Kansas Administrative Regulations
Agency 5 - DEPARTMENT OF AGRICULTURE-DIVISION OF WATER RESOURCES
Article 40 - DESIGN OF EARTH DAMS
Section 5-40-56 - Maximum design velocity for an auxiliary spillway

(a) The maximum velocity in feet per second during the design storm for water flowing in a vegetated earthen auxiliary spillway shall be determined from the following table:

Slope of the exit channel

Vegetation Erosion-resistant soils Easily erodible soils

0% to 5% 5% to 10% 0% to 5% 5% to 10%

Bermuda grass

and Bahia grass 8 7 6 5

buffalo grass,

Kentucky blue

grass, smooth

brome grass, tall

fescue, and reed

canary grass 7 6 5 4

sod-forming

grass-legume

mixtures 5 4 4 3

weeping love

grass, yellow

bluestem, and

native grass

mixtures 3.5 3.5 2.5 2.5

(b) The maximum design velocities specified in subsection (a) may be increased by not more than 10 percent if the design frequency of use of the auxiliary spillway is not more than two percent. The maximum design velocities may be increased by not more than 25 percent if the design frequency of use of the auxiliary spillway is not more than one percent.

(c) For exit channel slopes greater than 10 percent, the applicant shall provide analyses showing both of the following:

(d) The provisions of paragraphs (c)(1) and (2) may be used for slopes of 10 percent or less in lieu of the maximum values specified in the table in subsection (a).

(e) The maximum allowable design velocity for water flowing over the following types of materials shall be determined from the following table:

Material Maximum velocity allowed in feet per second

stratified rock 8.0

sound rock 13.0

(f) Channel lining materials not reliant on vegetation, including concrete, riprap, and grouted riprap, may be used if the applicant demonstrates that the lining will not fail during the spillway stability design event specified in paragraph (c)(2).