FLOOD00479

• Designation Number: 575
• County: Douglas
• Community: Douglas County
• Stream Name: Plum Creek and East Plum Creek
• Title: FHAD - Plum Creek and East Plum Creek
• Date: 9/3/2004
• Prepared For: Doulgas County
• Floodplain - Doc Type: Floodplain Report/Masterplan

][ (C(Q)N
- ~. - .
ENGINEERING INC
,

ii1
e

I
I
I
I
I
I
I

Design
I .
.. ..
, '-!oil'
...~~~. '
L0'..
'''','
-.'-'
ManagEment:

bOO 5 f'l.;ron Way, StE 300, ErgI~lOOOd, COdOlC: F'h~ 303-ccl-OOOc Fa,,; 303-cCl-40f9

Additionally, as you are aware, we have provided this infomlation to the Colorado Water
Conservation Board (CWeB) DFIRM contractor so that it may be incorporated into the upcoming
DFIR..\l for Douglas County.

August 9, 2004

We ,,,'ouId like to thank the staff of UOFCD and Douglas County for their assistance and
contributions to this FIlAD report. It has been a pleasure to be involved in the Plum Creek and
East Plum Creek FIIAD. and \I,:e look forward to continuing our working relationship with the
District.

ICON Enain('cring Inc. .>&\"",\lliI1ll'U/U/111.
... -' '""""':\\.,.1;)0 RfC//!'IQIl
;::,</::o"~~ ....... "l"oL'::~
d), . f ~~..(}.S J. W~...1=l^
~ElJ' } /JdL fJ:2 ",",0.
tI. . 0. W~'{o 23599 ~ll
Douglas . Wi' s. P .E. '\ 1;... ..~ f
P' , I I Ch ~ ~.. .._-&; ~
nnclpa - n. arge ~ eSS.......... ~\~ ~~
"'~...~i'ONAl (\\ 1<.\\~-:-
"'lJ~/IIMIlI1I\\\\\'

f\.'fr. Bill DcGroot. P.E.
Manager. Floodplain .\lallagement Program
Urban [)raina~e and Flood Control District
2480 \Vest 26 Avcnue. Suite 15613
Den\'er, CO 80211

Sincerely.

Subjcct:

Flood Hazard Area Delineation for Plum Creek and East Plum Creek
UDFeD Agreement No. 03-10.07

Dear Bill:

ICON Engineering, Inc. is pleased to submit the attached Flood Hazard Area Delineation for Plum
Creek and East Plum Creek, dated August 2004. Thank you for providing comments on our draft
submittal. All of your comments have becn addressed at this time. Along with this lettcr, we have
provided 50 original copies of the FHAD n:port, a bound technical appendix, and full.size mylars
of the plan sheets and profile sheets.

~'L)

Craig D. Jacobson. P.E.. C.F.M.
Project }"'Ianager

This study identifies nood pronc areas along Plum Creek and East Plum Creek within portions of
unincorporated Douglas County and the Town of Sedalia from approximately 4.000 feel upstream
of Airport Road on Plum Creek to just upstream of the UDFeD boundary on East Plum Creek.
located approximately 1.000 feet upstream of the Burlington Northern and Santa Fe Railroad.
^ 3.2 mile reach was studied on Plum Creek and a 3.6 mile reach was studied on East Plum Creek.

tl~,/j:;

Project Engineer

The floodplain infonnation included in this report is provided by the UDFCD to assist Douglas
County in Iloodplain management and regulation along Plum Creek and East Plum Creck.

The report provides documentation and drawings idcntifying the 100-year floodplain limits, 10- and
100-year \',;ater surfacc profiles, representati\'c channel cross sections and major road crossings.
Tabular information is included showing floodplain data and noodway information based on both a
D..5-foot and 1.0.foot maximum rise in energy grade line.

For this project. hydrology \Vas taken from the 1996 Flood Insurance Study for Douglas County.
ChaJUlel cross-sections Weft~ developed from 2-foot contour aerial mapping provided by Landmark
l\lapping. Ltd.. Bridge dimensions and "-Ianning"s "n" values were determined by field
measurements and observations by our staff. Please notc that the Rio Grande A \"Cnue Bridge is
currently undergoing reconstruction. The Iloodplain sho\\TI by this report rellects the existing
structure in place. The construction of the new bridge may result in changes to the Plum Creck
floodplain.