HomeMy WebLinkAbout7305_DukeMayo LF Environmental Event ReportMayo Monofill - Solid Waste Reporting Page 1 of 8
Solid Waste Environmental Event Reporting
Event Title: Subsurface Investigation / Leachate System Integrity
Report Date: April 20, 2018
Submitted to: NCDEQ Division of Waste Management (DWM)
Regulatory agency contact: Shawn McKee 919-707-8284
Duke Energy contact: Kimberlee Witt 336-215-4576
Duke Energy Facility: Mayo Steam Electric Plant
10660 Boston Road
Roxboro, NC 27574
Person County
Permit No.:7305-INDUS
1. Event Description
a. Date: 10/2016 CCR groundwater data was validated and confirmed that additional
investigation for exceedances in areas near the monofill were necessary
b. Material released
(Yes/No). Description if yes: potential leachate from lift station vault
c. Summary:
• Initial CCR sampling data identified subsurface areas that required additional investigation (10/2016)
• Leachate system pressure testing and vault inspections revealed potential leaks at:
o HDPE pipe penetration to wet vault at leachate transfer area; and
o force main line from leachate transfer station to FGD pond (from primary pipe, secondary containment pipe appears unaffected)
d. Field actions to date:
• 10/6/2016 Duke investigation team site visit
• 10/17/2016 Truck wash removed from service
• 11/2016 Leachate force main pressure line testing
• 11/2016 Truck wash tank integrity test
• 7/10/2017 - 7/13/2017 Leachate force main pressure testing from sump to transfer
area
• 7/12/2017 - 7/13/2017 Transfer area vault testing with transducers
• 2/2017 Excavation of the blind flange at the end of the leachate line run down past
the monofill sump area to verify integrity
• 4/2017 - 5/2017 Truck wash improvements installed (received approval from DWM)
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• 6/30/2017 Improved truck wash placed in service
• 8/2017 - 10/2017 Groundwater assessment wells installed
• 12/18/2017 - 12/20/2017 Groundwater assessment well sampling Round 1
• 12/21/2017 Leachate force main pressure testing from leachate transfer area to FGD
pond
• 12/2017 Re-torque all leachate force main accessible bolted connections and
installed isolation valves at the air release valves on the force main (received
approval from DWM for valve installation)
• 1/10/2018 - 1/11/2018 Leachate force main pressure testing of the line near the
transfer station valve vault and from the monofill sump to the leachate transfer
station
• 2/20/2018 - 2/21/2018 Groundwater assessment well sampling Round 2
• 3/13/2018 Visual inspection of the leachate transfer area vaults
• 3/19/2018 - 3/23/2018 Leachate force main pressure testing from leachate transfer
area to FGD pond and leachate lines between leachate transfer area vaults
• 3/20/2018 - 3/28/2018 Improvements/preventative repairs to the side slope riser headwork system to address potential leakage vulnerabilities due to freezing, water
hammer, or leaking connections in addition to secondary containment improvements in this area (received approval from DWM)
• 3/21/2018 During pressure testing, the leachate force main from leachate transfer area to FGD Pond was identified as having a potential integrity issue; line taken out of service; remains out of service as of the date of this report
• 3/29/2018 Leachate line between the transfer station vaults was identified as having a potential integrity issue; line taken out of service; remains out of service as of the
date of this report
• 3/29/2018 Blind flange installed on leachate transfer area line in order to operate the
force main at a reduced pressure rating (received approval from DWM)
• 4/2/2018 Began leachate hauling by truck (received approval from DWM)
• 4/4/2018 Began hydro excavation around leachate transfer station vaults and piping (notified DWM)
• 4/5/2018 Potential seal failure in the HDPE penetration to leachate transfer area lift station vault identified during hydro excavation
• Ongoing - development of engineering plans to identify force main areas of integrity loss; development of engineering plans for replacement of portions of the leachate
force main and leachate system
2. Regulatory Contact
a. Date and time of regulatory contact:
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Regulatory agency: NCDEQ Division of Waste Management (DWM)
Contact name/number: Primary - Elizabeth Werner 919-707-8253
Summary:
Phone conversations describing recent CCR results in wells near the monofill and
need for investigation.
• 10/4/2016 initial contact made with DWM hydrogeologist
• 1/31/2017 assessment Work Plan submitted to DWM, revised 2/23/2017
• 3/22/2017 assessment Work Plan approved by DWM
• 6/8/2017 provided face to face update on CCR data and assessment status
Regulatory agency: NCDEQ Division of Waste Management (DWM)
Contact name/number: Primary - Shawn McKee 919-707-8284
• 3/29/2018 conference call with DWM to update on assessment and recent findings
Summary:
Phone conversation describing recent findings and events regarding the leachate
line investigation for the groundwater assessment in addition to the leachate force
main potentially had two areas where integrity issues were identified.
• 4/5/2018 conference call with DWM to update on assessment and recent activities
Summary:
Phone conversation update of findings and events regarding the leachate line
investigation for the groundwater assessment in addition to the leachate force main.
A site inspection was set up for 4/9/2018 but rescheduled for 4/12/2018 due to
weather conditions.
b. Date and time of additional regulatory agency contact:
Regulatory agency: NCDEQ Division of Water Resources NPDES Section
Contact name: Vanessa Manuel contacted by Lori Tollie (Duke)
• 3/29/2018 at approximately 10:30am
Summary:
Phone conversation to report that the leachate force main potentially had two areas
where integrity issues were identified in addition to the historical investigation and
upcoming DWM site visit.
3. Regulatory Site Visit
Was a regulatory visit conducted (Yes/No)
a. Date and time of site visit:
April 12, 2018 arrival time:1:30pm, departure time: ~3:15pm
b. Regulatory agency: NCDEQ DWM
c. Attendees: Shawn McKee, Elizabeth Werner, Shannon Aufman
d. Duke Energy escort(s):Kimberlee Witt, Cedric Fairbanks, Michael Lazar
e. Areas inspected:
• leachate transfer area
• leachate sump area
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• FGD Pond
• future Waste Water Treatment (WWT) Pond construction area
• Lined Retention Basin (LRB) construction area
f. Records reviewed: None
g. Issues indicated: concern was expressed by the DWM regarding the ability to isolate
long leachate force main runs for testing and isolation when potential issues arose;
concern was expressed by the division regarding excessive head on the monofill liner.
4. Regulatory Recommendations:
• Submit a written report summarizing the events to date
• Follow up with the DWM regarding path forward once there is a defined scope
5. Duke Energy Follow-Up Actions:
• Submit Solid Waste Environmental Report to DWM by 4/20/2018
• Revise this report as additional information becomes available
6. Photos:
(include description with each photo)
Photo 1 - Truck wash area prior to improvements
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Photo 2 - Truck wash area after improvements
Photo 2 - _Typical Mayo monofill leachate force main pressure testing set up
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Photo 3 - Leachate transfer area prior to hydro excavation (two vaults)
Photo 4 - Leachate transfer area vault during leak testing
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Photo 5 - Leachate transfer area between vaults during hydro excavation
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Photo 6 - Leachate transfer area pipes revealed during hydro excavation (potential grout
integrity issue where HDPE pipes enter the vault)
cc: Ed Mussler - NDEQ DWM
Shannon Aufman - NCDEQ DWM
Elizabeth Werner - NCDEQ DWM
Ed Sullivan - Duke Energy
Leanne Wilson - Duke Energy
Cedric Fairbanks - Duke Energy
Michael Lazar - Duke Energy