Mapunapuna streets are finally dry at high tide, and business people in the industrial district say they are grateful for drainage modifications that appear to have cured decades of tidal flooding.

Patricia Sullivan, vice president of Mr. Sandman Inc., a sandblasting company along once-flooded Ahua Street, said the area has not experienced flooding since a contractor for the city completed the project in late July.

"It’s really wonderful," Sullivan said.

Mapunapuna is filled-in former marshland that over the years has sunken below the high-tide level in spots. For years, seawater would flow inland through drainage pipes at high tide, flooding some streets and businesses.

To fix that, the city hired Eckard Brandes Inc. of Kailua to install two "duckbill" valves in the drainage system that allow rain water to drain to sea but keep seawater from flowing the other direction.

Eckard Brandes installed the valves July 27 and July 30. The company is still in the process of permanently plugging a drainage pipe that runs from Moanalua Stream to Ahua Street, as the stream is considered another source of flooding. The total contract is for $865,900.

Patricia Middleton of Volcano Orchids and Funeral Wreath Shop on Awaawaloa Street said the best part of the improvements is that her customers and people passing through Mapunapuna no longer have to drive through pools of salty water, which can be at deep as 2 feet.

Middleton and other business owners said the true test of the improvements will be during a heavy rain at high tide, when water will be trying to flow makai and mauka in the drainage system.

Jeff Iwasaki-Higbee, president of Eckard Brandes, said that in such a situation, the rain water won’t be able to drain effectively.

However a rain during normal conditions, "should not be a problem at all," he said.

Cathy Daney, store manager of Hardware Hawaii on Mapunapuna Street, said the streets dried up right after the valves were installed.

"The change was immediate," she said.

Besides the potential of flooding damaging the store’s stock of lumber, flooding left pools of water that created a breeding environment for mosquitoes, Daney said. The presence of mosquitoes has been drastically reduced, she said.

Iwasaki-Higbee said at high tide small pools of water have been collecting at the catch basins at Ahua and Mapunapuna streets, which collect about a foot away from the sidewalks. The cause, which could be due to debris buildup or leaky pipes, still needs to be determined.

Most of all, Middleton said she is grateful that the engineering solution worked to keep the streets dry for the most part.

"I’m so pleased that on the first try they have done something and been successful, which in turn pleases all the taxpayers," she said. "This is definitely an improvement."