Crews from the Hawaiʻi Department of Transportation, City and County of Honolulu Department of Facility Maintenance and Goodfellow Bros. Inc. started flood mitigation activities Monday, Aug. 3, at Mānoa Stream to reduce flooding risks.
"The flood mitigation project in Mānoa Stream is designed to restore the stream's capacity to convey stormwater more effectively and address community concerns about flooding,” a DFM spokesperson told Aloha State Daily by email Tuesday. “The work includes removing vegetation, debris, accumulated silt, and sediment, as well as regrading the stream slopes and reestablishing the channel bottom to improve water flow.”
The project will not expand or alter the existing walls.
Phase one of the project kicked off this week between Kahaloa Drive and the Woodlawn Bridge. Construction activities will take place from 7 a.m. to 5 p.m. The first phase of the project is expected to take approximately two months.
The Mānoa Valley District Park dog park pathway closed Monday for the stream cleaning. The main circular dog park area will remain open and accessible through the Lowrey Avenue parking lot. A portion of the Kahaloa Drive parking lot will be closed during the first phase of construction. The Department of Facility Maintenance does not currently anticipate lane closures in Mānoa.
The second phase will focus on the section between the U.S. Department of Agriculture fruit fly laboratory and University of Hawaiʻi at Mānoa Housing Apartments to the Woodlawn Drive bridge, and the third phase will start at the Woodlawn Drive bridge and work upstream toward the McDonald’s area between mid-October and early December.
Any work to remove trees required for the project will be scheduled after the ʻōpeʻapeʻa (Hawaiian hoary bat) pupping season ends in mid-September to minimize impacts to protected wildlife.
A $1.7 million allocation from the state’s Major Disaster Fund backed the stream mitigation work. DFM will fund the transportation and disposal of debris removed from the stream.
According to U.S. Geological Survey data, a National Weather Service stream gauge at Woodlawn Drive measured that the stream jumped to 15.79 feet at 1:45 p.m. on March 23 after the second Kona low storms dumped 3 ½ to 6 ½ inches of rain in the Nuʻuanu-Mānoa area. Above average rain and the back to back Kona low storms made it the wettest wet season in the last 30 years.
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Haley Lehman can be reached at haley@alohastatedaily.com.
