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Branden 06-24-2010 06:53 AM

Sump Pump
 
I have a driveway sloping towards the house. I replaced the drain there with a long trench drain and new concrete. The trench drains into a sump pit and is pumped back out of the side of the house into a downspout.

During some really heavy storms yesterday, the pit was filling up to where the pump was switching on frequently, I'd guess about once every 30-45 seconds. I got the pump for free and it works great, but if the power would of went out I would have been really screwed.

Can anyone make a good suggestion on a sump pump w/ battery backup? Also, what specs should I be looking at when purchasing one. Would like to purchase ASAP to prevent a disaster area in my garage.

Scuba_Dave 06-24-2010 11:48 AM

Is this all outside of the house ?
No chance to daylight the drain instead of using the sump ?

Branden 06-24-2010 11:55 AM

1 Attachment(s)
No, it's inside the house. The driveway slopes towards the house. Put in a drain at the bottom of the driveway and it drains into the sump pit which is right inside the garage doors over to the side. Once the pit gets high enough to activate the float, the water is pumped through a 2" pipe up about 6 feet total and then 90s out through the wall of the garage and over to a downspout.

I was thinking about adding this in case I lose power. Not too sure how to size these pumps though.

Dave, when I say 'trench drain' I am not talking about a buried drain, see the long drain I installed in the pic below.

http://www.lowes.com/pd_117257-84862-BWEL_4294820779_4294937087?productId=1213355&Ns=p_ product_price|1&pl=1&currentURL=/pl_Pumps%2B_4294820779_4294937087_?rpp=15$No=0$Ns= p_product_price|1

or

http://www.lowes.com/pd_117160-84862-BWSL_4294820779_4294937087?productId=1213351&Ns=p_ product_price|1&pl=1&currentURL=/pl_Pumps%2B_4294820779_4294937087_?rpp=15$No=15$Ns =p_product_price|1

The Engineer 06-24-2010 12:57 PM

Your driveway footprint draining to the sump basin is around 1000 square feet, right? If so, you would see 10 gpm under a 1" per hour storm, 20 gpm under a 2" per hour storm and so on. The pump you linked to looks like it can only handle 16-17 gpm discharge rate, so if the storm is any more severe than a 1.5" per hour storm, the pump will not keep up.

Just wanted to add, that in my state, I have to design all my ejector pumps for a 4" per hour rain storm.

Branden 06-24-2010 01:17 PM

Yeah, I'd say 1000 sq ft. is a close estimate.

For the smaller pump (first link) the discharge is rated at 1000 GPH @ 10' rise and 2000 GPH at no rise. I am at about a 6' rise, so I am looking at getting 1400 GPH out of it. That works out to be about 23 GPM which would handle 2" in an hour, which is a lot of rain in an hour.

It might be a better idea to go with the pump in the 2nd link just to be safe. It'll handle about 33 GPM in my situation. I'm not sure if I want to spend an extra $104 on something that will rarely be used and might go with the first one. Maybe I'll do some research on average rain per hour in Pittsburgh

Anyway, thanks Dave and Engr.

Branden 06-29-2010 09:33 AM

Engineer,

4" per hour? That seems a little intense. Does that include a battery backup pump like I am looking for? I don't doubt that my main pump could handle that, but I don't even think I can find a battery backup that could handle that much rain.

The Engineer 06-29-2010 03:41 PM

Quote:

Originally Posted by Branden (Post 462866)
Engineer,

4" per hour? That seems a little intense. Does that include a battery backup pump like I am looking for? I don't doubt that my main pump could handle that, but I don't even think I can find a battery backup that could handle that much rain.


Hi Branden, remember that 4" per hour is the "rainfall rate", it doesn't necessarily mean 4" of rain will fall in 1 hour, it could mean a 15 min. passing thunderstorm drops 1" of rain, it could mean a 7-1/2 minute downpour could drop 1/2" of rain. Even though a short duration storm drops a ton of water in only a few minutes, it could still be a 4" per hour rainfall rate storm, which in my state is what the code says we have to design our piping and pumps for. I deal mostly with commercial buildings and multi-unit residential buildings, so we put all our storm pumps on emergency generators, so I don't deal with battery backup pumps at all. The only advice I can give you, is to get the largest pump you can get with a battery backup. I think the 33 gpm pump you mention will be fine for 99% of the time.


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