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Home My WebLink About20030147 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