PORTLAND — The city on Monday began installing the first of two massive underground conduits designed to prevent sewage from overflowing into Back Cove.
The conduits will each be able to temporarily store about 1 million gallons of combined sewage and storm water until the mixture can be piped to the waste-water facility in the East End for treatment.
The conduits – basically, long concrete boxes – will run for a total of about 3,000 feet along Baxter Boulevard and also under Payson Park, toward Front Street. A 1.4-mile portion of the boulevard, from Bates Street to Vannah Avenue, has been closed to vehicle traffic since Jan. 30 to accommodate the construction.
The street is not expected to open again until the $10 million project, funded by sewer user fees, is complete in October.
Mayor Michael Brennan, Director of Public Services Michael Bobinsky, state officials and environmental advocates spoke as workers prepared to lower a section of the conduit into the ground.
“Obviously, (the boulevard closure) is an inconvenience,” Brennan said, “but it truly is for the greater good.”
Joe Payne, of the Friends of Casco Bay advocacy group, agreed.
“This project is preventing hundreds or thousands of cars a day from using Baxter Boulevard, but it’s also going to prevent millions of gallons of (waste water) from going into Casco Bay,” said Payne, the group’s baykeeper.
More than half of the city’s 200 miles of sewer pipes combine sewage and storm water into a single drainage system. Some of the pipes were built of brick around the time of the Civil War. The system often overflows during heavy rains and snow melts, sending waste water – including the potentially harmful raw sewage – into nearby waterways.
There are 31 locations in the city where these “combined sewer overflows” occur regularly and are legally permitted by the state Department of Environmental Protection, according to a DEP memo. Three of the locations are along the boulevard.
The CSO locations in Portland comprise about one-fifth of all the locations in Maine, and accounted for 39 percent of the total CSO amounts in 2010.
Under a 1991 consent agreement with DEP, the city is required to fix the trouble spots and bring them into compliance with U.S. Environmental Protection Agency regulations.
Since 1993, the city has spent nearly $100 million on efforts to reduce sewer overflows, according to a press release, including projects to separate the combined sewer and storm-water lines. In that time, the discharged amounts have dropped 42 percent, from 720 millions gallons annually to 420 million gallons.
Next year, the city will begin another $170 million set of projects to reduce sewer overflow volumes to 87 million gallons annually.
In addition, the city agreed last week to pay more than $53,000 in penalties to EPA for illegal sewage discharges between 2007 and 2009.
Concrete worker Walter May prepares to unload a 22,000-pound conduit section on Baxter Boulevard Monday. Two underground conduits, running 3,000 feet along the boulevard and Payson Park, will hold up to 2 million gallons of sewage and storm water.