Sump Pump Pit odor?

[Bill Howatt]

My neighbor has a sump pump pit that her washing machine empties into via a laundry tub sink and a sump pump automatically pumps it out to the septic tank leaving a bit of water in the bottom of the pit. The line from the sump pump goes about 3" above a line from the kitchen and bathroom sink at the basement ceiling and then downward tees into this line which then goes to the mainline to the septic tank. The septic tank mainline is a few feet below this sink drain line. In the past few months there has been an odor in the house, basement primarily, that seems to be coming from this area. Doesn't smell like a sewer smell but, IMO, more like a vinegar cole-slaw smell. Strange thing is this setup has been in use for over 40 years and is just now becoming a problem.
She had a one-way trap put on the pipe from the sump pump to the septic tank in case the water level was dropping too low in the pit and uncovering the pipe end but this doesn't appear to have helped much (yet?). There are no other plumbing issues in the house. She has put some bleach in the pit and may use a little on some laundry days but being on septic tank it isn't overdone.
I know this is vague but has anybody experienced this or have any ideas?
Thanks.

[George Yetka]

Would this sump see water if they didnt dump washing machine in it?
I would go easy on the bleach if its hitting the septic tank as you will kill bacteria you need. A little is Ok
Are they doing more wash than usual?
Soap and hair hair can form an awful smell in traps It could be that hair and other biologics from the clothing have built in the pump and mixed with the soap is giving you that smell

[Bill Dufour]

For machine tool coolant sumps many drop a aquarium air pump hose and air stone into the tank to keep it aerated to reduce stick form anaerobic bacteria.
Bill D

[Earl McLain]

I wonder if a cake of yeast might relieve that odor over time?? We flush a packet of dried yeast down one of our toilets a few times a year, supposed to promote good bacteria in the septic. Reading the posed problem made me think of the old style yeast cakes--in our case the sump pit is the furthest from the septic, seems like the cake might dissolve slowly enough to work there. Again, just a shot in the dark...don't even know if yeast is still sold that way!!

[Bill Howatt]

Thanks for the replies!
I doubt the sump pit is handling anything more than the washing machine grey water. I'm 2 blocks away on the same very, very sandy ground and don't even have a sump pump.

Going to suggest a first step is a complete cleaning of the pit from top to bottom - not just putting bleach in the water which would not touch above the the range the sump pump operates in. A good scrubbing could well be more effective than just a small bleach "rinse".

[Bill George]

You don't suppose it could be the smell of a sump motor starting to burn out?

[Ernie Loposser]

without more info im suspecting the basin lid seal is failing. The seals that come with the jackal basin lids are apt to leak after awhile. I just installed sewer pump system for a basement bathroom and laundry. I didnt use the included lid seal but purchased a more rubbery/thicker seal.

[Bill Howatt]

Definitely not a problem motor.
The pit is not tightly sealed - it has a probably plywood cover and but there are larger than required gaps so the laundry and sump output pipes.
Thanks - I think fixing that up after a good cleaning is step #2.

[Dan Hunkele]

It's the lint in the washer discharge water. I put a women's nylon knee high stocking on the end of the hose to catch the lint and still have to put bleach in the hole at times. The water turns black before the smell starts. It is extra maintenance. The lint has to be cleaned out of the stocking on a regular basis. I'm surprised at the amount that gets caught and how tight it can clog the nylon stocking. They really should reroute the line separate of their septic.

[Tom Bender]

If the lid's not tight a mouse might have fallen in