PORTLAND  Driving around Back Cove and on Forest Avenue is about to get complicated.

A $10 million sewer improvement project that’s intended to clean up Back Cove will begin Wednesday, closing much of Baxter Boulevard for an estimated eight months.

The roughly 1.4-mile stretch of Baxter Boulevard from Vannah Avenue to Bates Street will be closed to all traffic. The stretch from Preble Street to Vannah Avenue will be open only to local traffic.

Drivers are encouraged to avoid the area by using Interstate 295, Brighton Avenue or Riverside Street.

Pedestrians, runners and bicyclists will continue to have access to the trail system.

City officials have been meeting with residents and warning motorists, and are reserving some nearby roads for local traffic only. City Councilor Cheryl Leeman, whose district includes the neighborhood, said the city will keep a close eye on traffic, especially along Vannah Avenue, which has the potential to become a cut-through route to Ocean Avenue.

“We’ll just monitor the traffic, and if it gets to be a problem we’ll have to take some corrective action,” Leeman said.

The project includes the installation of two million-gallon underground storage tanks to capture untreated sewage and stormwater, which now is released into Back Cove whenever a rainstorm floods the combined sewers and the system overflows.

One tank will be installed beneath Baxter Boulevard. The other will go under Payson Park.

The city has been under a federal order to fix its stormwater system since the 1990s. It recently adopted a $170 million plan to reduce sewer overflows by 87 million gallons a year.

To this point, the city has mostly separated sewer pipes from stormwater pipes to reduce overflows into Casco Bay during rainstorms. Although such separation projects remove the sewage, they still allow polluted runoff to overflow into the bay.

The underground storage tanks along Baxter Boulevard will capture both sewage and stormwater overflows until rainstorms pass and the East End treatment plant has the capacity to treat the polluted water.

“It’s a better strategy than separation,” said Baykeeper Joe Payne, a clean-water advocate with the Friends of Casco Bay.

The city has held several public meetings about the project, so drivers should not be surprised that the road is closed, say city and neighborhood leaders.

Tom Landry, president of the Back Cove Neighborhood Association, credited the city’s education efforts for the preparedness of residents, who understand that the inconvenience is necessary.

“In order to get this done, there has to be some level of inconvenience,” he said.

In 2010, an average of 9,430 vehicles a day traveled on Baxter Boulevard near Vannah Avenue, according to figures from the Maine Department of Transportation.

The eight-month closure will likely send more traffic to heavily traveled Woodford’s Corner, where Forest Avenue intersects with Woodford Street and Ocean Avenue.

An average of more than 22,850 vehicles a day passed through Woodford’s Corner on Forest Avenue in 2010, according to state data.

The city considered removing some on-street parking at the intersection to accommodate the increase in traffic.

That would have been in line with a recommendation in the recent “Transforming Forest Avenue” study, which would have banned parking along the northbound lane of Forest Avenue from Woodford Street to Ocean Avenue to allow for another travel lane during rush hour.

A meeting scheduled last week to discuss the proposal with business owners was canceled when Leeman reminded the staff that those changes could not be made without a comprehensive traffic and engineering study.

“It is extremely detrimental to all the businesses there, because that’s their key parking,” Leeman said.

Landry said residents and commuters should plan ahead and alter their commuting schedules when possible to avoid delays.

“If you can commute a half an hour different, if you can prevent the rush hour stuff from happening, you can avoid a lot of these problems,” he said.

Payne, the baykeeper, wants people to know that any inconvenience is for a good cause.

“It’s unfortunate it is going to cause a disruption in traffic and inconvenience some people,” he said. “But I hope they would agree it’s for the greater good and it’s going to make a significant difference in the health of the Back Cove and all the critters that live in it.”

Staff Writer Randy Billings can be contacted at 791-6346 or at:

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Twitter: @randybillings