FLOOD05661

• County: Adams
• Community: Cities of Federal Heights, Thornton
• Stream Name: Niver Creek
• Basin: South Platte
• Title: Drainage Study
• Date: 2/1/1974
• Prepared For: Federal Heights, Thornton, Adams County
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

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lined channel was not feasible due to excessive velocities (10 fps at 100-year
flood flows); therefore, riprap lining is recommended.

The estimated cost of modifying this reoch to contoin the 100-year flood

proved the scheme to be economical compared to the high damage potential.

Very little maintenance will be required in this reach except for cleaning

out debris which collects on the boffle blocks of the drop structure,

Explorador Calle Crossing

The existing bridge opening has a discharge capocity of 880 cfs which is
less than the 10-year flood flow of 1,250 cfs, Raising the bridge to increase dis-
charge capacity would be difficult and expensive. Examination of construction
drawings of the existing bridge indicated that the channel beneath the bridge could
be widened to increase the discharge capacity to 1,900 cfs. This would result in
sheet flow over the bridge during a 100-year flood; however, almost 011 of the
overflow wi II return to the channe I.

Explorador Calle to Washington Street - Plates 111-5 and 111-6

Channel Design

The channel in this reach is contained in a corridor known as the Coronado
Parkway, bounded by Coronado Parkway on the north and East S3rd Drive on the
south. The existing chonnel is concrete lined for a height of 3,5 feet above the
channel invert. The channel drops approximately 28 feet in a length of 2,980
feet or 9,5 percent. The existing channel shows no apparent sign of damage due
to the M:Jy 5, 1973 flood.

The land adjacent to the creek in this reach is fully developed with
single- and multi-family dwellings except for a 900-foot reach to the south of
the creek immediately east of Washington Street.

111-6