I live in frozen Chicagoland. I need to discharge a sump pump pit to the outside. I cannot connect to the storm sewer and I cannot drain to daylight. I was thinking of digging a hole for a drywell...

I wont be able to get the discharge below the frost line. The 2" discharge exits the house above ground. I was going to put an air gap in right where it exits the house (thinking if something froze it would overflow, correct?). Then when it gets into the ground next to the house I was thinking either flex pipe or 4" pvc. Buried about 12-24" and sloped for about 20 or 30' from the house where I would dig a hole for the plastic drywell with an overflow on top.

I notice the sump pump running even in the winter sometime so I fear freezing. Am I going to have issues from what I describe? How would you do this in a freezing climate?

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You could use a larger pipe to prevent it from freezing shut.

thanks for the link... that's what I had in mind but I was worried about depth. Is what I describe a non-standard setup for a freezing climate?

Its hard to say, I have heard the saying running water never freezes. We have a 4ft frost line in Massachusetts. It is a good idea to have a over flow in case the line freezes. A longer discharge pipe would probably freeze faster than a shorter one. You could put the pipe and dry well deeper but the plastic may not be able to handle the weight. Does Chicago still dump storm water in the sanitary sewer?



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Chicagoland, Chi-Town, Chi-Raq and "The Region" has been pretty lucky this winter with a little snow and a handful days of Zero weather.

Digging a pit during the winter is never that easy if you are using a shovel and must dig deep to be effective. Flexible PVC has ridges. Used on the outside of the building, can freeze and the discharged waters freeze in the ridges. I would consider using 1-1/2 inch solid pvc. Install the solid pvc on an angle so it empties on the ground. I don't feel it will freeze, as long as the piping is on an angle. Once winter passes and it will do in less than 60 days you can dig the soil and clay up and build your self a dry well.

I would suggest that instead of a dry well, you angle the sump waters to a ditch in the front of your house, or the curb.
Best Wishes

No matter the length or slope, is it fair to say if the ground is frozen it wont saturate and the well will overflow / freeze the discharge?



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The ground top soil might be a tad frozen, but if you go down 3-4 inches, it is not.

Best Wishes

The discharge must exit the house underground and remain underground for its entirety or you are only headed for trouble.

that's what I was worried about, please elaborate on that.


fwiw, the exposed part is vertical.... there would be an air gap too. Seems like going out of the foundation underground (above the frost line) is more dangerous since you would not have that gap as a freeze precaution.

Don't worry about the pipe being within the frost line. As long as the pipe continually pitches away to the disposal area, you will be fine.

a I did this project and I live in a NW suburb of Chicago. I'm in a valley and get a lot of ground water and it was pouring onto my front walkway and driveway and turning into ice. I dug the large hole myself in about 2 hours on a warm day (april 15'). My neighbors helped me with the trench and digging a little deeper in the large hole to get the drywell pop-up level to the ground surface. I haven't had any freezing issues nor have I needed to scrape any ice from my air gap. When digging the trench I was mostly concerned about having the pvc deep enough to not interfere with a new concrete walkway that will go on top at some point in the future. The top of the pipe starts about 1 foot below the surface and as it gets closer to the drywell it is about a foot and a half below the ground surface. The drywell had mini holes for drainage and 4 inch holes for inlet pipes. The catch basin has a 4 inch outlet. I already had long sections of 2" pvc so to save money I went from 4" to 2" to 4". The two regrets I have is that I didn't buy a plastic bottom for the drywell (the pop-up and bottom are sold separate and cost about $30 each) and the drywell is located directly above my clay pipe sewer drain that has porous cement joints. At least the soil type appears to be clay so the bottom isn't draining quite as fast as other soil types. I also could have gone at least another 5 feet away from the house. I poked out at least a dozen drain holes on the side of the drywell farthest from my house. I originally glued the pvc pipe in the trench and then realized that a rigid connection underground isn't ideal so I cut of those joints and redid it with the flexible couplings. My sump pump went off an hour and a half apart even though it was at least the second consecutive day of single digit temps.









Filling the hole


Air gap


Air gag close up


Inside mini catch basin (below air gag). Note that the basin has a shallow recessed area that holds an inch of water before it drains horizontally through the 4 inch opening. Pic taken today 1/23/15. temp was 30 degrees.


Finished product


My sump pump is a 2/3 hp very good brand with a 2" discharge but it's located on the opposite long side of the house and the piping inside the house rises in at least two different spots creating substantial head pressure. Looking at rerouting the discharge line somehow in the future as it rumbles my sons bedroom floor.



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thank you for posting that!

So this "catch basin"..... im not clear. The 90 underground at the house, it not just a normal fitting?

I think the top was a 6 inch inlet and the horizontal at the bottom is a 4 inch outlet. Got it at a big box store



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thanks again.

What the benefit of using that catch basin instead of a standard 90 ?

The basin will be less likely to tilt or lean to the side because of its flat bottom. I just slid the 4" PVC into the grooves of the horrizobtal outlet and it fits very snug. I may have used black tile tape to really secure that connection (I can't remember). I slid the 6" green piece snugly into the top (no grooves but it's snug and has gravity helping out). The 4" pipe going into the drywell isn't sealed so it can rotate freely if the catch basin is disturbed.

Because the basin empties slower than it fills, I made sure the green piece was tall enough so that water won't overflow out the top.



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I also want the same help.

I'm not a plumber but I can gladly provide tips or pointers for this specific outdoor project



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