20030147 Ver 2_More Info Received_20101223

?4*®r Progress Energy
Mr. John Dorney
North Carolina Division of Water Quality
401 Oversight/Express Review Permitting Unit
1650 Mail Service Center
Raleigh, NC 27699-1650
Dear Mr. Dorney:
December 21, 2010
na @ 1E OwL
DEC 2 3 2C.10
DENR - WATER QUALITY
%VIANDS AND STOW I.WATER BRANCH
SUBJECT: Request for Review of Installation of an Oxygen Diffuser System in Lake Tillery
at the Tillery Hydroelectric Plant Intake Area
Progress Energy is in the process of implementing modifications at the Yadkin-Pee Dee
Hydroelectric Project (Blewett Falls and Tillery Developments, FERC Project No. 2206),to
comply with North Carolina water quality standards for dissolved oxygen (DO) as required by
the 401 Water Quality Certificate issued by the North Carolina Division of Water Quality (NC
DWQ).' As part of its DO Enhancement Plan filed with the NC DWQ and Federal Energy
Regulatory Commission, Progress Energy has conducted a systematic evaluation of
technological measures since 2006 at each hydroelectric development to select the most
appropriate mechanism to comply with the DO standards. The 401 WQC requires that Progress
Energy comply with DO standards by the end of 2011.
Progress Energy has selected and installed a draft- tube; venting system at the Blewett Falls
Development to meet the DO standards. This''draft tube venting system was reviewed and
approved by the FERC during March 2010 prior to construction. Pilot tests of installed draft
tube vents on Units 3 and 4 during the summe_of 2010 indicated successful operation of the
system.2 We anticipate further trial testing oft is..system during 2011.
At the Tillery Development, Progress Energy has tested several different technologies to achieve
DO compliance, including passive aeration with draft tube venting, forced compressed air via
draft tube vents, compressed air bubbler systems, surface mixers, in-reservoir flexible weir
system, and in-reservoir oxygen diffuser system. As a result of these evaluations, Progress
Energy has selected an in-reservoir oxygen diffuser system coupled with passive aeration
through Units 1-3 six-inch draft tubes to enhance DO concentrations at the Tillery
Development.2
ILetter to Mr. Charles Gates, Progress Energy from Cyndi Karoly, N.C. Division of Water Quality. Re: Yadkin-Pee
Dee Project for Tillery and Blewett Falls Reservoirs, Rockingham, Stanly, Anson, Richmond, and Montgomery
Counties. DWQ #2003-0147, Version 2.0; Federal Energy Regulatory Commission Project Number 2206.
Approval of 401 Water Quality Certification-Modified. September 30, 2008.
2Progress Energy. 2010 (In press). Yadkin-Pee Dee Hydroelectric Project, FERC Project No. 2206, Raleigh, North
Carolina. Dissolved Oxygen Enhancement Field Verification Methods for the Tillery and Blewett Falls
Hydroelectric Developments. Phase IV-2010 Draft Tube Venting, Minimum Flow Tests, and Engineering
Evaluations.
Progress Energy Carolinas, Inc.
Tillery Hydro Plant
179 Tillery Dam Hoad 1
Mount Gilead, NC 27306
The in-reservoir oxygen diffuser system will be installed by Mobley Engineering, Inc., Norris,
Tennessee, and consists of a land-based liquid oxygen (LOX) facility and an in-reservoir diffuser
line array to introduce gaseous oxygen into the reservoir water column during the period of DO
stratification (typically May through late September or early October). The LOX facility will be
sited on the east shoreline of Lake Tillery within the FERC Project Boundary along a plant
access road previously developed (Figure 1). The LOX facility will be located just north of the
dam and intake area. The LOX facility will consist of two 15,000 gallon horizontal LOX tanks,
6 vaporizer towers (27 feet in height), 2 pressure vaporizers, and an oxygen-control skid for
system regulation (Figure 2). The maximum capacity of the facility will be 150 tons of
oxygen/day although average oxygen use is expected to be lower than this maximum capacity.
Regulation of oxygen use into the reservoir will be achieved via computer programming
synchronized with unit operation and flow rates. The construction area footprint will be
approximately 0.21 acres. Progress Energy and the oxygen vendor will maintain the LOX
facility. The LOX facility will be fenced with lighting and monitored via remote cameras. The
North Carolina State Historic Preservation Office (SHPO) has reviewed and approved the
proposed LOX facility construction area under Section 106 National Historic Preservation Act
consultation.3
Four oxygen distribution lines will route from the LOX facility down the east bank of the lake
and enter into the lake just upstream of the intake area (Figure 3). The distribution lines will be
placed in a protective piping sheath and installed above ground from the LOX facility into the
lake. There will be no ground disturbance of the routed distribution lines. The four distribution
lines will consist of a 4 inch buoyancy regulator line; a 3-inch oxygen distribution line; and 3
one-inch diffuser lines. The 4 inch buoyancy regulator line will allow for raising the submerged
distribution lines to the lake surface for any necessary maintenance via introduction of
compressed air. The distribution lines will extend approximately 3,500 feet upstream from the
intake and will be anchored in the submerged river channel, approximately 10 feet off the
reservoir bottom. Final placement of the oxygen distribution lines will be done with a GPS
depth recorder system. The oxygen distribution line field will be marked with warning buoys to
discourage anchoring by boaters who may be using the area. Boating navigation or recreational
use in Lake Tillery will not be affected by operation of the oxygen distribution lines. Progress
Energy will obtain the necessary 404/401 permits to install the in-reservoir diffuser system.
The oxygen distribution lines will deliver gaseous oxygen to maintain a target level of 5 mg/1 in
the reservoir water column at the intake area during the DO stratification period. The amount of
introduced oxygen will vary from year-to-year depending up the intensity of DO stratification
which is affected by reservoir inflow, climatological factors, and power plant generation levels.
The introduced oxygen will be entrained through the intake area and the power plant turbines
and draft tubes during generation periods and, subsequently, be introduced into the power plant
tailwaters to achieve DO water quality standard compliance downstream into the Pee Dee River.
The DO concentrations will be periodically monitored in the reservoir to determine if the 5 mg/1
target level is being met during the DO compliance period. Downstream, a permanent DO
3Letter to Mr. Ken Kennedy, Progress Energy Carolinas, Inc. from Mr. Peter Sandbeck, N.C. Department of Cultural
Resources, State Historic Preservation Office. Re: Construction of Liquid Oxygen Facility at the Tillery
Development, Yadkin-Pee Dee Hydroelectric Project, FERC 2206, Montgomery County, ER 10-21-32.
November 24, 2010.
2
compliance station will be installed and operated in the vicinity of the Highway 731 Bridge to
determine compliance with the state DO water quality standards. The proposed downstream
compliance monitoring station will be approved by the NC DWQ per 401 WQC stipulations!
The proposed operation of the oxygen distribution lines will enhance and provide additional
reservoir open water fish habitat for species such as striped bass, gizzard shad, threadfin shad,
and white perch during the summer months which would otherwise be unavailable during this
period. The potential for impingement and entrainment of fish is considered not to be significant
with seasonal system operation. During the relicensing Section 100) process, FERC concluded
and the U.S. Fish & Wildlife Service concurred that the bar width of the intake screens (2.6
inches) at the Tillery Plant was adequate for protecting fishery resources.4
Progress Energy requests that the North Carolina Division of Water Quality review and provide
comments on the proposed in-reservoir oxygen diffuser system. We anticipate construction of
the facility during the first part of 2011 with trial testing of the system during August-September.
Please call Larry Mann (919-546-5300) or John Crutchfield (919-546-2019) if you have any
questions about the proposed facility. We appreciate the cooperation of the NC DWQ in this
matter.
Sincerely yours,
en
Manager, Hydro Operations
Enclosures
c: Mr. Charles Wagner (FERC - Atlanta Regional Office)
Mr. Stephen Pawlowski (FERC - Washington, DC)
Mr. John Crutchfield
Mr. Larry Mann
Mr. Jim Mead
4Federal Energy Regulatory Commission. Letter to Mr. Pete Benjamin, Field Supervisor, U.S. Fish and Wildlife
Service from Mr. Mark A. Pawlowski, Chief, FERC Hydro East Branch 2. P-2197-073 and P-2206-030-NC.
Yadkin and Yadkin-Pee Dee River Hydroelectric Projects. Alcoa Power Generating Inc. and Progress Energy
Carolinas, Inc. Reference: Summary of 100) Teleconference. December 11, 2007.
3

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Yadkin-Pee Dee Hydroelectric Project No. 2206
Tillery Hydroelectric Development N LegendC progress Energy
A Proposed Area
Proposed Liquid Oxygen Facility
Figure 1. Location of proposed liquid oxygen facility at the Tillery Hydroelectric Development,
Yadkin-Pee Dee Hydroelectric Project FERC No. 2206.
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Figure 2. Preliminary engineering schematic layout of the liquid oxygen facility at the Tillery
Hydroelectric Development, Yadkin-Pee Dee Hydroelectric Project FERC No. 2206.
Figure 3. Proposed routing and layout of the in-reservoir oxygen diffuser line system to be
installed into Lake Tillery at the Tillery Hydroelectric Development, Yadkin-Pee Dee
Hydroelectric Project FERC No. 2206.
Lake Tillery Oxygen Diffusion System