FLOOD10485

• County: Arapahoe
• County: Douglas
• Stream Name: Big Dry Creek
• Basin: South Platte
• Title: Big Dry Creek ‎(Arapco)‎ & Tributaries - Major Drainageway Planning - Phase B Preliminary Design Report
• Date: 4/1/1998
• Prepared For: Arapahoe County, Douglas County, Englewood, Greenwood Village, Littleton, UDFCD
• Prepared By: WRC Engineering, Inc.
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

ES-2

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a

1 OO-year period

it

was estimated that the average annual

probabilities
flood related costs to replace houses and contents

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Big Dry Creek in this reach

After accounting for various

of flood damage occurrences over

public meetings adamantly opposing any improvements to the stream crossings and any channelization of

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The areas of greatest concern are as follows

to upstream of Franklin Street.

Numerous comments were

s the reach of Big Dry Creek from Orchard Road
received from a number of local

residents at the

water quality, and safety concerns

One of the most discussed and debated segments

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are currently eroded and sloughing into the channel causing loss of property,

sedimentation,

improvements and associated schematic drawings

were developed for 24 separate channel reaches.

.

Of the total approximately 20 miles of drainagcway, almost three miles of channel banks

then compared to the relative risks of making only minor or no improvements

A complete

list of alternative

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event.

enlargement
alternatives

were prepared for specific channel

of Big Dry Creek's channel, and various

reaches to give a range of possible improvements that

major and minor structural improvements

Several

were

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.

Over 30 homes, businesses, and a church are expected to be flooded during a I OO-year flood

nothing

These alternatives,
alternative

(status quo) to bio-stabilization of channel banks, to

vary
large bridgc replacements and

summarized

in Chapter

VI

and detailed in

the Phase

A

report,

from

in this study.
'do

the

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of public

mprovements at risk.

A variety of alternatives

to address

floodplain problems identified

flooding of the roadways
road surface for over one or

more hours during such a flood. This places millions of dollars

were examined

Many ofthcse crossings

undersized and incapable of conveying the

Nineteen ofthe twenty-seven street and road crossings on Big Dry Creek and tributaries are

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100-year flood peak without overtopping and

have flood waters crossing over the

Chapter V of the report.

problems and problem areas,

including the above three areas, are summarized in detail

Other drainage
in

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.

Recreation Center's parking lot

and also risking a total

DcKoevend Park causing flooding ofthe Goodson
breach of the canal

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Denver Highline Canal

is ovcrtopped at

sewers,
conducted for this study.

The results of this analysis showed the following:

Dry Creek Road (2.0 miles upstream). Just downstream of South University Boulevard, the

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sanitary

roadways,

etc.) at

greater risk of failure

A detailed analysis of drainage problems was

of Big Dry Creek not under water wi

be South Broadway (3.5 miles downstream) and East

the channel

causing erosion and sloughing of channe

OO-year event or greater;
banks

which places

public improvements (i.e. trails,

impassible for up to an hour or

more

Should that happen,

the closest available crossings

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potential flooding of homes,
which wi

be

impassable during a

and problems associated with

degradation of

arc expected to overtop both South University and Arapahoe

In addition,
Road

such that they may be

include

businesses, and a church: a relatively large number of roads and streets

Several significant problem areas exist along Big Dry Creek's channel

The most significant of these

homes and a church are within the

OO-year floodplain

OO-year

area,
flood waters

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398
387
374
337
278
240
162+174/176
52

S. Platte River
Broadway
Orchard Road
Arapahoe Road
Dry Creek Road
County Line Road
University Boulevard
Quarry Road

12,600
12,600
12,600
11,800
] 1,800
10,900
10,900
3,800

6,50

8,895
8,878
8,491
6,538
4,413
3,558
(Tn)! I ,600
2,115

.

Big Dry Creek in the South UniversityfDenver

Highline Canal area.

In

this

eight

(Out)

the Big Dry Creek channel during the

OO-year flood.

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portions of the City of Englewood's

overtopped by
Water Treatment Faci

ity are affected by flows

leaving

floodplain.

In addition, South Santa Fe Drive

s

OO-year peak flows and

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reach, over 35 acres of commercial

and

upstream of Windennere Street.
industrial

land

s

located

within

the

OO-year

VTN (1975)
(cfs)

WRC (1995)
(cfs)

.

Big Dry Creek from

the South Platte River to lust

In this

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WRC
DESIGN
PT

LOCA nON

feet in depth

area are undersized. The

OO-year flood

is estimated to overtop these streets by two to five

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00- YEAR FLOW

PEAK RUNOFF COMPARISONS

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homes are within the 1 OO-year floodplain. In addition, the three public road crossings in this

Big Dry Creek from Orchard Road to Upstream of Franklin Street.

In this reach, fourteen

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