HONOLULU (HawaiiNewsNow) - It's hidden deep under several miles of Dillingham Boulevard: A water main big enough to provide water for Honolulu, Waikiki and Hawaii Kai.
Installation of the 42-inch main was finished about 11 years ago, after 10 years of work that involved tearing up the street.
Now, crews might have to dig up the main again.
The Honolulu Board of Water Supply will have to move parts, if not large segments, of the main to make way for the $6.5 billion rail transit project, Hawaii News Now has learned.
That came as a surprise to the newly-elected chair of the Honolulu Authority for Rapid Transportation.
"I had not heard before about a 42-inch water main. There is no way to avoid a 42-inch water main," said Chairwoman Colleen Hanabusa.
She added that she's concerned about how the dig might impact traffic and disrupt area businesses. The water main runs the length of Dillingham, from Middle Street to Liliha Street, right alongside the rail line.
"It's already a congested area so when ever you do any kind of major kind of construction, it will result in not only in inconvenience to the people in the area but also the small businesses around there," Hanabusa said. "We are not going to be very popular down there."
Hawaii News Now asked HART about the potential problem two days ago, but CEO Dan Grabauskas declined comment, saying his staff hasn't briefed him yet.
News of the main, which could add millions of dollars to the rail transit project's budget, is once again raising questions about HART's transparency.
Honolulu Mayor Kirk Caldwell said HART should be more open about potentially costly obstacles, like utility lines and water pipes.
HART officials only recently disclosed potential problems with electric utility lines in the same area. Placing those overhead electricity lines underground will increase costs by $70 million.
"We all know that in the largest construction project in the history of this place through the dense urban core, there are a lot of unknowns," Caldwell said.
"I know now that we're going to hit those kinds of things, those unknowns. But I think they need to be planned for a little better and explained to the public that it's not perfect, that we may have these unknowns that we're going to have to pay more (for)."
There are no cost estimates yet on how much it will cost to move the 42-inch water main. But some fear that the fixes could cost millions. Environmental activist Carroll Cox, who first uncovered the problem, said doing nothing about pipeline also could be costly.
"When the water main breaks, water is being released and it undermines the ground. Does that pose a risk to the structure of the rail itself?" he asked. "How do you service that main or breakage?"
According to the Board of Water Supply, all of the costs of moving the water main will be paid for by the rail authority-- and that both sides are still discussing how to proceed.