A new way of hiring contractors to build ferry terminals could, according to at least one state senator, reduce the cost of building such structures.

The bill, approved by the state Senate and currently being considered by the House of Representatives, is too late for the Clinton ferry dock reconstruction project — which is expected to be finished this summer — but, according to its sponsor, Sen. Mary Margaret Haugen, D-Camano Island, the bill could keep down the cost of a proposed terminal relocation and expansion of the Mukilteo dock.

The bill authorizes Washington State Ferries to choose a single contractor to design and build ferry terminal projects. It also allows WSF to partner with one firm that would assist in a project’s design phase and act as the project’s construction manager and general contractor.

Using a “design-build” contractor creates a single point of accountability on a project, Haugen said. It makes for a more reliable construction timeline, reduces the likelihood of expensive cost overruns and eliminates the adversarial situation that often develops when multiple contractors work on a single project.

It is a process already in use by a number of state agencies including the University of Washington, Washington State Department of Corrections and by port districts.

Speaking from Olympia this week, Haugen said savings for some school projects by using the same system have been as high as 30 percent of a total bid.

The bill would be the first law that would take this single-contractor study statewide.

“Until now it has been really limited to cities with populations of at least 450,000,” Haugen said.

The state already uses alternative contracting procedures to build highways and ferry boats. Haugen’s bill extends the practices to ferry terminals.

Haugen’s bill, known “agency request legislation” was sought by Washington State Ferries.

“It’s a logical method to for upgrading terminals,” said Russ East, director of terminal engineering for WSF. “If passed, the bill will give us more tools to solve complex jobs.”

The bill would only apply to construction jobs with a price tag greater than $12 million.

The cost two-phase project at the Clinton dock and terminal was $27 million. Two contractors did the work, each building a half of the project.

East said the savings for using one contractor would have been in the tens of thousands of dollars.

“But I would expect the saving to be about 2 percent, or $54,000,” he said.

On larger, more complex job, savings could be greater, he said. The other advantage to having a single contractor would be in project completion time. East said keeping the same contractor site to finish one job would eliminate some delays.

Long-delayed upgrades to the ferry terminals at Seattle, Anacortes and Mukilteo would be prime candidates for alternative contracting because they are large and complex, Haugen said.

Alternative contacting practices have been used successfully by other state and local agencies such as the University of Washington, the state Department of General Administration, the cities of Seattle and Bellevue, and the ports of Seattle and Portland.

Haugen said she is confident that her bill will pass in the House.

Haugen is the ranking Democrat on the Senate Transportation Committee.