A 2.1-mile sewer overflow tunnel being built under William J. Day Boulevard may be hitting a speed bump, as a key Columbia Point landowner is raising a stink over a planned odor control facility nearby.

The Corcoran Jennison Companies, owner of the Bayside Exposition Center, is planning on hitting local neighborhood civic associations with its concerns on the single-story brick structure, known as an odor control facility, set to be built behind the State Police barracks.

The odor control facility, due to be built this summer and fully working by 2010, is at one end of the tunnel the Massachusetts Water Resources Authority is building, with a pumping station at the other at Conley Terminal in South Boston.

Corcoran Jennison officials say the facility can be designed to keep a lower profile, be more environmentally friendly and operate better during peak periods. The company is also asking for state Department of Environmental Protection oversight.

The requests have left MWRA staffers nonplussed, with the quasi-public agency coming out swinging at Tuesday night's meeting of the McCormack Civic Association (MCA).

"This isn't the eleventh hour to bring this up. This is five seconds to midnight," said Jeff McLaughlin, the MWRA's community relations coordinator. "It's a bit surprising to the MWRA that people have this concern."

Corcoran Jennison officials also say they only specifically learned of the odor facility last year, a claim MWRA staffers dispute. Staffers brought with them a collection of press clips on the tunnel project and a timeline of meetings on the project with a number of neighborhood groups and Corcoran Jennison.

"We've been meeting with people all along on this project," McLaughlin said.

They also disagree on whether the facility will generate an odor. Corcoran Jennison said the odor could waft up and throughout the area, while MWRA staffers say there will be no odor at all.

Corcoran Jennison representatives were not able to make the MCA meeting on Tuesday, but their director of community relations, Catherine O'Neill, told the Reporter, "It's a great deal of concern to us. We think it can work better."

The tunnel project, started about two months ago, is now about 20 percent complete. A $10 million boring machine from Japan has recently been installed in a location under Farragut Road. The project is meant to reduce beach closings after heavy rains, which often cause sewage and storm water to get dumped into the harbor and beaches some twenty times a year. The state Department of Conservation and Recreation has had to close beaches eight times every swimming season due to the pollution from the sewage and storm water.

With the tunnel in place, sewage, instead of getting sent into the bay, will be collected and pumped out to Deer Island for treatment.

Heavy electric fans housed in the odor control facility, with 8-foot blades, will draw the air out of the tunnel. The air will then be purified with carbon filters.

If Tuesday night's MCA meeting is any indication, Corcoran Jennison may have an uphill battle on their hands. Members of the civic association had few questions about the project, including whether the fans will be too loud. McLaughlin said he has not heard any neighborhood complaints about a similar facility already in use near Union Park in the South End.

Local politicians have also come out in favor of the tunnel project, pointing to its potential to clean up beaches from Castle Island to Dorchester Bay.

MWRA staffers also acknowledged that an "emission control" facility may be a better name, instead of "odor control," and say the project has gotten the necessary permits, and does not need the DEP oversight that the agency agreed to submit to back in 1999.

MWRA staffers say they're open to design changes and adjustments, but add that the project has never changed, while Corcoran Jennison, responding to the the loss of gate shows at Bayside, have plans to demolish and replace it with a new neighborhood of housing and retail buildings.

"We're doing what we can to appease them," McLaughlin said.