Containment wall causing confined space

BamaStrucPESE · May 18, 2015

Working on a project where the client is wanting to place a tank inside an existing containment area with ~42" walls. The slab in the containment area slopes towards a sump, so the wall is 3'5" on the short side and 4'2 on the tall side. We may need to raise the wall height a few inches to maintain containment volume and I was wondering at what point would the area be considered a confined space. I know if the wall is over 4', then it is confined space, but is that 4' all over, 4' average or 4' at the highest point, in which case it would already be a confined space?

JedClampett · May 18, 2015

A confined space is defined as a portion of a building or structure:

Is large enough for an employee to enter fully and perform assigned work

has a limited or restricted means of entry or exit

is not designed for continuous employee occupancy

So technically, if the wall restricts entry or exit (which it will), the containment is a confined space. You're probably worried that it's a permit required confined space, which is all of the above, plus an potential hazard.

JStephen · May 18, 2015

Put a stairway down into it?

SlideRuleEra · May 19, 2015

BamaStruPE said:
...at what point would the area be considered a confined space. I know if the wall is over 4', then it is confined space, but is that 4' all over, 4' average or 4' at the highest point, in which case it would already be a confined space?

IMHO, this will be a judgment question that can really be answered only by OSHA. However, there is one really important question that could sway the answer:

What are the contents of the tank?

Say, a best case answer might be "potable water". Then there may be reasonable room for differences of opinion and negotiations with OSHA.

Perhaps a worst case could be something like "sulfuric acid". Then, the existing containment probably should already be a confined space.

Of course there are other tank contents that make the decision more of an administrative decision than a technical one.

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