Grease traps must be provided at installations
such as restaurants, nursing homes, schools, hospitals or other installations
from which large quantities of grease can be expected to discharge.
Grease traps shall be installed in a separate
building sewer serving that part of the plumbing system into which
the grease will be discharged. The discharge from the grease trap
must flow to a properly designed septic tank or building sewer prior
to the septic tank.
Grease traps shall have a minimum depth of four feet and a minimum capacity of 1,000 gallons and shall have sufficient capacity to provide at least a twenty-four-hour detention period for the kitchen flow. Kitchen flow shall be calculated in accordance with § 223-16.
Grease traps shall be watertight and constructed
of sound and durable materials not subject to excessive corrosion,
decay or frost damage or to cracking or buckling due to settlement
or backfilling Tanks and covers shall be designed and constructed
so as to withstand normal structural loadings. A tank installed in
groundwater shall be weighted to prevent the tank from floating when
it is emptied.
The inlet tee shall extend to the mid depth
of the tank. The outlet tee shall extend to within 12 inches of the
bottom of the tank. Tees shall be cast iron or Schedule 40 PVC and
properly supported by a hanger, strap or other device.
Baffles may be provided as necessary to maximize
the separation of grease from the sewage. Baffles may not be considered
as a substitute for inlet and outlet tees.
Grease traps shall be installed on a level,
stable base that will not settle.
Grease traps may be constructed of poured reinforced
concrete or prefabricated material acceptable to the approving authority.
Grease traps shall be provided with a minimum
twenty-four-inch diameter manhole frame and cover to grade over the
inlet and outlet.
Grease traps shall be located on the lot so
as to be accessible for servicing and cleaning.
The invert elevation of the inlet of a grease
trap shall be at least two inches above the invert elevation of the
outlet. Inlet and outlet shall be located at the center line of the
tank and at least 12 inches above the maximum groundwater elevation.
Backfill around the grease trap shall be placed
in such a manner as to prevent damage to the tank.
Grease traps shall be inspected monthly and
shall be cleaned when the level of grease is 25% of the effective
depth of the trap, at least every three months.
