Franklin County commissioners got a look Wednesday at three different plans for the aging Juvenile Justice Center.

Each of the plans would expand the facility — shared with Benton County — to more than 37,000 square feet, up from the existing 15,164 square feet. But they differ in how much of the existing 1979 building would be kept.

The existing building is considered cramped. The situation is only expected to worsen as the combined populations of Benton and Franklin counties grow by an expected 51 percent over the next 25 years, according to a report from Dyron Murphy Architects of Albuquerque, N.M.

“There are two and three people in a space designed for one person,” said Richard Frederkind, the Seattle-based project manager for Dyron Murphy.

The first plan, estimated at $7.18 million, calls for keeping most of the existing building at the corner of Canal Drive and Grant Street in Kennewick, but adding a three-story building.

The second plan, projected to cost $7.71 million, would save 5,000 square feet of the existing building, demolishing the rest. Another three-story building would be connected to the existing building on the property, which is shared with a Benton County Annex and Fire District 1 station.

The third option would completely demolish the old building and replace it with a new 37,000-square-foot, two-story facility. The all-new building would also be the most expensive at $8.33 million.

“The option that gives you the longest life for the project is obviously option 3,” Frederkind said. “It’s more expensive, but it’s going to give you 50 years.”

The second and third options would require juvenile court and other services to be moved to temporary quarters during construction, which could require the counties to lease property temporarily.

“In broad, general terms I favor new over retrofit, and eating the cost of displacement,” commission Chairman Brad Peck said.

The architects presented the plans to Benton County commissioners sTuesday.

They plan to return to commissioners with a final presentation on the three options in June, said Darryl Banks, Juvenile Justice Center administrator.

Peck noted that no one had talked about how to pay for the new building.

“Right,” Banks said.

The county commissions might be able to meet jointly again shortly after the next presentation. A bill sponsored by Rep. Larry Haler, R-Richland, which would allow for two or more county commissions to meet together, passed the Senate 49-0 Monday and now needs Gov. Jay Inslee’s signature.

“It will be signed by the governor,” Haler said Wednesday afternoon.

The law would likely go into effect July 1, he said.

Peck would have preferred an amendment be added to House Bill 1145 dealing with the number of commissions that could meet, and requiring them to meet in an impacted county, he said.

“If five counties in Eastern Washington want to have a meeting in Bellingham for any reason, this will allow that to occur,” he said.

Not every bill is perfect, Haler said.

“Those are the kind of amendments we can make to the law next year,” he said.

Benton and Franklin commissioners had regularly held joint meetings, where bi-county departments like the Juvenile Justice Center, human services and Superior Court were discussed. But they learned last year that such meetings were not allowed under state law except in rare circumstances.