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Mill Creek restoration an example of interagency collaboration and innovation

Staff from the Regulatory Office, Kansas City District, U.S. Army Corps of Engineers, staff from TC Energy Corporation and environmental design and restoration crew members work together during the restoration phase of the Mill Creek oil spill response on August 23, 2023.

Posted on November 21, 2023

At approximately 9:30 p.m. on the evening of December 7, 2022, a pressure drop in the Keystone Pipeline system was reported by TC Energy Corporation. Not long after the reported pressure drop, a rupture was detected, and 588,000 gallons of oil spilled into Mill Creek. Located just a few miles northeast of the city of Washington, Kansas, the oil spill in Mill Creek was the largest in the history of the Keystone Pipeline and the largest onshore oil spill since 2014.

This is a story that highlights the quick action of local emergency management, the vital cooperation between federal, state, local and Tribal partners, and the use of innovative bioengineering techniques resulting in a comprehensive restoration project. This is a story that also demonstrates how partners working toward a shared goal can accomplish the seemingly impossible.

Response efforts

When an oil spill is detected, the U.S. Environmental Protection Agency is notified, and their emergency response personnel are dispatched to assess the situation. On December 8, 2022, EPA on-scene coordinators from EPA Region 7 were called to Mill Creek to begin overseeing and directing the federal government’s response to the oil spill. The first step was removing oil from the impacted area.

“The response was conducted using what we call Unified Command, which involved the EPA, the Kansas Department of Health and Environment and TC Energy [Corporation],” said Jeff Pritchard, who served as the lead on-scene coordinator for EPA’s response. “All of the oil removal activities were conducted under EPA’s authority.”

Although EPA leads the federal response after an oil spill, it is done so in part under Nationwide Permit number 20, which is issued by the U.S. Army Corps of Engineers. By bringing USACE into the operation from the very earliest stages of response, EPA was able to initiate immediate removal activities.

“Nationwide Permit number 20, which is a USACE-issued permit, covers activities in response to oil spills,” said Matt Mikulecky, regulatory project manager at the Kanopolis Regulatory Office, Kansas City District, USACE. “[Through early coordination with USACE, EPA was] able to immediately direct the necessary work within the stream to contain the oil spill.”

The work necessary to contain the oil spill was no small feat. Requiring as many as 700 to 800 people, at times working around the clock, removal efforts were completed using a two-phased approach. According to Pritchard, the 588,000 gallons of oil impacted about 3 ½ miles of the creek before it was contained.

“Phase one was removing the oil off the surface of the water,” said Pritchard. “Phase two was once we got [the surface] oil removed, we still had all the oil impacted in the creek bank and vegetation.”

The challenges the team faced in removing the oil were several: December temperatures in Washington, Kansas, were frigid, making oil removal in the creek difficult. Furthermore, the type of oil that was spilled was a heavy, enriched oil, which can sink in water whereas most oils float in water. This heavy oil impacted not only the creek bed, but also deeper banks, which required excavation of the impacted creek sediments.

As is often the case, challenging circumstances provide the opportunity to problem solve, sometimes in new and innovative ways. Due to the heavy oil that spilled into the creek, removal crews ended up damming and diverting the creek, which allowed for excavation of the creek bed and banks. According to Pritchard, this is not typical in oil spill response efforts.

“There were several different engineering features that were implemented here that are not normal for oil spill response,” said Pritchard. “[Diverting] the creek … you don’t normally see that.”

The second phase of the response, which addressed oil impacts to sediments and shorelines, was completed on May 13, 2023. While the hundreds of individuals who worked diligently to remove the oil were instrumental in the response efforts, both Pritchard and Mikulecky credit the overall success to the actions of local emergency management.

“Because of the quick response by the local emergency management folks, they were able to construct a dam four miles downstream of the spill and were able to limit the majority of the contamination,” said Mikulecky.

According to Pritchard, the local emergency management response was critical to initial response efforts.

“Their actions were key to actually stopping and containing the oil spill in Mill Creek,” said Pritchard. “The local emergency management office was very vital to the response when it was discovered that night [December 7, 2022].”

Restoration efforts

Once the oil recovery and removal activities were completed within Mill Creek, EPA transitioned the federal government’s response to USACE for restoration of the stream.

“The mission of [USACE’s] regulatory program is to preserve and protect the integrity of our nation’s waters,” said Mikulecky.

In the case of the Mill Creek Oil Spill, Mikulecky and the rest of the Kanopolis Regulatory Office of the Kansas City District reviewed TC Energy Corporation’s restoration plan. This included sharing information among the many federal, state, local and Tribal partners involved in the project.

“Our role with the restoration phase was to … provide input and guidance on restoration activities that [TC Energy Corporation] proposed, and we were able to do that with interagency and Tribal collaboration,” said Mikulecky. “Once we completed that collaboration, we went ahead and authorized the restoration plan.”

As previously noted, the type of oil that spilled required the creek to be dammed, diverted, and excavated to remove it. Restoration activities included reconstructing the creek to its original condition.

“When you are excavating from a stream, you are changing the channel characteristics quite a bit,” said Mikulecky. “The geomorphology of the stream was severely affected by recovery efforts. Our goal was to ensure that the restoration would at least restore the stream to its pre-incident condition.”

As of October 2023, the construction phase of the restoration project has been completed. USACE will continue to monitor the structures in the creek through periodic inspections to ensure that the instream work continues to perform as it was designed. The Kansas Department of Health and Environment will monitor the water quality of Mill Creek.

As the one-year anniversary of the oil spill nears, it is hard for some of those involved from the beginning to believe the transformation Mill Creek has gone through.

“My first day on the site, I couldn’t visualize the site ever recovering and then to see it today is really remarkable,” said Mikulecky. “It’s been highly successful and that’s due to the numerous state and federal agencies involved from the very beginning, and who provided valuable input and review of the response and restoration projects.”

Mill Creek after the completion of restoration activities led by the Kansas City District, U.S. Army Corps of Engineers.

Oil in Mill Creek after the Keystone Pipeline oil spill that occurred on December 7, 2022, near Washington, Kansas. The Environmental Protection Agency was responsible for the response and recovery activities at Mill Creek. The U.S. Army Corps of Engineers was responsible for the restoration of Mill Creek.


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