This March 23, 2011 photo shows the El Dorado Correctional Facility near El Dorado, Kan.

TOPEKA ? A union representing Kansas state employees said Friday that some officers are being required to work 16-hour shifts at a maximum-security prison that was the scene of an hours-long inmate disturbance last month.

The Kansas Organization of State Employees disclosed that it filed a grievance earlier this month directly with Corrections Secretary Joe Norwood. The union said requiring El Dorado Correctional Facility officers to work such long shifts violates a bargaining agreement between employees and the department.

Robert Choromanski, the union’s executive director, said the practice also is dangerous. He said eight officers complained to KOSE, which filed its grievance with Norwood on July 12. He said the extra-long shifts began in early July — only days after the disturbance.

“It’s hard for a human being to work more than 12 hours a day,” Choromanski said. “It is a safety issue.”

The state prison system has been plagued with high turnover rates in recent years because the pay for corrections officers is often lower than that in the federal prison system or at many county jails.

The department informed the union in mid-June that it would require employees to work 12-hours shifts at least until mid-September, a practice allowed by the bargaining agreement. But Choromanski said the El Dorado officers complained because an additional four hours sometimes are being added to those lengthened shifts.

“They have no time for their families,” he said.

Department of Corrections spokesman Todd Fertig declined to comment “on what is a personnel matter.”

The El Dorado prison houses some of Kansas’ most dangerous offenders, despite having a mix of medium- and maximum-security cells. The prison opened in 1991 about 30 miles east of Wichita. The prison held about 1,800 inmates as of Thursday, about 100 fewer than it did on June 29, when the disturbance occurred. Its population increased between March and June.

Choromanski has said the disturbance began when some prisoners refused to return to their cell houses. He said inmates for a time controlled parts of the prison, including the gym, the yard and the kitchen.

The department reported no major injuries from the disturbance but refused to release reports on the incident or prison video from that day in response to an open records request from The Associated Press.

In filing the grievance, KOSE cited a section of the agreement between employees and the Department of Corrections that says no employee shall be required to work more than 12 hours in a single 24-hour period. Another section says with “an officially declared emergency,” an employee can be required to work 18 consecutive hours, as long as six hours of rest follows.

Choromanski said the corrections secretary has until Aug. 2 to respond to the grievance. The union can seek arbitration, but an arbiter’s decision is appealed to Republican Gov. Sam Brownback, who appointed Norwood. A lawsuit is possible after that.