It is a fact of life: Lawrence city commissioners don’t know everything. But on most occasions they can spend money on a team of consultants who do.

At their meeting tonight, commissioners are expected to solicit consultant proposals to study the feasibility of a downtown library expansion.

Mayor Mike Rundle is fine with commissioners seeking expertise on such issues. But city leaders should take a hard look at how often they call consultants, he said.

“I think we have the base of expertise on our city staff to do a lot of these things in-house,” Rundle said.

Rundle said he was not particularly concerned about the city using consultants for specialized projects. For example, in 2004-2005 the city spent $52,000 to study utility rates, $12,000 to begin studying the fiscal impacts of growth and $57,980 to study the resources of the Lawrence Police Department.

However, the mayor is concerned about the number of engineering firms the city hires to design road, sewer, water line and other similar projects.

“I just can’t believe that for the amount of money we spend, we couldn’t hire a couple of additional people to do this engineering work,” Rundle said.

Rundle said he reviewed City Commission agendas from 2004 and found the city spent $2.87 million in engineering fees. He said that was a sign the city’s planning, neighborhood resources and public works departments were understaffed.

“I think we have a number of departments that are not staffed well enough for a city our size that is growing at the rate we are,” Rundle said.

City Manager Mike Wildgen said the issue was worth studying. But he said more in-house engineering work would require the hiring of not only engineers but also support staff.

“And there is an argument that during lean times, what do you do to keep all those people busy?” Wildgen said.

Wildgen said there also were other advantages to having consultants tackle some projects. For example, Wildgen said, the consultants the city hired to study water and wastewater rates were able to share how other cities structure their rates.

“Sometimes they give us knowledge that we wouldn’t otherwise have,” Wildgen said.

The city does not have a specific line item in its budget that tracks fees spent on consulting services, which makes it difficult to determine if the use of consultants has increased significantly.

Wildgen said the use of consultants generally rose and fell depending on the interests of the commission.

City commissioners have set aside up to $200,000 to hire a prime consultant for the library project. The consultant would be responsible for assessing the current library at 707 Vt., reviewing the feasibility of three potential downtown sites, leading a community workshop to explore various opportunities for the library and exploring possible funding options for a new library.

Commissioners hope to select a consultant by the end of April. The consultant’s report is due by July 15.

Commissioners will discuss the request for proposals at their meeting at 6:35 p.m. tonight at City Hall, Sixth and Massachusetts streets.