Grease Trap Tank Fact Sheet
This guidance document is advisory in nature but is binding on an agency until amended by such agency. A guidance document does not include internal procedural documents that only affect the internal operations of the agency and does not impose additional requirements or penalties on regulated parties or include confidential information or rules and regulations made in accordance with the Administrative Procedure Act. If you believe that this guidance document imposes additional requirements or penalties on regulated parties, you may request a review of the document.

Form #:  12-027
Guidance Documents
Revised: 11/22/16


Grease trap tanks or grease interceptors are designed for the collection and periodic removal of fats, oils, and grease. A grease trap tank or interceptor used in an onsite wastewater treatment system must be water tight and constructed of materials not subject to excessive corrosion or decay. Acceptable tank construction materials are concrete, fiber reinforced plastic, high density plastic and fiberglass.

Design

A restaurant or non-dwelling facility involved in food preparation must have a separate wastewater line to a grease trap tank for the food preparation and dishwashing wastes. All wastewater from the kitchen operation must be discharged to the external grease trap tank. Wastewater lines for graywater and non-kitchen blackwater including restroom and toilet wastes cannot be connected to the grease trap tank.

The inlet invert of a grease trap tank must be at least three inches above the outlet invert. In addition, the grease trap tank must be provided with an inspection or clean out cover over the inlet and outlet. The effluent from the grease trap tank must connect to the inlet line of the septic tank.

Capacity

A grease trap tank must provide twenty four hours of detention time for the average daily flow. The minimum capacity of any grease trap tank must be 750 gallons.

Placement

A grease trap tank must be located ahead of the septic tank. An existing restaurant or non-dwelling facility involved in food preparation that is replacing or modifying its onsite wastewater treatment system may install an additional septic tank in the waste line in lieu of a grease trap tank provided: the restaurant or non-dwelling facility was constructed before the effective date of the regulations; the current kitchen and blackwater waste streams are not separated; the additional septic tank is sized in accordance with Title124; and the additional tank is placed in series with other tanks and all tanks comply with all other applicable Title 124 requirements.