Frequently Asked Questions on Fats, Oil and Grease

1. Why is my oil and grease discharge high?

There are generally three reasons for high oil and grease levels discharged from food preparation facilities. First, kitchen personnel may be disposing of used oil down the drain. This is rarely the case, however. Second, some older buildings do not have grease interceptors, or outside grease traps, to capture grease normally generated from kitchen activities. Third, poor maintenance, or no maintenance at all, of grease retention devices is the major contributor to oil and grease problems


2. What can I do to lower the levels of oil and grease being discharged to the public sanitary sewer?

Oil and grease levels can be lowered in several ways. First, your employees should be carefully instructed in the procedures to properly dispose of oil and grease. As an example, oil from deep fryers should be put in a rendering barrel. Second, you should consider the installation of an outside grease trap of adequate size and proper design to capture the oil and grease from your wash water. Inside grease interceptors are generally not as effective as an outside grease trap because they do not provide sufficient detention time for the water to cool and release the grease. This is particularly true where automatic dishwashers are used.Third, and probably most important, proper maintenance of inside grease interceptors and outside grease traps can lower the oil and grease levels discharged to the public sanitary sewer. Grease interceptors should be cleaned out in accordance with the manufacturer’s recommendations, generally once a week, depending on the size of the interceptor and the volume of water discharged through it. Outside grease traps should be cleaned out about once every month or two. Greater the grease accumulation, in either device, greater is the frequency of maintenance. Grease traps and interceptors sometimes, unfortunately, are not maintained for years, or until they begin to back up into buildings.


3. What else can be done to lower oil and grease?

A. There are several “biological” and chemical products on the market that may lower oil and grease levels, when used in combination with grease retention devices. Bacteria, either freeze dried or liquid, and other micro organisms can be introduced into the kitchen drainage system late at night. The organisms multiply in the grease traps and pipes and attack grease. This method does require a period of no flushing to be effective. There are chemical products on the market that also act upon grease, however, caution should be exercised. Use of chemicals may alter the pH of your discharge. The pH range for Henrico County is 5.0 -11.0, and is enforced.B. Grease will build up in the pipe between the source of grease and the grease trap, or public sewer. As hot water passes through the pipe and over the grease, some grease will be picked up and carried to the public sewer where it cools down and solidifies on the walls of the pipe. Jet cleaning, or steam cleaning your connection from the public sewer to the source of grease will remove the grease in your line and lower the grease levels discharged to the public sewer.C. Before making any major alterations to your system, discuss the problem with a knowledgeable plumber.D. Should the problem being experienced require you to install a “pollution abatement device,” that device may be exempt from the State Sales and Use Tax. If you wish to know more about the procedures to qualify for this exemption, contact the Monitoring and Compliance Section Manager..


Should you have further questions pertaining to oil and grease problems, contact the Monitoring and Compliance Section Manager at telephone number (804) 501-7609.

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