Some $75 million worth of upgrades are under way — or are about to begin — on the half-century-old sewer system in Kailua and Kane'ohe, and worried residents hope that all of the disruptions will be worth the trouble.

Sookhee Son, the owner of Michael's Liquor, saw sales suddenly drop 50 percent last week when workers began closing Kailua Road right in front of her business for seven hours each day for the next six weeks.

"It's really affected us a lot," she said. "I really worry what's going to happen to business."

Four sewer renovation projects have already begun beneath the streets of Kailua and Kane'ohe, and another four are scheduled to start this summer and fall — almost all of them in Kailua.

The work represents 20 percent of all sewer projects on the island, said Russell Takara, deputy director of the city's Design and Construction Department.

Residents won't see any increase in sewer capacity when all eight projects are finished by 2010. Nor will there be any reduction in raw sewage that spills onto streets, beaches and the ocean when heavy rains overload the system.

"We're trying to clean up our aging infrastructure," Takara said. "The normal guy who doesn't have problems won't see a difference."

But the work is necessary, Takara said, to repair and replace aging and broken pipes and prevent more spills.

The work on the Windward side of the island is part of $1.5 billion in sewer repairs already completed on O'ahu, which will see $1 billion more worth of sewer projects through 2013 and 2014.

"We've got tons of sewer work going around the island," Takara said. "Overall, we're putting a lot of money into getting our aging sewer system fixed."

Other communities are seeing similar work in their neighborhoods. But people in Kailua are especially nervous because what was to be a three-year, $36 million sewer project on beachfront Kalaheo Avenue ended up disrupting traffic for seven years at a cost of $58.5 million.

Virginia Enos, a member of the Kailua Neighborhood Board, wants a sewer system "that quits choking our lifestyle and keeps our ocean clean."

But she sees increasingly congested traffic being disrupted by sewer repairs and says the quality of life is going down in Kailua as a result.

"We've been through a nightmare in Kailua, and I hope the city learned its lesson," Enos said. "We're not getting our money's worth here. I can't figure for the life of me why we can't build a good sewer system — just as we can't fill a pothole — without a struggle."

City officials are well aware of the concerns over the Kalaheo Avenue project, which was finally finished last year. Mayor Mufi Hannemann, in fact, announced its completion in his State of the City address, to raucous applause.

The work choked traffic along one of the major roads that takes people across Kailua — and Takara said officials worry that current projects will also block traffic.

"We try to avoid road closures as much as possible," he said. "However, in specific instances (such as the Kailua Road project) ... we could not avoid having to close the road due to safety concerns."

Tiny Michael's Liquor is the only business in the 200-yard stretch of Kailua Road between Hahani and Aoloa streets that's now cut off entirely from vehicle traffic for at least a portion of each day.

But one entrance to the nearby Aloha gas station also gets blocked during the day.

"Let's get it done quickly," said Evan Scherman, first vice president of the Kailua Chamber of Commerce. "Anytime business gets affected, it's never a good thing."

He drove through a strip mall near Michael's Liquor and said, "It's just too humbug to get in there."

"I live and work in this town, and it's frustrating for everyone involved," Scherman said. "If I knew the improvements being made actually helped in some way, I'd be more sympathetic to all of the construction. But how sympathetic can you be when roads are closed and we're not adding any more capacity?"