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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RONALD C. MCLAUGHLIN

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WRIGHT.MCL.AUGHL.IN~ ENGINEERS
ENGIN~ING CONaUL.TANT.
20S. ."YANT STIIlI:1!T
DEt\lVUt. COLDlIIIADO SOIII
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.,UlYING . . .
MUNICIPALITIES
INDUaTItV
WATIUt AND S"HIT"TlOH DlaTltlCTS

3 September 1969

WATIII .V....L'I",...ND DI.Tf".UTIOH
WATE" Ttn.AT"I:NT WOIIIKS
.II:W...OI: COLLI:CTION AND OI...08AL
INDUSTIIlIAL. W....TE.
aTO"" 0.....'''''...01: ""CIL.'TII. ANO-
OTHIR WATIE:Jl1 Oltl1!NT1!D ....OJICT.

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Mr. Andy Briscoe
Director of Public \,orks
Municipal Building
Boulder, Colorado 80302

Dear Mr. Briscoe:

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In accordance wi th the proposal for Prel iroinary /1ast.r Planning
for Lower Sunshine Gulch, dated I July 1969, IVe have undertaken
the necessary hydrologic and hydraul ic studies and have performed
the field and office investigations necessary to complete the
assignment. Enclosed in the back of thi, report are 2 drawings,
the first of I-Ihich presents the flood plain of Sun",ine Gulch for
the 100-year flood under existing conditions. The second dral-ling
presents the proposed Master Plan for channel rehabi i itatian of t:,e
Gulch from a point dOvmstream of the existing Famers Uitch siphoc.

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Sunshine Gulch drains a 1.9 square mi Ie basin in the fooH'i 1I,..:est
of Boulder and flO\,s into Boulder Creek at approxi::alely Second Street
and Canyon Boulevard. The study area lies in the:; 1/2 of Section 25,
and the II 1/2 of Section 36, TO\mship I :lorth, I:ange 71 West. Nearly
the entire drainage basin lies in Boulder County, outside of the City
Limi ts.

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You wi II note from Orawing S-I that the old city yarJs at 3rd and
Pearl Streets are presently in the flood plain of :un~hine Gulch. But
undertaking the improvenents indicated on Dra"ing S-=. the 11oodil1g of
Sunshine Gulch wi II be controlled and the city yard. wi II no longer be
in the flood plain.

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Several alternate plans were prepared and discussed with personnel
from your staff before deciding upon the plan presented on Sheet 2.
The alternates investigated and not chosen consisted of an underground
conduit and variations of a high velocity channel, as \'l/el1 as a wider
grass-Jined channel of low velocity_ It was concluded on the basis of
cost, environmental design considerations, and rigllt-of-lVay require-
ments, that the alternate shown on Sheet 2 should be chosen.

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