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Reporting period of 7-1-24 to 12-31-24.
Key Timelines/Milestones:
- November 11, 2024: During a routine walkthrough at the Cambridge Station at approximately 6:46 AM CST, an Enbridge employee noticed what appeared to be product staining on gravel near the Line 6 Unit 4 Discharge Valve outside of the Line 6 Pump House. The pipeline was immediately shut down and the facility isolated. The staining was confirmed to be a release of crude oil, and at 7:24 AM CST, the release was reported to the National Response Center (NRC; NRC Report No. 1416053) and subsequently to the Wisconsin Department of Natural Resources (WDNR). The WDNR assigned SERTS Spill ID No. 20241111SC28-1 within the hour.
- November 11, 2024: Immediate actions were initiated.
- November 11, 2024: The leak was identified at a below grade bolted flange connection on the Line 6 Unit 4 Discharge Valve (CB-6-UDV-41) and repair activities commenced.
- November 12, 2024: Repair activities were completed, and the Cambridge Station was returned to full service following a monitoring period.
- November 12, 2024: Immediate actions continued via the mechanical removal of impacted soil at the release location and adjacent areas. Soil screening and sampling activities were ongoing throughout the duration of mechanical remediation and immediate actions.
- November 15, 2024: Initial round of shallow groundwater sampling completed at the site’s four existing groundwater monitoring wells.
- November 21, 2024: Solid waste disposal approved at licensed disposal facility.
- November 22, 2024: Solid waste transportation and disposal activities commenced.
- November 26, 2024: Water sampling completed at the site’s potable water well.
- December 4, 2024: Round of surface water sampling conducted at an unnamed agricultural drainage ditch/stream located along the site’s eastern property boundary.
- December 9, 2024: Soil samples collected from the base of the primary release area excavation following the substantial completion of excavation activities.
- December 10, 2024: Under immediate actions, a soil and groundwater investigation was initiated to characterize potential impacts beyond the primary release area excavation.
- December 11, 2024: Liquid waste disposal was approved at licensed disposal facility.
- December 13, 2024: Off-site private potable water well sampling completed at two landowners’ properties.
- December 13, 2024: WDNR closed the SERTS Spill Activity case and transferred the site to the WDNR Environmental Repair Program.
- December 16, 2024: Primary release area excavation backfilling activities commenced.
- December 16, 2024: Installation of nine PVC monitoring stickup risers initiated in the primary release area excavation.
- December 16, 2024: Liquid waste transportation and disposal resulting from immediate actions was completed.
- December 19, 2024: WDNR assigned BRRTS Activity No. 02-28-595980 and Enbridge received a Responsible Party Letter.
- December 23, 2024: Solid waste transportation and disposal activities resulting from immediate actions were completed.
- December 23, 2024: Supplemental surface water sampling completed at the adjacent-east agricultural drainage ditch/stream.
- December 24, 2024: Enbridge submitted a 45-day Immediate Actions Report to the WDNR.
Planned/Ongoing Interim Activities (Quarter 1 2025):
- Interim sampling including:
o Onsite monitoring wells.
o Onsite potable water well.
o Onsite temporary monitoring wells.
- Interim sampling at off-site private potable water well(s).
- Interim/ongoing site monitoring including:
o Routine release area visual monitoring.
o Release area PVC riser stickup visual monitoring and gauging.
o Adjacent agricultural ditch/stream visual monitoring.
- Interim investigation at the site including west of the release location.
Planned/Ongoing Reporting (Quarter 1 2025):
- Formal Immediate/Interim Actions Report.
- Site Investigation Work Plan.
- Weekly email up
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