FLOOD03286

• County: Adams
• Community: Wheat Ridge, Arvada
• Stream Name: Lower Clear Creek
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 10/1/1981
• Prepared For: Adams County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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-2-

V-2

Major Drainageway Planning
for
Lower Clear Creek

imately 800 feet downstream of Federal 81vd. and extending upstream to Reach
lIB.

SELECTED PHASE B PLAN
February 27, 1981

4. An enlarged crossing at Pecos that meets the overtopping criteria for
arterial streets. If the cost of meeting this requirement is excessive,
work with Adams County and District to determine what may be reasonable
to plan.

REACH lIB (1400' u/s of D&RGW to Wadsworth)

GENERAL

The Phase B report and preliminary design shall be based on the selected plan
that includes the following:

1. Recommendation in the plan to enforce the 100-year floodplain regulation.

2. A discussion that clearly points out the need for regulating a residual
100-year floodplain that may remain after the plan is implemented. Also
point out that the existing 100-year floodplain has to be regulated until
it is modified by physical changes to the existing Clear Creek channel
and its structures. Planning for, or anticipating such chanqes does not
justify regulating anything other than the floodplain defined using existina
channel conditions.

1.

A recommendation for floodplain regulation and floodplain storage preser-
vation in non-channeled areas.

2.

The incorporation of the Colorado Department of Highway's improvements to
channel and bridges between Reach IIA boundary and Lowell Blvd., between
Tennyson Street and the vicinity of 52nd Avenue, and between Marshall Street
and Wadsworth Blvd.

3.

Provide for enlarged cross.ings at Tennyson and at Lowell that meet over-
topping criteria (i.e., not to exceed 18-inches) for collector streets.
The needed enlargements will also need to recognize the increased flow thru
these bridges as the result of any increased flows due to the Colorado
Department of Highways' channel improvements upstream (i.e., reducing the
proportion of flow that would normally be conveyed in the floodplain north
of tne new 1-76 embankment).

3. Encouragement of the purchase of flood insurance.

4. A provision for an adequate maintenance access to all reaches. Any mainten-
ance trail should have a minimum flat surface width of 10 feet.

REACH IlIA (Wadsworth to 800' u/s of Kipling)

5.

1. A recommendation for floodplain preservation.

A provision for adequate erosion control for all channel improvements and
structures.

Recommend that new development in the basins provide on-site erosion control
durin~ construction to limit the amount of silt and earth washed into the
creek-during normal (frequently Occurring) runoff events.

Restrict the use of floodplain for land fill operations.

6.

2. New 100-year bridge at Kipling Street.

3. A total of 1800 feet of channel improvements in the vicinity of Kipling

Street.

REACH IIIB (800' u/s of Kipling to 1-70)

7.
8.

A recommendation to develop a flood warning system.

1. A recommendation for floodplain preservation.

REACH I (Confluence with the South Platte River to Huron Street)

1.

Removal of a "bottle neck" constriction in the channel near South Platte
River.

A recommendation for floodplain preservation.

A recommendation to enlarge Broadway Avenue crossing to meet overtopp~ng
criteria for arterial streets. If the cost of meeting this is exceSSlve,
work with Adams County and District to determine what is reasonable to plan.

REACH IrA (Huron Street to 1400' u/s of the D&RGW R.R.)

2.

3.

1. A recommendation for floodplain regulation and floodplain storage preser-
vation in non-channeled areas.

2. New 100-year bridges at Federal Blvd. and the D&RGW R.R.
3. Approximately 3500 feet of rock-lined 100-year channel starting approxi-