Confined-Space Entry for Grease Interceptors

A grease interceptor is a buried tank with a small opening, no place to stand and no design for people to occupy it. That fits OSHA's definition of a confined space. It becomes permit-required if it contains, or may contain, a hazardous atmosphere or has another serious hazard. A tank of kitchen wastewater and grease is a place where gas can build up, which is the situation that rule was written for.

The standard also splits work into general industry (29 CFR 1910.146) and construction (Subpart AA, starting at 1926.1201). The two track each other closely, and which one applies to a given job depends on whether it is maintenance or construction work. Both require the same core: find out what the space holds, control it, keep someone outside, and be able to get the person out. For the private manhole version of this question, see private sewer manhole and wet well entry.

OSHA calls hydrogen sulfide sewer gas. It is heavier than air, so it pools in low and enclosed spaces like manholes, sewers and underground vaults. At low levels it smells like rotten eggs. At higher levels, OSHA's table shows the smell disappears: loss of smell, called olfactory fatigue, shows up around 100 to 150 ppm. That is why "I don't smell anything" is not a safety test. OSHA's general industry ceiling is 20 ppm, and at several hundred ppm collapse can come within minutes.

The standard does not name grease tanks specifically. It names the hazard, and it tells the employer to test the space for it. So we test, and we do not assume. See hydrogen sulfide detectors for buildings for the building side.

HQ repairs and inspects grease interceptors. HQ does not pump them. A licensed hauler empties the tank first, and then our crew of three arrives.

• Air is tested first, in OSHA's order: oxygen, then flammable gas, then toxic gas.
• Fresh air is moved in with intake equipment, so the person inside is not breathing what the tank holds.
• A tripod and harness lower the entrant and give the crew a way to pull the person out without anyone else going in. OSHA's rule calls for this kind of retrieval system.
• One person stays outside for the whole entry, watching the entrant and ready to start the rescue plan.
• A third person supports the work, so the attendant and the entrant are not also running the equipment.

That is slower than a ladder and a flashlight. It is the correct way to do it. Our crew's approach is the reason a repair visit is a three-person job, as described on the grease interceptor repair page.

You are the host employer. OSHA's host rules mean you tell the contractor what you know about the tank, and they tell you how they will enter. Ask these before anyone opens a lid.

1. 1Do you have a written confined-space program and an entry permit for this tank?
2. 2What will you test, in what order, and with what meter? The right answer is oxygen, flammables, toxics.
3. 3Who is the attendant, and will that person stay outside the whole time?
4. 4How will you get an injured person out? Look for a harness, a retrieval line and a tripod or other mechanical device.
5. 5Who is trained, and can you show the training certification? OSHA requires employers to certify training.
6. 6Will you tell me what you found when you finish?

If the answer to the second or fourth question is a ladder and a hope, that is a no. Keep the answers with your records, along with what the tank repair found. Phoenix, Mesa and Chandler all expect repairs to be logged, and the permit and findings are part of that paper trail.

Not every grease problem needs anyone inside. If the tank is simply full, the pumper handles it from the surface. If the question is whether grease is leaving the tank, a camera pass downstream of it can answer that without entry. See restaurant grease line jetting. And do not let staff climb in to check a part. Even a shallow tank can hold air that cannot support a person.

Tell us the city, the tank size and the reason for the visit. We can plan around the pumper, as described in pump-out and repair coordination. We offer 24/7 emergency service, free estimates and an upfront price before work starts. Related: grease trap and interceptor service, restaurant plumbing and commercial plumbing.