NC0001422_Sutton Accelerated Remediation Summary_20160502

L. V. Sutton Electric Plant
Proposed Accelerated Remediation for Offsite Groundwater Impacts
1.0 Background
A Notice of Regulatory Requirement (NORR) was issued by NCDENR on June 9, 2015 requiring Duke
Energy to take action to control and prevent further migration of coal ash contaminants along the east
side of the L.V. Sutton Plant (Sutton Plant). A Groundwater Mitigation and Monitoring Plan was submitted
to NCDENR on July 9, 2015 outlining the proposed plan to address the NORR. A Settlement Agreement
(Agreement) dated September 29, 2015 between NCDEQ (formerly known as NCDENR) and Duke
Energy requires Duke Energy to implement accelerated remediation along the eastern Sutton Plant
property boundary where data indicates ash basin related constituent concentrations above 2L Standards
have migrated off-site. As part of the Agreement, the NORR dated June 9, 2015 was withdrawn. The
Agreement requires Duke Energy to implement accelerated remediation at the Sutton Plant on the
following terms and conditions specifically related to the off-site groundwater impacts:
• Extraction wells will be used to pump groundwater to arrest the off-site extent of the migration.
• Groundwater will be pumped and treated as needed to meet regulatory standards and the treated
groundwater will be routed to the ash basin or the discharge canal.
• The extraction and treatment system will be installed as soon as practicable following receipt of
all permits and approvals from NCDEQ and is in addition to other Coal Ash Management Act
(CAMA) obligations.
• Extraction wells shall remain operational until it is demonstrated, subject to NCDEO's written
concurrence that off-site groundwater impacts have been remediated to 2L Standards and there
is no reasonable potential for future off-site migration.
2.0 Scooe
The following steps are recommended:
• Conduct an aquifer/pump test to evaluate site-specific physical properties of the aquifer and
obtain data for the extraction well system design. (Status —The 3 -day pump test is scheduled to
be completed in March 2016 pending receipt of permits.)
• Provide extraction and treatment system design to NCDEQ for review and approval.
• Due to NPDES Permit limits the construction of an ash basin dewatering treatment system is
required. (Status — Construction of the ash basin dewatering treatment system is currently
underway and expected to be completed later in 2016.)
• Potentially 1.3 MGD of groundwater could be generated from the proposed extraction system.
Treatment through the dewatering system is the most practical approach to handling extracted
groundwater.
In addition to the groundwater modeling required by CAMA, additional groundwater modeling simulations
using supplemental extraction wells may be pertormed to improve recovery of impacted groundwater near
the ash basins. These supplemental extraction wells would be located between the ash basin and the
east property boundary.
3.0 Challenges
Challenges include obtaining permits or modifications to existing permits and working in coordination with
other ongoing Site construction/remediation activities.
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L. V. Sutton Electric Plant
Proposed Accelerated Remediation for Offsite Groundwater Impacts
Permits required
• Schedule is dependent on ash basin dewatering treatment system
• Approval of action from NCDEQ DWR
• NCDEQ recovery well permits
• Erosion &Sediment Control permit
• Modification to the State Stormwater Permit (applies to coastal counties)
• Potential New Hanover County building/electrical permits (remediation compound)
Construction/Remediation System Challenges
• Working around landfill construction activities
• Working around ash loading activities
• Working around construction of dredging water treatment system
• Power to pumping system area
• Long term discharge location (Discharge canal, cooling pond or Cape Fear River)
4.0 Figure
Figure 1: Sutton Plant
February 17, 2016 2 of 3

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L. V. Sutton Electric Plant
Proposed Accelerated Remediation for Offsite Groundwater Impacts
5,0 Conceptual Schedule
Task Description
Estimated
Length of
Time
Estimated
Completion
Date
Aquifer Pump Test System Installation
1 week
3/14/16
Aquifer Test and Reporting
4 weeks
4/15!2016
Extraction System Engineering Design
6 weeks
5/27/2016
Extraction System NCDEQ Approval
6 weeks
7/8/2016
Extraction System Bidding/Contractor Selection
4 weeks
8/5/2016
Extraction System Installation
16 weeks
1 1125/2 0 1 6
Completion of Ash Basin Dewatering Treatment
System (currently underway)
48 weeks
12/4/2016
Extraction System Start Up and Testing
4 weeks
12/23/2016
Extraction System Certification Report (Final
Submittal to NCDEQ)
8 weeks
2/17/2017
February 17, 2016 3 of 3