Changes To Honolulu Flood Project Raise Cost, Add Station

Nov 14, 2020

The U.S. Army Corps of Engineers has made significant changes to a Honolulu flood control project that would increase costs and add a four-story pump station.

A Corps official said updates to the Ala Wai Flood Risk Management Project focus on evacuating water in the upper reaches of watershed valleys without detaining it, The Honolulu Star-Advertiser reported Thursday.

Project Manager Jeff Herzog said the updates to the project on the city’s historic Ala Wai Canal would decrease the impact on residential properties and natural streams.

Previous Corps designs estimated costs of $345 million, with the state paying $121 million and federal funds covering the rest. The new plan is estimated at about $376 million with a $48 million contingency.

The project stalled last year after opposition from members of the community, which included protests, a lawsuit and the formation of an interaction group sanctioned by the Honolulu City Council.

The project was renewed after the Corps obtained federal approval in August for an Engineering Documentation Report implementing design changes and new features.

Herzog told a Waikiki Neighborhood Board meeting Tuesday that the new proposal presents alternatives to a 2017 plan.

The changes include conveying flood waters through the Manoa watershed and the Ala Wai Canal and addressing potential effects associated with redirecting flood waters at Manoa Marketplace.

The plan also would consolidate two pump stations into a single station at the Ala Wai Golf Course and eliminate six detention basins in the upper watershed.

“We’re looking at one piece of the puzzle,” Herzog said. “It’s important to involve the community as well as our partners at the state and the city and county to ensure that we can make this project holistically acceptable to the community.”

Public input will be incorporated into a supplemental environmental assessment, which Herzog said the Corps expects to release in February. The assessment is required under the National Environmental Policy Act and Hawaii Environmental Policy Act.

Rather than adding a pump station or erecting canal walls, Honolulu City Councilwoman Ann Kobaysahi said she hopes the Corps will incorporate a proposal from the city’s technical consultant, Oceanit Laboratories Inc.

The company recommended constructing two 12-foot (3.7-meter) tunnels to bypass the lower watershed and the Ala Wai Canal and discharge water into the ocean.

“If we do this tunnel thing it’s about the same cost and there won’t be all this ugliness," Kobayashi said.

The Corps plans a series of public meetings before publishing and asking for public comment on the supplemental environmental assessment report on the project. 

The first of two environmental impacts scoping meetings is today from 8 a.m. to 10 a.m. and the second at the same time on Nov. 21. Two design and engineering forums will follow on Nov. 28 and Dec. 5, 8 a.m. to 11 a.m.

The public can participate virtually by logging on to or calling 1-844-800-2712 using the access code: 199 126 8738# and security code 1234#.

The HPR news staff contributed to this report.