NC0048879_Comments_20230920

CARP
September 12, 2023
Mr. Nick Coco, P.E.
Department of Environmental Quality
Division of Water Resources
NPDES Municipal Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
RECEIVED
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NCDEQ/DWR/NPDES
Subject: North Cary WRF Draft NPDES Permit (NC0048879) Comments
Dear Mr. Coco:
On August 16, 2023, Cary received the draft NPDES permit for the North Cary Water Reclamation
Facility (NC0048879). We appreciate the opportunity to review the draft permit, fact sheet, and
associated reasonable potential analyses (RPA). Cary respectfully submits the following
comments and requests for modification of the proposed draft permit.
NPDES Permit Cover Letter
1. Total Residual Chlorine (TRC) limits and monitoring requirement (4th bullet point, pg. 1).
Request: Remove TRC monitoring as chlorine addition is not listed or permitted for effluent
disinfection. Cary will continue to maintain a redundant UV disinfection system, spare parts,
service support, and emergency backup generators for our existing and approved method
for effluent disinfection. If chlorine addition is required with a future permit modification,
chlorine monitoring language can be added.
2. Special condition to monitor effluent PFAS (6th bullet point, pg. 1).
Request 1: Cary requests NC Division of Water Resources (NCDWR) acknowledge the role
of the State of North Carolina approval processes for laboratory procedures prior to
requiring reporting of PFAS sampling results.
Request 2: Remove language requiring increased monitoring frequency of PFAS for
significant industrial users (SIU). This language is vague and unclear. Increased monitoring
for PFAS for SIU should be based on a legitimate concern supported by wastewater
monitoring data or categorical industrial user classifications that are found to manufacture or
discharge PFAS compounds at levels that warrant increased monitoring. It is anticipated
that virtually all industrial and domestic uncontrollable wastewater discharges will contain
some level of PFAS detections, therefore with this condition for any new SIU, would trigger
increased monitoring requirements with little or no justification or value in monitoring.
Part I, A.0.) Effluent Limitations and Monitoring Requirements (Pape 3 of 14)
1. Total Residual Chlorine (TRC) limits, monitoring requirement, and Footnote 5.

Request: Remove TRC monitoring requirements and footnote 5 as chlorine addition is not
listed or permitted for use in the effluent stream. If chlorine addition is required with future
permit modification, chlorine monitoring language can be added.
2. Footnote 3: "The monthly average effluent BOD5 and Total Suspended Solids
concentrations shall not exceed 15% of the respective influent value (85% removal)."
Request: Please correct the footnote to specify carbonaceous biochemical oxygen demand
(CBOD5) as permit limits specify CBOD5 not BOD5.
3. Footnote 4: "Twice per week sampling must occur on any two non-consecutive days
during the calendar week. "
Request: Please confirm that week's consisting of holidays will not require two non-
consecutive day sampling if holiday prevents it.
4. Effluent Pollutant Scan monitoring requirement.
Request: Add a footnote that confirms there is no requirement to monitor for TRC if chlorine
disinfection is not used.
Part I, A.(2.) Instream Monitoring Requirements (Page 5 of 14)
1. Table header language: "Beginning on the effective date of this permit and lasting until
lasting until permit expiration, the Permittee shall perform Instream sampling upstream
and downstream of Outfall 001 as specified below:"
Request: Remove duplicate language "lasting until."
2. Instream Monitoring Requirements table.
Request 1: Please add the Footnote 1 superscript to all monthly measurement frequencies
with exception to total hardness.
Request 2: Change the sample type for Total Nitrogen to "Calculated".
Request 3: Remove the sample location superscript "U10" for hardness — total as CaCO3
(mg/L)
3. Footnote 1 sentence: "Instream sampling requirements fGF are provisionally waived in
light of the permittee's participation in the Lower Neuse River Basins Association
(LNBA). "
Request: Remove the word "for" from the referenced sentence in Footnote 1.
Part I, A.M.) Additional Monitoring Requirements for Permit Renewal (Page 7 of 14)
1. (a) Effluent Pollutant Scans TRC monitoring requirement.
Request: Add language that confirms there is no requirement to monitor for Total Residual
Chlorine if Chlorine disinfection is not used.
CA Rv

Part I, A.(9.) PFAS Monitoring Requirement (Page 11 of 14)
Request 1: Cary requests NCDWR acknowledge the role of the State of North Carolina
approval processes for laboratory procedures prior to requiring reporting of PFAS sampling
results.
Request 2: Please remove language requiring increased monitoring frequency of PFAS for
significant industrial users (SIU). This language is vague and unclear. Increased monitoring
for PFAS for SIU should be based on a legitimate concern supported by wastewater
monitoring data or categorical industrial user classifications that are found to manufacture or
discharge PFAS compounds at levels that warrant increased monitoring. It is anticipated
that virtually all industrial and domestic uncontrollable wastewater discharges will contain
some level of PFAS detections, therefore with this condition for any new SIU, would trigger
increased monitoring requirements with little or no justification or value in monitoring.
Fact Sheet, 1. Basic Facility Information (Page 1 of 14)
Facility Information Table Treatment Units.
Request: Please change "aeration holding tanks" to "aerated holding tanks'.
Fact Sheet, 6. Water Quality -Based Effluent Limitations (WQBELs) — Ammonia and Total
Residual Chlorine Limitations (Page 6 of 14)
Description of any proposed changed to ammonia and/or TRC limits for this permit
renewal sentence: "However, in the event of an emergency where chlorination is required
as a backup or temporary means of disinfection at the facility, a TRC limit and monitoring
requirement have been added to the permit based on the review of the attached WLA
spreadsheet."
Comment: The NCWRF is not designed or approved to use chlorine for disinfection. Cary will
continue to maintain a dual -fully redundant ultra -violet (UV) disinfection system, spare parts,
service support, and emergency backup generators for our existing and approved method for
effluent disinfection. If chlorine addition is required with a future permit modification, chlorine
monitoring language can be added.
Fact Sheet, 6. Water Quality -Based Effluent Limitations (WQBELs) — Reasonable Potential
Analysis (RPA) for Toxicants (Page 6 of 14)
1. POTW Effluent Pollutant Scan Review.
Request: The fact sheet states, "Four effluent pollutant scans (2020, 2021 and 2022)...". Cary
requests that "four" be changed to "three" to match the number of scans performed and cited.
Fact Sheet, 6. Water Quality -Based Effluent Limitations (WQBELs) - Other TMDL/Nutrient
Management Strategy Considerations (Page 8 of 14)
1. Other TMDL/Nutrient Management Strategy Considerations.
UAW

Request: Please correct all typos to reflect the correct Total Nitrogen allocation of 143,246
Ibs/year.
Comment: Cary's North Cary WRF has a permitted total nitrogen load of 143,246
pounds/year and is based on our current 12.0 MGD capacity needs. Both the future hydraulic
capacity and nitrogen allocation is very important for Cary's future growth projections. The
North Cary WRF total nitrogen allocation is in accordance with the NC Neuse Nutrient Strategy
and the Neuse River Compliance Association co-permittee NPDES Permit NC000001. Cary's
total nitrogen allocation is finite and even with our WRF currently meeting and exceeding the
limits of technology for nitrogen removal, any reduction would be very detrimental. Any
proposed reduction in future hydraulic capacity, transportation factor calculation, or nitrogen
allocation is extremely important for Cary and likewise any point source discharger in the
Neuse River Basin subject to the Neuse Nutrient Strategy.
Fact Sheet, 12. Summary of Proposed Permitting Actions - Table 4 (Page 13 of 14)
1. Stream Sampling — Extreme Weather "Proposed Change" column
Request: The proposed change for Stream Sampling — Extreme Weather should be corrected
to read "Condition maintained; rearranged to Special Condition A.(8.)."
Thank you for the opportunity to review and provide comments on the North Cary WRF draft
NPDES permit renewal. If there are any questions regarding these comments, please feel free
to contact Mr. Jonathan Bulla, North Cary WRF Plant Manager at 919-677-0850
(jonathan.bulla(a�carync.gov).
Sincerely,
L I A�§
Jamie Revels, P.E.
Utilities Director
Cc: Jim Bridges, NCWRF Facilities Operation Supervisor, ORC
Donald Smith, Wastewater Collections Program Manager
Jonathan Bulla, NCWRF Manager
Corrie Bondar, P.E., Assistant Utilities Director
C" RY