Roxboro_CoverLetterToSheliaHolman_20181115

DUKE
November 15, 2018
Ms. Sheila Holman
Assistant Secretary for Environment
North Carolina Department of Environmental Quality
1611 Mail Service Center
Raleigh, North Carolina 27699-1611
Paul Dreovitch
Senior Vice President
Envronanental, Health & Safety
526 S. Church Street
Mad Code., EC3XP
Chartotte, NC 28202
[phone]
Subject: Roxboro Steam Electric Plant ash basin closure options, groundwater modeling and
community impact analysis
Dear Ms. Holman:
Duke Energy is providing information in response to the North Carolina Department of
Environmental Quality's requests on September 13 and October 8, 2018, to submit preliminary
updates to the closure options analysis, groundwater modeling and community impact analysis
for the Roxboro Steam Electric Plant. These studies represent a key portion of the work the
company has performed to develop closure plans that balance a variety of considerations.
Duke Energy is committed to closing ash basins in ways that are safe, timely, environmentally
sound, and based on thorough science and engineering. In addition, effective closure plans are
site -specific and must ensure ash is managed in ways that continue to protect public health,
safety and the environment. Importantly, the planning process also considers how closure
choices may affect neighbors and communities.
After considering a number of potential closure options at Roxboro, three options were
advanced for detailed analysis for both ash basins: closure -in -place, closure -by -removal and
closure -in -place hybrid. Under all scenarios, the east ash basin and west ash basin extensions
will be excavated and placed inside the larger basins.
Based on a comprehensive assessment, Duke Energy will recommend at a later date either
closure -in -place or a hybrid closure plan to safely close the two Roxboro ash basins. We look
forward to input from regulators and interested stakeholders as we continue to evaluate safe
closure methods in a manner that protect people and the environment, while also minimizing
disruption to communities and managing cost.
North Carolina As a National Leader
To help ensure that the work done in North Carolina balances various considerations and
incorporates interdisciplinary perspectives, the company created the National Ash Management
Advisory Board (NAMAB) in 2014. This group of well -recognized experts in environmental
engineering, waste remediation, toxicology and other fields continues to provide ongoing
technical input and vet the various choices and tradeoffs inherent to any closure plan.
As previously stated, the enclosed documents represent key elements among the extensive
science and engineering being conducted by dedicated teams at Duke Energy and outside

experts, with ongoing input from NAMAB, to identify safe and smart basin closure plans for
remaining sites in North Carolina.
Groundwater Modeling
As multiple sources have validated, ash basins have not affected neighbors' drinking water
wells near the Roxboro Plant. For communities concerned that nearby well water could be
affected in the future, state lawmakers in 2016 passed legislation requiring the company to
proactively provide permanent drinking water sources. The company has completed the
installation of advanced, whole -home filtration systems for neighbors within a half -mile of the
Roxboro basins, even though evidence demonstrates that ash basins are not impacting them,
and most neighbors' well water already met the appropriate performance standards for the filter
systems.
In addition to advanced planning for safe drinking water, the N.C. Coal Ash Management Act
(CAMA) outlines an elaborate process to monitor and study groundwater near ash basins. This
involves thousands of monitoring wells across the state and using those real -world data points
to develop site -specific models that seek to predict how groundwater will respond to various
closure scenarios. This process also involves several iterations of extensive groundwater
studies and developing proposed corrective action steps that will work in tandem with basin
closure as necessary to address groundwater impacts.
Based on extensive study, the company understands that groundwater at Roxboro moves
slowly and that coal ash impacts are very localized near the ash basins and generally on plant
property. In any closure scenario, the most effective step the company can take to improve
groundwater is to safely remove the free water from the ash basins. When predicting future
groundwater response at Roxboro, the models demonstrate that:
• The patterns of decreasing boron concentration in the three closure scenarios at the
east and west ash basins are generally similar for decades. Beyond 2330, the
groundwater impact appears to resolve slightly more quickly in the closure -by -removal
scenarios.
• The simulations indicate there will continue to be no impact to drinking water wells.
Groundwater impacts will continue to be evaluated as the updated modeling expands to other
parameters.
The models do not include the effects of any additional groundwater remediation steps the
company may take in the future. As part of a separate state -directed process, the company will
submit corrective action plans that propose steps that can be taken where groundwater
necessitates additional or more timely improvement. In particular, the company will pursue
groundwater remedial actions where needed with a focus on any surface water or offsite
property impacts.
Community Impact Analysis
In addition to relying on strong science and engineering, the company felt it was important to
consider various stakeholder interests and community impacts when developing its

recommended ash basin closure plans. In addition to its own research, which is included in the
comprehensive options analysis, the company relied on an outside consulting firm, Exponent, to
study the potential community impacts of various closure scenarios. Key take-aways include:
• All closure options evaluated would be protective of human and ecological health.
• Closure -in -place and hybrid closure options create less local community disturbance.
The community disturbance caused in the closure -by -removal scenario (noise and
traffic) would be both longer and more significant.
• Closure -in -place would cause a net loss in ecological services (protection of biodiversity
and natural beauty), because a grass cap is less valuable habitat than open fields,
wetlands or forested areas. Any net loss in ecological services resulting from closure -in -
place can be offset by reforestation of land parcels.
The community impact analysis does not compare greenhouse gas emissions from offsite and
offsite trucking activity; therefore, a supplemental analysis will be provided comparing the
impact of various closure options on greenhouse gases and other air emissions.
The results of the community impact analysis vary by site, but in all cases cap -in -place closure
may be performed without adversely impacting the community. In some cases, reforestation of
land parcels may be advisable to offset any net habitat losses.
The conclusions in the community impact analysis are subject to revision if new landfill space
must be created to accommodate production ash. In such circumstances, excavation options
would score lower in the community impact analysis.
Options Analysis
The company's options analysis considers the many aspects and tradeoffs related to basin
closure including environmental protection, schedule and the company's own analysis of
community impacts. In addition, as a regulated utility, Duke Energy is obligated to evaluate the
cost-effectiveness of the closure options. The company developed a relative weighting and
scoring system with input from the NAMAB that was used to evaluate and score various closure
alternatives.
For Roxboro, key take-aways from the options analysis include:
The capping design is the least -cost option, with the hybrid approach substantially
higher. For the west ash basin, closure -by -removal is expected to cost four times more
than closure -in -place. For the east ash basin, closure -by -removal is expected to be
seven times more expensive than closure -in -place.
The closure -in -place and hybrid options do not involve ash transportation on public
roads; however, the closure -by -removal options require relocating more than 13 million
cubic yards of material from the west basin and 3.4 million cubic yards of material from
the east ash basin to the Mayo landfill more than 15 miles away. This would involve
hundreds of truck trips daily on local roads.

• Closure -in -place for both basins can be completed in the shortest time frame and meet
the CAMA deadline of 2029. The hybrid options could be challenging to complete by
2029. Closure -by -removal for both basins would take up to 16 years, exceeding the
2029 CAMA deadline and the latest federal Coal Combustion Residuals (CCR) rule
deadline of 2034.
Another option currently is being evaluated for Roxboro. This includes an excavation scenario
that removes the current overfill landfill and relocates all material to a new on -site landfill south
of the east ash basin or west of the west ash basin. The analysis of its feasibility will be provided
in a subsequent update. It is expected to show that, if site conditions are suitable and the
assumed landfill can be sited and permitted, it is a more favorable option than removal and
transport to the Mayo landfill 15 miles away; however, is not expected to displace closure -in -
place as the highest scoring option.
The company's recommended closure approach across its North Carolina sites reflects a
science -based combination of excavating, capping in place and recycling ash for concrete and
other beneficial purposes. Duke Energy remains committed to safely closing ash basins and
welcomes input from DEQ and the public to best balance these various tradeoffs.
Sincer ly,
Paul DraovitOf
Senior Vick President
Environmental, Health & Safety
cc: Jim Wells, Duke Energy
Dave Renner, Duke Energy
Randy Hart, Duke Energy
Ed Mussler, DW M
Jon Risgaard, DWR
Andrew Brooks, DEMLR
Bill Lane, NCDEQ General Counsel
4