NC0021024_Draft Permit Modification_20200922

ROY COOPER *I er:
Governor top k,
MICHAEL S.REGAN l
Secretary
S.DANIEL SMITH NORTH CAROLINA
Director Environmental Quality
September 22,2020
Mr. Thomas S. Warren,Assistant City Manager
City of Roxboro
PO Box 128
Roxboro,North Carolina 27573
Subject: Draft NPDES Permit Modification
Permit NC0021024
Roxboro WWTP
Person County
Grade IV WPCS
Dear Mr. Warren:
Enclosed with this letter is a copy of the draft NPDES permit modification for your facility. Please
review this draft carefully to ensure thorough understanding of the requirements and conditions it
contains. This draft modification contains the following change from your current permit:
• The Division has reviewed your request to modify the schedule of compliance for the new
ammonia limits. Special Condition A. (1)Effluent Limitations and Monitoring Requirements,
Footnotes 3 and 4 have been modified to reflect the adjusted schedule of compliance,with the
current limits expiring November 30, 2021 and the new limits becoming effective on
December 1, 2021.The City shall submit a status report within one year of the effective date
of this modification regarding the improvements made at the WWTP that were necessary for
meeting the new ammonia limits.The modified pages will become effective when the modified
permit is signed.
The NPDES standard conditions(Parts II,III,and IV)that are a part of the permit are not included
in this draft document (cover, map, and Part I). The conditions are the same as in your current
permit except that agency and division names have been updated. The latest version is available
at https://bit.ly/2BZ4xxx and can be viewed online or downloaded as a PDF file.
Concurrent with this notification the Division is publishing a notice in a newspaper having
circulation in the general Person County area, soliciting public comments on
this permit modification. Please provide any written comments you may have to the following:
NCDEQ/DWR,NPDES Permitting Branch, 1617 Mail Service Center, Raleigh,NC 27699-1617
no later than 30 days after receipt of this permit modification.
D_E
�.,- North Carolina Department of Environmental Quality I Division of Water Resources
�) 512 North Salisbury Street 11617 Mail Service Center I Raleigh.North Carolina 27699-1617
NORTH
+, wr� /.-" 919.707.9000

Following the 30-day public comment period,the Division will review all pertinent comments
and take appropriate action prior to issuing a final modified permit. If you have questions
concerning this draft permit modification, please call me at(919) 707-3613 or by email
at [e-mail].
Sincerely,
cety k,rtz.
Cassidy Kurtz,Engineer
NPDES Municipal Permitting Unit
Hardcopy: NPDES Files
Ecopy: US EPA Region 4
DWR/Aquatic Toxicology Branch
DWR/Raleigh Regional Office/Water Quality
DWR/Operator Certification Program/Maureen Kinney
LaBella Associates/Brian Houston
Page 2 of 2

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Permit NC0021024
2. The monthly average effluent BOD5 and TSS concentrations shall not exceed 15%of respective influent value
(i.e.,85%removal is required).
3. Limits expire on November 30,2021.
4. Limits become effective December 1,2021. After one year of data is collected under the new limits the permittee
may request a reduction in monitoring frequency.
5. The Division shall consider all effluent TRC values reported below 50 µg/L to be in compliance with the permit.
However,the permittee shall continue to record and submit all values reported by a North Carolina certified
laboratory(including field certified),even if these values fall below 50 µg/L.
6. Daily average dissolved oxygen effluent concentration shall not fall below 5.0 mg/L.
7. Chronic Toxicity(Ceriodaphnia)at 90%;quarterly during March,June,September,and December,[see A(2)].
8. Variable:instream samples shall be collected upstream and downstream 3/week during the summer months of
June,July,August,and September;and shall be collected weekly during the rest of the year.
9. The permittee shall perform three effluent pollutant scans during the term of this permit[see A(3)].
Effluent shall contain no floating solids or foam visible in other than trace amounts.
A.(2) CHRONIC TOXICITY PERMIT LIMIT(QUARTERLY) [15A NCAC 02B.0200]
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant mortality to
Ceriodaphnia dubia at an effluent concentration of 90%.
The permit holder shall perform at a minimum,quarterly monitoring using test procedures outlined in the"North
Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure,"Revised December 2010,or subsequent versions or
"North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" (Revised-December 2010)or subsequent
versions.The tests will be performed during the months of March,June,September,and December. These months
signify the first month of each three-month toxicity testing quarter assigned to the facility. Effluent sampling for this
testing must be obtained during representative effluent discharge and shall be performed at the NPDES permitted
final effluent discharge below all treatment processes.
If the test procedure performed as the first test of any single quarter results in a failure or ChV below the permit
limit,then multiple-concentration testing shall be performed at a minimum,in each of the two following months
as described in"North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure"(Revised-December
2010)or subsequent versions.
All toxicity testing results required as part of this permit condition will be entered on the Effluent Discharge
Monitoring Form(MR-1)for the months in which tests were performed,using the parameter code TGP3B for the
pass/fail results and THP3B for the Chronic Value. Additionally,DWR Form AT-3(original)is to be sent to the
following address:
Attention: North Carolina Division of Water Resources
Water Sciences Section/Aquatic Toxicology Branch
1621 Mail Service Center
Raleigh,NC 27699-1621
Completed Aquatic Toxicity Test Forms shall be filed with the Water Sciences Section no later than 30 days after the
end of the reporting period for which the report is made.
Test data shall be complete,accurate,include all supporting chemical/physical measurements and all
concentration/response data,and be certified by laboratory supervisor and ORC or approved designate signature.
Total residual chlorine of the effluent toxicity sample must be measured and reported if chlorine is employed for
disinfection of the waste stream.
DRAFT
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