Best Management Practices

City of Shepherdsville Wastewater Treatment Plant best management practices for fats, oil and grease for food service facilities

Fats, oil and grease (FOG) can have negative impacts on wastewater collection and treatment systems. Most wastewater collection system blockages can be traced to (FOG). Blockages in the wastewater collection system are serious, causing sewage spills, manhole overflows, or sewage backups in homes and businesses. This manual is written to provide restaurant and fast food business managers and owners with information about FOG pollution prevention techniques focused on their businesses, effective in both reducing maintenance cost for business owners, and preventing oil and grease discharges to the sewer system. The discharge of FOG to the sewer system is illegal. Ensuring that grease trap and grease interceptors are properly installed and most importantly, properly maintained, is the key to avoiding enforcement action against your business. This manual focuses on proper maintenance of grease traps and interceptors, and includes inspection checklist for the business owner/manager as a guide to how and what Sewer pretreatment inspectors will be checking during an onsite inspection.

Manual contents includes

  • Frequently Asked Questions (FAQs)
  • Best Management Practices
  • Prohibitions
  • How It Works
  • Maintenance
  • Compliance Inspection an Installation Checklist

Knowledgeable business managers can effectively prevent oil and grease buildup and associated problems for both the sewerage agency and the restaurant owner.

Frequently Asked Questions About FOG

Large amount of oil and grease in the wastewater cause trouble in the collection system pipes. It decreases pipe capacity and, therefore, requires that piping systems be cleaned more often raising cost for all taxpayers. Oil and grease also hamper effective treatment at the wastewater treatment plant. Grease may not appear harmful but it congeals and causes nauseous mats on the surface of settling tanks, digesters, and the interior of pipes and other surfaces which may cause shutdown of wastewater treatment units. Problems caused by waste from restaurants and other grease-producing establishments are the reason the Shepherdsville Sewer Department requires the installation of pretreatment equipment, commonly known as grease traps or interceptors.

Any establishment that introduces wastewater containing grease or oil into the sewage system is required to install an interceptor or in limited cases, and interior grease trap (point source). Interceptors are usually required for high volume fast food or full menu establishments such as hotels, hospitals, factories, or school kitchens. In some instances, interior grease traps may be allowed for small volume fast food or take-out restaurants with limited menus, paper plate service, minimum dishwashing, and/or minimal seating capacity. Electro-mechanical, self cleaning type grease traps are the accepted standard. These are generally referred to as Automatic Grease Interceptors (AGI). All specified devices must meet local plumbing code regulations.

When waste pretreatment is required by the sewer department an approved grease trap or interceptor shall be installed according to the Uniform Plumbing Code. The Sewer Department Pretreatment staff will assist the establishment in determining if a grease trap or interceptor is required and the appropriate sizing. The Shepherdsville Sewer Department Pretreatment Inspector make routine periodic inspections to verify that mandatory maintenance BMP’s are being implemented. These BMP’s are fully enforceable under the Sewer Department regulations.

If you are uncertain whether you establishment has a grease interceptor, or trap, you should contact the Shepherdsville Wastewater Pretreatment Inspector for assistance. You may request a “voluntary compliance” visit by the Shepherdsville Pretreatment Inspector without the risk of an enforcement action. You will be required to comply with any request for cleaning or other maintenance.

A grease trap is typically located under the sink or other kitchen fixture to which it is connected. Baffles in the trap interior slow the wastewater down long enough for the grease to separate and rise to the surface. The grease can then be removed and disposed properly. Passive traps must be cleaned manually, a dirty and smelly job! Electro-mechanical devices require less manual maintenance and are more efficient because accumulated FOG is automatically removed daily.

An interceptor is a buried vault with a minimum capacity of between 1000 and 1500 gallons located on the exterior of the building. The vault includes a minimum of two compartments, and flow between each compartment is through a configuration of pipe fittings designed to allow for solids settling and grease retention. The capacity of the interceptor provides adequate detention time so that the wastewater has time to cool, allowing grease to separate and rise to the surface where it accumulates until the interceptor is cleaned. See How it Works section in this document for a description of how various components of a grease interceptor function.

Refer to Grease Trap and Interceptor Maintenance section in this document.

Based on historical inspection observations and established best management practices, most grease interceptors need to be cleaned every 60 to 90 days. Some establishments will find it necessary to clean their traps more often. In some instances, light menu, low volume facilities may be able to clean less frequently. Only rarely does a facility have to pump less frequently than every six months. Demonstrating thru accurate record keeping that a less frequent cleaning schedule is fully adequate is the responsibility of you the business owner/manager. It is not the Sewer Department responsibility. Securing a service contract with a qualified pumping contractor for routine inspection and cleaning as needed is the best way to avoid enforcement action by the Sewer Department and the City of Shepherdsville. Waiting until a Sewer Department inspector arrives on site and requires you to clean your interceptor is not an acceptable best management practice and will result in an enforcement action.

Failure to implement the required FOG BMP’s is a violation of the Sewer Department Regulations. Additionally, if the establishment fails to adequately maintain its trap or interceptor, it will eventually encounter a maintenance problem with a plugged building sewer line. The blockage can create a sewer backup situation and ultimately potential health problems in the establishment. If the problem is in the building sewer line, then the establishment has direct responsibility for paying for the maintenance. If the blockage or restrictions occurs in the Sewer Department sewer main then the establishment will have to pay for the Sewer Department’s line cleaning cost. The discharge of grease to a sanitary sewer line in amounts “which will or may cause obstructions” is a violation of the Sewer Department Regulations and will result in enforcement action including cost recovery, fines and/or penalties.

Criteria for Inspecting Grease Traps/Interceptors

All food service establishments are inspected for compliance with BMP’s. The following general criteria are used by Pretreatment inspectors during trap or interceptor evaluation and are offered here for information purposes only. The judgment of the onsite inspector is final.

Percent of hydraulic capacityConditionsInspector Action
25%GoodCheck records for the last date cleaned. Maintain normal schedule.
25 – 50%Fair to PoorCheck next schedule date for cleaning.
Advise facility to schedule soon.
Order revision of cleaning schedule as necessary.
>50%Non-ComplianceOrder Immediate cleaning.
Order prescribed cleaning schedule.
Facility to call for re-inspection.

If the trap is in FAIR to POOR condition, the facility should be advised to schedule a cleaning event in the near future. The cleaning frequency schedule may need to be increased.

If the trap is in Non-Compliance, the facility is issued a compliance order to have it cleaned immediately. The facility is required to call for re-inspection within 7 days to verify that the trap or grease interceptor has been properly cleaned. An enforcement action including fines and/or penalties will be taken against facilities found in Non-Compliance a second time.

Best Management Practices (BMP’s)

Required FOG BMP’s – Maintain Grease Traps and Interceptors

BMPReason ForBenefits to Food Service EstablishmentPretreatment Inspection Checks
Clean grease interceptors routinely. 60 to 90 cleaning schedules standard unless facility can demonstrate a less frequent schedule is adequate. Securing a service contract with a qualified pumping contractor for routine inspection and cleaning as needed is strongly advised.Grease interceptors must be cleaned routinely to ensure that grease accumulation does not limit retention time and separation efficiency resulting in pass through of grease to the sewer. Waiting until the Sewer Department Inspector arrives on site and requires you to clean your interceptor is not an acceptable BMP and may result in an enforcement action.The cleaning frequency is a function of the type of establishment, the size of the interceptors, and the volume of flow discharged by the establishment. Routine cleaning is a required BMP. Avoid Sewer Department enforcement action.50% of the interceptor capacity as a combination of grease (top) and sediment (bottom) requires immediate cleaning.
Clean undersink passive type grease traps weekly unless facility can demonstrate a less frequent schedule is adequate. Accurate cleaning records or logs are required to be kept on site.If passive grease traps are more than 50%full when cleaned weekly, the cleaning frequency needs to be increased.Weekly cleaning of undersink grease traps serves to limit risk of enforcement action by the Sewer Department. If the grease trap is not providing adequate protection, the Sewer Department will require installation of additional grease abatement equipment.Visually inspect the undersink grease trap for flow restrictor.
Inspect cleaning records.
Electro-mechanical automatic traps-empty oil buckets daily. Clean solids strainer daily. Never remove flow restrictor. Clean wiper blades weeklySolids take up capacity and causes odors.Adequate maintenance ensures maximum efficiency.Check that electro-mechanical trap is plugged in and timer is set. Visually inspect the device for flow restrictor. Check solids basket. Inspect cleaning and maintenance records.
Keep maintenance logThe maintenance log serves as a record of the frequency and volume of cleaning the interceptor. It is required by the pretreatment program to ensure that grease trap/interceptor maintenance is preformed on a regular basis.The maintenance log serves as a record of cleaning frequency and can help the establishment manager optimize cleaning frequency to reduce cost.Inspect maintenance log. Confirm the maintenance log with the grease hauler identified.

Recommended FOG BMPs for Kitchen Operations

BMPReason ForBenefits to Food Service EstablishmentPretreatment Inspection Checks
Witness all grease trap or interceptor cleaning and maintenance activities to ensure the device is properly operating.The facility manager inspects the cleaning operation and ensures it is consistent with the procedures.The establishment will ensure it is getting value for the cost of the cleaning the grease trap or interceptor. Otherwise the establishment may be paying for the cleaning more often than necessary.Check condition of grease interceptor. Check for submerged inlet and outlet. Check for evidence of grease in outlet pipe. Check for evidence of overflow blockage.
Train kitchen staff and other employees about how they can help ensure BMPs are implemented.People are more willing to support an effort if they understand the basis for it.All the subsequent benefits of BMPs will have a better chance of being implemented and you can avoid enforcement actions.Talk to the establishment manager about the training program that he/she has implemented.
Post “No Grease” signs above sinks and on the front of dishwashers.Signs serve as a constant reminder for staff working in kitchens.These reminders will help minimize grease discharge to the traps and interceptor and reduce the cost of cleaning and disposal.Check appropriate location of “No Grease” signs.
Use a low temp chemical sanitization type dishwasher. Follow the Health Department regulations for sanitizing.Temperatures can be set at 120° F or less depending on type of chemical sanitizer used. The Uniform Plumbing Code (UPC) prohibits discharging any type discharging any type dishwasher to grease traps.The food service establishment will reduce its cost for the energy-gas or electric- for heating the water.Check boiler or hot water heater discharge temperature. Measure the temperature of the hot water being discharged from the closest sink.
Use a three-sink dishwashing system, which includes sinks for washing, rinsing and chemical sanitizing. Follow Health Department rules for sanitizing.The food service establishment will reduce its cost for the energy-gas or electric-for heating the water for the mechanical dishwasher and for operating the dishwasher.Measure temperature of the hot water at the three sink system. Note: The Uniform Plumbing Code (UPC) prohibits the discharge of dishwasher water to grease traps.
Recycle waste cooking oil.This is a good recycling opportunity. There are several waste oil recyclers in the area.Liquid wastes cannot go into dumpsters. Low cost for proper handling of the waste material.Obtain name of recycler used. Review recycling records. Confirm records with recycler.