Oil and Grease Program

Grease can cause sewer backups that create environmental hazards and major inconveniences for our customers and the city. Grease also is more difficult and expensive to treat at the wastewater treatment plants. The goal of the city oil and grease program is to lower maintenance costs and keep the sewer system operating smoothly.

An overview
Grease in a warm liquid form may not appear harmful. But, as the liquid cools, the grease congeals causing buildups that result in backups of sewer lines. Pipe cleaning companies report that 95% of the problems they fix are due to grease. Problems caused by grease producing establishments have forced regulations on the discharge of grease to the sewer system. These regulations include the installation of preliminary treatment facilities known as grease interceptors.

What is a grease interceptor?
A grease interceptor is a concrete structure used to trap grease generated from food production establishments. It captures the grease and oils from the normal wastewater flow. The grease interceptor is generally located outside beneath the surface in a parking lot or sidewalk area located between the restaurant and the sanitary sewer line. Grease interceptors receive liquid waste from mop sinks, floor drains, and 3-compartment sinks. The city of Olathe requires that those operations containing grills and fryers and/or containing a 3-compartment sink are required to have a grease interceptor with a minimum capacity of 1000-gallons.

How does a grease interceptor work?
The purpose of the interceptor is to help separate the hot greasy water from other water generated at the restaurant. The interceptor slows the flow of the hot greasy water. As this water cools, the grease and oils separate and float to the top of this trap. This allows all other water underneath this greasy layer to flow down the pipe to the sewer. Larger-capacity grease traps are needed to provide adequate retention time for efficient grease recovery.

Why do we need grease interceptors?
Grease blockages not only cause many problems for restaurants, but for sewage collection systems and the wastewater treatment plants as well. The interceptor was designed to trap as much of the grease as possible before it is directly discharged into a sanitary sewer line. If there is no interceptor or if it is not regularly maintained, there can be a major backup in the sewer system. The opening of sewer lines that have become clogged is very costly and the clean up of restaurant kitchens that have experienced backups is very time consuming. If a restaurant is found liable for a sewer backup, they will often pay for it with increased insurance premiums.

How often does a grease interceptor need to be pumped?
The City of Olathe lists any discharge exceeding 100 mg/L of grease and oil as unlawful. Compliance with this regulation may be attained by frequently pumping the grease interceptor. The frequency of pumping will differ with each restaurant, depending on the capacity of the grease interceptor, the amount of grease in the wastewater, and the degree to which the facility has contributed to blockages in the past. Routine monitoring is the only way to determine the correct pumping frequency. All grease interceptors should be cleaned at least twice each year depending on the establishment. Some will find it necessary to clean them as much as twice a month, and if you must clean it more often, you may want to consider installing a larger interceptor.

Avoid back-ups with proper maintenance:
Poorly maintained grease interceptors in restaurants lead to sewer overflows and backups that can cause health hazards, damage property, and threaten the environment. In many cases, restaurants will be required to close or interrupt service due to problems associated with sewer backups.

Tips on grease:
Aside from installing and maintaining interceptors, there are a few simple things you can do to help control grease…

  • Install "no grease" signs near sinks to remind staff to avoid dumping fry grease, hood-vent grease or any other fats down the drain.
  • Contract with a grease recycling service to provide a waste container or bin.
  • Food wastes from plates should go in the trash not down the drain.
  • Pre-wash plates by spraying them off with cold water over a small mesh basket positioned over the drain. (This basket should be emptied into a garbage can).