NC0004987_Supplemental Information_20171206

DUKEPaul Draowtch
ENERGY® Senior Presde
Environmental, Health
h &Safetyty
526 S Church Streei
Mad Code EC3XP
Charlotte, NC 28202
[phone]
December 6, 2017
Ms. Julie Gryzb RECEBVEMENROWR
North Carolina Division of Water Resources
1617 Mail Service Center DEC 12 2017
Raleigh, NC 27699-1617
Water R@SOIdPC@5
Permitting Section
RE: NPDES Permit No. NC0004987
Marshall Steam Electric Plant
Supplemental Information — ELG Applicability Dates
Dear Ms. Gryzb,
On May 9, 2016, Duke Energy Carolinas, LLC (Duke) submitted a justification for the appropriate
applicability dates for compliance with the 2015 revisions to the Steam Electric Effluent Limitation
Guidelines (2015 ELG Rule) for the Marshall Steam Electric Plant (Marshall). The justification
demonstrated that the appropriate applicability date to comply with the more stringent best available
technology (BAT) limits for flue gas desulfurization (FGD) wastewater and bottom ash transport water
(BATW) was January 31, 2021. This applicability date was adopted in the NPDES Permit for Marshall
issued on September 9, 2016. On September 18, 2017, U.S. EPA issued a final rule postponing the
compliance dates for the more stringent BAT limits for BATW and FGD wastewater. As a result of that
final rule, Duke is submitting this supplemental information and requesting that North Carolina
Department of Environmental Quality (NCDEQ) postpone the applicability date for the no discharge
limit for BATW imposed on Outfall 002 and the limits for arsenic, mercury, nitrate/nitrite and
selenium imposed on internal Outfall 004 and internal Outfall 006 until December 31, 2023 and
include a reopener clause that allows the permit to be modified to implement the revised ELGs in the
event the U.S. EPA adopts new compliance deadlines and/or further revisions to the rule.
BACKGROUND
On May 9, 2016, Duke submitted a written justification to NCDEQ regarding appropriate compliance
dates for the new best available technology (BAT) limits for bottom and fly ash transport water and flue
FGD wastewater discharged pursuant to Marshall's NPDES permit. Since that time, on August 11, 2017,
the EPA Administrator signed a letter announcing his decision to conduct a rulemaking to potentially
revise the new, more stringent BAT effluent limitations and pretreatment standards for existing sources
(PSES) in the 2015 ELG rule that apply to BATW and FGD wastewater. In a follow-up action, EPA filed a
motion on August 14th with the Fifth Circuit Court of Appeals to put portions of the ELG appeal on hold,
while EPA reconsiders certain ELG limits. Within the motion, EPA stated its intent to conduct a
rulemaking to potentially revise the more stringent BAT effluent limitations and PSES for BATW and FGD
wastewater. This motion was granted by the Fifth Circuit Court of Appeals on August 22"d. Based on
these actions by the EPA Administrator, Duke requested the removal of the no discharge limit for BATW
imposed on Outfall 002 and the limits for arsenic, mercury, nitrate/nitrite and selenium imposed on
internal Outfall 004 and associated applicability dates. However, in a subsequent rulemaking
(Postponement Rule), the earliest compliance date for the more stringent limits for BATW and FGD

I
Ms. Julie Gryzb
December 6, 2017
Page 2
wastewater were postponed for a period of two years (i.e. until November 1, 2020), while EPA conducts
a rulemaking potentially revising the limits (82 Fed. Reg. 43,494 (Sept. 18, 2017)). Within the preamble
of the Postponement Rule, EPA projects it will take approximately three years to propose and finalize a
new rule (Fall 2020) and anticipates that the next rulemaking will address the compliance dates for the
revised BAT limits for BATW and FGD wastewater in some fashion. Furthermore, the intent of the
Postponement Rule is to preserve the status quo and to avoid any unnecessary expenditure for
compliance with limitations and standards for FGD wastewater and BATW, because those BAT
determinations and associated limits may change as a result of further rulemaking (82 Fed. Reg. at
43,496 (Sept. 18, 2017).
REQUESTED ACTION
Based on the Final Postponement Rule, Duke now respectfully requests that NCDEQ set the applicability
date for new FGD wastewater and BATW effluent limits as December 31, 2023. In addition, Duke
requests the inclusion of a reopener clause to allow the permit to be modified in the event U.S. EPA
revises the compliance deadlines and/or the limits for BATW and FGD wastewater. Duke believes a
revised applicability date and reopener clause is appropriate because NCDEQ will need sufficient time to
modify the Marshall NPDES permit to incorporate U S. EPA's revised effluent limits after its new
rulemaking, and Duke will need sufficient time to develop and implement a compliance plan for those
new effluent limits. Even though capital projects are underway to meet the compliance obligations
under the North Carolina Coal Ash Management Act (CAMA) and Coal Combustion Residual (CCR) Rule,
additional planning and operational and maintenance (O&M) expense is required to comply with the no
discharge limit of BATW and to meet the more stringent BAT limits for FGD wastewater. Without a
revised applicability date, Duke would bear the planning and O&M costs to comply with limits that may
be determined inappropriate and unjustified.
Sincerely,
Paul raovit
Senior Vice President
Environmental, Health and Safety
cc- Richard Baker
Shannon Langley