If you protect a building with a floodwall, sealant, plastic wrap or any other barrier, you will need to pump water during floods.
Rainwater that falls inside the flood barrier or water that seeps under the barrier must be pumped to the outside. Water that comes in through leaks in the barrier or around gates and other closures also must be pumped out.
You can reduce seepage and leakage with careful design, construction and maintenance, but water will get in. The flood protection system you put in place should include an area (a sump) where water can collect and be pumped out before it causes damage.
Sump pumps sit in the sump. An electric, submersible sump pump will typically handle small debris and small water volumes (under 4,000 gallons per hour).
"Trash" or "utility" pumps usually sit above water level and draw through an inlet hose. Their specifications should include debris-handling ability. Typical pump capacity for these types is in the range of 10,000 gallons per hour.
The first rule in selecting a pump is “know what you want the pump to do.” Then your pump dealer can assist you in choosing a suitable pump.
Here are some other considerations
Design to Minimize Pumping Requirements
|Source of Water You Need to Pump||To Minimize Water From This Source|
|Rain inside the barrier
Two inches of rain on a 1,600-square-foot roof will produce 1,984 gallons of runoff.
|Place a flood barrier where rain on the roof can fall naturally to the water side of the barrier. |
Use gutters to collect roof runoff and channel it over the barrier.
|Water seeping under the flood barrier.||Use underground barriers to increase the distance water must travel to get under the barrier.|
|Water coming through cracks, leaky closures and inadequately blocked drain pipes||Use well-designed, tight-fitting panels instead of sandbags or loose plywood for closures. |
Maintain barriers and back-flow valves annually.
Estimate all the significant sources of water intrusion in terms of gallons per hour. If your barriers are in good condition, the seepage and leakage should be small. To determine the pumping capacity required to handle rainfall, calculate gallons per hour of rainfall this way:
Pumps may be used to fill water-inflatable barriers. You’d be interested in a high-volume pump; debris and head may or may not be a problem, depending on where you’re getting the water.