The city insisted Wednesday that its sewage system in Kakaako can handle new condominium tower projects in the area, but acknowledged that foul odors escaping the system are a problem that needs to be fixed.

Residents in Kakaako have complained for years about stench from underground wastewater lines with apparently little result.

Those complaints grew stronger in recent months after residents at One Waterfront Towers banded together to oppose a planned new condo called The Collection on an adjacent property, and said that an inadequate sewage system was one reason the project shouldn’t be approved.

The Hawaii Community Development Authority, a state agency overseeing development in Kakaako, approved The Collection in August while the city gave a tentative OK for connecting to the sewage system.

In response to the recent complaints, City Council members representing the area, Carol Fukunaga and Ann Kobayashi, introduced a resolution asking city officials responsible for the system to resolve the odor and capacity problems.

A hearing on the resolution was held Wednesday.

Guy Inouye, assistant chief of the city Department of Design and Construction’s Wastewater Division, said his department and the city Department of Environmental Services have formed a task force and hired engineering firm R.M. Towill Corp. to analyze and fix the odor problem.

A test is already planned to use a fan at the Ala Moana sewage pump station to remove odors from the system. Inouye said that test could be run later this year or early next year.

A potentially quicker fix could be installing one-way valves that prevent odors from backing through the system, he added.

More expensive solutions could involve installing giant p-traps in underground wastewater pipes. These traps are short U-shaped pipe segments that dip below the straight line and remain filled when a sewage flow stops to prevent air or odors from moving through an otherwise empty line.

Inouye said identifying what’s causing the problems is hard because Kakaako is above a nexus of sewer lines coming from other areas of the city on their way to pumping stations.

"It is such a difficult issue to deal with," he said.

Lori Kahikina, Environmental Services director, said her department is just as interested in finding a solution as Kakaako residents, though she said relatively few complaints were made to the department.

Kahikina said call logs show that 30 complaints were taken since 2006 from people complaining about sewage odors in Kakaako, and that, typically, crews were dispatched to seal manhole covers.

The source of complaints include callers from the Kapiolani area, central Kakaako, the Diamond Head end of Auahi Street and the area around One Waterfront, Kahikina said.

Sharon Moriwaki, a One Waterfront resident, disagreed that the city listened to complaints, saying that owners in her building sent a letter to Mayor Kirk Caldwell in June complaining about the situation.

A spokesman for the mayor issued a statement in response suggesting that the odor problems appeared to be tied to the plumbing infrastructure at One Waterfront.

Moriwaki was appreciative of the Council’s effort but said wastewater system hookups shouldn’t be approved for new residential towers, given the problem.

"It is a smelly situation that we have and it needs to be addressed," she said.