FLOOD04002

• County: Jefferson
• Community: Golden, Jefferson County
• Stream Name: Clear Creek
• Basin: South Platte
• Title: Major Drainageway Plan - Clear Creek: Youngfield Through Golden
• Date: 2/1/1982
• Prepared For: UDFCD
• Prepared By: Wright-Mclaughlin Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

'II-J

Tfl~ structural aes igl1 firm of Jorgensen ana Kenarickson conducted a fie 10
survey of the e~ 1st Ing structures and oota i nea a II av ~ i 1 db Ie cons truct i on
ara..il1~s for the bridges. Impact, u~l ift and scour forces were <;alculded by
\/right-McLaughlin Engineers, ana these forces were r~lated to the e~hting
briages by Jorgensen and Hendrickson to determine tneir stability. A summary
of thearag and impact forces mdybe found in Table VI-I. The dllalysis of
the oridges at Ford Street dnd Washington Avenue showed that:

1. Under lOO-year flOOd conditions, tne channel oed is expected to scour to
adeptnof3-feet 10cal\y at Ford Street, while no significant scour is
expected to occur locally at ;/ashington Avenue. In either case, scour
will probably not be severe enough to undermine the existing bridge d but.
ments;

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2. The existing bridges at Fora Street and I-Jdshington Avenue will liKely
sustain damage and possioly loss of tne oridge deck from the 50-yedt <lnd
lOO-yearfloods dS a re.ult of the combination of uplift dnd impact for.
ces and ~ccumulJtjcn of debris juring these events;

3. LOO-yeal" im~act forces can be reduced, out not e I iminat,.a oy the aadit ion
of a second bridge or culvert structure at each location an~ constructing
channel improvements upstream ana downstream of each bridge. DN~ forc~>
c<ln be further reauced oy shaping of the upstream eml of the existlng
bridges. HOwever, such Shaping should flat be installed until the Channel
ca~dcity is enlarged inc Iud ing tne C<Jl verts ment ioneo above. fhis is
necessary to prevent lodging of aebris under the deck during floodstage.

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lJO'l~.'. iil\~.d fo(~e, can be~t be n;inlmH,:d or clb~nJt~c !lJ r1l~ldci~g

the ex ist ing Drid~e d~cks at Ford Street and loIasnington Ayenue with new
bridge decks set at an elevation at least 2 feet above the lOO.year water
surface. Tne 2 feet represents a minimum practicdl free board to allow
foroebrispassage. Tnee,isting bridge abutments are strudurallysound
arid coula be mOdified to sUP,Jort thene'lI bridge deCKS. P.n additional
oridge or culvert structure and Chann~l izat ion would st i II b<1 ~eqI!1~ed at
eacnlocation;

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