For the purpose of this subpart:
(a) The ``average process water usage flow rate'' of a cleaning water process in liters per day is equal to the volume of process water (liters) used per year by a process divided by the number of days per year the process operates. The ``average process water usage flow rate'' for a plant with more than one plastics molding and forming process that uses cleaning water is the sum of the ``average process water usage flow rates'' for the cleaning processes.
(b) The ``volume of process water used per year'' is the volume of process water that flows through a cleaning process and comes in contact with the plastic product over a period of one year.