HONOLULU (KHON2) — Projects that cost tens of billions of dollars. That could be the price tag of hardening and updating Hawaii’s critical infrastructure to combat the impacts of climate change.

Hawaii is looking at projected sea level rises, changes in rain patterns, and severe storms.

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“Right now we designed for 100-year storms but areas are getting flooded designed for 100-year storms,” Department of Transportation Deputy Director of Highways Ed Sniffen said.

The DOT said they are pushing forward on vulnerability studies on the state highways to ensure they can understand exactly where they are vulnerable and start mitigating systematically. They said they have a climate adaptation action plan to ensure that any time they start moving forward on projects and initiatives they are always considering resiliency.

“For us, that’s the $15 billion dollar question. When we start talking about things 20 percent of our roadways will be inundated by (the year) 2100, and not only that if you look at the mountainsides there’s 10 percent of our roadways that are impacted by rock fall,” Sniffen said.

We’re already seeing impacts of erosion with homes on Oahu’s north shore,

“On the north shore, we have to make tough decisions what do we do about homes that are falling into the ocean on the north shore. Do we harden those shorelines or do we move back coastal highways?” Hawaii’s Congressional District 2 Representative Kai Kahele said.

This weekend’s road closure in Kahana is just a taste of what climate change could bring to a number of shoreline roads across the state. For now, the DOT is using crushed rock and bags to dissipate energy coming in to protect roads.

“That’s a 10-year solution that’s just a band-aid in the long scheme of things,” Sniffen said. “That 10 years is super important for us because we need to understand what land use is going to look like in the future,”

For now, it’s unknown. Sniffen says he’ll meet with city and state planning agencies as sea levels rise to determine what is best for allocating resources in places like Kamehameha Highway, where one option is moving the road up the mountain at a cost of around $1.5 billion.

“Long-term that portion of the highway that 10-mile section between Kaawa and Hauula is gone. It’s going to be inundated it’s going to be flooded by 2100. That roadway you consider is about a foot higher than a lot of the homes we service in those areas. So in general what makes me think if the roads gone what makes me think those houses will be there?”

Once the highways are made or finalized, then water mains can follow.

The Honolulu Board of Water Supply has partnered with University of Hawaii professors and the water research foundation, a national organization that’s set up to research across the country in water resources including climate change. The research projected global climate models onto Oahu’s atmosphere, finding that areas like the Waianae mountains could see drier conditions.

BWS Manager and Chief Engineer Ernie Lau says the uncertainty makes the BWS have to be nimble with what to do with 2,100 miles of water mains. Honolulu’s water mains are currently being replaced. Metal pipes are stronger to use than PVC, but more prone to corrosion the more they’re exposed to salt water.

“The water underground will start to rise and the pipes might be submerged part of the time or all of the time. So some of the challenges are some operational challenges, when we have a main break how do we do a repair do we have to wait for low tide?” Lau said.

The Board of Water Supply is working on making them more resilient with bonded coating and electrical charges.

“This new standard that we have for metal pipe to protect it will prolong the life of the pipe hopefully get us that 100 years of service,” Lau said.

The state is set to get $2.8 billion from the federal infrastructure bill to help get it all done, but Sniffen says that won’t be enough.

“It’s tremendous,” Sniffen said. “But there are discretionary grants that total up to about $50 billion that we can apply for and that could be life-changing for Hawaii. We’re being really aggressive in applying for those discretionary grants to make sure we can get as much to Hawaii to update what we made sooner rather than later.”

He adds that Hawaii’s county, state, and federal government leaders will need to work in harmony as time is of the essence.

This comes as new legislation to combat climate change from President Biden and congressional Democrats was stonewalled by Democratic Senator Joe Manchin. Rep. Kahele said the move puts more pressure on the state to act.

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“This is going to be a lot of money that’s going to fund these projects,” Kahele said. “We’re going to need every bit that we can get, so ensuring that Hawaii has a solid relationship with Washington D.C. with the congressional delegation is really important.”