1812_DukeMarshall_BiweeklyUpdate_FID1628537_20211223

Duke Energy Carolinas LLC, Marshall Steam Station
December 23, 2021
NCDEQ Division of Waste Management (DWM) Solid Waste Section Marshall Steam Station Bi-Weekly Update
December 10 through December 23, 2021
Below is the bi-weekly summary for Marshall Steam Station Solid Waste facility and project activities, regulatory submittals
and approvals, and upcoming items.
Facility and Project Activities:
• General:
• No general Site updates.
• Dry Ash Landfill (1804-INDUS-1983):
• No general facility updates.
Phase I:
• During final stages of excavation demolition waste material (concrete, drums, cables, etc.) was discovered.
Some of the larger pieces of the demolition waste material is to be disposed of in an off -site landfill, and less
than 100 tons of smaller pieces of the demolition waste material will be disposed of onsite in Phase 1, Cells 3
and 4 of the Industrial Landfill No.1 following the procedures in the Operations Plan for non -ash waste
placement.
• Confirmatory PLM sampling will begin, following disposal of all non -ash, demolition waste material.
Phase II:
• The Dry Ash Landfill Phase II Application for Permit Modification -Amended Closure Plan was submitted to
DWM on 8/30/21. Redesign of the Closure Plan's original design are in progress for the including the
balanced cut slope stability feature design at the southern ash basin finger.
• FGD Landfill (1809-INDUS-2006):
• No facility updates.
• Industrial Landfill No.1 (1812-INDUS-2008
• Normal operations for Phase 1.
• Water levels in 18 piezometers and groundwater monitoring wells in the ILF area continue to be monitored.
o The next monthly manual water level measurements will be collected the first week of January 2022.
Transducers continue to record data at 1-hr to 4-hr intervals.
ILF Phase 2, Cell 5:
• The blanket underdrain is operational with a temporary pump. Pumping is occurring at an average flowrate of
approximately 8.5 gallons per minute.
• South and west portions of the subgrade completed. Installation of CSL continues in the north and east
portions of the subgrade. Phase 1, Cell 4 to Phase 2, Cell 5 liner tie-ins exposed.
ILF Phase 2, Cell 6:
• Results of confirmatory soil samples from the former ash basin finger within the footprint contained less than
1% CCR material, considered a Non -Detect by the PLM Method.
• Construction and installation of the subgrade and southern embankment.
• Dewatering in the former ash basin finger within the footprint of Cell 6 is being maintained, with an average
flowrate of approximately 5 gallons per minute.
ILF Future Phases Area:
• Continued tree clearing and grubbing operations in the future Phase 3 area for continued excavation.
• Results of confirmatory soil samples collected the week of 11/29/21, from the former ash basin finger within
the future Phase 3 footprint contained less than 1 % CCR material, considered a Non -Detect by the PLM
Method.
• Continued excavation, with the approximately 312,950 CY of CCR excavated to date. The estimated total
CCR to be excavated from this area is 1.5M CY.
• Dewatering during excavation continues with an average flowrate of approximately 50 gallons per minute.
www.duke-energy.com Page 1 of 2

Duke Energy Carolinas LLC, Marshall Steam Station
December 23, 2021
Structural Fill (CCB0031):
• The Structural Fill Application for Permit Modification - Amended Closure Plan Response to Comments was
submitted to DWM on 8/19/21. Redesign of the Closure Plan's original design are in progress for the including the
balanced cut slope stability feature design at the northern ash basin finger.
• The new onsite soil borrow area to support the capping of the Structural Fill continues to be prepped with E&SC
measures and clearing and grubbing. The borrow area is expected to start being developed with placement of soil
on the top deck of the Structural Fill by January 2022. Demolition of photovoltaic concrete footers started.
• Leachate Basin:
• Concrete formwork for basin floor continues and is expected to be completed early 2022.
• MAR-152 Stormwater Redirect Project:
• The pump system is active; project completed.
• Started tying in the MAR-152 access road to the ILF Phase 2, Cell 6 perimeter road.
• Other Ash Basin Closure Projects:
• Continued ash basin dewatering, with current elevation of the pond at approximately 775 NAVD 88.
• Excavation of CCR continues in Area 3 of the ash basin [ash basin finger southeast of the Structural Fill
(CCB0031)] with the approximately 66,000 CY of CCR excavated to date.
Regulatory:
• On December 13, 2021 Duke Energy submitted CCR visual verification documentation and PLM results for the ash
basin finger south of ILF Phase 2, Cell 6.
• On December 13, 2021 Duke Energy submitted the updated Industrial Landfill No.1 ECMP (Rev 2), to include the
Cell 5 underdrain sample location.
• On December 14, 2021 DWM provided a letter approving the update Industrial Landfill No.1 ECMP (Rev 2).
• On December 20, 2021 Duke Energy submitted abandonment records and certification for seven piezometers
CLF21-17, CLF21-18, CLF21-19, CLF21-20, CLF-302, CLF-403, and CLF-404.
Upcoming:
• The voluntary Regional Recharge Trend Evaluation will be submitted by the end of December 2021.
• The FGD Landfill Semiannual Groundwater Report for the September 2021 semiannual sampling event will be
submitted by January 26, 2022.
• The Q4 2021 Groundwater Conditions Quarterly Report for the Industrial Landfill No.1 will be submitted by February
1, 2021.
• A demonstration of groundwater separation for ILF Phase 2, Cell 6 will be submitted in Q1 2022.
www.duke-energy.com Page 2 of 2