dewatering pump design

[captvt]

I hope someone can lead me in the right direction. I am trying to size and configure a pumping system that will dewater a basement mechanical room in the event of a storm surge caused by a hurricane event. This project is on an island off the coast of Massachusetts and involves a 1200 sf basement, the bottom of which is at normal groundwater level. I don't understand the mechanics of storm surge and the rate of inflow I would be faced with during an event. Ground level is 14' above sea level and the basement floor is 5' above sea level. I have a 24" diameter by 3' deep perforated sump in the floor. An electric pump is preferable so it can be tied into the emergency power. Help!

 

[Artisi]

before we can give any help we need some indication of inflow - and seems only you can provide this information.

Naresuan University
Phitsanulok
Thailand

 

[MikeHalloran]

In a storm surge, the sea rises, and flows up the street to your house. The inflow rate will be determined by how high the water reaches above the basement windows, and the area of the window openings. The water pressure will automatically remove the glazing from the windows, so no worries there. You have zero hope of pumping it out as fast as it comes in.

After the ocean recedes, and you have cleared the wreckage of your neighbors' houses from around your own, you might wish to dewater the basement, which will be ... full of water. I hope you bought a fully submersible electric pump and that your emergency power source survives the storm.

Oh. The water will be full of trash, so a centrifugal pump will clog every few minutes, and you will have to haul it out, disassemble it, clean it, reassemble it, and drop it in again, and repeat ad nauseam.

Given all that, you might wish to instead invest in an engine powered diaphragm style dewatering pump. You leave it outside, snake the semirigid suction hose into the basement, start 'er up and keep adding fuel until she's burped out the contents of the basement onto your lawn.

When the water level gets low enough, you can put the pump in the basement on a makeshift raft to reduce the suction head while it gets the last few thousand gallons out. You won't be living in the house, and the basement windows are gone, so ventilation of the exhaust is not a big problem.

;-)



Mike Halloran
Pembroke Pines, FL, USA

 

[cvg]

better than pumping, you should consider flood proofing. you can find plenty of information on both storm surge and flood proofing on the FEMA website, or try the Assoc of State Floodplain Engineers site

http://www.floods.org/home/default.asp

 

[JohnNabors]

Captvt-

One product line made by the company I work for consists of hydraulically driven submersible pumps powered by hydraulic power units driven either an electric motor or by a diesel engine. I can't get to the specs right this moment due to a network issue (which is why I'm fooling around in here at the moment), but I belive the maximum flow on the largest model we make is around 8000 gpm with a shutoff head of about 100'. Since the pump would rarely (hopefully for your sake never!) actually pump seawater, using something like brass or monel for the volute, impeller, etc. would be unecessary. The parts exposed to flowing seawater could be cast iron treated by a salt bath nitring process or with a Xylan coating that would impart sufficient wear resistance for a short run (just run some fresh water through it after everything quits blowing all over the place) and enough corrosion resistance for long term exposure to salt air.