The neighbors haven’t exactly welcomed it with open arms, but the project that will drill a $200 million tunnel to transport sewage from Kaneohe to Kailua is underway.
The largest gravity-flow tunnel in Hawaii history is part of the city’s ongoing efforts to improve its sewer system and comply with a $3.5 billion consent decree resulting from lawsuits claiming the system is flawed.
City officials announced the start of construction Friday, saying the new 3-mile tunnel will not only move wastewater, but offer enough storage space to prevent overflows and spills, especially during storms.
Area residents have been worried about how the construction will affect them, registering concerns about noise and related issues.
"A lot of us were very negative in the beginning," said Gary Weller, a member of the Kailua Neighborhood Board, "but the city has gone out of its way to try to mitigate all those problems. We’re all very hopeful the odor will go away and that the sewage plant will not have to dump sewage into the ocean. Because when this plant gets overwhelmed by water, that’s what they have to do."
Along with a separate odor-control project, residents are hopeful the Kailua Regional Wastewater Treatment Plant will become a better neighbor, Weller said.
"We’re still in the wait-and-see mode, but we’re way happier than we were, let’s just say, a bunch of years ago," he said.
Honolulu Mayor Kirk Caldwell said the tunnel will stimulate jobs, provide benefits to the environment and serve Windward neighborhoods with a safe and out-of-sight wastewater system.
The tunnel will eliminate above-ground wastewater storage, reduce overall costs and preserve Kaneohe Bay, Caldwell said.
"It means that we’re saving energy. It means that we’re becoming a greener community. It means we have larger capacity," the mayor said in a ceremony at the Kailua plant, where tunnel-boring will begin in March and is expected to be completed by June 2018.
It will replace the existing, smaller pipeline, a 42-inch force main that travels underneath coastal neighborhoods in Kaneohe.
The new tunnel will head underneath the Oneawa Hills, cross under the H-3 freeway and then under Kaneohe Bay Drive before ending at the Kaneohe Wastewater Treatment Plant. Relying on gravity, the tunnel will lie 35 feet below ground in Kaneohe and descend to about 62 feet below ground in Kailua. At one point in the Oneawa Hills, it will be as much as 400 feet underground.
Doing the digging will be a 160-ton high-tech tunnel-boring machine that has a diameter of 13 feet.
Officials said the designers of the project used the same technology for a similar project in a sensitive neighborhood in San Francisco. The machine worked at a depth of 100 feet, and the residents, they said, had no idea tunnel construction was taking place.
More than 90 percent of the Kaneohe-to-Kailua tunnel will be deeper than 100 feet, they said.
A number of public meetings have been held to address the Kaneohe-to-Kailua project. In response to concerns from residents, officials moved the alignment of the tunnel farther away from homes.
Also, plans are in the works for a monitoring program to record ground movement, noise and vibration during and after construction.
Above-ground construction will be limited to the city wastewater plants in Kaneohe and Kailua, where sound reduction equipment, construction walls and a traffic management plan are in place.
Next year the city will start on the project’s second phase: a $100,000 pump station to treat the sewage transported by the new resin-lined tunnel.
In 2010 the city agreed to make more than $3.5 billion in improvements to its sewage treatment system and pay a $1.6 million fine. The consent decree was with the U.S. Environmental Protection Agency, the state Department of Health and three environmental groups that had sued the city.
The fine was intended to resolve violations of federal and state law for past sewage spills, such as when a sewer main break forced the city to discharge about 50 million gallons of sewage into the Ala Wai Canal in 2006.
As a result of the consent decree, the city will upgrade its wastewater collection system and treatment plants over the next 25 years or so.
