Sump pump not overflowing pit.....why?


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Old 03-13-14, 11:57 AM
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Sump pump not overflowing pit.....why?

Hi folks,

I have a submersible sump pump in my basement. The pit is dry most of the year, but when we get a major storm with massive amounts of rain, the pump kicks in to overdrive. By overdrive, I mean it will cycle on and drain the pit every 3 minutes for anywhere from 3 to 10 days straight.

My question though, isn't about the pump itself. During Hurricane Sandy, my pump chugged away every 3 minutes, pumping hundreds of gallons of water out of the pit. Late that night, our power went out. I got into bed, resigned to the fact that I was going to wake up to a destroyed, flooded basement. I was so upset about it that I couldn't even bring myself to go look in the basement at the time the power shut down. I layed in bed thinking about how the pump had been cycling 20 times per hour, and thinking about how many gallons of water that was.

To make a long story short, when I woke up the next morning and got up the guts to open the basement door.......I looked down at a bone dry floor. The power came on a few hours later, and the pump started cycling every 3 minutes again.

The question.........How did the sump pit not overflow?? A pump that was going off every 3 minutes did not run for nearly 15 hours and yet not a drop of water overflowed the sump pit. I know that the pump is actually emptying the pit during each cycle. I had been thinking about buying a backup battery system, but if the sump will not ever overflow, maybe I don't need one?

Any thoughts?

Thanks!!!!
 
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Old 03-13-14, 12:05 PM
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There is always a time lag with perforated drains/sump since the do not turn on or off immediately. It is not like a valve that turn water on or off like a faucet. Your pump worked satisfactorily, was able to run later and the water and pressure outside the basement there not high enough to get water into the sump. - It is good that the power went out when it did and not go out a few hours earlier.

Dick
 
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Old 03-13-14, 12:07 PM
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The water table in your area max's out before the threshold of your sump pit. You should raise the level of your pump, or raise the float if your pump has an adjustable one. If a hurricane can't overflow your pit during a power outage, then you should not be pumping for 10 days after any amount of rain. You're pumping out ground water that only dissipates after the level of your area's water table recedes.
 
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Old 03-13-14, 01:04 PM
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Thank you both for your replies!

Siuvinson, you mention the water table and Concretemasonry mentioned the height of the water pressure outside the basement. If I understand, is it something like "water finding its own level", meaning that if the water under the basement slab doesn't go higher than the level of the floor, I won't get a flood? I guess it's sort of like if you put a hole in the side of a plastic cup and push it into a sink of water, the water in the cup will only be as high as the level of the water the cup is standing in.

A little bit about my sump pit.....the guy who put it in drilled a bunch of holes in the basin and put it in the hole surrounded by rock. Water pours in from those holes after a massive rain, so as you say, I agree that we are pumping out ground water. When the pump cycles on, it will empty the pit, but the water pours back in immediately from those little holes. Is that wrong?

Thanks again!!
 
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Old 03-13-14, 01:09 PM
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You have a dry basement. Hooray!

Years ago, most people had them, then cow pasture land began being developed and wet basements became "normal."

My father wouldn't buy a house that had a sump pump in it because that meant it would flood someday, just like he won't buy a house that has an above ground septic drain field. If we went to look at a house and he saw either one of those things, he turned around and walked out.

A sump pit was fine, but a sump pump in the sump pit was a no-no.
 
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Old 03-13-14, 01:19 PM
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Trust me, Vey. My next house will NOT have a sump pump! LOL This basement has caused me so much stress worrying about water. Never again!
 
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Old 03-13-14, 02:59 PM
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JeffB777 -

That sump pump is probably saving you from having a wet basement.

Your pump is keeping the local water level below the floor from occasionally coming up into the basement (usually a day or two after a big storm. The holes were necessary to get the sump pit installed and provide a slow collection of water. - If you can somehow plug the holes, the water in the sump pit can eventually flood the basement if it overwhelms the pump's short term capacity.

That is the reason for a sump pit and drain tile in a poor home location. Next time, get a house on the top of a hill and pray that the surrounding soil is not a tight clay.

Dick
 
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Old 03-13-14, 04:51 PM
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This time the water table did not rise above basement floor level so in hindsight your sump pump did not need to turn on do any work. The water level would have come up and stopped at a certain level if the pump had not kept cycling.

But keep the sump pump in place ready to go in case next time the water table does rise above basement floor level.

Holes in the bottom of the pit liner make no difference regarding the water table. The holes may have an advantage in that, if the water table rises, you don't have the buoyancy of the empty pit liner that could result in the liner floating up, possibly deforming or cracking other components of the sump pump and drainage system.

But a disadvantage of the holes might be added dirt seeping up into the pit. If this happens, you may want to set the pump to shut off an inch or two before the pit is fully empty to avoid having the pump clog with dirt.
 
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Old 03-14-14, 06:46 AM
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[QUOTE]This time the water table did not rise above basement floor level so in hindsight your sump pump did not need to turn on do any work. The water level would have come up and stopped at a certain level if the pump had not kept cycling.[QUOTE]
AllanJ.....This is what I was thinking was the reason why I didn't get water flooding out of the sump pit after the power went off, but I wanted to be sure. So it seems that as long as the water table stays below the level of the concrete floor, I won't have water coming up and out of the sump pit, even if the pump stops running. If that's true, than I most likely don't need to worry about a backup battery system or backup sump pump.

Concretemasonry......Believe it or not, my house is actually up on a hill (not at the top of the hill though). People in the area do say that there is a high water table, even though we are on the hill. My backyard is flat and my front yard slopes down away from the house, so I'm not sure why I have water issues sometimes.

Thank you all for your assistance!!
 
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Old 03-14-14, 03:24 PM
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Note: The water table can be noticeably higher on one side of your lot compared with on the other side. This is in addition to rising and falling depending on rainfall on your lot and on neighboring lots.
 
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Old 03-15-14, 05:32 AM
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2cents here:

Is it possible that your discharge pipe from the sump pump is not dumping the collected water far enough away from the foundation ? So that when your pump IS continuously cycling on, it is recycling over and over the same water??

Also. Has it been determined whether or not there is any weeping tile (drainage pipe) that feeds into the sump pit, or is it just poked holes in the pit itself?

I ask because if the pit fills to a certain level (higher then what the float is set to) and then drains, it
could be possible that there is a drainage pipe that daylights far away. ( like mine, The previous owner didn't tell me about it and it had closed over with earth and grass. An investigation on a soggy spot lead to its discovery. Unclogged, and now the pump (which is set higher then that hole) rarely cycles on)
...just trying to help
 
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Old 03-15-14, 07:57 AM
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The sump and pump may have been placed as a preventive measure because when the house was built the contractor observed the footers were placed in the water table. To be safe, the contractor placed the sump and pump to keep the area dewatered and hydrostatic pressure off the concrete slab. The holes were placed into the sump to keep the sump from floating during installation. Just my 2.
 
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Old 03-17-14, 09:26 AM
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Thank you folks for your replies!!

Is it possible that your discharge pipe from the sump pump is not dumping the collected water far enough away from the foundation ? So that when your pump IS continuously cycling on, it is recycling over and over the same water??


Read more: http://www.doityourself.com/forum/we...#ixzz2wEimUXCW
Fairplay....I have thought about that too, but the discharge pipe empties about 20-25 feet from my house onto an area of yard that slopes away from my house. I'd assume that it's unlikely that that water is getting back under my basement slab. The pump is in my laundry room which is in the back corner of the basement. There is a concrete stairway and Bilco doors leading out from there. Water would come in from where the wall met the floor, right next to the door way. The contractor who put in the pump dug a 5' trench along that wall and filled it with gravel and a preforated pipe, which he ran into the sump basin. He left a gap along the wall with some type of hard plastic running along this gap (parallel to the wall), so that any water that came in would go down through the gravel, into the pipe and into the sump pit. He also drilled a bunch of holes in the sides of the plastic sump basin before installing it. When the pump is going off constantly, you can watch the water pour in through these small holes.

Landfillwizard....I had the sump pump put in 9 years ago shortly after we moved in. The previous owner told us that the basement had no water issues what-so-ever. It rained heavily less than 2 weeks after we moved in to the house, and we had water all over the laundry room, coming in where the wall meets the floor. Glad he was so honest.

Thanks again!!
 
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Old 03-17-14, 01:52 PM
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when the power took a dump, the water table only rose to a height still below your finished floor elevation - water seeks its own lever, runs downhill, takes the path of least resistance, & rushes to fill a void ( try making a hole in a sink full of water )

the holes in the sump are to allow water to enter the sump - otherwise the sump would float up out of the ground,,, think of your bsmt as a ship's hull below the waterline - its easier to understand - for me, anyway !

1 of the biggest jobs we ever undertook was a house in pa on top of a hill ! rainwater running down thru loose backfill + conc block bsmt walls +floating slab bsmt floor + 3mil exterior dampproofing done to code = new boat
 
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Old 03-18-14, 06:54 AM
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when the power took a dump, the water table only rose to a height still below your finished floor elevation -

Read more: http://www.doityourself.com/forum/we...#ixzz2wK1eSDYK
Stadry.......That makes it perfectly clear. That is what I was thinking was the answer, but wanted to post the question here because I just wasn't positive. You and a few others mentioned the holes in the sump basin are there to keep the basin from floating out of the ground, so that makes me comfortable that that was done correctly. Great example about the ships hull btw.

Thanks so much!!!
 
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Old 03-19-14, 08:08 AM
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Aren't you going to need a dehumidifier? To keep the moisture down? If there is a tank full of water all the time, I would think you would.
 
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Old 03-20-14, 07:19 AM
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Hi Vey.....I do have a dehumidifier which I run from spring to fall (in winter, the humidity level is around 40% or less). The dehumidifier keeps the humidity around 50% when it's running. Without it, the humidity level rises to approx 75%. I believe the sump pit is probably dry most of the summer as it rarely runs in summer and fall. Only after an exceptional rainfall (approx 4-6 inches) will it run. It's difficult to check because the sump pit is underneath my wash machine, and my wash machine is wedged between the dryer and a slop sink.
My sump pit cover is not sealed. The cover has about a 3" wide slit that runs from the center to the edge. The discharge pipe comes through that slit. I wish there was a way to seal that up.
 
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Old 03-20-14, 08:03 AM
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If the sump pit is almost completely covered with a plastic or otherwise waterproof cover, with openings just large enough for pipes, etc. to exit, then it won't let enough evaporated moisture into the basement to require a dehumidifier.
 
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Old 03-20-14, 08:52 AM
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AllanJ......Unfortunately, the opening is bigger than that. Picture a pie where you've cut out a piece, but instead of cutting a triangular piece, you start in the middle and cut out a rectangular piece. There is a pretty decent gap around the discharge pipe. Maybe I could tape some plastic over that space?
 
 

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