Also note if the flow enters the trap evenly. You may use food coloring or dye tablets to check which if any appliance are connected to the unit. If the trap does not have sufficient capacity to allow for cooling grease will again be discharged into the sewer. Many treatment facilities requiring cooling jets that are activated to cool the water as it enters the interceptor. Even if the grease amount isn't a lot as it cools it accumulates on the interceptor pipe walls and causes a plug.
Hot grease cools quickly in a sanitary sewer.
Improper or Frequency of Maintenance Interior grease traps should be evaluated for cleaning needs on a weekly basis. Depending on the size and volume it may need to be cleaned more or less. If heavy grease is accumulating in the outlet baffle of the trap it needs to be cleaned more often. Proper and frequency of maintenance is the only sure way to know if your trap is operating properly. Dip accumulated grease out from the top and place it in a watertight container such as a plastic bag.