Any application for zoning approval within the boundaries of the Downtown Design Overlay District shall be transmitted to the Plan Commission (with advice from the Downtown Design Advisory Committee) for review and approval. In addition to the information required for a zoning permit, a detailed description of the construction, alteration, demolition, or use proposed, together with any architect drawings or sketches if those services have been utilized by the applicant, and, if not, a sufficient description of the construction, alteration, demolition, and use to enable a determination of what the final appearance will be, shall be required. On large-scale projects, it is suggested that conceptual plans be submitted for preliminary review prior to submitting detailed plans. Upon receiving an application for a zoning permit requiring approval by the Plan Commission, the Building Inspector shall contact the Commission Chairperson and schedule a meeting within 15 days. Publication of a public hearing notice shall not be required. The Plan Commission (with advice from the Downtown Design Advisory Committee) shall conduct the hearing and act on the application within 15 days following the hearing.