FLOOD01619

• Designation Number: 320
• County: Jefferson
• Community: Arvada
• Stream Name: Lower Ralston, Van Bibber, Leyden Creeks
• Title: Major Drainageway Planning
• Date: 2/1/1986
• Prepared For: Arvada
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

SHEET 5 OF 37
COMMENTARY
RALSTON CREEK
STATION 207+00 TO 234+00
REACH R3
CITY OF AR VADA

SHEET 5 OF 37
COST ESTIMATE
RALSTON CREEK
STATION 207+00 TO STATION

CONSTRUCT ION

Residential development encroaches close to the channel banks along the
north side of the channel. Some development has occurred upstream along
the south of the channel. The remainder of the channel is bounded by an
existing park. The floodplain is confined to the channel and approximately
one block outside the channel.

Drainage improvement costs
Street crossing costs
Utility relocation costs

Total construction costs

The channel recommended downstream of Miller is grass 1 ined and capable of
conveying the 10-year flows. Proposed Miller Street improvements consist
of the construction of a bridge spanning this open channel. Upstream of
Mi 11 er Street a tr ans i t i on needs to be constructed to convey flow through
the bridge. Upstream, the channel should rapidly transition into a natural
configuration thereby not disturbing the existing park. These improvements
will require the purchase and relocation of three homes adjacent to the
existing channel.

Engineering and contingencies
(30% of total construction costs)

Property acquisition costs

TOTAL IMPROVEMENT COSTS

MAINTENANCE

On the upstream portion of Sheet 5 of 37, a European lined channel is pro-
posed. These improvements begin at Oak Street with the construction of
four 8' x 14' box cul vert sect ions. Upstream, a European type channel is
proposed to convey the 10-year event. These improvements would require the
purchase of two homesites. Downstream the channel would be transitioned
into the existing park. A low flow channel similar to the existing low
channel should be constructed in order to hasten the reestabl ishment of
riparian habitat along this perennial stream.

Annual operation/maintenance costs

Floodpl ain regul ations should be superimposed on the recommended improve-
ments. This will insure that no imprudent development occurs in the resi-
dual 100-year floodpl ain. Prior to the construction of recommended im-
provements, floodplain management practices should be in accord with the
flood hazards identified for the existing channel conditions.

234+00

$526,589
616,562
33,490

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I
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$1,176,641

352,992

275,150

$1,804,783

$6,991