1812__DukeMarshall_BiweeklyUpdate_FID1629877_20220106

Duke Energy Carolinas LLC, Marshall Steam Station
January 6, 2022
NCDEQ Division of Waste Management (DWM) Solid Waste Section Marshall Steam Station Bi-Weekly Update
December 24, 2021 through January 6, 2022
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:
• Disposal of a small amount of demolition waste material in 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 Based on data through 12/3/21 (the last monthly collection of data, and at the time a total of 26 monitoring
locations) groundwater conditions generally continue to follow model predictions.
o A majority of the locations (20 of 26) indicate decreasing water level trends.
■ 9 of 20 wells with decreasing water level trends match model predictions.
■ 11 of 20 wells with decreasing water level trends appear to be decreasing at a faster rate
than model predictions.
o Four of the locations (4 of 26) indicate stable water level trends.
■ CLF21-10 has a stable water level trend that matches model predictions.
■ CLF21-18, CLF21-19, CLF21-20 have stable water level trends but were not included in the
original model calibration.
o Two of the locations (2 or 26) indicate slightly increasing water level trends.
■ ILF-2S/D have displayed a slight increase, differing from model predictions.
o The next monthly manual water level measurements and transducer data downloads will be collected
January,7 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.
• Installation of CSL continues in the north and east portions of the subgrade. FOR approved entire subgrade
(including west and south portions). Started work on perimeter ditch on the west side. Rain from earlier this
week has slowed progress overall.
ILF Phase 2, Cell 6:
• 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.
• Continued excavation, with the approximately 322,100 CY of CCR excavated to date. The estimated total
CCR to be excavated from this area is 1.5M CY.
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Duke Energy Carolinas LLC, Marshall Steam Station
January 6, 2022
• Dewatering during excavation continues with an average flowrate of approximately 60 gallons per minute.
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 late January 2022, after contractors' complete installation of E&SC
measures in the MAR-145 pond.
• Leachate Basin:
• Concrete formwork for basin floor continues and is expected to be completed early 2022.
• 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 70,800 CY of CCR excavated to date.
Regulatory:
• On December 29, 2021 Duke Energy submitted the voluntary Regional Recharge Trend Evaluation.
• On January 4, 2022 Duke Energy submitted the FGD Landfill Semiannual Groundwater Report and EDD for the
September 2021 semiannual sampling event.
Upcoming:
• 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.
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