Riverbend Steam Station (14)

Duke
-, Energy,,
August 11, 2011
Mr. Robert D. Patterson, P.E.
Division of Water Quality
Stormwater Permitting Unit
North Carolina Department of Environment
and Natural Resources
1617 Mail Service Center
Raleigh, NC 27699 -1617
Subject: Duke Energy Carolinas, LLC
Draft NPDES Stormwater Permit Comments
Riverbend Steam Station
Permit No. NCS000549
Dear Mr. Patterson:
DUKE ENERGY CORPORATION
526 South Church St.
Charlotte, NC 28202
Mailing Address:
PO Box 1006
Charlotte, NC 28201 -1006
AUG
WETLANDS AND STORMWATER BRANCH
Duke Energy Carolinas, LLC (Duke Energy) recognizes the need to be protective of surface
waters receiving stormwater runoff from our facilities, however, these efforts must be
reasonable and cost effective. Duke Energy maintains that many of the requirements mandated
by this permit are of little or marginal value in terms of environmental protection and therefore
significant revisions are warranted. Furthermore, Riverbend Steam Station is currently
scheduled to cease operations by December 31, 2014.
We have reviewed the subject draft stormwater permit for the Riverbend Steam Station and
submit the following comments:
a. Our permit application proposed that representative outfall status (ROS) be granted for
outfall SWO02, inasmuch as SWO02 is representative of those outfalls surrounding the
station powerhouse where industrial activities are concentrated. DWQ is specifying ROS
status (and therefore quantitative sampling) for SWO01, SWO02 and SW006. These
three outfalls are the discharge outfalls from the oil trap tanks at the station. SWO02
represents the greatest risk to stormwater based on the size of the contributing drainage
area and the various industrial uses within the area, therefore, SWO02 is adequately and
conservatively representative of SWO01 and SW006. All requirements for quantitative
sampling of SWO01 and SWO06 should be removed from the permit.
b. Duke Energy agrees with the DWQ interpretation that SW004, SW010, SW011 and
SWO12 are not part of industrial use areas of the site, and therefore are not to be
monitored. Based on this same interpretation, SWO05 and SWO14 should be excluded
from all monitoring requirements as well. SWO05 essentially drains 5 acres of grassed
lawn areas along the station access road in the extreme southeastern area of the station
property. The drainage area for SWO05 includes no industrial activities. SWO14 drains
an isolated 0.02 acre grassed basin area located on the east side of the station intake
canal. This insignificant drainage area includes only the station septic tank access
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manways Providing access to this outfall is not feasible (reference attached supporting
information), and the likelihood of obtaining a qualitative sample from this insignificant
outfall is remote
c Most of the stormwater outfalls at Riverbend Steam Station are currently inaccessible
(reference attached supporting'information) Providing safe and secure access to these
outfalls for sampling and monitoring will be difficult and costly Providing access to
SW006 and SW014 is not feasible due to the nature of the discharge locations on the
steep riverbank of the intake canal Furthermore, there are no collection points available
between the outfalls for SW001, SW002 and SW006 and their associated oil trap tank
outlets Quantitative or qualitative samples collected from within these oil trap tanks
would not be representative of the actual discharges We believe the difficulty and
expense of'providing access to,all inaccessible outfalls,for qualitative monitoring
purposes is unreasonable, and is not Justified from a stormwater protection standpoint
Considering that the Riverbend Steam Station is scheduled to cease operations at the
end of 2014, Duke Energy proposes that the permit be amended to reflect the following
requirements for quantitative and qualitative monitoring
i Duke Energy will construct safe access to SW002 and SW003,
ii Quantitative samples will be collected from SW002 and SW003 only,
III Qualitative monitoring will be performed at SW007 and SW008 only,
IV No sampling or monitoring will be performed at SW001, SW005, SW006 nor at
SW014
d Part'l1, Section B of the draft permit mandates analytical and qualitative monitoring for a
host of parameters, including 15 metals, O &G, and sulfate Based on historical
stormwater and lake monitoring data, there is no scientific basis for inclusion of these
parameters Many of these parameters have never been detected in historical
stormwater samples collected from . Outfalls SW001, and SW003 This data has been
submitted to DWQ as part of the NPDES permit renewals In addition, most of these
parameters are excluded from monitoring requirements at the ash basin discharge outfall
in the NPDES permit based on reasonable potential analyses to exceed state water
quality.standards Our NPDES permit does not mandate sampling for Ag, Be, Cd, Cr, Pb,
Sb, TI, Al, B, COD, nor SO4 at the ash basin discharge Certainly this discharge
represents the worst case impacts to surface waters in terms of mass loading associated
with the facility Therefore, these additional parameters should be removed,from the
permit monitoring requirements
e There is no scientific Justification for many of the benchmark values listed in Part II,
Section B, Table 3 There should be a significant water quality issue, such as a 303 (d)
listing, to Justify the requirements for monitoring of any benchmark values ,in the permit
These drivers do not exist for the receiving water body at Riverbend Steam Station
(Mountain Island Lake) Furthermore, exceeding a benchmark value gives the
appearance to,third parties that,a water quality standard has been exceeded We believe
this is inappropriate and will cause more public concern than is intended Therefore, we
request that all benchmark values be removed from the permit that do not relate to actual
existing water quality issues in the receiving water body
f `The requirement for EPA method 1631 E low level mercury analysis stated in Part II,
Section B, Table 1, Footnote 4 should be removed The quality control measures
necessary for ensuring quality data cannot be easily met in the conditions expected
during "wet weather" sampling Wet deposition has long been understood as a mode of

transport for Hg in the atmosphere Sampling during a storm event, in which rain is
actively falling, could pose contamination issues, for field blanks (also required by
Footnote 4) collected in this environment Contaminated field blanks would call into
question samples collected alongside those blanks Considering the likelihood of
collecting storm water samples during active rainfall, it is very likely contaminated blanks'
would confound the interpretation of the mercury data and compromise the integrity of the
data, Should mercury analysis be required, Duke Energy advocates the Cold Vapor
Mercury Analytical Method 245 1
g Part II, Section B, Table 2 comments of the draft permit requires a separate signed
Annual Summary DMR copy to be submitted to, the local DWQ Regional Office by March
1st of each year Part III, Section E, Item 1 indicates that sampling results must also be
submitted on the DMR forms within 30 days of obtaining the analytical results Requiring
,this separate Annual Summary DMR submittal is redundant and time consuming
Therefore, we request that the requirement for submittal of'the Annual Summary DMR be
removed from the permit
h Part III, Section E, Item 1 of the draft permit states that, in the event of no discharges
occurring during the reporting period, Duke Energy is required to submit a DMR "within
30 days of the end of the three month sampling period "' This sentence should read
"within 30 days of the end of the six month sampling period"
i Part II, Section A, Paragraph 7 states that "The permittee shall provide certification in
writing in accordance with Part III, Standard Conditions, Section B, Paragraph 5" This
sentence should read "in accordance with Part III; Standard Conditions, Section B,
Paragraph 3'
Please contact Mark McGary@duke- energy com or at 704 -634 -7098 if you have any questions
or need any additional information
Sincerely,
fMarkMcGary, P E
Environmental, Health & Safety
Attachment

Outfall SW001
24" CMP
Current accessibility for sampling /monitoring: Inaccessible due to steepness of
embankment, vertical drop to intake canal,
and overhanging outlet.
Sample collection probability: Possible only if a safe means of access is provided, and
then only from cutout in pipe. Sample collection upstream
of outlet is not possible due to oil trap tank.

Outfall SW002
21" C IVI P
Current accessibility for sampling /monitoring: Inaccessible due to steepness of
embankment and overhanging outlet.
Sample collection probability: Possible only if a safe means of access is provided, and
then only from cutout in pipe. Sample collection upstream
of outlet is not possible due to oil trap tank.

Outfall SW003
36" CMP
Current accessibility for sampling /monitoring: Inaccessible due to steepness of
embankment.
Sample collection probability: Possible only if a safe means of access is provided.

Outfall SWOOS
24" CMP
Current accessibility for sampling/monitoring: Accessible.
Sample collection probability: Likely.

Outfall SW006
36" CMP
Current accessibility for sampling /monitoring:
Inaccessible due to steepness of riverbank and
vertical drop from discharge point.
Sample collection probability:
Not feasible at outlet. Sample collection upstream
of outlet is not possible due to oil trap tank.

Outfall SWO07
24" Steel Pipe
Current accessibility for sampling /monitoring: Outlet inaccessible due to fence. Inlet is
accessible
Sample collection probability: Unlikely due to limited extent of drainage area.

Outfall SW008
CMP
Current accessibility for sampling /monitoring: Accessible.
Sample collection probability: Unlikely due to riser inlet configuration and stormwater
storage capacity of detention pond.

Outfall SW014
8" CM IR
Current accessibility for sampling /monitoring: Inaccessible due to steepness of
embankment, vertical drop of outlet, and
fence.
Sample collection probability: Not feasible at outlet, and unlikely due to limited extent of
drainage area.