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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Except as ...-.lifiP<l herein, tre criteria set forth in tre USIDl will be used in analyzing
and approving tre adequocy of streets as a functim of tre drainage system. Both the initial
storm rumff am IIEljcc storm runoff DJJSt be cmsi.dered and ....l...,lAHrns Sndng su:h rmoff at
critical sectia1s man be suIJIrl.tted. The following criteria shall apply in tre determinatim
of allowable street flow capacities:

a. Street, curb/gutter CI06S!B'l8, am curb cuts shall conform to Town of Ordway Standard
Specifi.catioos far tre Design am Coost:roction of Streets, QJrb am Gutter, am
Sidewalks, latest revisial thereof (see Part II of this nrnmal).

b. Street Capd,ty for Initial St:0rn5. PaveIent encroacl1Ient far tre initial design stann
shall IlCM exceed tre limitatioos set forth in the Table 1. 9.

c. Street ~ty for l-bjor Stann. The all~ depth of flow am immdated area far
tre DBjar design storm shall not exceed tre limitations set forth in tre Table 1.10.

d. Cross Street Flow. Cross street flow can occur by tI<<l sepnate 1IE!81lS. ere is ruooff
which has been flowing in a gutter am then fl!Ml across tre street to the opposite
gutter ar inlet. The second case is flow from sooe external !D\II"CE!, su:h as a
dra:inageley ar coodui.t, which will flow across tre crown of tre street ..ren tre coodui.t
capacity is exceeded. The rrexinnJn allowable cros&-seCti.aI flow depth, lased Q1 tre
1oUI'St camtim, shall not exceed tre limitati.oos stijW.ated in Table 1.11.

e. Capacity o.l,-,.l".-;oos. All thooretical flow capeciti.es shall be reduced by the
appropriate redu:tion factors to obtain al1owah1.e flow capacities.

3.12 ~....H.... Storage

futentioo facilities shall be provided to cootro1 the peak storm 1ol8ter runoff rates to
historic (llI1leveloJBi) peak ruooff flow rates far all new land develoIJlBlts and any land
redevelOIJl5lts. The detention facility sIn11d be constnxted outside the DBjor drainageway. If
tre detention facility is located on a DB jor drainageway, the required volun:e and release rates
shall be lased upon the entire lBsin tributary to tre drainageway. In additim, the off-si.te
runoff swuld be routed around the detention p<nI, ot:hen.oise the required volun:e and release
rate sha11 also be lased UjXIl tre entire tributary area. Iimgn criteria for storage volun:e
requirE!lEnts, release rate and type of facility are presented in the lEJX}I "Storage".

3.13 Hydraulic Stnrtures

Hydraulic stroctures are used in storm drainage wrk to cootrol tre flow of tre runoff.
The energy assnriated vith flowing water has the potential to create damge to the drainage
wcrks, especially in tre fann of erosion. Hydraulic stroctures, which include riprap, energy
dissijBtors, check stroctures, bridges, and irrigation ditch croosi.ngs, all cootro1 tre energy
and minimize tre damge potential of stonn runoff.

The criteria to be used in tre design of hydraulic stroctures shall be in accordance vith
the \EIXM ''Majar Drainage" am "Structures." The specific criteria to be used with the
ODdificatioos for the Ordway area are presented herein.

3.13.1 Ripzap

The design of riprap protection for culverts, channel protectioo, check drops, bridges,
gabioos ar other areas subject to erosion shall be in accordance with \EIXM ''Majar Drainage,
Sa:tion 5 Riprap."

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