Kailua residents are bracing for another lengthy sewer project on a major road and all the noise, dust and traffic problems that come with it.

The city plans to replace 50-year-old sewer pipes along a stretch of Keolu Drive and Wana'ao Road in Enchanted Lake. But before the $29.5 million project can start early next year, officials need public input on a draft environmental assessment.

The project to install larger pipes ranging from 12 inches to 42 inches in diameter could take up to 2 1/2 years to complete.

The public has until March 10 to comment on the assessment.

Convincing Kailua residents that the job can be finished quickly may be a tough sell, especially after several years of similar projects.

Crews have been working on Kalaheo Avenue since 1999 on a job that was only supposed to last three years. That is scheduled for completion by October.

And sewer reconstruction on Kainehe Street, Hamakua Drive and a section of Keolu Drive, begun in 2002, should be finished this month.

Barbara Wright, who lives on Wana'ao, said with a chuckle that city equipment in the middle of Kailua streets "looks permanent."

"These people are not in it for speed," she said. "I think they are in this for a career. It will take longer. Always add on a year or so when any governmental agency tells you a date — and then you will still be disappointed."

The sewer system along Keolu Drive and Wana'ao Road that is slated to be replaced was built in 1956 and isn't aging well, according to the city. Fixing it involves replacing sewer pipes that no longer allow gravity to help fluids flow in the right direction, have corroded to the point that rebar is exposed and require constant maintenance to remove grease, grit and debris or risk sewage spills.

"Eventually, the lines deteriorate," said Eldon Franklin, wastewater division chief for the city's Department of Design and Construction. "If they collapse, it's like what happened on both Kalaeho Avenue and Hamakua Drive — you have holes open up. And that's dangerous. If you get high-rainfall events, you have sewage spills and that impacts health and safety."

Sewer construction work typically is limited to non-peak traffic hours — between 8:30 a.m. and 3 p.m. — but the city wants to extend that by several hours, according to the draft environmental assessment. Weekday crews would work until 6 p.m. unless they were near the shopping centers, where they would stop at 5 p.m.

The city said this is needed to reduce public inconvenience and cut costs. Without it, the job could take an additional six months to finish, Franklin said.

"It's very inefficient to button up early and then get all the equipment out again," he said. "You just get more productivity with that little bit of effort."

Some work must be done on weekends and some machinery must occasionally operate overnight, he said.

Work will begin where Akalani Loop and Akahai Street meet Keolu Drive and proceed through the Enchanted Lake business district before turning right on Wana'ao Road and going until it reaches a wastewater pumping station at 'Auwina Street.

That route takes construction past two shopping centers, a movie theater, several gas stations, a church and church school and homes nearly as old as the sewer pipes.

Iwalani Keawe has lived on Wana'ao Road nearly as long as the pipes below it — 41 years.

"I can understand their needing to do it," she said. "But I just hope they hurry up and do it and leave. "

Keawe fears that the difficult left turn out of her driveway will become more dangerous once construction reaches her home and fills the road with equipment.

But children walking home from Enchanted Lake Elementary face a greater problem, she said, because they're "going to have a hard time crossing the street."

Reach Mike Gordon at mgordon@honoluluadvertiser.com.