Sump basin - drill holes?


Old 05-10-12, 10:01 AM
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Sump basin - drill holes?

I have been looking around for an answer on the net but have not come up with a definative answer so here I am.

I have a sump pit that is approx. 18" diameter and 22" deep. The pit is solid with no holes except for two inlet holes cut into it accepting 4" drain tile from the french drain installed in my basement. The pipes come in above the level to which the pumps are designed to kick on so it seems that water will only enter the pit when the level below the slab reaches the drain tile. I am in a high water table area so whenever there is a significant rain, the sump will fill up and the pump will kick on. The sytem works great and haven't had flooding since it was installed.

My question is: should I drill hole holes into the pit below the inlet holes and/ or in the bottom of the pit? I have read about basins being sold with the holes already drilled in them and others where the bottoms were cut out from them. Since my system has been working flawlessly I am reluctent to mess with it. But when Hurricane Irene hit (I am in northern NJ) the pumps were working in overdrive coming on several times per minute. I realized that a larger sump basin would have allowed the pumps longer intervals between pumping. That is what made me think: if I drill holes in the basin, would that allow the water more area to fill up (gravel around pit, water level below the drain tiles) before the pump needed to kick on? Would the pump stay on longer at shorter intervals? Hurricane Irene is an extreme case so I then think since I am in a high water table area, the pump only kicks on when the level is high enough to reach the drain tiles and fill the sump pit. If I were to drill holes in the basin, if the water level is below the drain tile but high enough to cause the pump to kick on since the water is now able to fill the pit before reaching the drain tiles, then potentially I could have the pump kicking on unnecessarily on a regular basis. So, would there be an advantage to drilling these holes?
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Old 05-10-12, 10:18 AM
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There is nothing wrong with the sump pump running much if it does the job. I run my furnace fan 24/7 for more than 6 months a year and then intermittently during the remaining times.

Keep in mind that whenever the pump is running, it is removing water that can cause moisture or structural problems for a home.

Many people drill holes in the lower portion/bottom, place rock and sand to act as a filter under the pump to increase the effectiveness of the sump pit and lower the ground water level under the house. This is effective to reduce the hydrostatic pressure, especially under a slab.

Old 05-10-12, 01:51 PM
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I drill holes and fill around the outside of the basin with clean gravel. I think it helps to remove from underneath the slab a bit better instead of relying on the water rising to the level of the drain pipes.
Old 05-10-12, 03:13 PM
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If you are sure the sump is surrounded by gravel then it would be safe to drill holes if you like. BUT if they used sand to fill before installing the gravel under the slab you might cause this sand to wash into your pit! This would cause 2 problems if you drill those holes..First the pump would be pumping that sand and wear out faster. Second there could potentially be a void created under the slab as the sand washes out. This could lead to the slab cracking and beginning to leak water in at the crack. That could lead to bigger problems and lots of cost.
If it is working well now I would leave it as is. Leave sleeping dogs lie, so to speak.
Old 05-10-12, 03:56 PM
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I wouldn't change anything that you have. It works. If you want longer run times, get a smaller pump, but I don't think that makes sense. I think it is obvious that the pumps provide far more capacity than you need during extreme situations. I find that to be a positive situation.

Buy the way, do you have more than one pump in the same pit?
Old 05-13-12, 07:52 PM
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Thank you all for your responses. After Irene my Champion CPS3V 1/3hp pump 40gal per minute (10' head) and my Watchdog Bigdog battery backup were running simultaneously (they share the same pipe. I never anticipated needing both to be running at the same time) and I had to throw in a small utility pump with the hose out the window to just barely keep up. That was a wake-up call for me that the battery back-up wouldn't have standed a chance if the power went out. I think the two would have been enough had I had two outlet pipes instead of a shared one. To prepare for the next extreme storm and not have to worry about the pumps keeping up, I installed a Zoeller N98 running a seperate outlet pipe. The Zoller might be considered overkill to many but my Champion is 7yrs old and I am worried that it might conk out one day. So I have 3 pumps installed in the one pit (tight fit). I have the float switches set up so that the Champion runs the day to day pumping when we get a significant rain. If this pump gives out or can't handle the flow of water then the Zoller will kick in and the two should make short work of the worst conditions. Now only if the power goes out will the Watchdog kick in and it should be able to handle the regular water flow that the Champion deals with without any problem. If the storm of all storms is anticipated and the chance of losing power is imminent, my emerency generator will keep all of the pumps going and me sleeping soundly.

So, back to my question about the holes. I think I am just going to leave things the way they are. The pit is surrounded by stone instead of sand so the holes would work but since I have the high water table (I even think there is an underground stream that runs through my house) I feel like the pump will always be on even though the water level is below the drain tile. I would love it if I could lower the water level but I am afraid that since there is so much water in my area I may never be able to lower the level and wear out a pump in the process.
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