As soon as practicable after the enactment of this chapter, a comprehensive emergency management and disaster control plan shall be adopted by resolution of the Commission upon the recommendations of the City Manager. In the preparation of this plan as it pertains to city organization, it is the intent that the services, equipment, facilities and personnel of all existing departments and agencies shall be utilized to the fullest extent possible. When approved it shall be the duty of all municipal departments and agencies to perform the functions and duties assigned by the plan and to maintain their portion of the plan in a current state of readiness at all times.