Riverbend Steam Station (5)

1 ' '• e
RECEMED
DIVISION OF WAT,,! ; QUALITY
0 a JUN 3
Ai
WSwP h.'. ow
NCDENR MOORESVILLE REC,0i,AL OFFICE
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H Sullins Dee Freeman
Governor Director Secretary
Issue l " i
STAFF REVIEW AND EVALUATION
Compliance history
2
Benchmark exceedance
6
NPDES Stormwater Permit
3
Other Challenges:
• Power Plant— New SW Permit
8
Facility Name
Duke Energy Carolinas, LLC — Riverbend Steam Station
NPDES Permit Number
NCS000549
Facility Location
175 Steam Plant Rd, Mount Holly, NC (GASTON County)
Type of Activity
Steam Electric Generation
SIC Code
4911
Receiving Streams
Catawba River (Mountain Island Lake) 11- (114), See Figure 1
River Basin
Catawba River Basin, Sub -basin 03 -08 -33
Stream Classification
WS -IV, B, CA
G
Proposed Permit Requirements
See attached draft permit
X
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r
Monitoring Data
See application
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Response Requested by (Date)
June 27, 2011
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Central Office Staff Contact:
Return to: Robert'Patters n (919) 807 -6375
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Special Issues:
Issue l " i
Raiin 0Scale: 1 ,eas to -10 hard; G
Compliance history
2
Benchmark exceedance
6
Location (TMDL, T &E species, etc)
3
Other Challenges:
• Power Plant— New SW Permit
8
Difficulty Rating:
19/40
Special Issues Explanation
• Previously this facility only had an NPDES WW permit for its discharges (NC0004961)
Description of Onsite Activities:
Fossil - fueled electric generation plant with 4 active coal -fired generation units (generating capacity of 227 MW), 3
active oil or gas -fired combustion turbine units (30 MW each), and l out -of- service combustion turbine unit. The
station includes, a closed dry ash stack, 2 active ash settling basins, an out of service ash cinder pit, a closed and
capped ash stack, a scrap yard, construction spoil and laydown areas, a coal unloading and handling operation, a
wastewater treatment plant, electrical switchyards, 4.25 million gallon fuel oil storage tank, a warehouse,
transformers, a maintenance garage, and coal handling operation and storage yard Coal is shipped to the site via rail
lines. Fuel oil is shipped to the site via truck
Page 1 of 5

NCS000549
Documents Reviewed:
0 NPDES Stormwater Permit Application Materials (EPA Forms 1 & 2F)
0 National Heritage Program (NHP) Threatened and Endangered Species Database
0 SPU and NPDES Wastewater Permit Files
0 Central Files
0 303(d) List (2010 Assessment)
0 2010 Catawba Basinwide Plan
History:
Until now, the facility has only had a wastewater permit and sampled some stormwater outfalls as part of the NPDES
WW renewal application In 2010, Mooresville Regional Office staff inspected two Duke Energy facilities and
noted that this site needed a stormwater permit (see NPDES NC0004979 file) The Division prefers to issue a
separate NPDES SW permit rather than combine wastewater and stormwater requirements under one permit. The
attached permit was drafted to reflect the permitting strategy for all coal -fired power plants set by the Stormwater
Permitting Unit (SPU) in 2009 A note from the last MRO site visited stated that this plant may close in the next 5
years, but these plans were not yet finalized
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Page 2 of 5

NCS000549
Central Office Review Summary:
Owner's Other Permits
• NC0004961 — Wastewater permit (outfalls NPDES 001, NPDES 002, & NPDES 002A)
• 03788T32 — Air permit
• WQ0000452 — Distribution of residual solids permit
• NCD024717423 - RCRA
2 General Observations
12 SDOs, requested ROS to sample only SWO02 and SWO04
In 2009 the Stormwater Permitting Unit (SPU) established a strategy for all coal -fired power plants
The strategy includes a standard suite of parameters for analytical monitoring (see attached discussion)
Since then, at least four power plants have been monitoring stormwater discharges for those
parameters Elizabethtown Power LLC (NCS000352), Lumberton Power LLC (NCS000349), Progress
Energy's Mayo Steam Electric Power Plant (NPDES WW + SW NC0038377), and Progress Energy's
Weatherspoon Steam Electric Plan (NPDES WW + SW NC0005363)
The data from those facilities (12 samples total) shows Zn and Cu benchmarks exceeded most
often Those sites also have mercury levels in stormwater discharges that range up to 10 ng/1
3 Impairment This stream segment is impaired for low pH From the Basinwide Plan
"Lake monitoring was not conducted on Mountain Island Lake [AU 11- (114)] during this sampling cycle, however,
ambient monitoring station samples were collected during this cycle between February 2004 and January 2007
During that time, 12% of pH samples were below 6 su The state standard for pH is between 6 and 9 su
Exceedances only occurred in the first three years during the months of Marchand April The lake will appear on
the Draft 2010 Impaired Waters list for the first time due to pH standard exceedances The source of low pH is
unknown at this time, but has been seen basinwide "
The draft permit allows for monitoring of rain pH, and not respond to the tiers if the rain is <6 su
4 Threatened and Endangered None known
Analytical Monitoring Notes Three outfalls were sampled as part of the NPDES stormwater application These
outfalls (SW001, SW 002, and SW 003) were sampled in 2008 for the NPDES wastewater permit renewal
application, as part of a prior arrangement with DWQ Because we have adopted a consistent stormwater
permitting strategy for all power plants, SPU accepted these results without requiring samples from the other
outfalls for the individual permit application See application documents (Form 2F) The stream is impaired for
low pH, however none of the samples included pH testing
SW001 [Drains area with powerhouse roof, main swithchyard, and paved areas, drains through oil trap tank]
Aluminum (0 915 mg/1), copper (0 0684 m6I1), and zinc (0 863 mall) levels were above benchmarks of 0 75
mg/l, 0 007 mg/l, and 0 067 mg/l, respectively Cadmium (0 0013 mg/1) level was right at the benchmark of
0 001 mg/i Selenium (0 062 mg/1) level was slightly above the benchmark of 0 056 mg/1 Radioactive
substances were also reported There are no stormwater benchmarks for these substances, but there are water
quality standards based on annual averages No results reported for antimony, lead, or thallium
SWO02 [Drains area with rail lines that carry coal, fuel oil unloading station, above ground fuel oil piping,
switchyards, combustion turbine buildings, and paved parking, drains through oil trap tanks] One Oil &
Grease (27 6 mg/1) level was elevated, but not above the benchmark of 30 mg/I The other O &G sample was
BDL Aluminum (1 58 mg/1), copper (0 0333 mg/l), and zinc (0 486 mgll) levels were above benchmarks of
0 75 mg/l, 0 007 mg/l, and 0 067 mg/l, respectively Cadmium (0 0012 mg/1) and Selenium (0 0562 mg/1) levels
were right at the benchmarks of 0 001 mg/I and 0 056 mg/l, respectively Radioactive substances were also
reported There are no stormwater benchmarks for these substances, but there are water quality standards based
on annual averages No results reported for antimony, lead, or thallium
SWO03 [Drains area with rail lines that carry coal, switchyard, portion of earthen fuel oil containment dike,
Page 3 of 5

NCS000549
and above ground fuel oil piping] BOD (72 9 mg/1) and COD (233 mg/1) levels were above the benchmarks of
30 mg/l and 120 mg/I, respectively TSS (151 mg/1) level was above the benchmark of 100 mg/l TP (1 6 mg/1)
was elevated, but not above the benchmark of 2 mg/1 Aluminum (0 753 mg/1), copper (0 0533 mg/1), and zinc
(2 29 mg/1) levels were at or above benchmarks of 0 75 mg/I, 0 007 mg/l, and 0 067 mg/l, respectively
Manganese (1 38 mg/1) was above the WS -IV water quality standard of 0 20 mg/l, but there is no benchmark due
to its widespread background presence across the state
The company is requesting Representative Outfall Status (ROS) for four outfalls Request form attached
Central Office observations and questions for Region to consider:
• Groupings seem to be for similar industrial activities inmost cases, limited data to date some outfalls
don't have any monitoring data
• Should we require most outfalls to be sampled at least once or twice during the permit cycle'? There are
several included in this request that have never been sampled
• The requested representative outfalls do not include SW 001, which drains a potentially significant
pollutant exposure area (ie the main switchyard and the powerhouse roof) Does the MRO agree with
not monitoring this outfall?
• The requested representative outfalls do not include SW 008, which drains a potentially significant
pollutant exposure area (ie ash pipelines, ash stack, and cinder pit) No sampling was performed for
this outfall Does the MRO agree with not monitoring this outfall9
• The requested representative outfalls do not include SW 003, which had a sample well above the WS -IV
water quality standard for Manganese Does the MRO agree with not monitoring this outfall
• Wind rose analysis (Tom Anderson, Division of Air Quality) for the Charlotte area shows winds are
predominantly from the southwest most of the year here, with more winds from the
northeast in the winter This corresponds to winds blowing from the plant powerhouse towards
the lake and Drainage Area 8 most of the time, and blowing towards Drainage Area 1, 2, and 3 in
the winter Might consider deposition potential from stacks in these general directions when
considering ROS, also consider that the majority of deposition would occur closest to source
6 Qualitative Monitoring otes N /A, new permit
Revised Permit Recommendations: Analytical Monitoring:
1 Proposed analytical monitoring is consistent with the Stormwater Permitting Unit's strategy for all power plant
permits established in 2009 For more information, see attached discussion The draft includes
a Semi- annual monitoring for 13 priority metals (Ag, As, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, TI, Zn) + Al
& B, with benchmarks where available
b Semi- annual mercury (Hg) monitoring with more sensitive method 1631 E but no benchmark (or
obligation to monitor monthly in Tier 2)
c Semi- annual monitoring for COD, TSS, pH, sulfates, and O &G
d Requirement to submit annual data summary to DWQ regional office
2 Coal pile runoff discharge (subject to stormwater effluent guidelines limitations) is covered under the
plant's wastewater permit (NC0004961), coal yard runoff is directed to NPDES WW outfall 002 (ash
settling basin) Coal yard sump overflow is under the same permit (002a)
3. The company has requested Representative Outfall Status (ROS) for two (2) stonnwater outfalls SWO02 and
SWO04 The draft permit does not specify any representative outfalls, review and approval by Regional Office
pending (See 5 above for discussion)
Page 4 of 5

NCS000549
Recommendations: Based on the documents reviewed, the application information submitted on May 11, 2011
sufficient to issue an Individual Stormwater Permit
Prepared by (Signature)
Stormwater Permitting U
Date
Date 5 /2(�,Zp lJ
Concurrence by Regional Office Date 6 3U Zo
RO Water Quality Supervisor Y ► 1 Date 1
Regional Office Staff Comments (attach additional pages as necessary)
Page 5 of 5

D
Ju1_ r z 2011
To. Robert Patterson 15 ry TO ��O June 3 0, 2011
From Rob Krebs We�"�� cn
Prepared By- Michael ParkerM
NCS000549 Duke )Energy Carolinas, LLC - Riverbend Steam Station
Gaston County
Site inspection conducted on June 22, 2011, by Michael Parker Facility contact. Mr Mark McGary
(704) 634 -7098 (cell) and Mr Steve Jones, Plant Manager This request is for a new SW permit This
facility is in the business of producing electricity via coal fired turbine generation, however, Duke
Energy has slated this plant for closure in 2015. The SW outfalls at this site drain to Mountain Island
Lake, which will likely be listed as impaired for pH in upcoming basin plans (source unknown).
A portion of the SW generated at the Riverbend Steam Station (RSS) site is routed through two yard
drain sumps which carry the SW to an existing ash basin This ash basin discharges through outfall
002, which is covered under the facilities existing NPDES wastewater permit (NC0004961) There
are, however, areas of the site where SW drains back to surface waters (Mountain Island Lake, WS -IV.
B, CA), and these areas (and the associated outfalls) are to be covered under the subject SW permit
The only SW testing data available for review in this application was collected in 2008 at SW outfalls
SWOOI, SWO02, and SWO03 There are 12 existing SW outfalls that Duke Energy has submitted for
inclusion in the proposed permit In their,nermit application, Duke Energy has requested that outfall
SWO02 be representative of outfalls S WOO 11,,�SWO02;)SWO03, SW006, and SWO08 Also requested in
the permit application is for outfall SW004 be designated as representative of outfalls SWO04; SW005,
SWO07, SWO1O,— SWOH7S- NV012, and SWO14
During the site visit, it was noted that SW outfall SWO04 drains an area that is not part of the industrial
activities that occur on this site Furthermore, outfalls SWO10, SWO11, and SWO12 receive SW from
activities not related to the industrial operations at RSS These outfalls (in addition to outfall SWO04)
should not be included in the permit as monitored outfalls. After some discussion with Duke Energy
staff, it was decided that instead of designating outfall SWO04 as a representative outfall, it would be
more prudent to establish outfal'LS -W006 as representative of outfalls SWO03 and SWO08 The 2
drainage area leading to outfall SWO06 contains a considerable amount of the industrial activity on this 6
site and is more representative than using SWO04 Mr McGary was receptive of this suggested
change
SW outfalls SWO02 and SWO06 receive drainage from areas that have areas that are either graveled or
covered with aging (broken) asphalt Fines associated with the gravel and broken asphalt may be
problematic for RSS staff based on analytical testing conducted at this facility in 2008 Unless
additional measures are implemented to control the off -site movement of the fines associated with the
gravel and broken asphalt in these areas, this facility will likely have difficulty in consistently
complying with the benchmark TSS levels proposed in the draft SW permit. The mobility of these
particles may also help contribute to the other elevated benchmark values noted in the testing data
submitted with the permit application The SW from outfalls SWO02 and SWO06 both pass through oil
tiap tanks before they discharge into Mountain Island Lake. Maintenance of these oil trap tanks will
be important with regards to obtaining consistent compliance with the proposed benchmark values

Page Two
Analytical testing data submitted with the permit application for outfalls SW001, SW002, and SWO03
reflected a nurnber of parameters where test results have exceeded the proposed benchmark values for
Aluminum, Chromium, Copper, Zinc, Total Suspended Residue, BOD, and COD This SW testing
data was collected in 2008 in conjunction with the renewal of the site's NPDES wastewater permit
Any changes at the RSS since 2008 may result in a change in the characteristics of the site's SW,
which would render the submitted data as not being indicative of current site conditions Additional
testing will be necessary to determine whether or not compliance with the proposed benchmark values
can be consistently obtained.
SW outfall SWO01 drains the main switchyard and powerhouse building and should be included as a
monitored outfall If through future testing the resulting analytical data is found to be consistent with
the data at outfall SWO06 (and consistently well below benchmark values), then representative outfall
status can be considered at that time
Outfall SWO08 drains a significant portion of the site, including the ash stack, pipelines, and cinder pit,
however, this outfall rarely (if ever) discharges. The outfall discharge structure (riser pipe) is located
in the cinder pit and all SW collected in drainage area No 8 infiltrates into the ground and does not
make it to the outfall structure of SWO08 This area was at one time an ash storage /disposal area, so
any SW in this area would likely infiltrate into the ground rather that runoff and discharge at SW008.
Outfall SWO03 is not included as a monitored outfall due to the fact the only area where industrial
activities occur in this drainage area is a switchyard that sits up gradient of the main plant. Any release
from this area will enter an oil rupture collection tank before it would enter the SW drainage system.
The industrial activities in this area are consistent with the activities in drainage area No 2, which is
recommended as a representative (monitored) outfall Monitoring of outfall SWO03 is not
recommended at this time
In conclusion, it is recommended that the subject SW permit be issued with consideration given to the
comments /recommendations as contained in this report
/mlp
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