NC0004774_Identification of New Discharges_20160503

D nergy Carolinas, LLC' I Plan for Identification of New Discharges
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Buck "Combined. Cycle SfaEion Ash Basin
REPORT VERIFICATION
Report Verification
PROJECT:.
GROUNDWATER MONITORING PROGRAM
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.BUCK COMBINED CYCLE STATION
ASH BASIN
NPDES PERMIT NC0004774
or
TITLE:
PLAN FORIDENTIFICATIONOF NEW DISCHARGES'
This document has been reviewed for accuracy and quality commensurate with the .intended
application..:
:::.. ...
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Prepared by:
Date:
j Checked by:
pate:
Approved by::.::
Date: :.:: .
�,....
Project Manager: Brooke.Ahrens, PE.:: . .
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Professional Engineer Seal:..
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HDR Engineering, Inc. of the Carolinas
440 South Church St., Sdite100
Charlotte, NC 28202.::
North :Carolina Engineering Firm Number F-0116

u Carolinas, LL har
Duke Energy C C I Plarrfor Identification of lVew;Disc
_ Buck Ctlmbined Cycle Station Ash B. ,ages
sin - 1-N
TABLE OF CONTENTS . ..
Table of Contents
Page ..
Report Verification ............. .............. ............. .................... ........:............ .. _ ...... I ...
Table of Contents .................................. ............ .. . i'
List of Figures....:.....:.:..::.......................:..:...................... ................. .
......:.. ..:........
Section 1 -Introduction ............... - .... .... .....1
3
.Section 2 = Site Description.....................: ................................... ......................... ............. 2.1 Plant Description
3
2.2 .... Ash Basin Description............. ...... . . ..............� .:....................:... ... 3
... 4
2.3 Permitted NPDES Wastewater and Stormwater Outfalls.......... :........................... :...
Section 3 - Site:Geology and Hydrogeolog
3.1 Site Geologic/Soil Framework ................ : .............................................................. :.:6
3.2 Site Hydrogeologic.Framework................... ........... .... •••••
8
Section 4,7: :Identification of: New:Discharges ..:...::::.:.:.
4.1 Purpose of Inspection..............
... .. ...
4.2 Seepage ................. ..:
.... 8
4.3 Area To Be Inspected for'New Discharges .............
'8
4.4 Inspection Procedure ..::.::.....:. ..: .....
4.5 :-Stormwater O.utfalls.......................................................... •• .. ............... .9
Section 5 - References ......•• .. .... 10 ... . .
Appendices
A — Buck Combined Cycle Station Ash Basin — Inspection for Identification of New Discharges
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1 Duke Energy,carolinas, LLC_ I Plan for- Identification of New Discharges
Buck Combined. Cycle Station Ash Basin
SECTION 1- INTRODUCTION
l-_
Soction 1 Introduction
The purpose of this document�is'to address.the requirements of North Carolina.General Statute
(.GS).130A-309.210 (d); Identification and assessment of discharges, correction of unpermitted
discharges, as:modifibd by: North Carolina Senate Bill::729, for the Buck. Combined Cycle Station
(BCCS): ash basin operated under National Poll utant.Discharge Elimination System (NPDE�S)
Permit NC0004774. '.
The following: requirements.are Contained in General Statute 130A-309.210:
d) Identification of New Discharges. — No later than October 1, 2014; the
owner of a coal combustion. residuals surface: impoundment shall: submit a
proposed Plan for the: Identification of New Discharges to the. Department for its::
review and approval as provided:in.this subsection..:.
1) The proposed :Plan for the Identification of New Discharges shall include,
at a minimum, all of the following:
a.: 'A procedure for ro' a inspection of: the: coal combustion.residuals
. .......... .
surface impoundment to identify indicators of potential new
_ discharges, including toe drain' outfalls, seeps, and weeps.
b.. A procedure for determining whether a new discharge is actually
present. .
c.:.A procedure for'notifying.the Department. when anew discharge. is
confirmed.
d. Any other information related to the identification of:new discharges
required by the.Department.
2) The Department shall approve the Plan for; the Identification of New'
Discharges if it determines that the Plan complies:with the requirements
of this subsection and will be sufficient. to protect publichea/th, safety,
t and welfare; the environment and natural resources.
3). No later than.30. days from the approval of the Plan. for -the Identification ..
of New Discharges,; the owner shall begin implementa(ion: of the Plan in .
accordance with the Plan:.
The North Carolina Senate.Bill 729 establishes the -submittal date.'of.this Plan for Identification
...of New Discharges no. later than October.1, 2014.
This bill also modified GS 130A to establish the following submittals that are related ao this Plan.
GS130A-309.21.0(a) was modified Ito require:
2)..No later -than December 31, 2014, the'owner of a'coa/ combustion
. residuals surfacew.,impoundment shall: submit a topographic map that:
identifies the location: of all (i) outfalls from engineered channels
designedor.. improved for the purpose. of collecting water. from: the toe of. .
the impoundment and (ii) seeps and weeps discharging from the
impoundment that are not captured by engineered channels designed or

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Duke Energy Carolinas, LLC. Plan forldentifrcation of New Discharges
Buck:Combined.Cycle Station Ash Basin ..
SECTION 2-'SITE DESCRIPTION. :.
Section 2:-::Site Description
2.1 Plant Description
- Duke Energy formerly operated Buck Steam Station (BSS); a coal-fired. electricity generating
q.facility with a capacity of 256 megawatts located; in .Rowan Count y,.'North.Carolina, near the:.
town -of Salisbury:: The.BCCS has been co -located with the.former BSS facility,:and, as of April
q.
2013, all of the coal=fired units at BSS have been retired. The Buck site,is located northwest of
Leonard Road- and is situated between several residential properties and the, dkin River:
Road y y
Leonard Road enerall runs from southwest to northeast in :the vicinity of: tfiete and is
located along a.topographic.divide.. The topography at the site generally.slopes downward from
that divide: toward the Yadkin: River. The entire Buck'site is approximately 640 acres in. area.
2.2: Ash Basin: Description;
... ...
The ash: basin. system at the Buck site was used toretain and settle ash generated from coal
combustion at the -retired coal-fired units. -The ash basin -system consists of threecells, the
associated earthen dikes, discharge structures, and two canals. The cells are designated as
..
Cell 1 Additional Primary Pond.(Pell 1), Cell 2 Primary Pond (Cell 2), and Cell 3 Secondary:
Pond (Cell 3). The ash basin is located to the south (Cell 1). and southeast. (Cells.2 and 3) of:. -
the retired BSS Units j through 6 and the BCCS Plant. The original ash pond:at the Buck site
began operation in 1957 and was formed by constructing a dam across a tributary of the'Yadkin
River. ..The:footprint of the original ash pond. was the approximate current footprint of Cells 2_ ,-
1 and: 3.: As the ash pond capacity diminished over time, the -original pond was.everitually divided: -
into two: ash ponds (Cells 2 and-3) by construction of_a separate dike: :In.1982; additional:
- storage:was created by construction of Cell 1,: separate from the other cells, by building: a new
dike upgradient from Cell. 2.
ws
Until Cell 1 was constructed, ash generated from the coal combustion' was sluiced (vial
ash discharge lines) to Cell 2: Following construction of Cell 1, sluicedash:was re-routed from
Cell 2:to Cell 1. Flow from Cell 1 enters -Cell 2 via the Primary.Cell Discharge Tower. Flow from :;
Cell 2 enters :Cell 3 via the Old Primary Cell Discharge Structure.: Flow%from Cell 3 discharges
to the -Yadkin River through the Secondary Cell Discharge Tower.
The'approximate, pond elevations, for the three ash basin cells are: Cell 1 —pond elevation 705
r' feet; Cell 2--pond elevation 682.feet; Cell 3—pond elevation 674 feet::The elevation of the
Yadkin River near the. site is approximately. 624 feet.
The area contained within the waste boundary:for Cell 1 encompasses—approximately.90 :a.cres.
For.purposes of delineating the waste boundary; Cells 2 and.3-are considered a single unit; with
the area contained within: this portion of the waste boundary. encompassing approximately 80.7
acres. Cell. 3: was developed by: increasing the elevation of the earthen dike along the Yadkin
River.and constructing an intermediate dike. across the ash placed in -:Cell 2.
The ash basin system is operated.as an integral part.of the site's wastewater treatment system.
During operation of the coal-fired units, the ash basin received variable inflows from the ash
removal system and other permitted.discharges. Currently, the ash basin receives: variable
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Duke Energy Carolinas, LLC:I Plan_for Identification of New.Discharges
Buck Combined -Cycle Station Asti Basin
SECTION 2:7'SITE DESCRIPTION
Table:1. Current: Permitted NPDES Wastewater and Stormwater Outfalls
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' NPDES Outfall
Wastewater '"
Outfalls
:Description of Waste Stream
Description of:EfFluent -
001
Once -through; non -contact'
Cooling water for now retired.Buck Steam Station units.
cooling:water
Coal pile runoff, ash transport water, metal:cleaning wastes,
= 002
Treated water from the ash basin_
treated domestic wastewater, rerrediated groundwater, low .
volume wastes, blowdown from wet, cooling -towers for
combined cycle unit, and boiler blowdown.
002A :.::
Yard sum .overflows
Stormwater
Outfall Description and
Drainage Area Runoff Description
Outfalls
. Receivin Water Body
12-inch=diameter corrugated-
Drainage area:runoff from paved parking lot, part of the. Unit
SWO01
metal pipe (CMP) to Yadkin
5 and 6 Switchyard,. and grassed area adjacent to Unit 5 and
River:..
6:switch ard.
Drainage area, runoff from gravel -surface Unit 5 and 6.
Switchyard, a small paved area beneath Unit 8 and 9
SWO02
21=in6fi=diameter CMP to Yadkin
Precipitators located north of the Switchyard; and.
River
approximately 0.3 acre of paved parking located west of the
switch ard.
Drainage area runoff encompasses the Service Building
SW003
10-inch=diameter CMP to Yadkin
roof, a small storage shed roof, a covered' compressed gas'
River .
storage:pad, a vapor extraction tank, paved driveways, and
landscaped areas on:the west side of the Service�Buildin .
Drainage area runoff from the western.half:of the Unit 3 and
4 Switchyatd� The drainage area -is gravel surfaced.
SW048
15-inch-diameter steel pipe to
Electrical equipment including transformers and circuit
the Yadkin River
breakers are located'within curbed concrete'contaihment
m al
ads with manual) operated dra' .v ves.
Drainage area runoff from large,. prim;arilyvegetated area
36-incFi-diameter CMP to the
located east of Drainage Area 56. The drainage area
SW073
Yadkin: River
contains approximately.1,000. linear feet of rail lines and
approximately 2,000 linearfeetof ravel -surfaced roadwa .
Drainage area:runoff from a gravel roadway and gravel-
surfaced:areas surrounding rail lines: near the yard sump.
SW075
30-inch-diameter CMP to the
drainage area contains approximately 500 linearfeet of
Yadkin River
:The
rail lines and approximately 250 linear feet of:gravel
roadway.
Drainage -area runoff from graveksurfaced areas
surrounding rail lines near the yard sump. The drainage. area
SW077
36-inch-diameter•CMP to the
also includes portions of a,grassed embankment north :of the
Yadkin: River _
cbm6Uttion turbine units'. Approkimately 1,200 linear feet of
rail lines are -located within the drains a area.
Powerhouse
Roof Drain.
Outfalls (Outfalls
SW005; SW007,
$V1I011, SW015,
Drainage areas for these outfalis are comprised entirelyof
SW016, S1IV023, .:
various sections of the Powerhouse roof. These outfalls are
SW025, SW0271
21,small steel pipes
- mounted on the north face of. the Powerhouse wall; ..
SW032; SW0341
discharge directly into the station.intake:area, and are
SW035, SW038,
inaccessible.''
SV1I039; $W058,
SW065, SW066,
SW„06.7, SVV06bi
SW070; SW071,
and SW072

Duke Energy_ Carolinas, LLC I Plan:forldentification ofNew:Discharges
• Buck Combined. Cycle Station Asti Basin '
SECTION 3 - SITE GEOLOGY AND HYDROGEOLOGY .
Section.3 -Site Geology and Hydrogeology
3..1 Site Geologic/Soil Framework
Th:e Buck site ash basin system;is located'in the Charlotte terrane of the Piedmont'
physiographic province (Piedmont). The following generalizations on; the site hydrogeologyare
taken from A Master.Conceptual Model fdr,Hydrogeological.Site Characteeizatio:ri in the
Piedmont and Mountain Regions of North: Carolina, (LeGrand 2004).
Piedmont bedrock -primarily consists: of igneous and metamorphic bedrock. The fractured
bedrock is overlain by a mantle of unconsolidated material known as regolith,-The regolith'
includes, where present, the soil zone, a zone.of weathered, decomposed bedrock known 'as
saprolite, and where present, -alluvium. Saprolite;'the'product of chemical and mechanical
weathering of the. underlying bedrock, is.typically composed of clay and coarser granular
material up to boulder size:and''may reflect the texture:of the rock:from which it was formed.:.
The weathering: product of granitic rocks. may be quartz -rich and sandy -textured, whereas:rocks
popr.in quartz and rich in:feldspar and other:soluble minerals form a more clayey.saprolite. The.
re olith :Serves:as the ' rincl al stora a reservoir for the undetl In bedrock LeGrand 2004
3.2 Site Hydrogeologic -Framework
Piedmont topography is characterized by gently rounded sloped hills and valleys. Recharge
typically. occurs:on upland areas. and slopes while.groundwater discharge is concentrated.in
surface water bodies. and lowland areas.:LeGrand's (19.88, 2004) conceptual model of the
... groundwater setting in the Piedmont: incorporates the .above two medium systems,into an entity
i
that is useful :for the description of groundwater conditions. That entity is the surface drainage
basin: that contains a perennial stream or, river (LeGrand 1988).: Each basin is similar to
adjacent basins and'the.conditions. are: generally repetitive from.basin to basin: Within a basin,
-; movement of groundwater is generally restricted to the area extending from the drainage divides
;! to a. pqrOnni8lstream,or river Slo a -A uifer S stem; LeGrand:1988, 2004). Rarel does
groundwater move beneath a perennial stream or river to another more distant stream (LeGrand
2004). :
Therefore, in most cases: in the Piedmont, the groundwater system is a two. -medium system
(LeGrand 1988) restricted to the: local drainage basin.. The groundwater occurs in a. system.
composted ofawo interconnected, layers: residuum/saprolite and weathered rock overlying :
fractured crystalline rock separated by the transition zone. Typically, the residuum/saprolite is
q.
I- .I partly saturated. and the'water table fluctuates, within it. Water movement is generally through
the fractured bedrock. The-near.=surface fractured crystalline rocks:can form extensive aquifers.
The character of such aquifers results from :the combined effects of the rock type, fracture
system, topography, and'weathering..Topography exerts:aninfluence on bothweathering and
the opening of fractures while the weathering of the crystalline rockmodifies both transmissive
and: storage' characteristics.
- The aquifer system in the Piedmont typically exists :in .an unconfined or semi -confined condition
in the bedrock zone. Under natural conditions, the general direction of groundwater flow can be
approximated from the: surface topography. :Groundwater. moves both vertically. down through .
6

Duke Energy Carolinas, LLC I Plan forldentification of New:Discharges
Buck Comhined.Cycie Station Ash Basin FN
SECTION 4 - IDENTIFICATION.OF NEW DISCHARGES
Section, 4 : Identification of. New Discharges
4.1 Purpose of inspection
The -purpose of.the inspection is: to. identify new discharges and indicators of potential new.
discharges, ;including toe d.rainoutfalls, seeps, andweeps associated with the coal combustion
residuals surface impoundment (ash :basin).
4.2 Seepage
Seepage is considered to be the movement of wastewater from the ash basin.thro.ilgh the ash
basin embankment, the embankment foundation, the. embankment abutments,: through residual
material 1n.areas adjacent to the: ash basin, or through the bottom of the ash basin (if the flow
'eventually reaches the: ground surface). Therefore, a seep is defined in this document as an
expression of seepage at the ground surface above the ordinary high water mark of any waters . .
of the sfate: A weep is understood to have the same meaning as.a seep.
i
Indicators of seepage include areas Where water is observed on the ground surface and/or
Where Vegetation suggests: the presence of'Seepage.- ,Seepage can emerge anywhere On the
downstream face, beyond the -toe, or on the downstream abutments at:elevations below:n'ormal
pool.. Seepage may.vary in appearance from a "soft," wet area to a flowing "spring:." Seepage:
may show up first as'only an area where:theevegetation is lusher:and.darker green than .
surrounding: vegetation. CattaiIs,:reeds, mosses;.and:other marsh vegetation often become
r -
established in a seepage: area.' However, in many instances; .indicators of seeps: do not
necessarily indicate the presence .of seeps.
4.3 .::Area To Be :Inspected for; New'Discharges
The.areas to beinspectedfor new discharges -and indi,cators:of potential.new discharges, are the
areas of:the:site where water: contained in the'ash: basin might infiltrate into the underlying
residual material and be:expressed as seepage. This would:include the earthen embankment
q.
which impounds the ash basin and certaih-adjacent areas:.::
The extent'of.the areas to be:inspected was determined based on the generalized LeGrand
conceptual model the, concept of the slope -aquifer system,. -and: the site topography. In this
generalization, flow of water from the ash basin would-be'expected to -be located within the
slope -aquifer compartment arld to be below the full:pond elevation of.the: ash basin. The areas
to be inspected are shown on Figure 2.
4.4 Inspection Procedure
-The inspection procedure for identification of new discharges and indicators of potential new
! discharges associated with the Buck ash basin system is provided in Appendix A. -In addition to
the specific requirements for the: inspection, Appendix A also providesahe general requirements,
the frequency of inspections, documentation requirements, and :provides a; decision flow chart
for: determining if :the:potential new discharge is associated: with.the ash basin::
' Dam :Operation, Maintenance, and Inspection Manual, North Carolina Department of Environment and
Natural Resources, -Division of Land Resources,:Land Quality Division, 1985 (Revised;200,7).
8

Duke Energy Carolinas, LLC I Plan for Identification of New Discharges ���
Buck Combined Cycle Station Ash Basin
SECTION 5 - REFERENCES
MI

SITE LOCATION MAP
BUCK COMBINED CYCLE STATION
DUKE ENERGY CAROLINAS, LLC
ROWAN COUNTY, NORTH CAROLINA
SEPTEMBER 30, 2014
FIGURE
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