Search For Water in Saddle Region Begins

A $6 million drilling project with a dual purpose is underway in the saddle between Mauna Kea and Mauna Loa.

When the test well is complete, the US Army hopes to have discovered a source of water that could be developed for use by the Pohakuloa Training Area as well as lessees on Hawaiian homelands.

It is also hoped to quench scientists’ thirst for knowledge about the geology and hydrology of the saddle area.

Water is a scarce commodity in the saddle, forcing the Army to truck water up to PTA.

Most water wells tap water at the basal lens, a layer of fresh water that lies just above sea level.

However, University of Hawaii geologist Donald Thomas, who is overseeing the project, hopes that water will be found as high as 3,500 feet above sea level.

Such underground reservoirs are referred to as “perched” water, trapped above a layer of ash or bound by intrusive volcanic formations known as dikes.

But even if water is found at higher elevations, the plan is to continue drilling 6,400 feet down to sea level  to learn as much as possible about what lies below.

“What we’re trying to do is more than find the water,” Thomas said, adding that scientists want to find out why the water is where it’s at.

Thomas is definitely the right person for the project, having previously overseen the drilling of two research wells, including one near Hilo’s airport that was 11,500 feet deep.

The current project has reached a depth of 1,300 feet and has already encountered surprises as well as difficulties, he said.

“The geology was much different than we expected,” Thomas said.

He said almost immediately the well punched through about 100 feet of alluvial deposits, a mixture of sand, gravel and other materials left by glacial action on Mauna Kea from a past Ice Age. The deposit was several times thicker than anticipated, he said.

The well has also gone through a cinder cone buried under subsequent lava flows, indicating they may be drilling through an old rift zone.

But it has also encountered a great deal of broken rock which makes the drilling much more difficult, Thomas said.

Because the rubble tends to grab onto the drill bit and pipe, drillers are forced to pull the drill line upwards, allowing the rubble to fall into the hole before the drilling resumes.

Otherwise, the crew risks having the drill line becoming seized, which would force them to start all over again.

If the 4-inch test well is successful, it could pave the way for a much larger production well.

That would be very good news, said Leimana Damate, Hawaiian Homes commissioner for West Hawaii.

“The main problem is our inability to access water,” Damate said. “We’re excited about this test well’s research for possible water in the Humuula area.”

She said the Department of Hawaiian Homelands would be interested in establishing a production well if financing could be secured.

And the Army has long been interested in a new water source, especially since springs it previously relied upon dried up years ago.

“The potential benefit for the Army is that we would no longer have to truck water up to PTA on a daily basis, which is expensive and time-consuming,” said Lt. Col. Eric Shwedo, PTA’s commander.

“If we’re successful,” Shwedo added, “this test can have an overarching importance on the Saddle region.”

The PTA test well is an initiative between the Army’s Corps of Engineers and the Cooperative Ecosystems Study Unit, a national consortium of federal agencies, state and local governments, tribes and academic institutions.

The well is expected to take up to four months to complete. Thomas said if sufficient funding remains, a second test well will be drilled.