(A)

This Subsection is intended to ensure that planning and design of drainage systems shall not be such as to transfer the problem from one property to another or to create a more hazardous or damaging condition downstream.

(B)

Drainage shall be shown on the site development plan, and shall be prepared by a licensed, professional engineer for proposed development sites above one acre in area, or when natural or existing drainage patterns are significantly altered, or when concentration of flow off-site is proposed, or when large impervious surfaces such as parking lots are proposed.

(C)

Design of all improvements shall conform to City standards for storm drainage systems, including, but not limited to, Section 11-5-13 of this Title and Colorado Department of Public Health and Environment Municipal Separate Storm Sewer System (MS4) permit requirements. Whenever possible, the flow shall be routed to a natural drainage or City storm drainage facility. All drainage systems designed to drain water from private property to City rights-of-way shall be approved by the City.

(D)

Design of drainage systems shall be based on the level of protection required for various land uses; major drainage systems shall be based on the runoff expected from the 100-year storm, unless otherwise determined by the City. Drainage from a development shall not increase erosion or increase flooding problems in the receiving drainage. Drainage shall not degrade the quality of surface and groundwater by increasing sedimentation or by introducing other detrimental constituents.

(E)

When a proposal would result in the alteration of natural or existing drainage patterns or the concentration of flow, an analysis prepared by a professional engineer must be, provided that demonstrates receiving drainage ways (either natural or manmade) have sufficient capacity to convey the altered flows without causing increased damage, hazard, or liability. The analysis shall address cumulative drainage effects, not only from the development but also from other development within the same drainage basin. The concentration of flow or alteration of drainage patterns must not result in increased erosion to downstream properties.

(F)

Acquisition of all permits required by state and federal authorities for work to be done within or adjacent to an established waterway, irrigation canal, drainage system, or designated floodplain or floodway is the sole responsibility of the applicant. A copy of these permits shall be attached to the application.

(Ord. No. 2677, § 1(exh. A), 12-17-2024)