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Oil, grease and solid wastes discharged into the sanitary sewer by commercial or industrial users can cause a number of problems in the sewer system. Grease & oil have poor solubility and tend to separate from the aqueous phase. Although this characteristic is advantageous in facilitating the separation of oil & grease in pretreatment devices such as grease traps and interceptors, it complicates the transportation of wastes in the sewer and can complicate treatment and disposal at the wastewater treatment plant.

Oil and grease in wastewater from food service facilities can result in decreased carrying capacity of sewers due to congealed, cooled grease which coats the inside of the pipes. Once a pipe becomes constricted, the potential for a stoppage increases. Stoppages can and will eventually cause sanitary sewer overflows. In order to ensure efficient sewage treatment, protect the sewer system and protect public health, the City of Santa Cruz has established the following requirements for businesses.

General Requirements

  • Any type of business where oil and grease may be discharged into a public sewer shall have an interceptor/trap. The interceptor or trap shall be of a type and capacity approved by the Director.
  • Each interceptor or trap shall be installed and connected so that, at all times, it is easily accessible for inspection, cleaning and removal of grease and other material. Interceptors or traps installed outside of the building shall be constructed in such a manner so as to exclude the entrance of surface water and storm water.
  • The interceptor or trap shall be situated on the User's premises.
  • Buildings remodeled for use requiring interceptors/traps shall be subject to these regulations.
    Waste discharges from fixtures, including but not limited to, scullery sinks, pot and pan sinks, mop sinks, soup kettles and floor drains, shall be drained into the sanitary sewer through an interceptor/trap. Toilets, urinals and other similar fixtures shall not drain through the interceptor/trap.
  • Interceptors and traps shall be maintained in efficient operating condition. At minimum, grease traps must be cleaned monthly or as deemed necessary by the Industrial Waste Inspector. The use of chemicals, bacteria or other agents to dissolve grease or otherwise clean grease interceptors/traps is specifically prohibited. No such grease shall be introduced into any drainage piping or public or private sewer.
  • Large capacity concrete type interceptors shall have a suitable sample box to provide access for collection of wastewater samples. Large interceptors must be serviced every three-months or as deemed necessary by the industrial waste inspector.
  • Each appliance connected to a pre-cast under sink type grease trap shall have a flow device installed. No dishwasher may be connected to these types of grease traps.
  • A record of grease trap cleaning or copies of grease interceptor servicing must be maintained for a twelve-month period and made available for inspection by the city's representative.

Additional Information
There are two basic types of grease interceptors…

    These are commonly referred to as traps and typically are located under sink units. These traps should only be used where oil and grease waste are minimal. These units are rated in pounds of grease capacity. (e.g. 100 pound unit).
    • Dishwasher Connection Prohibited: Automatic dishwashers may not be connected to grease traps or interceptors less than 750 gallon capacity.
    • Installation: Each trap shall be installed and connected so that it is, at all times, easily accessible for inspection, cleaning and removal of intercepted grease and other material.
    • Maintenance: The trap shall be maintained by the owner, at his/her expense, in an efficient operating condition at all times, with a minimum monthly removal of the accumulated grease and other material. A log of grease trap cleaning must be maintained and made available for inspection. If a trap cleaning service is used, dated receipts must be available for inspection.
    These types of tanks are commonly referred to as interceptors and are usually installed below ground. Capacity of an interceptor is rated in gallons of liquid (i.e. 1,500 gallons).
    • Dishwasher connection required: Dishwashers must be connected through interceptors with capacities of 750 gallons capacity or more.
    • Installation: Each interceptor shall be installed and connected so that it is easily accessible for inspection, cleaning and removal of intercepted grease and other material. Installations of large tanks require experienced licensed contractors to perform excavation work and placement of the tank.
    • Maintenance: These types of interceptors require maintenance that can only be provided by an interceptor tank pumping service. When emptied, the units should be thoroughly washed and all interior plumbing connections inspected for completeness and integrity. Dated receipts of interceptor pumping must be maintained for a twelve-month period and be available for inspection.

Sizing Criteria
The following criteria are used to determine the size of a trap/interceptor:

    1. Uniform Plumbing Code
    2. Number of meals being served
    3. Seating Capacity
    4. Volume of wastewater being discharged
    5. Retention time and storage factor ratings
    6. Type of foods being prepared (cooked versus uncooked)
    7. Disposable or washable dishware
    8. Type of food service facility (fast food, sit down restaurant, cafeteria)
    9. Frequency of maintenance or lack thereof
    10. Accessibility of installation

For more information please contact:
Akin Babatola
Laboratory/Environmental Compliance Manager
110 California Street
Santa Cruz, California 95060
(831) 420-6045
Fax: (831) 420-6489

Last updated: 11/2/2009 10:41:45 AM