NC0081931_correspondence_20150111

r21 ALCOA
January 05, 2016
NC Department of Environmental Quality
Division of Water Resources
Water Quality Permitting Section
1617 Mail Service Center
Raleigh, NC 27699-1617
Attention: Sergei Chernikov
Alcoa Inc.
APGI - Yadkin
Highway 740
PO Box 576
Badin, NC 28009
Certified Mail
RECEIVEDINCDEQIDWR
JAN 1,1 2015
Water Quality.
Permitting Section
Re.: Applicability of NPDES Permitting to Installation of Fixed Cone Valve DO
Enhancement Technology — High Rock and Tuckertown Dams
Dear Mr. Chernikov:
Alcoa Power Generating, Inc. (APGI) holds NPDES permits for wastewater discharges from the
High Rock (NC0081931) and Tuckertown (NC0081949) powerhouses. A 401 Water Quality
Certification was issued to APGI on October 23, 2015. Condition 12.C. of the 401 Water
Quality Certification pertains to the installation of fixed cone valves at High Rock and
Tuckertown Dams to improve the dissolved oxygen (DO) concentration in the tail waters. With
this letter, APGI is requesting a written concurrence from the Division of Water Resources that
NPDES permitting will not be required for the installation of the fixed cone valves.
At High Rock, fixed cone valves will be installed on two of the three scroll case valves for the
turbines. The water being discharged from the fixed cone valves will be water from the
upstream High Rock Reservoir. At Tuckertown, a single 24-inch diameter opening will be cored
through the dam to allow for the installation of an intake valve, associated piping, and one fixed
cone valve. The water being discharged from the fixed cone valve will be water from the
upstream Tuckertown Reservoir. No chemical treatment will be performed on the water that is
transferred but rather a physical aeration as the water leaves the cone valve to assist with
downstream dissolved oxygen levels.
In both situations, the water being discharged from the fixed cone valves does not meet the
definition of `waste' as defined in N.C.G.S. 143-213 (18). Furthermore, the fixed cone valves
are not `treatment works' as defined in N.C.G.S. 143-213 (17). Finally, the operation of the
fixed cone valves will not result in the discharge of stormwater. Therefore, we believe that none
of the criteria for permitting of point source discharges under 15A NCAC 2H .0100 apply and
that no NPDES permitting is required to enable the installation and operation of the fixed cone
valves at the High Rock and Tuckertown Dams.

Please provide us with a written concurrence regarding this applicability determination. If you
have any questions regarding this matter, please contact Henk van der Meyden at [phone]
or via e-mail at [e-mail].
Sincerely,
t.,-/L
Vice-Pres • nt
Manager, Hydro Operations
Cc. Paul Tran — APGI
Ray Barham - APGI