Requirements For Commercial Facilities
Grease interceptors are required in following commercial facilities:
- Restaurants- All types, Fast food. Pizza delivery, Sandwich shop, Bakeries.
Learn about Best Practices for Fats, Oils and Greases
- Services Stations- Auto repair, Car washes, Fuel Stations
- Pet Grooming, Salons- Hair traps
- Laundries- Lint/Hair traps
- All photo processing facilities, dental offices, and x-ray processing facilities shall be equipped with a metal recovery unit
Do you need to install a Grease Interceptor?
Types of fixtures that require a grease trap / interceptor
- 3 - compartment sink
- pre-rinse sink
- mop/floor sink
- dishwasher machine floor drain
- wash stations
- flow through and floor drains with grease laden potential
Types of fixtures that do not require a grease trap or interceptor
- hand sinks
- ice machines
- bathroom floor drains
- water fountains
- soda machine drainage
Do not discharge the following fixtures to grease trap or interceptor
- Restroom facilities such as toilets Urinals and other similar sanitary fixtures
- Hot liquids
Grease interceptors within the city shall be:
- outside installation
- accessible for cleaning and inspections
- minimum of 750 gallons and a maximum of 2500 gallons
- installed and maintained per the manufacturers specifications
- appropriate traffic rated covers
*The type of food served and preparation methods employed shall be taken into consideration.
What size Grease Interceptor should be installed?
| Fixture Outlet or Trap Size
|Drainage Fixture Unit Value
|| GPM Equivalent
| 1 1/4
|Floor Drains - All
||2x Trap Arm Size
- Determine total Fixture- Unit Value by multiplying fixture type count by the drainage value.
- Total all values.
- Determine total flow by multiplying total value by flow rate of 3 GPM.
- Multiply total flow by 12 if no garbage disposal unit is used.
- Multiply total flow by 17 if garbage disposal unit is used.
- Round to the next nearest size interceptor – (minimum 500 gallons not to exceed 2500 gallons)
| Type of Fixture
|| Fixture Count
||Size|| Fixture-Unit Value
|3 comp sink
|Total Fixture units
|Multiply by 3 GMP Flow Rate
|Total GMP Flow Rate
|Multiply by either 12 or 17
without or with garbage disposal unit
|Size of Interceptor calculated
|Round up to next available size
City of Surprise Guidance for Grease Interceptors
Large interceptors cause long-term issues where odor and gases build up in the sewer and become exposure issues for crews lifting manhole covers located downstream of large interceptors. These gases can pose an immediate danger to health and life (IDHL).
Interceptors Shall Be:
- 750 gals or larger for 3 compartment interceptor
- Installed according to manufacturers specifications. Appropriate rated covers
- No more than 2 restaurants per interceptor with under sink trap units installed
- Two smaller interceptors are required once the size reaches over 2500 gallons
Grease Trap in Lieu of Grease Interceptor
The following are examples of those facilities that may install a grease trap in lieu of a grease interceptor with appropriate calculations performed, submitted and sealed by a State of Arizona Certified Professional Engineer
- Sandwich shops
- Coffee shops
- Pizzas take out and bake with no inside service pizza only and no fryers
- Ice Cream shops (ice cream or yogurt may not be made on premises and all ware must be disposable)
*These facilities must not have a type one hood instillation.
Oil & Sand Interceptors
Oil and sand Interceptors are designed to separate oily waste from interior drainage systems, or exterior run-off areas. Commonly specified in service stations and other vehicle maintenance, car washes and parking areas, oil and sand interceptors prevent environmentally damaging and potentially dangerous oily substances from entering, run-off areas, and POTWs.
Similar to grease interceptors in operation, oil and sand interceptors accumulate lighter-than-water oily and heavier that water solid waste, above the static water line and at bottom inside the interceptor. Oil can be automatically drained from the interceptor through a draw-off valve, and directed to an approved holding tank (by others), for storage and eventual removal. Solids are collected at the bottom of the interceptor and have to removed (by others).
Material & Characteristics
Interceptor body - shall be constructed of impervious materials capable of withstand abrupt and extreme changes in temperature. They shall be of substantial construction, watertight and gastight equipped with easily removable lids.
Flow Restrictor - Oil interceptors shall be supplied with a built-in stainless steel flow restrictor plate, just inside the inlet.
Oil and sand Interceptors are sized according to the rate of incoming flow, in gallons per minute (GPM).
Flow rate can be calculated by adding the maximum discharge rates of all potential water sources. For example, a standard 3/411 hose connection will discharge approx . 10 GPM. A service garage with three hose connections would have a maximum potential flow rate of 10 GPM x 3, or 30 GPM. Plus the addition of floor sinks and any drainage system damaging and potentially dangerous oily substances.
For outdoor applications involving rainwater run-off, flow rate should be derived from local rainfall tables, and the slope characteristics of the area to be drained.