The water is flowing again in Waikamoi flume project

The $11.2 million Waikamoi flume replacement project has been completed, with the flume in full operation for the past couple of months.

Department of Water Supply Director Dave Taylor said the flume has been “working well,” and “no leaks” have been detected.

Work on the former wooden flume last year consisted of replacing wooden parts with aluminum ones. The old flume’s redwood planks had aged and degraded. An estimated 40 percent of water during peak flows was being lost through cracks and holes along the timber box.

An official blessing of the completed 1.1-mile flume on the ridges and in the valleys above Haiku was held May 30.

At the blessing Deputy Water Director Paul Meyer said the flume is in a “sensitive area,” a native forest.

“The reason we are able to receive water and use it as a drinking water source is that it is pristine,” he said. “The reason that it stays this way over thousands of years is because access, invasive species and foreign plants and animals are controlled.”

Meyer thanked all the workers involved, including Global Specialty Construction, which did the construction work while taking extra care and following strict protocols in the watershed.

The project area, called Wao Akua, was accessible in ancient days only by trained professionals because the watershed was essential to the health of people, Meyer said, quoting the project’s environmental assessment.

“The project site is located within Wao Akua, which is in the realm of the gods in ancient Hawaii,” he said.

With the reconstructed flume now in full operation, Taylor said that the department will continue to monitor Upcountry reservoir levels and total volume of water processed at the Olinda water treatment plant.

Water from the flume goes to the Kahakapao reservoirs and then the Olinda plant before treated drinking water is sent to upper Kula customers, Taylor said. The flume is one of several water collection systems that feed into the Olinda plant.

“By comparing future values to past values, we hope to gain some understanding of how much more water is being captured,” Taylor said of the new flume. “This will only be an estimate as precipitation is not constant and there were no direct measurements of past leakage.”

Taylor has said that the additional water could be used to serve additional customers and/or increase reliability to existing customers.

In addition to being leaky, the deteriorated water collection system was hazardous for water department personnel who maintained the flume. East Maui Irrigation Co. and Maui County manage the flume system.

No modifications were done to the system’s water intakes because an increase in the intake of water would have triggered other regulations and required additional approvals, the county said.

According to the county, the original Waikamoi water collection system was developed in 1908. The flume was first replaced and upgraded in the mid-1930s, when the wooden flume was installed.

According to the county, the last major work on the wooden flume was done in 1974 and 1975. It appeared at that time that water was leaking from the aging structure.

Retired agricultural and civil engineer William “Bill” Pyle of Pukalani remembered working with East Maui Irrigation Co. on replacing the flume 40 years ago.

“We brought in the best clear, heartwood redwood we could find,” he said, adding the overhaul was major project, just like this most recent one.

* Melissa Tanji can be reached at mtanji@mauinews.com.


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