Occasional Sewage Smell in Basement

[scofopolis]

Prior tenants mentioned that there was sometimes an intense sewage smell in the basement. We moved in a few days ago and noticed it for about 15 minutes - then it went away.
Basement has a sump pump (pics here: ) - wondering if it is coming from there?

In hot water tank room there is another pump system (for waste I am assuming). I noticed around some of the pipes (where they screw into one another), there is dried brown residu. Could this be the source potentially? Some gas / sewage leaking out when the pump is activated?

I'm not very adept at plumbing, so apologies if this question sounds a bit silly. Thanks in advance for the help!

 

[Helper Dave]

A ground water sump pump is rarely the source of sewer smells. Maaaaybe there's ground contamination from broken sewer pipes, or funky smelling clay or dirt.

The ejector pump would be a more likely candidate. That's pumping out everything going down your basement bathroom pipes. If those pipes are leaking, or the pit isn't air tight, that would be a problem. Watch it when it turns on ("force" it by flushing a toilet a bunch, or running a sink for a while). Does it actively leak? Any air noises, or whistling sounds? Does that kick up the smell?

One of the most common sources of sewer smell in a basement is a dried out floor drain, though. Slowly pour a few containers of water down to make sure they're full. This is worth doing every couple months if there's nothing draining down there (condensate lines from your furnace, or dehumidifier, for example).

 

[scofopolis]

Hey there. Thanks for the reply. I’ve been doing a lot of reading about this.

1) the sump doesn’t fill if I’m running water in the house. I’ve noticed there is about 2-3 inches of stagnant water in the sump pit. I tried to manually lift the buoy thing to activate the pump. It sucked some up but eventually the water line fell below a certain level that was not getting sucked by the pump. As such - I release the buoy thing but then some water spits back out (probably because no check valve was installed). In any case, I do believe the stagnant water is emitting a very light smell. I will manually dump lots of water in that pit to slowly recycle the stagnant water.

2) in terms of sewage smell - I’m still unsure where that came from.Like I said, it only happened for a few minutes. I did notice our apartment (ground floor) has a few sewer drains in close proximity - in fact, it smelled of sulfur outside the other night when we were out on a walk. I don’t see any floor drains as there is flooring installed - could there be a floor drain potentially under that flooring? Plumber is supposed to come Monday - if it is a floor drain issue, that means flooring will have to be removed?

thanks for all the info! I’m learning a lot!

 

[Jeff Handy]

All your tinkering and theories and ideas so far are good, you have good instincts.

As mentioned above, the ejector pit or drains leading into it might be cracked, releasing stink water under your concrete floor, which can travel through the gravel layer and enter your ground and rain water sump pit.

There could also be a problem with the vent piping on the ejector pit.

 

[scofopolis]

All your tinkering and theories and ideas so far are good, you have good instincts.

As mentioned above, the ejector pit or drains leading into it might be cracked, releasing stink water under your concrete floor, which can travel through the gravel layer and enter your ground and rain water sump pit.

There could also be a problem with the vent piping on the ejector pit.

Interesting….and how the heck do I figure this out / get it fixed?

 

[Jeff Handy]

You could open the cover on the ejector pit and pour in some strong food coloring.
Then if that coloring makes its way into the groundwater sump pit, you know there is a leak in the ejector pit or sewer pipes under the slab.