NC0026689_Compliance Evaluation Inspection_20230328

� srgF
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA, GEORGIA 30303-8960
ELECTRONIC EMAIL
CONFIRMATION OF EMAIL RECEIPT REQUESTED
Troy B. Branch
Wastewater Treatment Plant ORC
P.O. Box 306
201 W. Salisbury Street
Denton, North Carolina 27239
[e-mail]
Re: Compliance Evaluation Inspection Report
NPDES Permit No. NCO026689
Denton Wastewater Treatment Plant
Dear Mr. Branch:
The U.S. Environmental Protection Agency Region 4 and the North Carolina Department of
Environmental Quality conducted a Compliance Evaluation Inspection on the Denton Wastewater
Treatment Plant on March 28, 2023. The objective of the inspection was to assess the Town's
compliance with the Clean Water Act and the National Pollutant Discharge Elimination System permit,
and to evaluate the general condition of the facility. The inspection results have been summarized in the
enclosed Compliance Evaluation Inspection Report.
The EPA appreciates the City's cooperation and courtesy. If you have specific questions about the
inspection report, please contact John C. Goodwin at [phone]. Please verify receipt of this letter
and report by email at the [e-mail].
Sincerely,
Digitally signed by Sayre,
Dennis Dennis
Sayre
� Date:2023.06.02
12:52:40-04'00'
(for)
Dennis Sayre, Acting Chief
Wastewater Enforcement Section
Water Enforcement Branch
Enclosure
cc: Jenny Graznak
North Carolina Department of Environmental Quality
Lon Snider
North Carolina Department of Environmental Quality
Internet Address (URL) http://www.epa.gov

United States Environmental Protection Agency Region 4
Enforcement and Compliance Assurance Division
Water Enforcement Branch
61 Forsyth Street, SW
Atlanta, Georgia 30303
m y
C Z
LIJ
�O 0
tiTq� pROTEG�C
Compliance Evaluation Inspection Report
Project No. CV-NC0026689 - 04282023
Denton Wastewater Treatment Plant
300 Council Access Road
Denton, North Carolina 27239
NPDES Permit Number: NC0026689
Date of Inspection: March 28, 2023

Title and Approval Sheet
Title: Compliance Evaluation Inspection Town of Denton, NC, Denton WWTP
Approving Official:
Digitally signed by Sayre,
Sa re, Dennis Dennis
y Date: 2023.06.02
12:08:02-04'00'
Dennis Sayre, Acting Chief
Wastewater Enforcement Section
Water Enforcement Branch
Inspector:
J O H N Digitally signed by JOHN
GOODWIN
Date: 203.06
GOODWIN 1114340 4-040'2
John C. Goodwin, Environmental Engineer
Wastewater Enforcement Section
Water Enforcement Branch

COMPLIANCE EVALUATION INSPECTION REPORT
Town of Denton WWTP, Project # CV- NCO026689 - 03282023
Contents
1. Introduction................................................................................................................................................1
2. Participants.................................................................................................................................................1
3. Facility Description....................................................................................................................................1
4. Inspection Procedures................................................................................................................................1
5. Findings & Conclusions.............................................................................................................................1
A. Permit Review...................................................................................................................................... 2
B. Records and Reports............................................................................................................................... 2
C. Flow Measurement................................................................................................................................. 2
D. Sampling................................................................................................................................................. 2
E. Site Visit (Operation and Maintenance)................................................................................................ 2
F. Sludge Handling..................................................................................................................................... 3
G. Effluent and Receiving Water................................................................................................................ 3
6. Discussion...................................................................................................................................................3

1. Introduction
On March 28, 2023, representatives of the United States Environmental Protection Agency Region
4 and the North Carolina Department of Environmental Quality (NCDEQ) conducted a
Compliance Evaluation Inspection (CEI) on the Denton Wastewater Treatment Plant (WWTP),
owned and operated by the Town of Denton (Town). The inspection was conducted under the
authority of Section 308 of the Clean Water Act (CWA), as amended. This report provides a
summary of the inspection.
2. Participants
Name Organization Email
John C. Goodwin EPA Region 4 Goodwin.John(q_)ena.gov
Troy B. Branch Town of Denton, Wastewater Treatment Plant ORC [e-mail]
Lon Snider NCDEQ Lon. Snidergncdenr.gov
Jenny Graznak NCDEQ Jenny. graznak(&ncdenr.gov
3. Facility Description
The WWTP is an activated sludge wastewater treatment plant that consists of bar screen
headworks, grit chamber, two oxidation ditches, four clarifiers, two aerated digesters, dual tertiary
filters, disinfection, and sludge drying beds. The facility is permitted to operate at 0.80 million
gallons per day (MGD), according to the Town's 2021 NPDES permit.
The headworks consists of three mechanical screens followed by manual grit removal, an influent
wet -well, and a lift station. The facility has dual oxidation ditches that lead to one of four clarifiers.
The facility maintains two center feed and two peripheral feed clarifiers for seperating return and
waste activated sludge. Tertiary sand filters are in parallel between the clarifiers and chlorination
chamber. The dual chlorination ditches are supplied by chlorine gas and sulfur dioxide gas for
dechlorination. Reuse water is currently only used internally within the WWTP.
4. Inspection Procedures
The overall objective of this CEI was to evaluate the condition and operational performance of the
WWTP and the Town's self -monitoring program and to offer compliance assistance as needed.
Specific tasks included conducting interviews with WWTP staff, reviewing Discharge Monitoring
Reports (DMRs) and other WWTP records, and conducting a site visit throughout the WWTP.
5. Findings & Conclusions
The Town has been in Significant Non -Compliance (SNC) for effluent limit exceedances of
dichlorobromomethane throughout the evaluation period from 07/01/2022 to 12/31/2021. The
facility has not been in Significant Non -Compliance but exceeded the limits for
dichlorobromoethane again from 04/01/2022 to 06/30/2022 and 10/01/2022 to 12/31/2023 The
WWTP was generally in good operational condition and appeared well maintained.

COMPLIANCE EVALUATION INSPECTION REPORT
Town of Denton WWTP, Project # CV- NCO026689 - 03282023
A. Permit Review
The Town's NPDES permit has an effective date of October 1, 2021, and an expiration date of
February 28, 2026. The WWTP is classified as a minor (less than 1.0 MGD discharger) and it is
currently limited in the NPDES permit to 0.80 MGD (Average Annual Daily Flow).
The facility's 2021 permit had no signature for the issuing representative from NCDEQ.
B. Records and Reports
EPA's Enforcement and Compliance History Online (ECHO) database shows the Town was in
Significant Noncompliance for exceeding NPDES effluent limits for dichlorobromomethane. The
Town also exceeded effluent limit for BOD in the first quarter of 2022 and flow exceedance once
in 2021.
No additional deficiencies were noted during the review of operator's logs, sampling analyses,
chain of custody sheets, and calibration logs.
C. Flow Measurement
Effluent flow is measured using a Honeywell digital ultrasonic meter. The flow records are
collected onto a circular chart flow recorder. The average flow is 470,000 gallons per day. The
flowmeters were last calibrated in February, 2023 by Wayne Henson. The digital flowmeter was
cycling a display of 0.189MGD during inspection.
D. Sampling
The composite samplers used for influent and effluent samples are collected for analysis by
Meritech. The influent sample volume was set to 120 mL but pulled a test sample size of 185mL.
This quantity would eventually result in overflow of the 2.5 gallon sample container. The sample
container was observed to have no lid during the inspection.
E. Site Visit (Operation and Maintenance)
The WWTP influent was observed to be purple. The cause is that the industrial user in their system
is a sock manufacturer and discharges dyes to the WWTP. Only one of the aeration ditches was in
operation since approximately 2001 according to the operator. It is currently used as overflow
during storm events. One of the center feed clarifiers was out of operation due to a rusted shaft.
The tertiary sand filters have been bypassed for approximately a year in an effort to isolate the
cause of the dichlorobromomethane effluent violations. The permitting authority appears to have
not been notified of any of the facility changes.
2

COMPLIANCE EVALUATION INSPECTION REPORT
Town of Denton WWTP, Project # CV- NCO026689 - 03282023
F. Sludge Handling
Waste sludge is collected in the Digester Tank. The Town no longer utilizes the drying beds for
sludge dewatering. The dried sludge from the digester tank is land applied approximately every
four years. The drying beds were observed to have sand media discarded from Denton's Water
Treatment Plant. This waste should be discarded appropriately from the site. If the facility chooses
to no longer use the drying beds then the facility should close the units and notify the permitting
authority.
G. Effluent and Receiving Water
The Town is permitted to discharge effluent from OutfalI D-001 to Lick Creek. The discharge
point was not accessible for inspection.
6. Discussion
The NCDEQ has inspected the facility annually for the past 5 years. The facility officials stated
that the source of the dichlorobromomethane was likely from the facility's chlorination chamber.
The chamber is constructed of cinder blocks. A pool coating was placed over the contact areas and
the baffles were replaced with stainless steel in an effort to reduce the dichlorobromomethane
amounts in 2022. There have been no SNC violations for dichlorobromomethane since the
modifications.
The EPA recommends the following:
• Ensure composite sampling containers are closed to prevent open venting of the samples
collected.
• Ensure composite sample pull volumes are accurate to the unit setting.
• Obtain a signed permit copy from NCDEQ.
• Notify NCDEQ for approval of any modifications of the permitted operations.
END OF REPORT
3