Flume ‘about 90 percent’ complete

The Waikamoi Flume should be fully operational by next month as the rotting and aging redwood of the flume is being replaced with shiny new aluminum that will improve the reliability of the system and may increase water intake for Upcountry, county officials said.

“The flume is beautiful,” said Maui County Water Director David Taylor. “About 90 percent of the flume is complete.”

The construction, which began more than a year ago, has gone well. However, stormy weather caused a need for roadway access repairs that stalled parts of the project, but nothing on the actual flume, Taylor said. While the flume will be fully operational in November, other work such as site restoration, which will not impact water collection or transmission, will be ongoing until March, Taylor said.

The flume, built on the ridges and in the valleys above Haiku more than 70 years ago, is one of several water collection systems that feed into the Olinda Treatment Plant, which supplies water to customers in Kula, Keokea and Ulupalakua.

The cost of the project is around $11.2 million for the 1.1-mile-long flume. Over the years, the flume has degraded with an estimated 40 percent of water during peak flows being lost through cracks and holes along the timber box. The aging system also has posed hazards for maintenance personnel who walk the flume, according to water department reports.

“The new flume will provide a more reliable transmission for water into our reservoirs for treatment at the Olinda Water Treatment Facility. This, of course, will provide a more reliable source for our Upcountry customers, farmers and nonfarmers alike,” Taylor said. “Because we do not have any way to calculate exactly how much water was lost, we are unable to quantify exactly how much more water we expect to have on an annual basis.”

But Taylor added that the additional water could be used to serve additional customers or to increase reliability to existing customers or a combination of the two.

The department will need to monitor the reservoir levels through a couple of seasons to get a better understanding of how much water to expect on a seasonal/annual basis, Taylor said.

The flume’s existing redwood structure is being replaced with aluminum in the same size and shape. The work, being done by Global Specialty Inc., started from the outlet of the flume and is going toward the intake.

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

Portions of the redwood flume were demolished and, wherever possible, workers installed piping to direct water around the work area to keep it flowing.

In some areas, a bypass was not constructed. Taylor said some of those instances included situations when reservoirs were full or when there was little water to catch due to dry weather.

The aluminum parts were put together at a warehouse facility in Washington state and shipped to Maui.

East Maui Irrigation Co. and Maui County manage the flume system that spans three stream systems – Haipuaena, Puohokamoa and Waikamoi. The system has 14 major gulch crossings, ranging from 8 to 31 feet high. The old flume supports were made of redwood but have been replaced by aluminum.

When crossing gulches, Taylor said, workers built supports and then constructed the flume across the gulch.

The flume sits at an elevation of 4,050 to 4,300 feet and is located within dense wet forest of ohia and native ferns and mosses. Hawaiians referred to this region as Wao Akua, a remote mountain area roamed only by spirits and thus not generally inhabited, according to the county.

The rainfall in the area averages 250 inches per year.

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 County of Maui Territorial Government built the current wooden flume.

According to the county, the last major work on the wooden flume was done in 1974 and 1975.

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