OLYMPIA - The Olympia City Council is set to vote tonight on a cleanup plan for the East Bay site of a new $18.5 million Hands On Children's Museum.

The cleanup must be completed before groundbreaking, which is planned for September.

The cleanup plan is part of a larger environmental agreement – called an agreed order – involving the state Department of Ecology, the Port of Olympia, the City of Olympia and the LOTT Alliance. All the parties are part of the redevelopment of the site.

“We’re still completely on track for groundbreaking for September this year,” said Patty Belmonte, executive director of the museum. “We are just delighted that this action is happening because it is a necessary and important step in the process toward a new children’s museum.”

If the council acts tonight, it sets in motion a state approval process. Thirty days of public comment will be taken, after which the state will decide whether to accept the cleanup plan, said Jay Burney, assistant city manager for special projects. The project also has to be put out for bids.

The city hopes to begin construction on the 1.8-acre site in September, Burney said.

“The city is very pleased … with where things are on this project,” he said.

East Bay has been home to a variety of lumber mills from at least 1888 to about 1968, according to the agreed order. The land contains several contaminants.

The city bought the land and will own the building for the new museum, which is expected to open by the end of 2011. The museum will provide the indoor and outdoor exhibits and staff.

The museum has proposed a 27,000-square-foot building and 30,000 square feet of outdoor space, replacing its current rented space at 106 11th Ave. S.W., which has about 10,400 square feet.

It is expected to cost $13.5 million for the land, site preparation and building; $4 million for exhibits; and $1 million for furnishing, fixtures and equipment. The city is paying $8.9 million for the museum, $7.9 million of which is from Public Facilities District dollars.

The city has set aside $675,000 for environmental cleanup costs on the museum site and $360,000 for a public plaza and reclaimed water feature – which the city will split the cost of with the LOTT Alliance, the regional sewer utility. Reclaimed water is treated water that is suitable for irrigation but not drinking.

The plaza, just smaller than an acre, will sit next to the museum and have a combination of hard and soft surfaces, landscaping and a small stage for events, said Eric Hielema, project manager for LOTT.

The budget for the plaza is $2.8 million, including construction and cleanup. The city is contributing $500,000 for construction in addition to cleanup. LOTT spokeswoman Karla Fowler said the museum would make a contribution.

Belmonte has said the museum’s indoor galleries are expected to open by the end of 2011, with the outdoor space to follow in 2012. The museum is courting major donors this year and will begin fundraising from the general public next year, she said.