My sump pit was installed in the late 80s along with a french drain by the previous owner. I am considering making the put deeper, like 2' total. The current pit is about 16-18" and is made from thich black corrugated plastic pipe with concrete poured at the top.

I would like to leave the top portion undisturbed and dig down just below 2 feet. Are there any suggestions to how I might reinforce the lower part of the pit? I had been thinking that hand troweling a wall of high strength mortar with an embeded wire mesh might do the trick. Anyone have any success trying to accomplish a similar task? Could the bottom also be poured cement? Would weep holes be needed?

 

Why the need for a change? A sump pump fed by perforated drain tle may frequently have water in the bottom depending on the soil moisture.

If it has weep holes and is extended, you may be attempting to lower the water table around your home by a few feet. In that case you may expect the pump to run frequently for a year or two depending on the weather.

Dick

 

I also have to ask why? What would be the goal, or point, of making the pit deeper?

 

You both bring up good concerns. I should make an accurate measurement, but the original pit right was only a little over a foot deep and slightly more than a foot wide. When I attempted to put a battery backup system in a year or two ago, there was not enough depth in the pit to have both the primary and backup system working together.

In the summer when the pit was dry, I lowered the bottom a little... but I should have watched the weather, because the next day, there was a storm that came in and i decided to temporarily put things back together by placing the cutoff top of a thick pool chemical bucket in teh bottom ( about 4 or 5 inches ) and filled the sump back with rock.

So right now I still have a pit that has the emergency pump kick on when the water is less than an inch from the surface of the floor and I would like to go back and do the job right. Just trying to get advice on what right is.

I understand the concern that if I lower the pumping depth too much, I will pump water that would have never entered the basement, and I want to try to avoid that. My goal is to lower the pit at least as far as I have it now.. or more and then decide on the placement of the primary and backup pump depending on what makes sense.

I also have a backup gas powered pump that I used in a recent power outage/hurricane in NJ and for that system, I wouldn't care if the foot valve was 10' deep. In the case of a power outage, the more I pump, the more time I buy as the groundwater returns.

Thanks

 

The advantage of a deeper sump is that the cycle time for the pump is reduced. However, it will run for a longer period. I prefer that to the pump cycling every few seconds. Keep the drain at the same height and nothing else will change.

I have two sumps in my basement. One is an overpriced store bought sump while the other is just a plastic trash can. They are about 2' deep. My underslab drains feed from near the top.

 

Wayne,

Why would you prefer the pump to cycle so often. Doesn't that make the pump work harder? My pump will run for about 2 minutes to drain the sump and 4" french drain piping and then wait another 5-10 minutes to cycle back on. A deeper pit with a lower pump would result in more water pumped overall, but not sure that it would have a dramatic impact on cycle time. The water still has to filter its way into the french drain and be pumped out of the pit.

My goal is to get a slightly deeper pit and lower the primary pump a little ( few inches ), so that the emergency pump starts an inch or two below the basement floor.

I saw plastic pits sold at lowes/HD and they have a solid bottom, so I assume that I could do the same.

Still looking for the best way to form the bottom of the pit without the mess and time to disturb/remove the top.

 

You are correct. What I meant to say is that the time between cycles increases but the pump will run longer.

 

OK, good... knowing the 'why' will help you to get good information...

Obviously if the pit isn't deep enough to accomodate your pumps, then you do need to make it deeper.

But you said it's only a foot wide? In addition to making it deeper, I would suggest making it larger diameter also.

Check out this PDF for a bit of info that you may find helpful:

http://abe-research.illinois.edu/pub.../SumpPumps.pdf

 

Fixed link.

http://abe-research.illinois.edu/pub.../SumpPumps.pdf

Oh, I see the link is fixed.... Typed too soon I guess

Mike NJ

 

I was hoping that I could avoid breaking up the concrete floor to put in a wider pit. I measured the pump just now and the pit is 15" across and 12" deep. I have a smaller ( about 12" wide ) center section that is about another 4 or 5" deep.

I think the sump as is will be wide enough to satisfy what I need and the cycle times seem reasonable. The pump runs for 2 minutes and then shuts off for 10 in very wet conditions.

I saw a few DIY writeups that talked about concrete lined sump pits, suggesting that you pour a base first and then pour 3" thick walls using a form in the center. I think the complication with the plastic wall might make this difficult.

 

The pump should come on before the French drain pipes as seen in the pit are substantially submerged. Otherwise the French drain system won't desaturate the soil around the perimeter of the basement and flooding might resume particularly at the far side of the basement.

 

What did you end up doing. I have the same problem. I currently have a zoellar but I am always worried about it short cycling so I am switching to a glentronics with a dual float this way I can cut down the chance of short cycle. Let me know what you ended up doing.

 

Hi Mazzov,

Right now I have a plastic lined pit that is 15" wide and about 12" deep. As I mentioned, the center is slightly deeper.

I will.... when the damn thing ever dries out for a day or two... dig the pit to about 20" below the floor and form a concrete bottom and sides, like a giant cup.

I don't plan on disturbing the plastic liner, but I don't know if any of the rocks, dirt behind it will collapse when I dig. I want to make the walls strong enough to resist any pressure from the foundation nearby, but based on the sump's circular shape, it should be pretty darn strong. The concrete should also fill the voids of my dig nicely. I haven't decided on using any kind of reinforcing material, like mesh or rebar, but I don't think it will be required. I also want to mix this dry so it keeps it shape and has good strength. I would think getting rebar in with that kind of dry pack mix might be tough.

As far as materials go, I will have to ask for suggestions at the home center. Concrete? Mortar? Portland Cement? or something else? I had also considered using a form in the center, but I think a dry mix will be easy enough to shape and pound into place.

I guess I need to make some decisions soon.... wall thickness, material, depth. I had also thought of having the new concrete walls overlap the plastic a little. I may even drill a series of holes through the plastic walls where the concrete will overlap to make it more sound and get a good grab on the plastic.

I want to avoid breaking out the floor and replacing the entire walls. This is probably the smartest way to go if you have the nerve, a jackhammer and some confidence. I plan on trying to disturb as little as possible when I make my alterations.

 

You can get the benefits of the larger pit without the extra pumping work lowering the water table too much.

Keep the pump turn on relatively high, around where the underfloor drain pipes start to get submerged. PUt the pump turn off point down at the bottom of the pit, say the usual inch off of the very bottom.

When the pump does come on it will empty the pit. But during dry weather it may take a long time for the water level to rise to the level of the drain pipes and the pump will not run frequently.