To the extent feasible, existing installations shall be maintained in accordance with, and if altered, repaired, renovated or converted, shall conform with, the I.I.A. Incinerator Standards Specifications adopted as part of this chapter. Prior to altering, renovating, or converting any existing incinerator, the owner or person in charge thereof shall apply for an alteration permit therefor from the Director, specifying the type and nature of any such change in the installation. The Director may condition the said permit on compliance with the aforesaid standards to the extent compliance is feasible. Upon request of the owner, the Director shall hold a hearing upon written notice and within 15 days of the aforesaid request on any proposed condition or order of the Director requiring compliance with the said standards, at which time the applicant may present such proofs, information, or data as may relate to the issuance of the alteration permit, the conditions attached thereto, and the applicability and feasibility of the aforesaid standards. In determining feasibility as applied to proposed changes in existing incinerators, the Director shall weigh the physical and financial difficulties of making such change as against the effect of such change in eliminating or curtailing the likelihood of air pollution. The Director shall make a determination of the said application or order within 10 days after the hearing. This section shall not be deemed to supersede the applicant's obligation to obtain necessary permits from other governmental agencies.