About 20 more officers and police department personnel will be needed in the next five years or so if a proposed $28 million police headquarters wins approval at the polls Tuesday, Lawrence Police Chief Tarik Khatib said Wednesday.

Khatib provided the estimate on Wednesday as voters have asked what else the department will need following Tuesday’s vote. If the plan does not win voter approval, more hiring might be needed, Khatib said.

“I would say the number is probably still close to 20 additional positions, or at least in the high teens,” Khatib said. “If this doesn’t pass, and if it doesn’t look like we are going to build a new facility anytime soon, then I think you are going to need some more numbers, especially in civilian staff, to try to make up for some of the inefficiencies.”

Throughout the discussions about building a police headquarters, Khatib has said he thinks more officers, in addition to the proposed new building, would be needed to improve service. At various times over the past several years Khatib has offered differing estimates on how much additional personnel would be needed. They include:

• In 2011, Khatib said in a memo to city administrators that the department had a fairly immediate need for about 30 additional employees, with the bulk of the new positions coming in the patrol and detective divisions.

• In 2012, Khatib told city commissioners that the department could use 46 additional positions over four years. The four-year plan had an estimated price tag of $12 million.

This week, Khatib said there are a couple of reasons for the differences in numbers. In 2012, he said, commissioners asked him to present his ideal staffing plan. He said the 46 employee plan represented that scenario, while the 30 employee plan was meant to address the most urgent needs.

Khatib said the number of anticipated hires has dropped to about 20 because the department has added nine officers since 2011, and has increased the property tax levy to bolster equipment purchases.

Some city officials said they think recent department improvements have been lost in the debate over the police facility and the proposed 0.2 percent sales tax to pay for the plan.

“I think it is important for the public to appreciate that public safety has been and will continue to be a priority for the city and the City Commission,” City Manager David Corliss said. “We have made funding our police department a priority.”

But there was about a decade where employee levels at the police department were stagnant. Khatib has noted on multiple occasions that in 2011 the department had 79 officers in the patrol division. That’s the same number the department had in 1999.

Khatib said he thinks that since 2011 there has been a new philosophy on how to staff the police department.

“Part of the challenge of that decade was that we didn’t seem to have buy-in above the department, and it was right in the middle of the Great Recession,” Khatib said. “I think the city was in survival mode.”

Opponents of the headquarters project, though, say city officials simply put other projects ahead of police department needs. Some opponents now say the city may be choosing to spend its money on the police department in the wrong way.

Jerry Harper, a former Douglas County district attorney and an opponent of the sales tax plan, said it is unclear whether facilities, personnel or a combination of both are what’s needed to improve the police department. He noted that Lawrence currently has more officers per 1,000 residents than many of the cities in a national police benchmarking survey. But that same survey shows Lawrence has lower clearance rates than many of the communities.

“A big question is whether adding officers is the solution,” Harper said. “I don’t know. I still think we need to have a blue-ribbon commission of outside experts study the department from top to bottom. You have to study everything from top to bottom before you jump in and spend $28 million.”

Corliss said he sees the need for additional officers and will continue to advocate for additional positions in future budgets.

How the city will fund the new officers, however, isn’t clear. The 0.2 percent sales tax does not include money for hiring. The funds from that sales tax will be used only for building and equipping the building.

In the past few years, officers have been added to the force after the department submitted annual requests for funding from the city’s budget. City commissioners have used property tax increases to fund the additional positions. They approved a 0.33 mill increase in 2013 to add three officers and a 0.15 mill increase for the 2015 budget to add a sergeant. Khatib said the year-by-year approach is likely the strategy that will be used in the future.

“I think what people are having a hard time understanding is that in politics and city government, you get things done over time,” Khatib said. “You try to bite off chunks you can handle, and then move on to the next chunk.”

The amount of money needed to fund 20 new positions depends on the type of positions. Based on past city figures, a patrol officer adds about $70,000 to the city’s budget, when benefits and other costs are added. A detective adds about $80,000 and a sergeant adds about $120,000.