NCG500604_Messer LLC Midland Biocide Use Review Approval Letter_20211216

December 16, 2021

To: Patrick Carrube
Messer LLC – Midland
(via email: [e-mail])

From: Cindy Moore
Aquatic Toxicity Branch

Subject: Biocide Use Review
Messer LLC – Midland
NPDES # NCG500604
Cabarrus County

Messer LLC – Midland has requested approval of the chemicals, Nalco 3DT230, Nalco 7408,
Nalco 90005, Nalco STABREX ST70. These products will be discharged from Outfall 001 and
into a UT to Muddy Creek.

A chronic multi-dilution Ceriodaphnia toxicity test collected and performed 10/12/2021 by ETT
Environmental, Inc. produced a chronic value result of >100% and indicates the use of these
products, at the stated dosage rate, will not cause toxic impacts to aquatic life in the receiving
stream, Muddy Creek. Therefore, the use of these products as an additive to the cooling tower
blowdown, non-contact cooling water, and occasional draining from other operational systems at
Messer LLC - Midland 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

cc: Charles Weaver, DWR (via email: [e-mail])
Wes Bell, MRO (via email: [e-mail])
ATB Electronic File & Laserfiche
DocuSign Envelope ID: DE987B0A-2DC6-474D-8285-657B1D8B1C41