NC0085839_Correspondence_20230830

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Sibelco North America, Inc.
PO Box 588•Spruce Pine,NC 28777
(PHONE)828/765-1114
August 30, 2023
CERTIFIED MAIL
RETURN RECEIPT REQUESTED
Mr. Chris Johnson
Environmental Program Manager
Division of Water Resources, NCDEQ
1621 Mail Service Center
Raleigh,NC 27699-1621
Subject: Response to Notice of Violations
Sibelco North America, Inc.—Red Hill Facility
Red Hill,North Carolina,Mitchell County
Whole Effluent Toxicity(WET)Testing
Dear Mr. Johnson:
In response to the Notice of Violation(NC NOV-2023-TX-0032)dated August 8,2023 for failure of
Pass/Fail Chronic Whole Effluent Toxicity(WET)Testing for April 2023 and the subsequent Notice of
Violation (NC NOV-2023-TX-0038)date August 24,2023 for failure of the first follow-up multiple
concentration Chronic Whole Effluent Toxicity(WET)Testing for May 2023,please note the following.
After receiving the initial Pass/Fail failing results from our laboratory,Environmental Testing Solutions,
an immediate full investigation was undertaken to find the root cause of the failure. Multiple
concentration testing was completed the following month at varying effluent dilutions(0.825-13.2%)
while the investigation was underway. All areas of treatment were thoroughly reviewed and no issues
were discovered. After much discussion, it was determined that a change in the treatment system must
have occurred recently. The team suspected the issue possibly stemmed from changes to the polymer
system as this was the only recent modification.
In late February of this year,the anionic polymer batch pump malfunctioned and required replacement.
SNF, our polymer supplier installed a new batch system. SNF personnel also set the batch strength.
During our ongoing investigation, Sibelco requested SNF personnel return to evaluate the equipment and
batch strength. Upon review, SNF personnel discovered that the batch concentration was 9-10 times
higher than recommended for our treatment process. SNF personnel corrected the batch concentration and
we followed up very soon with multiple concentration toxicity testing. The results of toxicity testing were
well within our permissible limits.
As a result of these findings and to alleviate this issue, we had SNF personnel instruct our wastewater
operators on the proper process for setting polymer batch concentrations.
Sibelco strives to well exceed environmental regulations and are very proactive in maintaining
compliance at our facilities. We respectfully regret this occurred. We hope that requesting our supplier

Mr. Chris Johnson
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double checking their calculations and additional training for operators will help eliminate these
oversights in the future.
If you have any questions regarding this matter or require further information, please do not hesitate to
contact me at directly.
Regards,
Sandra Phillips ASustainabili
Fe son, P.E.Production Manager Manager North America
Red Hill,NC Spruce Pine,NC
sandra.phillips4isibelco.eom jeff.ferguson(a sibelco.com
828-688-9213 828-592-2764