FLOOD09740

• County: Boulder
• Community: Boulder
• Stream Name: Sunshine Creek
• Basin: South Platte
• Title: Major Drainageway Planning Volume 1, Part A
• Date: 9/1/1969
• Prepared For: Boulder County
• Prepared By: CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Mr. Andy ~riscoe
3 September 1969

Page 3

lying west of 4th Stteet. The flood plain is shm-m on sheet 1. Follow-
ing construction of the proposed improvements, the flood plain I-Ii 11 be
confined to those areas included within the flood plain on sheet 2.

Uesign Criteria

Design Criteria for this Master Plan is based upon the ~rban Storm
Urainage Criteria Manual of the Denver f(e9ional Counci I of Governr.lents.
Some variation vidS made, hO\;Jever, to account for the need to carry sedi-
ment through the proposed channel because of the unique character of
this particular gulch.

Specific notes regarding design criteria and additional investi9ations
which should be made prior to design, are presented on sheet 2. It
should be noted that '-Jhere riprap is shmm, final design may properly
sho" rockfi lied gabions, grouted riprap or regular riprap, Furthermore,
whether or not gravel base for the riprap '-J; 11 be requi red, f'l"st be
determined from detai led field investigations.

It should also be noted that extensive use -has been made in tile rlaster
Plan of rai Iroad tie retaining "ails. Final design r.lay indicate other
types of aesthetic retaining lIall r,'aterial ,.till be Clore suitable.
Furthermore, use of railroad tie retai:ling '.;falls '.-lith aJequ..1te tie-backs
should receive additional design studies to insure its compatibility "Jith
the velocity of the flood flailS.

The channel betl-Ieen Canyon Street and Pearl Street is based upon steeply
sloping CO:lcrete '-I a 1 Is for both banks. This design concept is utilized-
extensively in the old historic cities of Europe successfully. ilo',lever,
there the concrete is faced \>Jj th rock to increa'le the rougl1nes~ and to
present an appearance corapatibJe ~.Jitrl the surrounding erlVirOfH!lent.

The Ilaster Plan

The f1aster Plan for Sunshine Gulch, as shOlm on Sheet L, is desiyned
to carry 1,000 cfs ~.Jithin the floodvJay. There i:, an arlific..ial flood
channel from the confluence with Boulder Creek to a point approximately
200 feet north of Spruce Street. Above this. the t1aster Plan consisb
of cleaning and clearing the channel along "ith mioor landscaping to keep
the flood ~Jaters from flo\-Jing a\oJay fror.] Sur.shine Gulch. bel'.,1een tile
Farmers Uitch and Pearl Street, the channel is designed to be compatible
with surrounding future uses. The Ctlannel bet\leen Fearl and Canyon, through
an industrial area, "Jill consist of a higher velocity channel. The channel
crOSS sections are viewed looking. downstrear:.