WQ0000020_Comments_20131104

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CENTRAL FILES
NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water Resources
Pat McCrory Thomas A. Reeder John E. Skvarla, III
Governor Director Secretary
October 23, 2013
John R. Toepfer, P.E.
Duke Energy Progress
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410 S. Wilmington Street/PEB14 Aquifer Protection Section
Raleigh, NC 27601
RE: Response to comments from Duke Energy Progress dated September 6, 2013
concerning the Asheville Airport Engineered Fill Project — Area III Development
Dear Mr. Toepfer:
The Asheville Regional Office of the Division of Water Resources (DWR) acknowledges receiving
a response to our review comments dated August 6, 2013. We have provided additional
questions and comments, in the bulleted paragraphs below. Please note that some comments
include requirements applicable to all structural fill areas at this site:
• CCP leachate in Area IV and possibly Area III is/will be pumped and hauled by VLS of
South Carolina to their industrial wastewater treatment plant located in Mauldin, SC.
DWR is requesting a letter from VLS of South Carolina specifically agreeing to accept the
CCP leachate and verification that they are authorized to operate an industrial
wastewater treatment facility. Please provide a total volume of CCP leachate that has
been pumped and hauled to date.
• The Metropolitan Sewerage District (MSD) of Buncome County recently issued an
industrial discharge permit to allow the CCP leachate to be discharged to their public
sewer system from both Area IV and Area III. Please provide a letter from MSD
specifically agreeing to accept the CCP leachate and a copy of the industrial discharge
authorization.
• In order for DWR to monitor the condition of the ash post -emplacement, please provide
all existing and future records pertaining to leachate water quality assessment,
discharge and disposal for all CCP fill areas. Please identify whether the leachate is
discharged to MSD (i.e., flow volume) or any pump and haul contractor. This data can be
WATER QUALITY REGIONAL OPERATIONS SECTION
North Carolina Division of Water Quality - Asheville Regional Office
2090 U.S. Highway 70, Swannanoa, N.C. 28778
Phone [phone]
FAX [phone]
Internet: h2o.enr.state.no.us
An Equal Opportunity/Af nnative Action Employer

Duke. Energy Progress'- Asheville
October 23, 2013
Page 2 of 3
submitted to DWR on the same schedule as the submittal of groundwater analytical
results.
• DWR had previously requested further explanation on the groundwater modeling
results, specifically those instances where the calculated 90% concentrations for several
analytes is higher at the compliance boundary as compared to the review boundary. The
explanation provided in Duke's September 16, 2013 response fails to satisfactorily
explain these calculations and therefore, a more detailed response or expanded
calculation is warranted. While DWR agrees that overall, the design of the ash
containment structure appears protective, it is difficult to ensure compliance with
permit condition 1.5 if the constituent concentrations as modeled indicate an increasing
trend away from the waste boundary. This is especially relevant in Area III where active
water supply wells are located within 300 feet of the structural fill. The DWR is
requesting a more detailed description of the model's 'prediction error' or alternatively,
further analysis that includes a greater number of realizations as your response
comment suggests.
• During the hydrologic investigation for Area III, thallium was detected in monitoring well
MW6 at a concentration above the standards found in NCAC 2L.0200. Duke's
September 16th response indicates that Pace Analytical Services, Inc. suggests that
chloride can interfere with thallium analysis thus implying that the interference can
result in a false positive result. However, other onsite monitoring wells had higher
chloride concentrations without detections of thallium. Please provide additional
documentation and explanation, if available, regarding all thallium detections.
• Our previous letter highlighted the need for an operation and maintenance plan for the
CCP structural fills as required by 15A NCAC 02T.1208. Your comments largely
addressed the institutional controls being put in place during the design and
construction phases. What is lacking is a concise understanding of the long-term
maintenance needs at all of the structural fill sites. Please provide a detailed 0&M plan
that outlines the post -construction care of the Asheville Airport structural fill project (all
areas). The plan should address the following topics:
1. Party responsible for long-term maintenance,
2. Inspection frequency and reporting for all CCP fill areas is to include, but not be
limited to: visual inspection of all slopes underlain by CCPs, monitoring well
structural integrity, drainage pathways, and cover crop. Report and repair any
signs of erosion and breaches in fill and liner, keep slopes clear of woody debris,
maintain drainage features, and maintain cover crop. Report any day -lighting of
CCPs. Report any planned construction activities that will occur atop areas filled
with CCPs prior to those activities.
3. Protection of liners during the runway expansion project; and,

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Duke Energy Progress - Asheville
October 23, 2013
Page 3 of 3
4. A quality assurance plan for groundwater monitoring.
• According to 15A NCAC 02T.1204, you are responsible for providing a site plan that
includes the location of all wells (including usage and construction details if available),
streams (ephemeral, intermittent, and perennial), springs, lakes, ponds, and other
surface drainage features within 500 ft. of the CCPs use boundary.
• DWR requested the relocation of monitoring wells MW3, MW4, and MW6. The new
locations for MW3 and MW6 are acceptable. The addition and location of MW7 is also
acceptable. It is understood that site conditions prevent the movement of MW4. The
current location of MW4 is acceptable.
Please contact me if you have any questions regarding our review comments. I can be reached
at [phone] [e-mail].
cc: Jon Risgaard —DWR Raleigh
Sincerely,
Br' tt Laverty
W ter CQualit
Ashe ' Re'a
Zegional Operations Section
nal Office