HANALEI — An irrigation tunnel played a big part in the Thursday-morning collapse of the slope on an area called Hanalei Hill, burying a portion of Kuhio Highway above the Hanalei Bridge.
Water and soil continue to come off of the slope, according to the state Department of Transportation, which has been monitoring the hillside.
The landslide has closed Kuhio Highway in both directions, effectively cutting off the only land access to Hanalei and areas west of the town.
DOT staff members had been monitoring the slope for several days, clearing away some debris that was shaking loose onto the highway, and were on scene directly after the landslide, which occurred at about 11 a.m. on Thursday.
DOT Highways Division Deputy Director Ed Sniffen said crews were in the area early Thursday morning, clearing away rockfall debris that was already littering the highway.
“Soon after, that (whole) slope in general came down,” Sniffen said.
The part of the slope that fell onto the highway isn’t exactly in the same place as the 2018 landslide that temporarily closed the road, but it’s nearby.
DOT-contracted crews spent months working on the hill in the area of the 2018 landslide, securing it with metal mesh and rock fencing at the bottom. The current situation is a bit different than the 2018 landslide, though, he said.
“Isn’t nearly as wide as the one from before,” Sniffen said. “But it’s much deeper. So it was four to five feet of the material from the slope, it came down.
Photos taken of the site from the air and then distributed on social media show a hole at the top portion of the hill that Sniffen said as an irrigation tunnel — a tunnel that pushed water out in a more-concentrated stream than in other places on the hillside.
“That water is coming out and it’s saturating the slope below it,” Sniffen said. “Typically, when you see this rain falling, it’ll fall at different locations of the slope, which causes the surface material to come down. Because it’s saturated at a specific point, for a long period of time it caused that deeper failure in that area.”
DOT did some preliminary investigations on Thursday in the area, placing benchmarks on the upper road so they can monitor any further landslide activity, clearing debris and cutting trees on the upper slope to help direct water away from the landslide. But further assessment is needed to know which next steps to take.
“We’re hoping that by tomorrow (Friday) the slope will be dry enough that we can start excavating the materials to start checking things out,” Sniffen said.
Today, the team will also attempt to see the condition of the highway itself and determine if the slope is stable enough to considering opening Kuhio Highway in that area.
“If all we need to do is move debris and change the slope, we could potentially have the road open by Tuesday,” Sniffen said, pointing out it could take weeks or months to get the road open, depending upon how much slope-stabilization is needed.
Meanwhile, a single lane remained closed Thursday at Waikoko, near mile marker 4.5, due to falling debris. And Kuhio Highway between Kolopua Apartments and Hanalei Plantation Road remains closed out of an abundance of caution. The area will be assessed.
Thursday, Mayor Derek Kawakami advised North Shore residents to shelter in place, stay off the roads and stay tuned into updates, especially since more rain is expected and Kaua‘i is under a flash-flood watch until 6 p.m. today as of press time Thursday.
“Our North Shore community has been through so much over the years, and again they are called to overcome a great challenge with many unknowns at this time,” Kawakami said. “We want to assure our residents and visitors that we will get through this together.”
First responders have been mobilized in the area and are also able to access the North Shore community by boat and Air 1 operations for emergencies.
Due to limited access, the Ke‘e and Ha‘ena beach park towers are currently closed. Lifeguards on the north roving unit are monitoring Hanalei Bay and are available to respond if necessary.
The state Department of Education said Hanalei School is closed.
Kaua‘i Island Utility Cooperative members from Hanalei to Ha‘ena are advised to prepare for extended periods without power if outages occur while Kuhio Highway remains closed.
“We’re working on contingency plans to be able to get our trucks to these areas if there are outages. However it will be challenging,” ssaid KIUC Chief of Operations Brad Rockwell.
“Access via helicopter will be limited by weather conditions. We’ll use all available means of communication to keep members informed about current outages, safety alerts and timeframes for restoration, if known,” he said.
The KIUC Facebook page is providing status reports, and the outage map on the homepage of the cooperative’s website is another resource for current information: kiuc.coop.
For updates on road conditions and closures, call 241-1725. Do not call 911 unless there is an actual emergency.
For weather updates, call the National Weather Service automated weather line at 245-6001, or visit the NWS website, weather.gov/hfo.
