§ 18.5-11. Street drainage criteria.

All streets, as well as other drainage conveyances such as pipes and channels, shall be designed using Manning's equation. Runoff should normally be calculated using the "rational method." All calculations shall be in accordance with the current edition of the city's "Design Guidelines for Site Development and Infrastructure Construction" which document has been adopted by the city and is on file in the office of the city clerk. Streets shall be designed according to the following criteria using storm durations intensities applicable to the runoff basin being drained:

(1)

The basis for the design of local streets shall be the flow from a ten-year storm, which must be contained between the street curbs. Local streets shall carry the fifty-year storm within the public right-of-way.

(2)

Other streets shall be designed to carry the following minimum flows:

a.

Major arterial and arterial streets shall carry flows as determined by the city's master stormwater management plan.

b.

Collector streets shall be designed to carry flows from ten-year storms between the curbs and flows from fifty-year storms within the public right-of-way.

c.

In cases where the peak flows from the design storm exceed the above capacities, underground pipes with suitable discharge points approved by the city engineer shall be designed and installed along with all appurtenances necessary.

d.

Concrete valley gutters (MAG Std. Det. 240, as may be amended hereafter) shall be constructed at all intersections where the drainage pattern requires them. Valley gutters are not allowed to cross major arterial or arterial streets. All valley gutters not located at intersections shall be a minimum of six (6) feet in width. Asphalt valley gutters are not allowed on any public street or alley.

e.

The design flows must consider all potential flows from all possible contributing areas even though these flows may originate from areas removed from the immediate site.

(Ord. No. 1701, § 1, 10-29-91)