Public workshops scheduled for Ala Wai flood risk abatement

The U.S. Army Corps of Engineers and the City and County of Honolulu are inviting the public to participate in the Ala Wai Canal Flood Risk Management General Reevaluation Study in a series of virtual “miniworkshops” next month.

Each of the four workshops, scheduled for April 1, 8, 14 and 22, will focus on a specific sub-basin of the Ala Wai watershed, addressing how to reduce the risk of flooding due to extreme rainstorms, which threatens the area’s 200,000 residents and schools and businesses, notably the economic hub of Waikiki.

“We’re now getting as much public input as we can, and we’ll take any idea from anybody and consider it,” said Alex Kozlov, director of the city Department of Design and Construction. “We’re starting with a clean sheet of paper; we haven’t decided at all what this is going to look like at the end of day.”

An earlier Marine Corps project proposal, which included building a 4-foot-high wall around the Ala Wai Canal and placing six large debris catchment and retention basins in the upper sections of Makiki, Manoa and Palolo streams, which drain into the canal, met with widespread community opposition in 2019 and was canceled after the withdrawal of $345 million in federal funding.

“Palolo Stream goes through my property, and the Army Corps wanted to condemn my property and put a catchment basin on it,” Honolulu resident Dave Watase, who opposed the plan, said Friday in a phone interview.

“We can build walls, but the (projected) 100-year storm may never happen in our lifetime, and every day we gotta look at (the walls),” Watase said.

“Or we can combine other ways, like underground tunnels, planting native trees, removing invasive trees and debris from streams,” he added, “and capture excess flow upstream, in conservation lands or parks, instead of letting it go down to the Ala Wai Canal and out into the ocean.”

In 2020 the Army Corps issued an engineering draft report for a new plan, which eliminated the much-­criticized upper watershed basins but kept three larger basins at Hausten Ditch, Kanewai Field and the Ala Wai Golf Course as well as the 4-foot walls around the canal.

That plan was also set aside.

Now “the corps is doing a complete reevaluation that is being fully funded with $3 million from the federal government, and will come up with a brand new conclusion,” Kozlov said, adding data and fieldwork from the previous studies were being incorporated.

Two workshops were held in November, and in January a “Management Measure Tracking Spreadsheet” was added to the project website, honolulu.gov/AlaWai, to collect ideas from the public.

As of Friday the spreadsheet had 202 unique suggestions, including adding tunnels, dredging, berms, surge barriers, bridge modifications and pump stations; preventing silt and debris from clogging streams; managing mountainside erosion; greening streets on the University of Hawaii at Manoa campus and directing floodwaters onto practice fields; replacing hard pavement with permeable surfaces that absorb runoff; adding “genki” bacteria balls and oysters to clean the Ala Wai Canal; adding a wall only to the Waikiki bank of the canal; adapting the Ala Wai golf course and district parks into wetlands and kalo patches; allowing school fields and business parking lots to serve as holding areas for diverted floodwaters; and much more.

More workshops in June will narrow down the ideas, Kozlov said, and give “a better idea of what the alternatives will look like.”

A tentatively selected plan will be discussed at public meetings in September, after which the Army Corps, with input from the city, will evaluate them and choose one plan by the fall of 2023.

If the city agrees to the plan, Kozlov said, funding will be sought.

Even if people speak in the workshops, Kozlov encouraged them to submit written comments via email to alawai@hawaii.gov or in the contact form on the project website. They can also comment and pinpoint specific watershed features on the website’s Crowdsource Reporter interactive map.

All these ideas are added to the spreadsheet, Kozlov said.

“If you want to be heard, write,” he said. “It’s really the best way.”

Watase said he is worried the Army Corps would choose a project to build flood mitigation structures without ecosystem restoration, and added, “If they want the community to work with them, they should do both at the same time.”

The city has been pursuing ecosystem restoration, said Matthew Gonser, chief resilience officer in the city Office of Climate Change, Sustainability and Resiliency.

“While historically some of our flood management practices were to channelize and get water out as quickly as possible, (now) we want to slow the water down, spread it out and soak it in,” he said.

The first priority is “a healthy native forest, which results in cleaner water and less flash flooding downstream, which we’re working on with DLNR’s Division of Forestry and Wildlife and the Board of Water Supply up in the conservation lands,” Gonser said.

A climate change concern expressed by the study is how sea level rise decreases the Ala Wai Canal’s capacity to contain stormwater.

The canal overflowed its banks and caused flooding in Waikiki during storms in 1965 and 1967, and Hurricane Iniki in 1992, according to the project website.

To attend the workshops, go to usace1.webex.com/meet/alawai or call 844-800-2712 and enter access code 1992629020. Advance sign-up is not required.

For more information and to comment, visit honolulu.gov/AlaWai.

GET INVOLVED

>> What: Public miniworkshops on how to prevent catastrophic flooding in Ala Wai watershed

>> When: Noon-1 p.m. April 1, 8, 14 and 22

>> Where: Attend virtually at usace1.webex.com/meet/alawai or call 844-800-2712 and enter access code 1992629020

>> For more info: Visit honolulu.gov/AlaWai