# Individual drains or Trench Drain



## Mech (Aug 30, 2017)

2009 IPC

S-1 Automotive Repair Garage

The proposed repair garage has 6 floor drains, each spaced 16 feet apart.  I connected 6 individual drains, without traps, to a common branch and showed one trap and vent on the common branch right before it exits the building.  (The oil water separator is outside.)  There are no other fixtures on this branch.  The code official said that all floor drains need to be trapped and vented appropriately.  Yes, that is correct per 1002.1 and none of the exceptions apply.

Why can I not install these floor drains as originally designed and consider them a single 80 ft long trench drain with alternating solid and open grated covers?


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## north star (Aug 30, 2017)

*+ + + +*

Mech,

I have looked & looked for "an out" for your application,
but have not found anything, ...yet !

Do you just "have to have" the 6 individual floor drains,
or can you install one trench drain near the bldg. exit
point, and make that work in your application ?

Why the 6 individual Floor Drains spaced 16 ft. apart ?

Thanks !

*+ + + +*


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## Mech (Aug 31, 2017)

North Star,

Thanks for looking.

The garage is 85 feet long, with the drains to catch dripping water and melting snow that falls off the cars.

Another engineer in my office agreed with the original 6 inlet trench drain theory with one trap and vent.  But to keep the reviewer happy and get the permit, I revised the design to provide a combination drain and vent system in accordance with Section 912.


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## Francis Vineyard (Aug 31, 2017)

IMO he's over thinking the term floor drain as connected to the building sanitary or sewer and neglecting the purpose of a trap; to prevent sewer gases releasing into the atmosphere.

Additionally the 2015 clarified that oil separators are not required; though I'm aware some jurisdictions may specify that they be installed.

As former mechanic we hated floor and trench drains having to retrieve dropped parts through the muck, clogging and stinking up the place.

*2015 Code: 1003.4 Oil Separators Required*. At repair garages where floor or trench drains are provided, car washing facilities, at factories where oily and flammable liquid wastes are produced and in hydraulic elevator pits, oil separators shall be installed into which all oil-bearing, grease-bearing or flammable wastes shall be discharged before emptying into the building drainage system or other point of disposal.
*Exception:* An oil separator is not required in hydraulic elevator pits where an approved alarm system is installed. Such alarm systems shall not terminate the operation of pumps utilized to maintain emergency operation of the elevator by firefighters.
*CHANGE SIGNIFICANCE:* The main section language has been frequently misinterpreted as requiring repair garages to have floor or trench drains so that required oil separators could be connected to the drains. This section never intended to require floor or trench drains in repair garages. In fact, many repair garages do not have drains as some believe it is safer to use dry absorbent compounds to soak up spills rather than to have oily residues build up in drain systems. The 2015 IPC makes the requirement clear.


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## north star (Aug 31, 2017)

*+ + +*

Mech,

Can you revise what has already been installed
[  meaning, to remove & re-plumb  ] to utilize
one (1x) trench drain only, or no floor drains at
all ?.......Spills & liquids can be moved by
squeegees, and captured with a variety of
absorption methods and materials [ i.e. - Wet
Vacs, poly-absorbent waddles, absorbent pig
towels, pads, mats, etc. ]

Mech,

What you have are extensions of a Trench Drain,
not a true Floor Drain with trap seals.

You mentioned that the drains are to capture
"dripping water and melting snow that falls off
of the cars".......Will there actually be any vehicle
repairs in this Garage, or is it more of for storage ?
FWIW, ...the 2009 IPC doesn't leave much wiggle
room for Exceptions.

Francis, I agree that the AHJ is not seeing the
intent of these floor drains, for the Letter of the
Code getting in the way.

*= = =*


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## Mech (Sep 14, 2017)

north star,

Nothing has been installed yet.  The drawings are almost ready to be sent for review again.  The contractor can let us know if they can install a trench drain cheaper than individual drains.

The portion of the building with the drains is the actual repair areas where cars will be serviced.

We can always revisit this and debate it with the code reviewer after we start construction.

Thanks guys!!!!


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## JavierCoats (Oct 17, 2017)

It's quite necessary to learn more about this situation. I will be checking out this resource. I think that it's pretty vital for many people to browse this forum.


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## HForester (Oct 28, 2017)

IMHO, a trench drain is a fixture. Every fixture is required to have a trap. If the trench drain is one looonnnggg  trench drain, it is one fixture and only one trap is needed. Except for certain specific applications (see the first section of IPC Chapter 10), hooking the waste outlets of individual fixtures together and then having one trap to serve all of that, just isn't what the code wants us to do.


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