NC0003468_Approval_20220401

North Carolina Department of Environmental Quality | Division of Water Resources | Bio Lab
4401 Reedy Creek Road | 1621 Mail Service Center | Raleigh, North Carolina 27699-1621
919.743.8400

April 1, 2022

Terry Tuck
Duke Energy – Dan River Combined Cycle
(provided via email)

Subject: Biocide Use Review
Duke Energy – Dan River Combined Cycle
NPDES # NC0003468
Rockingham County

Dear Mr. Terry Tuck,

Duke Energy – Dan River Combined Cycle has requested approval of the below chemicals.
These products will be discharged from Outfall 001 and into the Dan River.

Product/Chemical Approval / Comment
60% Ferric Sulfate/Ferralyte 8130 PENDING – Awaiting further data
25% Sodium Hydroxide APPROVED
12.5% Sodium Hypochlorite APPROVED (TRC testing permit parameter)
NalClear 7768 APPROVED
3D Traser 3DT187 APPROVED
Nalco 3DT098 APPROVED
38% Sodium Bisulfite APPROVED
PERMATREAT PC-191T APPROVED
Avista Riocide IS2 APPROVED
19% Aqueous Ammonia APPROVED
Trisodium Phosphate APPROVED
Rhodamine WT Liquid Dye APPROVED
NALPREP IV APPROVED

DocuSign Envelope ID: 4BD3DEAD-7215-4534-8C9D-41FACB23015E

North Carolina Department of Environmental Quality | Division of Water Resources | Bio Lab
4401 Reedy Creek Road | 1621 Mail Service Center | Raleigh, North Carolina 27699-1621
919.743.8400

Calculations predict the use of the above products, at the stated dosage rate, will not cause toxic
impacts to aquatic life in the receiving stream, the Dan River. Therefore, the use of this product
as an additive to the cooling tower blowdown, non-contact cooling water, and occasional
draining from other operational systems at the Duke Energy – Dan River Combined Cycle is
acceptable.

If you have any questions or concerns, please contact Zach Thomas at [phone] or
[e-mail].

Sincerely,

Cindy Moore, Supervisor
Aquatic Toxicology Branch
Division of Water Resources, NCDEQ

Attachment: Biocide Spreadsheet
cc: Joyce Dishmon, Duke Energy (via email: [e-mail])
William Milam, Duke Energy (via email: [e-mail])
Gary Carroll, Duke Energy (via email: [e-mail])
Charles Weaver, DWR (via email: [e-mail])
Jenny Graznek, WSRO (via email: [e-mail])
ATB Electronic File & Laserfiche

DocuSign Envelope ID: 4BD3DEAD-7215-4534-8C9D-41FACB23015E