The Director shall review the petition and may request additional information and technical studies necessary to comply with the California Environmental Quality Act (CEQA). All efforts shall be made to utilize existing information contained in the City's General Plan Environmental Impact Report (EIR). If an Environmental Impact Report (EIR) is required, upon certification of the EIR, no further EIR or Negative Declaration (pursuant to the California Public Resources Code Sections 21000 et seq.) need be filed for any project which is undertaken pursuant to and in conformity with, the adopted Specific Plan for which the EIR has been certified. An amendment to the Specific Plan, proposed uses or environmental impacts not adequately addressed by the certified EIR or other CEQA compliance document, will require an environmental assessment which may necessitate a Supplemental EIR or other appropriate documentation. Such Supplemental EIR or other appropriate CEQA document shall be processed along with the amended Specific Plan as provided in this section.