HomeMy WebLinkAboutNCS000572_Dan River Add Info Response_20150922+f DUKE
ENERGY.
September 22, 2014
Rcopy
864 S. Edgewood Rd.
Eden, NC 27288
RECEIVED
SEP 2 2 2014
DENR-LAND QUALITy
STORMWATER PERMITTING
Mr. Bradley Bennett Via Email. bradley.bennett@ncdenrgov
Supervisor, Stormwater Permitting Program
North Carolina Department of Environment and Natural Resources
Division of Energy, Mineral, and Land Resources
1612 Mail Service Center
Raleigh, NC 27699-1612
Subject: Dan River Steam Station
NPDES Stormwater Permit Application
Duke Energy Response to Additional Information Request
Dear Mr. Bennett,
Duke Energy Carolinas, LLC (Duke Energy) presents the following information to the North
Carolina Department of Environment and Natural Resources (NCDENR) — Division of Energy,
Mineral, and Land Minerals in response to NCDENR's additional information request dated
August 26, 2014. The request was submitted following Duke Energy's August 1, 2014 submittal
of a National Pollutant Discharge Elimination System (NPDES) stormwater permit application
for the Dan River Steam Station, located in Rockingham County, North Carolina. For ease of
reference, NCDENR's excerpted queries appear in italics below, followed by Duke Energy's
(DE) associated response.
NCDENR: Analytical sampling results were provided for stormwater discharges from a July
15, 2014, rain event. The 10 sample locations included eight stormwater
discharge points (SW001,003,004,005, 006, 007, 008, and 010), plus roof
drainage from the power house building (apparently not a stormwater discharge
location), plus a discharge point characterized as the former NPDES outfall
009(wasiewater outfall). Please clarify for us why the former wastewater outfall
was submitted as part of the stormwater sampling effort.
DE Response: The outfall in question was previously a dual stormwater/wastewater outfall. The
NPDES outfall 009 was removed from the current NPDES permit when it became
effective on March 1, 2013. The wastewater that was discharged through this
outfall was non -contact cooling water from the combustion turbines that were
located on site. These CTs were shutdown in 2012 and have been demolished. In
terms of Storm water, 13.4 acres of facility potentially drains to this area. Due to
discussions with the NCDENR and sampling results, we are proposing this outfall
no longer be classified as a storm water outfall.
YgO:)iB
NCDENR: We note that the site map drawing identifies Future Outfall 009, but that no
sampling data is presented for that outfall. We interpret the narrative description
of the outfall to indicate that there is no discharge from SW009 presently. Please
confirm our understanding of the narrative description, or provide sampling data
for the outfall. Our understanding was that Duke would follow the same format
as the Riverbend application in subsequent application submittals, including
sample results from all stormwater outfalls. Please provide the missing sampling
results for Outfall SW009, or provide a schedule for sampling it, or provide a
clarification of the circumstances that indicate that sampling it is not appropriate
at this time.
DE Response: Proposed outfall SW009 is located in a groin area formed by the primary ash
basin. This is the location of the 48" pipe, which has been grouted shut. The
water that collects in this area is currently being pumped to the secondary ash
basin. The water currently contains ash contact water. Until this area is
addressed, a valid representative sample cannot be pulled. Looking at the
sampling data portion of the application, there appears to a misprint. The sample
data labeled drains to future Outfall SWO10 actually drains to future Outfall
SW009. Future Outfall SWO10 is located at the inlet to the plugged 36" pipe.
Water from this area is currently pumped to the primary ash basin. The water that
collects in this area is storm water and potentially contact water from the 36"
pipe. Until the inlet of the 36" pipe is permanently closed, a valid representative
sample cannot be collected. In addition to the water that collects at the inlet of the
36" pipe, water from the drainage areas around the dry ash stacks will be
conveyed through the future outfall, once the area around the dry ash stacks has
been addressed in the ash basin closure plan. Currently this water gravity feeds to
the secondary ash basin. Until this area is addressed, a valid representative
sample cannot be collected This area has very little contributing drainage area,
making obtaining a sample difficult during a storm event. Pumped stormwater
flows (non -contact water) from the area above the 36 -inch pipe and from the
Dredge area are proposed to be discharged at this location, but will not be
discharged until approved by NCDENR DWR Stormwater.
NCDENR: Please provide details (dates, locations on the .site, drainage areas impacted, etc.)
about the present and past storage and/or releases of Polychlorinated biphenyl
compounds (PCBs) on site. If there were any known releases, please discuss
actions taken to remediate any areas affected. Include information about which
drainage areas might have been impacts by PCBs.
DE Response: Historically, this facility utilized mineral oil -filled electrical equipment that may
have had low levels of PCBs. Other minor sources that may have contained PCBs
were lighting ballasts, capacitors, etc. This use dates back to original start of
operations at the site in 1949. All known PCB oil -filled equipment has been
removed or reclassified. Stormwater drainage for in-service mineral oil -filled
electrical equipment that may have had low levels of PCBs flowed to the site's
ash ponds and discharged through the NPDES permitted wastewater outfalls.
Stormwater drainage for in-service mineral oil -filled electrical equipment that
may have had low levels of PCBs may also have drained to outfalls SW001,
SW002 and SW004. The facility is completing minor PCB contaminated soil
cleanups adjacent to past transformers that serviced the now retired and
demolished combustion turbines at the site. Two transformers that contained oil
in excess of 50 ppm PCB had minor soil/gravel staining that is being excavated
and removed from the site. The soil around these transformers is being cleaned
up to below 1 ppm with the excavated soils sent to Emelle, Alabama for
disposal. This area drained to former NPDES outfall 009.
NCDENR: The graphic presentation of the site sub drainage areas is visually confusing as
submitted. Understanding the extent of the sub drainage areas feeding each
stormwater discharge point is a key element in our review of the permit
application. Please revise the site map drawing to more clearly delineate the sub
drainage areas feeding each stormwater discharge point. The graphic
presentation needs to be readily understandable so that our review can proceed.
Drawing C-002 should require only minimal graphic changes to help us easily
understand the site sub drainage areas.
DE Response: Bolder colors for drainage areas and lighter/thinner line work for existing
conditions (features, grades, etc.) have been added to the stormwater figures for
clarity. Please see the attached updated drawings.
NCDENR: In accordance with item V of the EPA Form 2F application, please confirm that
Duke has observed all stormwater outfall conveyances on the site, and that Duke
is reporting that only SW005 contains non-stormwater flows, and that Duke has
reason to conclude that the observed additional flow is groundwater only. For
future reference on other stormwater applications for this facility or for other
Duke facilities, if any outfalls either were not observed, or included non-
stormwater flows, please detail those conditions in EPA Form 2F. Also, if any
other discharges have occurred during dry periods please indicate hou, those
discharges are currently permitted, or will be permitted.
DE Response: Duke Energy observed all stormwater conveyances on the site on July 3, 2014 and
only SW005 contains non stormwater flow. We believe that the flow is
groundwater because we had no precipitation for 2 weeks prior to application
submittal, and there should be no other source of overland flow to that outfall
Future Outfall 009 and 010 were not observed, but the potential is there for non
stormwater flow due to ground water.
NCDENR: We understand that the site is undergoing demolition of the coal fired plant.
Please provide a schedule and narrative description of the demolition activities
that could impact stormwater discharges. Our concern is that the conditions of
the stormwater permit should anticipate changing site conditions during the
demolition period. We want to check whether conditional provisions addressing
demolition should be written into the permit and whether the provisions might be
structured to lapse when the demolition is complete.
DE Response: Please see the attached schedule. There are several projects that are either
planned or underway at the Dan River Steam Station with regards to
decommissioning. This includes decoupling of the CTCC raw water intake and
wastewater discharges that were expected to be complete in July, 2014, but have
been delayed; part of the project also includes the removal of power distribution
equipment. Once the new raw water system has been commissioned and Power
Delivery has removed switchgear/relays from the powerhouse, Duke expects the
powerhouse to be completely de -energized and turned over to the
abatement/demolition contractor for completion of the demolition work. This
work is expected to continue from mid -2015 until mid -2016.
Several other projects that may affect stormwater discharges from the site are in
the planning/permitting stages including Coal yard restoration, diversion of storm
water from the area currently draining through former NPDES Outfall
009/SW005, diversion of storm water from the area upland of the grouted 48"
pipe to the Settling Pond, repair of the Settling Pond overflow pipe, closure of the
36" pipe under the basins, and storm drainage from the [Dredge] area between the
two ash stacks as part of the ash basin closure scope.
Coal yard restoration was originally expected to be completed following
demolition. The current storm drainage system directs storm water from this area
to the yard sump. Since the pipe failure in February, Duke has pursued
temporary diversion of the sump discharge away from the ash basins and toward
the Settling Pond by use of pumping and treatment packages where needed. This
temporary diversion/treatment would be needed until the basins are removed and
the storm water can be directed over their current footprints.
An additional project includes the diversion of storm water from the area
currently draining through former NPDES Outfa11009 (is this SW009 or NPDES
Outfal1009?)/SW005 and storm water from the area upland of the grouted 48"
pipe to the Settling Pond. Before the currently proposed diversion can be
implemented, the area upland of the grouted 48" pipe must be addressed. Duke is
pursuing permits to perform this remediation as it will impact an area with
wetland features.
Another project currently under development is a proposallspecification to repair
the Settling Pond overflow pipe. This scope was previously expected to be
implemented as part of site restoration in 2016, but is currently expected to be
implemented between commissioning of the new raw water system and the return
of the abatement/demolition contractor in 2Q15.
In addition, we are expecting to address the closure of the recently plugged 36"
pipe under the basins and the storm drainage from the area between the ash stacks
as part of the ash basin closure scope. Our consultant has proposed the diversion
of storm water from both of these areas to a new storm water outfall downstream
of the secondary ash basin (Future SW Outfall 010). Before this canbe
implemented, the area between the ash stacks must be addressed in the ash basin
closure plan. The area currently drains to the secondary ash basin, which serves
as treatment for the ash contact water. The implementation of this or another
strategy to redirect storm water flows from these areas needs to be an integral part
of the ash stackfbasin closure scope.
NCDENR: Perhaps related to the demolition and the anticipatedfuture conditions, some
outfalls are labeled on the site plan as.former and some as,future ". Please clarify
for us the conditions that pertain at each outfall so characterized (Some limited
explanation is already contained in the application for Future Outfall SW009 and
future SW010.) Again, our concern is to access how to construct the permit
conditions to account for discharges that may change over the term of the permit,
or might ion the recent past have constituted a permitted outfall.
DE Response: Please see the attached updated narrative for clarification of the "former" outfalls.
NCDENR: Similarly we anticipate that the closure of the site's ash ponds may soon be
underway, and that the activity may be begun and completed within the term of
this stormwater permit. We would expect that some aspects of the ash pond
closure activity may present the potential for stormwater pollution (for example
activities such as transport of ash along on-site haul roads). In so far as is
possible at this point in time, please provide information on the ash pond closure
that could inform our drafting of the stormwater permit. Aspects such as the
location of haul roads, time schedules, and site modifications necessary to
accomplish the undertaking would help its to assess how the permit should
address the stormwater risks from the activity.
DE Response:: This work would start immediately upon confirming the destination for the ash,
completing engineering for infrastructure to accommodate the closure strategy,
and securing the necessary permits. Once those details are in place, we would
expect to complete this work within 24 to 30 months. Any movement of ash will
be dealt with in a manner consistent with current operations at existing Duke ash
handling facilities. This may include, but is not limited to truck wash/wheel wash
at ash loading or unloading areas,lined/sealed hauling containers/vehicles, dust
control, haul route erosion control. These processes help to maintain the
segregation between contact and non -contact stormwater, and help to mitigate
generation of contact water by haul road areas.
Duke Energy appreciates the opportunity to respond to NCDENR's request for additional
information. Should you have any questions regarding this submittal, please contact Mr. Steve
Cahoon at (919) 546-7457 or steve.cahoon@duke-energy.com.
duke-energy.com.
I certify, under penalty oflaw, that this document and all attachments were prepared ender my direction or
supewision in accordance with a system designed to assure that qualified personnel properly gather and evahate
the information submitted Based on my inquiry of the person or persons who manage the system, or those persons
directly responsible for gathering the information, the information submitted is, to the best of my knowledge and
belief, true, accurate, and complete. l am aware that there are significant penalties for submitting false information,
including the possibility ofJines and imprisonment far knowing violations.
Sincerely,
Duke Energy Carolinas, LLC
Glenn E. Harris
General Manager, Rockingham CT/ Dan River CC
cc: Linda Hickok, Duke Energy Progress, Inc.
Steve Cahoon, Duke Energy Progress, Inc.
DEMLR Winston-Salem Regional Office
DEMLR Stormwater Permitting Program Files
DWR Central Files
iITi MIM
To
From
Date
Subject
Steve Cahoon File no
Joshua Bell, PE cc
Thursday 9/18/14
TMI I M�0 V
6226.14.0004.02
N/A
Storm water Permitting and Pollution Prevention Support
Drainage Area Narrative
Dan River Steam Station
AMEC was asked to aid Duke in evaluating and describing sources of storm water inflow and
discharge at the Dan River Steam Station. AMEC has been working with Duke to evaluate
these sources and develop options for diversion away from the existing ash basin. The
following descriptions serve to further narrate the existing and future defined storm water
outfalls for the Dan River Steam Station site and the existing precautionary measures in each
drainage area.
Service water Settling pond Overflow - Former NPDES 004
o Discharge Structure:
120 -inch diameter CMP
o Location:
Adjacent to Powerhouse Structure
o Drainage area:
160+ acres
o Area Description:
This outfall receives waters from currently identified
stormwater outfalls, in addition to stormwater from a larger
upstream watershed from various other property owners.
o Explanation:
This area was in the past identified as a stormwater or
NPDES outfall but lack of presence of wastewater and the
location of identified outfalls upstream, plus status as a
Water of the State renders this location no longer a
stormwater outfall.
• Combined Cycle SWO02
o Discharge Structure:
o Location:
o Drainage area:
o Area Description:
o Explanation:
AMEC
Environment 8 Infrastructure
2801 Yorkmont Road, Suite 100
Charlotte, North Carolina 28208 USA
Tel (704) 357-8600
Fax (704) 357-8638
amec.com
36 -inch diameter RCP
Southeast of Combined Cycle Station
18.02 acres
This outfall conveys storm water flows generated from the
north eastern corner of the Combined Cycle Station, which
includes the northern 2/3 of the cooling tower, the two
chiller buildings, the chiller PDC, and the 1000 gallon
diesel and 500 gal kerosene storage tanks and their
associated tanker unloading area.
This area drains into the former SW 007, which is the
grouted 48"pipe. This area is not discharging stormwater to
the Dan River. Currently flows are pumped into the
Secondary Ash Basin (NPDES treatment to NPDES-002)
due to the presence of ash in the area above the grouted
48 -inch pipe inlet. Once the area has been restored, flows
Storm Water Outfall Narratives 9/15/14
Dan River Steam Station AMEC Project No.: 6226140004
are proposed to be pumped to Future SW009, rendering
sampling at the current Combined Cycle SW002 point
unnecessary.
Former NPDES Outfall 009/ former Dan River Steam Station SW 005
o Discharge Structure:
Concrete ditch
o Location:
Southeast of Combined Cycle Station and adjacent to
south end of Primary Ash Basin dike
o Drainage area:
10.5 acres
o Area Description:
This outfall conveys storm water flows generated from an
area south of the former combustion turbine area. The
area also includes a portion of the existing Primary Ash
Basin dike.
o Explanation:
This area is currently discharging stormwater along with
some seepage, and stormwater runoff from most of the
switch yard adjacent to the Steam Station. The switchyard
runoff is processed through an oil trap tank and the water
discharges through this outfall. The upgradient area is
proposed to be pumped to future stormwater outfall
SW009 once the outfall is approved. The area draining
immediately adjacent to the Primary Ash Basin dike and
the discharge from the oil trap tank is proposed to continue
on as an NPDES outfall location.
Storm Water Outfall SW001
o Discharge Structure:
48 -inch diameter RCP
o Location:
South of Combined Cycle Station
o Drainage area:
17.42 acres
o Area Description:
This outfall conveys the majority of storm water flows
generated from the Combined Cycle Station. Areas
include the Substation, Admin building, Generator and
Steam Turbine buildings, Clarifier, Clarifier Filters, Filter
Press and 1/3 of the cooling tower.
o Material Storage/Controls:
Chemical and Fuel/Oil storage details can be found on the
existing SWPPP document for the Combined Cycle Station
and accompanying Figure 2. Secondary containment is
provided for all chemical and fuel/oil storage. Additionally,
protocols are in place to manage storm water accumulation
in open air secondary containment areas. Valves in these
areas remain in the closed position until criteria are met to
release accumulated storm water into the drainage system.
• Storm Water Outfall SW003
o Discharge Structure: 3 12 -inch diameter steel culverts
o Location: West of the steam station powerhouse building
o Drainage area: 1.02 acres
Storm Water Outfall Narratives
Dan River Steam Station
9/15/14
AMEC Project No.: 6226140004
Storm Water Outfall SW003, cont'd
o Area Description: This outfall conveys flows from the laydown yard and
storage area to the west of the steam station powerhouse
building. All flow in the drainage area flows overland to a
ditch leading to the outfall. Drainage area is gravel and
grassed.
o Material Storage/Controls:
Spare equipment, parts, steel, iron, cable, and
miscellaneous supplies are stored in the large, relatively
flat gravel area. Some fabrication work may also be
performed in the area associated with the steam station
decommissioning effort. Equipment and supplies generally
do not contain liquid.
Storm Water Outfall SWO04
o Discharge Structure: 20 -inch diameter CMP culvert
o Location: West of the steam station powerhouse building
o Drainage area: 2.38 acres
o Area Description: This outfall conveys flows from the laydown yard and
storage area to the west of the steam station powerhouse
building between the warehouse storage racks and the
maintenance building. Flows in the storage area flow
overland to a ditch leading to the outfall. Area also
includes the oil storage building. Drainage area is gravel
and grassed with some covered roofs.
o Material Storage/Controls:
Oil storage area drains to a 200 gallon sump. Drums of
chemicals, cleaners, batteries, oils, and lubricants were
stored here during plant operation.
Spare equipment, parts, steel, iron, cable, and
miscellaneous supplies are stored in the relatively flat
gravel area. Some fabrication work may also be
performed in the area associated with the steam station
decommissioning effort. Equipment and supplies stored in
the laydown area generally do not contain liquid.
Storm Water Outfall SWO05
o Discharge Structure:
12 -inch diameter CMP culvert
o Location:
West of the steam station powerhouse
o Drainage area:
0.07 acres
o Area Description:
This outfall conveys overland flows travel/working area on
the west side of the steam station powerhouse.
o Material Storage/Controls:
No appreciable material storage is currently underway in
this area. The area will be impacted in the future by
temporary laydown and staging of materials during the
decommissioning project.
Storm Water Outfall Narratives
Dan River Steam Station
9/15/14
AMEC Project No.: 6226140004
Storm Water Outfall SW006
o Discharge Structure:
8 -inch diameter CMP culvert
o Location:
West of the steam station powerhouse adjacent to the
miscellaneous supplies are stored in the relatively flat
powerhouse building
o Drainage area:
0.33 acres
o Area Description:
This outfall conveys overland flows from the travel/working
decommissioning effort. Equipment and supplies stored in
area on the west side of the steam station powerhouse.
o Material Storage/Controls:
Storm Water Outfall SW008
No appreciable material storage is currently underway in
o Discharge Structure:
this area. The area will be impacted in the future by
o Location:
temporary laydown and staging of materials during the
o Drainage area:
decommissioning project.
• Storm Water Outfall SW007
o Discharge Structure: Drainage feature/ditch outfall to service water settling pond
o Location: North of Combined Cycle Station outfall
o Drainage area: 21.12 acres
o Area Description: This outfall conveys overland flows from the construction
storage, parking and laydown area and a much larger
wooded area on the west side of the combined cycle
station.
o Material Storage/Controls:
No appreciable material storage is currently underway in
this area. Spare equipment, parts, steel, iron, cable, and
miscellaneous supplies are stored in the relatively flat
gravel area. Some fabrication work or stockpiling may also
be performed in the area associated with the steam station
decommissioning effort. Equipment and supplies stored in
the laydown area generally do not contain liquid.
Storm Water Outfall SW008
o Discharge Structure:
Drainage feature/ditch outfall to service water settling pond
o Location:
North of Combined Cycle Station outfall
o Drainage area:
8.46 acres
o Area Description:
This outfall conveys overland flows from the construction
storage, parking and laydown area and a much larger
wooded area on the west side of the combined cycle
station.
o Material Storage/Controls:
No appreciable material storage is currently underway in
this area. Spare equipment, parts, steel, iron, cable, and
miscellaneous supplies are stored in the relatively flat
gravel area. Some fabrication work or stockpiling may also
be performed in the area associated with the steam station
decommissioning effort. Equipment and supplies stored in
the laydown area generally do not contain liquid.
4
Storm Water Outfall Narratives
Dan River Steam Station
9/15/14
AMEC Project No.: 6226140004
Future Storm Water Outfall SW009
o Discharge Structure: 6-8 inch diameter HDPE pipe from pump discharge
o Location: Service Water Settling Pond south of SW002
o Drainage area: 45.0 acres
o Area Description: This outfall will convey noncontact storm water flows from
drainage areas DA -A, DA -B, and DA -C by pump to the
service water settling pond. Areas will be discharged only
after contact water generating sources have been removed
from the areas. Currently these flows are pumped to the
primary ash pond for treatment.
o Material Storage/Controls:
No appreciable material storage is planned for these
areas.
Future Storm Water Outfall
SW010
o Discharge Structure:
6-8 inch diameter HDPE pipe from pump discharge
o Location:
Service Water Settling Pond south of SW002
o Drainage area:
77.8 acres
o Area Description:
This outfall will convey noncontact storm water flows from
drainage areas DA -D, DA -E, and DA -F by pump to the
north side of the secondary ash pond dike. Areas will be
discharged only after contact water generating sources
have been removed from the areas. Currently these flows
are pumped or discharged by gravity to the secondary ash
pond for treatment. This area includes the existing dry ash
stacks. Construction in this area that would generate
potential contact water will be managed to discharge to the
secondary ash pond for treatment.
o Material Storage/Controls:
No appreciable material storage is planned for these
areas. However, future construction in the area of the ash
stacks may result in generation of contact water which will
be discharged to the secondary ash basin, as is the current
protocol.