HomeMy WebLinkAboutNCG500604_Denial_20200618ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. DANIEL SMITH
Director
To: Charles Weaver
NORTH CAROLINA
Environmental Quality
June 18, 2020
NPDES Compliance and Expedited Permitting
From: Hannah Headrick
Aquatic Toxicity Branch
Subject: Biocide Use Review
Messer
NPDES # NCG500604
Cabarrus County
Messer has requested approval of four chemicals: Nalco 1720, Nalco 3DT230, Nalco 9005, and
Stabrex ST70. These products will be discharged from its Outfall 001 and into an unnamed
tributary to Muddy Creek.
Calculations predict the use of Nalco 1720, Nalco 3DT230, Nalco 9005, and Stabrex ST70
products will cause toxic impacts to aquatic life in the receiving water body, an unnamed
tributary to Muddy Creek. Therefore, the use of these products as proposed at Messer is not
approved.
ATB has been in direct contact and corresponded with staff at Messer over months to modify this
proposal in ways that would allow for approval of these biocides. We asked that Messer explore
the possibility of demonstrating that the usage of the proposed biocides is directly related to
water quality parameters (pH and chlorine) specified in the facility's NPDES Permit that would
justify their usage at specified dosage rates. Messer contends that there is no way to demonstrate
in our worksheet nor calculations for the removal rates of the known constituents for aquatic
toxicity (mainly chlorine) via its proposed dechlorinator. ATB explained to Messer that since
our calculations framework is based on a model, it cannot take into account all possible
exceptions. ATB's biocide model continues to be used as a cost -saving measure to indicate
potential harm to surface waters when facilities discharge to surface waters. There are limitations
with this model and thus monitoring requirements maybe needed to ensure no potential harm to
the stream. One solution we proposed to Messer is that they could perform an annual full -
dilution test by an NC -Certified lab to verify that these four chemical additions in their waste
stream would not causing any potential problem(s).
Another option for Messer to obtain approval for use of these four products is to have a toxicity
testing requirement added to its NPDES Permit.
Please let us know if you have questions.
'OrKrm North Carolina Department of Environmental Quality I Division of Water Resources I Water Sciences Section
4401 and 4405 Reedy Creek Road 11621 Mail Service Center I Raleigh, North Carolina 27699-1621
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