A developer who wishes to extend sewer facilities shall employ a civil engineer registered in Arizona to perform the field engineering and prepare detailed plans and specifications for the main sewer extension. The final detailed plans and specifications for the main sewer extension shall be approved by the city before construction begins. The design and engineering shall be in accordance with the specifications of the city prior to construction. The construction shall meet city specifications, requirements and approval, and shall be subject to inspection by the city during construction. Subject to the provisions of this chapter, the city agrees to permit the developer to connect into the existing trunk sewer lines of the city and the main sewer line to be constructed by the developer as herein provided. (1976 Code § 11-4-2)