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Johnson County, Kansas Environmental Department Protecting You and Your Environment |
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Sizing of Grease Interceptors
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Grease interceptor sizing is based on providing a 30 minute peak hydraulic detention time, calculated on plumbing fixture units. The following table is used to size grease interceptors in the Wastewater Districts service area:
All kitchen drains must be plumbed to the grease interceptor. When using the above chart only use sinks and dish machines. 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 thirty- minute detention time. Example: If you had a 2 inch drain going to a grease interceptor from a 3-compartment sink and a 2 ½ inch drain from a dish machine going to the grease interceptor, the calculation is as follows: 22.5 gpm x 30 minute detention time = 675 gallons for the 3 compartment sink. 30 gpm x 30 minute detention time = 900 gallons x 0.3 factor = 300 gallons for the dish machine. This would round up to 1000 gallons. The minimum size for a grease interceptor is 1000 gallons. The maximum size for a grease interceptor is 2000 gallons. If a larger capacity is needed, grease interceptors shall be connected in series. |
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