§ 7-99. Preliminary drainage plan.

A. 

Submittal and approval. A preliminary drainage plan shall be required and submitted to the City engineer in conjunction with all preliminary plats and shall be mandatory for all changes in land use from that existing as of the date of this Part 7, which is November 4, 1982. This drainage plan shall be reviewed and approved by the City engineer before a final drainage plan and final plat will be accepted by the City for consideration. The City shall approve conditionally or disapprove the drainage plan in writing within thirty calendar days of the submittal. If the preliminary drainage plan is disapproved, resubmittal of the entire drainage plan will be required before reconsideration of the plan will be undertaken by the City engineer.

A drainage plan shall not be required for single-family or duplex unit building permits, but shall be required for all other building permits (multi-family [more than two], commercial, industrial, public facilities, etc.), and for all land development or subdivision of lands. In addition, these special building permit drainage plans will conform with section 7-100B, items (3), (4) and (5).

B. 

Contents. The preliminary drainage plan shall contain design calculations and other supporting data showing how the development proposes to meet the general storm water drainage standards stated in this Part 7. This preliminary drainage plan and calculations must be prepared and signed by a professional engineer registered in the state. It shall, in general, also contain the following:

(1) 

A preliminary engineering plan which shall identify how the runoff from major rain storms will be conveyed by the site's swales, storm sewers, natural drainage ways, and streets during and after construction.

(2) 

A preliminary drawing that shows the development's position in the drainage basin and how it would be developed so as not to adversely affect upstream and downstream storm water flows.

(3) 

Preliminary hydrologic and hydraulic calculations and a general layout drawing showing the proposed location and approximate sizes and grades of storm sewer lines, catch basins, pumps, detention basins, and other storm water drainage structures.

(4) 

Where storm drainage facilities are to be discharged into a canal or ditch, the following two items shall be submitted, along with the preliminary drainage plan.

(a) 

A copy of a letter of approval or other written permission from the drainage district, irrigation district, canal company, or whatever agency holds legal responsibility for the canal or ditch. This letter shall also contain documentation of peak canal or ditch capacity and freeboard requirements, as well as the present and future required irrigation district or canal company required capacity.

(b) 

A layout showing the proposed location and approximate sizes and grades of any detention or treatment facilities required by the said agency responsible for the canal or ditch.

(c) 

Access easement and method for cleaning canal or ditch.

(5) 

Where lands to be developed lie within the one-hundred-year floodplain, the one-hundred-year floodplain elevations and the proposed finish floor elevations of each building shall also be submitted.