A question for the plumbers

TonyS

I just bid a job that requires two grease traps, each one serving its own triple bowls sink.

The code in this township requires that the sink be connected to the grease trap through a indirect waste. Has anyone here used this configuration and how do you stop the floor sink from overflowing?

Dave Yates (GrandPAH)

food prep or dishwashing?

If food prep sinks, then that's the correct method with each bowl having a separate line to the floor sink with an air gap 2x the pipe diameter and a domed strainer inside the waste receiver.



However, if those are sinks designated for dishwashing (meaning they cannot, in theory, be used for food prep work because the bowls are considered to be contaminated), then the commentary edition of IPC indicates in several passages that not only is that wrong, it creates "a known health hazard".



Never a dull moment for codes interpretation at the local level!



One local twp allows fernco couplings above grade and no-hubs below grade only while a neighboring twp has the exact opposite rule. Another twp requires a 6" sanitary sewer line be run into any building designated as 'commercial'. Once did a strip mall with each store having just a 1/2-bath & 1.6-GPF water closets & we had to install 6" house traps sets for each one! The head scratcher - soon as you penetrate the building's foundation wall you can reduce to 4". Go figure.

icesailor

Code Interpretations:

Glad I work and live in Massachusetts where we have a "Uniform State Plumbing and Gas Code". One that applies the same in every city and town in the Commonwealth. Local inspectors have monthly get together's that are required so they can keep up with what is current. There is no local BS. And inspectors "That like to see it like this" can be put in their place by the board. None of this one town wants it like this while another town wants the opposite.

Some jurisdictions may have PITA inspectors but they all read and use the same code books as the rest of us.

meplumber

Amen to that Ice.

Here in Maine we also use the Uniform Code statewide.  Cleaned up a lot of the town to town variances.  We used to have an old state code that might have well been written in pencil. 

Robert O'Connor_12

Try this!

Try this and see what the inspector does (At least in NJ)! Size the grease trap @ 75% of ONLY the wash bowl. There are 3 bowls, one is wash, one is rinse and the last is for sanitizing, right? Now read (interpret) the code section. "Waste waters that are not grease laden and do not require separation shall not be discharged into any grease interceptor."

Most inspectors don't know this and most manufacturers won't tell you this! Great way to save $$ and make a more effective way to capture the grease.



Robert O'Connor/NJ

TonyS

Dave

I believe that is exactly whats going on here. These are dishwashing sinks, but the problem is I am the out of town plumber. I just want to do my thing and pipe it like they want ,get my money and go home. That being said, lets pretend they are a food prep sink. How do you control the flow rate to the grease trap? By installing flow restrictors on each individual drain from the sink before entering the floor sink?

Thanks

TonyS

Thanks Robert

considering the price of grease traps I will give that a try.

Robert O'Connor_12

TonyS

Be careful, many inspectors will have you believe this method isn't correct (It's how they were taught). You would have to prove it to them first which isn't always easy. I would write all calculations down first, then include a copy of the text (code) and it would help to have the support of the adopting administrative authority (State). I can't speak for any other state other than Jersey.

Good Luck!



Robert O'Connor/NJ

Charlie from wmass

Robert that rule makes sense, BUT

yes a big but it does not apply in Massachusetts code. We need to size to the whole three bowls and the other grease fixtures such as dishwashers. New places put 1000 gallon tanks underground outside and have dedicated lines going out.

icesailor

Grease Interceptors:

And that puts an end to ALL Massachusetts questions about Grease  Interceptors.

And the Interceptor isn't a "Trap", it's an interceptor that must be vented and traped AFTER the interceptor. So it doesn't become "double trapped".

icesailor

Grease Interceptors:

And that puts an end to ALL Massachusetts questions about Grease  Interceptors.

And the Interceptor isn't a "Trap", it's an interceptor that must be vented and traped AFTER the interceptor. So it doesn't become "double trapped".

TonyS

Interesting Ice

so you trap after the interceptor? I haven't been doing much commercial plumbing since I was a journeyman doing the school asbestos rebuilds in the late 80s early 90s. At that time we were using BOCA and International. At that time grease interceptors would suffice as the sink trap as long as the vent to weir distances were maintained, also foul waste limit was 24 inches. We would install the flow limiter, usually supplied with the grease interceptor and use a local vent that terminated high behind the sink.( although I had seen a few that the plumber tied back into the vent stack which was an obvious cross connection between the vent stack and the drain on the fixture side of the trap.

For the last 20 some years I have concentrated on heating and air but have maintained my plumbing skills by doing a few waste pipe replacements.

I still have my grandfathers starbuck books  from the early part of last century and had always assumed that the laws of physics and plumbing are constant LOL. What was I thinking!! It seems the grease interceptors havent changed but there are many opinions on how to pipe them. I definitely need a new code book and a little time to read it.

Thanks for your input

Robert O'Connor_12

TonyS

No trap is required after the interceptor.

 Fixtures that discharge into a hydro-mechanical or GRD grease interceptor must be trapped and vented between the fixture and the interceptor except for when the required flow control device is installed, and only for an individual fixture and its developed length doesn't exceed 30" vertically, then it can be installed without the addition of a trap.

Those old Starbuck books are the best. I still have a few and will never get rid of them.

@Charlie, maybe the AHJ is still reading those old books lol. It is always challenged when I propose these installs but considering the saving when you are installing 50 or more on a single job. It all adds up. I'd much rather challenge the AHJ and in the end put a bucket full-0-money in me pocket and educate at the same time...;)



Robert O'Connor/NJ

icesailor

Grease Interceptors/recovery:

I mis-wrote.

MA, or where I work, we always used the "Grease Trap" as a "Trap". The interceptor was the trap.

In my 2009/20010, CEU, we were given diagrams of a change where the interceptor was no longer the trap. I haven't installed one since the change. The health department was making restaurants make the changes. The few places I had them were not forced to change then and still have not.

I just got my book for the change and it shows the "obsolete" drawing, and the "Official Revision". It shows a trap, and vent before external flow control and the vent for the flow control connected to the waste vent tied into the sanitary vent. With no trap between the outlet of the interceptor and the sanitary waste.

The MA PHCC CEU classes are the best because they give you a nice big book on everything discussed in the classes and a frameable certificate. And nice big drawings on how it was and how it is now to be done.

Sorry for the mis-information.