20150610 Ver 3_More Info Received_20170810

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ENERGY
Mr. David E. Bailey August 11, 2017
R-gaistury Project Manag-r
U.S. A, my Carps of Engineers
Raleigh Regulatory Field Office
-jaa-i Heritage Trade Drive, Suite 105
Wake Forst, North Carolina 27587
RE: ResDonse to Reuuest for Additional Information
Action J13: SAVV-L015-01Jul
Dan Rl.0 Stam. Station Sturm....atzr Di.a,-.tun Prulact and Assaciat.-d
Projects
Rockingham County: North Carolina
Dear Mr. Bailey:
Doke Energy, in consultation with Amec Foster Wheeler Environment & Infrastructare,
Inc., submiuea a stannam permit application to the Raleigh Regulatory Field Office of
the U.S. Army Corps of Enginzers (USACE) f, -,r isaaancz of Sartiun 404 Individual
Permit fur the Dan River Sham Station Stormvvater Diversion Project and Associated
Projects at the Dan River Steam Station in Eden, Rockingham County. The USACE
advertised the project by public notice on May iz, c0 i i. Comments in response to the
notice were received by three state agencies. The three agencies that provided
ruapum,zz; to the PabGc Nutica are: North Carolina Department of Natural and Cultural
Rasuurces (NCDNCR) - State Histoj]c PresGFvatiun Offcu (SHPO), North Caroli,.a
Wildlife Resources Cummissiun (NCWRC), and North Caralina Division of Water
Resources tMCDvvR). Responses to the requests ror autlitional iniormation antlror
cummGnts from these thruz ag%n;.ias a lm- presented bale...
Sobsegaent to yoor review of the application and sapporting ducaments, you presented
two requests ror aatlitionai inrormation in correspontlence Cate -0 .July «, cu i r, to Dane
Energy and the attention of Mr. Steve Cahoon. These requests were made to assure
compliance with the February 6, 1980, memorandum of agraemant (MOA) between the
Department of the Army (DA) and the U.S. Environmental Protection Ageilay (EPA)
(Determination of Mitigation ander the Clean Water Act Section 404(b)(1) Guidelines).
As enumerated herein for discussion purposes, these items and respective responses
are przaantod balu...vith requested rnaturiala ancl;,aad fur the USACE to re.ie... A third
item related to the DA - EPA MOA vvas also pruvidad by yuo, as regarding appropriate
and practicable steps to minimize losses of waters of the U.S. This third item is included
1lerein as acRnowletlgement Dy Dane Energy.
In addition to the above items in your RAI, you rogoestad information affecting the
temporary stream crossings authorized ander SAW -2016-00331. A response to your
request is inclutleo Herein.
[NCDNCR - SAPO
A rusp;,nsa to the Public Nutice, in conizspundance dated Junz 8, 2017, v.as pruvidad
by Ms. Renee Gledhill -Earley (for Ms. Ramona Barton, Dirc-rtur of Division of Historical

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EIQERGY-
Resources) to the 05HCE Raleigh Regulatory Fiela vmce ans the attention of RIr. Davis
Bailey. The SHPO did 4nct have any zinuatiuna regarding th% pr:,tzued pru;uct as
pre3ented in the Public Notice. A review of the project was conducted and SHPO wa3
aware of no hibtoric resou, cea which would be affected by the project. The SHPO had
no comment on the project as propo5ea.
NCWRC
A reatzmae to the Public N-Wtice, in corre3pondamu.- dated Jane 12, 2017, ..ab provided
by M5. Olivia Munzer, We5tarn Piedmont Coordinator, Habitat Conservation Program, to
Mr. Richard Harmon, Amec Foster Wheeler Environment & lnfra5traotare, Inc. The
NCWRC has no ohjection to the project, 15W oneres recommenaaduns to minimize
impacts to aquatic and tarroutrial ..ildlifa re3uurcuu. A5 anarnarated humin fu. diacwaaivn
parpu3e3, thc3a rucummendation5 and the respective reaponae5 are presented bola...
Recommendation 1
Daz to the pre3anca of protected apeciaa in the Dan R;ver, en3are off -Site eurmwater
does not contact other contaminated water or coal combastiun ,c5idoe from the site and
is routed around the site. All discharges into the Dan River or its tributaries should
comply with MPGEa permit requirements.
Reammoo
Ida contact water will he aischargea into waters of the O.S. iwedanas ane streams);
therefore, the water quality of du..natf oam reccl.iny r.'atcnz, spucifically the Dani River,
will nut be impaired. Spe4ifically, separation will be provided between wate, that has
contacted coal combostion r~sidae material (contact water) and water that has not
contacted coal comba5don re5iaue material anon -contact water), thereoy preventing
opportunities for the degradation of the aquatic. V-Zuayutern, including protected species
in the Dan River.
Under the stormwater diversion pomp -around alternative, Pipe Line 1 will convey non -
contact water to a proposes MPDES outfall. Specifically, Pipe line -i will consist of a
pore y and papa 3yatum that ..III cunvay nun-cuntaut vvoter from the Upland Flo.. Area
(UFA) to propu5ed Sturmwater NPDES Outfall SW 010. Prupo5ed Outfall SW 010 will be
located alv„g the northern edge of the p,oputty. Please note that Outfall SW -010 is in
5vv Permit as a tatare oattall. Hll aischarges into the Gan River or its
tributaries shall comply with NPDES m4mirarnanta.
Rcw„imendaCun 2
Culverts should be designed to provide aquatic life passage. Culverts or pipes should
be buried at Icast unc fuut or 20% of their al,.e bEluvv the natural streambad
(measured from the natural thalweg depth). Aquatic life passage should be assored
during low flow or drought conditions. mny riprap a5ed 5hoold not interfere with
aquatic life movement during low flow.
RCSpunsG
2

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ENERGY.,�
Culvert sizing and design fur the d:,.,nstnrarn cruising of the Dan River (DR) 131 Prujact
have been r7ovi5ed tti, include an addition 48 -inch calvCrt and provide sabmargence of
the culvert 12 -inches below the natural stream bed to allow for aquatic life passage.
Riprap or stone use is dmites to ift roaa rill itself ant] is not anticipated to interfere with
aquatic life movement.
Recurnmendatilun 3
Dative vegetation and bioengineer, -,-.d structarua should bx aaed for stream
stabilization where poasibla. Riprap used fur atr�=am bank stabilization shuald be
limited to the at, earn bank below the high-water mark, and vegetation should be
abed for stabilization above the high-water marK. Cong-term stalliiizadon can Me
accomplished using native plants such as red maple, black willow, sycamuru, river
birch, ailky dug..zod, and ether native wwdy species. Riprap should not be placEd
in the stream bed.
Response
The DR 134 Project will entail stnrambank stabilization for a perennial stream located
along the eastern boundary of the Dan River Steam Station near its confluence with the
Dan River. H portion or the western streamManR is erasing with some undercutting
occurring along the toe of the bank. Spucifivally, the arta of stivarnbsnk instability
occurs batww-en two colverted road crossings. It is along this area of instability that rip -
rap will be placed to armor the bank to prevent farther motion and stabilize the
streambank. The DR 13z; Project wil, result in an impact or i oU linear reef to a perennial
stream from the placement of riprap below the Ordinary High Water Mark (OHWM). No
ripr ap ..ill be plauud in the stream bid.
The permit applicant understands the NCWRC recommendation regart]ing the
installation or native plant species and bioengineered structures for long-term stream
stabil6atiun fur thv- prupused rrujact. V-getatiun orad for ground atabilizatiun fur the DR
134 Prujact shall be established above the OHWM.
Recommendation z;
RW—sead diatu,bed areas with sped mixta,'as that are benetiuial t�, wildlif6. Avoid
fescue -basad mixtures because fescue is invasive and p, Ovide* little benefit to
wildlife. Using native species instead of ornamentals shoals reaace the nee0 ror
water, rertilizers, ant] pesticides. Further information and free technical guidance
from NCWRC is available upon request.
Rebpanbe
Thu plant mixes and swecificatiuns for both tumpurary and permanent aaading for the
project work areas are based On standard and appropriate horticultural guidelines fur
seeding constraction sites. However, the recommendations provided by the NCWRC will
De taRen into consitleration.

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Recommendation 5
Sediment and erosion control measu,es shoold ase advanced methods and installed
prior to any lana-aistarRing activity. i he use of biodegradable and wildlife -friendly
sediment and eruzicn Central du.icus Is strongly reLommundud. Silt fan%ing, fiber moll
and/or other prudacts should haves loose-vvaave nutting that is made of natural fiber
materials with movable joints between the vertical and horizontal twines. Silt fencing that
has been reinforced with plastic or metal mesR snoaid be avoided as it impedes Me
movement of terrestrial ..ildlifu speLius. Ex=23ive silt and audirnurit I7,ad3 Lan havu
datrimuntal uffa,-,t3 un aquatic re3aarce5 including destruutiun of spawning habitat,
saffocatiun of Eggs, and clogging of gills.
Response
All davulupmunt pry-jects in North Carolina that disturb an acre or greater of land require
an approved Ersiun & Sediment Control Plan. E&Si-, Plans most Be prddocen
in accordance with the North Carolina Erosion and Sediment Control Planning and
Dealyn Manual, dated May 2013. Thio manual incladea beat management pract,cos
(BMPs) fur mduc;ng urosion and sedimentation daring constraction. This requires proper
site preparation techniques, sarface stabilization, runoff control measares, diffuse flow
iRroagR the riparian aairer, inim ant] outlet protection, and stream protection.
Rockingham C;,unry usua thi3 nmanaml v.hem directing developers daring nuv.
development ur redevelopment that UACaads one acre. As Rockingham County ;s nut
NPDES Phase II nor is the watershed in a regulated community, it has no post -
construction sail ana erosion or stormwater control oQligations. RocRingham County
relies upon the North Carolina Department of Envirunmuntal Qualiry (NCDEQ) Winatun-
Salem Regional Office t -u aversue and unfarzx their federal so;l and urusian cuntrul
requirements for new con5traction.
Project activities for the Dan River Steam Station Stormwater Diversion Project and
A330ciatud Prejuct3 will b -W ccndact-od in a manner tu minimize the putential far erasion
and sedimentatio,,. Sediment and eros;un cont, al measores shall be installed prior to
land-distarbing activities in accordance with an approved EBSC Plan. The EBSC Plan
inclat]es re -seeding scReaales ana metRods to minimize sediment discharge from the
site. The recommendatiuma provided by the NCWRC will bu taken ;ntu considertivn.
NCDWR
A response to the Public Notice, in correspondence dated June 1, 2017, was provided
by Ms. Sae Homewood, Winston-Salem Regional Office, to Doke Energy and the
attention of Mr. Steve Woon. As enumerated herein Tor discussion purposes, tRese
items aind the m3p1-Uctivu reapun3es are prz3unt,-.d buluw (v.ith attachmenta).
Item Number 1
This project includes a ruvisium to ;mF,aCts Proviuualy apr,ruved bre the Divi3ivn un May
12, 2016 (DWR#2016-0156v2). Thusu imparts were for an actress road for the Da„
River Scarp Repair and were app, oved as temporary impacts. The carrent application
for an Individual Permit requests that tRese impacts Ve approvea as permanent impacts.

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ENERGY
The original i-wvlaw by the Divi5iun was based on temporary impaLts and therefore the
Divisio„ rgaires a more detailed analysis of the purpose and need fur permanent
impacts a5 well as a more detaiien anaiysis of avoitiance anti minimization measures. In
aut1hion, this project will be placed on hold until a cumr,liamce in apectium of thlaZ
uulv1rt3 has been Lcndocted. [15A NCAC 02H .0506(f) and (g)]
Response
The turnpurnry placement of a culvert at each of two road crossings of Strcam 3
(p7arannial stream) at the Dan River Steam Station was previoo,ly app, oved by the
NCDWR (DWR#2016-0156v2) and the USACE (Action IC SHW-A i'o-Uti3o i). i Me
calve"e roati crossings were created to facilitate vehicle and equipment access to the
northern shuralin e of the Dan River. A=Ez3 to the Dan River shuraline 6 nacE3aary fur
37.arp repair, a5 needed, daring the clo5arC of the ash basins and the transport of coal
ash from the station via a barge loadoat area. The pending Section 40z; Individual Permit
application for tie Dan miver Steam station otormwater Diversion Project and
associated Projucts (Artium ID: SAW -2015-01381) pmposod that buth colvert3 wwold not
be r�movad and the strum would not be uesturcd (via contour reshaping, etc.) to pre=
impact conditions. The impact to Stream 3 from the installation of the two culveRs
cumpi iced 86 linear feet; i.e., zF3 linear reef of impact iar me northern roati crossing ana
zF.3 linear feet of impact for the southern road croaJmg. After farther uvaluatiu� � of thu
pruFuaed action, the parmit applicant and protGLt engineer have made adjustments to
the project design that will mini,, it -e impacts to Stredm 3. Specifically, the culvert at the
northern road uio55ing has been removed. i Me northern roati crossing, as a proposes
permanent feature, will no longer exist. This action has resulted in a reduction in impacts
to Stream 3 of 43 linear feet. Huvzvar, the impact (43 linear feat) to the auethern road
crossing of Strum 3 will remain ander the pending Section 404 Individual Pei mit
applicatiun; i.e., the southern road trussing will be a permanent feature.
Table 1 below includes the afuJarnua tiuFzd Lhanye in pr;—,pm ud impacts to Strum 3.
Specifically, the impacts to Strea,,, 3 from the placement of the two zulvert5 at the
northern and southern road crsbingb have decreased from 86 linear feet to 43 linear
feet with the removal of the culvert at the northern roasa crossing.
Table 1. Prupoaad impacts to juriadiutional vvetlanda, atfcoma, and duedge basin
fur the Sturmwater Diversion Project, DR 134 Project, DR 131 Projeut, 36 -
Inch Pipe Closure Project_ and 48 -Inch Pipe Closure Project. Dan River
steam ;*tatiun, Rucr<inallam Cuunty, rmorlil Carolina.
Resource Type
Proposed Impacts
Project Component Wetlands Streams
- (acres)linear feet
Stormwater Diversion Project
Wetland A WSA-3 0.19 -
Wetland D CIFH 0.16 -
Wetland F UFA 0.06 -

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Access via the suothern culveffe-d stream crossing isiream o roan crossings to Me
northern shoreline of the Dan River is necessary for scarp repair. Purrnan unt uZzaaa ria
the ouuthu,-n cruising is nacassary to facilitate fotarc maintEnanLe �f the Primary and
Secondary Ash Basins embankme„ts along the Dan River. Such maintana„ce would
inclade futu,e scarp repair. The southern road crossing will be maintained for future
necessity anti emergency access to the shoreline areas along the Dan River.
If the wether„ road trussing is net permanently established (i.e., if the culvert is
removed and re-contoaring is completed), future scarp repairs, as they arise, would
necessitate tie reinstallation of LI1e culvert- Such continued future impacts to the stream
channel would be Carminative.
The installation is to zopport minimization of erosion along the Dan River- Use of ruck
instead or sail to improve installation and the improvement of the existing temporary
crossing (via a change tv purmiament crusuimg) arc prupu3ed. Thuzu aitiuuria ..III faillltaate
minimi=atiun of impacts, prescunt and future.
S
Proposed Impacm
Resource type
Project Component-
- -
Wetlands Screams
acres linear feet
Stream 1
UFA
- _ 393
Dredge Basin
WSA-1
1.89 -
Total
i.;9 393
DR 134 Project (includes prior work activities)
Stream 3 Bank Stabilization -
-1s0
Stream 3 ulvert Installation (March 2016) - 43
DR 131 Project
Stream 3 Culvert Pipe Extension - 15
Total DR 134 and DR 131 (Stream 3) 188
36 -Inch Pipe Closure Project (previously permitted)
T Pipe Closure with
Wetland H Overflooding (includes fill for 0.098 -
cofferdam
Stream 4
Pipe Closure with -
65
Overfloodin
48 -Inch Pipe Closure Project (previously permitted)
Wetlands
Pipe Closure with
0.407
Overfloodin
Streams
Wipe [:losure with
-
448
Overfloodin
Access via the suothern culveffe-d stream crossing isiream o roan crossings to Me
northern shoreline of the Dan River is necessary for scarp repair. Purrnan unt uZzaaa ria
the ouuthu,-n cruising is nacassary to facilitate fotarc maintEnanLe �f the Primary and
Secondary Ash Basins embankme„ts along the Dan River. Such maintana„ce would
inclade futu,e scarp repair. The southern road crossing will be maintained for future
necessity anti emergency access to the shoreline areas along the Dan River.
If the wether„ road trussing is net permanently established (i.e., if the culvert is
removed and re-contoaring is completed), future scarp repairs, as they arise, would
necessitate tie reinstallation of LI1e culvert- Such continued future impacts to the stream
channel would be Carminative.
The installation is to zopport minimization of erosion along the Dan River- Use of ruck
instead or sail to improve installation and the improvement of the existing temporary
crossing (via a change tv purmiament crusuimg) arc prupu3ed. Thuzu aitiuuria ..III faillltaate
minimi=atiun of impacts, prescunt and future.
S

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Item Number 2
Your application indicates drat 130 linear Teel of stream 5iaBilizadon will occur at location
DR -134 however Plan Sheet DR -134 Section Detail, Figalu 02 ahu..s riprap ahadiong
throughout the entire channel bad. Please clarify whether riprap will be extended
throoghuot the channel bed.
Response
Riprap will be placed in the channel bed only as required to provide a working platform.
Ideally, the riprap will be placed from the sop of the stream channel ana the only
encroachment into the stream will be to extend the slope tie-in at the base of the
channel.
Item Number 3
As requaatzd in the p iapplication, plUaaa provide a detailed analysis of the volucity
uApGc,ted at outfall SW -010, the riprap pad specifications and details, and an analysis of
the impact this additional flow and velocity may have on wetlands that are present
immediately downslope of this area.
REauunsa
Outfall SW -010 is in SW Permit (NCS0005rc) as a future outfail. l he pealt flow a -E
Ounall 5vv-010 is anticipated to be about 0.9 cubic feet per second (ds) with a velocity
of abuut 4.5 fact per secund (fps). The anticipated flu.v rate and velocity is nominal az
evidenced by the fart that the calculated values (0.9 cfs and 4.5 fps) are less than the
minimum values shown on the riprap apron sizing nomograph. A riprap apron will be
area to Tanner dissipaie Bows prior to discharge to the receiving land area. i fie selected
ripraw apru n dirnanoiun9 uxuacd the minim.am rruquuirud du9lgn dim7.n9iun9. BaScd un
these uunsiderations, there are no anticipated negative impacts to the receiving drainage
pathway, including wetlands that are located downgradient of the riprap apron. Note: the
nearest wetland area to the proposed riprap apron is locates more than 50-reet Trom toe
proposed structure.
The attached document Riprap Area Calculatiot, provides details on the analysis,
including objective, method, calculations, discussion, and references.
DA - EPA MOA Item
a. Parmits for work within wutlanda -Wr wither special aquatic aitea are available only
if the proposed work is the least environmentally damaging, p, acticable
alternative. Please fornish information regarding other alternatives, inulading
uplana alternatives, to the worn for which you have applied ant] proviae
ja5tificativn that y.,ur iGIGctud plan 1;2 thu last damaging to .Yater or w-Vtland
amus.

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�. EMERGY
1) Your permit application includes three alternatives fog the Stormwater
Diverslun Project, including using a 400 gallon per minute (gpm) Pump
around, a zi:9,000 gpm High -volumetric Flow Rate Pump-arouna, ant] Gravity
flovv. Huvvcvur, during our February 17, 2017, pre-applicaticn meeting rvv
discussed including a fourth alternative using a reasunable "in-between" flow
rate pomp -grand alternative. The goal of this alternative would be to evaluate
any reauctions in over -noosing impacts to wetlanas ana streams proposes
a3auciatad with the upland flu., arca (UFA). Please iriuludu this altumat;vu as
di3co3aed, specifically with regard to practicability per 40 CFR § 230.10a.
Response
The altcrnativa3 analyzea wcrc p;rfu-rm=d based on the valcalated runoff from the 25 -
year, 24 -hoar design storm event. The pumping rate for the High -Volumetric Flow Rat=
(49,000 gallons per minute [gpm]) Fump-around Hlternative was obtained by convening
the peak runoff flow rate during the 25 -year, 24-hour storm from cubic feet per second
(cfs) t� gpm to prevent mandation of the stream and wctl-and complex vvithin the Upland
Flow Area (UFA). The impacts for the Pomp -around Alternative (preferred alternative)
were conservatively obtained by calculating the total runoff volume from the 25 -year, 2Zr-
nour storm event ana comparing to the stage -storage curve for the UFA to develop an
estimated water aurFce elevation (inundation alevat;on), and then comparing the langth
of stream and area of wetland within the UFA lower than the inundation elevation. The
calculated impacts for the Pomp -around Alternative are conservative because the effects
or pumping were not consiserea; Mereiore, the stream ana wetlant] impacts for the
Pump -around Alternative are i-aumJtivc to pumping rte. We prupusa oainy the
zunsenrative estimata of potential impacts in the event that human arror or unachanical
failure pieventb pumping daring the design storm. The preferred pump rate was listed as
zF00 gpm in the Individual Permit applicaticn pacKage eases on conceptual design. i he
actual pump rate will be determined during final design to dewater the UFA without
causing instability to the pruposcd divider berm embankment.
DA - EPA MOA Item "b"
b. It is nccZ-ssary for you to have taken all appropriate and prnctivablu ateps to
minimize losaea of waters of the U.S., including wetlands. Please indicate all that
you have done, especially regarding development and modification of plana and
proposes construction tecnniques, to minimize adverse impacts. specifically:
1) Your permit application includes avoidance and minimization information and is
generally sufficient for continued evaluation.
RE3wunse
The permit applicant acknowledges the above comment regarding appropriate and
practicasle steps taken to minimize losses of waters of the U.S. for the proposed project.
DA - EPA MOA Item "c"

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The MOA requires that appropriate and practicable mitigation will be requ;red for
all unavoidable adverse impacts remaining after Me applicant has employed all
appropriate and practicable minimization. Please indicate your plan to mitigate for
the projcctud, anavoidabl-0 1033 of watcr3 or vvetlandz or provide i„ furmatiun as to
the absence of any such appropriate a„d practicable measures.
i y Please provide the mitigation acceptance letter from the NC Division of Mitigation
SErviuu& (NCDMS). Plaas-= note that W=tland3 A and the Drudge Ba3in wretland
would both classify as Headwater Forest wetlands per the NC Wetland
Assessment Method (NCWAM) Dichotemoos Key, despite the downslope fills
oevelopet] as part or earlier aevelopment operations at the Dan River steam
Station. This determination wva3 made givEm that both of those .,etland 3ystEmaa
ocLur within natural topographic cranulations without stream3. The Ccrps
considers Headwate, Forst wetlands to fit the wetland mitigation credit
classification or Riparian, Ron-Riverine wedanas raver than Ikon-miparian
YYGtlpnd3. Plca3a clarity your ~wetland mitigation propo3al beaud on the above
Response
The permit applicant acknowledges the above comment regarding the classification of
Wetland A and the Drudge Bazin vvEtland a3 Headwater Foreat vvatland3 per the
NCWAM. The permit applicant also acknowledges the above recommendation by the
USACE to include these two Headwater Forest wetlands ander the wetland mitigation
credit classification of Riparian, Non-Riverine wetlands rather than Non -Riparian
vvatland3.
The permit applicant ;s in the press of obtaining the mitigation acceptance letter from
the MCDIOIzi. Hs soon as tie acceptance letter is receivet], it will Be rorwamet] to tMe
USACE. Pleaze note that the mitigation credit parcha3a vvill ruflert tho change to the
mitigation requirement3 for Stream 3 based an the reduction in impact3 to this feature
with the removal of the culvert at the northern road crossing (i.e., a decrease in Stream 3
impacts from els linear feet to zi3 linear feet. i aGle /_ presents the updated summary of
the anticipated mitigation costs for impacts to waters of the U.S. for the Dan River Steam
Station Stormwvatur Divcmion Project and a33ociated Prujact3.
Table 2. Mitigation costs for Impacts to waters of the U.S.. Stormwater Diversion
rroject, DR IszF Project, Dec 1,3_1 Project, s6 -Inch ripe Closure Project;
and 48 -Inch Pipe Claunru Pro'e:.t, Dan River Steam Station,
Rockiu,gham County, North Carolina.
NCDMS Fee Category
Riparian Wetland
Riparian Wetland
(Non-Riverine)
Features
Stormwater Diversion Project
Wetland D - NC WAM Medium Rating
Wetland F - NC WAM Low Rating
Weiland A - NC WAM Medium Rating
0.16 acre
0.06 acre
0.19 acre

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NCDMS Fee Category Featurn rroposed
Im aC1I�
Riparian Wedand Dredge Basin - NC WAM Low Rating 1.89 acre
(Non-Riverine)
Perennial Stream Stream 1 - NC SAM High Rating 393 linear feet
DR 134 Project (includes prior work activities)
Perennial Stream Stream 3 - Bank Stabilization 130 linear feet
Perennial Stream
Stream 3 - Culvert Installation (March 2016)
43 linear feet
Southern Road Crossing
DR 131 Project
Perennial Stream Stream 3 - Culvert Pipe Extension i 5 linear feet
36 -Inch Pipe Closure Project
Riparian Wetland
Wetland H - Pipe Closure with Overflooding
0.098 acre
Perennial Stream
Stream 4 - Pipe Closure with Overflooding
65 linear feet
48 -Inch Pipe Closure Project
Non -riparian Wetland Pipe Closure will vveMooaing
0.407 acre
448 linear feet
Pertnniol Steam Pipe Closure with Overflooding
All Projects Combined
Ree Category
i opal Impa= iNU1113Rla Caicumilonsj
Cosi
Riparian Wetland
0.508 acre
0.75 acre inc. X 2 mit. ratio X $40,580 unit cost
$60,870
Nan -riparian Wetland
0.407 acre
0.50 acre inc. X 2 mit. ratio X $26,631 unit cost
$26,631
Perennial Stream 1084 11 near feet
$656,400
g 1094 linear feet. X 2 mit. ratio X $300 unit cost
$825,061
Sum of All Costs
' Tvlol coat net ppb -ua lct By tFi� 05ACE
Tem ora Stream Cru3ain SAW -2016-00331
1) GivEn that une ur buth of the temporary stream crossings aathorit-ed ondvr
ShW-/_0 i'o-00,0j 1 Have experienced recent carnage noe to fligll TTow events,
and at least one of these crossings will be removed pending authorization of a
parman�nt cruo3ing, p6asa pruvid-V culvert pipe plan3/d;-=tail5 for these
crossings described as part of the DR 134 project. Note that, onless utherwise
justified, these permanent crossings mast abide by Nationwide Permit Regional
Condition 3.6 issued March 16, 2017. Further, it appears that Figure 02 "Dan
River Steam Station DR -131 PrujaLt Impact Area" due3 not comply vv;th
Regional Condition 3.6.1 as the pipe is pc, ched above the WAisting stream bed.
10

I- DUKE
v4, EAERGY
Lastly, given recent Might now events, please evaluate up-sizing the propose0
culvert pipe diamutur ur imcruaainy thu numb%r of cohort }yip -W3 placed at eaLh
crus3ing.
Response
Culvert aiming and dE3ign for the downsti earn creasing (soothGrn read cruasing) of the
DR 134 Project have been revised to include an addition 48 -inch culvert and provide
submergence of the culver-L c -inches 13elaw the natural stream DO to allow ror aquatic
Iffe passage. Riprap or stone use is limited to the road fill itself and is not anticipated to
inturf,ure with aquatic life movement. The r.vised dravving3 of the colvErt pips
plansldetalls are attached herein. Please note that the revised drawings are inzloded in
the engineering sheets for the DR 131 Project. The DR 131 Project entails work
associated with the southernmost road crossing. Specifically, the proposed action
will entail thU axtansiun of thU 3oothlrn culvert pipe downatraam to raise thi
Glevatiun of the crest of the southern road crossing (to provide a more purmaneilt
and stable approach for vehicles and equipment thiough the crossing). The existing
calveR at d1e noRnern road crossing nas Been removed. i Ile northern roa0 crossing, as
a proposed wcrmanant fcaturc, will mo lunger a.i3t and is nut shu.,n un the DR 131
Project ravi5ed drawings.
Thank you in advance ror your assistance with this project. If you Mave any questions or
need additional information, please contact me at telephone number [phone] or
cmall addre33 atava.cohuumOdukE-an�rny.cum.
Sincen=l
0101,
Steve Cahoon
Enclosures
Cc: Soa Humewood (WCDEQ DWR)
Cedric Rohl (Amec Foster Wheeler)
Josh Bell (Amec Foster Wheeler)
Richard Harmon (Amec Foster Wheeler)

� DUKE
r►, ENERGY
ATTACHMENTS
12

RIPRAP APRON CACCOQCTION

hiprap Apron Calculaiion
Duke Energy - Dan River Steam Station
Dan River stormwater Diversion
Calculation Tule:
Riprap Apron Calculation
summary:
t Re peaR flow at OUtTah zm-D t u is anticipatet) to Ce a5out u.ii cis will a velocity of anout ZF.a Leet per
second kips). The anticipated glow rate anO velocity is nominal as evidenced by the fact that the
calculated values (0.9 cfs and 4.5 fps) are less than the minimum values shown on the riprap apron
sizing nomograph. A riprap apron will be used to further dissipate flows prior to discharge to the
receiving land area. The selected riprap apron dimensions exceed the minimum required design
dimensions. Based on these considerations, there are no anticipated meg.tiva immpart. to ille receiving
arainage pathway, including weilanas ilia[ are locatela Downgratlient or the riprap apron.
l9oles:
Revision Cog:
No.
Description
Originator
Verifier
Technical Reviewer
00
Initial Submittal
/r+ �� "
U,-,{, �' ly+N k ►�
(t'�
F-eoric Hunt
;joMn carona
Mfg aoroan
Rmec Poster vvIleeier Project Mo. 7810-17-0895 1 0 3 1-7
6715117 (IniCul 505mitt-1) eme[ 1.
tost�.
wheeler

Riprap Hpron Caiculation Dan river wormwater Diversion
Duke Energy - Dan River Steam Station
The ob;aut4v of this calc.6tiun is to dlsiyn thl riprap apru , fur aturmwater diyursiun mumu l,tact
water pumped ilow to Outfall Svv-010.
IZE i HUD:
Thu riprap apr +n was daaign�d in azuurdam;u with the North Carling Erosion and Sudir..unt
Control Planning ana Design Manual.
VAEVuEA i WAS:
1.0 [. OIC0letE Ttvvv %vnditiouiz
Noncontaut aturmyvaW will be pumped to Ontf all SW -010 at an apprUAimats rata of 400 gpm
througfl a 6 -inch diameter pipe. The peak flow rate and velocity are shown in tfle following tal5le:
z.0 Ualculaie minimum requires riprap apron aimensions
The minimum required riprap apron dima..slono and riprap median partiuh dialloctar (d�.)) ..as
designed in accordance with Me NolIM Caroiina Erosion and Sediment Control Planning and
Design Manual [Ref. 11. The maAmum particle diameter (d....7) is 1.5 times the median particle
diameter (dso). The riprap aprun thicknass is 1.5 timas tho maximum parti%lo diamv-tar (d..--). The
minimum required riprap apron dimensions are shown in the following table:
Table 2: Min]; --urn Design Riprap
Apron Size
Table 1: C..le=lzt.d Flu- C.wditiun=
Downstream
Pumped
Pumped
Pipe
Pipe
Discharge Velociry
FIs -Rate
FIs -Rate
Pipe Df■mcz-r
Bio-ete.-
Area
at Pipe O.tlet
Igpmr
ids,
tin f Iftr
(fe,
lift/sl
400
0.89
6 0.5
0.196
4.54
z.0 Ualculaie minimum requires riprap apron aimensions
The minimum required riprap apron dima..slono and riprap median partiuh dialloctar (d�.)) ..as
designed in accordance with Me NolIM Caroiina Erosion and Sediment Control Planning and
Design Manual [Ref. 11. The maAmum particle diameter (d....7) is 1.5 times the median particle
diameter (dso). The riprap aprun thicknass is 1.5 timas tho maximum parti%lo diamv-tar (d..--). The
minimum required riprap apron dimensions are shown in the following table:
Table 2: Min]; --urn Design Riprap
Apron Size
Pomp=d
Downstream
Minim=-..MINIMEwr
0= Riprap
Miwi-am
Riprap
Ap =w
Minimum Minimum
W Idth .f Apr.
Pipe
size
sire
Thl■kw.ee
Minimum d-
Minimum d-
d..
Flow
t7ia-
LengtR or
epsream
rlewnstre.m.
Riprap Size
Riprap Size
Riprap Riprap
Rat■
v
Apra
Width .f Apr.:
Wldth _f Apruw
Sl;. Thi=kw=ss
{cps)
tinj
IT.}
(W-0
(rt)
In)
(Iw}
in) {ft)
a
v
Z...
0.5
e.2
2.4
3.6 0.5
3.0 Duthie selected riprap aptun dimensions
The riprap apron dimensions were selected to be greater than the minimum design riprap apron
sizing criteria as shown in the following table:
-blc a: ulucrud Riprop -pron Size
Length of
Upstream
Downstream
NCDOTRiprap
0= Riprap
o,, . 1prap
Riprap
Ap =w
Width .f Apimn
W Idth .f Apr.
Cl-=-
size
sire
Thl■kw.ee
(ft/
Ift,
(ft)
IRer. 111
in
in
01)
io
:e
v
OZ
Rmec Foster vvneeler Project Mo. 1010-17-x895 2 of 3 N
611511 I (I.A1.1 Ssornittul) amec z
fvet.r
m ieeter

Rip.ap Kp. r; Calculation Dan River Stormwater Diversion
Duke Energy — Dan River Steam Station
DISU05SIUM:
The peak flow at Outfall SW -010 is anticipated to be about 0.9 of5 with a velocity of about 4.5 feet
per 5ecund (fps). The anticipated flaw rate and velocity is nominal as evidenced by the face that
the calculated values jO.y cis and zr.o tpst are less man ine minimum values shown on the riprap
apron sizing nomograph. A riprap apron will ba used to further diasipate flo..s prior to di3oharge
t -U the receiving land area. The ,elacted r;prap apron dimensions eAoeed the minimum regoird
design dimensions. Based on these considerations- there are iia anticipated negative impacts to
the receiving drainage pathway, including wedantls Mat are lacatet7 aawngraOient or tOe riprap
apron.
REFERENCES:
I , Mortll Carolina Department of Environment and Natural Resources, "Erosion and
Sediment Cuntrol Planning and Design Manual", Revised May 2013.
2. "Standard Specification for Ruads and Stroctores", North Carolina Department of
TranspaRation, maleigM, January z'v i e.
Rmec Foster wheeler Project No. MU-17.08tin a 013 17
6715117 (I .i W 5a6mittal) am2C
j vamr
wneeler

REFEREWX 1
Borth Carolina Department of Environment and Natural Resourcus, "Erosion and Sediment
Control Planning and Design Mammal", RG,Alsad May 2013.

8.06
Appendices
Riprap (large stones of various sizes) is oven uses to prevent erosion at [rte ends
OI Vol -orb aRa etne.- pipe contIM. ,. It won-ertz; I�ls6-:elee:[�, eeRveR[ratca
pipe ny- rata Ie--:vlvelty, vyem .Ran. -.el no—... biome AwJa ow z;<<eR aRa Inc
to rmicat leee::iRb anum-el., ffflM crezi:v.. vae.,va n7 FR=HM
pipe c -it Riyrup voile[ 3Rv43 rnc.t all rc;n`1Fvmcrft h-.
t-,-1.* . .51—a— m ... U.a1, 11.11r1Jl..b.I:3.<1:..,.31,-1...
be:c -1 ctnvaa u.e atlet 3t .etore3. In.
Ctnv11 yre5c7f.d I.-. tn13 3CctiuM 13..a..ptc11 r.vrn yiveeaoac,, 09.11 D, tn. 17b1JA
bo;I CvnacR..tio . berTlee. Vetlet ylbleetivn ;3 pro;:11.11 6, a Ic:cl ..prep of
30tT1WicRt I,;.btn .aMa Ill -C tv rvilfl v tiv- rC10vltlC3 [v Ra7.,.v317, 1CTc13.
❑e5iyjn t-,roceiJhre Tor i ne tollowin, proccusiv uses t -v sets ornesi,n cnrr,s: rig»re z 0iia is uses
Rira Outlet Ior minimum tail -acct Cv-.tiitiams, anti Figure a.uBD R,»�ilR»m t..ilwatrr
Riprap conditions.
Protection _
b[vt, 1. Uele.—:Re Inc i..1l-ale. aeyTR 11FUM CH -M..01 viI«r0e[e.-i3Ge3 Belo-- the
pipv volicl tv-. me nv..i5R e.-.p.city vI ine pipe, it IRe L.Il-tiler aey[n i3 Iv;3
in... n..li iRe amid pip, a:..rmeier, it :.. ck--ined rninl 0- [.,Il :..ler ev;alidvm.
I1 it !3 src.aer TR..R nuirine piyv 11:11 -el,.-, it :z eI..3 :nod vv;-..Z14ivm.
ripc3 in -t v-.tici am[v --al. n"t ..res3 ::TR ny aenmen A -Tinel ..z ;---0mnen
to n -Tv a :IRI -O- Ia;l -.,ts eom11ltle:. nRlesa FllaDle nova ,tine creation-.
ane - vtnei , i.,c.
Step L. tsased on dte tailwater conditions tietermineti in step I, enter rigure
a.05a or rigure MIN, anti determine d, � riprap size anti minimum apron lengtn
(Co). i Re d,,, size is ine median stone size in a well -graded riprap apron.
Step 3. Vetermine apron width at the pipe outlet, the apron shape, and the
apron width at the outlet end from the same figure used in Step .L.
Step 4. Determine the maximum stone diameter:
dm_ = 1.5 x d50
Stcp S. im.rmiRv tn. apron trii.Kntas:
Aprflrl MLKRe.3 = l .b n 13max
btep U. Fit Inc .-ipr..p to tnc 3itc B, M-K:n, it 67.1 ter In. mtia.-" neem
lo. -.stn, C., from. rii;e.-c 5.0- or 5.055. C.,tena Inc prem r..rtnc:
ay -n,tre..rn Zna alvmb cnanu'ul DenR3 until 3t-SiEt., ;3 u„ere11. &ccp Inc
..p. -.R w 3t -mibnt .z, pv99:blc ..nb ..11sn It : !In tn. n--;; of tn.
MNK. N. -.J nCCC,9u:.7.1LSrlMcRt Dcna9 -•c..r Inc y;}.c vi3let ,a Mat tnc cRt u. -.cc
iiaty tn, i,C,Ivirlb 3tTC7.m !� ataawlbrlt.
Rc-. 12193 19.05.1

REFERENCE 2
"Standard Spaaifiaatlano for Roads and Stractore3", North Carul;na Dat,artmar d of
Transportation, Ralaigh, January 2012.

Section 1043
1 All sone shall meet the approval of the Engineer. While no specific gradation is required,
2 there shall be equal distribution of the various sizes of the stone within the required size
s range. ine size of an stone r.�rt;elc 77;11 ne tlatvlMiriva ny nRv,-ll.�.,b 4. Iaelb
4 dimension.
5 Stone or broken concrete for rip rap shall meet Table 1042-1 for the class and size
5 distri0ution.
TABLE 1042-1
ACCr r 1 AtrCL' iCmi l LK1A r VK Kir KAr Al\u S i Uri r, r VK EKV51Vii CUr4 i KVL
Class
Minimum
_ Required Stone Sizes, inches
Midrange
Maximum
A
L
"�
4
6
B
—
5
_
8
12
I
3
10
I /
2
9
_
14
23
I4o more man :).0% or ine material 5c ICziJ mm.-. inG
�;zo 3t,=t;i%63 „vr
8 no more than 10.0% of the material
can exceed the maximum size specified.
9 SEC.I IVIN 1643
10 AULYKEhA 1 E V KV1V1 %-KUSIIEli %-tJI'NL KE 1 E
I 1 10$J-1 GENE' KAL
12 Aggregate from crushed concrete is a recycled product made by crushing concrete obtained
13 from concrete truck clean out, demolition of existing concrete structures or pavement, or
IZF similar sources and transporlea from a crusning facility. it noes not incwae concrete
ID t,u:ciacntZ''nut..,t aanni�l:z�d, 6roKun or otherwise crushed in ,lace on the roadway.
16 The crushed material must meet all sources approval requirements described in Sections 1005
t r and iEft with the exception of the sodium sulfate test requirement. ueteterious materials
t5 snau not oe mo. a man.5,/a.
19 Sampling and acceptance for the determination of gradaction, LL and PI will be performed as
20 described in the Aggregate QC 'QA Program Manual and the ftggregaie Sampling Manual.
l i 194J -z AGG1cr:GA 1 E nASE COURSE
22 The material shall meet the ABC gradation. The LL of the material shall be raised 5 points to
L.] no more than .».
24 1043-3 AGGREGATE SHOULDER BORROW
25 The material shall meet Section 1019.
L6 104.3-4 CLLAIN COAKSL ACGiKLGArE FOR ASPHALT
27 The material shall meet the gradation of a standard size in Table 1005-1. Use of the material
28 shall be approved by the Engineer, and the mix shall meet all requirementu.
29 1043-5 CLEAN COARSE AGGREGATE FOR CONCRETE
30 The material shall meet the gradation of a standard size in Table 1005-1. Use of the material
j I is resirictea to fuss 6 concrete mixes omy. use of tele material snau Be approved Dy me
31- and the concrete shall meet all requirements.
33 5EC.IIVIN 1U44
34 5UUSUKVACE I)KAJIINAC.E IVLAIEMAL5
X) 1lJ$4-1 NU1suKAlix ritvr, AC:%Kt,i,A1 it
36 Subdrain fine aggregate shall meet No. 2S or 2MS in Table 1005-2.
10-62 NC:110T 2012 5ta.-Add speatm-tions

DR 131 PROJECT ENGINEERING DRAWINGS

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