Work on long-awaited Lahaina flood control system to begin
LAHAINA — Officials discussed plans for the proposed Lahaina Watershed Flood Control Project — a system of waterways to intercept and divert floodwater above Lahaina Town — at a meeting last week Wednesday at Lahaina Civic Center.
Groundbreaking is expected within the next six weeks for the long-awaited project, which will provide flood protection to the area between Lahainaluna Road and the community of Puamana.
The speakers were Wes Nohara of the West Maui Soil and Water Conservation District, Joe Krueger from the county Department of Public Works and Dudley Kubo from the U.S. Department of Agriculture’s Natural Resources Conservation Service.
Nohara shared the history of the flood control project, which began in 1960 when the Lahaina community suffered a major flooding event.
The Army Corps of Engineers began the Kahoma Flood Control Project in 1970 in the northern portion of Lahaina Town and completed it in 1990.
Two years later, the flood control project plan and Environmental Assessment (EA) were completed.
In 1993, the project was authorized by the Natural Resources Conservation Service, but construction was halted due to a lack of funding and the need for the state to review the EA.
When severe flooding occurred in Lahaina Town in 1996 and 2001, implementation of the Lahaina Watershed Flood Control Project became a priority.
An Environmental Impact Statement for the system was completed in 2004, followed by a design for phase one and construction contract in 2006.
According to Kubo, the channel will be built in five phases and is expected to take 5-7 years to complete.
Expected to be done by 2011, phase one will begin in late October with the construction of an outlet structure, highway culvert and sediment basin at Waianukole near Launiupoko by contractor Kiewit Pacific Co. Total cost for Phase I is $6.26 million.
Runoff will be monitored during construction to protect the reef and nearshore environment.
As described in the EIS, the two-mile flood control channel will extend from Lahainaluna Road to Waianukole, two-thirds-of-a-mile south of Puamana Park. About 10,000 feet of the proposed channel will be grass-lined.
The remainder of the channel system will include four sediment basins, one debris basin on Kauaula Stream and one inlet basin near Lahainaluna Road.
One ocean outlet will be at Makila Point through Kauaula Stream and the other at a new outlet at Waianukole. Both ocean outlets will have sediment basins to reduce flood debris that enter the ocean.
The county will be responsible for all maintenance.
Kubo stated that the project encompasses 5,250 acres of the Lahaina Watershed. When it rains heavily, the south end of town is at risk for flooding.
Based on the EIS, the channel is expected to keep 1,200 tons of sediment and debris out of the ocean and protect against floods at the “100-year” level. According to the U.S. Geological Survey, the term “100-year flood” means that there is a one-in-100 chance that a powerful storm will hit and cause damaging flooding.
Hans Michel of Lahaina asked if there is money to complete the entire project. Krueger responded that the partners have the total sum of $6.26 million for phase one. The cost is shared equally between the federal and Maui County governments. Additional money will be appropriated as the remaining four phases become shovel-ready.
Krueger explained that phases two and three will continue along the mauka side of Honoapiilani Highway at the existing Puamana Channel. Phase two will consist of a grass-lined diversion that will be parallel to the highway at Launiupoko. A large sediment basin will be built during phase three to collect stones and boulders that tumble down from Kauaula Stream during the rainy season.
Krueger stated that phases 1-3 are designed so that traffic along the highway can travel at 45 mph. “The only slow down will be people rubbernecking to get a look at the project,” he said.
Phase four will continue from the Kauaula Stream westward to the former Wainee Villages site, where hundreds of people lived in the early 1900s. Howard Hanzawa, vice president of Kaanapali Land Management Corp. (KLM), commented that it will take three to four years to complete phases 1-4 of the flood control project.
KLM is waiting for the completion of the flood control project, so the company can move forward on its Wainee Villages project.
Phase five will start above Dickenson Street and end at Lahainaluna Road about 153 feet above Honoapiilani Highway. This final section will include an inlet basin, reinforced concrete channel and sediment basin.
Pat Sullivan stated that he came to the meeting because the property he owns on Wainee Street near Waiola Church gets flooded. Krueger explained that it will take about five years before Sullivan will see a reduction of flooding.
Kauaula Valley resident Ke‘eaumoku Kapu expressed concerns that the project is in Historic District One. Kapu and his family live above the historic area and want to be sure that all Hawaiian artifacts are protected.
Krueger informed Kapu that archeological monitoring will occur during all phases of construction.
Kapu added that the county has promised to build a cement bridge over the flood control channel to preserve roadway access to their property.