A dike repair project in the Wailuku River aimed at protecting the town of Wailuku from future flooding and preventing further erosion is expected to continue in the spring after the county released a finding of no significant impact for the plans. of the project.
After years of repeated flooding and undermining of infrastructure in the river, the Iao Creek Embankment 27 Repair Project proposes to repair a 240-foot-long section of the riverbank, located downstream of the Imi Street Bridge. Kala and upstream of the dike 27.
“The proposed action will prevent further erosion of the bank, protect the downstream dike and reduce the risk of flooding in Wailuku”, according to the final environmental assessment published earlier this month in the Office of Environmental Quality Control “The environmental notice”.
The plan provides for the removal of an existing concrete block infill slope and the leveling of the slope; excavation to deepen the protection along the foot of the slope to be below the scour depth; and the construction of a new coating system consisting of a reinforced soil slope, poured riprap on the facade, the use of drainage pipes and the placement of dumped riprap at the foot of the slope to protect against scour, which can cause erosion.
The project area covers approximately 1.39 acres and is not part of the Iao Stream Levee system.
The estimated repair costs in the project area are $ 1.8 million, with construction scheduled to begin in the spring at the end of the rainy season and is expected to take between six and eight months.
Exact construction dates will be available once a contractor has been selected for the project, based on the environmental assessment. Dates are subject to change depending on permits, design and work schedule during the dry season.
From an upstream sediment basin to Kahului Bay, the Wailuku River is approximately 12,000 feet long and is located in the Na Wai ‘Eha watershed.
Over the years, projects have sought to stabilize the river and protect against flooding. The Iao Creek Flood Control Project, which dates back to the 1980s, was implemented to reduce flood damage to the town of Wailuku. The completed project includes a debris pond, canal improvements, a waterfall structure, dikes along the right bank, management of the floodplain along the left bank, and realignment of the stream with channel improvements.
Still, intermittent heavy rains have caused minor to severe flooding in central Maui and erosion of shoreline walls for the past 40 years despite emergency repairs.
According to the environmental assessment, the Wailuku River in the project site area is “In danger of becoming a flood zone again due to the erosion / deterioration / scouring of the right bank and the weakening of the foot of the bank”.
In order to “Preserve the reliability of the bank”, protect the downstream dike and reduce the risk of flooding for the community of Wailuku, the county public works department said repairs are needed.
“In the long term, the proposed action is expected to have beneficial environmental and social impacts as it will prevent further erosion of the bank, protect the Iao Stream 27 dyke downstream and reduce the risk of flooding for the city of Wailuku caused by design flaws. and long-term damage to the existing bank stabilization structure suffered during repeated flooding since its original construction and subsequent repairs ”, according to the environmental assessment.
* Dakota Grossman can be contacted at [email protected]