Our single story 1950's home had an addition added in 2000, the addition included a second basement level (approx 1 foot lower than original), and both a sump pump and sewage ejection pit were installed. (We have no issues with the sump pump, it is a separate entity and is not tied to the sewer.)

The Sewage Ejection System was installed to control the waste of a NEW 3 piece bathroom built into the lower basement, and appears to have introduced chronic sewage smell issues whenever the pump cycles. The smells are consistently worse in the fall and winter months when the house is closed up and heating is on. It also appears the smells are much worse when the washing machine has been running a few cycles (although the washing machine drains into a separate sink in the original basement, and that sink feeds directly into the main sewer line). The odour is predominately in the basement, however can be detected on the main floor on a regular basis as well.

The sewage Ejection system has been inspected NUMEROUS times by several plumbers none of whom have identified root cause. The following correction measures have been taken over the past 9 years;
* smoke test/pressure testing has been completed and the system passed.
* separate venting was installed for the ejector pit and the lower bathroom
* sewage ejector pit pump has been replaced due to an early malfunction (after 2 years)
* sewage ejector pit lid and seal have been replaced several times, and sealed with extra caulking
* venting system has been placed on laundry tub
* replaced in house sewage pipe between mainfoor and to floor of basement.
* sewer line has been snaked and video camera confirmed no blockage in the line
* Floor drain was cleaned and has since been sealed with mechanical plug to ensure no leakage of odour
* Sewage cleanout was also sealed with a mechanical plug

Recommendations for next steps have been to dig up the sewage ejection pit and replace it - implying a crack in the original construction and possible sewage leaking into the ground under the house? OR... dig up the entire basement and source a problem which may exist under the house along the main sewer line enroute to the city connection at the street.

Both are extensive work and expense, do you have an opinion or expertise in this area?

This chronic problem is really frustrating.

Thanks!

Are there any other floor drains in the basement that may be tied to the sewer system, or a slop sink? I know you said the drin was sealed but there are usually more than one. Sniff the plug area around that floor plug, any odor at all?

Hi, no actually there are no other floor drains, the 500sf basement is all exposed concrete flooring and the addition 400sf is also exposed concrete except for the new bathroom which is on a raised wooden floor. (note in our attempts to find the odour we also pulled up the newly finished bathroom and triple checked all drain seals, and repositioned fixtures)

The main sewer line is in the original basement area, about 12" away from that stack in the floor is a mechanically sealed floor drain. About 24" to the left of the main sewer line (on the opposite side of an interior wall) is another simliar drain in the floor - also mechanically sealed and caulked with silicone, plumbers have indicated this is a sewer cleanout access. No odour... we've done several tests to ensure water tight.

There is a laundry basin immediately beside the main sewage line - the pipes to that tub have been replaced (from cast iron to PVC?) the line goes direct into the main sewer line and vent has been added (by the last plumber). The washing machine drains into the sink. No odour is detected from either the laundry tub drain, or the drains in the basement addition area bathroom.

Note that we also replaced the main stack from about 1" off the floor through to the main floor with PVC. This did not make any improvement or change in the odour problem.

The strongest concentration of the odour is about 1-1/2 feet behind the sewer cleanout access along the original foundation wall of the back of the house (now an interior wall separting the addition from the original house).

Is it possible that the main line is cracked or compromised under the house by the pressure applied when the ejector pump forces sewage through the line? And if so if the foundation wall has hairline cracks (after jackhammering and building the addtion) could sewage or the odour be seeping through the ground up or through the wall?

The odour is not present when only the main floor washroom, dishwasher or sinks are used. The odour is very very strong whenever the sewage ejector system has run.

Thanks again for any help!

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separate venting was installed for the ejector pit and the lower bathroom

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Were any of these vents tied back to other vents? Especially the pit vent.
Does it run outside by itself?

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Is it possible that the main line is cracked or compromised under the house by the pressure applied when the ejector pump forces sewage through the line?

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Very doubtful. The pressure isn't great enough to burst the pipes.
Regards, tom

It is now separate. Originally the new bathroom fixtures and the ejector pit all vented out in one new vent. As part of our troubleshooting we installed a NEW separate vent putting the ejector pit on it's very own venting up through the house, through the roof and outside.

It's a tricky one to solve we have had at least 6 different plumbers 4 different companies try to solve this!

Okay, they have done a scope, and no cracks in the sewage pipes in that area you speak of that could be seen?
(ejector wouldn't cause crack, but remodeling could - wouldn't be the first time)

They did a smoke/pressure test - after installing new vent for ejector? Did they check on the roof to ensure they took the cap off that new vent after doing the test? (happens)

How far from the ejector is the laundry room and the area of which has the most concentrated smell?

Is your check valve working properly.

Correct, scope was done and no cracks were visible.
Correct, smoke test was done and we have since confirmed roof vent is not blocked.
Ejector is about 15 ft from the laundry room.
The smell is strongest in the original basement on the opposite side of the foundation wall.
The ejector pit is in house addition's new lower basement, while odor is mostly found about 8ft away on the opposite side of the foundation wall in the original basement. Laundry is an additional 7' away in the original basement, near the sewage line.

Re: is the check valve working properly, I don't know if this has been tested, can you tell me how to test it?

Thanks!

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It is now separate. Originally the new bathroom fixtures and the ejector pit all vented out in one new vent. As part of our troubleshooting we installed a NEW separate vent putting the ejector pit on it's very own venting up through the house, through the roof and outside.

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So you now have two vents. One dedicated vent for the pit and another vent for the fixtures. Is that correct? Let me know, Tom

Yes that is correct Tom, the basement bathroom has two separate vents. One for the shower and sink and toilet. Second one for the pit.

The house has a third original vent that is totally separate for the mainfloor kitchen and bathroom.

The pit vent. Does it run out the roof by itself or is it tied into another before it runs out the roof? Back to you, Tom

Hi Tom, the pit vent goes out of the roof by itself not tied to any other vents. Next :)

Hi Tom, the pit vent goes directly out the roof and is not tied to anything else. (believe me it was tricky installing it through the basement ceiling main floor floor in the cavity between two walls, and then up through the attic directly outside). Back to you! Brennr

How about the lid on the pit? Any odor around that? The fixture dtains?

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* Floor drain was cleaned and has since been sealed with mechanical plug to ensure no leakage of odour

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Some floor drains have a 1 1/2" threaded plug near the top.(see image) Was the plug in or out? Let me know, Tom

Hi Tom,

Re the floor drain - I would have to unseal the drain to look at that. Give me a couple days to arrange to have someone over to help me remove the mechanical plug (it's on really really really tight). I don't recall seeing any kind of cleanout plug around the rim. To me it just looked like a hole in the floor, and I could see water sitting in what appeared to be a trap.

Your other question about any odour around the pit lid, no, no odour there.
And no odour around the fixture drains either. Odour is predominately in the vicinity behind the interior foundation wall closer to where the floor drain and main sewer line are.