20160742 Ver 2_WRC Comments_20191212

Strickland, Bev
From: Goudreau, Chris J.
Sent: Thursday, December 12, 2019 11:24 AM
To: Dunn, Lynne; 'Alan Stuart'
Cc: Besler, Doug A.; Leslie, Andrea J; Homewood, Sue; Annino, Amy M
Subject: RE: [External] Cedar Cliff Lake and East Fork Flow Releases
Attachments: 2019-05-17 cedar cliff auxillary spillway environmental report - revised - excerpts.pdf
Lynne and Alan,
If you remember, during an earlier drawdown event there was a significant and long-term turbidity problem in East Fork
Tuck. I can't remember if it was Bear or Cedar Cliff. Regardless, we all need make sure that kind of thing is avoided this
time. It caused quite an uproar with the public.
Maybe this current situation is different from the previous situation in terms of lake levels and how water is to be
released (surface or penstock). Our concerns are not just over turbidity from the construction, but any turbid water
released from the dam or powerhouse into the East Fork Tuck. The latter might be due to direct rain or high-water
events that cause erosion and turbidity from the exposed soils and substrate in the lake itself.
I looked over the 401 Certification (Appendix C), the Drawdown Plan (Appendix E), and the Water Quality Monitoring
Plan (Appendix F) in the spillway upgrade plan filed with FERC on May 17, 2019 (excerpts attached). Figure 1 of
Appendix F shows that there will be water quality monitoring sites below the dam and powerhouse. However, I couldn't
find any specifics on what the notification procedures and action plan will be in case of high turbidity (e.g., will the
spillway gates be closed?). The monitoring plan also indicates that monitoring equipment was to be installed in 2018 in
order to gather baseline data. Has that occurred? If so, what do those data reveal?
I see that Kevin Barnett is on the email below, but he is no longer with DEQ. So, I'm copying Sue Homewood and Amy
Annino to make sure DEQ is in the loop.
Chris
Chris Goudreau
Hydropower & Special Projects Coordinator
Habitat Conservation Division
NC Wildlife Resources Commission
645 Fish Hatchery Road
Marion, NC 28752
office: 828-803-6045
mobile: [phone]
chris.goudreau(cDncwiIdlife. org
ncwildlife.org
� V I f U38"'I
From: Dunn, Lynne <[e-mail]>
Sent: Thursday, December 12, 2019 8:30 AM
To: Adam and Mary Gelbaugh <[e-mail]>; Bob Wiggins <[e-mail]>;

Bryan Tompkins <[e-mail]>; Goudreau, Chris J. <[e-mail]>; David Leach
<[e-mail]>; Doug Odell <[e-mail]>; Tarver, Fred <[e-mail]>; DeWeese Jr.,
Jerry Lee <[e-mail]>; Kay Tufts <[e-mail]>; Ken Kastorff <[e-mail]>;
Kevin Barnett <[e-mail]>; Kevin Colburn <[e-mail]>; Mark Singleton
<[e-mail]>; Mike Wilkins <[e-mail]>; Richard Tyre <[e-mail]>; Rod Loman
<[e-mail]>; Sam Fowlkes <[e-mail]>; Tee Davis <[e-mail]>
Subject: [External] Cedar Cliff Lake and East Fork Flow Releases
External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to
[e-mail]
Good morning.
You all are aware of the construction taking place on Cedar Cliff Lake and dam. I just wanted to provide an update on
conditions and the changes that will begin on January 2nd. This phase requires the hydro station to be out of service for
upgrades and lake management will be through the spillway gate. The flows through the spillway gate can be
dangerously high during significant rainfall.
Because the station will be out of service and the gate releases will fluctuate, there will not be any releases showing on
the website. We do not want to post a flow release as they may be less than the hydro unit release and could be
misleading to the public. Please be aware of fluctuating river flows during this 4 month period. Please share this
information with others having an interest in the Tuckasegee River.
The following message has been updated on the web:
To support planned maintenance activities at the Cedar Cliff Dam, the Cedar Cliff hydro station will be out of service
from January 2nd through May 1st. A spillway gate will be open during this time and releases through the spillway gate
will fluctuate as inflows increase and decrease. Dangerous high flow conditions can exist downstream of Cedar Cliff
hydro station. Flows will be significantly higher during rainfall events. Cedar Cliff Lake will continue to be maintained at
lower levels during this work. The boat ramp at the Cedar Cliff Access Area will be unavailable during the drawdown and
the access area will be closed. The site will remain closed until construction is complete and the lake returns to a level of
93 feet or greater. Updated lake levels are available any time at duke-energy.com/lakes, by calling 800.829.5253, or on
the Duke Energy Lake View mobile app.
Please let me know if you have any questions.
Lynne Dunn
Email correspondence to and from this sender is subject to the N.C. Public Records Law and may be disclosed to third parties.

4
Environmental Report
Cedar Cliff Auxiliary Spillway Upgrade
East Fork Hydroelectric Project
FERC No. 2698
Prepared for Duke Energy Carolinas, LLC
Prepared by HDR
September 2018
Revised May 2019
�' DUKE `�

1 Introduction
The East Fork Hydroelectric Project (Project) is owned and operated by Duke Energy Carolinas, LLC
(Duke Energy) under a new license issued by the Federal Energy Regulatory Commission (FERC)
on May 4, 2011. The Project consists of three hydroelectric developments located on the East Fork
of the Tuckasegee River with a total installed capacity of 24.280 megawatts. From upstream to
downstream, the three developments are the Tennessee Creek Development (includes the Wolf
Creek Dam and the Tanasee Creek Dam), the Bear Creek Development, and the Cedar Cliff
Development (Appendix A, Figure 1).
The Cedar Cliff Dam (NATDAM NC00334), which is part of the Cedar Cliff Development, is located
on the East Fork of the Tuckasegee River near river mile (RM) 52.1 in Jackson County, North
Carolina. Via letter dated April 24, 2014, the FERC Atlanta Regional Office (ARO) required that Duke
Energy satisfy safe passage of the Inflow Design Flood (IDF), which is defined as the Probable
Maximum Flood (PMF), without overtopping Cedar Cliff Dam. The proposed remedial alternative to
safely pass the PMF involves modifications to the existing auxiliary spillway channel, installation of a
Fusegate system within the auxiliary spillway control section, placement of an approximately 8.5-foot
(ft)-high concrete parapet wall along the crest of the dam, and other appurtenant components.
Related activities will include new access road construction and modifications to an existing private
access road, construction of a new principal spillway bridge, and construction of an approximately
0.5-acre laydown area at the upstream approach channel to the auxiliary spillway, as well as
replacement of the existing spillway gate hoist with improved components that provide redundant
wire ropes, drive trains, and motors. The FERC Project boundary will be enlarged by approximately
three acres of Duke Energy -owned land to accommodate modifications to the Project works and
enlargement of the auxiliary spillway channel (Appendix A, Figure 2).
In addition to FERC approval, regulatory authorizations that will be required to carry out the
proposed modifications to the Project include an Individual Permit from the U.S. Army Corps of
Engineers (USACE) and North Carolina Department of Environmental Quality Division of Water
Resources (NCDWR) pursuant to Section 404/401 of the Clean Water Act (CWA) (see Section 4 of
this report). As such, Duke Energy has conducted extensive consultation with resource agencies
regarding the proposed construction activities, and the issued authorizations include measures for
resource protection and mitigation of unavoidable impacts.
Duke Energy has prepared this Environmental Report to facilitate the FERC staff's review of
environmental effects associated with Duke Energy's plans for the auxiliary spillway modifications
and compliance with requirements of the existing FERC license for the Cedar Cliff Development
throughout the construction period.
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2 Project Description
2.1 Existing Project Structures
The Cedar Cliff Development is located on the East Fork of the Tuckasegee River in Jackson
County, North Carolina, approximately six miles southeast of the Town of Cullowhee. Project works
are listed in ordering paragraph (13)(2) of the license, as amended by the Order Amending License
and Revising Installed Capacity issued February 21, 2012. A brief description of the Cedar Cliff
Development is included in this section. Cedar Cliff Dam is classified as high hazard due to the
potential loss of life and significant downstream property damage that would result from a dam
breach.
Constructed between 1950 and 1952, the Cedar Cliff Development (Figure 2-1) consists of a 590-ft-
long, 173-ft-high, earthen impervious core and rockfill embankment with nominal upstream and
downstream slopes of 1.3 horizontal (H):1 vertical (V), and a crest elevation of 2,343.5 ft AMSL'. The
dam impounds Cedar Cliff Lake, which has a surface area of 121 acres and total reservoir volume of
6,200 acre-feet at normal maximum pool and a full pond elevation of 2,330 ft AMSL. The nominal top
of dam elevation is approximately 2,340 ft AMSL and is 25 ft wide. The dam is topped by a concrete
parapet wall along its entire length with variable height from 1.5 ft to 3.7 ft which establishes the
constant crest elevation at 2,343.5 ft AMSL.
The Cedar Cliff spillways include the principal spillway on the right abutment and the auxiliary
spillway located at the left abutment (looking downstream) (see Figure 2-1). The principal spillway
includes a float -controlled 25-ft by 25-ft Tainter gate with a sill elevation of 2,305 ft AMSL. The
auxiliary spillway contains two erodible fuse plugs separated by a concrete splitter wall with a total
fuse plug length of 200 ft. The fuse plugs are constructed of crushed stone and sand with a sloping
core of compacted impervious fill. The left fuse plug is 112 ft long with a crest elevation ranging from
2,333 to 2,334 ft AMSL, and the right fuse plug is 88 ft long with a crest elevation ranging from 2,331
to 2,333 ft AMSL. Both spillways include rock cut channels that convey water to the 0.46-mile-long
Bypassed Reach of the East Fork of the Tuckasegee River located near the downstream toe of the
dam. The auxiliary spillway channel is formed by the rock -cut left abutment of the dam on the right
(looking downstream) and steep variable rock -cut walls ranging from 50 ft to 165 ft high on the left.
Water is conveyed to the Cedar Cliff powerhouses via a tunnel intake opening near the right
upstream toe of the dam. The water conveyance tunnel intake is protected by a 10.2-ft-wide by 16.4-
ft-high steel slide gate that is normally in the open position to facilitate hydroelectric generation.
Water is conveyed through a 1, 1 38-ft-long tunnel with a 12-ft-diameter concrete -lined section, a 13-ft
by 15-ft unlined section, and a 10-ft-diameter steel -lined section. The tunnel adjoins to an 8-ft-
diameter steel penstock at the main powerhouse, which contains one vertical Francis -type turbine
with a nameplate -rated capacity of 8,187 horsepower at best gate efficiency position, 168.5 ft of net
' All elevations presented in this report are based on the National Geodetic Vertical Datum (NGVD) 29
and are expressed as feet above mean sea level (ft AMSL).
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head and a discharge capacity of 555 cubic feet per second (cfs), connected to a generator rated at
6,375 kW at 0.85 power factor. The water conveyance system is the only low-level outlet for the
reservoir.
Construction of a new minimum flow powerhouse adjacent to the existing powerhouse was
completed in January 2013. The new powerhouse contains a generating unit consisting of a
turbine, generator, governor and associated high-pressure hydraulic system, control panel
boards, generator protection relays, and metal -clad switchgear. The continuous minimum flow
turbine has a nameplate -rated capacity of 526 horsepower based on 35 cfs and 154.5-ft net
head and is connected to a generator rated at 405 kW at 0.9 power factor. Water inflow to the
continuous minimum flow unit is conveyed from the 8-ft diameter steel penstock serving the
main powerhouse generating unit.
Vehicular and equipment access to the right abutment of the dam is via the Upper Access
Road, which traverses the crest of the dam. Access to the base of the auxiliary spillway
channel is by an existing lower access road, and the Shook Cove Access Road provides
access to the left abutment area (Appendix A, Figure 2).
14
Dam
t K'
I.
r.
Figure 2-1. Cedar Cliff Development
2.2 Existing Project Operation
The developments of the Project are operated in accordance with seasonal water availability and
licensed/normal operating ranges for lake levels. The Cedar Cliff Development maintains continuous
minimum flow release to the East Fork of the Tuckasegee River, and generation is scheduled in
coordination with the other developments of the East Fork Project, as well as the West Fork Project
(FERC Project No. 2686), to provide seasonal recreation flows in the vicinity of the Dillsboro section
of the (main stem) Tuckasegee River. During periods of high Development/Project inflow, the
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individual powerhouses are operated at maximum load to regulate reservoir levels within prescribed
normal limits. When Development/Project inflow exceeds the discharge capacity of the respective
powerhouses, then spillway gate operations will commence to regulate reservoir levels at or below
the respective normal maximum reservoir levels. In general, during periods of normal inflow, the
powerhouses will generate for a prescribed number of hours per day to support electric customer
needs and the downstream flow needs in the main stem of the Tuckasegee River, typically during
different periods each day. Continuous minimum flows are provided in the Wolf Creek Bypassed
Reach and at the Cedar Cliff powerhouse. Tainter gate releases are made, if necessary, to maintain
lake levels below prescribed maximum levels. During low inflow periods upon implementation of the
Low Inflow Protocol (LIP), generation is reduced on a weekly basis, along with corresponding weekly
reductions in bypass flows, Tainter gate releases for recreation (as applicable) and minimum
reservoir levels. The LIP is included in Appendix A of the FERC License for the East Fork Project.
The Cedar Cliff Development is operated to maintain a fairly constant target reservoir elevation of
2,328 ft AMSL throughout the year and to provide the required minimum flow from the Cedar Cliff
powerhouse, which, in turn, provides continuous flow in the two miles of stream between the Cedar
Cliff powerhouse and the confluence with the West Fork of the Tuckasegee River. The Cedar Cliff
Development is also operated to release water for recreational purposes during the recreation
season.
During normal Project operation, water is released from the upstream Bear Creek powerhouse,
located on the East Fork of the Tuckasegee River near RM 54.5, to Cedar Cliff Lake. The normal
reservoir target elevations for the Bear Creek Development are designed to provide some storage
for the historically wet period that occurs in the spring. Normally the Bear Creek powerhouse is
operated to support system peak loads and to refill Cedar Cliff Lake for off-peak generation and
water releases.
At a normal reservoir elevation of 2,330 ft AMSL, the discharge capacity of the Cedar Cliff principal
spillway is approximately 9,900 cfs. The combined discharge capacity of the principal spillway and
auxiliary spillway at reservoir elevation 2,343.5 ft AMSL (top of parapet) is approximately 80,000 cfs.
2.3 Additional Licensed Project Facilities
The FERC Project boundary around the Cedar Cliff Development encompasses two formal public
recreation sites, the Cedar Cliff Access Area, and the Shook Cove Access Area. The 1.86-acre
Cedar Cliff Access Area is located on Cedar Cliff Lake, at 3387 Shook Cove Road, Tuckasegee, NC
28783 and includes a boat ramp, pier, portable toilet, and parking. The operations and maintenance
of this site are provided by the North Carolina Wildlife Resources Commission (NCWRC) through an
agreement with Duke Energy. The 8.35-acre Shook Cove Access Area, which is leased by Duke
Energy to Jackson County and maintained by Jackson County, is located downstream of the Cedar
Cliff powerhouses. This site includes accessible parking, a boat ramp, canoe/kayak laydown area,
and trash receptacles, as well as a downstream boat take-out area. The locations of the recreation
sites are shown on Exhibit G-2, which is included as Figure 3 in Appendix A, for reference.
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3 Purpose and Description of Proposed Work
3.1 Purpose of Proposed Work
The purpose of the proposed upgrade project is to modify the existing Cedar Cliff Dam auxiliary
spillway as a remedial alternative to safely pass the IDF. As noted above, the Cedar Cliff
Development has an existing discharge capacity of approximately 80,000 cfs at reservoir elevation
2,343.5 ft AMSL. This discharge capacity represents combined discharge from the main generating
unit, principal spillway (Tainter gate), and auxiliary spillway (fuse plugs). The PMF peak outflow,
which was approved by the FERC on June 22, 1994, is approximately 192,000 cfs. Based on
engineering evaluations, the spillway discharge capacity would need to be increased by at least
112,000 cfs to prevent overtopping of Cedar Cliff Dam. In correspondence to Duke Energy dated
April 24, 2014, the FERC identified the OF as the PMF, citing downstream potential hazards, and
requested a plan and schedule that addresses the ability of Cedar Cliff Dam to safely pass all flows
up to and including the IDF. Due to the existing Cedar Cliff site terrain, limited viable options are
available to increase spillway discharge capacity to this magnitude.
The elements and design of the proposed auxiliary spillway upgrade reflect evaluation of numerous
alternative scenarios developed by a Core Team of FERC, Duke Energy, and HDR representatives
from 2014 through 2017. Based on discussions from the August 2015 meeting, the Core Team's
preferred alternative scenario involves modifications to the existing auxiliary spillway channel. This
option was selected as the most viable alternative in safely discharging the Cedar Cliff OF without
overtopping based on technical merits, including developing a practical engineered solution,
constructability, and maintenance. By letter to Duke Energy dated May 17, 2016, the FERC ARO
provided concurrence with Duke Energy's plans.
The following list summarizes major milestones for the auxiliary spillway upgrade project:
• FERC issued acceptance of Fusegate Alternative for Spillway Remediation in May 2016.
• 404/401 Permit applications submitted and approved in March 2017 and December 2016,
respectively. Request for amended 404/401 Permit submitted to USACE and NCDWR on
May 16, 2019.
• Subsurface Drilling Program initiated in August 2016.
• Engineering Design -Potential Failure Mode Analysis (PFMA) meeting conducted with FERC
in January 2017.
• Shook Cove Access Road completed in June 2017.
• Alden Research Laboratory, Inc. (Alden) completed Phase 1 Physical Scale Model (1:8 and
1:19 scale) testing in June 2017.
• Geological and Geotechnical Subsurface Investigation Report submitted to the FERC in June
2017.
• 30 Percent Design Package Submitted to Duke Energy in November 2017.
• Rock Spoil Evaluation Report completed in January 2017.
• FERC acceptance of PFMA, preliminary hydraulic design, and subsurface investigation
reports in January 2018.
• Alden completed Phase 2 and Phase 3 1:19 scale model testing in March 2018.
• Fifth Core Team meeting conducted in August 2018.
• Final hydraulic design report submitted to the FERC in February 2019.
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• Submittal of engineering design package to the FERC completed March 18, 2019.
• FERC review and acceptance of engineering design package anticipated during third quarter
2019.
• Initiation of long-term reservoir drawdown and redundant spillway gate hoist replacement
scheduled to begin in September 2019.
• Auxiliary spillway upgrade construction project scheduled to commence during fourth quarter
of 2019.
3.2 Description of Proposed Work
The proposed work includes modifications to the existing auxiliary spillway channel, replacement of
the existing parapet wall with an approximately 8.5-ft-high new PMF wall along the crest of the dam,
and installation of a Fusegate system within the auxiliary spillway control section (Appendix A,
Figure 2).
Cedar Cliff Lake will be drawn down approximately 30 ft to facilitate construction activities for the
proposed work, including spillway gate hoist replacement, spillway gate maintenance, powerhouse
transformer replacement2, and auxiliary spillway modifications. The principal spillway Tainter gate
(sill elevation 2,305 ft AMSL) will be left in a partially open position to facilitate the passage of Cedar
Cliff Development inflow exceeding approximately 590 cfs (Le, the combined maximum hydraulic
capacity of the Cedar Cliff powerhouses).
The existing auxiliary spillway control section (two fuse plugs and a single concrete splitter wall) will
be removed. Approximately 600 ft of the auxiliary spillway channel length will be modified (variable
width and depth increased) through rock excavation (rock splitting and controlled rock blasting).
Sufficient rock excavation and foundation preparation will occur at the existing fuse plug control
section to lower the sill elevation from 2,315 ft AMSL to 2,305 ft AMSL. The existing auxiliary
spillway channel control section will be widened from 200 ft to 250 ft. The existing average auxiliary
spillway channel width will be increased from approximately 95 ft to 145 ft. The existing channel
bottom will be lowered 15 ft, on average. The rock -cut height of the left (looking downstream)
channel wall will be increased from an average of 127 ft (160 ft maximum) to an average of 162 ft
(220 ft maximum), based on the existing topography and proposed rock cut slope of 1:6 (H:V).
Intermediate benches (25-ft wide) are proposed along the left channel wall to divide the steep rock
cut slopes into 60-ft to 100-ft sections (Appendix A, Figure 4). The estimated bulk volume of all
material removed from the auxiliary spillway will be approximately 283,300 cubic yards (cy). In
addition, design consideration is being given to construct a concrete Training Wall along a portion of
the right face of the auxiliary spillway channel. The right side of the existing rock cut face of the
2 Powerhouse transformer replacement relates to the scope for this project and the associated reservoir
drawdown because this maintenance is required to ensure the reliable operation of the powerhouse as
the primary means to pass water through the Cedar Cliff Development throughout the auxiliary spillway
construction period. The Cedar Cliff Development presently has four single-phase step-up transformers,
each rated at 6.6 kV primary / 66 kV secondary and two of which are in service. All four transformers are
being replaced with 3-phase, dry type units, enclosed in a housing, with all work to be conducted within
the general area/footprint of the existing switchyard. The Cedar Cliff powerhouses will remain offline
throughout the transformer replacement process.
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auxiliary spillway channel is the left abutment of the dam and the Training Wall provides additional
protection to the abutment.
The new control section of the auxiliary spillway will be comprised of six Fusegates. Each cast -in -
place Fusegate will be approximately 41.5-ft wide by 25-ft high by 24.67-ft deep and will be located
on a reinforced concrete sill with reinforced concrete abutment wall on the left side and a training
wall on the right side of the spillway. The top of the Fusegate crest will be at normal pool elevation
(2,330 ft AMSL). A single toe block will be located in front of each gate to prevent the Fusegates
from sliding downstream and will serve as a tipping plane during Fusegate activations. The toe
blocks will be constructed of stainless steel. The six Fusegates will serve as a semi -Labyrinth weir
spillway and will not begin to activate until significant inflow events exceed reservoir levels that are
10.5 feet above normal pond elevation 2,330 ft, per engineering design. The first Fusegate will be
activated at reservoir elevation 2,340.5 ft AMSL (Cedar Cliff inflow approximately 79,100 cfs); the
sixth Fusegate will be activated at reservoir elevation 2,345.5 ft AMSL (178,500 cfs)3.The activation
of each Fusegate will be facilitated by the construction of an upstream Inlet Well Tower containing
six individual Fusegate inlet wells. Each Fusegate will be primed by rising reservoir levels within the
Inlet Well Tower based on designed activation water levels while using individual pipes installed in
an excavated trench connecting the individual inlet wells/pipes to their respective Fusegate. Each of
the six Fusegates will be designed for activation based on engineered levels of uplift pressure and
tipping moment correlating to prescribed reservoir water surface levels that adjoin the Inlet Well
Tower.
The existing parapet wall (top -of -wall elevation 2,343.5 ft AMSL) will be removed and replaced with a
PMF wall with a proposed top -of -wall elevation of 2,348.5 ft AMSL. The proposed PMF wall design is
based upon the peak reservoir PMF stage elevation of 2,345.5 ft AMSL with allowance for wave run-
up design criteria. The Cedar Cliff PMF wall will be keyed into the inclined core of the dam.
An approximately 0.5-acre laydown area for the spoil barge loading zone will be placed at the
upstream end of the rock excavated approach channel (elevation 2,304 ft AMSL) of the auxiliary
spillway. As decided in consultation with natural resource agencies as part of the application process
for the Individual Permit from the USACE and NCDWR pursuant to Section 404/401 of the CWA, all
excavated materials from the auxiliary spillway excavation will be loaded onto a barge and deposited
in Cedar Cliff Lake to eliminate potential impacts to identified adjoining USACE-jurisdictional waters
and intact terrestrial habitats at alternate spoil locations. This activity will result in an approximate
8.1-acre footprint within the reservoir. The location of the spoil area, shown on Figures 2 and 5a in
Appendix A, is upstream from the dam and plant intake, with the right edge located toward the
original thalweg of the East Fork of the Tuckasegee River channel. The top of the spoil elevation
(2,250 ft AMSL) is approximately 80 feet below full pond elevation. Plan and section views of the
spoil repository are shown on Figures 5a through 5c in Appendix A. The volume capacity of the spoil
repository (approximately 353,600 cy) is in excess of the estimated quantity of all excavated material
to be placed in the reservoir.
3 For perspective, the pre -Cedar Cliff construction flood of record on the East Fork of the Tuckasegee
River was approximately 28,000 cfs on August 30, 1940. The historical flood of record for Cedar Cliff
Dam is approximately 9,000 cfs, which occurred on October 4, 1964.
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To sustain normal generation operation of the Bear Creek powerhouse during the 30-ft drawdown of
Cedar Cliff Lake, a rock vane was constructed in the immediate tailrace area below the Bear Creek
powerhouse in October 2018. The nominal crest elevation of the overall 121-foot long rock vane will
be approximately 2328.5 ft AMSL. The nominal height of the rock vane design varies from 2.5 ft to 7
ft with a variable base width of 10 ft to 22 ft. Natural rock material deposited in the Bear Creek
spillway outfall area located approximately 350 ft upstream of the Bear Creek powerhouse was
gathered to construct the rock vane with variable rock diameters of 2 ft to 4 ft. The volume of rock
material required to facilitate rock vane construction is approximately 65 cy. The retention pool
created by the rock vane will provide sustained back pressure against the Bear Creek turbine in
order to sustain generation while minimizing runner cavitation during the extended Cedar Cliff Lake
drawdown period. The rock vane was constructed in October 2018, during the scheduled 10-ft
drawdown of Cedar Cliff Lake authorized by the Order Approving Temporary Variance of Elevation
Requirements Pursuant to Article 401 issued by FERC on April 24, 2018 and the Individual Section
404 permit issued by USACE (see Section 4 of this report).
Additional construction activities associated with the auxiliary spillway upgrade include the following:
• During the reservoir drawdown, construction of an access road (1951 Access Road)
connection below the full pond elevation 2,330 ft AMSL to connect to the end of the auxiliary
spillway approach channel and remaining 1951-1952 construction road. The new access
road connection will provide a safe corridor at a suitable grade for equipment to travel
between the Shook Cove Access Road and the approach channel to facilitate auxiliary
spillway modifications and Fusegate installations. The proposed 14-foot-wide 1951 Access
Road below the full pond elevation will extend approximately 548 feet, resulting in 0.22 acre
of open water permanent fill impacts. Construction of the 1951 Access Road will result in a
maximum of approximately 57,000 cy (subject to change and actual quantity likely to be less
than this amount) of excavated material to accommodate a peninsula hillside cut of 2H:1 V.
• Extending Shook Cove Access Road to Inlet Well Tower (considered as upper segment of
the 1951 Access Road).
• Construction of an additional barge access area at the existing Cedar Cliff Access Area,
including an approximately 550-foot-long temporary access road to the proposed barge
location. The barge access temporary construction road is necessary to maintain access to
Cedar Cliff Lake for equipment and material support for the Project during the reservoir
drawdown period. An approximately 500-foot long temporary stone construction access road
is proposed below Cedar Cliff Lake normal reservoir elevation of 2,330 ft, terminating at the
2,300 ft msl drawdown elevation for barge access.
• Improvements to existing Upper Access Road, including addition of an eight -inch layer of
compacted aggregate, and realignment of the Upper Access Road at the right abutment and
interface with the access road across Cedar Cliff Dam in association with the new spillway
bridge described below.
• Improvements to existing Lower Access Road, including grading, raising the road bed, and
widening to 12 feet.
• Construction of a new Cedar Cliff Principal Spillway Bridge (construction is underway in
2019). The new bridge will serve as an independent structure, located upstream of the
existing spillway bridge, with the PMF as the design criteria. The bridge will provide
construction access during the auxiliary spillway upgrade project. Following completion of
construction, the bridge will serve as the primary bridge for access to the top of dam,
principal spillway, and right abutment of the auxiliary spillway-Fusegate control section.
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• Spillway gate maintenance and hoist replacement with improved components that provide
redundant wire ropes, drive trains, and motors to occur at the start of the drawdown period in
September 2019.
3.3 Schedule of Proposed Work
Duke Energy anticipates the duration of construction activities at the Cedar Cliff Development for the
auxiliary spillway upgrade will be approximately 25 months, with construction activities expected to
span the period from September 3, 2019 through September 2021, with refill of the reservoir
expected to begin in October 2021.
4 Regulatory Permits and Associated
Consultation
In addition to FERC approval, major regulatory authorizations for the construction of the proposed
modifications to the Project include an Individual Permit from the USACE and NCDWR pursuant to
Section 404/401 of the CWA.
A pre -application meeting was held with Duke Energy and representatives from Jackson County, the
USACE, and the U.S. Fish and Wildlife Service (USFWS) on December 1, 2015 to discuss the
proposed auxiliary spillway upgrade project, associated environmental impacts, and to develop a
collaborative permitting strategy.
An Individual Permit application for the proposed auxiliary spillway upgrade was submitted on July
26, 2016 and supplemented on October 20, 2016 and November 15, 2016. On March 22, 2017, the
USACE issued an Individual Permit pursuant to Section 404 of the CWA for the placement of fill in
waters of the U.S. during the Cedar Cliff Development auxiliary spillway upgrade project. A copy of
the Section 404 permit is provided in Appendix B.
On December 9, 2016, the NCDWR issued an individual CWA Section 401 Water Quality
Certification (WQC) for the construction activities and associated impacts to streams and open
waters during the Cedar Cliff Development auxiliary spillway upgrade project. A copy of the Section
401 WQC is provided in Appendix C.
On May 16, 2019, Duke Energy requested an amendment to the previously approved Section 404
and Section 401 Individual Permit, to incorporate the revised water quality monitoring plan, an
update to the USACE Individual Special Condition 20.0 regarding required depth of Turbidity
Barriers, and request authorization for additional impacts to Cedar Cliff Lake to accommodate the
proposed Cedar Cliff Access Area — Temporary Construction Access Road (Appendix C). An
amended Section 404 and Section 401 Individual Permit is expected to be issued by USACE and
NCDWR, respectively, in the second quarter of 2019.
In addition to the aforementioned pre -application meeting, multiple site visits were conducted by the
USFWS with representatives from Duke Energy and HDR. On August 19, 2016, following Duke
Energy's Individual Permit application to the USACE and NCDWR, the USFWS submitted a report in
accordance with the provisions of the National Environmental Policy Act, Fish and Wildlife
Coordination Act, and Section 7 of the Endangered Species Act. The August 2016 report from
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USFWS included recommended provisions for minimizing potential impacts during construction to
the Northern Long -Eared Bat and Indiana Bat (see Section 5.6) as well as erosion control and
reservoir drawdown. A copy of this correspondence is provided in Appendix D.
Consultation with the North Carolina State Historic Preservation Office (NCSHPO) and Eastern Band
of Cherokee Indians (EBCI) Tribal Historic Preservation Office (THPO) regarding the proposed
construction is required by Section 106 of the National Historic Preservation Act for both the
Individual Permit application to the USACE and pursuant to the Historic Properties Management
Plan (HPMP) for the Project. As provided by the HPMP, in the event of a large, planned, extended
drawdown, the Licensee will consult with the NCSHPO and the EBCI THPO regarding the need to
conduct archaeological surveys of the exposed area. A large, planned, extended drawdown is any
planned drawdown where the pond elevation will remain at least 10 ft below the normal minimum
elevation for a minimum of 30 consecutive days.
Pursuant to the requirements of the HPMP, Duke Energy sent a letter dated August 5, 2016 to the
NCSHPO and EBCI THPO providing notification and description of the planned construction
activities and associated drawdown at the Cedar Cliff Development. No response was received by
Duke Energy from the EBCI THPO. Via letter dated August 30, 2016, the NCSHPO indicated it is
unlikely that any archaeological resources that may be eligible for inclusion in the National Register
of Historic Places (NRHP) would be adversely affected by the planned construction activities and
drawdown. The NCSHPO requested that Duke Energy take photographs to document the current
condition of the dam and its surroundings pursuant to their guidelines. A copy of the August 2016
letter from NCSHPO is provided in Appendix E, Attachment 2. Duke Energy is in the process of
completing the photographic documentation of the Cedar Cliff Dam and its surroundings pursuant to
the NCSHPO's request and guidelines.
On August 7, 2018, HDR, on behalf of Duke Energy, sent a copy of the draft Environmental Report
to the USFWS, NCDWR, and NCWRC for their review and comment within 30 days of receipt. The
USFWS, NCDWR, and NCWRC all responded within 30 days of receipt of the draft report with no
further comments or recommendations. See Appendix G for agency replies and the draft
Environmental Report.
On October 1, 2018, Duke Energy filed the final Environmental Report with FERC, in support of
Duke Energy's request for approval for temporary variance from License Article 401. FERC issued
public notice of Duke Energy's application on November 5, 2018. No comments, motions to
intervene, or protests were in turn filed. Duke Energy updated this Environmental Report in the
spring of 2019 to reflect the final proposed duration for the reservoir drawdown (25 months) in
support of construction and distributed the updated version to USFWS, NCDWR, and NCWRC for
their review and comment within 30 days of receipt. Following agency review, Duke Energy plans to
file the updated Environmental Report and request for approval for temporary variance from License
Article 401 with FERC.
As required by the North Carolina Sedimentation Pollution Control Act and local ordinances, Duke
Energy will also be filing a Land Disturbance permit application with Jackson County and an Erosion
and Sediment Control (ESC) Plan with the North Carolina Department of Environmental Quality for
approval in advance of construction.
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5 Environmental Resources
To facilitate the FERC's Division of Hydropower Administration and Compliance review of
environmental effects of Duke Energy's plans for the Cedar Cliff auxiliary spillway upgrade in
conjunction with review of the final design and construction plans by the FERC's Division of Dam
Safety and Inspections- ARO, resources that may potentially be impacted by the planned
construction activities and proposed protection, mitigation, or enhancement measures are identified
and described below. The information presented in this section was obtained from evaluations
conducted for the relicensing of the Project, as well as desktop evaluations and on -site surveys
performed by qualified resource specialists and agency consultation conducted in support of the joint
USACE/NCDWR permitting process for the auxiliary spillway upgrade.
The FERC issued a new license for the East Fork Hydroelectric Project on May 4, 2011, which
incorporates the conditions of the Section 401 WQC issued by the North Carolina Department of
Environment and Natural Resources, Division of Water Quality (now NCDWR) on July 30, 2010 and
the condition submitted by the USFS pursuant to Section 4(e) of the Federal Power Act4. Potential
effects of the planned construction on license requirements, and the need for temporary variances
from license requirements, are addressed in Section 6 of this document.
5.1 Geological and Soil Resources
5.1.1 Affected Environment
The Project is situated in the Blue Ridge physiographic province, a deeply dissected mountainous
zone that extends northeast -southwest from southern Pennsylvania to central Alabama. The
physiography of Jackson County consists of high, intermediate, and low mountains; floodplains; and
low stream terraces. The East Fork Tuckasegee River is located in the Tuckasegee River
watershed, which generally drains to the north. The Project is surrounded by open water, rural
residential, pastureland, and forested undeveloped lands.
The surficial geology in the region includes late Precambrian to early Paleozoic metasedimentary,
metavolcanic, and igneous rocks from the Tallulah Falls Formation (TFFm) and the Whiteside
Mountain Pluton. Rock types consist of biotite gneiss, garnet-aluminous schist, muscovite-biotite
gneiss, and igneous rocks ranging from quartz diorite to granodiorite. Surficial deposits include
alluvial deposits along the major streams, low and high-level stream terrace deposits, and colluvial
deposits along the mountain slopes. The soils in the area vary from shallow to very deep and are
well -drained to excessively -drained owing to the landscape, which is characterized by rugged,
dissected intermediate mountains, prominent mountain peaks and rock cliffs and moderately broad
ridgetops, wide side slopes, and narrow coves (FERC 2006).
The Cedar Cliff Development is located in the Eastern Tennessee -Western North Carolina seismic
zone, corresponding to the USGS Seismic Zone 2, which is considered a zone of potentially
4Duke Energy Carolinas, LLC, 138 FERC ¶ 62,146
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moderate damage. There are no known active faults in the vicinity of the East Fork Project (FERC,
2006).
5.1.2 Potential Environmental Effects
General construction activities, including modifications to access roads and development of laydown
areas, will disturb geological and soil resources. Such activities will have short-term impacts to
geological and soil resources in the immediate work area.
Planned construction activities include deepening and widening the existing auxiliary spillway
channel and replacing the two existing fuse plugs with a Fusegate system. Approximately 75 percent
of the auxiliary spillway channel length will be modified (variable width and depth increase) through
residual soil and rock excavation (i.e., rock splitting and controlled rock blasting). Additional rock
excavation and foundation preparation will occur at the existing fuse plug control section. In support
of engineering design for the auxiliary spillway upgrade, a geotechnical subsurface investigation was
conducted by HDR for Duke Energy in August -December 2016. The data obtained from the 2016
subsurface investigation was used to develop the foundation design for the planned Fusegate
structure, the design of the rock cuts for the auxiliary spillway channel improvements, as well as to
investigate and determine the potential effort required to excavate the existing rock to widen and
deepen the existing auxiliary spillway channel.
Additional recommendations from the geotechnical investigation have been incorporated into the
design and plans for the auxiliary spillway upgrade, including analysis of scour in the spillway
channel, evaluation of potential acid -production from Iithologies within the TFFm (see Section 5.2.2),
and establishment of design requirements for temporary and permanent rockfall stabilization and
protection measures during construction and for long-term performance of the Fusegate and
auxiliary spillway.
5.1.3 Proposed Mitigation Measures
For the protection of geological and soil resources, as well as water and biological resources during
construction activities and the reservoir drawdown, ESC measures will be implemented and
maintained, as necessary per the requirements of the WQC issued by the NCDWR on December 9,
2016 and to maintain compliance with the state water quality standards, statutes, or rules. As
required by Condition 6 of the WQC, to prevent erosion and sedimentation, Duke Energy will
develop and secure approval of an ESC Plan prior to commencing drawdown of the water level in
the reservoir. (Additionally, prior to construction, a Soil Erosion and Sediment Control Plan will be
submitted to FERC ARO along with other final construction plans and specifications for FERC
approval.) The work area will be inspected daily for signs of erosion or degradation and ESC device
failure. Following construction, all disturbed areas will be restored and re -graded to pre -construction
grades and re -vegetated with native vegetation.
As noted above, results of and recommendations from the geotechnical subsurface investigation
have been incorporated into the final design and plans for the auxiliary spillway upgrade. The
Geological and Geotechnical Subsurface Investigation Report for the Cedar Cliff auxiliary spillway
upgrade was filed by Duke Energy with the FERC ARO on July 14, 2017 and accepted by FERC via
letter to Duke Energy dated January 4, 2018.
In accordance with the Hydro Project Maintenance & Emergency Protocol (HPMEP) for the Project
(Appendix A of the license order), and as required by Condition No. 3 of the WQC issued by
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NCDWR on December 9, 2016, Duke Energy has prepared a Cedar Cliff Lake Drawdown Plan for
the 25-month drawdown planned for 2019-2021 (Appendix E). The Drawdown Plan describe the
procedures and schedule associated with the Cedar Cliff Lake drawdown and measures to maintain
compliance with the state water quality certification, FERC license and associated plans, and the
Tuckasegee Cooperative Stakeholder Team Settlement Agreement, as applicable. The Drawdown
Plan includes measures for the protection of geological and soil, as well as water, biological, cultural,
and recreation resources.
5.2 Water Quality and Quantity
5.2.1 Affected Environment
The Cedar Cliff Development is part of the Tennessee River system and lies within the Tuckasegee
River watershed (HUC 06010203), which is a subbasin of the Little Tennessee River. The total
drainage area of the Tennessee River is 42,000 square miles, of which the Little Tennessee River
basin contributes 2,627 square miles, including more than 655 square miles from the Tuckasegee
River watershed. The Tuckasegee River flows through the cities of Cullowhee, Sylva, and Bryson
City, North Carolina before it joins the Little Tennessee River almost 50 miles from its headwaters.
The Project reservoirs are surrounded by steep, forested slopes ranging in elevation from 2,250 to
3,800 ft AMSL.
The Tuckasegee River watershed contains some of the most pristine, high -quality waters in the state
of North Carolina and supports numerous trout streams. The East Fork of the Tuckasegee River
(including Cedar Cliff Lake) from Tennessee Creek to the West Fork Tuckasegee River is classified
as a Water Supply III (WS-III), Primary Recreation Class B; Trout Waters surface water, as
designated by the NCDWR.
At full pond elevation 2,330 ft AMSL, Cedar Cliff Lake has a surface area of 121 acres and a total
reservoir volume of 6,200 acre-feet. The reservoir inundates about 2.6 miles of the East Fork
Tuckasegee River and has a total drainage area of 80.7 square miles, including the direct tributaries
to the lake. Average annual inflow to Cedar Cliff Lake is approximately 284 cfs, which is seasonally
variable but regulated by releases from the upstream Bear Creek Development. The reservoir has a
maximum depth of 150 feet, a mean depth of 55 feet, and a mean water retention time of 15.3 days
at full pond elevation. According to the NCDWR, water quality in Cedar Cliff Lake has been
monitored since 1988 and the lake has been characterized as oligotrophic (i.e., very low biological
productivity) since at least that time. Based on water quality sampling conducted by the NCDWR
(data provided to Duke Energy) in Cedar Cliff Lake between 1988 and 2014, water temperature in
the late summer (August to September) months ranged from approximately 10 degrees Celsius (°C)
at lower elevations to approximately 27°C at a depth of 0.5-ft beneath the surface. The maximum
surface -to -bottom (approximately 100 ft) temperature differential was 19.8°C, and the minimum
surface -to -bottom temperature differential was 4°C.
Additional characteristics of Cedar Cliff Lake, under existing and temporary construction conditions,
are listed in Table 5-1.
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Table 5-1. Cedar Cliff Lake Characteristics
Parameter 001�
Full Pond (Spillway Elevation) 2,330 ft AMSL
Tainter Gate Sill Elevation 2,305 ft AMSL
30-ft Drawdown Elevation 2,300 ft AMSL
Cedar Cliff Hydro Intake Elevation 2,202 ft AMSL
Proposed Elevation of Top of Spoil 2,250 ft AMSL
Lake Volume below Full Pond A 6,320 acre-ft
Lake Volume below Tainter Gate -�■ 3,742 acre-ft
Lake Volume below 30-ft Drawdown Epp 3,386 acre-ft
Lake Volume below Hydro Intake 42 acre-ft
Mean Outflow' qq
209.0 cfs
Mean Retention Time (Full Pond)
15.3 days
Mean Retention Time (30-ft Drawdown)
8.1 days
Max Depth at Dam (Full Pond)
148 ft
Max Depth mid -lake sampling (Full Pond)
106 ft
pH Range
5.7-8.0
Mean Alkalinity2
0.13 meq/1
Conductivity Range2 _j 14-20 S/m
Mean Oxygen below 2,250 ft-AMSL2�IN 7.8 mg/I
Minimum Observed Oxygen2 ON
4.2 mg/I
Mean Nitrate2 qN, 0.019 mg/I
Calculated from Cedar Cliff operations (1953-2013)
2 from NCDENR data reported in NP&L (2000)
mg/l=milligrams per liter; meq/l=mill iequivalents of solute per liter; S/m=Siemens per meter
As noted in Section 2, Cedar Cliff Dam creates a 0.46-mile-long Bypassed Reach from the base of
the dam to the Cedar Cliff powerhouse discharge and back to the East Fork Tuckasegee River. No
continuous minimum flow from the reservoir is provided to the Bypassed Reach.
5.2.2 Potential Environmental Effects
Throughout the construction period, Duke Energy will continue to release minimum flows from Cedar
Cliff Lake to the downstream East Fork Tuckasegee River as required by license Article 404 and
Condition 6 of the 2010 WQC. Potential water quality impacts due to construction of the planned
auxiliary spillway upgrade and associated facilities may result from drawdown of the reservoir,
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physical construction activities that have the potential to cause erosion or sedimentation, and
placement of excavated materials in Cedar Cliff Lake.
As noted above in Section 3.2 and described in detail in the Drawdown Plan included in Appendix E,
Cedar Cliff Lake will be drawn down 30 ft for approximately 25 months to allow for construction of
the auxiliary spillway upgrade. The drawdown would result in a temporary reduction in water quantity
in Cedar Cliff Lake. Additionally, sediment in the drawdown zone has the potential to be subject to
erosion and resuspension. The drawdown and other planned construction activities, including rock
cutting and placement of excavated material in the reservoir, have the potential to result in
temporary and localized increases in turbidity in Cedar Cliff Lake.
Potential water quality impacts associated with the placement of the excavated materials in the
reservoir have been evaluated throughout the engineering design and Section 404/401 permitting
process. Through analysis of the results of geotechnical and geological subsurface investigations
performed at the Cedar Cliff Development in late 2016, pyrite (FeS2) was identified in rock
exposures at the site and in the rock core from boreholes drilled for the subsurface investigation.5
Rocks with greater than 1 percent pyrite and/or pyrrhotite by volume or pyritic sulfur in excess of 0.5
weight percent are considered to be potentially acid -producing (Byerly 1990 and Byerly 1996, in
HDR 2018a). Pyrite can react in the presence of atmospheric oxygen and water to form ferrous
sulfate and sulfuric acid. Although some acid -drainage is produced by natural weathering (Huckabee
et al. 1975), construction activities can expose large volumes of rock containing sulfide minerals to
oxidizing conditions. Subsequent leaching of the oxidation products by rainfall/groundwater result in
the formation of acid -drainage characterized by low pH values, high concentrations of sulfate, and
mobilization of metals such as iron, aluminum, and manganese. A rock spoil evaluation was
conducted for Duke Energy to further characterize the pyritic rocks at the site, specifically with
regard to pyrite crystal size and mineral abundance, and to evaluate the potential impact of the
placement of pyritic rock spoil into Cedar Cliff Lake (HDR 2018b).
Subsequent petrographic analyses of metasedimentary rocks of the TFFm from the rock cores
indicated that the garnet mica schist, mica schist, and schistose biotite gneiss lithologies contained 2
percent to 7 percent pyrite by volume (HDR 2017). Based on boreholes drilled during the geological/
geotechnical site investigation for the auxiliary spillway upgrade, approximately 26 percent of the
total excavated material (73,600 cy) will be made up of these three rock lithologies (HDR 2017).
There are no known instances of acid -drainage related to the metasedimentary rocks of the TFFm in
the region surrounding the site. The results of the rock spoil evaluation demonstrated a low potential
for acid -production due to the coarse -grained pyrite -bearing rocks in the TFFm, based on the
petrographic analysis of samples that have been continuously submerged since the reservoir was
filled; this is consistent with the site's 65-year history of non -acid -production.
As described in the Water Quality Monitoring Plan (Appendix F), the physical and chemical
properties of Cedar Cliff Lake (Table 5-1) also influence the amount of oxidation production in the
5 Note that the acid -producing potential of certain metasedimentary rocks of the Blue Ridge Province has
been known since the late 1960s. The Cedar Cliff site is underlain by rocks of the TFFm; the major acid -
producing rocks are graphitic schists of the Anakeesta Formation, located west of the Project. There are
no known instances of acid -drainage related to the TFFm that underlie the Project.
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reservoir and downstream reaches. For example, the wide range of pH values reflect the poor
buffering capacity of the low alkalinity water as biological activity metabolized carbon dioxide. In
addition, the low ionic strength, as measured by conductivity, also influences the ability to measure
accurate pH values as well, indicating the poor buffering capacity. The relatively high dissolved
oxygen concentrations in the lake would favor higher rates of pyrite oxidation, but these rates would
be significantly low compared to exposure to atmospheric oxygen. The low nitrate concentrations
would limit the amount of de -nitrification associated with anaerobic nitrate -dependent microbial pyrite
oxidation. Probably the most significant factor limiting the accumulation of pyrite oxidation products
in the lake is the very high flushing rate of the reservoir. The average retention time of the water at
full pool is 15.3 days; at a 30-ft drawdown the average retention time of the water is reduced to 8.1
days. Also, at the 30-ft drawdown, the primary means of maintaining the lake level is through
powerhouse operation, which draws water from the bottom of the lake, further reducing the
accumulation of oxidation products in the lake.
5.2.3 Proposed Mitigation Measures
As described above in Section 5.1.3, Duke Energy will develop and secure approval of an ESC Plan
prior to commencing drawdown of the water level in the reservoir. Best Management Practices
(BMPs) in the vicinity of construction activities will also be employed for the protection of water
quality, including but not limited to installing protective silt fencing, restricting the use of wet concrete
within surface waters, and implementing and maintaining a spill prevention plan for heavy
equipment. Following construction, all disturbed areas will be restored and re -graded to pre -
construction grades and re -vegetated with native vegetation.
As described in the Drawdown Plan included in Appendix E, during drawdown and immediately after
the drawdown elevation is reached, inspections will be performed by Duke Energy once per week
and after significant rainfall events (e.g., precipitation estimates for the Project area of 1 inch or
greater within 24 hours), as feasible. Approximately one month after the drawdown is reached and
based on the condition of the exposed lake bottom, inspections will occur at least monthly for the
duration of the drawdown. Inspections will identify mass wasting and sloughing on the banks and
remediation measures will be installed as needed. Remedial measures may include installation of
straw bales along the banks or similar measures to decrease velocity of waters, decrease erosion,
and minimize the amount of sediment released to Cedar Cliff Lake through erosion. Erosion control
materials (i.e., straw bales) will be available onsite in the event such materials need to be rapidly
deployed via barge. Additionally, Cedar Cliff Lake will be lowered and refilled at a rate no greater
than 3 ft per 24 hours.
Pre- and post -construction water quality (i.e., pH) monitoring has been requested by the agencies
(USACE, NCDWR, and NCWRC) to confirm the disposal of the excavated materials in the reservoir
as proposed does not negatively affect water quality within or downstream of the Cedar Cliff
Development. This request was initially made at a February 21, 2018 meeting with NCDWR,
NCWRC, USACE, and USFWS, where Duke Energy presented and discussed the results of its rock
spoil evaluation. To address this request, Duke Energy has developed a monitoring plan for the
auxiliary spillway upgrade to assess any direct changes in water quality of Cedar Cliff Lake or the
downstream reach due to pyrite oxidation. On May 29, 2018, the monitoring plan was provided to
USACE, NCDWR, and NCWRC for concurrence. The final monitoring plan, including
commencement of water quality monitoring in the summer of 2018, is being implemented by Duke
Energy pursuant to the Individual Permit and WQC issued by NCDWR for construction of the
auxiliary spillway upgrade is included in Appendix F.
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5.3 Fisheries and Aquatic Resources
5.3.1 Affected Environment
Because the required minimum flow will be maintained at the Cedar Cliff powerhouse throughout the
construction period, and the construction footprint is primarily limited to the reservoir, dam, and the
area immediately below the dam, the area of interest with respect to effects of construction on
fisheries and aquatic resources includes Cedar Cliff Lake and the upstream extent of the 0.46-mile-
long Bypassed Reach.
Cedar Cliff Lake is classified by the USFWS National Wetlands Inventory (NWI) as lacustrine,
limnetic, consolidated bottom, permanently flooded, diked/impounded (L1 UBHh). Shoreline habitats
along Cedar Cliff Lake include clay/weathered bedrock, sand/cobble, vegetated/stream confluence,
and woody debris. These habitats provide food and cover for aquatic fauna and critical nursery
areas for juvenile fish.
Cedar Cliff Lake exhibits a wide variety of warmwater and coolwater fish species. Fish survey data
for Cedar Cliff Lake collected in the 1960s and 1996 by the NCWRC identified 18 species, many of
which are game species such as smallmouth and largemouth bass (most common), and rainbow,
brown, and brook trout (FERC 2006). The reservoir is classified by the NCWRC as hatchery
supported trout waters. In 2018, Cedar Cliff Lake was stocked by NCWRC with rainbow trout.
Riverine habitat along the Cedar Cliff Bypassed Reach (East Fork Tuckasegee River downstream
from Cedar Cliff Dam to the powerhouses) includes riffle/run complexes and pools with a variety of
coarse substrate such as sands, cobbles, boulders, and bedrock. Organic aquatic habitats include
leaf packs, woody debris, root masses, and submerged/emergent vegetation. The riparian corridor is
intact and includes large trees and shrubs that provide shade and cover for aquatic organisms. The
Bypassed Reach is typically dry, as there are no substantial direct tributaries to this reach, with the
lowest portion of the Bypassed Reach receiving only 0.5 cfs of cumulative mean flow (FERC 2006).
Due to the primarily dewatered condition, historical sampling has indicated both low diversity and
abundance of the fish community in this reach. As part of the 2002 relicensing studies, Duke Energy
evaluated benthic m acroi nverteb rates at a sampling location on the East Fork approximately 1.5
miles downstream of the Cedar Cliff Dam that received a bioclassification of Good -Fair. A site
reconnaissance of the sampling location revealed no suitable mussel habitat or other evidence of
mussel occurrence.
5.3.2 Potential Environmental Effects
Potential impacts to fisheries and aquatic resources due to construction of the planned auxiliary
spillway upgrade and associated facilities may result from drawdown of the reservoir, physical
construction activities, and placement of excavated materials in Cedar Cliff Lake.
Cedar Cliff Lake will be drawn down 30 ft below the normal full pond elevation for approximately 25
months during construction activities. As water levels recede, aquatic organisms may become
stranded. Habitat within the drawdown zone will be unavailable for fish and other aquatic organisms.
The exposed habitat may undergo minor alteration during drawdown, but will quickly become
reestablished once the reservoir is refilled subsequent to construction activities. Exposed areas
include the upstream extent of Cedar Cliff Lake, which will be dewatered except for periods of power
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generation at Bear Creek (see the drawdown reservoir water surface map included as Attachment 1
of the Drawdown Plan in Appendix E).
Increases in suspended sediment associated with the planned construction could affect the aquatic
resources and may adversely affect aquatic habitat (when and if present) in the Bypassed Reach or
reservoir bottom by filling in pools and coarse substrate (i.e., gravel and cobble) habitats with fine-
grained material. However, any increases in turbidity are expected to be temporary and localized;
therefore, effects are anticipated to be negligible. As described below, increases in turbidity will be
controlled to the greatest extent possible through measures such as the ESC Plan and BMPs.
The placement of excavated materials from the auxiliary spillway excavation in Cedar Cliff Lake is
expected, based on consultation between Duke Energy and NCWRC, to create additional fish
habitat in the reservoir.
5.3.3 Proposed Mitigation Measures
As described in the Drawdown Plan (Appendix E) and Section 5.1.3, above, impacts of the
drawdown on fisheries and aquatic resources will be limited by lowering and refilling the reservoir at
a rate no greater than 3 ft per 24 hours on a continuous basis until the desired lake elevation is
achieved. During the reservoir drawdown process, Duke Energy will perform inspections of the
exposed shoreline areas for the occurrence of erosion or fish stranding in shallow lake areas. If
erosion or fish stranding is observed, Duke Energy will consult with the resource agencies to
determine if a decreased drawdown rate is necessary to reduce the likelihood of erosion or
strandings. Duke Energy has developed and will implement an ESC Plan and BMPs to minimize
impacts to water quality and aquatic resources. Following construction, all disturbed areas will be
restored and re -graded to pre -construction grades and re -vegetated with native vegetation.
5.4 Wetlands and Riparian Communities
5.4.1 Affected Environment
According to the NWI, reaches of the East Fork of the Tuckasegee River are identified as riverine,
upper perennial, rocky shore, temporary flooded (R3RSA) and riverine upper perennial,
unconsolidated bottom, and permanently flooded (R3UBH) (Cowardin et al. 1979). The East Fork
Tuckasegee River reach located within the vicinity of Cedar Cliff Dam is generally 20 to 40 ft wide
with stream bank heights ranging from 4 to10 ft. The riparian buffer is mostly intact with localized
areas of scour and stream bank erosion. The NWI classifies Cedar Cliff Lake as lacustrine, limnetic,
consolidated bottom, permanently flooded, and diked/impounded (L1 UBHh).
In September 2015, in support of the Section 404/401 permit application, Duke Energy contracted
with HDR to survey the work area and adjacent lands for wetlands and jurisdictional waters of the
U.S. under Section 404 of the CWA. The areas were examined according to the methodology
described in the USACE 1987 Wetland Delineation Manual (USAGE 1987), USACE Post-Rapanos
guidance, USACE Eastern Mountains and Piedmont Regional Supplement (USACE 2012), and
NCDWR Methodology for Identification of Intermittent and Perennial Streams and Their Origins
(Version 4.11) (NCDWR 2010).
On -site reconnaissance activities identified the East Fork Bypassed Reach and Cedar Cliff Lake as
jurisdictional waters. During a site visit in December 2015, the USACE verbally confirmed that they
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will not claim federal jurisdiction over aquatic habitats within the auxiliary spillway or the seep
drainage along the toe of the main dam. Table 5-2 provides a summary of jurisdictional waters of the
U.S. within the work area (i.e., boundary depicted on Appendix A, Figure 2).
Table 5-2.Summary of Jurisdictional Waters
35.251261 R3RSA/ * —2,000 linear feet
-83.100550 R3UBH
35.255780 L1 UBHh —121 acres
-83.096929
5.4.2 Potential Environmental Effects
Table 5-3 provides a summary of impacts to USACE jurisdictional waters.
Table 5-3.Impacts to Jurisdictional Waters Summary
Sheet 2
Cedar Cliff
Lake
Sheet 3
Cedar Cliff
Lake
Sheet 3
Cedar Cliff
Lake
Cedar Cliff
Sheet 6
Lake
Temporary Fill 0.5 acres
(Barge Loading Staging Area)
Permanent Fill 9.6 acres
(Spoil) 'm
Temporary 50.8 acres
(Dewatering)
Permanent Fill 0.01 acres
(Submerged Weir)
60.91 acres
As previously noted, Duke Energy has received an Individual Permit pursuant Section 404
(Appendix B) and WQC pursuant to Section 401 (Appendix C) of the Clean Water Act for these
impacts.
5.4.3 Proposed Mitigation Measures
Duke Energy has developed and will implement an ESC Plan and BMPs to minimize impacts to
wetland resources. Following construction, all disturbed areas will be restored and re -graded to pre -
construction grades and re -vegetated with native vegetation.
As required by Condition 6 of the WQC issued by NCDWR in December 2016, and as described
above, Duke Energy will develop and secure approval of an ESC Plan prior to commencing
drawdown of reservoir. ESC measures shall not be installed in wetlands or waters with the exception
of turbidity curtains. All ESC devices shall be removed and the natural grade restored. ESC
practices must be in full compliance with all specifications governing the proper design, installation
and operation and maintenance of such BMPs.
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Additionally, to prevent sedimentation in the upstream reservoirs from traveling into the downstream
reaches, the Individual Section 404 permit requires Duke Energy to employ all ESC measures to
prevent an increase in sedimentation or turbidity within waters/wetlands outside the permit area. This
shall include, but is not limited to, the immediate installation of silt fencing or similar appropriate
devices around all areas subject to soil disturbance or the movement of earthen fill, and the
immediate stabilization of all potentially disturbed areas. Additionally, the Project will remain in full
compliance with the Sedimentation Pollution Control Act of 1973 (North Carolina General Statutes
Chapter 113A Article 4). Prior to any excavated spoil repository work, Duke Energy will require the
contractor to install minimum 5-foot turbidity barriers with weighted skirts adjoining the repository
work areas that are in or adjacent to surface waters. The turbidity barriers shall stay in place until
work is complete and erodible materials have been stabilized.
5.5 Terrestrial and Wildlife Resources
5.5.1 Affected Environment
In 2015, in support of the proposed auxiliary spillway upgrade and the Section 404/401 permit
application, a botanical survey was conducted by for Duke Energy by HDR within the planned
construction footprint (work area). Based on Classification of the Natural Communities of North
Carolina — Fourth Approximation (Schafale 2012), several natural communities were identified
including Montane Acid Cliff, Acidic Cove Forest, and Rich Cove Forest.
The work area is dominated by hard and mixed hardwood pine forest types. The forested areas are
comprised of mature woody, herbaceous, and vine species including black oak (Quercus veluntina),
northern red oak (Quercus rubra), white oak (Quercus alba), American sycamore (Platanus
occidentalis), American beech (Fagus grandifolia), black walnut (Juglans nigra), black locust
(Robinia pseudoacacia), cucumber tree (Magnolia acuminate), green ash (Fraxinus pennsylvanica),
mockernut hickory (Carya tomentosa), persimmon (Diospyros sp.), tulip poplar (Liriodendron
tulipifera), hemlock (Tsuga canadensis), red maple (Acer rubra), striped maple (Acer
pensylvanicum), white pine (Pinus strobus), yellow birch (Betula alleghaniensis), black cherry
(Prunus serotina), chokecherry (Prunus virginiana), ironwood (Carpinus caroliniana), mountain
doghobble (Leucothoe fontanesiana), mountain laurel (Kalmia latifolia), spicebush (Lindera benzoin),
witchhazel (Hamamelis virginiana), yellowroot (Xanthorhiza simplicissima), bee balm (Monarda sp.),
cardinal flower (Lobelia cardinals), horsetail (Equisetum sp.), goldenrods, jack -in -pulpit (Arisaema
triphyllum), Nepalese browntop (Microstegium vimineum), wingstem (Verbesina alternifolia), ebony
spleenwort (Asplenium platyneuron), southern lady fern (Athyrium filix-femina), sensitive fern
(Onoc/ea sensibilis), catbrier (Smilax sp.), Japanese honeysuckle (Lonicera japonica), muscadine
(Vitis rotundifolia), poison ivy (Toxicodendron radicans), trumpet creeper (Campsis radicans), and
Virginia creeper (Parthenocissus quinquefolia).
Terrestrial communities are comprised of forested lands with a few open habitats that may support a
diverse number of wildlife species. Representative mammal, bird, reptile, and amphibian species
commonly occurring in these habitats are listed below. Note individual species and/or evidence of
species observed during HDR's field survey are indicated with an asterisk (*). Information on species
that typically use these habitats in the Appalachian Oak Forest Region was obtained from relevant
literature, mainly the Biodiversity of the Southeastern United States, Upland Terrestrial Communities
(Martin et al. 1993).
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Mammal species that commonly occur in these habitats include eastern cottontail
(Sylvilagusfloridanus); gray squirrel (Sciurus carolinensis); eastern chipmunk (Tamisstriatus),
southern flying squirrel (Glaucomysvolans), various vole, rat, and mice species; raccoon
(Procyonlotor); Virginia opossum (Didelphisvirginiana); white-tailed deer (Odocoileusvirginiana), and
black bear (Ursus americanus). Bird species that commonly use these habitats include indigo
bunting (Passerine cyanea), prairie warbler (Dendroica discolor), northern cardinal (Cardinalis
cardinalis), field sparrow (Spizella pusilla), rufous -sided towhee (Pipilo erythrophthalmus), red -eyed
vireo (Vireo olivaceous), scarlet tanager (Piranga olivacea), blue jay (Cyanocitta cristata), and
Carolina chickadee (Poecile carolinensis). Predatory birds may include several hawk and owl
species and turkey vulture (Cathartes aura). Reptile and amphibian species that may use this
terrestrial community include copperhead (Agkistrodon contortrix), eastern corn snake (Pantherophis
guttatus), eastern box turtle (Terrapene carolina carolina), eastern fence lizard (Sceloporus
undulatus), five -lined skink (Plestiodon fasciatus), spring peeper (Pseudacris crucifer), timber
rattlesnake (Crotalus horridus), and American bull frog (Rana catesbeiana). The dominant species of
salamander in these habitats are dusky salamanders (Desmognathus spp.).
5.5.2 Potential Environmental Effects
Minimal amounts of terrestrial vegetation will need to be cleared to expand the auxiliary spillway
channel and make other minor improvements to access roads. Improvements to access roads to
better facilitate construction activities will require removal of vegetation and ground disturbances, but
effects will be temporary and localized. Impacts of construction on sensitive species are addressed
in Section 5.6.
5.5.3 Proposed Mitigation Measures
Duke Energy has developed and will implement an ESC Plan and BMPs to minimize impacts to
terrestrial resources. Following construction, all disturbed areas will be restored and re -graded to
pre -construction grades and re -vegetated with native vegetation. Additionally, Duke Energy will cut
trees as needed in a manner that minimizes impacts to federally protected bat species, as discussed
in greater detail in Section 5.6.
5.6 Threatened and Endangered Species
5.6.1 Affected Environment
A list of federally protected species for Jackson County, North Carolina was obtained from the
USFWS website on April 24, 2018. Table 5-4 provides a summary of these species.
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Table 5-4. Federally Protected Species for Jackson County, North Carolina
C/emmys muhlenbergii
Glaucomys sabrinus coloratus
Myotis sodalis
Myotis septentrionalis
Myotis grisescens
Invertebrates
Alasmidonta raveneliana
Spruce -Fir Moss Spider . Microhexura montivaga
T(S/A) Probable/
Potential
MCurrent
E Current
T Current
E Current
E Current
E
Vascular Plants =�
Curren
M
W�� T Currant
T Current
E Current
E = Endangered. A taxon "in danger of extinction throughout all or a significant portion of its range."
T = Threatened. A taxon "likely to become endangered within the foreseeable future throughout all or a significant
portion of its range."
T(S/A) = Threatened due to similarity of appearance. A taxon that is threatened due to similarity of appearance with
another listed species and is listed for protection. Taxa listed as T(S/A) are not biologically endangered or
threatened and are not subject to Section 7 consultation.
2 Current = The species has been observed in the county within the last 50 years.
Probable/Potential = The species is considered likely to occur in the county based on the proximity of known
records (adjacent counties), the presence of potentially suitable habitat, or both.
An on -site survey to identify potential habitat and possible individuals of federally protected species
known to occur in Jackson County was conducted in preparation for the Section 404/401 permit
application. As part of this effort, HDR consulted the North Carolina Natural Heritage Program
(NCNHP) Element Occurrence database for protected species distribution and proximity to the
Cedar Cliff Development. The NCNHP database revealed no known occurrences of federally
protected species within the work area. The following is a summary of biological conclusions for
species that are protected under provisions of Section 7 and Section 9 of the Endangered Species
Act of 1973.
The site visit revealed no suitable habitat for the bog turtle, Carolina northern flying squirrel,
Appalachian elktoe, spruce -fir moss spider, small -whorled pogonia, swamp pink, or rock gnome
lichen within the work area. Potential roosting habitat for the Indiana bat and northern long-eared bat
was identified along the rock face of the auxiliary spillway and trees along the top of the ridge.
A database search conducted by the USFWS indicated no known northern long-eared bat occupied
hibernacula and maternity roost trees are located within close proximity of the work area. During a
site visit conducted by USFWS, Duke Energy, and HDR representatives on March 23, 2016, the
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USFWS determined that there is suitable habitat for federally protected bat species along the bluff of
the existing auxiliary spillway. USFWS recommended a summer acoustic survey to be conducted to
determine the presence and/or absence of Indiana bat and northern long-eared bat within an
approximate 3-acre proposed blasting and clearing area required for the auxiliary spillway
modifications.
5.6.2 Potential Environmental Effects
Minimal amounts of terrestrial vegetation will need to be cleared to expand the auxiliary spillway
channel and make other minor improvements to project access roads. Additionally improvements to
access roads to better facilitate construction activities may require removal of vegetation. Vegetation
removal (i.e. tree clearing) could have effects on the Indiana bat and northern long-eared Bat;
however, Duke Energy has consulted with appropriate agencies and will implement protective
measures for the protection of federally listed bat species during the planned construction.
A study plan following the 2016 Rangewide Indiana Bat Summer Survey Guidelines was developed
for Duke Energy and submitted to USFWS for approval on April 25, 2016, as part of the Section
404/401 permit process. A bat acoustic survey was conducted for Duke Energy during the summer
survey window (May 16 to May 18) at two locations for two nights each to determine the presence
and/or probable absence of Indiana bats and northern long-eared bats within the proposed blasting
and clearing area. Bat calls were analyzed using two software programs approved by the USFWS:
BCID and EchoClass. Ten bat species were initially identified by the acoustic analysis programs. A
total of five Indiana bat and eight northern long-eared bat call files were identified. A report detailing
the findings of the bat acoustic survey was submitted electronically to the USFWS on June 13, 2016
(HDR 2016). After reviewing the report, USFWS confirmed that the survey results indicated both
species (Indiana bat and northern long-eared Bat) were present within the work area. Duke Energy
subsequently submitted mitigation measures to minimize adverse impacts. Provided that all of the
mitigation measures are implemented, the USFWS concurred with a "may affect, not likely to
adversely affect" determination for the federally listed bat species.
5.6.3 Proposed Mitigation Measures
Duke Energy proposes to cut trees within the 3-acre blasting and clearing area from October 15 —
April 15 to avoid impacts to the maternity roosting period for federally protected bat species. The
USFWS will be notified if (unplanned) trees need to be removed during the summer maternity roost
season. In this situation, an experienced biologist will conduct an on -site habitat assessment to
determine if trees to be cleared are suitable roosts (i.e. live trees and/or snags that have exfoliating
bark, cracks, or crevices). If potential roosts are identified, emergence surveys will be conducted at
nighttime, before trees/snags are removed. If emergence surveys indicate federally protected bats
use those trees, the USFWS will be contacted to establish a plan for proceeding prior to tree
removal. Additionally, potential suitable roost trees adjacent to the work area will be marked and
protected during clearing activities.
5.7 Historic and Archaeological Resources
5.7.1 Affected Environment
In association with the 2004 East Fork Project FERC license application, Duke Energy
commissioned a National Register evaluation of Project facilities and an archaeological survey.
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Based on this evaluation, project facilities at the Cedar Cliff Development were determined to be
eligible for the National Register since the development is an element of the larger Nantahala area
hydropower system. In addition, the Project is eligible under the categories of Industry and Military.
In the 1950s, electricity generated by the Project was used by the Alcoa Corporation to meet the
growing need of aluminum during the Korean Conflict and the Cold War's operations in eastern
Tennessee. An archaeological survey was conducted in portions of the Project identified by the
NCSHPO, Forest Service, and EBCI THPO as having potential to contain historic properties. Phase I
archaeological surveys were completed along the shorelines of Bear Creek Lake, Wolf Creek Lake,
and the Tanasee Creek Lake during a 10-ft drawdown. A survey of Cedar Cliff Lake was not
performed as part of the evaluation.
As required by license Article 414, Duke Energy maintains and implements an HPMP for the Project.
The HPMP provides measures to avoid, minimize, and mitigate adverse effects on historic properties
from Project operation.
The HPMP includes special provisions associated with large, planned, extended drawdowns, which
is defined as any planned drawdown where the pond elevation will remain at least 10 ft below the
normal minimum elevation for a minimum of 30 consecutive days. Specifically, the provision states
that in the event of a large, planned, extended drawdown, the Licensee will consult NCSHPO and
EBCITHPO regarding the need to conduct archaeological surveys of the exposed area.
5.7.2 Potential Environmental Effects
As described in Section 4, and due to the extent of the planned reservoir drawdown, Duke Energy
initiated consultation with NCSHPO and EBCI THPO regarding the proposed construction activities
and reservoir drawdown. Pursuant to the requirements of the HPMP, Duke Energy sent a letter
dated August 5, 2016 to the NCSHPO and EBCI THPO providing notification and description of the
planned construction activities and associated drawdown at the Cedar Cliff Development. No
response was received by Duke Energy from the EBCI THPO. Via letter to Duke Energy dated
August 30, 2016, NCHPO indicated it is unlikely that any archaeological resources that may be
eligible for inclusion in the NRHP will be adversely affected by the planned construction activities
and drawdown.
5.7.3 Proposed Mitigation Measures
In accordance with the HPMP, in the event that previously unknown archaeological or historic sites
are identified during the course of the reservoir drawdown, Duke Energy will notify the NCSHPO and
ECBI THPO as soon as possible, not to exceed 10 days following the day that Duke Energy
becomes aware of the previously unknown site. Duke Energy will propose a management plan for
the site in consultation with the NCSHPO and EBCI THPO.
Additionally, in the event that a previously unknown archaeological or historic site is discovered
during the course of construction activities, Duke Energy will halt construction and initiate
consultation with the NCSHPO and EBCI THPO. If advised by the NCSHPO or EBCI THPO, Duke
Energy will ensure that a qualified archaeologist assesses the newly discovered site to determine if it
is eligible for the NRHP. If the site is found to be a Historic Property (i.e., eligible or potentially
eligible for the NRHP), Duke Energy will enter into consultation with NCSHPO and EBCI THPO to
determine the appropriate course of action.
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5.8 Recreation Resources and Land Use
5.8.1 Affected Environment
As described in Section 2.3, the FERC Project boundary around the Cedar Cliff Development
encompasses two formal public recreation sites, the Cedar Cliff Access Area, located on Cedar Cliff
Lake, and the Shook Cove Access Area, located downstream of the powerhouses (Appendix A,
Figure 3).
The Cedar Cliff Lake Access Area, which is maintained through a cooperative maintenance
agreement between Duke Energy and NCWRC, currently provides a boat ramp, pier, seasonal
portable toilet, and parking. The site is maintained in accordance with the approved Recreation Plan
for the Project, which was filed with FERC by Duke Energy on December 19, 2011 (supplemented
March 5, 2012) and approved by FERC by order dated November 27, 2012.
5.8.2 Potential Environmental Effects
The planned construction activities are not anticipated to have any effect on the Shook Cove Access
Area.
As described in the Cedar Cliff Lake Drawdown Plan (Appendix E), the Cedar Cliff Access Area will
not be open during construction, as the boat ramp will be unusable during the reservoir drawdown.
The site will remain closed until Cedar Cliff Lake returns to elevation 2,323 ft AMSL or greater.
5.8.3 Proposed Mitigation Measures
Pursuant to the requirements of the FERC-approved Recreation Plan and associated agreement
with the NCWRC, and as noted in the Drawdown Plan (Appendix E), Duke Energy has coordinated
with the NCWRC for methods for closure of the Cedar Cliff Lake Access Area. As mitigation for this
impact, NCWRC requested that Duke Energy use this opportunity to perform additional maintenance
at the site, including paving and limited removal of accumulated sediment under dewatered/dry
conditions. Flow from Kiesee Creek has eroded the existing floating boat dock and sediment has
been deposited in the shallow portion of the reservoir. Duke Energy plans (subject to the terms of
the amended Section 404 and Section 401 Individual Permit issued by USACE and NCDWR) to
excavate the excess sediment from the reservoir to elevation 2,322 ft msl, with all excavated
material to be deposited in upland areas. Installation of a permanent rock vane is proposed to deflect
flow from Kiesee Creek away from the boat launch.
6 Consideration of License Requirements
6.1 License Articles
Standard License Articles 2 and 3, Articles 202 (Exhibit F Drawings) and 203 (Exhibit G Drawings),
and Article 305 (As -Built Drawings)
License Articles 3, 202, and 203 require the licensee to maintain the project work in conformity with
the approved exhibits and that changes to exhibits (A, F, and G) be approved by the FERC. License
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Article 303 requires the licensee to file within 90 days after construction is complete, revised Exhibits
A, F, and G (as applicable) for FERC approval to show the project facilities as -built.
The modifications to project works that will occur as part of the auxiliary spillway upgrade project
have been designed in consultation with and as directed by the FERC ARO to satisfy safe passage
of the IDF without overtopping Cedar Cliff Dam. Following the completion of construction activities,
Duke Energy will file with the FERC revised/as-built Exhibits A, F, and G to reflect permanent
modifications to project works of Cedar Cliff Development.
Article 302 — Contract Plans and Specifications
License Article 301 requires that the licensee submit one copy of the final contract plans and
specifications and supporting design report to FERC ARO and two copies to the FERC at least 60
days prior to construction. The submittal must include a Quality Control and Inspection Program, a
Temporary Construction Emergency Action Plan, and an ESC Plan. The licensee cannot begin
construction until the FERC ARO has reviewed and commented on the plans and specifications,
determined that all pre -construction requirements have been satisfied and authorized the start of
construction.
Duke Energy submitted final contract plans and other submittal requirements to the FERC ARO on
March 18, 2019. Construction will not begin until all pre -construction requirements are met and the
FERC ARO has authorized the start of construction.
Article 401— Reservoir Level Management
License Article 401 requires the licensee to operate the Cedar Cliff Development according to the
reservoir level management provisions, as required by Condition 6 of the [2010] WQC to protect the
aquatic and recreation resources in the Tuckasegee River and to provide downstream flows.
Pursuant to Article 401 and WQC Condition 6, the Normal Operating Range for Cedar Cliff Lake is
2,326 to 2,330 ft AMSL year-round.
General requirements for temporary variances in lake level requirements are addressed in the Hydro
Project Maintenance and Emergency Protocol, which is included as Appendix A in the East Fork
License. Due to the extended duration of the planned reservoir drawdown, Duke Energy is seeking
approval from the FERC for a temporary variance from the requirements of Article 401 in order to
hold the reservoir level at approximately 2,300 ft AMSL for the duration of the required drawdown
period to complete construction activities at the Cedar Cliff Development. The Cedar Cliff Lake
Drawdown Plan included as Appendix E has been developed in consultation with the NCWRC,
USFS, USFWS, and NCDWR.
Article 402 — Recreation Plan
License Article 402 requires the licensee to file with the FERC for approval within one year of license
issuance, a Recreation Plan for the East Fork Hydroelectric Project to enhance the recreation
resources at the Project. Duke Energy filed a Recreation Plan with the FERC for approval on
December 19, 2011, which was supplemented on March 5, 2012. On November 27, 2012, the FERC
issued an Order Modifying and Approving the Recreation Plan.
Cedar Cliff Access Area is currently maintained through a cooperative maintenance agreement with
NCWRC signed on June 5, 2008. Per the 2008 agreement, if it becomes necessary to temporarily
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close any Public Access Area or any portion thereof (e.g. if a lake level is too low to safely use the
access area), written notice shall be provided through electronic mail or by letter to the other party of
such condition, and the Parties will jointly determine the appropriate course of action, including
methods for closure, and public notification. Duke Energy is currently working with the NCWRC
regarding the impacts to the Cedar Cliff Access Area during construction activities.
Temporary impacts to and proposed mitigation measures for the Cedar Cliff Access Area due to the
reservoir drawdown are addressed in Section 5.8.
Article 403 — Public Information at East Fork Project
License Article 403 requires the licensee to continue to provide information on its website and
telephone system in regards to reservoir levels and recreation flows for Cedar Cliff Lake.
Duke Energy will continue to provide information related to the schedule and associated impacts of
the Cedar Cliff Lake drawdown on the existing Duke Energy website (httl)s://www.duke-
energy.com/community/lakes) and telephone system.
Article 404 — Minimum Flows and Flow Monitoring Plan
License Article 404 (as amended) requires the licensee to release minimum flow from the Cedar Cliff
reservoir, as required by WQC Condition 6, consisting of a flow during non -generation hours of 10
cfs from December 1 through June 30 and 35 cfs from July 1 through November 30, or during low
inflow periods a flow of 6 cfs from December 1 through June 30 and 11 cfs from July 1 through
November 30, each year, from the Cedar Cliff Development to the East Fork of the Tuckasegee
River.
Duke Energy will continue to provide the minimum flows from the Cedar Cliff Development required
by Article 404 and WQC Condition 6 and pursuant to the East Fork Minimum Flow/Flow Monitoring
Plan approved by FERC by order dated March 2, 2012. As described in the approved Minimum
Flow/Flow Monitoring Plan, the minimum flow is provided through the minimum flow turbine installed
in 2013, which is capable of meeting the full range of flows required by License Article 404. For any
periods when the minimum flow turbine is not available, the minimum flow will be provided over the
principal spillway.
In the event the required minimum flows cannot be provided during the drawdown period due to low
inflow, Duke Energy will provide written notification pursuant to the FERC-approved Minimum Flow
and Flow Monitoring Plan and Low Inflow Protocol.
Article 405 — Recreation Flow
License Article 405 requires the licensee to operate the East Fork Project in coordination with the
West Fork Project to provide scheduled recreation flow releases into the main stem of the
Tuckasegee River during the recreation season. As described and required by the East Fork
Minimum Flow/Flow Monitoring Plan approved by the FERC by order dated March 2, 2012, the East
Fork Project is operated (1) in accordance with the Normal Generation Schedule to Support
Recreation to facilitate the preferred angling flow of at or below 500 cfs vicinity of the Dillsboro
section of the Tuckasegee River during the Primary Angling Periods defined in the license, and (2) at
or above best efficiency flow in support of boating target flows of about 800 cfs in the vicinity of the
Dillsboro section of the Tuckasegee River during the Primary Boating Periods defined in the license.
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The annual schedule for East Fork Project recreation releases is developed according to License
Article 405 and in consultation with recreation stakeholders.
The auxiliary spillway upgrade is not expected to impact normal generation at the developments of
the East Fork Project. Additionally, in the event that the East Fork Project is unavailable to operate to
facilitate the downstream required recreation flows, license Article 405 allows for the requirements to
be met with flow releases from the West Fork Project. Duke Energy therefore expects to continue to
provide the recreation flows into the Tuckasegee River during the recreation season, throughout the
duration of the drawdown and construction activities.
Article 408 — Shoreline Management Plan
License Article 408 requires the licensee to file for FERC approval a Shoreline Management Plan
(SMP), to be developed in consultation with USFWS, NCWRC, and NCSHPO, to protect the scenic
quality and environmental resources at the Project area. Duke Energy filed the SMP with FERC for
approval on June 29, 2012, which was supplemented on August 31, 2012. On February 20, 2014,
FERC issued an Order Modifying and Approving the SMP.
The proposed drawdown and construction activities are not expected to result in any permanent
changes to the Shoreline Management Plan and are consistent with the approved SMP. The work
area shown in Appendix A, Figure 2 is encompassed primarily within areas classified in the SMP as
"Project Operations."
Article 409 - Sediment Management Plan
License Article 409 (and Condition 6 of the 2010 WQC) requires the licensee to implement a
Sediment Management Plan, to be prepared in consultation with USFWS, NCWRC, USACE, and
NCDWQ, for mechanical removal of sediment/drawdown of Project reservoirs. The Sediment
Management Plan is to include a provision for best management practices to control sedimentation
in the reservoirs upstream of the Cedar Cliff dam from entering the downstream reaches; a provision
for dredging that shall include measures to minimize the impact of the project drawdown and
sediment removal on environmental resources; and an implementation schedule.
As described throughout the current document, no mechanical removal of sediment from Cedar Cliff
Lake is proposed as part of the auxiliary spillway upgrade or associated construction or reservoir
drawdown activities. Sediment management related to short-term construction impacts of these
activities is addressed through the requirements of the Section 404 Individual Permit issued by
USACE and the Section 401 WQC issued by NCDWR for construction. As required by Condition 6 of
the construction (i.e., 2016) 401 WQC, Duke Energy must develop and secure approval of an ESC
Plan prior to commencing drawdown of the reservoir. To prevent sedimentation in the upstream
reservoirs from traveling the downstream reaches, the Individual Section 404 permit issued by
USACE further requires Duke Energy to employ all ESC measures to prevent an increase in
sedimentation or turbidity within waters/wetlands outside the permit area. This shall include, but is
not limited to the immediate installation of silt fencing or similar appropriate devices around all areas
subject to soil disturbance or the movement of earthen fill, and the immediate stabilization of all
disturbed areas. Additionally, the Project will remain in full compliance with the Sedimentation
Pollution Control Act of 1973 (North Carolina General Statutes Chapter 113A Article 4).
Duke Energy developed a Cedar Cliff Lake Drawdown Plan (Appendix E) describing the drawdown
and refill rate, schedule, public outreach, and sediment and erosion control measures associated
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with the drawdown. On December 15, 2016, the draft Drawdown Plan was provided for 30-day
review to NCDWR, NCWRC, and USFWS, and each agency provided comments. Duke Energy
incorporated the comments received into the Drawdown Plan, as applicable. An updated version of
the draft Drawdown Plan is being distributed to these same agencies for final review and
concurrence. The final Drawdown Plan including the consultation record and a summary of the
comments received and how they were addressed is provided in Appendix E. The Drawdown Plan
provides a robust set of measures and procedures for the protection of natural resources to minimize
potential impacts associated with reservoir drawdown.
Article 414 — Programmatic Agreement
License Article 414 requires the licensee to implement the "Final Programmatic Agreement Among
the Federal Energy Regulatory Commission and the North Carolina State Historic Preservation
Officer for Managing Historic Properties that may be Affected by a License Issuing to Duke Power
Company, LLC for the Continued Operation and Maintenance of the East Fork Hydroelectric Project
in Jackson County, North Carolina," executed on September 19, 2006, and including but not limited
to the approved HPMP, filed August 7, 2006, for the Project.
Compliance with the HPMP is addressed in Section 5.7.
6.2 U.S. Forest Service 4(e) Conditions
The East Fork Project occupies 23.15 acres of the Nantahala National Forest administered by the
USFS, which is adjacent to the Bear Creek and Tennessee Creek developments. The USFS filed
one final section 4(e) condition on June 19, 2006. The final term and condition is set forth in
Appendix B of the 2011 New License and incorporated into the license by Ordering Paragraph E and
summarized below.
The Forest Service condition 1 requires Duke to provide a minimum flow of 6 cfs into the Wolf Creek
Bypassed Reach between Wolf Creek dam and Tennessee Creek powerhouse from Jan 1 to Dec
31, subject to provisions of the Low Inflow Protocol and the HPMEP.
The Cedar Cliff Development auxiliary spillway upgrade project will have no effect on Duke Energy's
ability to comply with the 4(e) conditions for the East Fork Project.
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7 References
Byerly, D. W. 1996. Handling acid -producing material during construction: Environmental and
Engineering Geoscience, Volume II, pp. 49-57.
Byerly, D. W. 1990. Guidelines for Handling Excavated Acid -Producing Materials: U. S. Department
of Transportation, Federal Highway Administration, Publication No. DOTFHWA-FL-007,
Washington, DC, 82p.
Cowardin, L.M., Carter, V., Golet, F.C., and LaRoe, E.T. 1979. Classification of Wetlands and
Deepwater Habitats of the United States. U.S. Fish and Wildlife Service, Washington, D.C.
Federal Energy Regulatory Commission (FERC). 2006. Preliminary Final Environmental
Assessment for Hydropower Licenses, Nantahala East Projects, North Carolina. FERC
Office of Energy Projects, Division of Hydropower Licensing, Washington, DC. July 2006.
HDR. 2016. Indiana and Northern Long -Eared Bat Acoustic Survey Report, Cedar Cliff Development
Spillway Upgrade Project. Jackson County, North Carolina, June 13, 2016: Report for Duke
Energy of the Carolinas, LLC
2017. Geological and Geotechnical Subsurface Investigation, East Fork Hydroelectric Project
and Cedar Cliff Development (FERC No. 2698).Tuckasegee, North Carolina, Report for
Duke Energy of the Carolinas, LLC.
2018a. Cedar Cliff Rock Spoil Evaluation, East Fork Hydroelectric Project and Cedar Cliff
Development (FERC NO. 2698). Tuckasegee, North Carolina, January 4, 2018: Report for
Duke Energy of the Carolinas, LLC.
2018b. Cedar Cliff Hydroelectric Development Auxiliary Spillway Upgrade Project Status
Update and Permitting Process. Power Point Presentation for Agency Briefing January 18,
2018.
Martin, W.H., Boyce, S.G., and Echternacht, A.C.1993. Biodiversity of the Southeastern United
States, Upland Terrestrial Communities. S ponso red by the Southeastern Chapter of the
Ecological Society of America.
Nantahala Power and Light. 2000. FERC Relicensing First Stage Consultation Package. East Fork
Hydroelectric Project, FERC Project No. 2608-NC
North Carolina Division of Water Resources (NCDWR). 2010. Methodology for Identification of
Intermittent and Perennial Streams and Their Origins (Version 4.11).
Schafale, M.P. 2012. Guide to the Natural Communities of North Carolina — Fourth Approximation.
(http://cvs.bio.unc.edu/pubs/4thApproximationGuideFinalMarch2Ol2.pdf)
U.S. Army Corps of Engineers (USACE). 2012. Regional Supplement of the Corps of Engineers
Wetland Delineation Manual: Eastern Mountains and Piedmont Region (Version 2.0). U.S.
Vicksburg, Mississippi. April 2012.
(http://www.usace.army.miI/Portals/2/docs/civilworks/regulatory/req supp/EMP Piedmont v
2b.pd )
1987. Wetland Delineation Manual. Vicksburg, MS.
May 2019 1 30

Environmental Report
Cedar Cliff Auxiliary Spillway Upgrade
Annp-nriiy C.
May 2019 1 C-1

PAT MCCRORY
37ONALD R. VAN .DER VAART
DWR # 2016-0742 reissuance
Jackson. County .
Due Energy Carolinas, LLC
Attn: Mr. Jonathan Wise
400 S. Church St
Charlotte NC 28202
Subject: Approval of Individual 401 Water Quality Certification with Additional Conditions
'Cedar Cliff Development Auxiliary Spillway Upgrade Project
USAGE Action ID. Na. SAW-20.15-025.43
........
Dear Mr. Wise:
Attached hereto is a copy of Certification No. WQC004077 issued to Mr. Jonathan Wise and
Duke Energy Carolinas, LLC, dated December 6, 2016. This Certification replaces the
Certification issued on November 10, 2016 to account for additional open water impacts
from the 1951 Access Road Connection. Please note that you should get any other federal,
state or local permits before proceeding with the subject project, including those required
by (but not limited to) Sediment and Erosion Control, Non -Discharge, and Water Supply
Watershed regulations.
This approval and its conditions are final and binding unless contested. This Certification
can be contested as provided in General Statute 150E by filing a written petition for an
...........
administrative hearing to the Office of Administrative Hearings (hereby known as OAH)
within sixty j60j calendar days. ...................
A petition form maybe obtained from the OAH at htt : www.ncoah.corn or by calling the
OAH Clerk's Office at [phone] for information. A petition is considered filed when
the original and one [1) copy along with any applicable OAH filing fee is received in the OAH
during normal office hours (Monday through Friday between 8:00am and 5:00pm, excluding
official state holidays).
The petition may be faxed to the OAH at [phone], provided the original and one copy.of
the petition along with any appIicab€e OAH filing fee is received by the OAH within five. (5)
business. days following the faxed transmission.
Bute 0 NL)T le Carolina - Niv ironttoentaI Quit iity ; W;' t-,r Resources
1617 MaiS scnice enter Raleigh, lvottll C aaralini 27699-1617
979 807 6300
�?3x;'?'��s�f4;1.�Sr1�1:-�`�`•L1y_3i���1`���:?iFf4�dix'.3�'Y", ?3„�r"." .

Cedar Cliff D-evelopment Auxiliary $plllwaw upgrade Prcpject
DWR N 16-07 relssvance
Individual Certification #4077
Page 7 of 7
Mailing ,Wre5s for the OAH-
If sen ding u40 US Plastof Service.
Office of Ad m i n i strat ive H ear-lin 5
6714 Mail Service Center
If sendixiq vier d0very 5Ervice (UPS,
fedEX, Ott);
Office of Ad m i nistrat ive Hearings
1711 New Hope Church RDa4
Raleigh, NC 27699-6714 Raleigh, NC 2 76 -6285
one Ill copy of th-e petition My S1 a Iso be served to DEQ_
Sam Hayes, General C€runwl
De.part ment of E nvI re rrmenta I Quality
1601 Mail Service Center
Raleigh, NC 27699-16D1
Unless such a petition is filed, th1s Certificati cn sha I I b e fi n a 1 a nd h I ndirkg,
This c-ertif}-cation com plete 5 t he review of t he Dlaisloh Und or sect ion 40 1 of t he Cl ea n Wat e r A(; t
arnd ISA NCAC D2 H , 0500. Contact Su a Homewood at 336-776-9693 or
sue, hom ewood @ ncclen r-gov if you h ave ally q uestion s or con Berns.
Si ncerelV,
Karen Ai ins, S upervi 50
401 & Buffer Permitting Branch
cc; Mr. Erie MI ularskir H DR Engineering Inc, (via email)
David grown, UMCE AsheviRe Regulato rV Fieild Off Ice
Todd Bower% EPA, Sam N ur n Federal Center, 61 Forsyth Street SW, Atiant@, GA 9030a
DWR W SRQ 401 file
Fi 1-a Cop* (Laserfich e)
rilert8 me: i�lj��?��d�r�liff$�d Fway(lacksanj AOi IC reissue
C-3

Cedar Cliff Development Auxiliary Spillway Upgrade Project
DWR # 16-0742 relssuance
Individual Certification ##4077
.Page 3 of 7
NORTH CAROLINA 401 WATER QUALITY CERTIFICATION
CERTIFICATION #WQC004077 is issued in conformity with the requirements of Section 401,
Public Laws 92-500 and 95-217 of the United States and subject to North Carolina's Regulations in
15A NCAC 02H .0500, to Mr. Jonathan Wise and Duke Energy Carolinas, LLC, who have
authorization for the impacts listed below, as described within your application received by the
N.C. Division of Water Resources (Division) on July 29, 2016 with additional information received
October 20, 2016, and November 15, 2016, and by Public Notice issued by the U. S. Army Corps of
Engineers and received by the Division on August 12, 2016.
The State of North Carolina certifies that this activity will not violate the applicable portions of
Sections 301, 302, 303, 306, 307 of the Public Laws 92-500 and PL 95-217 if conducted in
accordance with the application, the supporting documentation, and conditions hereinafter set.
forth.
This approval requires you to follow the. conditions.listed in the certification .below.
Conditions of Certification:
1. The following impacts are hereby approved provided that all of the other specific and
general conditions of the Certification are met. No other impacts are approved, including .
incidental impacts. [15A NCAC 02H A506(b) and/or (c))
Type. of Impact
Amount Approved
Amount Approved
(units)
(units)
Permanent
i Temporary
Stream
I Site 1
0 (linear feet)
110 (linear feet)
Open Waters
Site OW1 m
0 (acres)
E 0.5 (acres)
Site OW2
9.6 (acres)
0 (acres) -�
-
Site OW3
0 (acres)
50.8 (acres)
— _
Site OW4
_
0.01 (acres)
0 (acres)
Site OW5 —1951
0.22 (acres)
0 (acres)
access connector rd
2. The NC Wildlife Resource Commission (NCWRC) shall be consulted to determine the
preferred rock spoil locations within the lake.
3. A reservoir drawdown plan shall toe provided. to the Division for approval 3Q calendar days
prior to submittal to FERC....................... ..... .... . . ... ..................................
.................................................................................... ................... ............................
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Cedar Cliff Deveiopmern.AuxiIlia ry 5pi€Tway Upgrade Project
DWR # 16-0742 reissuance
Individual Certification #i4077
Page 4 of 7
4. The Permittee shall maintain compliance with all conditions of DWR Certification No. 3831
(DWR Project #2003-1112).
5. No waste, spoil, solids, or fill of any kind shall occur in wetlands, waters, or riparian areas
beyond the footprint of the impacts depicted in the Pre -Construction Notification €or this
project. All construction activities, including the design, installation, operation, and
maintenance of sediment and erosion control Best Management Practices shall be
performed so that no violations of state water quality standards, statutes, or rules occur.
Approved plans and specifications for this project are incorporated by reference and are
enforceable parts of this permit. [15A NCAC 02H .0501 and .0502]
6. The Permittee shall secure approval of an Erosion and Sediment Control Plan prior to
commencing drawdown of the water level in the reservoir. Sediment and erosion control
measures shall not be installed in wetlands or waters with the exception of turbidity
curtains. All sediment and erosion control devices shall be removed and the natural grade
.................. .
restored within two (2) months of the date that the Division of Energy, Mineral and Land
Resources (DEMI_R) has released the specific area within the project. [15A NCAC 02H .0501
and ,0502]
7. Erosion and sediment control practices must be in full compliance with all specifications
governing the proper design, installation and operation and maintenance of such Best
Management Practices. if applicable, the project must comply with the specific conditions
and requirements of the NPDES Construction Stormwater Permit issued to the site and the
following requirements [15A NCAC 02H .0506(b)(3) and (c)(3)):
a. Design, installation, operation, and maintenance of the sediment and erosion
control measures must be such that they equal or exceed the requirements specified
in the most recent version of the North Carolina Sediment and Erosion Control .........
Manual. The devices shall be maintained on all construction sites, borrow sites, and
waste pile (spoil) projects, including contractor -owned or ]eased borrow pits ...................
associated with the project.
b. For borrow pit sites, the erosion and sediment control measures must be designed,
installed, operated, and maintained in accordance with the most recent version of
the North Carolina Surface Mining Manual.
c. Reclamation measures and implementation must comply with the reclamation in
accordance with the requirements of the Sedimentation Pollution Control Act and
the Mining Act of 1971.
d. Sufficient materials required for stabilization and/or repair of erosion control
.measures and star uvater routing and treatment shall be on site at all times,
................. ............................................................................... ...........................:.
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Cedar Cliff Development.Auxiiiary Spillway Upgrade Project
DwR # 16-0742 reissuance
Individual Certification #4077
Page S of 7
6. An NPDES Construction Stormwater Permit is required for construction projects that disturb...
one (1) or more acres of land. This Permit allows stormwater to be discharged during land ..........
disturbing construction activities as stipulated in the conditions of the permit. if your ................
project is covered by this permit, full compliance with permit conditions including the
erosion & sedimentation control plan, inspections and maintenance, self -monitoring, record
keeping and reporting requirements is required. A copy of the general permit
(NCG010000), inspection log sheets, and other information may be found at:
hit : deg, nc.ov about divisions ener -mineral-land-resources enemy-rriireral-iand-
ermits starn�water- ermits construction-svv. 15A NCAC 02H .0506(b)(5) and (c)(5)]
7. All work in or adjacent to stream waters shall be conducted so that the flowing stream does
not come in contact with the disturbed area. Approved best management practices from the
most current version of the NC Sediment and Erosion Control Manual, or the NC DOT
Construction and Maintenance Activities Manual, such as sandbags, rock berms, cofferdams,
and other diversion structures shall be used to minimize excavation in flowing water. (15A
NCAC 02H .0506(b)(3) and (c)(3)]
S. if concrete is used during the construction, then all necessary measures shall be taken to
prevent direct contact between uncured or curing concrete and waters of the state. Water
that inadvertently contacts uncured concrete shall not be discharged to waters of the state
due to the potential for elevated pH and possible aquatic life/fish kills. [15A NCAC 02B .0200)
9. Temporary culverts required for this project shall be installed in such a manner that the
original stream profiles are not altered and to allow for aquatic life movement during low ....
flows. Existing stream dimensions (including the cross section dimensions, pattern and
longitudinal profile) must be maintained above and below locations of each culvert.
10. All temporary fill and culverts shall be removed and the impacted area returned to natural
conditions, within 60 days of the determination that the temporary impact is no longer
necessary. The impacted areas shall be restored to original grade, including the stream's
...............::
original cross sectional dimensions, plan form pattern, and longitudinal bed and bed profile,
and the site shall be stabilized with natural woody vegetation (except approved maintenance
areas) and restored to prevent erosion. [15A NCAC 02H .0506(b)(2) and (c)Q)]
11. All temporary pipes/culverts/riprap pads etc, shall be installed in all streams as outlined in the
most recent edition of the North Carolina Sediment and Erosion Control Planning and Design
Manual so as not to restrict stream flow or cause dis-equilibrium. [15A NCAC 02H .05060)(2)
and (G.)21.
....................................................................................................................................
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Cedar Cliff Development Auxiliary Spillway Upgrade Project
DWR # 16-0742 reissuance
Individual Certification #4077
Page 6 of 7
12. Any riprap required for proper culvert placement, stream stabilization, or restoration of
temporarily disturbed areas shall be restricted to the area directly impacted by the approved
construction activity. All riprap shall be buried and/or "keyed in" such that the original ................
stream elevation and streambank contours are restored and maintained. Placement of riprap
or other approved materials shall not result in de -stabilization of the stream bed or banks
upstream or downstream of the area, [15A NCAC 02H .0506(b)(2)]
13. Any riprap used for stream stabilization shall be of a size and density to prevent movement by
wave action, current action, or stream flows and consist of clean rock or masonry material
free of debris or toxic pollutants. Riprap shall not be installed in the streambed except in
specific areas required for velocity control and to ensure integrity of bank stabilization
measures. [15A NCAC 02H .0506(b)j2)]
14. This Certification does not relieve the applicant of the responsibility to obtain all other
required Federal, State, or Local approvals.
................
15. Mr. Jonathan Wise and Duke Energy Carolinas, LLC shall conduct construction activities in a
manner consistent with State water quality standards (including any requirements resulting
from compliance with section 303(d) of the Clean Water Act) and any other appropriate
requirements of State and Federal law. [15A NCAC 02B .0200] if the Division determines that
such standards or laws are not being met (including the failure to sustain a designated or
achieved use) or that State or federal law is being violated, or that further conditions are
necessary to assure compliance, the Division may reevaluate and modify this Certification.
Before modifying the Certification, the Division shall notify Mr. Jonathan Wise and Duke
Energy Carolinas, LLC and the U.S. Army Carps of Engineers, provide public notice in
accordance with 15A NCAC 02H .0503 and provide opportunity for public hearing in
accordance with 15A NCAC 02H .0504. Any new or revised conditions shall be provided to
Mr. Jonathan Wise and Duke Energy Carolinas, LLC in writing, shall be provided to the U.S.
Army Corps of Engineers for reference in any Permit issued pursuant to Section 404 of the ........
Clean Water Act, and shall also become conditions of the 404 Permit for the project. ............
16. This approval is for the purpose and design described in your application and as described in
the Public Notice. The plans and specifications for this project are incorporated by reference
and are an enforceable part of the Certification. if you change your project, you must notify
the Division and you may be required to submit a new application package with the
appropriate fee. if the property is sold or transferred, the new owner must be given a copy of
this Certification and is responsible for complying with all conditions. Any new owner must
notify the Division and request the Certificationbe issued in their name. [15A NCAC 02H
.0501 and ..050Z] ................................ .. ....................

Cedar Cliff Deweloprn ent Auxillpry 5pillw&y Up8r2de Project
DWR If 1"742 reissuarlee
Ind iwidui)l CertiFcation 4r4O77
Page 7 of 7
17. Th a a pp I ican t an d/or a uM o rued ape nt sh a I I p rcivide a cornpi Eted Ce rtifl Cate of Corn PI eti o n
For rn to the DW R 401 & 8 uffer Perm itti ng U nit with i n to n days -of p rojed co rn plet ion
(avail -able at: htt = r5edenr_s3.amazoaaws.comJs3fs-
yu bk/WatetIP OCIuality/Su rfa ce%2 OW ater%20Protecti on 14O 1/Cens%20an d%2 OF-erm itVCe r
t ifrcate0fComR Ietio o f eb 2 015. d-oc ). 115A N CHIC 0 2 H ,0502�f)] -
18, Th i s certificati o n grant s perm'$Sign to th e D irs�to r o r a rr aut hor i71=d ri-p rL-,;Fn rat ive of lh e
Di rector, u pon t h e p resentati o n of prope r cre derlti a I s, t o e n ter the prope rty du ring n orma I
Business hours. (15A NCAC 02H .05-02(e)]
Th is ap prowa I to proceed with -you r proposed Fm pact5 or to co ncfuct i M pacts to avaters as
depicted i ri your application shall expire upon expiration of the 404 permit, The con d it ions in
effect o n the d ate o f issoerrce sh a I I rem atn in effect for t h e li fe -of th a project, rega rdiess of the
exp iration date of t his Certifi ratio n_ J15A N CAC 02H .0507� d �J 2) and 15A NCAC 02 H -05061
N orr-corn p I iance with or viol ation of th a con-ditio ns he rein set forth m ay result in revoc ation of
th i 5 Certificat ion arh d rrray a Iso resu It i n cri m i rwal a rid/or c ivi I pe n alti es,
This the 9th d-ay of December, 201.6
Ire rk H ilggin 5, Su pe rhriso
40 1 & Buffe r Pe rrn it ti ng Bran ch
KAHIsh
VVQCO04O77
C-8

Environmental Report OR
Cliff Auxiliary Spillway Upgrade
May 2019 1 E-1

Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Hydroelectric Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
1.0 INTRODUCTION
The East Fork Hydroelectric Project (Project) is owned and operated by Duke Energy Carolinas, LLC
(Duke Energy) under a license issued by the Federal Energy Regulatory Commission (FERC) on
May 4, 2011.' The Project consists of three hydroelectric developments which include, from
upstream to downstream, Tennessee Creek (includes the Wolf Creek Dam and the Tanasee Creek
Dam), Bear Creek, and Cedar Cliff. The Cedar Cliff Development includes Cedar Cliff Dam located
on the East Fork of the Tuckasegee River near river mile (RM) 52.1 in Jackson County, North
Carolina. The FERC Project boundary for the East Fork Project encompasses approximately 1,462
acres, including 23.15 acres of the Nantahala National Forest administered by the U.S. Forest
Service (USFS) adjacent to the Bear Creek and Tennessee Creek Developments.
Via letter dated April 24, 2014, the FERC Atlanta Regional Office (ARO) required Duke Energy to
satisfy safe passage of the Inflow Design Flood (IDF), which is defined as the Probable Maximum
Flood (PMF), without overtopping Cedar Cliff Dam. The proposed remedial alternative to safely pass
the PMF involves modifications to the existing auxiliary spillway channel, installation of a Fusegate
system within the auxiliary spillway control section, placement of an 8.5-foot (ft)-high concrete
parapet wall along the crest of the dam, and other appurtenant components. Related activities will
include the new redundant hoist installation at the principal spillway, Tainter gate maintenance,
powerhouse transformer replacement, new access road construction and modifications to an
existing private access road, construction of a new principal spillway bridge, and construction of an
approximately 0.5-acre laydown area at the upstream approach channel to the auxiliary spillway.
In order to complete the aforementioned work, Cedar Cliff Lake will need to be drawn down
approximately 30 feet from Full Pond Elevation (Attachment 1) for the duration of construction
(anticipated to be approximately 25 months). In accordance with the Hydro Project Maintenance &
Emergency Protocol (HPMEP) for the Project (Appendix A of the license order), Duke Energy has
prepared this Drawdown Plan to describe the procedures and schedule associated with the Cedar
Cliff Lake drawdown and measures to maintain compliance with the state water quality certification,
FERC license and associated plans, and the Tuckasegee Cooperative Stakeholder Team
Settlement Agreement, as applicable. Under a separate cover letter, Duke Energy has consulted
Duke Energy Carolinas, LLC, 143 FERC 162,203 (2013).
E-2

Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
with the North Carolina State Historic Preservation Office (NCSHPO) and the Eastern Band of
Cherokee Indians Tribal Historic Preservation Officer (EBCI THPO) regarding measures to be taken
for extended drawdowns (Attachment 2).
Duke Energy is submitting this Drawdown Plan to FERC for approval as part of a request for a
temporary variance of the reservoir elevation requirements for the Cedar Cliff Development,
pursuant to Article 401 of the Project license. As explained below in Section 4.1, this approval is
being requested by Duke Energy because the proposed drawdown is outside of the typical
maintenance activities or circumstances established by the Low Inflow Protocol and the Hydro
Project Maintenance & Emergency Protocol.
2.0 PROJECT DESCRIPTION
The Cedar Cliff Development consists of a 590-foot-long, 173-foot-wide, earth -and -rock fill dam with
a crest elevation of 2,343.5 feet above mean sea level (ft AMSL). The dam impounds Cedar Cliff
Lake with a surface area of 121 acres and approximately five miles of shoreline at Full Pond
Elevation 2,330 ft AMSL. A principal spillway with one Tainter gate is located at the right abutment of
the dam. An auxiliary spillway with two erodible fuse plug sections is located at the left abutment of
the dam. Water is conveyed to the Cedar Cliff powerhouses via a tunnel intake opening near the
right upstream toe of the dam and travels down the 1, 1 38-foot-long power tunnel and penstock. The
main powerhouse contains one vertical Francis -type generating unit with an installed capacity of
8,187 horsepower (hp) and a hydraulic capacity of 555 cubic feet per second (cfs). In 2012, Duke
Energy installed a new minimum flow unit, which is housed in a new small powerhouse adjacent to
the main powerhouse and has nameplate -rated capacity of 526 hp and a hydraulic capacity of 35
cfs. Cedar Cliff Dam creates a 0.46-mile-long Bypassed Reach from the base of the dam to the
Cedar Cliff powerhouse discharge and back to the East Fork Tuckasegee River. No continuous
minimum flow from the reservoir is provided to the Bypassed Reach.
Operation of the upstream Tennessee Creek and Bear Creek Developments is coordinated with the
operation of the Cedar Cliff Development. The Tennessee Creek and Bear Creek powerhouses
typically operate during the afternoon to support system loads and to refill Cedar Cliff Lake for off-
peak generation and water releases. Water from Tanasee Creek Lake and Wolf Creek Lake is
released downstream into Bear Creek Lake. Water is released from the Bear Creek Powerhouse to
Cedar Cliff Lake. Cedar Cliff Lake is normally operated between elevations 2,330 ft AMSL and 2,326
ft AMSL year-round, with a normal target elevation of 2,328 ft AMSL.
E-3

Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
The FERC Project boundary around Cedar Cliff Lake encompasses the dam and reservoir, the
Project structures, the Bypassed Reach, and two formal public recreation sites, the Cedar Cliff
Access Area, located on Cedar Cliff Lake, and the Shook Cove Access Area, located downstream of
the powerhouses. Operation and maintenance of both sites are provided by the North Carolina
Wildlife Resources Commission (NCWRC). No federal lands are included in the FERC Project
boundary for the Cedar Cliff Development.
3.0 DRAWDOWN PLAN
3.1 Drawdown and Refill Rate
Cedar Cliff Lake will be drawn down to approximately 2,300 ft AMSL (30 ft below Full Pond Elevation
2,330 ft AMSL) to allow for the new redundant hoist instal lation/Tainter gate maintenance and
construction of the auxiliary spillway upgrade. Cedar Cliff Lake elevation will be lowered by releasing
flows through the generating units at a rate no greater than three feet per 24 hours (average of 0.13
ft per hour) on a continuous basis until the desired lake elevation is achieved. During the reservoir
drawdown process, Duke Energy will perform inspections of the exposed shoreline areas for the
occurrence of erosion or fish standing in shallow lake areas. If erosion or fish stranding is observed,
Duke Energy will consult with the resource agencies to determine if a decreased drawdown rate is
necessary to reduce the likelihood of the erosion or stranding to occur.
Cedar Cliff Lake will be held at approximately 2,300 ft AMSL for the duration of construction activities
by releasing flows through the generating units or over the principal spillway. In the event of Cedar
Cliff Development inflow exceeding approximately 590 cfs or the available powerhouse capacity,
inflow will be passed over the sill of the principal spillway (elevation 2,305 ft AMSL), as the Tainter
gate will remain in a partially open condition throughout construction .
Upon completion of construction activities, Cedar Cliff Lake will be refilled based on inflows, but at a
rate no greater than three feet per 24 hours (average of 0.13 ft per hour) on a continuous basis until
the Normal Target Elevation (i.e., 2,328.0 ft AMSL) is achieved.
3.2 Schedule
Duke Energy anticipates the duration of construction activities at the Cedar Cliff Development will be
approximately 25 months, with construction planned for September 2019 through September 2021.
To facilitate the start of construction in early September 2019 (post Labor Day weekend), the Cedar
Cliff Lake drawdown will begin on September 3, 2019, and the refill will begin in October 2021.
E-4

Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
3.3 Public Outreach
Based on the duration and extent of the Cedar Cliff Lake drawdown, Duke Energy will perform public
outreach measures to notify land owners abutting Cedar Cliff Lake and primary lake users of the
planned drawdown. Duke Energy public outreach will include the following:
■ Provide information related to the schedule and associated impacts of the Cedar Cliff
Lake drawdown on the existing Duke Energy Lakes & Recreation website and telephone
system;
■ Post a sign(s) at the Cedar Cliff Lake Access Area notifying users of the schedule of the
drawdown and associated impacts and restrictions;
■ Provide written notification of the drawdown to land owners abutting the Cedar Cliff Lake
including information for an appropriate contact at Duke Energy to report concerns;
■ Provide written notification of the drawdown to primary lake users such as local
recreation outfitters;
■ Coordinate with the NCWRC pursuant to the existing agreement between Duke Energy
and the NCWRC;
■ Assist the NCWRC with external communications regarding any NCWRC activities or
schedules for 2019 through 2021 that will be impacted by the drawdowns; and
■ Provide press releases in local news outlets.
In addition to the measures listed above, Duke Energy provided preliminary notification of the planned
drawdown to affected homeowners and via local news outlets in the fall of 2018.
3.4 Sediment and Erosion Control
Sediment and erosion control measures will be implemented and maintained, as necessary, per the
requirements of the state water quality certification and to maintain compliance with the state water
quality standards, statutes, or rules.
During drawdown and immediately after the drawdown elevation is reached at each facility,
inspections will be performed by Duke Energy once per week and after significant rainfall events
(e.g., precipitation estimates for the Project area of 1 inch or greater within 24 hours), as feasible.
Approximately one month after the drawdown is reached and based on the condition of the exposed
lake bottom, inspections will occur at least monthly for the duration of the drawdown. Inspections will
identify mass wasting and sloughing on the banks and remediation measures will be installed as
needed. Remedial measures may include installation of straw bales along the banks or similar
E-5

Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
measures to decrease velocity of waters, decrease erosion, and minimize the amount of sediment
released to Cedar Cliff Lake through erosion. Erosion control materials (i.e., straw bales) will be
available onsite in the event such materials need to be rapidly deployed via barge.
4.0 LICENSE COMPLIANCE
4.1 Article 401 — Reservoir Level Management
License Article 401 requires Duke Energy to operate the Project according to specific reservoir level
management provisions, as required by Condition 6 of the North Carolina water quality certification
to protect the aquatic and recreational resources in the Tuckasegee River and to provide required
downstream flows. More specifically, the Licensee is required to maintain the elevation of the Project
reservoirs between the designated Normal Minimum and Normal Maximum elevations (2,326 ft
AMSL and 2,330 ft AMSL, respectively), except when the Licensee is permitted to vary from the
Normal Operating Range as established in the Low Inflow Protocol (as outlined in Appendix A of the
license order) and in the HPMEP (also included in Appendix A of the license order).
The reservoir level requirements may be temporarily modified from the Normal Operating Range if
required by conditions beyond the control of the Licensee, for short periods during annual inspection
and repair events, or by operating emergencies or maintenance needs as defined in the Low Inflow
Protocol and the HPMEP. If operations or reservoir levels are so modified, the Licensee shall notify
the FERC as soon as possible, but no later than 10 days after each such incident, and shall provide
the reason for the change in reservoir levels.
Consistent with the consultation requirement of the HPMEP, Duke Energy has prepared this Cedar
Cliff Lake Drawdown Plan in consultation with the NCWRC, the United States Fish and Wildlife
Service (USFWS), and the North Carolina Division of Water Resources (NCDWR). An early draft of
the Drawdown Plan was distributed for review in December 2016. The Drawdown Plan has been
revised to incorporate comments received from this review, as well as applicable comments received
during the 2017-2018 consultation process for the East Fork Project Comprehensive Drawdown Plan
for Required Maintenance Activities in 2018-2019. Updated versions of this Drawdown Plan were
re -distributed to the NCWRC, USFWS, and NCDWR for review and concurrence in August 2018 and
May 2019, prior to being submitted to the FERC with the original and updated requests for approval
of a temporary variance of the reservoir elevation requirements for the Cedar Cliff Development.
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Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
4.2 Article 402 — Recreation Plan
Under License Article 402, Duke Energy has prepared and maintains a Recreation Plan for the
Project, which was approved by FERC by order dated November 27, 2012. As described in the
Recreation Plan, with respect to the Cedar Cliff Development, a single formal recreation access area
is maintained by Duke Energy in partnership with NCWRC at Cedar Cliff Lake, the Cedar Cliff
Access Area. As stated above and in the Recreation Plan, the Cedar Cliff Development includes one
recreation area, the Cedar Cliff Lake Access Area that provides a boat ramp, pier, seasonal portable
toilet, and parking. Duke Energy does not currently charge a fee for public use of the access area
facilities, which are open for use at all times. The Cedar Cliff Lake Access Area is currently
maintained through a cooperative maintenance agreement with NCWRC.
The boat ramp at the Cedar Cliff Access Area will be unusable during the drawdown. The 30-foot
drawdown described in this plan will result in closure of the Cedar Cliff Access Area when Cedar Cliff
Lake reaches elevation 2,323 ft AMSL. The site will remain closed until Cedar Cliff Lake returns to
elevation 2,323 ft AMSL or greater. Pursuant to the requirements of the FERC-approved Recreation
Plan and associated agreement with the NCWRC, Duke Energy will coordinate with the NCWRC for
methods for closure of the Cedar Cliff Lake Access Area and public notification during the drawdown
period. As mitigation for the approximately 25-month closure of this facility, NCWRC requested that
Duke Energy use this opportunity to perform additional maintenance at the site, including paving and
limited removal of accumulated sediment under dewatered/dry conditions. Flow from Kiesee Creek
has eroded the existing floating boat dock and sediment has been deposited in the shallow portion of
the reservoir. Duke Energy plans to excavate the excess sediment from the reservoir to elevation
2,322 ft msl, with all excavated material to be deposited in upland areas. Installation of a permanent
rock vane is proposed to deflect flow from Kiesee Creek away from the boat launch.
4.3 Article 403 — Public Information at East Fork Project
In accordance with the requirements of License Article 403, Duke Energy will continue to provide
information on its website and telephone system regarding reservoir levels and recreation flows for
Bear Creek, Cedar Cliff, Wolf Creek, and Tanasee Creek Lakes.
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Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
4.4 Article 404 — Minimum Flow
License Article 404 (as amended)z requires the licensee to release minimum flow from the Cedar
Cliff reservoir to the East Fork of the Tuckasegee River, as required by Condition 6 of the North
Carolina water quality certification, which consists of 1) during non -generation hours, a flow of 10 cfs
from December 1 through June 30, and 35 cfs from July 1 through November 30, or 2) during low
inflow periods3, a flow of 6 cfs from December 1 through June 30, and 11 cfs from July 1 through
November 30. Duke Energy expects to continue to provide the required minimum flow from the
Cedar Cliff Development throughout the duration of the drawdown.
In the event the required minimum flows cannot be provided during the drawdown period due to low
inflow, Duke Energy will provide written notification pursuant to the FERC-approved Minimum Flow
and Flow Monitoring Plan and Low Inflow Protocol.
4.5 Article 405 — Recreation Flow
License Article 405 requires the Licensee to operate the East Fork Project to provide scheduled
recreation flow releases at or above the best efficiency flow of the Cedar Cliff unit into the main stem
of the Tuckasegee River during the recreation season. Throughout the duration of the drawdowns
described herein, Duke Energy will continue to provide recreation flows required by Article 405.
4.6 Article 414 — Programmatic Agreement
License Article 414 requires the licensee to implement the "Final Programmatic Agreement Among
the Federal Energy Regulatory Commission and the North Carolina State Historic Preservation
Officer for Managing Historic Properties that may be Affected by a License Issuing to Duke Power
Company, LLC for the Continued Operation and Maintenance of the East Fork Hydroelectric Project
in Jackson County, North Carolina," executed on September 19, 2006, and including but not limited
to the approved Historic Properties Management Plan (HPMP), filed August 7, 2006, for the Project.
The 2006 HPMP includes special provisions associated with large, planned, extended drawdowns,
which is defined as any planned drawdown where the pond elevation will remain at least 10 feet
below the Normal Minimum Elevation for a minimum of 30 consecutive days. Specifically, the
provision states that in the event of a large, planned, extended drawdown, the Licensee will consult
with the North Carolina State Historic Preservation Office (NCSHPO) and the Eastern Band of
2 Duke Energy Carolinas, LLC, 138 FERC 162,146
3 As defined by the Low Inflow Protocol (Appendix A of the license order)
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Duke Energy Carolinas, LLC
East Fork Hydroelectric Project (P-2698)
Cedar Cliff Development Auxiliary Spillway Upgrade Project
Cedar Cliff Lake Drawdown Plan (2019 Update)
Cherokee Indians (EBCI) Tribal Historic Preservation Office (THPO) regarding the need to conduct
archaeological surveys of the exposed area
Pursuant to the requirements of the 2006 HPMP, Duke Energy sent a letter dated August 5, 2016 to
the NCSHPO and EBCI THPO providing notification and description of the planned construction
activities and associated drawdown at the Cedar Cliff Development. No response was received by
Duke Energy from the EBCI THPO. Via letter dated August 30, 2016, the NCSHPO indicated it is
unlikely that any archaeological resources that may be eligible for inclusion in the National Register
of Historic Places will be adversely affected by the planned construction activities and drawdown.
The NCSHPO requested that Duke Energy take photographs to document the current condition of
the dam and its surroundings pursuant to their guidelines. Duke Energy is in the process of
completing the photographic documentation of the Cedar Cliff Dam and its surroundings pursuant to
the NCSHPO's request and guidelines. Copies of the above -referenced letters are provided in
Attachment 2.
Duke Energy also distributed a copy of the East Fork Project Comprehensive Drawdown Plan for
Required Maintenance Activities in 2018-2019 (including a 10-foot drawdown of Cedar Cliff Lake) to
the NCSHPO and EBCI THPO, to provide notification and description of the planned activities and
associated drawdowns at the Bear Creek, Cedar Cliff, and Tennessee Creek Developments and
initiate consultation regarding the need to conduct archaeological surveys of the exposed area. By
letter to Duke Energy dated October 23, 2017, NCSHPO stated that they had conducted a review of
the Project and are aware of no historic resources that would be affected, and therefore NCSHPO
has no comments on the proposed activities. No response was received from EBCI THPO, so,
consistent with Chapter 4 of the 2006 HPMP, Duke Energy therefore assumed concurrence with
Duke Energy's determination of no effect and that no additional surveys are required.
5.0 CONSULTATION
On December 15, 2016, Duke Energy provided a draft of this Drawdown Plan for 30-day review to
NCDWR, NCWRC, and USFWS, all of which provided comments on the draft plan. Duke Energy
incorporated the comments received into this Drawdown Plan, as applicable. A summary of the
comments received and how they were addressed as well as the record of consultation is provided
in Attachment 3.
Duke Energy provided an updated draft version of this Drawdown Plan to the aforementioned parties
for 30-day review in August 2018 (no additional comments were received) and May 2019.
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Environmental Report OR
Cliff Auxiliary Spillway Upgrade
May 2019 1 F-1

Cedar Cliff Hydroelectric Development Auxiliary Spillway Upgrade Project
Proposed Duke Energy Water Quality Monitoring Plan
Project Overview
In 2014, the FERC established the Inflow Design Flood (IDF) for Cedar Cliff development as
the Probable Maximum Flood (PMF). Prior to the FERC notice, the OF had been 40
percent of the PMF. The existing spillway discharge capacity is insufficient to pass the PMF
without overtopping the dam and resulting in potential failure of the structure. Engineering
design efforts are underway to expand the existing auxiliary spillway (width and depth) and
install Hydroplus-Fusegates as the control section. In addition, the existing parapet wall will
be replaced with a PMF Wall to create additional storage for the Cedar Cliff
reservoir. Studies have indicated the expanded auxiliary spillway, Fusegates, and PMF
Wall provide the necessary measures to safely pass the OF without overtopping Cedar Cliff
Dam.
The construction project is scheduled to begin July, 2019 and be completed December,
2020. The present plan specifies excavating material (approximately 283,200 cubic yards)
from the mountain hillside east of the current fuse plug (Figure 1). A gravel filter berm at the
lower end of the auxiliary spill channel will provide sediment and erosion control from the
excavations.
During construction, the lake will be lowered 30 ft to accommodate the construction activities
including staging the excavated material on the foot print of the existing fuse plug approach
channel. The excavated material will be loaded onto barges and spoiled into Cedar Cliff
Lake upstream of the dam (Figure 2) (for discussion and review of submerged disposal, see
HDR 2018a). As specified in the USACE 404/401 permit, a 3-5 ft floating turbidity barrier will
be installed at all work areas that are in, or adjacent to surface waters.
As discussed by HDR (2018a), pyrite (FeS2) was identified in rock exposures at the site and
in the rock core from boreholes drilled for the subsurface investigation (HDR 2017).
Subsequent petrographic analyses of metasedimentary rocks of the Tallulah Falls Formation
(TFFm) collected from the rock cores found that the garnet mica schist, mica schist, and
schistose biotite gneiss lithologies contained 2 percent to 7 percent pyrite by volume (HDR
2017). Based on the boreholes drilled during the geological/ geotechnical site investigation
for the Auxiliary Spillway upgrades, approximately 26 percent of the total excavated material
(73,600 cubic yards) will be made up of these three rock lithologies.
Even though there are no known instances of acid -drainage related to the metasedimentary
rocks of the TFFm in the region surrounding the site; rocks with greater than 1 percent pyrite
and/or pyrrhotite by volume are considered to be potentially acid -producing. Pyrite can react
in the presence of atmospheric oxygen and water to form ferrous sulfate and sulfuric acid
(2FeS2 + 702 + 2H2O -> 2FeSO4 + 2H2SO4). The stoichiometry of complete oxidation of one
mole of pyrite would produce 4 equivalents of hydrogen ions. Although some acid -drainage
is produced by natural weathering, construction activities can expose large volumes of rock
containing sulfide minerals to oxidizing conditions. The oxidation of pyrite and subsequent
acid production increase significantly when exposed to atmospheric oxygen and particle size
becomes smaller and smaller (Pugh et.al. 1984). Subsequent leaching of the oxidation
products by rainfall/groundwater result in the formation of acid drainage which is
F-2

Proposed Duke Energy Monitoring Plan
characterized by low pH values, high concentrations of sulfate, and mobilization of metals
such as iron, aluminum, and manganese.
Bosch and Meckenstock (2012) have suggested anaerobic nitrate -dependent microbial
pyrite oxidation may also contribute to acid production. Geochemical and stable isotope field
data from anaerobic aquifers indicate that denitrification was associated with pyrite
oxidation. Laboratory studies were more ambiguous, but suggested that this process may
occur under some conditions. The molecular mechanism of pyrite oxidation coupled with
denitrification is not well understood.
Factors affecting the amount of Acid -Production
• Percent Pyrite in Rock
• Morphology and grain size of the iron sulfide minerals
• Particle size of excavated material (surface area of disturbed or spoiled rock)
• Presence of certain iron bacteria (primarily Thiobacillus ferrooxidans)
• Presence of alkalinity producing material
• Oxygen concentration
• Nitrate
In addition to the factors affecting the amount of acid production, the characteristics of
Cedar Cliff Reservoir (Table 1) also influence the amount of oxidation products in the
reservoir and downstream reaches. For example, the wide range of pH values reflected the
poor buffering capacity of the low alkalinity water as biological activity metabolized carbon
dioxide. In addition, the very low ionic strength, as measured by conductivity, also influenced
the ability to measure accurate pH values as well as indicating the poor buffering capacity.
The relatively high oxygen concentrations in the lake would favor higher rates of pyrite
oxidation, but these rates would be very low compared to exposure to atmospheric oxygen.
The low nitrate concentrations would limit the amount of de -nitrification associated with
anaerobic nitrate -dependent microbial pyrite oxidation. Probably the most significant factor
limiting the accumulation of pyrite oxidation products in the lake is the very high flushing rate
of the reservoir (Table 1). The average retention time of the water at full pool is 15.3 days;
at a 30 foot drawdown the average retention time of the water is reduced to 8.1 days. Also,
at the 30 foot drawdown, the only way to maintain the lake level is by the hydro operation,
which draws water from the bottom of the lake further reducing the accumulation of
oxidation products in the lake.
Even though HDR (2017), HDR (2018a), and HDR (2018b) have discussed the project in
detail and have projected minimum, if any, acidification impacts from pyrite oxidation, and
the lake characteristics also suggest a lack of accumulation of acidic water, the potential
does exist for an alteration of the water quality. The proposed monitoring program is
designed to assess any direct changes in water quality due to pyrite oxidation.
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Proposed Duke Energy Monitoring Plan
Table 1. Cedar Cliff Reservoir Characteristics
Parameter Units
Full Pond (Spillway Elevation)
2330 ft-msl
Tainter Gate Elevation
2305 ft-msl
30 Foot Drawdown Elevation
2300 ft-msl
Cedar Cliff Hydro intake Elevation
2202 ft-msl
Proposed Elevation of Top of Rock Spoil
2250 ft-msl
Lake Volume below Full Pond
6320 ac-ft
Lake Volume below Tainter Gate
3742 ac-ft
Lake Volume below 30 foot drawdown
3386 ac-ft
Lake Volume below hydro intake
42 ac-ft
Mean Outflow'
209.0 cfs
Mean Retention Time (full pond)
15.3 days
Mean Retention Time (30 foot drawdown)
8.1 days
Max Depth at Dam (full pond)
148 ft
Max Depth mid -lake sampling (full pond)
106 ft
pH range2
5.7-8.0
Mean Alkalinity2
0.13 meq/1
Conductivity Range2
14-20 uSi
Mean Oxygen below 2250 ft-ms12
7.8 mg/l
Minimum observed oxygen2
4.2 mg/l
Mean Nitrate2
0.019 mg/l
1 Calculated from Cedar Cliff operations (1953-2013)
2 from NCDENR data reported in NP&L (2000)
Figure 1. Cedar Cliff Spill Channels and Proposed Excavation and Construction Areas with
Proposed Water Quality Sampling Sites (pink circles)
Page 3 of 8
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Proposed Duke Energy Monitoring Plan
Figure 2. Bathymetric Map of Cedar Cliff Reservoir Showing the Proposed Spoil Areas, the Hydro Intake, and the Downstream
Reach with Proposed Water Quality Sampling Sites (red circles)
i Ii ceaarC-rraowemouseTunnel Mlet Cedar Cliff Lake $athymetry
a I 2o�G Feel 14-Foot C oatows
I I I I I{ I I i I i i i i i i i i I h ��,a„QL aye n LS E— hG MM.
:o3-Jrab S-%mLr'?;o .Ca " Slat Pae NNMB LE 8w&Y Poor htWCrnher �9:5
Page 4 of 8
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Proposed Duke Energy Monitoring Plan
Cedar Cliff Monitoring Rationale
Most environmental monitoring programs directly assess water quality or employ various
indices for biological impacts, usually macroi nve rte b rates in streams. The proposed
water quality assessment is designed to directly address the potential impact of the rock
spoil in the reservoir, the spill channel, and the Tuckasegee River below the excavation
site.
The biological communities, particularly macro -invertebrates, are influenced by many
factors and rarely exhibit a direct cause and effect of a perturbation. He et.al. (2015),
Svitok et.al. (2014), Gray and Delaney (2008), and DeNicola and Stapleton (2016) have
reviewed the use of macro -invertebrate communities to assess acid mine drainage with
mixed results. Unless the pH was extremely low or significant iron oxide precipitation
was covering the substrates, many diversity indices, biological integrities, density and
taxonomic diversities, and various community metrics applied to macroinvertebrate
populations showed highly variable results in streams with acid -mine drainage.
The NCDENR (2011) reported good to excellent benthic communities in streams with
low pH (mean 5.98, range 5.4-6.9). These data suggest that the use of benthic
communities to assess the impact of low pH values was limited. Macro -invertebrate
communities are extremely difficult to assess in the deeper portions of reservoirs and are
probably non-existent in the dry spill channel. Cedar Cliff hydro discharge into the
riverine habitat is very different than the Lake Habitat downstream of Bear Creek Hydro.
For these reasons, macro -invertebrate assessments are not recommended to monitor
potential impacts from potential pyrite oxidation at Cedar Cliff.
Unlike biological assessments, water quality measurements specifically designed to
detect any chemical alterations have the advantage of:
• Direct correlation to pyrite oxidation
• Relatively rapid analysis of data
• Trends are readily assessed
• Various oxidation and acidification pathways are directly elucidated
• Treatment options (if necessary) may be evaluated and tested during the
excavation process rather than relying on long-term mitigation
Each water sample would measure the reactants and products of the pyrite oxidation
reactions. These analyses will be used to document the pH and pyrite oxidation
products in the lake, area leachates, and de -nitrification prior to and during the
construction project.
In addition to periodic water sampling, continual recording of conductivity would provide
a record of overall ionic change in the water. If oxidation products (ions) increase, the
very low conductivity of the Cedar Cliff water should reflect an increase in the ionic
strength and provide a record of the degree of change (if any).
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Proposed Duke Energy Monitoring Plan
Chemical Basis for Water Quality Monitoring
Major pH Buffering in Surface Water (Alkalinity): (Stamm and Morgan, 1981)
H20<=> H+ + OH-
0O2 + H20<=> H2CO3 <=> H+ + HC031- <=> H+ + C032
Chemistry of Pyrite Oxidation (Stumm and Morgan, 1981)
Pyrrhotite reacts with oxygen and water to produce reduced iron and sulfuric acid
Fe(1-x)S + (2-0.5x)02 + xH20=> (1-x)Fe2+ + SO42- + 2xH+
Pyrite reacts with oxygen and water to produce reduced iron and sulfuric acid
2FeS2 (s) + 702 + 2H2O => 2Fe2+ + 4SO42- + 4H+ [2FeSO4 + 2H2SO4]
Reduced ferrous iron reacts with oxygen and acid to produce Ferric iron
(rate limiting except if biologically catalyzed)
Fee+ + 1 /402 + H+ => Fe3+ + 1 /2H2O
Ferric Iron reacts with water to form iron hydroxide (yellow -red precipitate) and acid
Fe3+ + 3H2O => Fe(OH)3 (s) + 3H+
Excess ferric iron reacts with pyrite and water to form ferrous iron and sulfuric acid
FeS2 (s) +14Fe3+ + 8H2O => 15Fe2+ + 2SO42- + 16H+
Table 2. Proposed Chemical Analysis of Water Samples Pending Detailed Review of
Procedures to Achieve Low Limits of Detection
Parameter
Chemical
Tentative Analytical Method
Field Analysis Lab Analysis
Symbol
Whole Water Sample
Alkalinity
HC031- C032-
n/a-
Titration (0.025N HCI),
Inflection end -point
Total Iron
Fe
n/a--
Digestion, ICP
Raw Water, ICP
Aluminum
Al
n/a-
Raw Water, ICP
Manganese
Mn
n/a-
Raw Water, ICP
Calcium
Cat+
n/a-
Raw Water, ICP
pH
H+
Low conductivity
- n/a-
electrodes
Turbidity
n/a
Hach 2100Q Portable
n/a-
Turbidimeter
Ferrous Iron
Feel
1, 10 Phenanthroline
n/a-
colorimetric
Iron Hydroxide
Fe(OH)3
absorbance
n/a-
Field Filtered Water Sample
Nitrate -Nitrite
NO3'—NO21-
n/a-
Colorimetric
Sulfate
SO42-
n/a-
Low level
ion chromatography
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Proposed Duke Energy Monitoring Plan
Water Quality Monitoring Program
The water quality monitoring program is divided into two phases, namely the reservoir
sampling and the spill channel sampling. The reservoir sampling is designed to evaluate
the slower pyrite oxidation rates due to lower oxygen concentrations associated with the
large particle spoil on the bottom of the lake and the suspension of small particles
washed off the larger rocks as they are put in the lake. The spill channel sampling is
designed to evaluate the expected higher oxidation rates due to the high oxygen content
of the atmosphere and the higher surface to volume ratios of the fine particles in the
excavated area. These fine particles would be suspended and transported down the
auxiliary spill channel during rain events.
Cedar Cliff Reservoir Samolin
Monthly 1-meter profiles of Temperature, Dissolved Oxygen, Conductivity, pH, and
turbidity will be collected with a Hydrolab sonde fitted with a low ionic strength pH
reference electrode. The 1-meter profiles would be taken in the reservoir at the deepest
point in the vicinity of the Cedar Cliff hydro intake (see Figure 2) and at the deepest
point, approximately 2000 feet up -stream of the in -lake spoil footprints. Water samples
(Table 2) would be taken one meter above the lake bottom and one meter from the
surface. An additional water sample would be taken from a depth corresponding to
either abnormally high turbidity or abnormally low pH values in the water column.
Additional monthly water samples would be taken in the immediate tailrace of Cedar Cliff
Hydro and, as recommended by the USACE, just upstream of the East Fork/West Fork
confluence. A recording Hobo© fresh water conductivity data logger will be placed in the
Cedar Cliff Tailrace for the duration of the project.
Cedar Cliff Spill Channel Sampling
Since the spill channel is normally dry, but does serve as a conduit for water runoff
during rain events, the water sampling has to be conducted while the channel has runoff
water in it. Therefore, the water samples would be taken during runoff events of inch
of rain or more per 24-hours (Figure 1). A continuous recording water level sensor and
a recording conductivity sensor will be placed in the auxiliary spill channel upstream of
the sediment berm location prior to excavation'. The data from a recording rain gage
located on Cedar Cliff dam will be correlated with the continuous water level data from
the auxiliary spill channel. After the sediment berm is installed, a second set of water
level and conductivity sensors will be added downstream of the berm. The data will
document runoff events with the associated ionic strength throughout the project.
Data Review and Reporting Requirements
Reservoir, tailrace, and spill channel sampling activities began in July 2018 to establish
pre -construction conditions. Sampling will continue throughout the duration of the
project, which is anticipated to be completed by March 2021. Duke Energy will consult
with applicable state and federal regulatory agencies to determine if potential
remediation measures should be implemented based on water quality monitoring results
during construction.
' The sediment berm will be constructed immediately prior to excavation and will not be in -place during
the pre -construction phase.
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Proposed Duke Energy Monitoring Plan
References
Bosch, J. and R.U. Meckenstock. 2012. Rates and potential mechanism of anaerobic
nitrate -dependent microbial pyrite oxidation. Biochemical Society Transactions
Volume 40, part 6.
DeNicola, D.M. and M.G. Stapleton. 2016. Using Macroin vertebrates to assess
ecological integrity of streams remediated for acid mine drainage. Restoration
Ecology 24:5, 656-667.
Gray, N.F.and E.Delaney. 2008. Comparison of benthic macroin vertebrate indices for
the assessment of the impact of acid mine drainage on an Irish river below an
abandoned Cu-S mine. Environ Pollut. 155:1, 31-40.
He, F., W.Jiang, T.Tang and Q.Cai. 2015. Assessing impact of acid mine drainage on
benthic macroinvertebrates: can functional diversity metrics be used as
indicators?. Journal of Freshwater Ecology, 30:4, 513-524.
HDR. 2017. Geological and Geotechnical Subsurface Investigation, East Fork Hydroelectric
Project and Cedar Cliff Development (FERC No. 2698). Tuckasegee, North
Carolina, Report for Duke Energy of the Carolinas, LLC.
HDR. 2018a. Cedar Cliff Rock Spoil Evaluation. East Fork Hydroelectric Project
and Cedar Cliff Development (FERC No. 2698) Tuckasegee, North Carolina
HDR. 2018b. Cedar Cliff Hydroelectric Development Auxiliary Spillway Upgrade Project
Status Update and Permitting Process. Power Point Presentation for Agency
Briefing January 18, 2018
Nantahala Power and Light. 2000. FERC Relicensing First Stage Consultation Package.
East Fork Hydroelectric Project, FERC Project No. 2608-NC
North Carolina Division of Water Quality. 2011. Basin -wide Assessment Report Little
Tennessee River Basin. Water Quality Section, Division of Water Quality, North
Carolina Department of Environment and Natural Resources. Raleigh, NC.
Pugh, C.E., L.R. Hossner, and J.B. Dixon. 1984. Oxidation rate of iron sulfides as affected by
surface area, morphology, oxygen concentration, and autotrophic bacteria. Soil
Science. 137:5, pp. 309-314.
Stumm, W. and J.J. Morgan. 1981. Aquatic Chemistry. John Wiley & Sons, Inc.,New York,
NY, 780p.
Svitok, M., M. Novikmec, P. Bitusik, B.Masa, J. Obona, M.Ocadlik 5 and E.Michalkova.
2014. Benthic Communities of Low -Order Streams Affected by Acid Mine
Drainages: A Case Study from Central Europe. Water 6,1312-1338.
Page 8 of 8
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