State Plans to Raise Highway 11 in Ka`u

The state is looking to raise a section of Highway 11 in Ka`u that has been the location of persistent flooding over the years.

The Department of Transportation is proposing to raise a 3,700-foot section of the highway at Kawa Flats.

The roadway would be raised 10 feet, which would leave it about two feet above the 50-year flood level.

The project would include construction of a reinforced concrete box culvert to allow flood waters to pass under the highway.

The culvert would consist of six cells, each 12 feet long and eight feet high.

According to an environmental assessment prepared for the project, the highway was built more than 50 years ago without any drainage system for the low-lying section.

Source: Mamalahoa Highway Drainage Improvements at Kawa Flats EA.

The EA said the highway, which is the only route connecting Ka`u with Volcano — other than a 15-mile detour on old plantation roads — has been closed by flooding at least six times since 2002.

A two-lane bypass road would be built mauka of the highway during the project’s construction phase.

When completed, an intersection near the northern end of the project would provide access to the shoreline property at Kawa recently acquired by the county as part of its “Open Space” program.

The DOT is asking the state Board of Land and Natural Resources to grant a conservation district use permit for the project.

The land board is scheduled to take up the request at a meeting Friday in Honolulu.