Enbridge Energy Partners, headquartered in Houston, TX, transports crude oil, liquid petroleum, and natural gas in the Mid-Continent and Gulf Coast regions of the United States. The 4,700 mile Lakehead System transports crude oil through Canada and the upper Midwestern US. The 1,900 mile US portion of the Lakehead System includes Line 6B.

On July 26, 2010, the Enbridge control center in Edmonton, Alberta, Canada discovered a crude oil leak from Line 6B at 9:45 am local time, 11:45 am eastern daylight time. This 30 inch diameter pipeline transports crude oil and liquid petroleum products from Griffith, Indiana to Sarnia, Ontario, Canada. Enbridge reported the leak to the National Response Center at 1:33 pm eastern daylight time and estimated the spill volume at 19,500 barrels, equivalent to 819,000 gallons. At the time of the report, spilled crude oil had flowed through Talmedge Creek to the Kalamazoo River.

Enbridge isolated the leak by closing mainline valves upstream and downstream from the spill site to limit the volume of crude oil that could potentially leak from the pipeline. Oil containment booms were deployed on both Talmedge Creek and the Kalamazoo River. Also, Enbridge excavated the spill site to extract the oil as it leaked from the pipe. The federal Environmental Protection Agency (EPA) directed and monitored all aspects of oil spill cleanup and containment efforts for over 30 miles of the Kalamazoo River. While the emergency response phase has ended, clean-up of the contaminated landscape is ongoing.

On July 28, PHMSA issued a Corrective Action Order (CAO) to Enbridge requiring the operator to take specific steps to ensure the safety of the pipeline before the agency will allow the line to return to service. The CAO required Enbridge to submit a return to service plan providing procedures for repairs and monitoring the pipeline if it is allowed to resume service. The CAO also required Enbridge to submit an integrity verification plan including a comprehensive review of the operating history of Line 6B and prescribe further inspections, testing, and repairs within and beyond the immediate failure area. On September 17, PHMSA proposed an amendment to the CAO summarizing integrity information gained since the spill and setting out expectations for repair of known defects and the collection of additional integrity data. Enbridge agreed to the proposed CAO amendment and PHMSA issued a Final CAO on September 22.

On August 9, 2010, Enbridge requested permission from PHMSA to restart Line 6B. On August 10, 2010, PHMSA denied the request, finding that the restart plan did not adequately provide for the safe restart of the pipeline. In addition to requesting more details about the restart plan, PHMSA refused to approve any future restart plan that did not include at least four investigative excavations and a hydrostatic pressure test. Enbridge reviewed inspection data for the pipeline, excavated six locations, and conducted extensive tests of the exposed pipeline. At some excavation sites, repairs were warranted and in others no repairs were necessary. After completing the investigative excavations, Enbridge successfully pressure tested a portion of Line 6B that included the spill site on August 30, 2010. On September 3, 2010, PHMSA sent a letter to Enbridge requesting additional information about both integrity verifications and the proposed restart plan.

On September 21, Enbridge submitted a revised restart plan for Line 6B to PHMSA. Enbridge proposed to notify local emergency responders prior to restart, raise the pressure in increments with patrolling after each increment, and hire a third-party contractor to monitor the restart. On September 22, 2010, PHMSA approved the restart plan, allowing Enbridge to begin preparations for restart. After ensuring Enbridge complied with the preparation portion of the restart plan, PHMSA authorized Enbridge to resume the operation of Line 6B on September 26. The Line 6B restart plan was completed on September 28 and Enbridge may operate the pipeline subject to the pressure restrictions in the PHMSA CAO.

On September 26, 2010, Enbridge submitted an Integrity Verification Plan (IVP) to PHMSA. This plan incorporates all of the information learned since the spill. By integrating the results of metallurgical testing, assessment records, and repair history, Enbridge has developed a schedule for the additional integrity assessments and repairs required by the CAO. On November 1, PHMSA responded to the integrity verification plan with an expectation that Enbridge will include hydrostatic pressure testing and pipe replacement in the long term integrity plan. On March 18, 2011, PHMSA directed Enbridge to submit a revised IVP by April 15 and Enbridge has submitted a revision.