WSRO Techncial Direction and Action Items 7-14-17

Water Resources
Environmental Quality
July 14, 2017
Ed Sullivan
Duke Energy
526 South Church Street
Mail Code EC13K
Charlotte, North Carolina 28202
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. JAY ZIMMERMAN
Director
Subject: Technical Direction and Action Items, Winston Salem Regional Office Meeting
May 18, 2017
Dear Mr. Sullivan:
On June 6, 2017, the North Carolina Department of Environmental Quality's Division of Water
Resources (Division) received the meeting minutes from the May 18, 2017 Winston-Salem
Regional Office Meeting. As part of the process agreed upon to facilitate completion of the site
assessments and corrective action plans, the Division provides the following summary of technical
direction and action items discussed during the meeting:
• Program -wide Issues
o Concerning the possible schedule for delivery of comprehensive site assessments
(CSAs) and corrective action plans (CAPs), Group 1 sites were proposed based on
the relative lack of remaining data gaps; also, ongoing litigation was considered
when identifying sites as Group 1, 2, or 3.
o Additional assessments that are deemed critical to complete CSAs must be
included in the revised CSAs; otherwise, additional source area assessments could
be conducted and reported under a separate pathway.
o Corrective action can vary across a site; monitored natural attenuation (MNA)
may be approved for certain areas of a site while other areas may warrant active
remediation.
o If there are surface water standard violations due to groundwater discharge, the
Division indicated it may not be able to approve a CAP that proposes MNA as the
corrective action.
o The Division may request additional surface water sampling at some sites since
MNA cannot be approved if 2B surface water violations exist.
State of North Carolina I Environmental Quality I Division of Water Resources
Water Quality Regional operations Section
1636 Mail Service Center I Raleigh, North Carolina 27699-1636
919-707-9129

o The Division will not consider surface water samples collected from mid -stream
locations for assessing unpermitted discharges — samples must be collected from
along the edge of the bank.
o The Division has concerns regarding monitoring wells that have exhibited
elevated pH and turbidity. Duke Energy is expected to address related issues to
provide defensible, representative data.
o Duke Energy should provide plans to address background data gaps or
acknowledge status of efforts to address this issue.
o The Division's Winston-Salem Regional Office (WSRO) is generally comfortable
with the status of assessments at the Belews Creek Steam Station, Dan River
Steam Station and Riverbend Steam Station;
o The group discussed and understood that CAPs would be due 180 days after
NCDEQ review and approval of CSA reports. NCDEQ estimated 90 days to
review and approve of CSA reports; thus, CAPS would generally be due 270 days
after submittal of CSAs
• Background Statistics
o For Chromium, Duke Energy should be using the Total Chromium Standard for
compliance (10ug/1). The Division may consider developing a Hexavalent
Chromium Standard based on ongoing evaluations by USEPA. However, Duke
will need to continue taking samples of Hexavalent Chromium so when EPA
develops a standard, data will be available. The Standard for Total Chromium
may or may not be decreased, but these evaluations would not be completed in
time to be applied to CSA and CAP work.
o The Interim Maximum Allowable Concentration (IMAC)for Vanadium should be
used for compliance (.3ug/1), although it may be changed to 10 ug/1 by the EMC.
If there were no 2L standard or IMAC, then the Practical Quantitation Limit
(PQL) would be used. There has been some discussion whether the Vanadium
IMAC is out of date. However, it is the Division's position that the IMAC should
continue to be used until it is revised or put into rule.
o The Division recommends developing multiple lines of evidence to determine
whether groundwater has been impacted by coal ash constituents in combination
with preliminary background threshold determinations to evaluate site
conditions. It is suggested to review EPRI's "Groundwater Quality Signatures for
Assessing Potential Impacts from Coal Combustion Product Leachate" document
(2012) to identify techniques for data analysis that would refine the delineation of
coal ash constituents in groundwater. This strategy would help better understand
spatially inconsistent exceedances of constituents such as hexavalent chromium
and vanadium at sites.
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• Belews Creek Basis of Design Report (60% Draft) for Interim Action
o The Division has concerns that proposed interim action of groundwater extraction
and discharge to the ash basin may not remediate the groundwater since there is
no treatment.
o There is consensus among Duke Energy and the Division that the intent of the
Interim Action is to comply with a settlement agreement to take immediate action
to reduce the flow of impacted groundwater onto an adjacent property not owned
by Duke Energy. Duke Energy is seeking to exhibit hydraulic control on
groundwater in this area, not treat the extracted groundwater.
o Boundary control should result from the proposed interim action pumping
operations that would meet the main objective of the proposed interim action.
o Due to the heterogeneity of the transition zone, the actual sustainable pumping
rates will need to be evaluated once the initial phase of the extraction system is in
operation. Following a six-month evaluation period, additional extraction wells
will be installed as needed and the model will be modified to better match actual
site conditions.
Action Items
• Belews Creek Steam Station
o One (1) additional shallow well west of GWA-19 is needed to complete
horizontal delineation in this area.
o Additional surface water samples within the Dan River and upstream of the S-2
area of wetness (AOW) sample location are needed to evaluate background
surface water quality.
o One (1) surface water sample should be collected from S-2 tributary adjacent to
the GWA-19 well location.
o Additional near -shore surface water sample(s) should be collected within Belews
Lake east of AOW, sample S-6. If the initial sample is impacted, two additional
samples should be collected in coves north and south of initial sample location.
o A table that identifies the constituent of interest (COI) concentrations used in the
Groundwater -Surface Water model is requested.
o In addition to groundwater discharge, contributions from permitted discharge
should be considered when running Groundwater -Surface Water model to
numerically determine or predict whether the Dan River is or will be impacted.
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• Dan River Steam Station
o The coal pile will not be assessed in conjunction with the CSA. No evidence of
coal -ash related impacts from the coal pile have been observed in soil borings or
monitoring wells completed during the CSA.
o Although GWA-12 wells are installed in a gravel parking lot, which could
account for presence of gray material encountered during drilling, and coal ash
was not observed near the GWA-12 wells, related data cannot be considered for
use in determining background concentrations because boron was detected in soil
samples collected from the boring.
o An additional bedrock well west of Ash Storage 2 and north of the coal pile
would be preferred to complete the site assessment, but would not negate
approval of the CSA report at this time.
o A table that identifies the COI concentrations used in the GW-S W model is
requested.
• Riverbend Steam Station
o An additional surface water sample in Mountain Island Lake should be collected
upstream of the site.
o A table that identifies the COI concentrations used in the GW-SW model is
requested.
If you have any questions, please feel free to contact Shuying Wang, the Winston-Salem Regional
Office, at [phone] or Steve Lanter at [phone].
Sincerely,
/Jonsgaard, Chief
Water Quality Regional Operations Section
Division of Water Resources
cc: Sherri Knight — WSRO Regional Office Supervisor
WQROS Central File Copy
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