NC0026051_Draft Permit_20220517

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DocuSign Envelope ID:745D34BB-6E8C-4E1B-AB4A-82C700FE8F20 _
,Mc 57ATE q.
ROY COOPER
Governor
ELIZABETH S.BISER ;.� n e
Secretory „` _.-
RICHARD E.ROGERS,JR. NORTH CAROLINA
Director Environmental Quality
May 12, 2022
Ms. Stephani e Bri xey
POTW Director/Deputy Director of Engineering
Triangle WWTP
5926 NC Highway 55 East
Durham, North Carolina 27713
Subject: Draft NPDES Permit Renewal
Permit NC0026051
Triangle WWTP
Durham County
Grade IV Biological WPCS
SIC Code 4952
Dear Ms. Brixey:
Enclosed with this letter is a copy of the Draft NPDES permit renewal for your facility. Rease
review this draft c aeful I y to ensure thorough understandi ng of the requirements and conditions it
contai ns. There are several changes from the ex sting permit, i nd udi ng the f of I owi ng:
• The system component l i st on the Supplement to Cover Shed has been revised based on
communication with fad lity staff.
• Based on your request and NPDES guidance regarding the reduction of monitoring
frequencies in NPDES permits for exceptionally performing facilities, monitoring
requirements for BOD5, Total Suspended Solids, Ammonia-Nitrogen and Fecal Col i form will
continue reduced at twice per week at both flow tiers[See A. (1.)].
• Based on the reasonable potential analysis (RPA) showing no reasonable potential to
violate state water quality standards, the monitoring requirement for Chloroform,
Bromodichloromethane, Dibromochloromethane, Total Copper and Total Zinc have been
removed from the permit [see A. (1.)].
• Based on the RPA showing no reasonable potential to violate state water quality standards,
but the maxi mum predicted value is > 50% of the al l owabl e concentration, limits for Total
Fluoride have been removed from the permit and monitoring has been reduced to quarterly
[see A. (1.)].
• Based on the RPA showing reasonable potential to violate state water quality standards
with a limited dataset (n < 8 samples) and two (2) values above the al l owabl e effluent
concentration, quarterly monitoring for B i s(2-ethyl hexyl) phthalate and Nitrate-Nitrogen
(NO3-N) have been added to the permit [see A. (1.)].
1
D_E Q 512 NorthNorth CarolinaSaisbury DepartmentStreet 1 of 1611 EnvironMaml entalService Quality I DI ivisionRalegh,No of WrthaterCaro Resourcesli Center na 27699-1611
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919.707 9000

DocuSign Envelope ID:745D34BB-6E8C-4E1B-AB4A-82C700FE8F20
• Based on Mercury TMDL evaluation showing no i ndi vi dual rect ll is exceeded the TB EL of
47 ng/L and no annual average exceeded the WQBEL of 12.0 ng/L, total mercury limits have
been removed from the permit.
• Based on Mercury TMDL evaluation showing mercury detectable val ues reported at l evel s
> 1 ng/L and since the permitted flow is greater than 2 MGD, a Mercury Minimization Rai
special condition has been added to the permit [ A. (1.) and A (11.)].
• The Division is implementing dissolved metals standards in all permits, per the 2016
revi si ons to State water quality standards. As such, the N PD ES Permitting Unit will need site-
sped f i c effluent hardncos data for each facility monitoring these metals in order to ca cul ate
permit limitations. Eff l uent hardnco has been added to the permit at a quarterly monitoring
frequency [See A. (1.)].
• Based on the Jordan Lake nutrient strategy (15A NCAC 02B .0270), nutrient allocations
are set among permitted dischargers; nutrient load allocations can be raised if a permitted
source connects to another permitted source, thereby recei vi ng that other source's al l ocati on
and thus rasing its limits. Since the Triangle WWTP is receiving additional load from non-
permi tted sources, the additional load must fit within the facility's allocations to meet
compliance. The al located nutrient loadswill bemaintaned in the permit [see A. (6.)].
• Based on minimum monitoring requirements for domestic wastewater faci l i ti es (15A
NCAC 02B .0508), instream (upstream and downstream) monitoring for Diswlved Oxygen,
Temperature, Fecal Col i form and Conductivity will be maintained in the permit, but reduced
to a monthly frequency [See A. (2.)].
• Based on the fad I i ty treating industrial wastewater, conductivity eff I uent monitoring has
been added to the permit
• Based on concerns over I oss of i nstream monitoring Efforts in tracking the progrcos of the
Jordan Lake nutrient strategy (15A NCAC 02B .0262), i nstream monitoring for Total
Phosphorus (TP), Orthophosphate (PO4), Total Kjeldahl Nitrogen (TKN), Nitrate + Nitrite
(NO3+NO2), and Ammonia-N (NH3-N) have been added to the permit at a monthly frequency
[See A. (2.)].
• Based on detecti ons of the emergi ng contami nait 1,4-D i oxane i n the waste stream at I evel s
< 10 µg/L from limited data(< 12 samples) in July-September 2019, monthly monitoring for
1,4-Di oxane has been added to the permit.
• A permit reopener speca condition has been added to modify 1,4-Dioxane monitoring,
treatment and/or compliance[see A. (11.)1.
• A special condition to monitor effluent PFAS chemicals 2/yea- has been added to the
permit, to be Effective six (6) months after EPA has a final wastewater method in 40 CFR136
method publ i shed i n the Federal Register.
• Some of the wording has changed in Special Condition A. (3.), Chronic Toxidty Permit
Limit, please revi eiv each paragraph careful I y.
• Spec al Condition A. (4.) has been modified to indude the specific three years in which
the Effluent Pollutant Scan shall be performed (2024, 2025, and 2026). In addition, at the end
of the Spec al Condition, 2' species Toxidty Testing Requirements for municipal pe-mi t
renewals per Federal Regulations[40 CFR 122.21(j)(5)] have been added.
• Federal regulations require electronic submittal of al discharge monitoring reports
(DM Rs)and program reports.The requi rement to continue reporti ng di scharge monitoring data
d ectroni cal l y using the NC D W R's Electronic Discharge Monitoring Report(eD M R) i nternet
application has been added to your N PD ES permit [See Special Condition A. (13.)].
North Carolina Department of Environmental Qua ity I Divis on of Wale Resources
D_E
Q�� 512 North Salisbury Street 11611 Mail Service Center I Raleigh,North Carolina 27699-1611
919.707.9000

DocuSign Envelope ID:745D34BB-6E8C-4E1B-AB4A-82C700FE8F20
• Parameter codes have been added to the Eff l uent Limitations and Monitoring
Requirements, I nstream Monitoring Requirements and Eff I uent Pol I utant Scan[See A. (1.), A.
(2.), and A. (4.)].
• Regulatory citations have been added to the permit.
• The map has been revised to show the i nstream monitoring"upstream" and "downstream"
l ocati ons in relation to the Outfal l.
hof The N PD ES standard conditions Parts I I, Ill, and IV)that are a part the permi t are not i nd uded
in this draft document (cover, map, and Pat I). The conditions are the sane as in your current
permit except that agency and division names have been updated. The latest version is avai I adl e at
https://bi t.l y/3k5N FaL and can be viewed online or downloaded as a PD F file.
Concurrent with this notification the Division is publishing a notice in a newspaper having
circulation in the general Durham County area, sol i d ti ng public comments on this draft permit.
Please provide any written comments you may have to the following: NCDEQ/DWR, NPDES
Permitting Branch, 1617 M a I Service Center, Raleigh, NC 27699-1617 no later than 30 days after
recept of this draft permit.
Fol I owi ng the 30-day public comment period, the Division wi II review al I pertinent comments and
take appropri ate acti on prior to i si 1i ng a final permit. If you have questions concerning this draft
permit, pl ease call meat [phone] or by email at [e-mail].
Si ncered y,
c-DocuSlgned by:
`-9FBBBC952DF8455.
Gay Pal mutter, Environmental Specialist II
NPDES Munidpal Permitting Unit
Hardcopy: NPDES Files
eCopy: US EPA Region 4
DWR/ Raleigh Regional Office/Water Quality/ Scott Vinson
DWR/ Operator Certification Program/ Maureen Kinney
DWR/ Ecosystems Branch/ Mark Vander Borgh
DWR/Aquatic Toxicology Branch/Zachary Thomas and Cindy Moore
DWR/ Munidpal Permitting Unit/ Pretreatment/ KeyesMcGee
DWR/ Public Water Supply/ Shawn Guyer
DWR/ Basin Raining Branch/ Nora Deemer
� North Carolina Department of Environrrk rta Qua ity I Diviaon of Wate Renrourc
NORTH caaa.i DE
Q�� 512 North Sa isbury Street 11611 Mal Service Ca to I Ra eigh,North Carolina 27699-1611
919.707.9000
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