The plant will operate 24/7, but the receiving facility will be open 24 hours per day for six days. At 0600 Sunday morning, there will be enough feedstock accumulated in at — plant storage for the normal 2.5-day buffer (60 h). Hauling operations begin again at 0600 Monday morning. At-plant storage is decreased to a 1.5-day buffer (36 h) to supply the material for weekend operation.

To discuss the 24-h-hauling concept, it is convenient to consider two SSL operations, a “day-haul” operation and a “night-haul” operation. For the day-haul operation, the racks are hauled as they are loaded.

For the night-haul operation, the required number of empty racks, enough for one day’s operation, are pre-positioned at the SSL. (Cost of pre-positioning the racks is not considered in this example.) The SSL crew loads these racks during their 10-h workday, and they are hauled during the night. Each truck arriving during the night leaves a trailer with two empty racks and hauls a trailer with two full racks. The next morning the loading crew will go to work on the empty racks delivered during the night and fill them during their workday.