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The Failures You Cannot See From the Lid

A vessel that is pumped on schedule and looks normal can be passing grease straight through, and there is usually a specific reason.

The short form

A vessel pumped on schedule can still pass grease. The usual causes are a missing inlet tee, a broken baffle, a garbage disposal or dish machine plumbed into it, and a vessel sized wrongly in either direction. None of those are visible from the lid.

Source: U.S. EPA, FOG Management and Control Program.

InterceptorCall is a referral service, not a contractor. We connect operators and property managers with independent contractors. Contractors and waste haulers are required to hold whatever credential and permit their state or municipality demands — ask to see them, because the manifest they leave you is a compliance record. We carry out no work, we haul nothing, we do not set prices, and we never charge the caller anything. Nothing here states the grease limit, the pumping interval or the device size that applies to any particular kitchen; those are set by your control authority and by your installation.

No inlet tee

The inlet is supposed to carry incoming flow down below the surface. Without that, flow arrives at the top and lands in the floating layer, which both disturbs it and pushes it toward the outlet.

EPA’s material is blunt about this: no inlet tee is a problem, because the layer blocks flow and there is no retention time. It is also one of the few defects that can be seen from the lid if you know to look.

Source: U.S. EPA, FOG Management and Control Program.

The wrong things plumbed into it

A dish machine is the classic one and it has its own page here because the mechanism is worth understanding rather than memorizing. A pre-rinse sink is fine; the machine itself is not.

Garbage disposals are the other frequent culprit, because they send solids into a vessel whose settled layer then grows far faster than anybody planned for.

Materials and fittings that fail quietly

EPA’s material sets a floor of Schedule 40 PVC for outlet tees and notes that lighter plastic baffle attachments fail. A broken baffle does not announce itself — the vessel keeps filling and keeps getting pumped, and the separation stops happening.

Two-piece vessels are also called out against monolithic ones, because a seam in the ground is a leak waiting for its moment.

And the one that is upstream of everything

A vessel that is right in every respect can still fail because of what is happening in the kitchen before the drain. Scraping, dry-wiping pans and keeping fryer oil out of the sink are not decorations on a program — they are the least costly control available and the only one that reduces the load rather than catching it.

They are also what an inspector will ask about, because they are what distinguishes a kitchen that is managing grease from one that is storing it.

What not to put in it

Additives that claim to dissolve, digest or emulsify grease deserve a hard look and a question to your control authority before anything goes in the vessel. Emulsified grease is grease that leaves the device and solidifies further down the sewer, which is precisely what the prohibition is about.

Some authorities prohibit them outright. We are not going to tell you yours does or does not — we are telling you it is a question with a real answer and a real consequence.

Source: 40 CFR 403.5, National pretreatment standards: Prohibited discharges.

Have the last manifest in front of you.Date, hauler, volume removed and where it went — it is the first thing anyone asks for and it tells a contractor more about the state of the vessel than a description does. We will route you to somebody who covers your area, identified from the ZIP code of the premises, and you are never charged. Other plumbing work at the premises can be arranged through the same call.

Call (888) 753-1770