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Hanalei Riverbank Restoration. High Tides, Hau Bush and Habitat

Eric Seidl, LEED-AP
Envirolok
Sun Prairie, WI

The Hanalei River is an active recreation river that spans nearly 16 miles through the northern half of the island of Kauai, Hawaii. The base of the river begins along the slopes of Mt. Waialeale, where it is engulfed by 450 inches of rain per year and eventually drains its 23-square-mile watershed into the Pacific Ocean at Hanalei Bay.

With frequent rains and tropical storms, the banks of the Hanalei River are no stranger to erosion. In 2016, design and permitting of a bio-engineered solution for 450’ of riverbank restoration at a resort and retail site began. As the design team finalized the design and neared the issuing of permits in 2018, a tropical storm dumped over 40” of rain in less than 48 hours, eroding the bank to less than 5’ from the footings of the cottages and other infrastructure. With the loss of additional infrastructure and flooding of buildings, the riverbank project was put on hold. Fast forward to 2022, the cottages and retail site were purchased by a new owner. Design work resumed based on new site conditions and client needs. Permits were revisited and construction was ready to begin in late spring of 2023.

Access to updated site information left many questions to be answered and required a design-build approach. Working in a tidal environment with frequent daily rains made for a limited construction window. Delays in permitting and erosive spring storms required temporary repair to limit further bank failure.

This presentation will dive into the challenges of design and construction of toe protection as well as the bio-engineered system along the upper banks. Learn about how the design and construction team worked together on-site to overcome the challenges and provide a long-term solution that would meet the constraints of the permit, project budget, and client expectations.



About Eric Seidl
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