NC0026441_NOV-2020-PC-0328 Response_20200819

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Certified Mail # 70163560000044287298
Return Receipt Requested
July 29, 2020
Roy Lynch, Town Manager
Town of Siler City
PO Box 769
Siler City, NC 27344
SUBJECT: NOTICE OF VIOLATION & INTENT TO ASSESS CIVIL PENALTY
Tracking Number: NOV-2020-PC-0328
Permit No. NCO026441
Siler City WWTP
Chatham County
Dear Permittee:
The North Carolina Division of Water Resources conducted an inspection of the Siler City WWTP on June 3,
2020. This inspection was conducted to verify that the facility is operating in compliance with the conditions and
limitations specified in NPDES Permit No. NC0026441. A summary of the findings and comments noted
during the inspection are provided in the enclosed copy of the inspection report.
The Reconnaissance inspection was conducted by Division of Water Resources (DWR) staff from the Raleigh
Regional Office. The following violation(s) were noted during the inspection:
Inspection Area Description of Violation
Aerobic Digester Digesters A and B were almost full. The facility was using Equalization (EQ) Basins 3A
and 3B as digesters at the time of inspection, which were also full. The sludge thickening
basin had about two feet of space available. Sludge was being transferred from EQ
Basins 3A and 3B to the sludge thickening basin at the time of site visit.
Oxidation Ditches Mixed Liquor Suspended Solids (MLSS) were about 8000 mg/L., which is about 60% higher
than the targeted value (5000 mg/Q. Dissolved Oxygen (DO) was observed at 0.2, 0.5,
0.1, and 0.7 mg/L (from four locations in the oxidation ditches).
Operations & Maintenance Poor sludge management resulted in the inability to waste sludge as needed, which led to
upset conditions of the treatment plant indicated by elevated effluent Ammonia Nitrogen
and BOD.
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Inspection Area Description of Violation
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Secondary Clarifier The sludge blankets were high in both secondary clarifiers (Clarifier #1: 9 feet; Clarifier #2:
9.5 feet. Sidewall depth for both units is 14 feet).
The site inspection revealed the following violation of NPDES permit condition (NC0026441) which states the
following:
NPDES Permit N O026441 Part 11. Section C.2. Pro er 4 eration and Maintenance
Proper Operation and Maintenance
The Permittee shall at all times properly operate and maintain all facilities and systems of treatment and control
(and related appurtenances) which are installed or used by the Permittee to achieve compliance with the
conditions of this permit. Proper operation and maintenance also includes adequate laboratory controls and
appropriate quality assurance procedures. This provision requires the Permittee to install and operate backup or
auxiliary facilities only when necessary to achieve compliance with the conditions of the permit [40 CFR
122.41(e)).
In addition, the site visit conducted by DWR staff on July 20, 2020, revealed that the above
observed conditions at the facility were not improved significantly: all sludge digesters (including
EQ Basins 3A and 3B) and sludge thickening basin were full (no space for sludge wasting); MLSS
were still high (around 7000 mg/Q.
A Notice of Violation/Intent to Issue Civil Penalty is being issued for the noted violation of North Carolina General
Statute (G.S.) 143-215.1 and the facility's NPDES permit. Pursuant to G.S. 143-215.6A, a civil penalty of
not more than twenty-five thousand dollars ($25,000.00) may be assessed against any person who violates or
fails to act in accordance with the terms, conditions, or requirements of any permit issued pursuant to G.S.
143-215.1.
If you wish to provide additional information regarding the noted violation, request technical assistance, or discuss
overall compliance please respond in writing within ten (10) business days after receipt of this Notice. A review of
your response will be considered along with any additional information provided. You will then be notified of any
civil penalties that may be assessed regarding the violations. If no response is received in this Office
within the 10-day period, a civil penalty assessment may be prepared.
Remedial actions should have already been taken to correct this problem and prevent further occurrences in the
future. The Division of Water Resources may pursue enforcement action for this and any additional violations of
State law. If the violations are of a continuing nature, not related to operation and/or maintenance problems, and
you anticipate remedial construction activities, then you may wish to consider applying for a Special Order by
Consent.
Reminder: Pursuant to Permit Condition 6 in Section E. the Permittee is required to verbally notify the Regional
Office as soon as possible, not to exceed 24 hours, from first knowledge of any non-compliance at
the facility including limit violations, bypasses of, or failure of a treatment unit. A written report may
be required within 5 days if directed by Division staff. Prior notice should be given for anticipated or
potential problems due to planned maintenance activities, taking units off-line, etc.
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If you should have any questions, please do not hesitate to contact Cheng Zhang with the Water Quality
Regional Operations Section in the Raleigh Regional Office at 919-791-4200.
Sincerely,
DocuSigned by:
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Vanessa E. Manuel, Assistant Regional Supervisor
Water Quality Regional Operations Section
Raleigh Regional Office
Division of Water Resources, NCDEQ
ATTACHMENTS
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Public works and Utilities
August11,2020
Raleigh, NC 27699-161
ATTN: Vanessa E. Manuel, Assistant Regional Supervisor
Division of Water Quality
1617 Mail Service Center
Subject: NOTICE OF VOLATION
Tracking Number: NOV-2020-PC-0328
Permit No. NCO026441
Town of Siler City WWTP
Chatham County
Dear Vanessa E. Manuel,
DAUG 1 9 2020
DIVISION OF WATER RESOURCES
This letter is in response to the Notice of Violations issued on July 29, 2020 for the violations listed below.
• Aerobic Digesters — Digesters A/B were almost full. The facility was using Equalization (EQ) Basins 3A/3B
as Digesters at the time of inspection, which were also full. The sludge thickening basin had about two
feet of space available. Sludge was being transferred from EQ basins 3A/B to the sludge thickening basin
at the time of visit.
• Oxidation Ditches— Mixed Liquor Suspended Solids (MLSS) were about 8,000 mg/I, which is about 60%
higher than the targeted value (5,000 mg/I). Dissolved Oxygen (DO) was observed at 0.2, 0.5, 0.1, and 0.7
mg/I. (from the locations at the oxidation ditch)
• Operations & Maintenance — Poor sludge management resulted in the inability to waste sludge as
needed, which led to upset conditions of the treatment plant indicated by elevated Effluent Ammonia
Nitrogen and BOD.
• Secondary Clarifiers —The sludge blankets were high in both secondary clarifiers (Clarifier #1= 9' Clarifier
#2 = 9.5'. Sidewall depth for both units is 14'.
It is believed that these violations are a result of continuous unpredicted weather conditions that we have
been experiencing over the past few months. We have worked closely with Synagro to stay on top of our
Sludge Management, to include having a portable sludge press here earlier this year and having them
come more frequently. Due to the land conditions from the weather/wet season they have not been able
to come as frequently as we have needed. We are looking into potentially bringing in some dewatering
trailers to help us get ahead on sludge management. Synagro can bring a sludge press back however this
is very costly for the town. In addition to land applying sludge the dewatering trailers should allow us to
better manage sludge under our current conditions. In situations when our MLSS and sludge depths are

above average we must use available space our permit allows in order to properly manage the plant
process and incoming plant flow. At the time of the visit we were transferring sludge from the EQ basins 3
A/B to the Thickening Sludge Basin to make room to waste in result lowering our MLSS and sludge depths
in the Secondary Clarifiers. We have the ability to get supernatant from the Digesters A/B, EQ basins 3 A/B
and the thickening sludge basin, which we do often to allow us to waste. We added a new floating aerator
in Oxidation Ditch #1 to help with the DO issues. We are monitoring the DO's at the Oxidation ditches
closely. Every day we are taking (4) different reading (4) different times at (4) different locations in
addition to our regular monitoring processes. On 8/10/20201 purchased some inline DO meters that will
be tied into our SCADA system to better monitor DO in the Oxidation ditches. We have seen
improvements with the DO since adding the aerator. Also: we have not needed to turn blowers off at the
Oxidation Ditches or bypass the filters since 6/16/2020. We only turn blowers off at the Oxidation ditches
as a last resort and in the future, we will turn them back on every few hours as plant conditions allow us
to. The plant has been operating better the past month. We are seeing very little Ammonia and BOD is
under permitted limits as well.
If you have any questions, please do not hesitate to contact me.
Sincerely,
Brittany York — W WTP Superintendent
Town of Siler City WWTP
Cc: Roy Lynch Town Manager, Chris McCorquodale Public Works & Utility Director
Brittany York
W WTP Superintendent
PO Box 769.311 N Second Avenue
Siler City, NC 27344.0769
[e-mail]
Phone:[phone]
www.silercity.org
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