WINDSOR — PDC Energy workers at the site of an 84,000-gallon spill of greenish, oil-laden fracking fluid on Thursday said they had pretty much cleaned up the mess.

No access was allowed. Trucks hauled away a yellow dirt-moving machine and other equipment. There were no state inspectors at the site.

“The location is, I believe, cleaned up,” PDC vice president Bart Brookman said by phone, en route to Grand Junction. Denver-based PDC operates about 2,500 wells in the Watterberg formation along the Front Range.

Colorado Oil and Gas Conservation Commission regulators “are continuing to monitor the cleanup,” state spokesman Todd Hartman said. “Rest assured we will be physically engaged — present — at the site.”

The spill this week ranked 55th in volume out of 5,177 spills recorded in a COGCC database.

The state records show that PDC has reported a dozen spills over the past year, including six in 2013. None released as much fluid as the spill that started after a mechanical failure Monday morning. Water fouled with oil and chemicals used in hydraulic fracturing sprayed from the well about 4 miles north of Windsor for more than 30 hours.

A Jan. 22 spill released 2,880 gallons of oil, contaminating groundwater with benzene, toluene and xylene chemicals.

PDC was last fined in 2008, for improper practices in Yuma County. The company paid $6,000.

Oil and gas companies expanding operations around Colorado have reported more than 2,000 spills over the past five years, with roughly 17 percent contaminating groundwater. Fracking wastewater frequently is listed among substances spilled into soil and water.

Some spills that PDC reported were identified as “historic” — presumably caused by previous well operators.

“PDC in some or many cases is discovering historic issues, reporting them, and remediating them, as is required by our regulations,” Hartman said. “We consider that the action of a good operator, not a bad one.”

The liquid spilled near Windsor did not appear to reach surface streams or ponds. No determination had been made on whether the chemicals contaminated groundwater.

The well is just outside Windsor’s town limits but is inside its “growth management area,” where 452 wells are located. There are 232 wells within town limits.

Town Manager Kelly Arnold said no other spills have been reported near Windsor.

“We’ve got a good relationship with the industry. We’ve worked with them hard,” Arnold said. “We don’t know this company.”

Town leaders and residents, he said, “believe that companies need to be doing their business correctly.”

Windsor recently applied for an $800,000 grant from severance-tax revenues — collected from energy companies by the state — to finance a new municipal water-storage tank needed for public safety and to help residents endure drought.

Bruce Finley: 303-954-1700, twitter.com/finleybruce or bfinley@denverpost.com