FLOOD10386

• County: Jefferson
• Community: Golden, Lakewood
• Stream Name: Upper Lena Gulch
• Basin: South Platte
• Title: FHAD - Upper Lena Gulch
• Date: 1/1/1993
• Prepared For: UDFCD
• Prepared By: Boyle Engineering Corporation
• Floodplain - Doc Type: Floodplain Report/Masterplan

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buildings located along the campground.

damage is expected to the permanent

Damages In

100-year flood

reach are due to erosion and pavement overtopping

Consequently, Zeta Street is overtopped during the

this

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if the campground is fully occupied with

Additional damages would be expected

recreational vehicles when a flood occurs

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Sta. 396 + 50 to 414 + 70: Sheets 3-4

L-11

The channel

long culvert discharges Into a small natural channel

The 600-foot

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the Amoco Gas

and

Street

West

the vicinity of

crosses under two driveways In

residential properties and a

commercial and

reach contains a mixt4re of

This

reach is

portion of this

the lower

floodplain In

The

Station on Highway 40

culvert is

the Zeta Street

from

Flow discharging

facilities

drainage

range of

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the area

at

the south, except

generally contained by U.S. Highway 40 on

this portion of the

to

Adjacent

conveyed along an artificial channel section

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flow

The

the Amoco Gas Station where Highway 40 is overtopped

adjacent to

retain the high banks

retaining wall has been constructed to

channel. a concrete

to an undersized

constriction at the eastern Amoco driveway, which occurs due

wall extends

This

bank overtopping

to prevent

floodwal

as a

to act

and

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flow calculation
from

A weir

the south

Highway 40 to

culvert. causes overtopping of

culvert.

of the Zeta Street

the outlet

from

downstream

150-feet

approximately

main

the

ost

approximately 40 cfs is

that

to determine

was performed

the wall is

important that

is

it

this wall, and

is contained by

imit

floodplain

The

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main

the

to

path unrelated

it re-enters the main channel downstream

follows an independent

flow

The lost

channel profile. unt;

channel

the

to

side of the wall and

the east

maintained in order to prevent flooding on

north of Highway 40

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Sheet 4

Sta. 385 + 00 to 396 + 50

L-10

the channel makes a 90-degree bend to the

At the end of the concrete floodwal

relatively

and enters an unimproved channel section which has experienced

severe erosion problems

east

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the channel is

mmediately downstream of the Amoco Gas Station driveway

The banks are heavily scoured and evidence of bank

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two

been encroached by

The channel has

unimproved and undersized

readily visible

sloughing is

and is heavily

Street

Violet

upstream of

reSidential/commercial structures just

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reach is

this

through

floodplain

the

n spite of this debris

obstructed by debris

long

an approximately 600-foot

flows enter

Downstream of this channel section

to

is of adequate capacity

Street

Violet

The structure under

relatively narrow.

inadequate capacity

concrete box culvert. This box culvert is of

5-foot by 8-foot

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1 OO-year flow.

convey the

through

The culvert alignment is

overtopping

without

10-year event

the

even

for

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Discharge in

Tincup Village Campground along U.S. Highway 40

the East

the campground and is conveyed

nundates

the culvert capacity

excess of

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4

Some. structure and content

flow

relatively shallow overland

in

downstream

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