FLOOD02900

• County: Adams
• Community: Commerce City
• Basin: South Platte
• Title: Lower First Creek and Direct Flow Area 0055 Major Drainageway Planning
• Date: 5/1/2002
• Prepared For: UDFDC
• Prepared By: Turner Collie & Braden Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

DFA 0055

. Direct Flow Channel. Provide a grass-lined channel with 1 OO-year capacity from Belle
Creek development upstteam under 1-76 to the confluence of Arsenal North and UPRR
Tributaries. Provide crossing structures for the IOO-year discharge at 104'" Ave., US 85
and 1-16.
. Arsenal NOrlh Drainage. Provide a grass-lined channdwith 100-year capacity from
Dire-ct Flow Channel upstream to the Rocky Mountain Arsenal, following [he alignment
depicted on Figure 8.. page iii, of Report. Provide crossing structures for the IOO-year
discharge at the UP Railroad. Burlington Di:ch, O'Brian Canal. Havana. SH 2 and 95'1
Ave.
. Elm Drainage. Provide a grass-lined channel with lOO-year capacity from Arsenal North
Drainage Channel upstream to the Rocky MowllainArsenal, following the alignment
depicted on Figure B, page iii, of Report. Provide crossing structures for the IOO-year
discharge a.t 96" Ave. and SH 2.
. Union Pacific Tributary_ .Provide a pass-lined channel with I OO-year capacity from
Arsenal North Drainage Channel upsrream to 96'h Av~., following the alignment depicted
on Figure 8, page iii, of RepOrt. Provide a crossing SIt1lcture for the lOO-year discharge at
96'h'Ave., .
. Rolla Tributary. Provide a grass-lined channel with IOO-year capacity from Arsenal North
Draill2ge Channel upstream to 96'h Ave.. following the alignment depicted on Fi~ure B.
page iii. of Report. Provide a crossing structure for the IOO-year discharge ar 96' A vc:.
. Birch Tribulary. A grass-lined channel with lOO-year capacity has been consrrucrcd
parallel to Dallas St. Provide a crossing structure for the lOO-year discharge at 96'h Ave.
. What lype of grass-lined channel do we want?
. Optimize crossing structure type (bridge vs. culvert) ilnd dimensions.
. Recommend noodplain management of the IOO-y::ar floodplain based on fiJIly developed
(i.e., future) land use projections a5 a minimum, until channel capacities are increased or
I OO-year discharges are decreased. Then manage the residual floodplains.

"This drawing is for master planning purposes and represents preliminary and
concepr'lal engineering. Alternatives ro rhis outfall S) 'stem wiff be considered by
local agencies and Ihe Urban Drainage and Flood C{.ntrol District provided the
alternative offtx! an equivalent hydraulic capacity and stream stability, The
alternative must comply with all requireml!nts of rhe 1.?Cal jurisdiction and the
Uroan Drainage and Flood Contra! District. This drawing shalt not be usedfor
construction purposes. III addition. there may be State and Federal requiremenrs
. that will need to be considered ond met. This drawing is not 0 flno! design ond
shall nor be usedfor constnlction purposeS. "

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
1
I

floodplain from SH2 to 96th Ave. Provide crossing Slnlctures for !he detained 1 CO-year
discharge ,at SH 2 and 96<10 Ave. Consider relocating Peoria St to the lop of the proposed
Maul R~er-'oir embankment Items to be considered include the added embankment
width required for a road and how a spillway worles ~ith a road.
. Optimize crossing strUcture type (bridge vs. culvert) and dimensions.
. Recommend floodplain management of the IOO-year tloodplain based on fully developed
(i.e., lUture) land use projections as a minimum, until chann~1 capacities are increased or
IOO_year discharges are decreased.

Commerce City; Provided Review and Input. Or X)(X."'( attended progress meetings and
,provided the following input:~.
. lnclude a specific section in the repon which discusses the best way to phase
irnpl'ementation to achieve the greatest benefitS at the earliest possible time. This will
include, but nOI be limited to, early implementation of Maul Reservoir to be used initially
for more frequent events and water quality; and later for 1 OO-year peale flow reduction.
. Channel right-of-way should be clearly delineated on the drawings included in the
Preliminary Design Report.
. A maintenance-access trail or route should be shown along all outfalls and drainageways.
To the extent feasible, the alignment of these trails should be coordinated with existing
and planned recreational trails identified using input provided by Commerce City and
Adal"t1S County park departments.
. Report cost estimates of improvements based on the j'llisdiclion where those
improvements are located'as well as in which reach. '
. Unit costs should be updated to reflect the most current costs available.
. Report cost estimates for maintenance of detention facilities, channels, and Storm sewer
systems in the preliminary design.
. Show these 'notes on each sheet of the drawings:

"Adams County and Commerce City manage and reg;l/ate all land use change.
development Clnd red<?Ve!opmenr activities within the .'OO-year floodplains in order
10 preventfurureflood damages to buildings and stru,~t!lresfrom the IOO-year
flood to a mCL,imum extent possible, and to minimize dal7lr;rgesfrom larger floods.
The recommendariol'lS of this plan provide a set of options subscribed to by Adams
COflnry and Commerce City in carrying out their floodplain monogemenr and
regulatory respo1'\Sibiliries and obligarions. ..

ADlllTJONAL DlRECTIO:\'

EXECUTIVE SUMj'.l"ARY

The following additional information should be included in th: final report.
. Include an Acknowledgemems section listing all participants in the planning study.
Include in the list their narne, organization and function in the planning process (e.g.,

Include an Executive Summary in the Preliminary Design Report. Direct this summary at the.
. general public and elected officials. This summary should, at the minimum, contain:
. A brief summary of the planning process including the numbers of progress and public
meetings.

Sdccld PI,,: Lower Firsr C,~.k ~aur.,I"d 2

StltCl~d Plan: Lower FI,.<r Creek W"te,shed 3