Oahu was drenched with two bursts of rainfall over a four-hour period overnight, triggering a traffic nightmare and exposing a flaw in a drainage valve in Mapunapuna. The rainfall totals were impressive including a whopping four inches in Nuuanu in one hour. The first deluge hit at 10 o'clock Monday night.
"It hit pretty hard and that set the stage by saturating the ground," said Kevin Kodama of the National Weather Service.
Setting the stage for the second BURST at 2:30.
"We had 15 minute accumulations of 3/4 to an inch at 15 minutes," said Kodama. "You're talking about 4 inches in an hour rates in that short period of time, that's a lot of rain you don't see that everyday and so that will create quite a bit of runoff."
That was in Nuuanu where rain runoff roared over School Street.
"Apparently there was so much rain water that came down and it just kind of inundated the area and it didn't have anywhere to go and it overflowed over the curb which is really something that's never happened before," said Dan Meisenzahl of the State Transportation Department.
All ewa bound lanes of the H-1 Freeway were shut down at 3:20 after tons of mud washed across the freeway near the School Street on-ramp. Traffic backed up for miles as the Honolulu Fire Department and state crews worked for four hours clearing mud.
"We appreciate everyone's patience we know anybody who got stuck in that traffic it was a total nightmare today," said Meisenzahl.
Earlier in the morning, police had shut-down several lanes on the H-1 near Punahou Street for more than an hour because of heavy ponding.
"It's kind of a low point so we a pump there to help get the water out of there, there was so much water that the pump couldn't handle it," said Meisenzahl. "And so we had to get our crews down there, we had to get our own pumping system down there, fortunately we got that cleared before rush hour really began in earnest."
The nightmare ended at 7:20 when all lanes were reopened. Flooding was also a problem in Mapunapuna.
"How many cars have you seen stuck this morning? Three," said Joshua Sazer of Medallion Carpets on Ahua Street.
The area was notorious for flooding during high tides when sea water backed up through storm drains. The issue was magnified following heavy rains. But area businesses thought they would see relief after two large storm drain valves were installed several months ago.
"I thought they fixed that problem for this drainage," said Benny Carlos of Benny's Auto Body.
The seven inches of rain that pounded Moanalua in a 24-hour period revealed the valve is not functioning properly.
"It's keeping the high-tide water from coming into flood like this but then it only goes one direction so all the rain water that's flowing on this side can't go out into the ocean so it's stuck," said Sazer.
"That's what we thought too but I guess the valve opens for the tide but it doesn't open for the water yeah coming the other way," said Ken Kojima of Trans Quality. "
Many businesses closed their doors because flood waters would not subside even at low tide.
"You cannot make a living, you cannot even pay the rent if like this," said Carlos.
City officials returned to Mapunapuna and believe there is a blockage in one of the drainage valves. They hope to resolve this Wednesday.
