NC0001422_SW Mitigation & Monitoring Plan_20150808

SOUTHERN ENVIRONMENTAL LAW CENTER
Telephone [phone] 601 WEST ROSEMARY STREET,SUITE 220 Facsimile 919-929-9421
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CHAPEL HILL,NC 27516-2356
August 5, 2015
VIA EMAIL AND U.S. MAIL RECEIVED!DENRIDWR
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Mr. S. Jay Zimmerman,Acting Director
DENR Division of Water Resources Water Quality
1617 Mail Service Center Permitting Sectior
Raleigh,N.C.,27699-1617
[e-mail]
Groundwater Mitigation and MonitoringPlan—Duke Energy,L.V. Sutton
Re: g
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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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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, •
Frank S. Holleman III
Senior Attorney
k)4j#` 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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