NC0025305_Fact Sheet_20230830

DEQ/DWR
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES PERMIT NC0025305
Facility Information
Applicant/Facility
Name:
University of North Carolina at Chapel Hill/UNC Cogeneration
facility
Applicant Address:
302 South Building CB 9 1000; Chapel Hill, NC 27599-1000
Facility Address:
501 West Cameron Ave. CB 9 1855; Chapel Hill, NC 27599-1855
Permitted Flow
Outfall 001: 0.0922 MGD
Type of Waste:
100% industrial and stormwater
Facility/Permit Status:
Class I /Active; Renewal
County:
Orane County
Miscellaneous
Receiving Stream:
UT to Morgan
Creek
Stream
Classification:
WS IV, NSW
Subbasin:
03-06-06
Index No.
16-41-2-(5.5)
Drainage Area mil :
0.04
HUC:
03030002
Summer 7Q10 cfs
0
303 d Listed?
No
Winter 7Q10 (cfs):
0
Regional Office:
Raleigh
30Q2 (cfs)
0
State Grid / USGS
Quad:
D22NE
Chapel Hill, NC
Average Flow (cfs):
0
Permit Writer:
Sergei Chernikov,
Ph.D.
Date:
08/01/2023
Permit Writer:
Brianna Young
Outfall 001: Treated industrial wastewater
IWC %:
100%
Outfall 002: stormwater from east retention pond and accumulated sources
Outfall 003: stormwater from west retention pond and accumulated sources
BACKGROUND
The UNC-Chapel Hill Cogeneration Facility uses natural gas, coal, fuel oil, or other approved
alternative fuels to produce steam which is used for campus heating and to drive a turbine for
campus electricity. The treated industrial wastewater mixes with domestic wastewater, air wash
wastewater, cooling tower blowdown, and demineralizer wastewater which is sent to Orange
Water and Sewer Authority (OWASA) by contract. Sources of industrial wastewater include coal
pile runoff, stormwater from the fuel oil containment area, and low -volume process wastewater. If
OWASA contracted flow was exceeded, then on a short-term basis the Permittee could discharge
excess treated industrial wastewater through Outfall 001. The facility has not discharged any
wastewater through Outfall 001 since 2001.
An emergency once through/non-contact cooling water system that was never used is part of the
existing approved discharge to Outfall 001. This system has been removed.
Outfalls 002 & 003 are designated stormwater outfalls. Outfalls 001, 002, and 003 flows are
collected in a concrete vault and drain to an unnamed tributary into Morgan Creek, Cape Fear
River Basin.
As a combined NPDES permit for treated industrial wastewater and stormwater, Brianna Young
from the stormwater permitting unit coordinated and reviewed all permit details related to
stormwater. As such, questions related to stormwater should be directed to Brianna Young and/or
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the stormwater permitting unit. Preparing, formatting, and issuing of the combined permit narrative
and addressing the NPDES permit industrial requirements were coordinated by Sergei Chernikov,
Industrial NPDES permitting unit.
HISTORY
2006 — Issued current permit with new requirements for monitoring TKN and NOz + NOs, in
Outfall 001 pursuant to the Cape Fear River Basin permitting strategy. Provisional
narrative was added for Outfall 001 to cover emergency discharge of once through, non -
contact cooling water.
2011 — There was no discharge through Outfall 001 during this permit cycle. No data to review.
- The emergency piping configuration for once through cooling water was removed.
- New contract signed with OWASA to accept process wastewater more than permitted
flow.
- Bethany Georgoulias contacted the permittee on missing stormwater data and
documentation requirements for stormwater renewal. Follow up to clarify stormwater
sources previously undefined.
- Reviewed water balance and treatment operation with Permittee.
- Permit renewal was put on hold to allow RRO to investigate thallium issues at OWASA
that may be originating from this facility.
2023 - There was no discharge through Outfall 001 since April 3, 2001. No data to review.
INDUSTRIAL TREATMENT PROCESS
Miscellaneous industrial wastewater, coal pipe stormwater, fuel oil containment stormwater, and
process area stormwater are collected and sent to the industrial wastewater treatment facility. A
water/oil separator is used to capture any oil by-products before collecting the wastewater in the
two 63,000-gallon equalization basins. The wastewater then flows through a series of treatment
tanks for acid and caustic adjustment, followed by mixing with a polymer before discharging into
settling tanks. After settling in the tanks, the treated wastewater is intermittently discharged to the
local utility OWASA. If necessary, the treated wastewater can be diverted to Outfall 001.
STORMWATER CONTROL
There are two non -lined stormwater retention ponds on site. Stormwater can be either released
through an overflow or a manual drain value to Outfalls 002 & 003. The infiltration and
evaporation rates were sufficient to manage stormwater without any significant discharges.
Outfalls 002 & 003 also accumulate other local stormwater sources that may discharge.
SECTION A: INDUSTRAIL STRATEGY
Reasonable Potential Analysis (RPA)
There were no discharges during this permit cycle, so an RPA was not performed_ To ensure
correct monitoring and compliance for Outfall 001 parameters the measurement frequency was
defined as per discharge event per month.
Several technical corrections were made:
1. Whole Effluent Toxicity language was updated.
2. Electronic Reporting requirement was added.
SECTION B: STORMWATER STRATEGY (Contact: Brianna Y
Stormwater Permit History:
This facility has a combined NPDES wastewater and stormwater permit. Generally DWR has
been separating SW and WW permits more and more because of the increasing challenges and
complexities with keeping those together. However, because of the rare instances of wastewater
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discharge (emergency only) and stormwater retention pond discharges (large design and
infiltration capacity), the Stormwater Permitting Unit (SPU) worked with NPDES WW staff to
incorporate updated stormwater requirements in the combined NPDES permit.
The current Basinwide Plan (2005) highlighted the Local Watershed Plan for Morgan Creek
(http://www.nceep.net/services/lwps/Morgan_Creek/morgan.htm). UNC-Chapel Hill was a
participant in the Plan development. The Local Watershed Plan recommended restoration and
preservation projects through the implementation of 25 Best Management Practices to treat water
quality in 600 acres of priority sub -watersheds; 11 stream restoration projects to gain 28,000 linear
feet of restored stream; and 137 priority preservation parcels to protect over 600 acres of priority
habitat.
The 2005 Basinwide Plan recommendations included continued monitoring of Morgan Creek, and
for DWR to work with the Chapel Hill stormwater program to help identify stormwater retrofit
opportunities. The WARP project recommended retrofitting existing stormwater discharges and
preventing increased sedimentation to the watershed during future development.
There have been numerous changes to the structure of stormwater monitoring requirements since
the last permit issuance, including:
• Monitoring increased from semi-annually to quarterly for all parameters (qualitative and
quantitative)
• "No discharge" clarifications made
• Feasibility study requirement removed per updated stormwater program requirements
• eDMR requirement added
• Boilerplate language moved into body of the permit; boilerplate no longer attached
• Monitoring for O&G removed and monitoring for non -polar O&G is required
• Monitoring for total hardness added for outfalls where monitoring for hardness dependent
metals is required
• Benchmarks updated for parameters per guidance from DWR Standards group on
stormwater benchmarks
Stormwater Benchmarks and Tiered Response: Rather than limits, North Carolina NPDES
Stormwater permits contain benchmark concentrations. Stormwater benchmarks are numerical
action levels for stormwater monitoring. Benchmarks are not effluent limits, and benchmark
exceedances are not permit violations. Benchmarks provide facilities a tool for assessing the
significance of pollutants in stormwater discharges and the effectiveness of best management
practices (BMPs). Benchmark concentrations are intended as guidelines for the facility's
development and implementation of the Stormwater Pollution Prevention Plan (SWPPP).
Benchmark exceedances require the permittee to increase monitoring, increase management
actions, increase record keeping, and/or install stormwater BMPs in a tiered program. The permit
establishes a tiered approach to specify actions the permittee must take in response to analytical
results above benchmark concentrations. The tiered structure of the permit provides the permittee
and DEMLR wide flexibility to address issues that may arise with one or more parameters and/or
outfalls.
Metals benchmarks are calculated to mimic acute water quality standards and with the guidance
of DWR. NC DWR follows established federal procedures for calculating acute standards when
developing the benchmarks. Just like the acute standards, metals benchmarks normally reflect
one half of the calculated Final Acute Value (the "1/2 FAV" ). In most cases, translation into total
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recoverable values is based on an assumed hardness of 25 mg/L and a total suspended solids
(TSS) concentration of 10 mg/L. Acute standards protect aquatic life from negative impacts of
short-term exposure to higher levels of chemicals where the discharge enters a waterbody. The
Stormwater Permitting Program applies this approach because of the ephemeral nature of rainfall
events.
The Division may evaluate results to determine if a smaller suite of parameters for some outfalls
is adequate to characterize potential pollution or BMP effectiveness. For example, one or more
metals or other parameters may serve as an adequate tracer for the presence of ash pollution
during disturbance or ash removal in specific drainage areas at this site. For parameters that do
not have a stormwater benchmark, the Division may develop a benchmark value if appropriate
toxicity data become available or if rising trends in concentrations suggest a persistent source.
Stormwater Pollution Prevention Plan: The proposed permit conditions reflect the EPA and
NC's pollution prevention approach to stormwater permitting. The Division's maintains that
implementation of Best Management Practices (BMPs) and traditional stormwater management
practices that control the source of pollutants meets the definition of Best Available Technology
(BAT) and Best Conventional Pollutant Control Technology (BCT). The permit conditions are
not numeric effluent limitations but are designed to be flexible requirements for implementing
site -specific plans to minimize and control pollutants in stormwater discharges associated with
the industrial activity. Title 40 Code of Federal Regulations (CFR) § 122.44(k)(2) authorizes the
use of BMPs in lieu of numeric effluent limitations in NPDES permits when the agency finds
numeric effluent limitations to be infeasible. The agency may also impose BMP requirements
which are "reasonably necessary" to carry out the purposes of the Act under the authority of 40
CFR 122.44(k)(3). The conditions proposed in this draft permit are included under the authority
of both of these regulatory provisions. In essence, the pollution prevention and BMP
requirements operate as limitations on effluent discharges that reflect the application of
BAT/BCT.
Flexibility in Tier Responses: Tier Two actions provide an opportunity for the permittee to
propose an alternative monitoring plan for approval by the Region:
• Alternatively, in lieu of steps 2 and 3, the permittee may, after two consecutive
exceedances, exercise the option of contacting the DEMLR Regional Engineer as
provided below in Tier Three. The Regional Engineer may direct the response actions on
the part of the permittee as provided in Tier Three, including reduced or additional
sampling parameters or frequency.
• If pursuing the alternative above after two consecutive exceedances, the permittee may
propose an alternative monitoring plan for approval by the Regional Engineer.
The permit therefore allows the permittee to petition the Regional Office for monitoring changes
sooner than Tier Three (upon any four benchmark exceedances) and gives guidance on one
option to take. For example, the permittee may request that mercury only be monitored semi-
annually under the tiers, or that only parameters over the benchmark be monitored more
frequently. In this way, changes to the monitoring scheme for any outfall could be handled
outside of a permit modification.
NPDES DIVISION CONTACTS
If you have questions regarding any of the above information or on the attached permit, for
stormwater questions please contact Brianna Young at [phone] or email
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[e-mail], for industrial wastewater questions contact Sergei Chernikov at (919)
707-3606 or email [e-mail].
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