for each particular option.
METHODOLGY
A scoring matrix was prepared to consistently evaluate closure options for each of the various site
locations. This scoring evaluation matrix is included in Attachment C and considers the following
primary criteria:
• Environmental Protection and Impacts
• Cost
• Schedule
• Regional Factors
• Constructability
Rough Order of Magnitude Costs
ROM Class 5 cost estimates were prepared for each of the closure options, based on information and
quantities estimated by Duke Energy and developed during the conceptual design activities. The
estimated costs include construction, permitting, engineering design, post-construction operations and
maintenance, and groundwater monitoring. A tabulated summary of the preliminary closure cost
estimates for the options considered is presented below:

Summary – Page 5
Summary of Current ROM Cost Estimates
Closure Option Option Description
Total
Estimated
Cost
Estimated
Post-Closure
Maintenance
Cost
Option 1 Closure-in-Place $31,755,682 $30,698,670
Option 2 Closure-by-Removal $70,746,734 $1,981,206

As indicated by the cost estimate summary, Option 1: Closure-in-Place has the lowest total estimated
cost, which is primarily attributed to the additional cost for dewatering, ash excavation, ash hauling, and
landfill development associated with Option 2: Closure-by-Removal. In addition, the Closure-by-
Removal Option has additional costs of landfill development. Detailed, tabulated ROM cost estimates
are included in Attachment B.
Schedule
Within the scoring evaluation, estimates of the length of time required to initiate closure activities and
the anticipated construction duration are considered for each option.
Option 1 - Close-in-Place is estimated to take 30 months or 2.5 years. Option 2 - Closure-by-Removal is
estimated to take 46 months or 3.8 years.
A major driver in the estimated construction durations is the assumed material excavation/movement of
1,000,000 CY/year; therefore, the Closure-by-Removal option has a longer construction duration, due to
the requirement to move all ash materials, compared to the Closure-In-Place option where material
movement quantities are less. Another driver is the assumed capping rate of 50 acres/year for
completing the closure system for the Hybrid and Closure-In-Place options.
Evaluation Criteria
This Options Analysis was developed as a decision-making tool in selection of closure options when
multiple methods are allowed under applicable regulations. The intent was to develop a decision
framework that used weighting factors to balance environmental factors, cost, and the safety of workers
and the public. The Options Analysis incorporates Duke Energy’s obligation as a public utility to ensure
that its closure decisions are protective of the environment and communities, while also being prudent
from a cost-effectiveness perspective.
The analysis considered multiple aspects within each criterion, including surface water impacts,
groundwater impacts, air emissions, greenfield disturbance, construction duration, imported soil needs,
transportation and noise impacts, stormwater management, long-term maintenance needs and post-
closure monitoring.
These elements were combined to calculate a weighted sum for each criterion using the following
weights: environmental considerations (30%), cost (35%), schedule (15%), regional/community factors

Summary – Page 6
(15%) and constructability (5%). Duke Energy placed primary emphasis on environmental factors and
cost, which were approximately equal in weight. When considering all of the criteria and associated
weightings, the environmental considerations have a slightly higher weight than cost with the inclusion
of certain regional/community factors (transportation impact, noise impact, view impact) which are
effectively environmental considerations.
The scoring matrix, provided in Attachment C, scores each option on a scale of 0 (least favorable) to 10
(most favorable) for each of the specified criteria. The scores for each option are then summed based
on specified criterion weighting, resulting in an overall weighted score for each option. The results of
the scoring evaluation for the Unit 5 Inactive Ash Basin closure options are summarized in the following
table:
Summary of Closure Options Evaluation Scoring
Criterion

Option
1 Closure-in-
Place
2 Closure-by-
Removal
Environmental Protection and Impacts 2.6 2.7
Cost 2.8 0.7
Schedule 1.1 0.5
Regional Factors 1.4 1.4
Constructability 0.4 0.2
Total Score 8.3 5.4

DISCUSSION
The Options Analysis finds relatively similar rankings for environmental protection and impacts which
consider groundwater impacts, surface water impacts, air emissions based on miles driven and
avoidance of greenfield disturbance.
The analysis incorporates the latest groundwater modeling for the Unit 5 Inactive Ash Basin that
demonstrates groundwater near the basin responds similarly for several decades in all closure options
evaluated. In most cases, current boron levels are below the state groundwater standard. Long-term
modeling for both the Closure-By-Removal and Closure-In-Place scenarios do not indicate the presence
of a boron plume above standard.
The most effective step to improve groundwater is to safely decant the free water from the ash basin,
which will occur in any closure approach.
In terms of the duration of work and closure time, the Closure-In-Place scenario is expected to be
completed in 2.5 years, compared to the Closure-By-Removal option which is expected to take 3.8 years.

Summary – Page 7
Both options could be completed before the CAMA deadline of 2029 assuming work is initiated before
2023.
Other aspects the company considered are regional impacts to the surrounding community related to
traffic and noise generated by each of the options. Traffic to and from the site will occur through the
duration for each option noted above. That will include workers, trucks for deliveries or movement of
soil, topsoil, stone, geosynthetics. For the Closure-In-Place option (#1) and Hybrid option (#3) traffic will
be mingled with typical traffic on the main roads leading to Cliffside. At the Cliffside site, the active on-
site landfill is located within the Station limits so access using a public highway is not required for the
Closure-By-Removal option. The noise generated for each the options would be similar to someone near
the site, but the duration of the work and the exposure to that noise varies directly with the time
required for each option and would be longer for Closure-by-Removal. Along with increased duration
and truck trips comes higher levels of emissions for the Closure-by-Removal option as well.
The Closure-By-Removal is more than two times the estimated capital cost of the Closure-In-Place
option, and causes other unnecessary community impacts with little compelling environmental benefit.
CONCLUSION
Based on the conceptual designs for the selected closure options and evaluation of the criteria
established (environmental protection/impacts, cost, schedule, regional factors and constructability),
Closure-In-Place was identified as the option that best balances the various considerations associated
with basin closure.
ATTACHMENTS
• Table 1 – Closure Option Summary (Identification of Options)
• Table 2 – Estimated Quantity Summary
• Table 3 – Closure Options Detail Descriptions
• Attachment A – Figures and Reference Drawings
• Attachment B - Rough Order of Magnitude (ROM) Cost Estimates
• Attachment C – Closure Options Evaluation Scoring Matrix

Table 1 – Unit 5 Inactive Ash Basin Closure Options Summary
Ash Basin Closure Options Evaluation
Rogers Energy Complex – Cliffside Steam Station
Duke Energy

1

Option Description
1. Closure-In-
Place

Option 1 consists of leaving the ash material within the Ash Basin, which would
be capped with an infiltration barrier/cap system meeting the requirements of
the Federal Coal Combustion Residuals (CCR) Rule and N.C. Coal Ash
Management Act (CAMA). The scope also includes modification of the Main
Dam for stormwater discharge, Saddle Dam for access, and regrading of the
overburden area at the west of the basin to drain positively without piping.

2. Closure-by-
Removal

Option 2 consists of excavating all ash material and a 1-ft thick soil layer within
the limits of the Unit 5 Inactive Ash Basin and placing the material in the existing
on-site permitted industrial landfill located south of the Unit 5 Inactive Ash Basin.
This industrial landfill would be expanded and constructed with a base liner
system and an infiltration barrier/cap system meeting the requirements of the
Federal CCR Rule and CAMA.

1

Table 2 – Unit 5 Inactive Ash Basin Quantity Summary
Ash Basin Closure Options Evaluation
Rogers Energy Complex - Cliffside Station
Duke Energy

Item Volume Units Area
(Acres)
Existing Ash
Ash Basin Area (regulatory boundary) NA 60.5
In Place Ash Volume 1,960,000 CY 60.5
Ash Basin Dam Soil Volume 450,000 CY NA
Option 1: Closure-in-Place
Ash Volume in Final Closure Footprint 1,960,000 CY 60.5
Ash Regrading 234,600 CY NA
Dam Soil Cut Volume 92,473 CY NA
Soil Needed (18” Cover Soil) 116,200 CY 60.5
Offsite Topsoil Needed (6” for Final Cover) 38,720 CY 60.5
Option 2: Closure-by-Removal
Ash Excavation Volume (Excavated Area) 1,960,000 CY 60.5
Over Excavation Volume (1 ft.) 97,600 CY 60.5
Dam Soil Cut Volume 450,000 CY NA
Soil Needed (Onsite Landfill: 1.5’ Soil for Closure
Cap) 46,000 CY 19.0
Offsite Topsoil Needed (6” over Closure-by-Removal
Area and Onsite Landfill Closure Cap) 64,130 CY 79.5
*Volumes will be determined as part of the final design if the respective option is selected as the closure
option.

Table 3 – Unit 5 Inactive Ash Basin Closure Option Detail Descriptions
Ash Basin Closure Options Evaluation
Rogers Energy Complex - Cliffside Station
Duke Energy

1

Option Description
1. Closure-In-
Place
Closure-In-Place consists of grading and covering the ash within the Unit 5
Inactive Ash Basin footprint with a final cover system. This closure option
assumes ash will be permanently contained in the final Unit 5 Inactive Ash
Basin footprint. The estimated volume of ash moved for closure is 234,600 cy.
The Unit 5 Inactive Ash Basin Main Dam will be breached to allow stormwater
flow to discharge into the Broad River.
The following reference drawing represents this option:
• Figure A1 – Option 1 – Closure-In-Place
Environmental Protection and Impacts Considerations
• Estimated quantities used for cost estimates are summarized in Table
2.
Cost Considerations
The total estimated construction cost is $31,755,682, and the estimated post-
closure O&M cost (30 years) is $30,698,670.
Schedule Considerations
The total estimated closure duration is estimated at 30 months. Construction
duration is estimated at 14 months, and the time to start ash removal is
estimated at 16 months.
Regional Factors
• None of the closure footprint could be reused without consideration of
cover system after completion of closure.
• The requirements for imported soil are included in Table 2.
• There are currently no plans for beneficial reuse of ash after closure.
• Noise impact considered lowest for Closure-In-Place due to smallest
amount of material moved.
• View impact considered lowest for Closure-In-Place due to shortest
closure height.

Table 3 – Unit 5 Inactive Ash Basin Closure Option Detail Descriptions
Ash Basin Closure Options Evaluation
Rogers Energy Complex - Cliffside Station
Duke Energy

2

Option Description
Constructability
• In place closure has highest overall score for constructability due to
reduced grading, reduced impact to the plant operations, and reduced
additional equipment (truck wash, equipment for double handling, etc.).
• In place closure has constructability and feasibility benefits utilizing
existing embankments for containment and erosion and sedimentation
control and management.

2. Closure-By-
Removal
Closure-By-Removal is based on removing ash from within the limits of the
Unit 5 Inactive Ash Basin and permanently placing it in an expansion of the on-
site permitted and lined landfill area located at Duke Energy’s Rogers Energy
Complex. The estimated volume of ash removed/hauled for closure is
1,960,000 cy, and the estimated volume of residual soil removed/hauled is
97,600 cy. For this option, the Unit 5 Inactive Ash Basin Main Dam and Saddle
Dam will be breached/removed to allow stormwater flow to discharge into the
Broad River.
The following reference drawings represents this option:
• Figure A2 – Option 2 – Closure-By-Removal
Environmental Protection and Impacts Considerations
• Estimated quantities used for cost estimates are summarized in Table
2.
Cost Considerations
The total estimated construction cost is $70,746,734, and the estimated post-
closure O&M cost (30 years) is $1,981,206.
Schedule Considerations
The total estimated closure duration is estimated at 46 months. Construction
duration is estimated at 30 months, and the time to start ash removal is
estimated at 16 months.

Table 3 – Unit 5 Inactive Ash Basin Closure Option Detail Descriptions
Ash Basin Closure Options Evaluation
Rogers Energy Complex - Cliffside Station
Duke Energy

3

Option Description
Regional Factors
• Ash basin closure area could be reused without consideration of cover
system after completion of excavation.
• The topsoil needs for both options assume an offsite source is needed
requiring import for the topsoil volume.
• There are currently no plans for beneficial reuse of ash after closure.
• Noise impact considered highest for removal and landfill option due to
largest amount of material moved resulting in lowest scoring.
• View impact considered highest for removal and landfill options
resulting in lowest scoring due to the height of the landfill and proximity
to public roads.
Constructability
• Requires development of new landfill space to accommodate all ash
removal.
• Closure-By-Removal scores lower in constructability due to amount of
additional equipment required to move and handle material including
equipment for double handling, truck wash, additional plant traffic,
overall amount of material to move, and increased exposure for erosion
and sedimentation control with embankment removal.

ATTACHMENTS

Attachment A – Figures and Reference Drawings

A.060C.060A.060C.060B.060B.060D.060D.060E.060E.060CSE CSECSECSECSECSECSECSECSECSECSECSECSE CSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSECSE
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COVER SYSTEM EXTENTS (TYP.)BROAD RIVER
1.070FINAL COVER SYSTEM (TYP.)5.2:13.0:19.14%7.50%9.33%9.93%
9.15%EXISTING GROUTED ANDABANDONED IN PLACE 36" RCP800
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770780
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APPROXIMATE LIMITS OF ASHBASIN UNIT BOUNDARYAPPROXIMATE LIMITS OF CCRBOUNDARYADDITIONAL FLOW CONTROLDETAIL DESIGN TO BE DEVELOPEDPRIOR TO CONSTRUCTIONEXISTING EMERGENCY SPILLWAYTO BE LOWEREDTIE INTO EXISTINGSPILLWAY CHANNELADDITIONAL IMPROVEMENTSTO CHANNELS TO BEEVALUATED PRIOR TOCONSTRUCTIONSTRUCTURAL DESIGN OFSPILLWAY TO BE DEVELOPEDPRIOR TO CONSTRUCTION800 750760770780790750740
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810820 UNIT 5 INACTIVE ASHBASIN MAIN DAM(RUTHE-070)UNIT 5 INACTIVE ASHBASIN SADDLE DAM(RUTHE-072)UNIT 5 INACTIVE ASH BASINSADDLE DAM - ROADWAYEMBANKMENT (RUTHE-072)770780780776770774766768770 760756752780
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7907707807903.5:19.6:1UNIT 5INACTIVEASH BASINUNIT 5INACTIVEASH BASINCBR: VERIFICATION AREA FOR THEPRESENCE OF CCR. (SEE NOTE 2)CBR: VERIFICATION AREA FOR THEPRESENCE OF CCR. (SEE NOTE 2)SOIL/SPOIL FILL AREA.NO ASH PLACED IN THISAREA.SOIL/SPOIL FILL AREA.NO ASH PLACED IN THISAREA.CBR: VERIFICATION AREA FOR THEPRESENCE OF CCR. (SEE NOTE 2)CBR: VERIFICATION AREA FOR THEPRESENCE OF CCR. (SEE NOTE 2)0+00 1+00 2+00 3+00 4+00 5+00 6+00 7+00 8+00 9+00 10+0010+500+00 1+00 2+00 3+00 4+00 5+00 6+00 7+00 8+00
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6+00 6+50F.060F.060G.060G.060H.060H.060I.060I.060NDWG SIZEREVISIONFORDRAWING NO.TITLEFILENAME:DWG TYPE:JOB NO:DATE:SCALE:DES:DFTR:CHKD:ENGR:APPD:AFEDCB234578645789106AFCB22"x34"ANSI DSEALREVDATEJOB NO.PROJECT TYPE DES DFTR CHKD ENGR APPDDESCRIPTIONDMSDMSKKKKKK.DWG6057792411-16-2018AS NOTED032N.C. ENGINEERING LICENSE NO.F-0342OPTION 1 - CLOSURE-IN-PLACEUNIT 5 INACTIVE ASH BASIN CLOSURE PLANROGERS ENERGY COMPLEX - CLIFFSIDE STEAM STATIONFOR REVIEW ONLY - NOT ISSUED FOR CONSTRUCTIONCLS.C901.002.040.DWGFIGURE A100FIGURE A1FIGURE A1NOTE:1. CLOSURE-IN-PLACE IS PROPOSED WITHIN THE FINAL COVER LIMITS (COVER SYSTEM EXTENTS).2. CLOSURE-BY-REMOVAL AREA BETWEEN COVER SYSTEM EXTENTS AND APPROXIMATE LIMITS OF ASH BASINUNIT BOUNDARY IS CONSIDERED TO BE AN AREA WHERE SPOIL AND SOIL FILL WAS PLACED BASED ON PLANTOPERATIONAL INFORMATION FROM DUKE ENERGY. THE HISTORICAL PRE-DEVELOPMENT BASE GRADEELEVATIONS OF THESE AREAS ARE GENERALLY ABOVE THE HISTORICAL MAXIMUM ELEVATION OF THE STOPLOG OF THE RISER STRUCTURE AND THE DAM ELEVATION. DUKE ENERGY BELIEVES THERE IS NO CCR IN THISAREA. THEREFORE, AECOM IS PROPOSING A SOIL SAMPLING PLAN USING DRILLING TO EVALUATE THEPRESENCE OF ASH BELOW THE FILL, CONSISTENT WITH THE EXCAVATION SOIL SAMPLING PLAN PREPARED BYDUKE ENERGY FOR CLOSURE-BY-REMOVAL AREAS AND INCLUDED AS APPENDIX E TO THE CLOSURE PLAN. IFVISIBLE ASH IS NOT DISCOVERED, THEN THE COVER SYSTEM WILL REMAIN AS SHOWN. IF THE PRESENCE OFASH IS DISCOVERED, THE ASH WILL BE EXCAVATED AND PLACED WITHIN THE PROPOSED COVER SYSTEMEXTENTS AND FILL TO THE DESIGNED GRADES USING CLEAN SOIL, ESPECIALLY IN LOCATIONS WHERE ASH MAYBE PRESENT AT SHALLOW DEPTHS ONLY.3.THE “APPROXIMATE LIMITS OF ASH BASIN UNIT BOUNDARY” AND THE “APPROXIMATE LIMITS OF CCR BOUNDARY”WERE DEVELOPED BY AMEC AND ADOPTED BY AECOM. THESE BOUNDARIES ARE BASED ON AERIALPHOTOGRAPHY, TOPOGRAPHIC MAPPING, AND OTHER HISTORICAL DRAWINGS AND INFORMATION AND SHOULDBE CONSIDERED APPROXIMATE. THE “APPROXIMATE LIMITS OF ASH BASIN UNIT BOUNDARY” INCLUDES THECONTAINMENT DAMS AND DIKES WHILE THE “APPROXIMATE LIMITS OF CCR BOUNDARY” EXCLUDES THOSESTRUCTURES AND IS BASED ON UPDATED TOPOGRAPHIC MAPPING, REPORTED OPERATIONAL LEVELS, ANDSUBSURFACE DATA COLLECTED WITHIN THE BASIN. IT SHOULD BE NOTED THAT THE DETERMINATION OF THEACTUAL LATERAL EXTENT OF THE CCR MATERIALS WILL TAKE PLACE PRIOR TO, AND/OR DURING,IMPLEMENTATION.4. THE PROPOSED 5(H):1(V) SLOPES FOR EXCAVATIONS IN SATURATED SLUICED ASH IS THE MAXIMUM SLOPEALLOWABLE BASED ON THE CURRENT LEVEL OF DESIGN. THIS DESIGN ELEMENT WILL BE FURTHER REFINEDDURING THE FINAL CONSTRUCTION-LEVEL DESIGN TO EVALUATE CONSTRUCTION SEQUENCE/PHASING,DURATION THE EXCAVATION AREA MAY REMAIN OPEN, DEWATERING REQUIREMENTS, INSTRUMENTATION ANDMONITORING APPROACHES, ACTUAL CONDITIONS OF SLUICED ASH AT THE LOCATION OF THE EXCAVATION,AND OTHER RELATED STABILITY AND SAFETY CONSIDERATIONS. THE CONSTRUCTION CONTRACTOR WILL BEREQUIRED TO PROVIDE A DEWATERING AND MONITORING PLAN PRIOR TO EXCAVATION TO VERIFY THAT THEPROPOSED EXCAVATION MEETS THE MINIMUM FACTORS OF SAFETY FOR THE CONDITIONS MODELED.5. ASH FILL AND STACK AREAS WILL BE COMPACTED TO 90% OF THE MAXIMUM DRY DENSITY OR GREATER.6. FINAL COVER GEOMEMBRANE AND COVER SYSTEM GRADES MUST BE INSTALLED WITH AN ADEQUATESEPARATION BETWEEN THE MEMBRANE AND GROUNDWATER SUCH THAT DEVELOPMENT OF GROUNDWATERPRESSURE UNDERNEATH THE COVER SYSTEM IS MITIGATED. AN UNDERDRAIN SYSTEM IS BEING MODELED BYOTHERS FOR DUKE ENERGY AND A DETAIL DESIGN WILL BE DEVELOPED PRIOR TO CONSTRUCTION.REFERENCES:1. EXISTING TOPOGRAPHIC INFORMATION WAS PRODUCED FROM PHOTOGRAMMETRIC METHODS FROM AERIALPHOTOGRAPHY OBTAINED ON JULY 31, 2015 BY WSP.2. APPROXIMATE LIMITS OF CCR BOUNDARY EXTRACTED FROM INTERPRETED BOTTOM OF ASH AUTOCAD CIVIL 3DSURFACE BY AMEC. INTERPRETED BOTTOM OF ASH CONTOURS TAKEN FROM AMEC FOSTER WHEELER, WASTESTRATEGY ANALYSIS, CLIFFSIDE STEAM STATION, APRIL 17, 2015.LEGENDAPPROXIMATE LIMITS OF ASH BASIN UNIT BOUNDARYAPPROXIMATE LIMITS OF CCR BOUNDARYCOVER SYSTEM EXTENTSDUKE ENERGY PROPERTY BOUNDARYCLOSURE-BY- REMOVAL AREASPOIL/SOIL FILL AREACSE
2.5:12.5:12.5:1
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830
840
750 760 770 780790800800800810820 700700710 710 720720 730730 740740 750750 760760
780780790790800800810820830830830840850800810810810
780790800810820780790800810
780
790
800
81
0
82
0
83
0 770780790800810820830840ASSUMED CLOSURE BYREMOVAL LIMITS SHOWNASSUMED CLOSURE BYREMOVAL LIMITS SHOWNASSUMED CLOSURE BYREMOVAL LIMITS SHOWNNNC GEOLOGY: C-247NC ENG: F-1253LICENSURE:FAX: [phone]TEL: [phone]CHARLOTTE, NC 28208SUITE 1002801 YORKMONT ROAD11/7/20187810150346DWGAS SHOWNKRDJMBJMBDLJCNBUnit 5 Basin - Closure Option 2 Concept Plan.dwg000FIGURE A2FIGURE A2FIGURE A2NOT RELEASED FOR CONSTRUCTIONOPTION 2 - CLOSURE BY REMOVAL11/7/20180NOT RELEASED FOR CONSTRUCTIONKRDJMBJMBDLJCNBCIVIL DESIGN PLAN7810150346REFERENCES:1. BOTTOM OF ASH CONTOURS TAKEN FROM AMEC FOSTER WHEELER, WASTE STRATEGY ANALYSIS, CLIFFSIDE STEAM STATION, APRIL 17, 2015.2. BORING LOCATIONS, PIEZOMETER LOCATIONS, AND SEEP LOCATIONS TAKEN FROM HDR, COMPREHENSIVE SITE ASSESSMENT REPORT, CLIFFSIDE STEAM STATION ASH BASIN,AUGUST 2015 AND PHASE 2 RECONSTITUTION OF ASH POND DESIGNS FINAL REPORT, REV 1, FEBRUARY 19, 2016.3. EXISTING TOPOGRAPHIC INFORMATION WAS PRODUCED FROM PHOTOGRAMMETRIC METHODS FROM AERIAL PHOTOGRAPHY OBTAINED ON JULY 31, 2015 BY WSP.102030TENTHSINCHES123DWG SIZEREVISIONFORDRAWING NO.TITLEFILENAME:DWG TYPE:JOB NO:DATE:SCALE:DES:DFTR:CHKD:ENGR:APPD:AFEDCB234578645789106AFCB22"x34"ANSI DSEALREVDATEJOB NO.PROJECT TYPE DES DFTR CHKD ENGR APPDDESCRIPTIONABSAT ISSUE #DATEDESIGNEnvironment & InfrastructureSolutions2801 YORKMONT ROAD, SUITE 100CHARLOTTE, NC 28208TEL: [phone] FAX: [phone]LICENSURE: NC ENG: F-1253 NC GEOLOGY: C-247

ATTACHMENTS

Attachment B - Rough Order of Magnitude (ROM) Cost
Estimates

Item Description Quantity Unit Unit Cost Total Cost
Mobilization/Demobilization 1 LS 620,834 620,834$
620,834$
Abandon Outlet Structures/Piping 1 LS $160,000 160,000$
Field Surveying and Utility Location1 60.5 Acres $2,000 121,000$
281,000$
Erosion/Sediment Control and Storm Water Management 60.5 Acres $14,000.00 847,000$
Surface Water Diversions/Ditches/Swales 12,770 LF $100.00 1,276,960$
Permanent Stabilization Measures 52.8 Acres $3,787 199,954$
Armor Embankment 100,177 SF $15 1,502,655$
3,826,569$
Construction Entrance 50 LF $65 3,250$
Clearing and Grubbing 5.5 Acres $5,000 27,500$
Topsoil Stripping 9.0 Acres $4,000 36,000$
Earthwork Cut to Fill2 92,473 CY $6.87 635,290$
702,040$
Final Cover System - Subgrade Preparation 48.0 Acres $5,000 240,000$
40-mil Textured LLDPE Geomembrane 2,090,880 SF $0.42 878,170$
Geocomposite Drainage Layer3 2,090,880 SF $0.60 1,254,528$
Final Cover System - Vegetative/Protective Soil Material (24-inch thick un-compacted fill, source material from on-site 4) 154,880 CY $16.00 2,478,080$
4,850,778$
Removal and Filtration Free Water (Ash Basin)0 Mo $416,667.00 -$
Removal and Treatment of Pore Water (Ash Basin)24 Mo $583,333 13,999,992$
Hauling, Placement, and Compaction of Material (soil, pond ash, rock) to another area of Ash Pond 234,600 CY $5.00 1,173,000$
15,172,992$
25,454,212$
Closure Design/Engineering/Permitting (5% of Final Cover System Construction Costs excluding Mob/Demob)1 LS 1,241,669$ 1,241,669$
Construction Quality Assurance (CQA) (5% of Final Closure Construction Costs excluding Mob/Demob)1 LS 1,241,669$ 1,241,669$
2,483,338$
Maintenance 30 YR 81,600$ 2,448,000$
Monitoring 30 YR 941,689$ 28,250,670$
30,698,670$
Contingency (15% of Final Cover System Construction Costs)1 LS 3,818,132$ 3,818,132$
3,818,132$
Total Capital Costs 31,755,682$
Total OMM Costs 30,698,670$
62,454,352$
1,032,303.33$
Notes:
1. Includes construction stakeout, intermediate field survey, and project record drawings.
2. Regrading of embankment by grading into the former pond area following grading of the ash.
3. Geocomposite to have geotextile fabric heat-bonded to each side.
4. Sources of earthwork material is clarified as on- or off-site sources per line item.
Unit 5 Option 1 Overview: Closure-in-Place
Closure Opinion of Probable Cost
Duke Energy - Rogers Energy Complex - Cliffside Steam Station
Mooresboro, North Carolina
Earthwork
Subtotal - Earthwork
Cover System with Geosynthetics
Subtotal - Cover System Costs
Acquisition
Subtotal - Acquisition
General
Subtotal - General
Erosion/Sediment Control and Storm Water Management
Subtotal - Erosion/Sediment Control and Storm Water Management
Opinion of Probable Closure Cost Per Acre
Design, Permitting and CQA
Subtotal - Design, Permitting and CQA
Post Closure Operations and Maintenance Costs
Subtotal - Post Closure Costs
Additional Costs
Subtotal - Additional Costs
Ash Pond Dewatering, Loading, Hauling, and Placement
Subtotal - Ash Pond Dewatering, Loading, Hauling, and Placement
Total Opinion of Probable Closure Costs
Subtotal - Final Cover System Construction Costs
Item Description Quantity Unit Unit Cost Total Cost
Mobilization/Demobilization 1 LS 1,383,123 1,383,123$
1,383,123$
Abandon Outlet Structures/Piping 1 LS $160,000 160,000$
Field Surveying and Utility Location1 60.5 Acres $2,000 121,000$
281,000$
Erosion/Sediment Control and Storm Water Management 61 Acres $14,000.00 847,000$
Permanent Stabilization Measures 60.5 Acres $3,787 229,114$
1,076,114$
Construction Entrance 50 LF $65 3,250$
Clearing and Grubbing 5.5 Acres $5,000 27,500$
Breaching Main Dam 1.0 LS $1,000,000 1,000,000$
Earthwork Cut to Fill2 450,000 CY $6.87 3,091,500$
Topsoil Stripping 9.2 Acres $4,000 36,796$
Topsoil Material; if required (6-inch thick un-compacted fill, source material on-site4) 44,367 CY $10.78 478,273$
4,637,319$
Landfill Construction 19.0 Acres $400,000.00 7,600,000$
Landfill Closure 19.0 Acres $150,000.00 2,850,000$
10,450,000$
Removal and Filtration Free Water (Ash Basin)0 Mo $416,667.00 -$
Remvoal and Treatment of Pore Water (Ash Basin)24 Mo $583,333 13,999,992$
Haul Road Construction 500 LF $60 30,000$
Excavation of Pond Ash and Loading in Trucks 1,960,000 CY $8.43 16,522,800$
Excavation of Residual Soils and Loading in Trucks (1ft below bottom of ash)97,607 CY $10.00 976,067$
Hauling, Placement, and Compaction of Pond Ash and Impacted Soils to Cliffside CCP Landfill 3 2,057,607 CY $3.50 7,201,623$
Truck Wash 1 LS $150,000 150,000$
38,880,482$
56,708,037$
Closure Design/Engineering/Permitting (5% of Final Closure Construction Costs excluding Mob/Demob)1 LS 2,766,246$ 2,766,246$
Construction Quality Assurance (CQA) (5% of Final Closure Construction Costs excluding Mob/Demob)1 LS 2,766,246$ 2,766,246$
5,532,491$
Landfill Area Maintenance 30 YR 66,040$ 1,981,206$
Landfill Area Monitoring 0 YR -$
1,981,206$
Additional Costs
Contingency (15% of Final Closure Construction Costs)1 LS 8,506,206$ 8,506,206$
8,506,206$
Total Capital Costs 70,746,734$
Total OMM Costs 1,981,206$
72,727,940$
1,202,114.71$
Notes:
1. Includes construction stakeout, intermediate field survey, project record drawings and utility location.
2. Remove existing embankment by grading into the former pond area following removal of the ash and impacted adjacent and subsurface material.
3. Excavated pond ash to be hauled and placed in onsite ash landfill.
4. Sources of earthwork material is clarified as on- or off-site sources per line item.
Earthwork
Unit 5 Option 2 Overview: Removal
Closure Opinion of Probable Cost
Duke Energy - Rogers Energy Coplex - Cliffside Steam Station
Mooresboro, North Carolina
Acquisition
Subtotal - Acquisition
General
Subtotal - General
Erosion/Sediment Control and Storm Water Management
Subtotal - Erosion/Sediment Control and Storm Water Management
Total Opinion of Probable Closure Costs
Opinion of Probable Closure Cost Per Acre
Subtotal - Earthwork
Ash Pond Dewatering, Loading, Hauling, and Placement
Onsite Landfill Subtotal - Ash Pond Dewatering, Loading, Hauling, and Placement
Subtotal - Final Closure Construction Costs
Landfill
Subtotal - Landfill
Subtotal - Additional Costs
Post Closure Operations and Maintenance Costs
Subtotal - Post Closure Costs
Design and Permitting
Subtotal - Design and Permitting
ATTACHMENTS
Attachment C - Closure Options Evaluation Scoring
Matrix
Site Name: Rogers Energy Complex ‐ Cliffside Steam Station1= Option‐Specific User Input1 = Calculated ValueOption12Environmental Protection and Impacts Weight: 30%CriterionScoring SystemRequired Input Units Option 1 Option 2Option 1 Option 2 Modeled Plume Intersecting Surface WaterRefer to EM Sub‐Scoring Sheet10 1024% 7.2%Groundwater Impact Beyond the current Compliance BoundaryRefer to EM Sub‐Scoring Sheet10 1024% 7.2%Modeled Off‐site ImpactRefer to EM Sub‐Scoring Sheet10 1024% 7.2%Relative rank based on visual interpretation of modeled boron plumeRefer to EM Sub‐Scoring Sheet01013% 3.9%Air emissions off‐site (based on miles driven hauling CCR and CCR contaminated soil off‐site )Interpolation. Min value scores 10. Max value scores 0.Truck miles driven Miles000 1 10 10 5% 1.5%Air emissions on‐site (based on gallons of fuel consumed) from closure implementation Interpolation. Min value scores 10. Max value scores 0.Gallons of fuel consumed Gallons400000 2057600400000 2057600 10 0 5% 1.5%Avoidance of greenfield disturbanceInterpolation. Min value scores 10. Max value scores 0.Disturbed acres of greenfield Acres0100 10 10 0 5% 1.5%2.6 2.7CostWeight:35%Criterion Scoring System Required Input Units Option 1 Option 2Option 1 Option 2Closure Cost Closure Cost USD$31,755,682 $70,746,73431,755,682.00$            70,746,734.00$           10.0 0.0 80% 28.0%Operation, Maintenance and Monitoring Cost OM&M Cost USD$30,698,670 $1,981,2061,981,206.00$              30,698,670.00$           0.0 10.0 20% 7.0%2.8 0.7ScheduleWeight:15%Criterion Scoring System Required Input Units Option 1 Option 2Option 1 Option 2Initiation TimeTime to move first ashMonths36 3030 36 0 10 30% 4.5%Construction DurationEstimated durationsMonths14 3014 30 10 0 70% 10.5%1.1 0.5This Area Not Used For Interpretation of Environmental Modeling ResultsUnit 5 Inactive Ash Basin ClosureInterpolation. Min value scores 10. Max value scores 0.Contribution to Total ScoreValue that Scores 0DescriptionClosure‐In‐PlaceClosure‐By‐Removal: Existing On‐site LandfillInterpolation. Min value scores 10. Max value scores 0.User Input Value that Scores 10This Area Not Used For Interpretation of Environmental Modeling ResultsThis Area Not Used For Interpretation of Environmental Modeling ResultsThis Area Not Used For Interpretation of Environmental Modeling ResultsContribution to Total ScoreWeighted Totals (Contribution to Total Score)Weighted Totals (Contribution to Total Score)Value that Scores 10 Value that Scores 0User InputCriterion WeightValue that Scores 0 ulated or User Selected SWeighted Totals (Contribution to Total Score)Scoring for Evaluation of Closure OptionsDuke EnergyContribution to Total Scoreulated or User Selected S Criterion WeightUser Input Value that Scores 10ulated or User Selected S Criterion Weight1. Provide continued geotechnical stability meeting appropriate safety factors under applicable loading conditionsThreshold Criteria: All closure options must comply with the following threshold criteria based on Duke Energy Guiding Principals for Ash Basin Closure2. Provide flow capacity and erosion resistance during design storm and flooding conditions3. Effectively mitigate groundwater impacts (in conjunction with GW remediation where present)4. Comply with applicable state and federal regulations (e.g. North Carolina Coal Ash Management Act)Closure Options Evaluation Worksheet
Site Name: Rogers Energy Complex ‐ Cliffside Steam Station1= Option‐Specific User Input1 = Calculated ValueUnit 5 Inactive Ash Basin ClosureScoring for Evaluation of Closure OptionsDuke EnergyClosure Options Evaluation WorksheetRegional FactorsWeight:15%Criterion Scoring System Required Input Units Option 1 Option 2Option 1 Option 2Plan or potential for beneficial reuse of siteSubjective005% 0.8%Imported soil needsInterpolation. Min value scores 10. Max value scores 0.Soil ImportedCY000 0 10 10 5% 0.8%Beneficial reuse of CCRInterpolation. Max value scores 10. Zero value scores 0.Fraction UsedNone0.1 0.10.1 0 10 10 15% 2.3%Transportation impact (based on miles driven hauling CCR and CCR contaminated soil off‐site)Interpolation. Min value scores 10. Max value scores 0.Miles DrivenMiles000 1 10 10 65% 9.8%Noise impact due to on‐site activity (based on proximity of neighbors to on‐site work areas)Subjective 0 to 10: 10 is the least noise;0 is the most noise.10 75% 0.8%View impact (based on final height of storage facility and land uses within viewshed)Subjective 0 to 10; 10 is the least visual;0 is the most visual.975% 0.7%1.4 1.4ConstructabilityWeight:5%Criterion Scoring System Required Input Units Option 1 Option 2 Option 3A Option 3B Option 4 Option 1 Option 2Consider stormwater management, geotechnical, and dewateringSubjective 0 to 10: 10 is the least commplicated; 0 is the most complicated83100% 5.0%0.4 0.28.3 5.4User Inputulated or User Selected SContribution to Total ScoreCriterion WeightNot Used For Subjective ScoringNot Used For Subjective ScoringTotal Score For Each Option (On a Scale of 0 to 10)Weighted Totals (Contribution to Total Score)User Input Value that Scores 10 Value that Scores 0 ulated or User Selected SValue that Scores 10 Value that Scores 0Weighted Totals (Contribution to Total Score)Not Used For Subjective Scoring
Revision GCriteria for Evaluation of Closure OptionsClosure Options Evaluation WorksheetAsh Basin Closure ‐ Master Programmatic DocumentDuke EnergyCategory Criterion Guidance Modeled Plume Intersecting Surface Water Refer to scoring system on Environmental Modeling (EM) Sub‐Scoring worksheet.Groundwater Impact Beyond the current Compliance BoundaryRefer to scoring system on  Environmental Modeling (EM) Sub‐Scoring worksheet.Modeled Off‐site Impact Refer to scoring system on  Environmental Modeling (EM) Sub‐Scoring worksheet.Relative rank based on visual interpretation of modeled boron plume Refer to scoring system on  Environmental Modeling (EM) Sub‐Scoring worksheet.Air emissions off‐site Based on truck miles driven off‐site for hauling CCR and CCR contaminated soil.Air emissions on‐site from closure implementation Based on total cubic yards of cut and fill on site as a surrogate for gallons of fuel consumed.Avoidance of greenfield disturbance Refer to Scoring System and Required Input columns on scoring sheet.Capital CostOperation, Maintenance and Monitoring CostInitiation TimeConstruction DurationPlan or potential for beneficial reuse of site Refer to Scoring System and Required Input columns on scoring sheet.Imported soil needs Refer to Scoring System and Required Input columns on scoring sheet.Beneficial reuse of CCR Refer to Scoring System and Required Input columns on scoring sheet.Transportation impact Based on truck miles driven off‐site for hauling CCR and CCR contaminated soil.Noise impact due to on‐site activity Based on proximity of neighbors to specific on‐site work areas.View impact Based on final height of storage facility and land uses within viewshed.ConstructabilityConsider stormwater management, geotechnical, and dewatering Subjective and relative comparison to other optionsRegional FactorsFrom rough order‐of‐magnitude cost estimate or detailed cost estimate.Threshold Criteria: All closure options must comply with the following threshold criteria based on Duke Energy Guiding Principals for Ash Basin ClosureFrom preliminary schedule for designing, permitting, bidding and constructing the option.1. Provide continued geotechnical stability under applicable loading conditions and safety factors2. Provide flow capacity and erosion resistance during design storm and flooding conditionsEnvironmental Protection and ImpactsCostSchedule3. Effectively mitigate groundwater impacts4. Comply with applicable state and federal regulations (e.g. North Carolina Coal Ash Management Act)
Environmental Groundwater Sub‐Scoring WorksheetClosure Options Evaluation Duke EnergyScored by: TH, RC, CMCriteria 1.  Modeled Plume Intersecting Surface Water ScoreModeled plume1 does not intersect surface waters after 10 years10Modeled plume1 does not intersect surface waters after 100 years5Modeled plume1 does not intersect surface waters after 200 years0(Option 1) (Option 2)Closure‐In‐Place Closure‐By‐Removal: Existing On‐Site Landfill10 10Criteria 2.  Groundwater Impact Beyond the current2 Compliance Boundary ScoreModeled plume1 is within current compliance boundary after 10 years10Modeled plume1 is within current compliance boundary after 100 years5Modeled plume1 is within current compliance boundary after 200 years0(Option 1) (Option 2)(Option 1) (Option 2)Closure‐In‐Place Closure‐By‐Removal: Existing On‐Site Landfill10 10Criteria 3.  Modeled Off‐site Impact ScoreModeled plume1 does not go off‐site 10Modeled plume1 is predicted to remain off‐site after 100 years5Modeled plume1 is predicted to remain off‐site after 200 years0(Option 1) (Option 2)Closure‐In‐Place Closure‐By‐Removal: Existing On‐Site Landfill10 10Criteria 4.  Relative rank based on visual interpretation of modeled boron plume ScoreRanked #1 among the three Closure Options based on visual interpretation of modeled boron plume  10Ranked #2 among the three Closure Options based on visual interpretation of modeled boron plume  5Ranked #3 among the three Closure Options based on visual interpretation of modeled boron plume  0(Option 1) (Option 2) Closure‐In‐Place Closure‐By‐Removal: Existing On‐Site Landfill010Note 2: The current compliance boundary is the compliance boundary found in the figure "Ash Basin Waste and Compliance Boundaries" provided to NCDEQ on 3/8/18Criteria 3 ScoreCriteria 4 ScoreNote 1: Based on avaliable data at the time of scoring, the modeled plume considered boron at a concentration of 4,000 ug/l or greater;  4,000 µg/L does not represent a remediation goal, however this concentration does represent the EPA Tap Water Regional Screening Level (RSL) in resident tapwater for boron.Rogers Energy Complex ‐ Cliffside Steam Station Unit 5 Inactive Ash Basin Groundwater Sub‐Scoring DocumentStation/Plant Name: Rogers Energy Complex ‐ Cliffside Steam StationEvaluation Criteria: Criteria 1 ScoreCriteria 2 Score
Environmental Groundwater Sub‐Scoring WorksheetClosure Options Evaluation Duke Energy(Option 1) (Option 2)Justification NotesClosure‐In‐Place Closure‐By‐Removal: Existing On‐Site Landfill 10 10Based on the predictive model for the year 2050, found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, simulated boron concentrations for the closure‐in‐place scenario did not show boron of 4,000 ppb or greater intersecting a surface water body.Based on the predictive model for the year 2050, found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, simulated boron concentrations for the closure‐by‐removal scenario did not show boron of 4,000 ppb or greater intersecting a surface water body.10 10Based on the predictive model for the year 2050, found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, simulated boron concentrations for the closure‐in‐place scenario did not show boron of 4,000 ppb or greater outside of the potential compliance boundary.Based on the predictive model for the year 2050, found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, simulated boron concentrations for the closure‐by‐removal scenario did not show boron of 4,000 ppb or greater outside of the potential compliance boundary.10 10Based on the predictive model for the year 2050, found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, simulated boron concentrations for the closure‐in‐place scenario did not show boron of 4,000 ppb or greater outside of the current Duke Energy property boundary.Based on the predictive model for the year 2050, found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, simulated boron concentrations for the closure‐by‐removal scenario did not boron of 4,000 ppb or greater outside of the current Duke Energy property boundary.010Based on a review of boron concentrations found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, this scenario is not marginally better than Option 2 (closure‐by‐removal).Based on a review of boron concentrations found in the November 2018 Preliminary Updated Groundwater Flow and Transport Modeling Report for Cliffside Steam Station, this scenario is marginally better than Option 1 (closure‐in‐place).Notes:1. Based on avaliable data at the time of scoring, the modeled plume considered boron at a concentration of 4,000 ug/l or greater;  4,000 µg/L does not represent a remediation goal, however this concentration does represent the EPA Tap Water Regional Screening Level (RSL) in resident tapwater for boron.2. The current compliance boundary is the compliance boundary found in the figure "Ash Basin Waste and Compliance Boundaries" provided to NCDEQ on 3/8/18.Rogers Energy Complex ‐ Cliffside Steam Station Unit 5 Inactive Ash Basin Groundwater Sub‐Scoring Document JustificationCriteria 1.  Modeled Plume Intersecting Surface WaterCriteria 2.  Groundwater Impact Beyond the Current Compliance Boundary Criteria 3.  Modeled Off‐site Impact Criteria 4.  Relative rank based on visual interpretation of modeled boron plume