NC0004961_RBSS-Supplement to WSW and Receptor Survey_20141106

RIVERBEND STEAM STATION ASH BASIN
Supplement to Drinking
Water Supply Well and
Receptor Survey
NPDES Permit NC0004961

November 6, 2014

Duke Energy Carolinas, LLC I Riverbend Steam Station Ash Basin ��
Supplement to Drinking Water Supply Well and Receptor Survey
REPORT VERIFICATION
Report Verification
PROJECT: SUPPLEMENT TO DRINKING WATER SUPPLY WELL AND RECEPTOR
SURVEY
RIVERBEND STEAM STATION ASH BASIN
NPDES PERMIT NC0004961
This document has been reviewed for accuracy and quality commensurate with the intended
application.
Prepared. I.�/
Checked. ,
Approved by:tIA264u I
Project Manager: Brooke Ahrens, PE
Date: 1/420) �/
Date: /G 1 z of `%
Date: l I- 0 n t 4-

Duke Energy Carolinas, LLC | Riverbend Steam Station Ash Basin
Supplement to Drinking Water Supply Well and Receptor Survey
SECTION 1 – INTRODUCTION AND BACKGROUND

1
Section 1 – Introduction and Background
HDR is pleased to provide the attached figure and table presenting identified updates for the
Drinking Water Supply Well and Receptor Survey at the Duke Energy Carolinas, LLC (Duke
Energy) Riverbend Steam Station (RBSS). The updated information was obtained from
responses to water supply well survey questionnaires mailed to property owners within a 0.5-
mile radius of the RBSS ash basin compliance boundary requesting information on the
presence of water supply wells and well usage. This supplement provides the background on
the development of this information.
Duke Energy owns and operated the RBSS, located on the south bend of the Catawba River on
Mountain Island Lake in Gaston County, North Carolina, near the town of Mt. Holly. As of April
1, 2013, the RBSS has been retired from service. RBSS used an ash basin for disposal of ash
generated by the coal combustion process and for water treatment operations at the coal-fired
plant.
On August 13, 2014, Duke Energy received a Notice of Regulatory Requirements (NORR) for
the 14 Coal Ash Facilities owned by Duke Energy in North Carolina, which included
requirements to perform a receptor survey. HDR submitted the Riverbend Steam Station Ash
Basin, Drinking Water Supply Well and Receptor Survey, NPDES Permit NC0004961, dated
September 30, 2014 (Survey) to satisfy the requirements outlined in NC Senate Bill 729 and the
NORR. The scope of this Survey included identification of all receptors within a 0.5-mile radius
(2,640 feet) of the RBSS ash basin compliance boundary. 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 receptors included public and private water
supply wells (including irrigation wells and unused or abandoned wells) and surface water
features within a 0.5-mile radius of the RBSS ash basin compliance boundary. HDR also
identified public water supplies and wellhead protection areas (if present) within a 0.5-mile
radius of the RBSS ash basin compliance boundary. A potential area of interest with respect to
the RBSS ash basin groundwater flow was delineated and presented in the Survey. Based on
the available information, this area is considered to be potentially downgradient from the RBSS
ash basin.
Duke Energy Carolinas, LLC | Riverbend Steam Station Ash Basin
Supplement to Drinking Water Supply Well and Receptor Survey
SECTION 2 – WATER SUPPLY WELL SURVEY QUESTIONNAIRE APPROACH

Section 2 – Water Supply Well Survey
Questionnaire Approach
During the week of October 8, 2014, HDR mailed water supply well survey questionnaires to
property owners within a 0.5-mile radius of the RBSS ash basin compliance boundary
requesting information on the presence of water supply wells and well usage for the properties.
The mailing list was compiled from a query of the parcel addresses included in the Gaston and
Mecklenburg Counties’ GIS databases utilizing the 0.5-mile offset. For each parcel identified, a
letter was mailed to the property owner stating the purpose of the request for information, a
questionnaire, and self-addressed stamped envelope. The letter requested the property owner
provide a timely response to the questionnaire. For property owners associated with multiple
parcels, a questionnaire was mailed for each parcel. A total of 328 surveys were mailed to
property owners.
Questionnaire responses received after October 31, 2014 will be incorporated into the
Groundwater Assessment Report required by Senate Bill 729 (Section 130A-309.209(a)(4)).

Duke Energy Carolinas, LLC | Riverbend Steam Station Ash Basin
Supplement to Drinking Water Supply Well and Receptor Survey
SECTION 3 – WATER SUPPLY WELL SURVEY QUESTIONNAIRE RESULTS

Section 3 – Water Supply Well Survey
Questionnaire Results
Based on the returned water supply well surveys, the following revisions have been made to the
previously submitted information and are reflected in Figure 1 and Table 1 attached to this
supplement:
• The one previously reported “assumed” private water supply well was confirmed to have
a private water supply well located on the property. This well is now identified as a
“reported” private water supply well on Figure 1 and Table 1. The Well ID with a revised
identification is Well 3.

• No new wells were identified by means of the water well survey questionnaires.

Attachments
Figure 1 Drinking Water Supply Well and Receptor
Survey - Updated November 6, 2014
Table 1 Public and Private Water Supply Wells –
Updated November 6, 2014

NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. PARCEL DATA OTHER THAN THE DUKE ENERGY PROPERTY WERE OBTAINED FROM THE GASTON COUNTY GIS WEBSITE.
3. ORTHOPHOTOGRAPHY WAS OBTAINED FROM NC ONEMAP GIS WEB SITE (DATED 2009).
4. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L .0107 (a).
5. MECKLENBURG COUNTY BOUNDARY LINE OBTAINED FROM MECKLENBURG COUNTY GIS OPEN MAPPING DATA PORTAL ON JANUARY 30, 2014
6. THE LOCATION OF THE ASSUMED PRIVATE WATER SUPPLY WELL IS APPROXIMATE AND BASED ON THE LACK OF RECORDS OF WATER SUPPLY
SERVICE AT THE RESIDENCES LOCATED IN MECKLENBURG COUNTY.
7. HYDROGRAPHY WAS OBTAINED FROM THE USGS NATIONAL MAP VIEWER DOWNLOAD PLATFORM ON MARCH 24, 2014
http://nationalmap.gov/viewer.htmi) AND FROM HDR's FIELD RECONNAISSANCE.
8. REPORTED WATER SUPPLY WELL LOCATIONS WERE PROVIDED BY DUKE ENERGY AND ARE APPROXIMATE.
9. ASH STORAGE BOUNDARY AND CINDER STORAGE BOUNDARY ARE APPROXIMATE.
10. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY.
11. SHALLOW MONITORING WELLS (S) - WELL SCREEN INSTALLED ACROSS THE SURFICIAL WATER TABLE.
12. DEEP MONITORING WELLS (D) - WELL SCREEN INSTALLED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.
13. TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NCDOT GEOGRAPHIC INFORMATION SYSTEM (GIS) WEB SITE.
SCALE (FEET)
1500' 0 500' 600'
/" = 600'
DRINKING WATER SUPPLY WELL AND
RECEPTOR SURVEY MAP - UPDATED NOV. 6, 2014
DUKE ENERGY CAROLINAS, LLC
RIVERBEND STEAM STATION ASH BASIN
NPDES PERMIT #NC0004961
GASTON COUNTY, NORTH CAROLINA
DATE
NOVEMBER 6, 2014
FIGURE
11

Table 1
Public and Private Water Supply Wells - Updated November 6, 2014
Within 0.5 Mile Radius of Riverbend Ash Basin Compliance Boundary
Duke Energy Carolinas, LLC/Riverbend Steam Station
Page 1 of 1
Well ID
(shown on Figure 1)
Public Water
System Name Well Owner/ User Property Address
(well location)Parcel ID Number Reported
Well Use
Distance from
Ash Basin
Compliance
Boundary (ft)
Direction from
Ash Basin
Well
Depth
(ft-bgs)
Well
Casing
Depth
(ft-bgs)
Well
Yield
(gpm)
PWS: NC01367706
Duke Power -
Riverbend Steam
Station
Duke Energy Carolinas, LLC
(owner)
175 Steam Plant Road
Mount Holly, NC 28120
175033
(Gaston County)
Unknown
(reported by Duke Energy
as not used for drinking
water once station
connected to Mount Holly
Public Utilities
Department in March
2001)
Approx. 625 Southwest N/A N/A N/A
1 N/A Duke Energy Carolinas, LLC
(owner)
175 Steam Plant Road
Mount Holly, NC 28120
175022
(Gaston County)Irrigation Approx. 1,975 West N/A N/A N/A
2 N/A Duke Energy Carolinas, LLC
(owner)
175 Steam Plant Road
Mount Holly, NC 28120
175033
(Gaston County)
Unknown (reported by
Duke Energy as may have
been used for drinking
water)
Approx. 1,750 Southwest N/A N/A N/A
3 N/A Eugenia and Robert White
(property owner)
4050 Neck Rd
Huntersville, NC 28078
1318106
(Mecklenburg County)Drinking Approx. 2,300 Northeast N/A N/A N/A
Notes:
1. Well locations are shown on Figure 1.
2. Owner and property address information for water supply wells was obtained from Gaston County's online database and Mecklenburg County's online Property Ownership and Land Records Information System (POLARIS).
3. Distances between water supply wells and the ash basin compliance boundary are approximate.
4. N/A indicates not available.
5. (ft-bgs) indicates feet below ground surface.
6. (gpm) indicates gallons per minute.
Reported Private Water Supply Wells
Public Water Supply Wells