Wastewater contribution permits shall be issued for a period not to exceed two years. SIUs shall apply for permit reissuance a minimum of ninety days prior to the expiration of an existing permit. The terms and conditions of the permit may be subject to modification by the City during the term of the permit as limitations or requirements included in this chapter are modified or other just cause exists. The SIU shall be informed of any proposed changes in his permit at least sixty days prior to the effective date of the change. Any changes or new conditions in the permit shall include a reasonable time schedule for compliance.