Each permit shall be granted on the condition that the permittee procure, obtain and file with the City Clerk and maintain in full force and effect liability insurance insuring said permittee, its officers, agents and employees, as well as its subcontractors, their agents and employees, its lessees and tenants in the sum of at least $100,000.00 per person and $300,000.00 per accident and $50,000.00 property damage, or in such additional sums as shall be deemed necessary by the City Planning Commission, from liability to anyone who might be injured by reason of negligence or nonfeasance of said permittee or its subcontractors, or its agents, officers or employees or its tenants or lessees in the operation of said heliport or helicopters to and therefrom.