EVERETT — The old Carnegie library is about to go back into circulation.

In this incarnation, the historic downtown building on Oakes Avenue could see new life starting this fall as a one-stop-shop for social services. The idea would be to keep people off the streets and, if possible, out of the Snohomish County Jail next door. It’s tentatively set to open in September.

“We were really looking at a facility where people could be taken as opposed to going into booking in jail, as a way of providing for other services, as well as for people exiting jail who needed help with transitioning back into the community,” county human services director Mary Jane Brell Vujovic told the County Council earlier this week.

People could go there to connect with mental health, housing or job-training services. The target population includes people who might otherwise use emergency rooms, 911 or other public services.

If things go as planned, the Carnegie’s upstairs would complement the new diversion center next door that opened earlier this month.

Unlike the Carnegie programs, the diversion center is for overnight stays. People can remain there for up to 15 days, until they connect with longer-term treatment programs for drug addiction, mental illness or supportive housing. There are 44 beds.

A few years ago, county officials envisioned the diversion center in the lower floor of the Carnegie building. They opted instead to put it in an empty space next door, which had housed the jail’s now-discontinued work-release program. That also provided twice as much room for the diversion program.

While the Carnegie’s upper floor is slated for social services, plans for the lower floor are in progress, officials said. It could be used as meeting space. One idea is to start an alternative court for low-level crimes involving people who are homeless, substance abusers or suffering from mental illness.

“Six months from now, we may come back with a completely different idea based on our own local experience, based on our experience with our municipal partners,” Sheriff Ty Trenary told the council.

Costs for remodeling the Carnegie building interior are now estimated at just over $2.5 million. That’s more than double the estimate from when the service center was conceived during the administration of former County Executive John Lovick, who left office after 2015. The County Council never vetted the earlier concept. Adding to the expense are needed upgrades to the building’s mechanical and electrical systems, as well as big run-ups in labor costs in the booming construction market.

Nearly $1 million has been spent to date.

The county has contracted with Seattle-based Pioneer Human Services to run the Carnegie programs. The contract is expected to cost about $250,000 during its first full year, said Mike Fulcher with the county human services department. Pioneer also is under contract to run the diversion center.

Money has come from the county’s chemical dependency-mental health sales tax and state funds.

The costs are in addition to seismic upgrades and exterior restoration efforts on the 8,800-square-foot building. The Legislature in 2015 provided the county with more than $1.3 million for Carnegie renovations.

The 1905 Carnegie building originally housed the city’s library, which moved out in 1934. The building went on to become a funeral parlor and later was used for the county’s information technology workers. At one point, it was considered as a potential site for a museum or a law library. It’s on the National Register of Historic Places.

Noah Haglund: 425-339-3465; nhaglund@herald net.com. Twitter: @NWhaglund.