FLOOD01790

• County: Adams
• Community: Adams County
• Stream Name: Second Creek, Third Creek
• Title: Flood Hazard Area Delineation - Second and Third Creek
• Date: 2/1/1976
• Prepared For: Adams County
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

I
I
I
I
I
I
I
I
I',
I
I
I
I
I
I
I
I
I
I

12

union Pacific Railroad and the U.S. 85 embankments and drainage
structures give rise to potential flood flow diversion from the
Second Creek drainage into the Third Creek drainage. This
increases the peak flow tributary to the Third Creek bridges and
culverts at the Union Pacific Railroad and U.S. 85, resulting in
increased amounts of flood waters diverted further north. Because
of the terrain the flooding is shallow, except near the embank-
ments. It is difficult to access the area of potential flooding
north of Third Creek from these diverted flows. Because of the
flatness of the terrain, the porosity of agricultural fields and
the existence of many road and irrigation ditch embankments along
this northerly flow path, in our opinion it is unlikely that any
of these flood waters will cause damage in the City of Brighton.
Regardless, it is in the best interest of the public to be aware
of such a condition. The three farms in this reach along East
136th Avenue are all subject to flooding by shallow flood depths.
The farm directly below the Fulton Ditch would experience the
most damage from possible breaching of the ditch.

From 1-76 to East 120th Avenue, Third Creek crosses alignments

with four roads, the 1-76 east and westbound lanes, a county

road, Buckley Road; two irrigation canals, the Burlington Ditch

and the O'Brian Canal; and one railroad, the Burlington Northern.

These facilities obstruct the 100-year flood plain and cause

backwater conditions which widen the flood plain. The flood

plain covers an extensive amount of farm land as well as three

small outbuildings downstream of East 120th Avenue.

Above East 120th Avenue to East 112th Avenue, the 100-year flood

plain varies from generally 300 feet to over 1,500 feet in width,

encompassing agricultural fields, bottom lands and a race track,

Drawing TC-20. Two roads, East 120th Avenue and Tower Road, are

overtopped by maximum depths of approximately 1.9 feet and 2.0

feet respectively. An area north and south of East 112th Avenue

near Third Creek is subject to potential shallow flooding from

flood waters diverted from the main channel at the road crossing.

The maximum depth of flow over East 112th Avenue is approximately

4.3 feet.

Above Fulton Ditch to Interstate 76, Drawings TC-9 to TC-13, the
flood plain is wide but confined within determinable limits. The
flooded area is totally agricultural. Three roads would be over-
topped in this reach. They include East 132nd Avenue, overtopped
to a maximum depth of approximately 3.6 feet, South 4th Avenue,
flooded to a depth of approximately 3.1 feet, and a service road
to 1-76, overtopped by less than one foot of water.

Above East 112th Avenue to the Urban Drainage & Flood Control
District boundary, the upper study limit, the 100-year flood
plain limits are well defined and confined primarily to bottom
lands. The creek crosses a county road in this reach, Drawing
TC-26, which will be overtopped during the 100-year flood event
to a depth of approximately 0.9 feet.