The following are requirements for new grease interceptors installed at food service facilities:
- The grease interceptor must be of sufficient size to provide a 30 minute detention of the peak wastewater flow. The minimum size for a grease interceptor is 1,000 gallons. The maximum size is 2,000 gallons. The interceptor location must allow for pumping and inspection access. Indoor grease interceptors or grease traps are not permitted in new facilities.
- An engineer shall submit grease interceptor sizing calculations on plans and indicate sizing method used (see Interceptor Sizing information below).
- The vent line from the sample port riser on the interceptor outlet must be connected to the building waste vent piping.
- Grease Waste Fixtures:
- Garbage disposals or grinders are prohibited in new food service facilities.
- The following plumbing fixtures (if applicable) MUST NOT be connected to a grease interceptor:
- Handwashing sinks
- Drains receiving condensate only
- Bar sinks not receiving significant quantities of grease
- The following plumbing fixtures (if applicable) MUST be connected to a grease interceptor:
- Low temperature chemical (e.g., chlorine) sanitizing dishwasher
- High temperature (greater than or equal to 180°F) sanitizing dishwashers which must have a cold water solenoid-operated valve or similar device that mixes cold water with the discharged hot water from the machine
- Three (3) compartment sinks
- Mop sinks
- Floor drains in kitchen areas
- Wok drains
A grease interceptor must provide a 30 minute peak hydraulic detention time as determined by the plumbing fixtures or piping connected to the interceptor. The following table is used to size grease interceptors in the Johnson County Wastewater sanitary sewer service area:
All kitchen drains must be plumbed to the grease interceptor. When using the table above, only use sinks and dish machines in the calculation. Floor drains and mop sinks do not produce a sufficient quantity of water to be added to the calculation, but must be plumbed to the interceptor.
For dish machines, multiply the result by a factor of 0.3 to compensate for the time that the machine is not discharging wastewater.
The interceptor is sized using the drainage gallons per minute multiplied by a 30 minute detention time.
Example: For a two (2) inch drain discharging to a grease interceptor from a three (3) compartment sink and a 2.5 inch drain from a dish machine discharging to the grease interceptor, the calculation is as follows:
22.5 gpm x 30 minute detention time = 675 gallons for the three (3) compartment sink
30 gpm x 30 minute detention time = 900 gallons x 0.3 factor = 300 gallons for the dish machine
675 gallons + 300 gallons = 975 gallons for the interceptor. Round up to 1,000 gallons
The pipe diameter after the last grease waste fixture is used to determine the size of the grease interceptor. Pipe shall be installed at one (1) percent slope maximum. Pipe slope shall be indicated on interior plumbing drawings.
Example: For a 4 inch line downstream from the three (3) compartment sink and the dish machine discharging to the grease interceptor, the calculation is as follows:
45 gpm x 30 minute detention time = 1,350 gallons for the interceptor. Round up to 1,500 gallons.
The minimum size for a grease interceptor is 1,000 gallons and 2,000 gallons is the maximum size.
If a larger capacity is needed, grease interceptors shall be connected in series and must be approved by Johnson County Wastewater.
Please modify the detail to reflect the required volume and piping arrangement for the project.
- Interior Piping
- Johnson County Wastewater shall inspect the interior plumbing fixtures that are attached to the interceptor before the plumbing is covered. Please call Johnson County Wastewater's Permit Group at 913-715-8520 to schedule an inspection of the interior plumbing before the piping is covered.
- Johnson County Wastewater shall inspect the installed interceptor and exterior piping prior to backfilling and after inspection of the interior piping. Please call Johnson County Wastewater's Permit Group at 913-715-8520 to schedule an inspection.
Prior to discharging wastewater to a grease interceptor, a food service facility shall obtain their grease interceptor operating permit from Johnson County Wastewater. This permit will be issued after all construction is complete and Johnson County Wastewater has determined that the interceptor and facility complies with the Johnson County Code of Resolutions:
Please call Johnson County Wastewater's Environmental Compliance Manager at 913-715-6920 two (2) weeks prior to opening to schedule a site visit which is required for permit issuance.
All food service facilities in the State of Kansas MUST also obtain a food service license from the Kansas Department of Agriculture (KDA) at 785-296-5600 before opening.