Hub drain for three basin dish sink

[brr]

We are designing a new cafe in an existing unoccupied food service tenant space The building owner is removing and replacing the slab in the commercial kitchen room. We are planning to put sinks in the existing now empty kitchen and there are no existing below floor drain pipes on the kitchen side. It was formerly a commercial kitchen and the space is now vacant, but we don't know where any sinks were located previously - there is a hole punched through the wall above the hub drain.

We are still in the planning stages of the cafe design and don't have a contractor or plumber yet. I have made an appointment to talk with a city official, but that will be on Wednesday.

Does anyone know if draining both kitchen sinks directly to the hub is allowed here and/or what code section addresses this? I'm advising the building owner to put a floor drain on the kitchen side and rough-in a drain for the new sinks and he's resisting doing the extra work.

 

[Gregg Harris]

When you say "hub drain" are you referencing an open site drain? What size drain?

 

[ICE]

What plumbing code is enforced?

 

[Joe.B]

Assuming similar UPC based codes in Oregon:

Table 702.1 generally tells you what each fixture counts as in fixture units, i.e. "sink, commercial with food waste counts as 3 fixture units. Table 703.2 tells you how many fixtures a drainpipe can handle, i.e. a 2" horizontal pipe can handle 8 fixture units. So, if your existing floor drain only has a 2" drain, it will likely be overloaded if everything you show there tries to drain through it.

Table 702.1 has footnote 1 which says, "Indirect waste receptors shall be sized based on the total drainage capacity of the fixtures that drain thereinto, in accordance with table 702.2" So check that out too.



The way it was explained to me early on was this; fill up all three sinks, put a 5-gallon bucket under the drain and pull all the stoppers at once. Based on how fast the bucket fills up, you can calculate your GPM. So instead of your 3-compartment sink only counting as 3 fixture units, it will probably count as 4-6. But that's better than counting as 9.

I've had a few unpermitted additions to commercial kitchens come to my attention because of overloading floor drains.

 

[brr]

Assuming similar UPC based codes in Oregon:

Table 702.1 generally tells you what each fixture counts as in fixture units, i.e. "sink, commercial with food waste counts as 3 fixture units. Table 703.2 tells you how many fixtures a drainpipe can handle, i.e. a 2" horizontal pipe can handle 8 fixture units. So, if your existing floor drain only has a 2" drain, it will likely be overloaded if everything you show there tries to drain through it.

Table 702.1 has footnote 1 which says, "Indirect waste receptors shall be sized based on the total drainage capacity of the fixtures that drain thereinto, in accordance with table 702.2" So check that out too.
View attachment 16144


The way it was explained to me early on was this; fill up all three sinks, put a 5-gallon bucket under the drain and pull all the stoppers at once. Based on how fast the bucket fills up, you can calculate your GPM. So instead of your 3-compartment sink only counting as 3 fixture units, it will probably count as 4-6. But that's better than counting as 9.

I've had a few unpermitted additions to commercial kitchens come to my attention because of overloading floor drains.

Thanks for the reply. I assessed the drain size to be 2" just looking down on it.

So, I'll say I consulted an official (maybe a fib, but it could save the owner lot of extra work).

I had wrote about this job previously on this forum after the owner raised the slab on the kitchen side (it was a sloped ramp leading to a car repair shop) to level out the kitchen, but this action reduced the distance to the kitchen exhaust hood... It turns out he had his handiman to the work, so, I'll assume he'll have his guy put the drain in through the wall too, but I'll insist he get a plumber. It sounds like you are saying a 3" pipe minimum.

I'll hope the owner does the right thing.

The hub drain in question is to the left. The only "drain" from the kitchen side is that 3/4" galvanized pipe you see above the hub drain.

 

[e hilton]

There is a note on the plan “new slab level with existing cafe floor” but there is 2 steps down between the rooms.

Can you swing the mop room door out? The in-swing takes up a lot of space in a room that is probably already too small.

 

[brr]

There is a note on the plan “new slab level with existing cafe floor” but there is 2 steps down between the rooms.

Can you swing the mop room door out? The in-swing takes up a lot of space in a room that is probably already too small.

Good suggestion on the door - I guess the question too is, would that wall be valuable to hang mops or brooms or workers aprons... We are relocating the door from the restroom because the toilet can't meet ADA in its current location so we have options on the door swing.

The floor slab is coming out and will be lowered. The saga of that is discussed here in an earlier post.

 

[Yankee Chronicler]

3-bay sinks I've reviewed recently all had at least a 3-inch drain line. And don't forget the grease interceptor.

 

[Joe.B]

Thanks for the reply. I assessed the drain size to be 2" just looking down on it.

So, I'll say I consulted an official (maybe a fib, but it could save the owner lot of extra work).

I had wrote about this job previously on this forum after the owner raised the slab on the kitchen side (it was a sloped ramp leading to a car repair shop) to level out the kitchen, but this action reduced the distance to the kitchen exhaust hood... It turns out he had his handiman to the work, so, I'll assume he'll have his guy put the drain in through the wall too, but I'll insist he get a plumber. It sounds like you are saying a 3" pipe minimum.

I'll hope the owner does the right thing.

The hub drain in question is to the left. The only "drain" from the kitchen side is that 3/4" galvanized pipe you see above the hub drain.
View attachment 16145

I am an official, just not your official. Yes, probably a 3 inch. Or, multiple 2". Tell him to hire a contractor and get a permit, if not, you want a hold-harmless agreement. This isn't in Beaverton is it?

You can mail the check to "The Building Code Forum" at.... @jar546

 

[ICE]

Your code might look something like this:

 

[brr]

Your code might look something like this:


View attachment 16155

Thanks ICE, that's the ticket!

 

[brr]

I am an official, just not your official. Yes, probably a 3 inch. Or, multiple 2". Tell him to hire a contractor and get a permit, if not, you want a hold-harmless agreement. This isn't in Beaverton is it?

You can mail the check to "The Building Code Forum" at.... @jar546

Portland. I've never had any projects in Beaverton, but when a client first contacts me and I find out they are in Portland, I sigh and know to estimate half-again as much for my design time. While I know every jurisdiction has it faults and particularly difficult staff, I've never encountered anything like Portland. Waiting three or four days for 15 minute video conference is the norm - that's the department's preferred way of interacting with the public. However, in the "old days", about one out of three calls were never returned, so I appreciate the certainty the scheduled video chats provide. You can still get just a call back, but with the same old no guarantee... My meeting on this topic was scheduled for tomorrow, but I canceled it after the owner agreed to get his plumber out there - it helped to send him to the the 704.1 tables with a little explanation and no fibing was needed in the end!

 

[ICE]

Be aware that I said that your code MIGHT look like that. Not all jurisdictions require a direct connection and might approve an indirect or even require an indirect such as an air-gap over a floor sink. What I thought would help you with the client is the news that a floor drain is required with a direct connection.

 

[Joe.B]

Oregon uses the Uniform Plumbing Code as a model code, as does California, so you do likely have that section that @ICE is referring to. You probably also have this section:

And, unfortunately, as @ICE is also pointing out, there's the code, then there's what local jurisdictions actually enforce. For example, there is this section that literally nobody enforces.

When I was the inspector, I enforced it, and it was a battle every time. After fighting it for years I began a widespread effort to communicate with other jurisdictions in NorCal (beyond my little redwood curtain bubble) hoping to find support, but no, I found I was alone on a hill. When I took the promotion and hired an inspector, I told/showed him the code and explained it, then said it's up to you if you want to join the masses or stand alone.