1812_DukeMarshall_AugustUpdate_FID_20220818

Duke Energy Carolinas LLC, Marshall Steam Station
August 18, 2022
NCDEQ Division of Waste Management (DWM) Solid Waste Section Marshall Steam Station Monthly Update
July 21 through August 18, 2022
Below is the monthly summary for Marshall Steam Station Solid Waste facility and project activities, regulatory submittals and
approvals, and upcoming items.
Facility and Project Activities:
• General:
• The 2022 Solid Waste Facility Annual Inspection onsite visit was completed on July 22, 2022.
• Dry Ash Landfill (1804-INDUS-1983):
• The second 2022 semiannual monitoring event for the Dry Ash Landfill was completed on August 8, 2022, and
August 10, 2022. The semiannual monitoring report will be submitted within 120 days from the monitoring event,
by December 8, 2022.
Phase I:
• Area has been stabilized. It is proposed to continue excavating soil from below the final CCR excavation
elevation down to the approximate final grades in the Application for Permit Modification - Closure by
Excavation. The excavated soil would be used as an onsite soil resource for construction projects as needed.
If soil is proposed to be stockpiled outside of the landfill or ash basin, used outside of a liner system, or used
above a geosynthetic cap, DWM would be consulted prior to moving soil.
Phase II:
• Redesign of the Closure Plan's original design for including the balanced cut slope stability feature design at
the southern ash basin finger is expected to be submitted by mid -October 2022.
• FGD Landfill (1809-INDUS-2006):
• No general facility updates.
Industrial Landfill No.1 (1812-INDUS-2008):
• The second 2022 semiannual monitoring event for the Industrial Landfill No.1 was completed on August 10, 2022.
The semiannual monitoring report will be submitted within 120 days from the monitoring event, by December 8,
2022.
• Normal operations for Phase 1. Placement of CCR material continues across the active face of Cells 1 through 4.
The landfill is primarily receiving production CCR material.
• Water levels in 21 piezometers and groundwater monitoring wells in the ILF area continue to be monitored.
o The next manual water level measurements were collected the week of August 8, 2022. Water level data will
be provided in the next monthly update. Transducers continue to record data at 1-hr to 4-hr intervals.
ILF Phase 2, Cell 5:
• Installation of the geosynthetics through the primary geomembrane is complete.
• Continued work to install LCS/LDS and underdrain riser pad, and electrical components.
• The blanket underdrain is operational with a temporary pump. Pumping is occurring at an average flowrate of
approximately 9 gallons per minute (based on available June flow rate data). The temporary pump is expected
to be replaced in September 2022.
ILF Phase 2, Cell 6:
• Fine grading of the subgrade nearly complete. Observation of the subgrade for any pertinent geological
features completed on August 10, 2022 (report to follow). No issues with groundwater have been encountered
to date while working on the subgrade for Cell 6.
• Compacted soil liner test pad completed. Compacted soil liner installation anticipated to start within the next
few weeks.
• Dewatering in the former ash basin finger within the footprint of Cell 6 is being maintained, with an average
flowrate of approximately 11 gallons per minute (based on available June flow rate data).
ILF Future Phases Area:
• Excavation of CCR in the future phases is ongoing, with CCR from this area being used to pad out into the
main pond area to support closure.
• Dewatering continues with an average flowrate of approximately 90 gallons per minute (based on available
June flow rate data).
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Duke Energy Carolinas LLC, Marshall Steam Station
August 18, 2022
• Leachate Basin:
• No general updates.
• Structural Fill (CCB0031):
• Continued placing and compacting soil on the top deck and maintenance of E&SC measures.
• Stability Features (Structural Fill and 1804 Phase 11):
• A response to comments from NCDEQ on the Conceptual Design Report are in progress. The detailed design
package is anticipated to be submitted in September 2022.
• Vibrating wire piezometers are routinely being monitored during the design period.
• Other Ash Basin Closure Projects:
• Continued ash basin dewatering, with current elevation of the pond at approximately 775 NAVD 88.
• Excavation of CCR from the ash basin finger southeast of the Structural Fill (CCB0031) is ongoing, with CCR
from this area being used to pad out into the main pond area to support closure.
Regulatory:
• On July 29, 2022, Duke Energy submitted the ILF Q1 2022 Groundwater Conditions Report.
• On July 26, 2022, DWM provided a response for Cell 5 construction certification report Volume 1 (Earthworks) and
Volume 2 (Geosynthetic Liner System), indicating there were no comments to date.
• On July 29, 2022, Duke Energy submitted the FY2021-22 CCR Basin Management Report.
• On August 5, 2022, Duke Energy submitted the FY2021-22 Annual Solid Waste Management Report for Permit No.
1812-I N D U S-2008.
• On August 9, 2022, Duke Energy submitted the ILF Phase 2, Cell 6 revised Groundwater Vertical Separation
documentation.
• On August 10, 2022, DWM provided approval of the ILF Phase 2, Cell 6 revised Groundwater Vertical Separation
documentation.
Upcoming:
• The Geologic Subgrade Observation Report for ILF Phase 2, Cell 6 is expected to be submitted in August 2022.
• The Dry Ash Landfill Phase 1 soil sample results for total metals and SPLP is expected to be submitted in August
2022.
• The Stability Feature Engineering Design Report is expected to be submitted by September 2, 2022.
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