NC0003425_Correspondence_20200227

Responses to SELC comments for Roxboro Permit
02/27/2020
1. DEQ Must Protect Public Waters.
The heated discharge pond has been the integral part of the wastewater treatment system since
1966 and contains wastewater (primarily cooling water) generated by the plant. The USACOE
has conducted an inspection of the Roxboro facility and determined that Unnamed Tributary in
question is not waters of the US.
After the plant is retired and coal ash ponds and lagoons are permanently closed, the Division
will re-evaluate status of the streams on the site.
2. DEQ Must Strengthen the Pollution Limits in this Permit.
The need for water quality based effluent permit limits is determined based on the results of the
reasonable potential analysis (RPA). The RPA procedure utilized by the Division is conducted
in accordance with the EPA's regulation (40 CFR 122.44(d)(1)). When the permitting authority
determines, using procedures in paragraph (d)(1)(ii) of this section, that a discharge causes, has
the reasonable potential to cause, or contributes to an in -stream excursion above the allowable
ambient concentration of a State numeric criteria within a State water quality standard for an
individual pollutant, the permit must contain effluent limits for that pollutant. Permit limits are
added only if the results of the RPA indicate the potential for exceeding the water quality
standards, and are not arbitrarily assigned. However, absence of permit limits does not allow the
facility to violate instream water quality standards.
a. Outfall 003
The Technology Based Effluent Limits have been implemented at the internal outfalls in
accordance with the requirements of the 40 CFR 423. Applying these limits at the external
Outfall 003 will not make the permit more stringent due to the significant dilution from cooling
water that contains almost no pollutants.
The Division also conducted a Reasonable Potential Analysis for Outfall 003 based on the
assumption of ZERO dilution and determined that limits for pollutants of concern are not
required. Claim that the Division uses the entire lake for dilution is false.
The limit for Thallium was eliminated since the Division is using a new recommended Water
Quality Criteria for Thallium, the SELC has been provided a MEMO from the Standards Branch
that justifies the use of the new Criteria.
The language regarding the TRC is based on the limitations of the field instrumentation used to
measure the TRC and associated detection problems for measuring of the very low
concentrations of the Residual Chlorine in the effluent.
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The DEQ is unable to develop a limit for bromides due to the absence of the appropriate EPA
criteria and a paucity of the scientific research on the subject. The EPA is currently developing a
bromide criterion and when it is promulgated the DEQ will conduct the RPA analysis for the
facilities that discharge bromides. The appropriate limits will be subsequently implemented if
RPA indicates a need for such limits.
b. Outfall 001
Outfall 001 is a historic Outfall that has been omitted from the previous permit, in the Draft
permit the Division recognized the adjacent Unnamed Tributary and relocated Outfall 001
accordingly.
This Outfall is essential for excavation of the coal ash from the site and the Division applied
permit limits based on the assumption of the ZERO dilution.
The new Arsenic daily maximum limit is based on the new state water quality standard in
accordance with the most recent triannual review.
c. Outfall 002
The need for water quality based effluent permit limits is determined based on the results of the
reasonable potential analysis (RPA). The RPA procedure utilized by the Division is conducted
in accordance with the EPA's regulation (40 CFR 122.44(d)(1)). When the permitting authority
determines, using procedures in paragraph (d)(1)(ii) of this section, that a discharge causes, has
the reasonable potential to cause, or contributes to an in -stream excursion above the allowable
ambient concentration of a State numeric criteria within a State water quality standard for an
individual pollutant, the permit must contain effluent limits for that pollutant. Permit limits are
added only if the results of the RPA indicate the potential for exceeding the water quality
standards, and are not arbitrarily assigned. However, absence of permit limits does not allow the
facility to violate instream water quality standards.
Changes to the decanting/dewatering rates are based on the safety evaluation conducted by the
Dam Safety program. The RPA for decanting/dewatering is based on the new dewatering rate
and ZERO dilution assumption.
d. Outfall 006
This Outfall regulates discharge from the coal pile runoff that occurs as a result of the storm
events. These events are episodic and daily maximum limits are more appropriate tools to
regulate them. Monthly average limits for these discharges are meaningless since Outfall 006 has
no continuous discharge. This is how we typically regulate industrial stormwater discharges.
e. Outfalls 008, 009, 010, 012A and 012B
These are internal Outfalls and the pH limits are applied at the external Outfall. In addition, 40
CFR 423 does not require pH limits for the wastestreams discharged from these Outfalls.
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f. Outfall 008
The Correction will be made.
g. Outfall 009
The Clarification will be made.
h. Outfalls 010 and 011
Duke Energy has provided justification for the delay in implementing ELG requirements for
FGD wastewater. The new FGD limits in 40 CFR 423 were based on the 95-99% compliance
rate. Duke Energy, just like every other major facility in this state, operates on the assumption of
the 100% compliance rate. Therefore, the facility need time to upgrade treatment units to provide
reliable 100% compliance rate.
The limits for both Outfalls are based on the provisions of 40 CFR 423, there are no state or
federal regulations that would require the new FGD system to implement more stringent limits.
3. The Draft Permit Does Not Comply with Cooling Water Intake Requirements.
The Division approved the facility request for an alternative schedule in accordance with 40 CFR
125.95(a)(2). The permittee shall submit all the materials required by the Rule by May 31, 2023.
This is an accelerated schedule that includes: 1 year for the development of the sampling plan
and obtaining approval from the Division, 2 years of sampling to adequately characterize
seasonal variation, and 1 year for the report development. Based on the results of the studies, the
Division may require an implementation of the additional measures to reduce impingement and
entrainment of the aquatic organisms.
Duke Energy provided the following justification as Basis for Designation Belews Station as a
Closed Cycle Recirculation System:
A "closed -cycle recirculating system" is defined at 40 CFR 125.92 (c). The definition
addresses facilities with CCRS that withdraw from waters of the United States where the
impoundment was constructed for the purpose of providing cooling water for the facility:
"Closed -cycle recirculating system also includes a system with
impoundments of waters of the U.S. where the impoundment was
constructed prior to October 14, 2014 and created for the purpose of
serving as part of the cooling water system as documented in the project
purpose statement for any required Clean Water Act section 404 permit
obtained to construct the impoundment. In the case of an impoundment
whose construction pre -dated the CWA requirement to obtain a section
404 permit, documentation of the project's purpose must be demonstrated
to the satisfaction of the Director. This documentation could be some
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other license or permit obtained to lawfully construct the impoundment
for the purposes of a cooling water system, or other such evidence as the
Director finds necessary." 40 CFR 125.92 (c)(2).
Impoundments are further defined and discussed as a closed -cycle cooling system in the
rule's preamble, stating that:
"Impoundments are surface waterbodies that serve as both a source of cooling
water and a heat sink. As with cooling towers, impoundments rely on
evaporative cooling to dissipate the waste heat; a facility withdraws water
from one part of the impoundment and then discharges the heated effluent
back to the impoundment, usually in another location to allow the heated
water time to cool. Depending on local hydrology, impoundments may also
require makeup water from another waterbody. Impoundments can be man-
made or natural, and can be offset from other water bodies or as part of a
"run of the river" system (the latter are sometimes referred to as cooling
lakes)." 79 Fed. Reg. 48,334 (August 15, 2014)
The system at Roxboro meets the criteria for classification as a CCRS. Roxboro
withdraws cooling water from Hyco Lake which was constructed in a water of the United
States for the purpose of providing cooling water for the Carolina Power & Light
Company (now Duke Progress, LLC) Roxboro Steam Electric Plant prior to the Clean
Water Act 404 permitting program. The Carolina Power & Light Company received
authorization for the creation of Hyco Lake in April 1964 for the Roxboro facility.
Numerous documents issued by the State contain several statements and commensurate
justification that the purpose of Hyco Lake was to be "operated ... to reduce pollution [via
condenser cooling water recirculation] in the Hyco River" and is a "cooling pond":
• State of North Carolina Department of Water and Air Resources Permit 522 issued
May 4, 1964
• Carolina Power & Light Company, North Carolina State Stream Sanitation
Committee
"Application for Approval of Plans" dated April 13, 1964
• North Carolina Board of Water and Air Resources Permit 522 Certification dated
October 1, 1971
• North Carolina Environmental Management Commission Permit 2523 issued July
22, 1974
The permit issued by the State of North Carolina Department of Water and Air Resources
(the predecessor Agency to the North Carolina Department of Environmental Quality)
authorized "...operation of a 3,800 acre cooling lake for a design flow of 2,400,000,000
G.P.D., and the discharge of the effluent into the Hyco River, a tributary in the Roanoke
River Basin". The dam was completed in 1964 and Hyco Lake reached full pool elevation
in 1965.
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As also required by the definition, make-up water withdrawals attributable to the cooling
portion of the Roxboro cooling system have been minimized. The source of all makeup
water is the approximately 300 square mile Hyco Lake watershed. No other sources of
makeup water are currently available and none are planned.
In addition to minimizing withdrawals for make-up water to Hyco Lake, Roxboro also
minimizes cooling water withdrawals from Hyco Lake in multiple ways. First, Unit 4
operates on recirculating cooling towers that require only small volumes of makeup
waters. Those make up waters are taken from internal process areas consisting of Unit 1-3
cooling water discharge and the ash basin discharge flows. Second, the cooling water
system for Units 1-3 has several design features that increase their efficiency, including (a)
directing deeper, cooler water to the intake as needed to maintain efficiency by using
cooler water from deeper in the reservoir; (b) routing of cooling water discharges as far as
possible upstream from the cooling water intake (subject to constraints imposed by the
Department for thermal impact reasons); and (c) utilization on Unit 3 of a helper cooling
tower seasonally which reduces the thermal discharge load to the lake and allows for more
efficient cooling during the summer months. Third, as reflected in the company's
Integrated Resources Plans, filed with the North Carolina Utilities Commission, Roxboro
has operated since 2016 as an "Intermediate" rather than "Baseload" generation source.
The reduction in operating time has resulted in a reduction of average daily withdrawals
from greater than 800 MGD when the plant operated as Baseload to 592 MGD in 2018, as
reported in the station's annual water withdrawal reports.
The Division concurs with the justification provided by Duke on a provisional basis.
Based on 40 CFR 125.92 (c) the Director has determined that operating and maintaining
the existing closed -cycle recirculating system meets the requirements for a provisional
BTA. The final determination will be made upon review of the materials submitted by the
permittee. This determination is consistent with the EPA Region IV decision
regarding Robinson Station (South Carolina) and Belews station, and the EPA
Region III decision regarding North Anna Nuclear Power Station (Virginia).
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