South Florida is a patchwork of hundreds of miles of flood control and drainage canals. If they become clogged with debris, water has nowhere to go.
The South Florida Water Management District, counties, municipalities and homeowners’ associations spend millions a year to maintain drainage systems in our neighborhoods. Nothing can guarantee against flooding during a heavy rain. But if debris clogs canals or flood control structures such as locks or grates, that can cause a “domino effect” that can back up the entire system.
If you see a debris blockage at the start of the season or during any heavy rain, don’t try to remove it yourself. Alert the responsible agency. If you see a blockage right before the storm, pull it out yourself if it’s practical and safe to do so.
If a storm is expected to drop heavy rains, the WMD will open floodgates to lower canal levels.
During and after the storm, street and yard drainage will be slow if previous heavy rains have saturated the ground and left canal and sewer levels high.
South Florida’s climate is notorious for its ‘locally heavy’ rainfall. Your relative on the other side of town might get almost no rain while you get a couple of inches.
Locally heavy rainfall might tax your neighborhood’s drainage system. But steady heavy rain across the region can back up the entire drainage network. Tropical Storm Fay, in August 2008, left up to 5 feet of standing water in parts of the Treasure Coast.
If a hurricane threatens the Lake Okeechobee area, experts have said they can’t guarantee the Herbert Hoover Dike will protect those living around it.
A 2006 report by engineering experts hired by the South Florida Water Management District said the dike has narrowly escaped failing from leaks and erosion in recent years. They estimated a 1-in-6 chance the dike would breach in any given year.
A dike failure would cause billions of dollars in damage, could irreversibly damage the Everglades, would threaten to contaminate South Florida’s water supply and “would submerge vast areas . . . to the south and east,” the report said.
In response, the U.S. Army Corps of Engineers has significantly revamped its rehabilitation plans for the dike — an effort now scheduled to be finished in 2022 at a cost of $1.8 billion. The corps has also reduced water levels in the lake to lessen the risk in the meantime.
HOMEOWNERS’ GROUPS SHOULD CHECK SYSTEMS
Your homeowners’ association, if responsible for a lake or drainage system, should hire a private firm at the start of each hurricane season to:
Find out the age, sophistication and condition of drainage systems in your area and which agency is responsible for them — and make sure that agency is being diligent.
Inspect the system, remove debris, flush out sediment, stabilize erosion and make repairs.
Regrade the swale, if necessary, to improve drainage and storage capacity.
Cut away vegetation that’s leaning down into canals or weak branches that might break and fall in.
Deepen ditches or canals. Note: The company you hire will need to check with government agencies first; a permit probably will be needed for this type of work.
Some homes vulnerable to flooding might benefit from sandbags. Make plans now. Procuring materials, and filling and placing sandbags is a laborious and time-consuming process.
Work in pairs with one person holding the bag while the other shovels the fill material.
Fill until the bag is approximately one-third to one-half full. A completely full bag of wet sand or soil will be too heavy to work with.
Lay plastic sheeting on the ground and up the building walls to a point at least 1 foot above the predicted water elevation, and far enough out on the ground to form a half pyramid of sandbags.
Place a solid row of sandbags on all edges of the plastic sheeting (half on the ground and half on the sheeting).
Fold over the empty top of the bag in a triangle to keep sand from leaking. Place each bag over the folded top of the preceding bag and stomp into place before placing next layer of bags.
Stagger the second layer of bags, stomping each bag into place before placing the next. Stomp each succeeding layer.
South Florida Water Management District: (561) 686-8800 or (800) 432-2045. www.sfwmd.gov