A deal is all but done between the city and its police and fire unions, as City Hall leaders announced a tentative four-year agreement that will provide raises to public safety employees through 2015.

But the explaining to non-union City Hall employees may be just beginning as the deal announced Tuesday widens differences in pay strategies between public safety employees and other city employees who staff everything from the water department to street crews.

“We are doing more on the union side this year,” Mayor Aron Cromwell said. “Everybody’s job is super critical, but it is somewhat different to be getting a call and really have someone’s life on the line. We have to acknowledge that there is a difference.”

Cromwell said it was a “priority” of the commission to bring the wages of police and firefighters up to the average paid by surrounding communities.

The tentative agreement, which still must be ratified by the police and fire unions and approved by city commissioners at their Aug. 16 meeting, calls for:

• General wage adjustments of 1 percent in 2012, 1.5 percent in 2013, 1.5 percent in 2014, and 1 percent in 2015. All members of the union will receive those annual increases, except for police detectives. Detectives already were found to have wages well within the average of area communities. Detectives won’t be eligible for a general wage increase until 2015.

• Police officers and firefighters who are not already at the top of their pay scale will be eligible for either a 2.5 percent or 5 percent merit wage increase. Unlike the general wage adjustment, which is similar to a cost-of-living adjustment, the merit wage increase is based on an employee’s performance review. Not all police and firefighters will be eligible for a merit increase. About 75 percent of firefighters are ineligible because they are at the top of their pay scale, and about 65 percent of police officers are at the top of the scale.

• Police officers also are eligible for another 2.5 percent wage increase that is based on an officer adding certain competencies, such as foreign language skills or other special training. Firefighters are eligible for anywhere from a 2 percent to 7.5 percent wage increase if they add certain competencies such as arson investigation training, coroner training and other specialties.

Non-union employees, which include all city employees except police and fire, are facing a different scenario when it comes to raises in 2012, with most employees receiving a little more than a 1 percent increase in wages.

The city, since 2008, no longer provides general wage adjustments for non-union employees. Instead, all non-union pay increases are based on employee evaluations. In 2012, the city has budgeted for merit increases that average 1.2 percent. Like police and fire employees, city workers aren’t eligible for merit pay increases if they are at the top of their pay scale. An estimate on how many non-union employees are at the top of the scale wasn’t immediately available.

City Hall leaders said they do hear some concerns from city employees about how the two pay plans have become significantly different.

“From time to time, we do get comments about that,” said Diane Stoddard, assistant city manager and the city’s lead negotiator in the employee talks. “That is an issue we just need to continue to monitor and one that the City Commission will need to monitor as well.”

Detective Mike McAtee, chairman of the Lawrence Police Officers Association, said, though, that preserving the current pay system was a high priority for the 122 members of the police union. McAtee said the system helps with recruiting and reduces turnover, which saves the city money in training new hires.

“Our current system of pay dates back over 30 years,” McAtee said. “It promotes a logical career path, which we think is extremely important.”

McAtee said the union’s executive board would strongly encourage its members to ratify the agreement before the Aug. 16 commission meeting.

“We’re very happy with this,” McAtee said. “We think it speaks to the city’s commitment to recruit and retain quality city employees.”

The leadership of the International Association of Firefighters Local 1596 also has expressed support for the agreement, but an attempt to reach the association’s president for comment was not successful Tuesday. Technically, neither the LPOA or IAFF are unions because their members do not have a legal right to strike, but they do have many of the same bargaining rights as unions.

The proposed agreement also will treat union and non-union employees differently when it comes to overtime. The city earlier adopted a new overtime policy that no longer allows paid time off — other than holidays — to be counted toward the 40-hour calculation used to determine when an employee must be paid overtime. But that new policy change didn’t apply to the unions.

City negotiators tried to get the new policy included in the new union agreements, but were unsuccessful. The union employees will continue to operate under the old policy.

Cromwell said he’s disappointed the unions would not accept the change, but is willing to move on in the interest of getting a long-term deal, which marks the first multiyear agreement between the unions and the city in several years.

“All along, getting a four-year deal was a big priority of mine and really the whole commission’s,” Cromwell said. “There is a ton of time spent in these negotiations, and negotiations like these can breed ill-will. This was a real important issue for us to get past.”