NC0001422_Groundwater Mitigation_20150808

SOUTHERN ENVIRONMENTAL LAW CENTER
Telephone [phone] 601 WEST ROSEMARY STREET,SUITE 220 Facsimile 919-929-9421
CHAPEL HILL,NC 27516-2356
August 5,2015
VIA EMAIL AND U.S. MAIL RECEIVEDIDENRIDWR
- /015
Mr. S. Jay Zimmerman, Acting Director
DENR Division of Water Resources Water Quality
1617 Mail Service Center Permitting Sector
Raleigh,N.C.,27699-1617
[e-mail]
Re: Groundwater Mitigation and Monitoring Plan—Duke Energy,L.V. Sutton
Complex
Dear Mr. Zimmerman:
The Southern Environmental Law Center provides the following comments on Duke
Energy's proposed remedial plan for its groundwater contamination at its Sutton Plant near
Wilmington,N.C. The Department had previously required Duke Energy to submit a remedial
plan. The Center represents Cape Fear River Watch, Sierra Club, and Waterkeeper Alliance with
respect to the coal ash pollution at the Sutton Plant.
In several important respects,this plan is inadequate to address the groundwater
contamination at Sutton and fails to protect the public and the water resources of the State.
1. This plan does not contain sufficient information to design an adequate pumping
remediation system.
This plan was put together quickly. It is unlikely to be adequate to control contaminant
migration from the facility. Significantly more characterization, data evaluation, and a more
robust groundwater model will be needed to design and implement a remedy that can have a
chance of working.
2. The plan does not deal with groundwater flow in other directions—only on the
east side.
The plan acknowledges that there is radial groundwater flow(north, south, east, and
west) away from the ash management areas. That implies that the water level in the ash
impoundments is higher than beneath the surrounding areas. Installation of pumping wells along
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the east side of the impoundments will not do anything to control migration of boron, arsenic, or
other coal ash contaminants toward the north, south, or west.
3. The plan does not deal with the arsenic contamination from coal ash.
There are very high concentrations of both boron and arsenic in the groundwater at
Sutton,as shown by data from monitoring wells including MW-2 and MW-18 (arsenic up to 267
ug/L and 169 ug/L,respectively).1 Wells MW-2 and MW-18 are shown on the attached Catlin
Map(Attachment 1)but are not shown on the maps prepared by Geosyntec that are included in
this plan. This plan does not recognize the potential that the pumping will generate water
containing high arsenic levels along with the high boron. These findings are not surprising,
because arsenic is often found in high concentrations in ash leachate. At a minimum, the plan
should require monitoring of the discharge water for arsenic concentration and treatment to meet
effluent standards. Additional arsenic that has been absorbed onto sediments may be
remobilized when changes to the hydrogeology(like lowering water levels through pumping)
induce a slight change in the water chemistry. This could cause elevated arsenic to show up in
wells at some time after the initial start of pumping.
4. The monitoring plan should sample the wells for the entire suite of coal ash
pollutants at the site—including arsenic-and not just for boron.
The monitoring plan indicates that the wells will be sampled only for boron. The samples
should be analyzed for the entire suite of coal ash contaminants at this site, including arsenic,
hexavalent chromium, and vanadium. This list should also include molybdenum,which is often
found at sites with arsenic problems.
5. The polluted water should not be pumped back into the discharge canal and
thereby into Sutton Lake without treatment to remove pollutants,including
boron and arsenic.
This plan indicates that the polluted water—including high levels of boron and possibly
arsenic and other coal ash pollutants—will just be moved around; it will be pumped out of the
ground and then discharged back into Sutton Lake, a public fishing lake and a water of the U.S.
and of North Carolina. This is a plan just to move coal ash pollution from one public water
resource to another—from groundwater to a public fishing lake and thereby possibly to the Cape
Fear River and also back into the groundwater. This is a pollution shell game that moves coal
ash pollutants, including boron and arsenic, from one public water supply to another.
6. The plan does not define the vertical extent of coal ash contamination.
The plan admits a downward vertical gradient that would carry contaminants downward
as well as laterally away from the impoundments. The scant analytical model used in the plan to
estimate the pumping needed to contain the plume is a two-dimensional model that does not
DENR has posted the groundwater monitoring data for this site at http://portal.ncdenr.org/web/wq/hot-
topics/coalashregulation/gwatermonitoring,and we incorporate by reference the posted data,which as of the date of
this letter covers January 1980 to June 23,2015.
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consider the thickness of the contaminant plume. Contaminants may migrate below any
pumping wells that are installed, so that the pumping wells would not remove pollutants as they
are represented to do.
7. An inadequate model is used to estimate the number of wells and pumping rates
required to capture the plume.
This model is little more than a back-of-the-envelope calculation. The plan needs much
more detailed hydrogeologic characterization data upon which to base the well design. The plan
should be based on site-specific data showing:
a)how many and where the silt layers or other confining units are located,
b)what is the real site specific range of hydraulic conductivities,
c)what is the site specific gradient, and
d)what is the site specific aquifer thickness.
8. Piezometers outside of the extraction wells should be used to measure water
levels.
The Operation and Maintenance section of the plan indicates that water levels will be
measured in the extraction wells but does not mention measuring water levels in piezometers
located outside of the extraction wells. Measurement of head in existing wells located around the
site is not sufficient to evaluate the water elevation in the formation near the extraction wells.
Head measurements in extraction wells often show more drawdown than occurs in the formation
outside the wells. Water elevation measurements from piezometers located near the extraction
wells are needed in order to evaluate water levels in the surrounding formation as well as in the
extraction wells.
In summary,this is a plan based on inadequate information. Even if it worked as
designed,this plan would not correct the groundwater coal ash contamination at Sutton. The
plan does not control migration of coal ash polluted groundwater to the north, south, or west of
the impoundments. Discharging water with high amounts of boron and potentially arsenic, as
well as other coal ash constituents, into Sutton Lake only moves the coal ash pollution from one
place to another. And the monitoring systems do not test for the full range of coal ash pollutants,
including arsenic, and are inadequate to measure the plume of pollutants and the water levels as
the plan goes forward.
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Thank you for your consideration of these comments.
Sincerely,
E L0e110,,,,szcw
Frank S. Holleman III
Senior Attorney
k)1 I
Nicholas S. Torrey -
Staff Attorney
cc:
Jim Gregson, WQROS WiRO Supervisor
Sergei Chernikov,NPDES Permitting(#NC0001422)
Gina McCarthy, EPA Administrator
Heather McTeer Toney, Regional Adniinistrator, EPA Region 4
Mark J.Nuhfer, Chief, Municipal&Industrial NPDES Permitting,EPA
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