FLOOD06000

• County: Arapahoe
• County: Adams
• Community: Aurora, Arapahoe County
• Stream Name: First Creek
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 3/1/1977
• Prepared For: Arapahoe County
• Prepared By: Engineering Consultants
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

CHIII'TEI, I I

METHODOLOGY

General

During the Board meeting of December :~.1, 1.974, to-he Fj rst Creek

Phase A Report was accepted and the f()llo~ing (jl~cisions concerning the

implementation of Phase B were made by the DistJ:"ict.

1. Plan A was the best overall pl.an for lirainage improvements in

First Creek basin as agreed upon by all concerned parties.

2. Each structure crossing t.he First Crt~~?k drainageway was de-

s igned to accommodate the IOO-yea r flows wi. thout damage. This .was ac-

complished by one of the following methods

a. Where practical, st.l::-ucLures v,'(:,rp designed to pass the 10-

year flows with structural protection for the lOO-year flows.

b. Waterway for railroad ~nd rna(lway crossings downstream of

Station 221+00 were designed to pass the IOO-year flows under

pressure flow conditions without. overtopping. The Buckley Road

crossiug was also designed for LOO-rear flow.

3. Improved channel sectiO[lS Wl"re deslgned to conL1.in the 100-

year flows, with adequate rip rap protect.ion provi.ded wherever n.ece:~sary

for the reach downstream of O'Bri.an CanaL t.o Highway 85 and in the Foul-

ton Ditch reach.

After r.eceipt of the notice to p:coc-2ed vlittl Phase B 7 the following

plan of approach was formulated for compLet.ing the Phase B work:

1. Update and finalize hydr~ology )rE_'pklred in Phase A.

2. Prepare design criteria to be 'lsed in Phase B.

3. Perform hydraulic computati ons and de t.ermine discharge capa-
city of all structures crossing t.he drainaf,e\l!ay.

4. Prepare layouts, reach by rt~acJIJ of' possible channel and

structural improvements using costs of improvements as a guide.

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