Prior to issuance of a conditional zoning certificate to erect a new tower structure, every applicant shall deposit with the city a performance guarantee which shall be conditioned upon compliance with this subchapter. The amount of the guarantee, not less than $5,000 nor more than 10% of construction costs, shall be set by the Planning Commission. Such guarantee shall be conditioned upon compliance with all aspects of this subchapter and must be applicable to any assignee and owner of any permit granted hereunder, or any employee, contractor, subcontractor or other party performing services in connection with any conditional zoning certificate issued under this chapter. The performance guarantee shall be released only upon demolition of the tower and restoration of the site to the pre-development conditions. The format of the guarantee shall be approved by the Director of Law.