A Denver contractor cut checks for nearly $250,000 to dozens of its employees after city officials discovered a payroll error during a routine city audit.

Nelson Pipeline Constructors, a subcontractor on Beeler Park construction in Denver’s Stapleton neighborhood, failed to pay 91 employees wages totaling $241,000 due to a classification error, City Auditor Timothy O’Brien said.

“The employees owed back pay were done a disservice by not receiving their full wages on time,” said O’Brien. “But with strict accountability measures in place, we can find these errors and make it right as quickly as possible.”

Anytime the city does business, involving capital improvements, maintenance, janitorial work or other work, contractors are required to pay workers a prevailing wage, which is set by the federal Department of Labor.

Denver’s prevailing wage ordinances were passed in the 1950s and is required on all contracts of more than $2,000, with the idea that workers be paid a living wage. All companies contracting with Denver provide the city with electronic payroll information, O’Brien said. It is the only local entity that sets a prevailing wage, according to Denver Director of Communications Kathleen Mackenzie. More than $800,000 in underpayments for workers on Denver projects were recovered in 2016.

The classification error was discovered on a routine visit to the construction site by a prevailing wage investigator, O’Brien said.

“They weren’t aware of the law, it wasn’t a conscious effort on their part,” O’Brien said of the back pay error.

“Nelson Pipeline did everything it could to rectify the underpayment,” O’Brien said. “This is the kind of relationship we want with employers who contract with the city.”

A spokesperson at Nelson Pipeline couldn’t be reached for comment.

Last year, Denver started a new dispute process by which contractors could appeal prevailing wage decisions made by the auditors office. O’Brien said no one has used the appeal process yet.