FLOOD09884

• County: Crowley
• Community: Ordway
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: Drainage and Street Design Manual for the Town of Ordway
• Date: 1/1/1987
• Prepared For: Ordway
• Prepared By: Simons Li & Associates Inc.
• Floodplain - Doc Type: Project

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'DE fol1o<<ing design criteria shall be fin H...n far all culvert design:

a. 'DE culvert :IJ1cl.uI1ng inlet am outlet slJ:'octures shall properly
take care of water, bedlred am debris at all stages of flow.

b. Inlets. Culvert inlets shall be designed to minimI.ze ..d..",...e and fr:I.ctia11osses.
Inlets shall be provided with ei.tIe' f1ared-end sections ar l-n....ll.. with wing walls.
Far large stIu::tures, provisions shall be 0Bde to resist possible slJ:'octural failure
due to hydrostatic uplift forces.

c. <A1t1ets. Culvert ootlets shall be designed to avoid -ti-ttatim, 1Diermlni.ng of the
culvert, ar erosi.m of the dcNnst:rean channel. <btlets shall be provided with ei.tIe'
f1ared-e1d !ECtims ar beadwalls with wing walls. Additimal ootlet cmtrol in the
farm of riprap, channel shaping, etc., my be required lotJere e'XC-vely high dis:harge
velocities =.

d. Slopes. Culvert slopes shoold be su:.h that nei.tIe' silting oor "",..",,,rlve velocities
and s::our =. Generally, the mininun slope of culverts shall be limited to O.~
percent.

e. Haadwater. Generally, the readwater to d:i.anEter (IM/D) ratios
Sloold mw exceed three recaJIIEOOed in Table 1.8.

f. Tailwater. 'DE height of tailwater at the oot1et shall be subject
to the criteria set forth in Subsection (e) above.

g. Hydrnulic Ja>ign. Culverts shall be analyzed to deternrl.ne ..rether
discharge is controlled by inlet or outlet COIXii.ti.ms for both the initial storm
discharge and the IIBjor storm discharge. 'DE value of the roughness coefficient (0)
used shall not be less than three speciiied in Table 1.3. Canputations for selected
allvert sizes shall be subDitted for approval on farms <<inril.... to those inclllled in
these speciiications.

h. Min:iJJm Allco.ab1e Size. 'DE required size of the all vert shall be !Bsed upm adequate
hydraulic design analysis. In no case, m.ever, will approval be Dade for round
all verts with less than 24 inches inside d:i.anEter, or for culverts of any other shape
which have a cross-sectiroal area less than 3.14 square feet.
1. l-bJltiple Culvert Installatims. 'DE slJ:'octural design of culverts shall cooform to
three netOOds am criteria recaJIIEOOed by the lIBIIUfocturer of a speciii.c type of
allvert for the speciiied l'!ll!lanknent cooditims.

3.11 lk'ban Street Evsol.,.,H....

'DE following sections present the speciii.c design requiraIents for storm drainage of urban
street. With regard to drainage, the urOOn street evaluation c:msists l!Binly of determining the
allowable gutter flow caprity. IIhen the allowable cajEcity is equaled ac exceeded, a storm
sewer systan is required to reduce the storm runoff in the streets to acceptable values. 'DE
allowable cajEcity is a fuoction of the street rl"..<rlficatim, am physical properties su:h as
loogitu:linal and cross slope, width, and gutter configuraticn. Also considered in the allohable
cajEcity is the safety and DBintemnc.e aspects of storm runoff within the street.

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