FLOOD01357

• Designation Number: 107
• County: Jefferson
• Community: Unincorporated Jefferson County
• Stream Name: Green Mountain Area
• Title: FHAD - Green Mountain Area
• Date: 4/1/1978
• Designation Date: 7/11/1978
• Floodplain - Doc Type: Floodplain Report/Masterplan

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The flood hazards in the reach consist of erosion, debris removal

3. Station 28+00 to 0+00, Urban Street to Confluence (Sheet 27)
The channel in this reach consists of a storm sewer along
Simms Street and a broad V-shaped section traversing westerly across the
open field. The average channel slope is about 2.3~. The storm sewer
consists of a 48 inch RCP and a 38" x 60" HE-RCP in the reach along Simms
Street, which is also the channel for this drainageway, The sewer system
has adequate capacity for the 5 year frequency stJrm. fhe flood in excess
of the storm sewer capacity will flow in the street and the adjacent property.
The 100 year flood for the remaining portion of the reach will be contained
within the broad area of the channel. The channel is crossed by the Agri-
cultural Ditch without provision for passing the Flood peaks across the

The flood plain is generally contained within the channel area
except in the vicinity of the old railroad embankment (Station 87+00),
where the flood waters overtop the embankment and flow across Zang

Street.

and cleaning, interrupted traffic and services, and a low to moderate

life hazard due to the high velocity, moderate depth channel flow.
2. Station 56+00 to 28+00, 6th Avenue to Urban Street (Sheet 26)
The channel in this reach consists of street flow along Vivian
Street beginning at 6th Avenue and proceeding to 8th Avenue, easterly
along 8th Avenue to Van Gordon Court, then northeasterly across the
residential area to Urban Street, The average slope through the reach
is about 5,0%. A 42 inch RCP storm sewer in Vivian Street also begins
at 6th Avenue but continues down Vivian Street across 8th Avenue into
lakewood Gulch. The storm sewer intercepts a portion of the storm runoff
in Vivian Street, but the flow in the pipe is controlled by the runoff
from the basin above 6th Avenue. The channel has an average slope of
about 5% through this reach, and is crossed by the Welch Ditch (Station

ditch.
The flood hazards in the reach consist of erosion, debris removal
and cleanup, interrupted traffic and services, and a low life hazard due
to the shallow flooding.

The flood hazards in this reach consist of debris removal and cleanup,

F. Drainageway F
Drainageway F is the upper reach of lakewood Gulch which drains the

northeast flank of Green Mountain,
1. Station 20+00 to 0+00 and Station 546+00 to 533+00 U stream
Study limits, to Vir inia Drive (Sheets 28 & 29
The channel in this reach has been designated Drainageway F and
F-l, a minor tributary. The channel consists mainly of broad, shallow
overland flow on the steep slopes (10 to 20%) of Green Mountain, A
portion of the designated channel follows along Gardenia Street. The
flood plain generally remains confined within a limited area with shallow

high velocity flow.

49+00) .

deterioration of the street, structural and content damage to the residences,

and a low to moderate life hazard due to the shallow high velocity flooding,

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