Miami Beach

‘King tide’ will be first test for Miami Beach’s new pumps

An energy disipator at 14th Street and West Avenue. The disipator is the last part of the water removal process that places water from street level into the bay, having gone through the pumping station which is underground. Monday, October 6, 2014.
An energy disipator at 14th Street and West Avenue. The disipator is the last part of the water removal process that places water from street level into the bay, having gone through the pumping station which is underground. Monday, October 6, 2014. MIAMI HERALD STAFF

The tides are rising this week in South Beach, and everyone’s watching to see whether newly installed pumps will control the flooding.

During this week’s king tide, city officials hope to avoid the familiar scenes of people wading in ankle-deep waters and cars splashing down Alton Road and West Avenue.

Officials are banking on their $15 million investment in stormwater pumps to mitigate this year’s highest high tides, which are expected to arrive Wednesday and Thursday, according to the National Weather Service. The projected high tides will be around 9 a.m. and 9 p.m. and are supposed to reach about 3½ feet both days. Areas on the west side of South Beach start to flood at around 3 feet.

Freshly installed pump stations are already working at 10th and 14th streets along West Avenue, as well as two updated pumps in Sunset Harbor. Temporary pumps at Fifth Street should also help stem the tide, and the city plans to build another permanent pump at Sixth and West within the next six months.

All of this, according to city engineer Bruce Mowry, is expected to minimize flooding — resulting in less standing water for shorter times.

He emphasized that these are short-term solutions when considering a larger and far-reaching issue of sea level rise. Since the westernmost swath of South Beach sits low, he said, the area will essentially be ground zero.

“This is the biggest area impacted by sea level rise,” he said.

The $15 million spent so far is the first fraction of the $500 million the city plans to spend during the next five years on 58 pumps up and down the Beach. The Florida Department of Transportation also plans to install pumps at 10th and 14th streets and Alton Road. The construction that has plagued Alton all year — expected to wrap up before the end of the year — has been to improve drainage.

The new pump systems are connected to the new drainage infrastructure under Alton, so conditions are expected to be better there, as well.

Public works director Eric Carpenter said that with the pump projects, the city is updating infrastructure that is at least 50 years old. City leaders hope they will provide relief for 30 to 40 years, but all agree the long-term strategy will have to include revamping the building code to construct buildings higher off the ground, making roads higher and constructing a taller seawall.

Mayor Philip Levine said the conversation would continue for years on how exactly to prepare the Beach for rising waters.

“We know the questions,” he said. “But don’t have all the answers.”

The tide is high

The king tide occurs when the sun and moon align in a such a way that their gravity tugs at earth’s water enough to create the highest of high tides.

In Miami Beach, the highest elevations run along the sandy beaches, and the lowest lands lie to the west, in areas that used to be mangroves. In a way, a natural event like the king tide simply sends this dense, built-out section of land back to the state Mother Nature intended it to be.

The king tide does not send water careening over the western seawall from Biscayne Bay, but it raises the tide high enough that it seeps into the drains underneath the city through Florida’s porous soil and limestone.

“It’s like water flowing through a bunch of marbles,” Mowry said.

The water then rises through the storm drains and, if there is enough of it, floods the streets. Before the current upgrades, faulty caps on the pipes where the water comes out led to either backed up drains behind jammed caps or water rushing back up into the drains because the caps were gone.

And rainfall always makes matters worse.

The new pumps are designed to collect the water, filter it and push it out to Biscayne Bay. Special valves prevent it from flowing back.

It might not sound logical to pump water back into the bay that is causing the flooding, but Mowry explained that the seepage is slower than the pumps, each of which can move about 14,000 gallons per minute. The water removed from the streets is not enough to raise the level of the bay any more than the king tide already has.

A key factor of the new pump system is the valve that prevents water from rushing back in through the release point.

“It’s like a trap door,” Levine said. “The water goes out one way, and it can’t come back.”

During this week’s king tide, the city estimates it will be able to pump about 50,000 gallons a minute, or the equivalent of three to four swimming pools. It could still take time to drain a flooded street, particularly if rainwater adds to the problem, but officials hope to see less standing water for a shorter amount of time this year.

“We’re hoping people don’t have to use sandbags this year,” he said.

If people do have problems, they are being encouraged to report any flooding they see to the city by calling 305-604-2489 or using the city’s mobile app, Miami Beach e-Gov.

Residents and politicians alike will have their eyes on the Beach this week to see whether the city’s early efforts relieve the problem.

Last week, U.S. Sen. Bill Nelson, D-Fla., announced that he was bringing a contingent of senators to South Florida on Thursday to see how the streets around Las Olas Boulevard in Fort Lauderdale flood during the king tide. He said he would not visit Alton Road, where he believes the street will be dry thanks to the new pumps.

“I think the pumps are going to be so effective that you won’t have the visual of the water sloshing around on Alton Road,” he told the Miami Herald after delivering a speech at Jungle Island.

Some local students are also watching closely.

During the king tide, students from Florida International University and MAST Academy will be out to collect data to study the flood waters and the quality of the filtered water being ejected into the bay. A balloon will capture images from 150 feet in the air to document the scene.

Miami Herald staff writer David Smiley contributed to this report. Follow @joeflech on Twitter.