Miami-Dade County has agreed to a long and expensive list of ways to improve how it treats its inmates — particularly those who are mentally ill or suicidal, bringing to an end an investigation the U.S. Department of Justice launched five years ago that found civil-rights violations at county jails.

As part of two agreements approved by county commissioners Tuesday, Miami-Dade must construct a mental-health treatment facility for inmates, which is estimated to cost between $12 million and $16 million to build and more than $29 million a year to operate.

The county must also install a $6 million electronic jail management system that will cost an additional $500,000 a year to maintain, install an additional $1.2 million in video monitoring equipment and spend $1.3 million more a year to train corrections employees.

“It’s time that we change the way we’ve been dealing with this problem,” said County Judge Steve Leifman, a longtime critic of the jail system and reformer who for years has pushed for the mental-health facility. “This is an excellent step in the right direction.”

The DOJ wrapped up its three-year review in 2011, concluding that Miami-Dade’s jail system — the eighth-largest in the nation — engaged in a “pattern and practice of constitutional violation” against inmates housed in deplorable living conditions under abusive, inadequate or limited care.

Since then, officials in the county’s Department of Corrections and Rehabilitation and in the Jackson Health System, which provides medical care for inmates, have been negotiating with the feds, noting improvements they have already made and hashing out the final accords.

The county and the Public Health Trust that oversees Jackson signed a “consent agreement,” which will be enforced by a federal judge, over the medical and mental health-care issues. The county signed a separate “private party settlement agreement,” not under court oversight, over jail operations issues, some of which Miami-Dade has already addressed.

Among the required changes, the jails must:

• Have a medical doctor or psychiatrist evaluate inmates with serious medical or mental conditions within 24 hours of their arrival.

• Report to the court and DOJ each death or serious suicide attempt within 45 days of each incident.

• Require suicide-prevention training for officers.

• Prohibit retaliation against inmates by sending them to suicide-watch cells.

Require visual observation every 15 minutes of inmates who are restrained.

• Provide group counseling sessions for mentally ill patients, as needed.

• Create an “Early Warning System” to document and track corrections officers involved in excessive use-of-force incidents.

• Report use-of-force incidents to supervisors no later than 24 hours after they occur.

Prohibit threatening inmates with the use of restraints.

• Require fire drills every three months on each shift.

Miami-Dade’s jail system has long been plagued with problems. Inmates sued for overcrowding in the 1970s — a condition a federal judge declared unconstitutional 1984. The case was settled after 25 years. Grand juries issued blistering reports on jail conditions in 2004 and 2008.

Last month, state health inspectors investigated conditions at one jail after an employee complained about rats. Inspectors did not find rodents but did identify cracks and holes in walls and pipes that would let rats come into the jail’s kitchen.