NC0004979_Groundwater Information_20141015

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Groundwater Information
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RECEI
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2014
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OCT 5
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Allen Ash Basin (NPDES Permit NC0004979)RECEIVEDIDENRIDWR
Groundwater Monitoring Program
Reports and Recommendations OCT 1 5 2014
Water Quality
Permitting n
Groundwater monitoring is conducted around the ash basin system at the Allen Steam Station
under NPDES Permit NC0004979. The following items are presented to describe potential on-
site and off-site receptors, the nature of the groundwater flow regime around the Allen site, and
the Allen groundwater monitoring program.
• Item 1 - Receptor Survey Allen Steam Station Ash Basin
• Item 2 - Generalized Groundwater Flow Direction Figure
• Item 3 - Groundwater Monitoring Program Sampling, Analysis, and Reporting Plan
The referenced items and documents are included to describe the current state of the groundwater
monitoring program and any changes to the existing monitoring plan. Changes to the current
program (including installation of additional observation or monitoring wells) which are
proposed by Duke Energy in the future may be allowed following consultation with NCDENR
and should not require a re-opening of the Allen NPDES permit.
Item 1 - Receptor Survey Allen Steam Station Ash Basin
A receptor survey has been completed to identify private water supply wells, public water
supplies, surface water bodies, and wellhead protection areas(if present) within a 0.5-mile radius
of the Allen ash basin compliance boundary. The report presents the methodology and findings
of the survey. This report is included as Enclosure 1.
Item 2 - Generalized Groundwater Flow Direction Figure
The Allen ash basin site and the generalized groundwater flow directions for the shallow water
table are presented in a figure contained in Enclosure 2. The figure presents the generalized
groundwater flow direction around the ash basin with arrows depicting probable generalized
groundwater flow directions for the shallow water table. These generalized flow directions were
developed based on the site hydrogeologic conceptual groundwater flow model, site topography,
and historic site groundwater elevation data.
Item 3 - Groundwater Monitoring Program Sampling,Analysis, and Reporting Plan
The groundwater monitoring program sampling, analysis, and reporting plan (Plan) was
developed to support the requirement for groundwater monitoring around the Allen ash basin.

The Plan describes the groundwater monitoring network, methodologies of field sampling,
record-keeping protocols, analytical procedures, data quality objectives, data validation, and
reporting that will be used to support the Allen ash basin groundwater monitoring program. This
document is included as Enclosure 3.
As stated in the Plan, it is recommended that sample reporting requirements be changed to
require reporting within 60 days of the date of sample collection. It is recommended that the
compliance monitoring wells at the Allen site continue to be sampled at a frequency of three
times per year and analyzed for the same constituents that have been historically analyzed for the
NPDES-required groundwater monitoring.
We also plan to develop a groundwater flow model of the site predicting expected groundwater
flow paths from areas around the ash pond system to the appropriate receiving water body. The
groundwater flow model would be used to verify the current understanding of the groundwater
flow directions at the site and could be used to evaluate exceedances if any are found to be
related to impacts from the ash basin. We propose that model will be developed and the
groundwater flow modeling report be submitted to NCDENR within 120 days of the NPDES
permit being issued. As plans are made to develop the groundwater flow model, the installation
of additional observation wells in or around the ash basin system may be beneficial to enhance
the model. If Duke's evaluation deems additional observation wells to be beneficial, we will
communicate our recommendations to NCDENR prior to well installation.
NCDENR Aquifer Protection Section (APS) developed a policy for compliance evaluation of
groundwater results at ash basins with no prior groundwater monitoring and published a
memorandum providing that policy on June 17, 2011. The memorandum titled Policy for
Compliance Evaluation of Long-Term Permitted Facilities with No Prior Groundwater
Monitoring Requirements outlined the process for evaluating compliance of groundwater
monitoring results based on the requirements in 15A NCAC 2L .0106.
The memorandum acknowledges the factors that monitoring well placement and existing
conditions at the ash basins have on determination of exceedances of 2L Standards in
groundwater monitoring results at ash basins.
The memorandum included a flow chart showing the process for determining if a measured
groundwater concentration greater than 15A NCAC 02L .0202 would cause the facility to be
non-compliant and would result in implementation of corrective action.
Duke recommends continued utilization of the June 17, 2011, NCDENR memorandum to
evaluate exceedances of 2L Standards at the Allen ash basin. For exceedances that are not the
result of naturally occurring site conditions, the process prescribed in the nReireeptereforDwR
OCT 152014
Water Quality
Permitting Section

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the permittee to comply with corrective action requirements as specified in 15A NCAC 02L
.0106.
Enclosures: Enclosure 1 —Receptor Survey Allen Steam Station Ash Basin
Enclosure 2—Generalized Groundwater Flow Direction Figure
Enclosure 3—Groundwater Monitoring Program Sampling,Analysis, and
Reporting Plan

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RECEPTOR SURVEY
ALLEN STEAM STATION ASH BASIN
NPDES PERMIT NC0004979
tw‘i
DU
ENERGY®
Prepared for:
DUKE ENERGY CAROLINAS, LLC
Charlotte, North Carolina
Prepared by:
HDR ENGINEERING, INC. OF THE CAROLINAS
Charlotte, North Carolina
October 10, 2014
RECEIVED/DENR/DWR
OCT 1 5 2014
vvater.tuai$ty
Permitting Section

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REPORT VERIFICATION
PROJECT: RECEPTOR SURVEY
ALLEN STEAM STATION ASH BASIN
NPDES PERMIT NC0004979
This document has been reviewed for accuracy and quality commensurate with the intended
application.
Prepared by: ekzf Date: /a))01
Checked by: Sito Date: jp//6420i Y
Approved by: Date: l b/ 10 in 14
Project Manager: Brooke Ahrens, PE
RECEIVED/DENR/DWR
OCT 152014
Pewaternrtltting QS�

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RECEPTOR SURVEY
ALLEN STEAM STATION ASH BASIN
NPDES PERMIT NC0004979
TABLE OF CONTENTS
Section Page No.
SECTION 1 INTRODUCTION 1
SECTION 2 BACKGROUND 2
2.1 Plant and Ash Basin Description 2
2.2 Description of Surrounding Properties 3
SECTION 3 RECEPTOR SURVEY ACTIVITIES 4
3.1 NCDENR Records Review 4
3.2 Gaston County Records Review 4
3.3 Mecklenburg County Records Review 5
3.4 Utility Department Records Review 5
3.5 HDR Field Survey 6
3.6 USGS Hydrography Review 6
SECTION 4 FINDINGS 7
4.1 NCDENR Records 7
4.2 Gaston County Records 7
4.3 Mecklenburg County Records 8
4.4 Utility Department Records 8
4.5 HDR Field Survey Findings 8
4.6 Summary of Receptor Survey Findings 10
FIGURES
Figure 1 Receptor Survey Map
TABLES
Table 1 Public and Private Water Supply Wells
(Within 0.5 Mile Radius of Ash Basin Compliance Boundary)
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Section 1
Introduction
Duke Energy Carolinas, LLC (Duke Energy) owns and operates the Allen Steam Station(Allen),
located in Gaston County, North Carolina near the town of Belmont (Figure 1). Allen has been
operating as a coal-fired generating station since 1957.
Coal ash residue from Allen's coal combustion process has historically been disposed of in the
station's ash basin. The discharge from the ash basin is permitted by the North Carolina
Department of Environment and Natural Resources (NCDENR) Division of Water Quality
(DWQ) under the National Pollutant Discharge Elimination System (NPDES) Permit
NC0004979.
HDR Engineering, Inc. of the Carolinas (HDR)has completed a receptor survey to identify water
supply wells, public water supplies, surface water bodies, and wellhead protection areas (if
present) within a 0.5 mile radius of the Allen ash basin compliance boundary (Figure 1).' The
compliance boundary for groundwater quality in relation to the ash basin is defined in
accordance with 15A NCAC 02L .0107(a) as being established at either 500 feet from the waste
boundary or at the property boundary,whichever is closer to the source.
The survey activities performed and the findings of those activities are presented in Sections 3
and 4,respectively.
1 A Drinking Water Supply Well and Receptor Survey, Allen Steam Station Ash Basin, NPDES Permit NC0004979
report dated September 30, 2014 (submitted to NCDENR under separate cover), was completed to satisfy the
requirements outlined in The Coal Ash Management Act 2014-General Assembly of North Carolina Senate
Bill 729 Ratified Bill(Session 2013)and the NCDENR August 13,2014 Notice of Regulatory Requirements.
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Section 2
Background
2.1 Plant and Ash Basin Description
Allen is a five-unit coal-fired electric generating plant with a capacity of 1,140 megawatts
located on the west bank of the Catawba River on Lake Wylie, in Belmont, Gaston County,
North Carolina. The site is located east of South Point Road (NC 273) and is generally situated
between residential properties and Lake Wylie (Figure 1). The station's ash basin is situated
between the Allen station to the north and surface water divides to the west (along South Point
Road) and south (along Reese Wilson Road), which both drop in elevation to the east toward
Lake Wylie. The surface water divide along South Point Road likely functions as a groundwater
divide. The topography at the site generally slopes downward from that divide toward Lake
Wylie. The entire Allen site is approximately 1,009 acres in area.
The station's ash basin consists of an active ash basin and an inactive ash basin. The active ash
basin was commissioned in 1973 and is currently in operation.' The inactive ash basin is located
to the north of the active ash basin and is not in operation. A large portion of the area on top of
the inactive ash basin is permitted as an industrial landfill by the NCDENR Division of Waste
Management (Permit No. 3612). The ash basin waste boundary, which is shown on Figure 1, is
approximately 322 acres in area.
There are two earthen dikes impounding the active ash basin; the East Dike, located along the
west bank of Lake Wylie and the North Dike, separating the active and inactive ash basins. The
surface area of the active ash basin is approximately 169 acres' with an approximate operating
pond elevation of 633.5 feet'. The full pond elevation of Lake Wylie is approximately 568.7
feet. The ash basin is an integral part of the station's wastewater treatment system, which
receives flows from the ash removal system, coal pile runoff, landfill leachate, flue-gas
desulfurization(FGD)wastewater,the station yard drain sump, and stormwater flows.
2 Information obtained from Duke Energy Carolinas, LLC CERCLA 104(e) Request for Information to US
Environmental Protection Agency,Allen Steam Station,dated March 26,2009
'The datum for all elevation information presented in this report is North American Vertical Datum of 1988.
2

Section 2 Background
Due to station operations and weather, the inflows to the ash basin are highly variable. The
inflows from the ash removal system and other plant discharges are discharged through sluice
lines into the ash basin. Prior to 2009, all of the fly ash produced was sluiced to the ash basin.
Since 2009 fly ash has been dry-handled and is infrequently sluiced to the ash basin. All of the
bottom ash produced by the station is sluiced to the ash basin.
Effluent from the ash basin is discharged from the discharge tower via a 42-inch diameter
reinforced concrete pipe, to Lake Wylie. The water surface elevation in the ash basin is
controlled by the use of stop logs in the discharge tower.
2.2 Description of Surrounding Properties
Properties located within a 0.5 mile radius of the Allen ash basin compliance boundary generally
consist of Allen to the north with residential properties beyond, residential properties in Gaston
County to the west and south, and residential properties in Mecklenburg County to the east and
southeast across Lake Wylie.
Figure 1 depicts the general land use surrounding Allen.
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Section 3
Receptor Survey Activities
3.1 NCDENR Records Review
On July 10, 2014, Mr. Justin Schumacher with HDR contacted Mr. Sean McGuire, Geographic
Information System (GIS) Specialist with the NCDENR Department of Environmental Health
(DEH) Public Water Supply Section (PWSS), by telephone. Mr. McGuire stated that the Public
Water Supply Water Sources GIS point data set was in the process of being updated. The most
current GIS data set of public water supply locations available from North Carolina state
agencies was provided by Mr. McGuire via electronic mail on July 14, 2014. The GIS point data
for the public water supply wells includes, but is not limited to information such as public water
supply (PWS) system identification numbers, ownership information, PWS source type, well
depth, and well yield. HDR reviewed the GIS data set to identify public water supply sources
within a 0.5 mile radius of the Allen ash basin compliance boundary.
On August 14, 2014, HDR reviewed the NCDENR Division of Water Resources (DWR) Source
Water Assessment Program (SWAP) online database for public water supply sources to identify
wells located within a 0.5 mile radius of the ash basin compliance boundary, to confirm the
location of wells included in the Public Water Supply Water Sources GIS point data set, and to
identify wellhead protection areas located within a 0.5 mile radius of the compliance boundary.
The NCDENR SWAP database provides detailed assessments of all public drinking water
intakes and wellhead protection areas in North Carolina. The website address is:
(http://swap.ncwater.org/website/swap/viewer.htm).
3.2 Gaston County Records Review
HDR contacted the Gaston County Environmental Health Department to inquire about the
location and details (if available) for registered private water supply wells located in Gaston
County within a 0.5 mile radius of the ash basin compliance boundary. On August 15, 2014, Mr.
Justin Schumacher with HDR contacted Ms. Samantha Dye, Assistant Administrator with the
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Section 3 Receptor Survey Activities
Gaston County Environmental Health Department. Ms. Dye informed Mr. Schumacher that she
researched Gaston County's records, which date back to 1989, for private and/or public water
supply wells within a 0.5 mile radius of the ash basin compliance boundary.
3.3 Mecklenburg County Records Review
On August 14, 2014, HDR reviewed Mecklenburg County's Groundwater and Wastewater
Services Well Information System online database to identify private or public water supply
wells located in Mecklenburg County within a 0.5 mile radius of the ash basin compliance
boundary. Established in 2002, the database provides Mecklenburg County's collection of data
about well and septic system permitting, subsurface investigation permitting, monitoring well
registration and abandonment, and Mecklenburg Priority List sites. The website address is:
(http://meckmap.mecklenburgcountync.gov/WIS 3/index.html).
3.4 Utility Department Records Review
HDR contacted Charlotte-Mecklenburg Utilities Department (CMUD) to inquire about
municipal water supply to properties located in Mecklenburg County within a 0.5 mile radius of
the ash basin compliance boundary. On August 15, 2014, Mr. Justin Schumacher with HDR
spoke with Ms. Page with CMUD new services. Mr. Schumacher provided tax parcel
information obtained from Mecklenburg County's online Property Ownership and Land Records
Information System(POLARIS) to inquire about municipal water supply to properties located in
Mecklenburg County within a 0.5 mile radius of the ash basin compliance boundary.
HDR contacted the Belmont Water and Sewer Department to inquire about municipal water
supply to properties located in Belmont and Gaston County within a 0.5 mile radius of the ash
basin compliance boundary. On August 19, 2014, Ms. Brooke Ahrens with HDR spoke with Mr.
David Isenhour, Director of Public Works for the Belmont Water and Sewer Department. Mr.
Isenhour stated that the referenced PWS wells (Figure 1) are the County's jurisdiction and not
the City of Belmont.
5

Section 3 Receptor Survey Activities
3.5 HDR Field Survey
HDR personnel performed a field reconnaissance on March 19, 2014 to attempt to identify water
supply wells located within a 0.5 mile radius of the ash basin compliance boundary. A
windshield survey was conducted from public roadways to identify water meters, valves, and any
potential well heads/well houses. Prior to conducting the field reconnaissance, HDR personnel
reviewed orthophotography obtained from NC OneMap GeoSpatial portal (dated 2010) to
identify potential well heads/well houses and surface waters within a 0.5 mile radius of the ash
basin compliance boundary.
3.6 USGS Hydrography Review
HDR reviewed the United States Geological Survey (USGS) National Hydrography Dataset
(NHD) obtained from the USGS National Map Viewer (http://viewer.nationalmap.gov/viewers
to identify any surface waters within a 0.5 mile radius of the ash basin compliance boundary.
Hydrography data obtained from the USGS NHD is included on Figure 1.
6

Section 4
Findings
Details of the findings from the local and state records review and field survey activities are
provided in Sections 4.1 through 4.5. A general summary of the receptor survey findings is
provided in Section 4.6.
4.1 NCDENR Records
Four public water supply wells were identified in the PWSS's GIS point data set(obtained from
NC OneMap GeoSpatial Portal) located within a 0.5 mile radius of the ash basin compliance
boundary. These four identified public water supply wells were included on the NCDENR
SWAP online database (Figure 1). These wells are identified with PWS preceding the Public
Water Supply System ID Number as it is referenced to available well information provided in
Table 1.
No wellhead protection areas were identified on the NCDENR SWAP online database within a
0.5 mile radius of the ash basin compliance boundary.
4.2 Gaston County Records
On March 28, 2014, Ms. Lisa Wright, Environmental Health Specialist Tech with the Gaston
County Environmental Health Department,provided Gaston County's available well information
for 36 registered private water supply wells located within a 0.5 mile radius of the ash basin
compliance boundary. These wells are identified with PRW preceding the identification number
as it is referenced to available well information provided in Table 1. The locations of the wells
are identified on Figure 1 as "recorded" private water supply wells. On August 15, 2014, Ms.
Dye confirmed that no new wells have been registered since March.
The Gaston County Environmental Health Department indicated they have no records for public
water supply wells within a 0.5 mile radius of the ash basin compliance boundary.
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Section 4 Findings
4.3 Mecklenburg County Records
Mecklenburg County's Groundwater and Wastewater Services Well Information System online
database, which was established in 2002, included 13 registered private water supply wells
located within a 0.5 mile radius of the ash basin compliance boundary. One of the 13 private
water supply wells has a status of permanently abandoned. Available well information for the
identified wells is provided in Table 1. These wells are labeled with PRW preceding the number
as it is referenced to available well information provided in Table 1. The locations of the wells
are identified on Figure 1 as"recorded"private water supply wells.
4.4 Utility Department Records
The Belmont Water and Sewer Department maintains a 12-inch water service main located along
South Point Road (Highway NC 273) south to Armstrong Road and along Armstrong Road to
the Lake Point subdivision. Mr. Isenhour indicated that the City of Belmont supplies water to
the Fire Station located at 2300 South Point Road, Duke Energy Allen Steam Station, and two
subdivisions located to the south (Reflection Pointe) and the southwest (Lakepoint) beyond the
0.5 mile radius of the ash basin compliance boundary. Furthermore, Mr. Isenhour noted that
there are several public water supply wells managed by Aqua North Carolinas, Inc. in the area
that provide water service to residential developments. Available property and well information
pertaining to four public water supply wells identified in the PWSS's GIS point data set and the
NCDENR SWAP online database (described in Section 4.1), and owned by Aqua North
Carolinas,Inc., is provided in Table 1 and locations of the wells are shown on Figure 1.
CMUD does not provide water service to the properties located in Mecklenburg County within a
0.5 mile radius of the ash basin compliance boundary.
4.5 HDR Field Survey Findings
During the field reconnaissance, HDR field personnel identified 164 private water supply wells
at properties located within a 0.5 mile radius of the ash basin compliance boundary.
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Section 4 Findings
Gaston County provided records for 36 of the 164 identified wells. Records for 13 of the 164
identified wells were obtained from the Mecklenburg County online database. The locations of
the 49 wells that Gaston County and Mecklenburg County had records for were confirmed in the
field and are identified on Figure 1 as "recorded" private water supply wells. General well and
property information for these wells is included in Table 1.
The remaining 115 wells identified in the field are included on Figure 1 as "field identified"
private water supply wells.
The locations of the four public water supply wells included in NCDENR's records and located
within a 0.5 mile radius of the compliance boundary were confirmed in the field.
For properties where the structures and potential wells were not visible from a public right-of-
way, HDR was not able to confirm the location or presence of a well. However, based on the
lack of municipal water supply in the area, it is assumed these properties contain private water
supply wells. Approximate locations based on structures identified during the field
reconnaissance and/or orthophotography review are included on Figure 1 as "assumed" private
water supply wells. A total of 22 assumed private water supply wells are located in Gaston
County and 11 assumed private water supply wells are located in Mecklenburg County within a
0.5 mile radius of the ash basin compliance boundary.
From the public roadway, HDR personnel did not identify indications of municipal water supply
for the properties, other than those identified by Mr. Isenhour with the City of Belmont, located
within a 0.5 mile radius of the ash basin compliance boundary.
Several surface water bodies were identified and/or confirmed during HDR's field
reconnaissance. The surface water bodies located within a 0.5 mile radius of the ash basin
compliance boundary generally flow toward the Catawba River from the topographic divide
along South Point Road.
9

Section 4 Findings
4.6 Summary of Receptor Survey Findings
A summary of the receptor survey fmdings is provided below. The identified water supply wells
and surface water bodies are shown on Figure 1. Available property and well information for the
49 water supply wells registered with Gaston County and Mecklenburg County is provided in
Table 1.
• A total of 164 private water supply wells were identified within a 0.5 mile radius of the
ash basin compliance boundary during HDR's field survey. The Gaston County
Environmental Health Department had records for 36 of the 164 identified private water
supply wells, and Mecklenburg County's online database had records for 13 of the 164
identified private water supply wells.
• A total of 33 private water supply wells are assumed at residences located within a 0.5
mile radius of the ash basin compliance boundary. Twenty-two of the 33 assumed wells
are located in Gaston County, and the remaining 11 assumed wells are located in
Mecklenburg County.
• Four public water supply wells were identified within a 0.5 mile radius of the ash basin
compliance boundary.
• Several surface water bodies that flow from the topographic divide along South Point
Road toward Lake Wylie were identified within a 0.5 mile radius of the ash basin.
• No wellhead protection areas were identified within a 0.5 mile radius of the ash basin
compliance boundary.
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FIGURES

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DUKE ENERGY PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY COINCIDENT
WITH DUKE ENERGY PROPERTY BOUNDARY
0.5 MILE OFFSET FROM ASH BASIN
COMPLIANCE BOUNDARY
PUBLIC WATER SUPPLY WELL
FIELD IDENTIFIED PRIVATE WATER SUPPLY WELL
RECORDED PRIVATE WATER SUPPLY WELL
ASSUMED PRIVATE WATER SUPPLY WELL
NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY I DATE
1 ASH BASIN WASTE BOUNDARY IS APPROXIMATE.
3. ORTHOPHOTOGRAPHY WAS OBTAINED FROM NC ONEMAP GIS WI OCT. 10, 2014
4. THE COMPLIANCE BOUNDARY 15 ESTABLISHED ACCORDING TO THE;
S. MECKLENBURG COUNTY BOUNDARY LINE OBTAINED FROM MECKL
6. FIELD IDENTIFIED WELLS WERE OBSERVED DURING HDR'S FIELD RESIN FIGURE
7. RECORDED WELLS ARE BASED ON INFORMATION PROVIDED BY GA
8. ASSUMED PRIVATE WELLS ARE APPROXIMATE AND BASED ON TH 1
9. PUBLIC WELLS ARE BASED ON INFORMATION OBTAINED FROM N )Ll NA
10. HYDROGRAPHY WAS OBTAINED FROM THE USGS NATIONAL MAP

TABLES

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Table 1 •
Public and Private Water Supply Wells
Within 0.5 Mile Radius of Allen Ash Basin Compliance Boundary
Duke Energy Carolinas,LLC/Allen Steam Station
Approximate Well
Well ID Public Water Property Address Parcel ID Reported Distance from Ash Direction WellWellWell Depth
Fiero
System Name (well location) Number Well Use BaBoundary(ft)sin
Basi (R-bp) (R-bp) (g)
Game Como
Comer of Hwy 273 and
PWS:0136255 Heather Community
(Well#1) Glen/Highland Heather Glen Ln 192166 Active1.000 W 505 N/A 40
Belmont,NC 28012
PWS:0136255 Heather Corner of Hwy 273 and Community,
(Well#2) Glen/Highland Heather Glen Ln 199113 780 W 345 N/A 45
Active
Belmont,NC 28012
PWS 2036011 River Lakes S/D Waurview 193488 Community, 1,920 W 900 N/A 34
Belmont,NC 28012 Active •
At the end of Lake Hill Circle Community,
PWS:0136192 South Point Landing Belmont,NC 28012 193360 Active 1,030 W-SW 340 N/A 40
PRW-1 N/A 9200 Egret Ridge 198000 Private, 1,670 SW 505 54 9
Belmont,NC 28012 Unknown
PRW-2 N/A 9201 Egret Ridge 197999 Private, 1,520 SW 225 54 7
Belmont,NC 28012 Unknown
PRW-3 N/A 9205 Egret Ridge 197998 Private, 1,510 SW 525 86 7
Belmont,NC 28012 Unknown
PRW-4 N/A 9209 Egret Ridge 197997 Private, 1,560 SW 805 90 4
Belmont,NC 28012 Unknown _
PRW-5 N/A 9217 Egret Ridge 197995 Private' 1,820 SW 365 94 8
Belmont,NC 28012 Unknown
PRW-6 N/A 9221 Egret Ridge 197994 Private, 2,030 SW 465 100 12
Belmont,NC 28012 Unknown
PRW-7 N/A 9225 Egret Ridge 197993 Private, 2,240 SW 385 125 8
Belmont,NC 28012 Unknown -
PRW-8 N/A 9235 Egret Ridge 197992 Private' 2,520 SW 405 115 10
Belmont,NC 28012 Unknown
PRW-9 N/A 9239 Egret Ridge 197991 Private, 2,640 SW 780 90 12
Belmont,NC 28012 Unknown
PRW-10 N/A 9236 Egret Ridge 197968 Private, 2,600 SW N/A N/A N/A
Belmont,NC 28012 Unknown
PRW-11 N/A 9034 Wing Point 197967 Private, 2,500 SW 300 99 25
Belmont,NC 28012 Unknown
PRW-12 N/A 9224 Egret Ridge 198003 Private, 2,140 SW 505 101 7
Belmont,NC 28012 Unknown
PRW-13 N/A 1 113 Sawtooth Oak Ln 213343 Private, 1,020 S 645 157 80
Belmont,NC 28012 Unknown
PRW-14 N/A 1104 Sawtooth Oak 213340 Private, 540 S 705 146 8
Belmont,NC 28012 Unknown
Page 1 of 3

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Table 1
Public and Private Water Supply Wells
Within 0.5 Mile Radius of Allen Ash Basin Compliance Boundary
Duke Energy Carolinas,LLC/Allen Steam Station
Amate Wen
Wel ID Public Water Property Address Parcel ID Reported DiMir'Sa
shown matrom Ash rya WWellC Well
I) System Name (well location) Number Well Use Basin Compliance from DepthDepthBashi
Yield
Boundary(fl) ( ) (B-bgs) (Wft)
PRW-15 N/A 1108 Sawtooth Oak Ln 213341 Private, 780 S 205 95 23
Belmont,NC 28012 Unknown
PRW-16 N/A 1006 Nutall Oak Ln 213337 Private, 110 S 635 66 100
Belmont,NC 28012 Unknown
PRW-17 N/A 9105 Shorewood 197966 Private' 2,640 SW 325 74 40
Belmont,NC 28012 Unknown
PRW-18 N/A 9022 Wing Point 197943 Private, 2,420 SW 325 38 40
Belmont,NC 28012 Unknown
9PRW-I9 N/A BelmontShorewood
NoC�80 2 Unknown
197944 2,530 SW 680 41 12
PRW-20 N/A 2309 South Point Rd 221888 Private' 550 W 206 100 10
Belmont,NC 28012 Unknown
PRW-21 N/A 2320 South Point Rd 192177 Private, 750 W 186 83 20
Belmont,NC 28012 Unknown
PRW-22 N/A 2330 South Point Rd 192182 Private, 620 W 365 112 10
Belmont,NC 28012 Unknown
PRW-23 N/A 2360 South Point Rd 192126 Private, 760 W N/A N/A N/A
Belmont,NC 28012 Unknown
PRW-24 N/A 2625 South Point Rd 193392 Private' 110 W 180 81 20
Belmont,NC 28012 Unknown
PRW-25 N/A 101 Dana Michelle Ct 193403 Private, 330 S-SW 480 86 20
Belmont,NC 28012 Unknown
PRW-26 N/A 101 Dana Michelle Ct 193403 Private, 450 S-SW 147 128 35
Belmont,NC 28012 Unknown
PRW-27 N/A 129 Midwood Ln 193465 Private' 380 W 126 99 50
Belmont,NC 28012 Unknown
PRW-28 N/A
109 Lake MistPrivate,Private' 2,400 W 305 107 12
Belmont,NC 28012 Unknown
PRW-29 N/A 500 Lake Breeze in 210932 Private, 2,520 W 440 97 18
Belmont,NC 28012 Unknown
PRW-30 N/A 607 Shady Creek Ct 219064 Private' 2,640 W 370 44 50
Belmont,NC 28012 Unknown
PRW-31 N/A 91 Mitchell St 214506 Private, 110 W 305 173 10
Belmont,NC 28012 Unknown
PRW-32 N/A 97 Mitchell St 192187 Private, 520 W 260 105 12
Belmont,NC 28012 Unknown
PRW-33 N/A 101 Mitchell St 192185 Private, 480 W 200 200 15
Belmont,NC 28012 Unknown
PRW-34 N/A 400 Reese Wilson Rd 193536 Private, 1,900 S 165 110 20
Belmont,NC 28012 Unknown
PRW-35 N/A 402 Rax Wilson Rd 193538 Private, 2,200 S 200 95 18
Belmont,NC 28012 Unknown
PRW-36 N/A 2369 South Point Rd 192218 Private' 450 W 146 126 12
Belmont,NC 28012 Unknown
Page 2 of 3

.4
t
Table 1 !
Public and Private Water Supply Wells
Within 0.5 Mile Radius of Allen Ash-Basin Compliance Boundary
Duke Energy Carolinas,LLC/Allen Steam Station
Approximate Well
Well ID Public Water Property Address Parcel ID Reported Distance from Ash Direction p° WeL Casing We0
(shown on from Ash Depth Yield
Figure 1) System Name (well location) Number Well Use Basin Compliance Bub (ft-bp) Depth (gym)
Boundary(ft) (ft-hp)
Ma dfeat[Asus unary'
PRW-37 N/A 8928 Lynn Parker Ln 11332110 Private,Active 1,600 E N/A N/A N/A
Charlotte,NC 28278
PRW-38 N/A 8744 Bracebridge Ct 11332113 Private,Active 2,240 E 528 105 II
Charlotte,NC 28278
PRW-39 N/A 6830 Buckland Rd 11321137 Private,Active 2,630 E 470 87 12
Charlotte,NC 28278
PRW-40 N/A 7020 Buckland Rd 11321134 Private,Active 2,310 E 115 88 10
Charlotte,NC 28278
PRW-41 N/A 7000 ICilpeck St 11330239 Pnvate,Active 1,920 E-SE N/A N/A N/A
Charlotte,NC 28278 _ _
PRW-42 N/A 7016 Kilpeck St 11330238 Private,Active 1,940 E-SE 350 105 20
Charlotte,NC 28278 _
PRW-42A N/A 70161GIpeck St 11330238 Private' 1,940 E-SE 81 0 0
Charlotte,NC 28278 Abandonded
PRW-43 N/A 8345 Lilybet Ln 11330237-Private,Active 1,860 E-SE 340 112 25
Charlotte,NC 28278
PRW-44 N/A 7201 Buckland Rd 11330211 Private, 2,640 E-SE N/A N/A N/A
Charlotte,NC 28278 Unknown _
PRW-45 N/A 7335 Buckland Rd 11330248 Private,Active 2,510 E-SE 205 73 - 10
Charlotte,NC 28278
PRW-46 N/A 8412 Outwell Rd 11330231 Private,Active 1,940 E-SE 390 90 25
Charlotte,NC 28278 -
PRW-46A N/A 8412 Outwell Rd 11330231 Pnvate,Active 1,950 E-SE N/A N/A N/A
Charlotte,NC 28278
PRW-47 N/A 7418 Buckland Rd 11330250 Private,Active 1,970 E-SE 460 84 15
Charlotte,NC 28278
Notes'.
I.Public water supply well information obtained from NCDENR's Public Water Supply Water Sources Geographic Information System(GIS)point data set and
NCDENR's SWAP online database.
2.Information for private water supply wells located in Gaston County was obtained from Ms.Lisa Wright,Environmental Health Specialist Tech,with the Gaston
County Environmental Health Department.
3.Information for private water supply wells located in Mecklenburg County was obtained from Mecklenburg County's Groundwater and Wastewater Services Well
Information System online database.
4.Property address information for private water supply wells obtained from Gaston County and Meckenburg County Interactive GIS websites.
5.Distances between wells and the ash basin compliance boundary are approximate.
6.Community well serves 15+connections or regularly serves 25+year-round residents(ex.cities,towns,subdivisions).
7.N/A indicates not available
8 ft-bgs indicates feet below ground surface
9.gpm indicates gallons per minute
Page 3 of 3

FY
October 10,2014
Mr. Sean DeNeale Via Email: [e-mail]
Duke Energy Carolinas, LLC
Mail Code EC13Z
P.O. Box 1006 RECEIVEDIDENRIDWR
Charlotte, NC 28201-1006
Subject: Generalized Groundwater Flow Directions Figure OCT 1 5 2014
Duke Energy Carolinas, LLC
Allen Steam Station Ash Basin Water Quality
Permitting Section
Dear Mr. DeNeale:
HDR is pleased to provide the attached figure presenting generalized groundwater flow directions
for the shallow water table aquifer adjacent to the ash basin at the Duke Energy Carolinas, LLC
(Duke Energy)Allen Steam Station(Allen).
This letter provides the background on the development of this information.
1.0 Background
Duke Energy owns and operates Allen, a coal-fired electric generating station, located in Gaston
County, North Carolina. Allen uses an ash basin for disposal of ash generated by the coal
combustion process and other water treatment at the coal-fired plant.
In 2011, Duke Energy provided Altamont Environmental, Inc. (Altamont)information on the
groundwater monitoring wells installed at the ash basin and information on the water levels in the
ash basin. Altamont utilized this information along with consideration of adjacent bodies of water
and site topography to develop generalized groundwater direction flow arrows for the areas
adjacent to the ash basins. This information was presented in the report titled Generalized
Groundwater Flow Direction Maps for Ash Basins, Duke Energy Carolinas, LLC, Fossil Stations,
December 12, 2011(2011 Altamont report). The report contained figures with similar generalized
groundwater flow arrows for all seven of the Duke Energy Carolinas fossil station ash basins. The
report was prepared by Altamont staff and was sealed by William M. Miller, PE. The information
from that report is used with the permission of Duke Energy.
As stated in Section 3.0 of the 2011 Altamont report:
The purpose of the Generalized Ash Basin Groundwater Flow Direction Maps,
Figures 1 through 7, is to provide Duke with an interpretation of the generalized
hdrinc.com
440 S.Church Street,Suite 900.Charlotte,NC 28202
T 704-338-6700

l
Mr.Sean DeNeale
October 10,2014
Page 2
groundwater flow directions in the areas surrounding the ash basins. The maps
were developed utilizing existing data that were readily available and with data
collected as part of on-going monitoring at the ash basins. No additional field
investigation was conducted as part of the development of the maps.
The maps are not intended to provide absolute groundwater flow direction data at
a specific location. Rather, they are an interpretation of the generalized
groundwater flow direction for the shallow water table based on readily available
data.
As described in the following sections(Section 4.0, Section 5.0, and Section 6.0),
there may be hydrogeologic conditions present at the ash basins that cause
groundwater flow conditions to differ from the generalized groundwater flow
directions shown on Figures 1 through 7.
The generalized groundwater flow directions were determined based on a consideration of the
information described above, most notably that the sites are located in the Piedmont physiographic
province(Piedmont). In addition,the generalizations of typical Piedmont hydrogeology found in A
Master Conceptual Model for Hydrogeological Site Characterization in the Piedmont and Mountain
Region of North Carolina(LeGrand 2004)apply to these sites.
As stated in Section 5.0 of the 2011 Altamont report,the possible effects of pumping from adjacent
water supply wells were not considered in the development of the generalized groundwater flow
direction arrows.
The groundwater elevations used in development of the generalized groundwater direction flow
arrows were from the compliance groundwater monitoring wells(compliance wells)-wells
monitored in association with the National Pollutant Discharge Elimination System(NPDES)permits
-and from groundwater monitoring wells voluntarily installed by Duke Energy(voluntary wells).
With the exception of shallow voluntary wells AB-5,AB-6A,and AB-6R, no groundwater elevation
data readings were performed on the voluntary wells after March 2011. The compliance wells were
installed in November and December 2010.
Section 7.0 of the 2011 Altamont report discusses the development of the generalized groundwater
flow direction arrows and the relative level of confidence in the interpretation of the generalized flow
direction. The text below was copied from that report:
Groundwater flow direction arrows are used to depict the interpreted direction of
generalized groundwater flow. Three different colors of arrows were used to
indicate the relative level of confidence in the interpretation of the generalized
groundwater flow direction.

Mr.Sean DeNeale
October 10,2014
Page 3
The relative level of confidence in the interpretation of flow direction was
determined by:
• The distance from groundwater monitoring wells or surface water
elevation data
• The number of groundwater data elevation points utilized
• Consideration of the surface topography
Descriptions of the relative confidence levels indicated by groundwater flow
direction arrow colors are as follows:
• Black arrows represent high confidence in the groundwater flow
direction interpretation. The black arrows were used in areas in
which there were several known groundwater or surface water
elevation data points and the surface topography supported the
interpretation of groundwater flow characteristic of typical
Piedmont groundwater flow.
• Gray arrows represent moderate confidence in the groundwater
flow direction interpretation. The gray arrows were used in areas
where at least one groundwater or surface water elevation point
was known or in areas where there was strong surface
topographic data to support the groundwater flow direction
interpretation.
• White arrows represent estimated groundwater flow direction
interpretation. The white arrows were used in areas where there
was little or no groundwater or surface water elevation data and
there was not conclusive surface topographic data to support a
gray arrow.
2.0 Scope of HDR Review and Results
Since limited groundwater elevation data readings were performed on the voluntary wells after the
installation of the compliance wells during November and December 2010 as described in Section
1.0, HDR reviewed the historic groundwater level data available from the compliance groundwater
monitoring wells in conjunction with the current approximate ash basin pond elevation data.
HDR found the generalized groundwater flow direction arrows presented in the 2011 Altamont
report to generally represent the probable direction of groundwater flow for the shallow water table
aquifer. As stated in the 2011 Altamont report,the generalized groundwater flow direction arrows

Mr. Sean DeNeale
October 10.2014
Page 4
present an interpretation of flow direction based on data from the shallow water table aquifer and do
not consider the possible effects of pumping from adjacent water supply wells.
The ash basin pond elevation at Allen is essentially unchanged from the ash basin pond elevation
utilized in the 2011 Altamont report. Based on the topography of the site, the ash basin pond
elevation, and the water levels measured in the compliance wells, it is unlikely that there would be a
significant change in the direction of the groundwater flow as represented by the generalized
groundwater flow direction arrows developed by Altamont.
The generalized groundwater flow directions for the area adjacent to the Allen ash basin are found
on the attached Allen Steam Station Ash Basin Figure Allen-1.
HDR appreciates the opportunity to provide continued support to Duke Energy. Should you have
any questions regarding this submittal or need further information, please do not hesitate to contact
me.
Respectfully submitted,
HDR Engineering, Inc.of the Carolinas
cogr fis fec
SEAL
Scott A. Spinner, P.G. ;� ct
Environmental Geologist
' ` t1�
A. S2243Q�.
cc: Ty Ziegler, HDR "nt�"'s��,
William M. Miller, HDR
Attachments:
Allen Steam Station Ash Basin Figure Allen-1

GENERAL NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. ASH BASIN WASTE BOUNDARY, ASH LANDFILL LIMIT OF WASTE, AND STRUCTURAL FILL BOUNDARY ARE APPROXIMATE.
3. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY.
4. SHALLOW MONITORING WELLS (S) - WELL SCREEN INSTALLED ACROSS THE SURFICIAL WATER TABLE.
5. DEEP MONITORING WELLS (D) - WELL SCREEN INSTALLED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH. SCALE (FEET)
6. TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NC DOT GEOGRAPHIC INFORMATION SYSTEM (GIS) WEB SITE. 500" 0 500, 1000
7. ORTHOPHOTOGRAPHY WAS OBTAINED FROM NC ONEMAP GIS WEB SITE (DATED 2010).
B. THE ASH BASIN COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L .0107 (a). r = 1000'
FEZ
GENERALIZED GROUNDWATER FLOW DIRECTIONS DATE
DUKE ENERGY CAROLINAS, LLC
ALLEN STEAM STATION
NPDES PERMIT #NC0004979
GASTON COUNTY, NORTH CAROLINA
RECEIVED/DENR/DW
FIGURI
OCT 1 5 2014
Water Uuality
Permitting Section
OCT. 10, 2014
ALLEN-1