(a) Drawings showing cross sections, profiles, elevations, construction details, grading plans, specifications and cost estimates, and all calculations and computations for all required improvements shall be prepared by a professional engineer. The improvement plans shall be prepared as directed by the City Engineer and subject to his approval.
(b) If it becomes necessary to modify the improvements as approved, due to unforseen circumstances, the subdivider shall inform the City Engineer in writing of the conditions requiring the modifications. Written authorization from the City Engineer to make the required modification must be received before proceeding with the construction of the improvement.
(c) At the completion of the construction, and before acceptance, the subdivider shall furnish the City Engineer a set of linen or mylar tracings for permanent record, showing the locations, sizes and elevations of all improvements as constructed.