What is an automatic grease removal device (AGRD)?

An automatic grease removal device, called an AGRD or a GRD, is a plumbing device that pulls free-floating grease out of kitchen wastewater without a person skimming it.

Phoenix's amended definition says such a device operates on a time-controlled or event-controlled basis and can remove free-floating fats, oils and grease automatically, without intervention from the user except for maintenance. The Plumbing and Drainage Institute, a trade body, describes the same thing. A grease interceptor holds the grease. The GRD then moves it to an outside collection container.

### What is inside one?

A fact sheet from Delta Diablo, a California sewer district, describes the typical unit. It is a type of hydromechanical grease interceptor with automatic removal features. It is usually installed indoors and connected to one to four kitchen sinks. Its diagram shows an inlet, a flow control device, baffles, a skimmer, a heating element and a removable solids basket. The fat it collects goes into a separate waste container. The sheet gives typical sizes of 15 to 60 gallons and 20 to 50 gpm.

That is a small footprint compared to a buried tank.

### How is it different from a gravity interceptor?

• Size. A gravity interceptor is a large tank, at least 500 gallons in Phoenix. A GRD is a small unit at the sink.
• Power. Delta Diablo's fact sheet says some GRDs have heaters, skimmers or pumps. A gravity tank is a passive device.
• Daily work. Delta Diablo's fact sheet says a GRD should be maintained by emptying the solids basket into the trash daily and emptying the FOG container daily, and that the mechanical equipment must be maintained by the food service establishment.
• Where it works. Wichita, Kansas says these devices cannot handle the same volume of water as an underground grease interceptor and are not a viable solution for many food service establishments.

For the trap-versus-tank basics, see grease trap vs grease interceptor.

The 2024 International Plumbing Code treats an AGRD as an alternative to a grease interceptor for the fixtures that make grease.

### Section 1003.3.1

A grease interceptor or automatic grease removal device is required to receive the drainage from fixtures and equipment with grease-laden waste in food preparation areas, such as restaurants, hotel kitchens, hospitals, school kitchens, bars, factory cafeterias and clubs. These devices receive waste only from fixtures and equipment that allow fats, oils or grease to be discharged.

### Section 1003.3.6

Where an AGRD is installed, the code says it shall be:

• Located downstream of each fixture or group of fixtures, in accordance with the manufacturer's instructions.
• Sized to pretreat the measured or calculated flows for all connected fixtures or equipment.
• Given ready access for inspection and maintenance.

### Section 1003.3.5

AGRDs are tied to test standards. The code says they shall be designed and tested in accordance with ASME A112.14.3, ASME A112.14.4, CSA B481.1, PDI G101 or PDI G102, and installed per the manufacturer's instructions. The PDI page names ASME A112.14.4 as the standard for grease interceptors equipped with automatic grease removal devices, with testing requirements and performance criteria.

Delta Diablo's fact sheet adds that sewer agencies often require a GRD to be certified to those standards before approval. A city's approved list is where that shows up.

### What the base code does not settle

The model code sets the general rule. Each city adopts it, then amends it. Phoenix's amendment to Section 1003.2 says its City Code 28-13 gives approval authority for all interceptors to the Director of Water Services. This is one reason the answer to the question in the title changes from town to town.

Short version: Phoenix does not allow one alone. Scottsdale's guidelines still list it. The other Valley pages we read say nothing about it.

### Phoenix

Phoenix amended the code. In its Section 1003.3.1 amendment, the city's justification says AGRDs are not allowed as a standalone device by the City of Phoenix Water Department's Office of Environmental Programs. The amended Section 1003.3.1 removes automatic grease removal devices from its required-device wording, so the section now speaks only of grease interceptors. The standalone limit is stated in the city's justification for the change, not in the amended code text. Phoenix's Section 1003.3.5 amendment still names AGRDs for sizing and testing.

The city's definition change explains the reason. The definition adds that these devices must be able to perform as a gravity interceptor if mechanical or electrical power is lost, and provide continuous separation. The justification says some grease removal devices rely on moving parts and electricity to separate grease from the waste stream, and that the amendment requires the device to still work as a passive device if moving parts break down or power is lost.

Phoenix also amends the same section to say that commercial dishwashers and food waste disposal units shall discharge to a gravity grease interceptor. So even before the AGRD question, a Phoenix kitchen with a dishwasher needs the tank. The Phoenix trap versus interceptor page gives the fixture-count rule.

What Phoenix does not say in the documents we read is whether an AGRD may be added next to a gravity interceptor. Do not assume either way. Ask Environmental Services.

### Scottsdale

Scottsdale's grease interceptor guidelines, based on its amended 2021 IPC and last modified January 2023, reproduce the section headed grease interceptors and automatic grease removal devices required. They also list the AGRD section on location downstream of fixtures, sizing to pretreat the connected flows, and ready access. The guidelines' introduction says grease interceptors and Grease Removal Devices are the best options for keeping the sewer system operating properly.

The guidelines' trap sizing section covers hydromechanical interceptors. It allows them only with four or fewer food preparation fixtures and says any facility installing a dishwasher shall install a gravity grease interceptor. It does not mention AGRDs there, so how it applies to one is a question for the city.

### Mesa, Chandler, Tempe and Surprise

We did not find an AGRD rule on these cities' pages:

• Mesa City Code 8-4-22
• Chandler's Food Service Establishments page
• Tempe's FOG Program page
• Surprise's Commercial Pretreatment page

Silence is not approval. These pages tell you how to size and place traps and interceptors. They do not say a device like this is acceptable in their place. Ask the pretreatment office before you order anything.

### Another city's approach

Wichita, Kansas is an example of a city that allows them only by exception. Its page says AGRDs are allowed only after an approved variance letter from its FOG program. It also requires a maintenance log to be submitted each quarter and kept in the establishment. That is not a Valley rule. It shows how a city can treat the device.

Get answers before you spend anything, because a device the city will not accept has to come back out.

1. 1Is an AGRD accepted in my city, alone or with an interceptor? Ask for the answer in writing.
2. 2Is the model on an approved list? Ask whether it must be certified to ASME A112.14.3 and A112.14.4, or a PDI standard.
3. 3How many fixtures can it serve? The code says sizing must cover the connected flows. Ask which fixtures the city will let you connect.
4. 4What is the daily routine? The fact sheet describes daily emptying of the solids basket and FOG container. Ask who on your staff will do it and when.
5. 5What happens if the power goes out? Phoenix wrote its amendment around this exact point.
6. 6Do dishwashers and disposals route around it? In Phoenix they must go to a gravity interceptor.
7. 7Is the location reachable? The code calls for ready access for inspection and maintenance.

Also keep the maintenance records. Chandler and Phoenix both expect records on site for 3 years for grease devices, so plan a log from day one. See our maintenance log page.

### Can enzymes or additives do the same job?

No. Phoenix's manual prohibits using chemicals, enzymes, proteins, bacteria, grease solvents or emulsifiers to temporarily dissolve fats, oils and grease. See are enzyme drain treatments allowed and what can go down a restaurant grease trap.

Call before you buy. A licensed and insured plumber can count your grease-bearing fixtures, tell you which route your city is likely to accept, and prepare the plan the city will want. If the answer is a gravity tank, see installation steps, the sizing worksheet and the permit page for adding or replacing an interceptor.

HQ Plumbing and Air handles commercial plumbing, gives free estimates, and states upfront pricing before work starts. For a kitchen that is backing up, we offer 24/7 emergency service. See our commercial plumbing page.