HomeMy WebLinkAbout20030147 Ver 2_More Info Received_20160811WATER STRATEGY, HYDRO
DUKE LICENSING AND LAKE SERVICES
ENERGY Duke Energy Corporation
526 South Church Street
PROGRESS Mail Code: EC12Y
Charlotte, NC 28202
August 10, 2016
The Honorable Kimberly D. Bose, Secretary
Federal Energy Regulatory Commission
888 First Street N.E.
Washington, DC 20426
Re: Duke Energy Progress, LLC
Yadkin -Pee Dee Hydroelectric Project No. 2206
Deviation from the Minimum Instantaneous Dissolved Oxygen Standard
Dear Secretary Bose:
Duke Energy Progress, LLC (Duke Energy) is required by Article 403 of the New License for
the Yadkin -Pee Dee Hydroelectric Project (Project) issued by the Federal Energy Regulatory
Commission (Commission) on April 1, 2015, to notify the Commission of planned and
unplanned deviations from License requirements no later than ten days after such an incident.
The 401 Water Quality Certification (WQC, Appendix A of the New License) also requires
Duke Energy to notify the North Carolina Division of Water Resources (DWR) within five days
of such an incident. Duke Energy is making this notification in response to a brief deviation
from the 4.0 mg/l minimum instantaneous water quality standard for dissolved oxygen (DO).
The United States Geological Survey (USGS) Gage No. 0212378405 (Pee Dee River at Highway
731 below Lake Tillery near Norwood, NC) records DO values in the tailrace of the Tillery
Hydro Station. During operations of the hydro generating units, a liquid oxygen injection system
is used to enhance DO concentrations in the Tillery forebay in order to comply with state DO
water quality standards (4.0 mg/L minimum instantaneous and 5.0 mg/l minimum daily average)
at the USGS Gage No. 0212378405. During periods of no generation, the Tillery Station utilizes
the crest gate (also referred to as the trash or sluice gate) to meet the minimum flow requirement
of the New License. This is a near -surface water release and is typically well oxygenated due to
its location in the reservoir.
For thirty minutes on Saturday August 6, 2016, the USGS Gage 0212378405 recorded DO
values of 3.9 mg/1, 3.6 mg/1, and 3.4 mg/l between 2300 and 2330 hours. These values were
recorded while the station was operating. Duke Energy believes these low DO values were a
result of a heavy rainfall/high inflow event in the upper portions of the Yadkin -Pee Dee River
Basin that resulted in a large quantity of poorly oxygenated water and introduced large quantities
of biological oxygen demanding material into the basin.
August 10, 2016
Kimberly D. Bose, Secretary
Page 2
The high inflow event on August 3rd was caused when the upper portion of the Yadkin -Pee Dee
River Basin received 11.89 inches of rain over approximately ten hours (measured at USGS Rain
Gage No. 362416080334345 at Ararat River at Ararat, NC). The Statesville, NC area received
8.48 inches of rain during the same time period (USGS Rain Gage No. 354822080521501).
These areas drain into the upper part of the Yadkin -Pee Dee River Basin and together they
resulted in very rapid runoff, predominately to High Rock Lake, which is operated by Alcoa
Power Generating, Inc. (APGI, See Figure 1: USGS 02116500 Yadkin River at Yadkin
College). On Thursday August 4, 2016, the APGI Project began operating continuously to
release the inflow, which resulted in an extended operating period for the Tillery Hydro Station
as well (see Figure 2).
At 2030 hours on Saturday August 6th, the operators of the Tillery Hydro Station (and the liquid
oxygen system) noticed the DO values recorded at USGS Gage No. 0212378405 began to
decrease from 5.2 mg/l to 5.0 mg/1. Despite more than doubling the amount of oxygen being
released into the reservoir, the DO values recorded at the gage continued to fall, reaching 4.1
mg/l by 2245 hours. At 2300 hours, the DO value recorded at USGS Gage No. 0212378405 was
3.9 mg/l and the decision was made to bring the generating units off-line and open the crest gate
to release the minimum flow. DO values of 3.6 mg/1 and 3.4 mg/1 were measured at 2315 and
2330 hours, respectively. The DO values increased from that point and remained above the state
standard. These values did not affect the daily average for August 6th as it remained above the
state standard at 5.7 mg/1.
To confirm the recorded values were not the result of inaccurate monitoring equipment, the
USGS was asked to visit the Tillery Station and confirm the monitoring equipment was working
properly. On Tuesday August 9th, USGS determined the DO monitor was reading within 0.04
mg/l of the calibrated field instrument which is within USGS acceptance criteria for continuous
DO monitoring instrumentation.
As stated above, the low DO values recorded at USGS Gage No. 0212378405 on August 6,
2016, were the result of the high inflow event and the large quantity of oxygen -poor water
resulting from the introduction of a large volume of oxygen demanding material in the reservoirs
over a short period of time. The drop in DO values was not a result of project operation, and
occurred in spite of our best efforts to prevent it. The operators and support staff responded in a
timely manner to increase the DO levels. These same actions by the staff have in the past
resulted in successfully maintaining DO levels above the state standards since the issuance of the
New License on April 1, 2015.
August 10, 2016
Kimberly D. Bose, Secretary
Page 3
Please contact Tami Styer at (704) 382-0293 (Tami.Styer@duke-energy.com) if you have
questions or require additional information.
Sincerely,
a�
Jeffrey G. Lineberger, P.E.
Director, Water Strategy and Hydro Licensing
Duke Energy
Enclosure: USGS Gage Data H Figures 1 and 2
cc w/enclosure: Ms. Karen Higgins, Division of Water Resources, 401Permitting Unit
North Carolina Department of Environmental Quality,
1617 Mail Service Center, Raleigh, NC 27699-1617
Mr. Fred Tarver - NCDWR
Mr. Corey Larsen - NCDWR
Tami Styer - Duke Energy
Jason Brown- Duke Energy
George Galleher- Duke Energy
Lynne Dunn- Duke Energy
Garry Rice- Duke Energy
Michel Brissie- Duke Energy
David Scott- Duke Energy
Shannon Todd- Duke Energy
Nob Zalme- Duke Energy
Figure 1: Discharge Graph for USES Gage No. 02116500 Yadkin River at Yadkin College
39999
CIL 19999
4J
d
w
USGS 02116500 YADKIN RIVER AT YADKIN COLLEGE, NC
Aug
Aug Aug Aug
Aug Aug
Aug
Aug
8182
93 94
95 96
97
99
2916
2916 2916 2916
2916 2@16
2916
2@16
---- Provisional Data Subject
to Revision ----
Median daily statistic [52 years]
— Discharge
_.
❑ Nz�
Aug
Aug Aug Aug
Aug Aug
Aug
Aug
8182
93 94
95 96
97
99
2916
2916 2916 2916
2916 2@16
2916
2@16
---- Provisional Data Subject
to Revision ----
Median daily statistic [52 years]
— Discharge
Figure 2: Discharge Data for USGS Gage No. 0212378405 at Tillery Hydro Station
USGS 0212378405 PEE DEE R AT HWY731 BL LK TILLERY NR NORWOOD, NC
29999
o
19999
CL _
4J
w
v
1999
t
0
499
99:99 12:99 99:99 12:99 99:99 12:99 99:99 12:99 99:99
Aug 94 Aug 94 Aug 95 Aug 95 Aug 96 Aug 96 Aug 97 Aug 97 Aug 9E
2916 2916 2916 2916 2916 2916 2916 2916 2916
---- Provisional Data Subject to Revision ----
i. Median daily statistic (2 years) — Discharge