The Colorado Energy and Carbon Management Commission notified Chevron subsidiary Noble Energy on Thursday that it is under investigation for six alleged violations related to the massive blowout of a fracking well in Weld County this spring.

The violations pertain to well control, general safety requirements, oil and gas facilities operations, air, water and soil pollution, and natural gas venting, according to a presentation to the commission about the April blowout, which covered a school and homes near Galeton with pollutants and will take five years to clean up.

The ECMC served Noble Energy with a notice of the alleged violations, the first step in launching a formal investigation into missteps that caused thousands of barrels of crude oil, natural gas and fracking water to spew from the Bishop well pad. The company has 28 days to respond to the allegations.

Jeff Deranleau, the ECMC’s deputy director of operations, said the commission’s investigation could lead to fines and other enforcement actions for the company. The investigation could take months, and the penalties will be negotiated between the state and Chevron. The seven-member ECMC board must give final approval of any penalties.

The decision to pursue an investigation into rule violations follows Chevron’s submission of a root-cause analysis on June 10 that pinned blame on a subcontractor and also on its employees for improperly installing equipment at the wellhead to regulate the flow of oil, gas and water from the ground.

The company’s two-part explanation said the blowout happened during a period after fracking had been finished and before extraction began.

But the ECMC’s notice of alleged violations did not name the subcontractor nor any other individuals working for Noble Energy or Chevron.

“I want to note that, importantly, regardless of who or what causes an accident, spill, leak or other incident on an oil and gas location, the ECMC holds the operator of record accountable for the operations conducted on their location as the control of the location is solely in their hands,” Deranleau said.

Noble Energy, which is a wholly owned subsidiary of Chevron, holds the drilling permit.

Patty Errico, a Chevron spokeswoman based in Colorado, said in an email that the company was reviewing the violation notice. The cleanup and remediation continue, and the company will cooperate with federal and state agencies, she said.

“We understand that rebuilding trust takes time and sustained effort. We remain committed to open, ongoing dialogue and to supporting the residents of Galeton as we move forward — together,” Errico’s statement said.

The state’s notice alleges that Chevron failed to prevent oil, gas and water from flowing uncontrolled from the well and failed to follow general safety requirements, leading to at least one worker’s injury when the blowout happened, according to the document.

As for the pollution violations, the blowout spread contaminants to a school, homes, farmland, surface waters, wildlife habitat and livestock, the notice of alleged violations stated. The company failed to prevent the pollution and its adverse impacts.

The blowout also violated the water quality standards established for oil and gas operations after Chevron built an unlined pit to retain runoff from the blowout.

Finally, the notice alleges that Chevron vented natural gas from the well, which is a violation of state rules.

The blowout was one of the largest spills in Colorado in recent memory, Deranleau told the commission.

“Well-control incidents are rare,” Deranleau said. “The specific cause of this incident, as reported by Chevron, is related directly to proprietary equipment and improper assembly of the equipment, meaning it’s not even the same root cause of other well control incidents that have happened in the past in Colorado or elsewhere.”

After the blowout, the ECMC sent a notice to 42 other oil and gas operators in Colorado, advising them of the incident and asking each company to report to the state how it handles equipment installation between fracking and extraction.

Their responses and the ongoing investigation into the Bishop well blowout could lead to policy changes, said Mike Leonard, the ECMC’s quality assurance/quality control manager.

The massive blowout occurred at 5:50 p.m. April 6 at the Bishop well south of Weld County Road 74, near Galeton, about 14 miles east of Greeley.

It lasted five days, leading to the closure of Galeton Elementary School and the evacuation of 14 families. One worker suffered a broken leg when a piece of equipment fell on him during the incident, Deranleau said.

The blowout spewed 20,000 barrels of water and 5,000 barrels of hydrocarbons into the air, and those liquids covered the school, homes and other structures within a 1.5-mile radius of the well — an area that covers seven square miles, or 4,500 acres.

Toxic chemicals, including benzene, hung in the air, flowed into ponds and streams and seeped into the groundwater.

The state has divided that area into 300 parcels that each have a specific remediation plan, and the ECMC expects the cleanup to last through 2030.

So far, the ECMC has received 730 surface water samples, 2,203 soil samples and 475 air samples, said Kyle Waggoner, the commission’s east environmental supervisor. The agency is also conducting tests on the surfaces of the school, homes and other structures that have been cleaned to make sure all hazardous pollutants have been removed.

“How do we make this a successful remediation site? In other words, how do you eat an elephant?” Waggoner said.