On the morning of Dec. 8, 2022, TC Energy reported a pressure drop in a 36-inch crude oil pipeline, part of the Keystone pipeline system near Washington, Kansas. The pressure drop was documented at approximately 9:30 pm on December 7, 2022. The pressure drop was confirmed to be from a line rupture south of a Mill Creek crossing. The pipeline rupture resulted in wide-spread vegetation staining. In addition, oil discharged overland and into Mill Creek, a nearby perennial stream. TC Energy estimates the total oil volume discharged as 588,000 gallons (14,000 barrels).
Two EPA On-Scene Coordinators (OSC) mobilized to the response the morning of Dec. 8, 2022, integrating into Unified Command with Kansas Department of Health and Environment (KDHE) and TC Energy. TC Energy enacted their pipeline response plan and commenced oil containment and recovery activities mobilizing numerous resources including oil containment booms, vacuum trucks, frac tanks, light stands for night operations, and heavy equipment. Impacts to Mill Creek initially extended approximately three miles downstream to a bridge crossing at 20th Street. To provide containment and prevent downstream migration of oil on Mill Creek, an underflow dam was constructed on the creek at a low water crossing road approximately four miles downstream of the pipeline rupture.
Operations were performed 24/7 during the initial bulk oil recovery phase. This phase was completed on Jan. 29, 2023 when the recovery of bank-to-bank oil on Mill Creek was complete. Following substantial construction and engineering projects, response personnel were able to access submerged oil impacts in Mill Creek when the creek was dewatered to recover oil-impacted debris, sediment, and vegetated shoreline. Oil recovery within Mill Creek continued until May 11, 2023, when response crews shifted their focus to stream restoration.
In May, under the U.S. Army Corps of Engineer’s (USACE’s) Nationwide Permit 27: Aquatic Habitat Restoration, Enhancement, and Establishment Activities, restoration to Mill Creek began. Through this permit, the restoration work occurred to allow for Mill Creek to be restored to its original condition, form, and functions. Additional response-related tasks, such as the disposal of oil-impacted soil and sediment and response-generated waste, and the restoration of lands impacted by the response, remained ongoing during this timeframe.
EPA Region 7 confirmed that the removal of oil was complete during a final visual inspection of the creek completed on Friday, Oct. 13, 2023. Mill Creek is once again flowing naturally. EPA staff worked more than 6,000 hours and took over 83 trips to the scene. EPA personnel from Regions 3, 5, and 6 supported Region 7, along with staff from the U.S. Coast Guard – Atlantic Strike Team. In total, more than 54 million gallons of contaminated surface water were treated and discharged back into Mill Creek. Over 650,000 gallons of oil were recovered, including product remaining in the pipeline following the rupture. Approximately 200,000 tons of oil-impacted soil, sediment, and debris were excavated and sent off-site for disposal.