Secondary Containment requirements for Wastewater Tank 2

[Bagman2524]

Is anyone aware of any worker safety requirements while in a wastewater tank secondary containment area? I have a 150 ft dia x 40 ft high tank that will hold mitigated Alky water. We are looking at a secondary containment wall around the tank. NFPA-30 limits walls to 6 ft high unless other arrangements such as stairs, platforms, etc. are made for workers within the secondary containment for the workers to get to higher elevation. However, NFPA-30 is for flammable or combustible tanks. Does a similar requirement apply for tanks containing hazardous wastewater?

 

[bimr]

If you waste is actually determined to be and defined as being wastewater, then there are no secondary containment requirements.

Secondary containment does not have to be equivalent to the design standards of the primary tank. Secondary containment design standards only have to be good enough to be able to hold the material until the spilled material is cleaned up.

There are no worker safety requirements for working within a secondary containment area that are specifically identified by the regulations that call for secondary containment.

 

[CarlB]

I had understood the NFPA 6' limit had to do with firefighting access purposes, not day-to-day workers.

 

[greenone]

Are you asking if sec containment is necessary for ww tanks, or are you asking what safety precautions are necessary for workers inside an existing sewc containment area?

 

[Bagman2524]

both, but I'm a bit more interested in the safety issue.

 

[zelgar]

In general, for RCRA (Hazardous waste) tanks, the secondary containment requirements are the following:

Volume - 100% of the largest tank + the volume of the 25 yr 24 hr storm event (note: when calculating precipitation volume make certain you use the area of the containment system x the inches of rain for the storm).

Additionally, the material of construction for the secondary containment needs to be compatible with the wastes. Typically, you'll see a concrete vault with PVC waterstops at the joints and a coating (epoxy is common).

 

[StoneCold]

We require air monitoring in any pit or containment area that has the potential of a dangerous atmosphere. You can never over test. No one has been killed by over testing the atmosphere for breatability or flamability.
I personally would not make the containment wall higher than four feet if I could help it. Four feet high, almost anyone can dive over and come out of a bad situation ok. Six feet is considerably harder to get over without some form of help.

 

[bimr]

Regarding "NFPA-30 limits walls to 6 ft high unless other arrangements such as stairs, platforms, etc. are made for workers within the secondary containment for the workers to get to higher elevation"

Here is the OSHA Standard that defines the OSHA requirement for stairs.

Stairs and railings shall meet OSHA Standard 29 CFR Ch. XVII, paragraph 2910.24.

http://www.access.gpo.gov/nara/cfr/waisidx_05/29cfr1910_05.html

The OSHA requirements should be considered as the minimum. For practical purposed, you probably should include a crossover if the containment wall is higher than 18"

Here is a useful link for most of the technical documents:

http://epa.gov/OEM/docs/chem/pennzoil.pdf