Every person maintaining an office and ambulance facility and operating an ambulance business within the city for a period of six months or more prior to the effective date of the ordinance codified in this chapter shall be presumed, in the absence of any contrary evidence and finding of the city manager, to have provided prima facie evidence of public convenience and necessity, and the city manager, upon application received not later than fifteen days after the effective date of the ordinance codified in this chapter, shall grant a certificate of public convenience and necessity. (Ord. 473 §1, 2002).