Chicago inspection question

[shnikies]

Hi all! Thanks in advance for any advice.

I'm finishing the basement of a two story plus basement condo at Kimball and Irving Park. I'll be adding a full bath to the basement which has ceiling height of 7.5' with about 40% below grade. I have the permit for the work and the plans were self-certified by my architect.

I'm getting contradicting information from my architect and plumber. The former says the plans which have drains discharged to sewer by gravity flow is to code and the latter says an ejector pump is required. I have two questions...

1. Who is correct?

2. Regardless, if I choose to have the ejector pit and pump installed to play it safe, will the inspector have an issue with it since it's not the stamped plans?

Let me know if you need any more information.

Best

Kyle

 

[Jim Katen]

8 hours ago, shnikies said:

The former says the plans which have drains discharged to sewer by gravity flow is to code and the latter says an ejector pump is required. I have two questions...

1. Who is correct?

 

If the new drain piping can drain by gravity, it should. The only time you'd use a sewage ejector is when you have to pump the product uphill. "Who is right" will depend on the elevation of your sewer pipe. 

Quote

2. Regardless, if I choose to have the ejector pit and pump installed to play it safe, will the inspector have an issue with it since it's not the stamped plans?

 

It's not a matter of "playing it safe." Either your new plumbing is above your existing sewer pipe or it's not. You *must* use gravity if it's above. You *must* use a sewage ejector if it's not. Opinions don't matter here. Only reality. 

[Mike Lamb]

If you're building has an all gravity sewer system, I only see disadvantages with installing a sewage ejector for the bathroom.

Chicago § 18-29-712.1  Building drains below sewer

Building drains that cannot be discharged to the sewer by gravity flow shall be discharged into a tightly covered and vented sump, from which stack the liquid shall be lifted and discharged into the building gravity drainage system by automatic pumping equipment or other approved method.

[shnikies]

Thank you all!

[SNations]

In my experience, nobody with any authority in Chicago will notice -- let alone care -- that your installation doesn't match the plans.

Chicago has combined storm and sanitary sewers -- all the rain water goes out the same pipe as the poop water.  So Chicago used to have terrible problems with sewer water backing up into basements when it rained hard.  So to fix this problem, about 50-60 years ago builders stopped connecting any basement floor drain directly to the sewer.  They all went to an ejector pit, or sometimes just a basic sump pit if it was just for laundry discharge.  This has been the standard in Chicago for many decades.  

Even now, although Chicago has made great strides in stopping the sewer backup problem, all new construction that I see has an ejector system (an overhead sewer), regardless of whether or not the house drain can discharge by gravity to the city sewer.  It's just what everyone does all the time.  Even in the suburbs of Chicagoland this is pretty much all I see -- ejector systems.  I saw two new construction houses in Naperville this summer and they both had ejectors.  And nothing that I see prohibits this.  The code that Mike Lamb posted describes what has to be done if the building drain can't discharge by gravity.  But it doesn't prohibit using an ejector if you want to protect yourself from sewer backup.

Probably your plumber thinks an ejector is required because it's all he sees.  But I'd say that your architect is correct that a gravity drain meets any code requirement. 

I can imagine that some home inspector might see this when you go to sell the property and think it's weird that there's not an ejector and warn his client.  But that's the only reason you might want to go the ejector route. 

Steve Nations

[Mike Lamb]

5 minutes ago, SNations said:

The code that Mike Lamb posted describes what has to be done if the building drain can't discharge by gravity.  But it doesn't prohibit using an ejector if you want to protect yourself from sewer backup.

Installing an ejector pit isn't going to protect the basement from sewage back-up/flooding in this situation unless the OP is going to seal the basement floor drains which I don't think is a good idea.  Nearly all "newer" (post 1960) construction around here has overhead sewer so an ejector pit is a necessity whether there's a bathroom in the basement or not.

[Jim Katen]

If the idea is to protect against sewer back up, a backwater valve makes more sense than a sewage ejector. 

The only reason that a sewage ejector prevents backups is because of the backwater valve that's part of the discharge pipe. 

[SNations]

3 hours ago, Jim Katen said:

If the idea is to protect against sewer back up, a backwater valve makes more sense than a sewage ejector. 

The only reason that a sewage ejector prevents backups is because of the backwater valve that's part of the discharge pipe. 

Well, several generations of Chicagoans have disagreed.  Count me among them.

First, if there's a combined storm and sanitary sewer then a backwater valve can actually trap storm water and prevent it from draining out.  And you can actually flood your own house by running water when the backwater valve is closed.  Second, if the house drain doesn't slope much then a backwater valve can actually put too much resistance onto the sewage flow, slow it down, and cause sludge to build up.  Certainly over time this can happen even with good slope.

But mostly the failure mode of a backwater valve is terrible.  If it fails open then it's doing nothing to help.  And if it fails closed then it's trapping all the water in your house and it won't let you flush any of the toilets.

An ejector doesn't prevent backups because of the check valve built into it.  An ejector (or more properly, an "overhead sewer") functions because the high loop in the discharge line means that the sewer would have to back up not just to the basement floor to flood the basement, but several feet higher than that.  And if the sewer is backing up that much then you've got a lot worse problem to think about than your basement.

And if an ejector pump fails then you lose the ability to use things in your basement.  But you can still run water upstairs and you can still use the toilets upstairs.  So the failure mode is much much better with an overhead sewer than with a backwater valve.

[Marc]

9 hours ago, SNations said:

Well, several generations of Chicagoans have disagreed.  Count me among them.

First, if there's a combined storm and sanitary sewer then a backwater valve can actually trap storm water and prevent it from draining out.  And you can actually flood your own house by running water when the backwater valve is closed.  Second, if the house drain doesn't slope much then a backwater valve can actually put too much resistance onto the sewage flow, slow it down, and cause sludge to build up.  Certainly over time this can happen even with good slope.

But mostly the failure mode of a backwater valve is terrible.  If it fails open then it's doing nothing to help.  And if it fails closed then it's trapping all the water in your house and it won't let you flush any of the toilets.

An ejector doesn't prevent backups because of the check valve built into it.  An ejector (or more properly, an "overhead sewer") functions because the high loop in the discharge line means that the sewer would have to back up not just to the basement floor to flood the basement, but several feet higher than that.  And if the sewer is backing up that much then you've got a lot worse problem to think about than your basement.

And if an ejector pump fails then you lose the ability to use things in your basement.  But you can still run water upstairs and you can still use the toilets upstairs.  So the failure mode is much much better with an overhead sewer than with a backwater valve.

So,,, a high loop is better than a backwater valve?

[Mike Lamb]

19 minutes ago, Marc said:

So,,, a high loop is better than a backwater valve?

Yes.

[Jim Katen]

I can appreciate Chicago's unique take on this. But it's just that, a unique take. As well as it might work, it's at odds with the UPC. In aggregate, I find the arguments in favor of the ejectors weak and not particularly compelling. Like many other things in Chicago (Romex, anyone?), I suspect that the prevalence of ejectors is more about job security for plumbers than it is about how well the system works to stop backflows. 

Just for the record, the UPC requires the backwater valve to only serve those fixtures in a house that are below the elevation of the nearest sewer manhole cover. Fixtures higher than the manhole cover are prohibited from having backwater protection and don't need it anyway. 

Both backwater valves and ejectors systems can fail, although I concede that the ejector system has an advantage because of the high loop. On the other hand, there have to be lots of failing pumps out there at any given time.