20030181 Ver 7_More Info Received_20100528

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Carolinas
May 27, 2010
Mr. John Dorney
North Carolina Division of Water Quality
2321 Crabtree Boulevard, Suite 250
Raleigh, NC 27604
Re: Submittal of Section 401 Water Quality Certification Addendum No. 3
Mission Hydroelectric Project, FERC No. 2619
DWQ #0;--ewe- 0 3_ m I S I v -1
Clay and Cherokee Counties, North Carolina
Dear Mr. Dorney:
HYDRO LICENSING AND LAKE SERVICES
Duke Enerp Carolinot, LLC
526 South Church St.
Charlotte, NC 28202
Mailing Address:
ECI2K / PO Box 1006
Charlotte, NC 28201-1006
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WETLANDS AND 6TORL"ia`ER QRAPICFi
This Addendum No. 3 replaces Addendum No. 2 dated May 26, 2010 that Duke filed with your
office. Please disregard Addendum No. 2.
On June 16, 2009, Duke Energy Carolinas, LLC (Duke) withdrew the previous Mission Project
401 Water Quality Certification (401 WQC) Application and simultaneously submitted a new
401 WQC Application to the North Carolina Division of Water Quality (NCDWQ). The one-
year timeframe that the Federal Energy Regulatory Commission (FERC) allows states to process
401 WQC applications for relicensing of hydro projects expires on June 16, 2010 (i.e., one year
following the date that Duke's 401 WQC Application was stamped accepted by NCDWQ) for
the Mission Project.
As you are aware, Duke has been engaged in consultation with the United States Fish & Wildlife
Service (USFWS), NCDWQ, North Carolina Division of Water Resources (NCDWR) and the
North Carolina Wildlife Resources Commission (NCWRC) to prepare a Lake Level and Flow
Management Plan, a Maintenance and Emergency Protocol and a Sediment Study Plan to help
further define how the hydro project could operate under a New License from the FERC. This
consultation has been productive and Duke is very grateful for the time commitment provided by
these agencies over the past several weeks.
www.duke-energy.com
Mr. John Dorney
May 27, 2010
Page 2
Under separate cover dated May 26, 2010, Duke filed the Mission Project Lake Level and Flow
Management Plan along with the Nantahala Area Run-of-River Projects Maintenance and
Emergency Protocol (as an Appendix to the Mission Project Lake Level and Flow Management
Plan) as Addendum No. 1 to its Mission Project 401 WQC Application. The agency consultation
noted above appears to have resolved the issues relative to the documents provided in Addendum
No. 1.
Attached to this letter you will find Duke's proposed Sediment Study Plan. Duke has
incorporated most of the agency comments into this Sediment Study Plan and we are hereby
submitting the Plan as Addendum No. 3 to Duke's Mission Project 401 WQC Application.
Duke also offers the following excerpts from an important document produced by the FERC as
information for the record that may be useful and relevant to NCDWQ's decision-making
process:
In the Environmental Assessment (issued in July 2006) the FERC states:
Based on our analysis of sediment issues discussed above for the Franklin and Mission
Projects, staff concludes that the Community Stakeholders recommendations concerning
reservoir sediments and their removal, would be addressed in the development, for
Commission approval, of a generic, long-term sediment management plan developed for
the Franklin and Mission Projects after the sediment removal and drawdown study was
completed for one of the four target projects (i. e., Mission, Franklin, Dillsboro, or
Bryson). (p. 66, FERC Final Environmental Assessment, Nantahala West Projects, July
2006)
Further, the FERC's analysis of this issue states:
Turbidity in the river downstream of the dam would likely increase during drawdown and
sediment removal operations. The effects on water quality would likely be minimal
because (1) these maintenance operations occur infrequently (once every 7 to 8 years as
estimated by Duke) and for short duration (2 to 3 days), (2) both reservoirs {Franklin and
Mission Project reservoirs) are full of sediment and have no effective sediment trapping
function, so high turbidity during storm events is a normal occurrence in both rivers (as
is the case in most unregulated rivers in this part of North Carolina), and (3) the
turbidity in the river during sediment removal is likely to be similar to the turbidity that
would occur naturally during several storm events over the 7- to 8 -year period.
Mr. John Dorney
May 27, 2010
Page 3
Furthermore, sediment quality would not be a problem for these projects because(]) the
watersheds are largely undeveloped and have no known sources of major organic or
inorganic contaminants; (2) sediment quality data from the Dillsboro Project (which has
a more-developed watershed) does not show any chemical contamination of concern
(FWS, 2004); and (3) both reservoirs are full of sediment, so what is trapped behind the
dam is no different from what passes through the reservoir during every storm event. (p.
67, FERC Final Environmental Assessment, Nantahala West Projects, July 2006)
The Franklin and Mission projects operate in ROR mode and therefore have little effect
on water quality. However, there were concerns about potential water quality issues at
these two projects related to occasional emergency shutdowns, maintenance activities,
and sediment removal efforts. The installation of new reservoir monitoring equipment
(PLCs) would provide better controls for reservoir water levels, and the development of a
Lake Level and Flow Monitoring Plan would ensures flows are provided downstream
during any emergency shutdowns The specification of minimum flows below both project
dams during reservoir drawdown and refill, and the development of long-term, sediment
management plans would provide safeguards to ensure site-specific water quality
standards would be preserved and thus, reduce any cumulative adverse effects on water
quality associated with all three projects. (p. 71, FERC Final Environmental Assessment,
Nantahala West Projects, July 2006)
FERC concurred with Duke's proposal to develop of a Long-Term Sediment Management Plan.
The Sediment Study Plan that Duke proposes is a precursor for a Long-Term Sediment
Management Plan. Duke believes that this study needs to be completed and the results
appropriately considered before a Long-Term Sediment Management Plan can be developed.
If there are any questions please call Steve Johnson at 704-382-4240.
Sincerely,
0,7
Steven D. Jester, Vice President
Hydro Strategy, Licensing and Lake Services
Duke Energy Carolinas, LLC
Attachment
cc: Mr. Kevin Barnett, Asheville NCDWQ Regional office
Mr. John Dorney
May 27, 2010
Page 4
Mr. Jim Mead, NCDWR
Mr. Chris Goudreau, NCWRC
Mr. Mark Cantrell, USFWS-Asheville
Secretary, FERC
Steve Johnson, Duke
Jeff Lineberger, Duke
Phil Fragapane, Duke
Duke Energy Carolinas, LLC
Nantahala Area Run-of-River Projects
Sediment Study Plan
May 27, 2010
In order to address concerns related to potential sediment releases that may be caused by hydro project operation
and maintenance, Duke Energy Carolinas, LLC's (Duke) License Applications for the Nantahala Area Run-of-
River (ROR) Projects (Projects) (i.e., the Mission, Bryson and Franklin Projects) proposed the development of a
Long-Term Sediment Management Plan. The FERC concurred with this recommendation (i.e., Nantahala West
Project Final Environmental Assessment-July 12, 2006) and stated its expectation that Duke consult with the
appropriate resource agencies to develop a Long-Term Sediment Management Plan for the ROR Projects, as well
as specific Lake Level and Flow Management Plans (under a separate cover).
Purpose
The purpose of the Nantahala Area ROR Projects Sediment Study Plan is to provide a framework and guidelines
for appropriate management of sediment and monitoring of sediment releases associated with normal maintenance
and emergency activities. This study plan will provide the basis for a Long-Term Sediment Management Plan
that will be developed after completion of this Sediment Study in consultation with the resource agencies.
Objectives
The objectives of the Sediment Study Plan for the ROR Projects are as follows:
1. Describe sediment study procedures during the first normal sediment maintenance operation at one of
the Nantahala Area ROR Projects.
2. Provide information to allow the Licensee to develop a Long-Term Sediment Management Plan
Sediment Management
The proposed Sediment Study for the Nantahala Area ROR Projects (i.e., Mission, Bryson, and Franklin Projects)
is based upon a pragmatic approach incorporating general knowledge of sediment behavior but flexible enough to
incorporate existing or future knowledge of sediment transport and any subsequent impact to downstream aquatic
life including listed species and important or designated critical habitats. The basic approach for either limited
sediment removal operations or reservoir drawdown involves four steps, namely: (1) planning, (2) consultation,
(3) monitoring, and (4) documentation.
The first step in the development of a Long-Term Sediment Management Plan is to identify, through this initial
pilot study, the appropriate protocols and evaluation of acceptable boundaries of sediment loading due to limited
sediment removal (i.e., intake zone) and/or reservoir drawdown. After gathering this initial information, the
second step of this process is to incorporate this information into a Long-Term Sediment Management Plan which
will guide the planning, consultation, monitoring, and documentation of future sediment removal or drawdown
activities.
Sediment Removal Pilot Study
This study would be conducted on the first sediment removal operation at the Franklin, Bryson, or Mission
Projects following the submittal of this Sediment Study Plan to the North Carolina Division of Water Quality
(NCDWQ) as an addendum (Addendum No. 3) to Duke's Application for 401 Water Quality Certification (401
WQC) for each Nantahala Area ROR Project filed with NCDWQ in June, 2009. Since many aspects of the
geography, geology and river conditions are similar between the ROR Projects, the results of this pilot study may
provide the basis for future limited sediment removal activities for the other ROR Projects in the Nantahala Area.
Limited sediment removal in the immediate vicinity of the intake areas (i.e., forebay) of the powerhouses
typically involves removing accumulated debris and sediment from the reservoir via a mechanical bucket and
barge method. In the past, up to approximately 6,000 cubic yards of sediment have been removed at one time
from the individual ROR Project forebay areas. However, even though most of the material is removed, some
fine-grained sediments such as silts are re-suspended in the water column during the process and moved
downstream. Since the Licensee typically does not operate the generating units during sediment removal
operations, the re-suspended sediments would move downstream by spilling over the dam or, if necessary,
through the Tainter gates.
The process for the initial Sediment Removal Pilot Study will be as follows:
Establish Methodolo2v and Assessment for Limited Sediment Removal Operation
1. Limited Sediment Removal
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a. Operations would be planned during periods with Project inflows that are equaled or exceeded
25% to 50% of the time.
b. Operations would be conducted at drawdowns of approximately 3 feet below the Normal Target
Elevation and under the notification and consultation requirements as described in the Nantahala
Area ROR Projects Maintenance and Emergency Protocol (which is an Appendix to this
document and which has already been filed with NCDWQ as an Appendix to Addendum No. 1
to Duke's 401 WQC Application. To avoid confusion, Duke is not including this Appendix
again in this filing of Addendum No. 3).
2. Forebay Assessment
a. Volume of Sediment Removed
i. Perform a depth survey in the immediate intake area prior to sediment removal and
estimate the total volume of material to be removed
ii. Utilize the same methodology to perform a depth survey in the immediate intake area
after sediment removal to estimate the total volume of material that was removed
b. Develop Protocol for Measurement of Sediment
i. Prior to sediment removal
1. Sample (i.e., gradation) the sediments to be removed and estimate the potential
for re-suspension
2. Establish relationship between turbidity (field estimate of suspended solids) to
wet weight and dry weight of sediment remaining in suspension
ii. During Limited Sediment Removal
1. Sample (i.e., gradation) the suspended sediments transported into the reservoir
during limited sediment removal
2. Sample (i.e., gradation) the suspended sediments transported from the reservoir
during limited sediment removal. Sediment removal will cease temporarily when
downstream turbidity is greater than 50 NTU above ambient. Sediment removal
will restart when downstream turbidity measurements are 25% or less above
ambient turbidity.
3. Establish relationship between turbidity (field estimate of suspended solids) to
wet weight and dry weight of sediment from sediment samples
iii. Develop Protocol for Measurement of Total Sediments Transported from Reservoir Due
to Sediment Removal
1. Measure (calculate) spill flow
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2. Calculate total sediments transported into the reservoir (mass per day, mass total)
3. Calculate total sediments transported from the reservoir (mass per day, mass
total)
3. River Assessment
a. Establish monitoring stations at `sensitive' sites (sites either of biological interest including the
known listed species communities and critical habitats and/or those considered prone to
deposition such as shoals) in consultation with federal and state agencies
i. Sample water for suspended sediments (able to calculate mass per day, mass total)
ii. Pre and post sediment removal operations, sample substrate for deposition
b. Document deposition areas and particle size distribution through bedload sampling and
photography.
4. Report
a. Document the methods, results, conclusions and recommendations of the reservoir and river
assessment and provide to the pertinent agencies (i.e., Federal Energy Regulatory Commission
(FERC), United States Fish and Wildlife Service (USFWS), North Carolina Division of Water
Resources (NCDWR), North Carolina Division of Water Quality (NCDWQ), and North Carolina
Wildlife Resources Commission (NCWRC) for review).
b. The results, conclusions and recommendations will provide the bases for the future Long-Term
Sediment Management Plan.
Long-Term Sediment Management Plan Development
Based upon results of the Sediment Removal Pilot Study, Duke will prepare a Long-Term Sediment Management
Plan to guide future sediment removal operations at the Nantahala Area ROR Projects. The Long-Term Sediment
Management Plan will include a maintenance drawdown and refill protocol that minimizes flow fluctuations and
reservoir sediment mobilization by addressing rates of drawdown and refill (to coincide with precipitation events
and rising hydrograph) and scheduling drawdowns to coincide with season of least potential for harm to
downstream aquatic communities, whenever possible. In addition to the specific elements provided by the
Sediment Removal Pilot Study, the Long-Term Sediment Management Plan will also include several basic
elements, including the following:
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1) Short-Term Sediment Monitoring Study:
Once the FERC has issued the Subsequent License for the Franklin Project, Duke has fully implemented the
Lake Level and Flow Management Plan at the Franklin Project and the two hydro units at the Franklin Project
are fully restored to operational status, Duke will implement a short-term turbidity and/or suspended solids
monitoring study at the Franklin Project for a period of two years. The monitoring will cover a range of
operating conditions and river flows and will be used in the development of the Long-Term Sediment
Management Plan for the Nantahala Area Run-of-River Hydro Projects. In order to conduct this study, Duke
will utilize measurements that are already being provided by USGS at the existing Cartoogechaye Creek gage
to develop a measurement of turbidity and/or suspended solids in inflows to the Franklin Project. For
measurements downstream of the Franklin Project, Duke will contract with the USGS to include turbidity
and/or suspended solids monitoring at the USGS gage at the Iotla Bridge (i.e., the USGS streamflow gage that
Duke is proposing to reactivate for a 10-year period per the Franklin Project Lake Level and Flow
Management Plan) for a period of two years. After this two-year monitoring period, Duke will prepare a
report summarizing the information and consult with the USFWS, NCWRC, NCDWQ, and NCDWR on
study results.
2) Trash and Debris Management:
The Licensee will remove man-made trash from the intake racks and properly dispose of the trash in
accordance with the Project's proposed trash removal plan.
3) Sediment Management Plan Components:
The Long-Term Sediment Management Plan will incorporate trash rack maintenance guidelines,
debris/sediment management and removal, and guidelines for emergency drawdown including
drawdown procedures, timing, rates of drawdown and refilling, and agency notification. The
Licensee will conduct a post-relicensing study to determine what the adequate instream flows are if
the September median flows cannot be met during those very infrequent periods.
4) Notification and Consultation
The proposed Long-Term Sediment Management Plan will be prepared in consultation with the pertinent
federal and state agencies (i.e., FERC, USFWS, NCDWR, NCDWQ, and NCWRC). Communication with
resource and regulatory agencies about maintenance and emergency operations at the ROR Projects is a
critical component of protecting the environmental resources downstream of these facilities. The Nantahala
Area ROR Projects Maintenance and Emergency Protocol (MEP) is included as the Appendix to this
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document and covers the appropriate notifications and consultations required when a ROR Project reservoir
must be drawn down or sediment removal is required. The proposed Long-Term Sediment Management Plan
will also include the appropriate notifications and consultations.
5) Guidelines for Planned and Emergency Maintenance Operations
Following are the initial guidelines for conducting reservoir drawdowns or sediment removal operations:
a) As much as reasonably possible and except for emergency situations (see Appendix), the Licensee
will endeavor in good faith to conduct sediment releases only during periods of high flows, cold
temperatures, and low probability aquatic life spawning periods (e.g., spotfin chub spawning periods
from June through August).
b) Based on the Sediment Removal Pilot Study, site specific guidelines will be established for trashrack
maintenance, emergency drawdowns, Tainter gate operation, drawdown rates and refill, offsite
disposal, monitoring, and reporting during sediment removal operations.
6) Plan Adjustments
After five full calendar years of operations under the provisions of the Long-Term Sediment Management
Plan (i.e., after completion of the pilot study, the short-term sediment monitoring study and development and
FERC approval of the final Long-Term Sediment Management Plan), the Licensee will consult with the
agencies to review the implementation of the Plan and to determine if any Plan changes are needed and
agreeable to all the pertinent federal and state agencies and the Licensee. Any such meeting will be scheduled
and held no later than October 31 of the appropriate year.
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