Sen. Daniel K. Inouye said during a Good Friday walking tour of flood-ravaged Round Top Drive yesterday that he could secure $1 million in emergency federal assistance to open a closed quarter-mile section of the road.

"I guarantee it," Hawai'i's senior U.S. senator told Honolulu Mayor Mufi Hannemann, who led the tour, trailed by a contingent of reporters, photographers, local politicos, Maunalaha Valley residents and numerous city and state agency representatives.

To do it, Inouye said, he would need to set aside an equal amount of money from other projects, although he would not say what those projects might be.

Inouye said the issue isn't a matter of if the work should or should not be done. The fact is, he said, that the road must be fixed, "unless you want to close this up and just have a mountain here."

Inouye also said he believed he should be able to get additional federal money to help pay for an estimated $15 million to $20 million city/state plan to reroute the drive and shore up the mountain above, which unleashed tons of mud and debris across the road and into the valley during the heavy rains of March.

"The major development here is that you have the city and state working together," he said. "It would be a terrible thing if the state had one plan and the city had another. And how do I go before the Congress? This way I can go, and they'll be speaking in one voice."

Valley residents who live in the path of the debris flow said they were encouraged by the senator's remarks.

Coco Needham, who has lived in the valley all her life and is a member of the Maunalaha Valley Community Association, said she and her neighbors have never seen anything that equals the March rains and the resulting mudslides.

Needham said she and other association members would be doing their own damage assessments, but they generally were pleased by the senator's assurances. "It gave us a sense of hope, that the city and state are working together with the federal government," she said.

Hannemann said the long-term project would be for the state to stabilize the mountain slope and the city to reroute Round Top Drive by building a switchback road.

"That means we would basically construct the road whereby it wouldn't go through the damage area," Hannemann explained. "We would have it curve around" and move through an area that's naturally stable.

Hannemann said the city's cost estimate for the switchback road would be $7 million to $10 million.

That's roughly the same amount Maj. Gen. Robert Lee, state director of civil defense, estimated the state Department of Land and Natural Resources would need to spend to shore up the mountain slope.

The state, which owns the land above Round Top Drive, would first find the source of the debris flow, shore it up, and build retaining walls to capture debris slides in the future, Lee said.

"We've got a plan that I think is pretty good," he said.

During the walking tour, Hannemann and officials from his office also showed the senator a map outlining Waikiki's crumbling sewage infrastructure, which resulted in nearly 50 million gallons of raw sewage going into the Ala Wai Canal when a force main broke in March.

Inouye, D-Hawai'i, said he may be able to get federal assistance on that as well.

"From what I've seen in a few minutes here, it would appear to me that a major player would be the Department of Defense," he said. "Because one of the major beneficiaries would be Fort De Russy."

Inouye said he will be spending time today discussing the matter with Defense Department officials.

Meanwhile, Round Top Drive resident Kats Uehara said she and her neighbors would be watching the hillside and sleeping with one eye open.

"The real sad part is that all of us who live here have learned to love the rain," she said. "To hear it at night has always been very soothing. We all would sleep very well. Now, that's not the same."

Reach Will Hoover at whoover@honoluluadvertiser.com.