Environmental Protection Agency Method:

As published in the EPA Design Manual – Onsite Wastewater Treatment & Disposal Systems, the recommended method for sizing a grease interceptor is as follows:


1. Restaurants


(D) x (GL) x (ST) x (HR/2) x (LF) = Size of Grease Interceptor (gallons)


Where:


D=Number of seats in dining area
GL=Gallons of wastewater per meal, normally 5 gallons
ST=Storage capacity factor, min. of 1.7 for onsite disposal, 2.5
HR=

Number of hours open

LF=Loading Factor:
2.25 Interstate Freeways
1.0 Other Freeways
1.0 Recreational Areas
0.8 Main Highways
0.5 Other Highways

2. Hospitals, Nursing Homes, other type Commercial Kitchens with varied seating capacity


(M) x (GL) x (ST) x (2.5) x (LF) = Size of Grease Interceptor (gallons)^3

Where:


M=Meals per day
GL=Gallons of wastewater per meal, normally 4.5 gallons
ST=Storage capacity factor, min. of 1.7 for onsite disposal, 2.5
LT=

Loading Factor:
1.25 Garbage disposal & dishwasher
1.0 Without Garbage disposal
1.0 Without dishwashing
0.8 Without dishwashing & garbage disposal

a=Without dishwashing & garbage disposal

Grease Traps



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Sizing of Grease Interceptors


The grease interceptor is generally sized according to the local plumbing code. The different variables include: number of meals per hour of seats, wastewater flow rate, wastewater detention line, storage factor, and detention time.


Uniform Plumbing Code Method:

As recommended by the Uniform Plumbing Code – Appendix H, the following sizing method is as follows:


Uniform Plumbing Code Sizing Method
1. Restaurants


(D) x (MF) x (GL) x (RT) x (ST) = Size of Grease Interceptor (gallons)


Where:


D=Total number of seats
MF=Metal factor, based on establishment type & average time per meal:
1.33 Fast Food/Cafeteria (45 min)
1.00 Restaurant (60 min)
0.67 Leisure Dining (90 min)
0.50 Dinner Club (120 min)
GL=Gallons of wastewater per meal:
6 With dishwashing machine
5 Without dishwashing machine
2 Single service kitchen
1 Food Waste Disposal
RT=

Retention Time:

2.5 Commercial kitchen waste
1.5 Single service kitchen

ST=Storage factor, based on hours of operation:
1.0 Operation of 8 hours
1.5 Operation of 12 hours
2.0 Operation of 16 hours
3.0 Operation of 24 hours
1.5 Single service kitchen

Fig. 3 - Typical Grease Interceptor Installation

For larger sizes and other commercial or industrial applications, contact our engineering department

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