Is there a time period that constitutes "present at the facility?"

A facility owner/operator makes a specialty chemical by first producing one chemical- the reaction intermediate and then injecting chlorine into the reaction vessel to start the final reaction for the final product.  The facility runs these batches 3-4 times a year.  The reaction intermediate is present over 10,000 pounds on those days that the batches are run for about a half a day.  The facility is required to have a Material Safety Data Sheet (MSDS) for the intermediate.  Since the substance is not on site for 24 hours, must it be reported on Tier II?

Since the facility owner/operator is required to prepare and have available a MSDS for the reaction intermediate, the substance is subject to Section 312.  For the substance to be reportable, it must be present at the facility above the threshold planning quantity - 10,000 lbs.  Since no time period is specified for "present at the facility," it is implied that if the substance is present at any one time during the year above the threshold it is reportable.  Therefore, since the reaction intermediate is present at the facility over 10,000 lbs at one time, the substance is reportable under Section 312 and must be included on Tier II.  Also, the facility owner/operator may want to indicate in some way what three days the intermediate will be present in order to simplify planning for the facility.