More than three years after fast-moving floodwaters rushed into some 120 Manoa homes and the University of Hawai'i campus, causing more than $85 million in damage, the state is kicking off a project to increase water capacity and improve flow under Woodlawn Bridge.

The project is the first in what is expected to be a series of major flood-mitigation efforts for Manoa Stream over the next two decades.

But residents won't see changes over-night.

Though the design phase of the Woodlawn Bridge project started this month, construction won't begin until December 2009 because of required federal approvals and environmental reviews. The project is expected to wrap up by late 2010.

Other projects — especially those designed to guard against bigger flooding events in Manoa — are even further in the future.

Residents are frustrated by the pace of work but relieved officials are finally doing something. They also say Woodlawn Bridge, where water overtopped the banks of Manoa Stream on Oct. 30, 2004, rushed through Noelani Elementary School, into homes and then onto the University of Hawai'i campus, is a good place to start — but not the only point of concern.

"It's not just the bridge," said Annie Yokoyama, who spent more than $60,000 repairing her Pamoa Road home, behind Noelani Elementary, after the flood. "It's Manoa Stream all the way up to the mountains."

The Manoa flood of 2004 was spurred by a combination of unusually heavy rains and debris-laden streambeds, officials have determined.

A U.S. Army Corps of Engineers report released this year said some flooding still would have occurred — as far down as the UH campus — even if the streambeds were cleared.

STREAMBED RAMP

The conclusion raised concerns for many residents and increased the call for flood-mitigation efforts along Manoa Stream. Until now, the only big improvements to the stream have been dredging and clearing debris — largely by the city.

The $2.8 million project near Woodlawn Bridge, covered mostly with federal funds, will install a 4-foot ramp — "or drop structure" — on the streambed to speed up water as it moves under the bridge, decreasing the chance of overflows during heavy rains. The project will also include dredging and lining the streambed with "grouted rubble paving" to stop debris and sediments from accumulating.

State Rep. Kirk Caldwell, whose district includes Manoa, said the Woodlawn project is a "midterm" flood-mitigation effort that will hopefully reduce the risk of another 25-year flood like the 2004 event. Other mid-term proposals, which are not as far along, include installing a wall near Lowrey Bridge and raising a flood wall on East Manoa Road, Caldwell said.

For more long-term fixes, officials and residents are looking to the Army Corps of Engineers, which is in the midst of a massive flood zone study that includes an analysis of Manoa Stream. The report is expected to be released in mid-2010 and will open the door to millions of dollars in federal funding for flood-mitigation efforts in urban Honolulu.

Derek Chow, chief of the civil and public works branch at the Army Corps of Engineers, said construction on flood-mitigation projects proposed in the study could start by 2013 — if federal funding comes through.

Though much of the attention of the report is centered on Waikiki, where a 100-year flood could not only cost millions in damages but potentially cripple the state's economy, Chow said the report is assessing possible long-term flood-mitigation fixes in Makiki, Palolo and Manoa, where the water that heads to Ala Moana and Waikiki comes from.

LONG-TERM FIXES

Chow said long-term measures for Manoa Stream could center on increasing the capacity of the waterway or reducing flow by holding water in the mountains during heavy rains.

Scott Wilson, president of Malama o Manoa, a nonprofit dedicated to preserving historic Manoa Valley, said some residents are concerned the long-term fixes will take away from the natural beauty of Manoa Stream.

"We don't want Manoa Stream turned into a concrete culvert," Wilson said. "We want to preserve a natural streambed."

Meanwhile, Wilson said the ramp proposal at Woodlawn Bridge appears to have little impact and offers significant benefit. But he added that it's important officials don't just take the short view, either. "I'm concerned that we don't try to just spot-treat things," he said.

Eric Hirano, chief engineer with the state Department of Land and Natural Resources, said the Woodlawn project requires a review by FEMA, which is providing much of the construction funds as part of a hazard-mitigation program. The state is pitching in about $700,000 for the project.

The work will also require either an environmental assessment or more lengthy environmental impact statement depending on how the ramp affects downstream waters.

Hirano said it took so long for the state to start the project because officials had to wait until damages from the flood were tallied. The DLNR turned in its application for the FEMA funds in July 2006 and then sought funding from the Legislature.

The city is working with the state and FEMA on the project but is not putting in any money.

Though the 2004 flood rushed through dozens of homes, topping stream banks at Manoa District Park and Woodlawn Bridge, the most costly damage was at the University of Hawai'i campus. The flood destroyed labs and the basement of Hamilton Library, which is still undergoing repairs.

Gregg Takayama, spokesman for the university, said officials are trying to reduce the chances of another flood causing major damage, but added there is only so much they can do.

He said a so-called moat around the Hamilton Library basement will be filled in to decrease the chances of water flooding basement collections again. And the library's generator, which was in the basement, will be positioned outside the building. The work will be finished by June 2009.

On Pamoa Road, just outside the campus, residents don't have the option of putting up barriers around their homes to keep water out. All they can do is wait and worry every time it rains.

Several said they drive to Woodlawn Bridge during heavy downpours just to see how high the water is. "It's always in the back of our minds," said Yokoyama, whose home sustained major damage in the flood. And, added the mother of three, until a flood-mitigation effort offers a good fix, it will continue to be.

Reach Mary Vorsino at mvorsino@honoluluadvertiser.com.

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