FLOOD00689

• Designation Number: 136
• County: Arapahoe
• Community: Littleton
• Stream Name: Slaughterhouse Gulch
• Title: Major Drainageway Planning - Slaughterhouse Gulch, Littleton
• Date: 5/1/1974
• Designation Date: 5/1/1979
• Floodplain - Doc Type: Floodplain Report/Masterplan

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SECTION XII

SUMMARY AND CONCLUSIONS

The preliminary plan developed for Slaughterhouse Gulch repre-
sents the culmination of extensive hydrologic, hydraulic,
economic and environmental studies on the drainageway. The
study reach extended from the mouth of the gulch at the South
Platte River to Powers Park on the main stream and along the
South Tributary to Slaughterhouse Gulch at its confluence
with the main stream to Datura Street near Littleton Boulevard.
The study was initiated by the City of Littleton and funded in
part by a comprehensive planning grant awarded by the Depart-
ment of Housing and Urban Development through the Denver
Regional Council of Government and in part by the City of
Littleton.

The study reach as defined above covers approximately 1.2 miles
on the main stream and approximately 1/2 mile on the South
Tributary. At the mouth, the basin drains slightly over two
square miles of a totally developed urban area. Flood hydrographs
were computed at various points along the study reach for the
two, five, ten and 100 year storm frequencies.

Flood plains were computed for each of the storm frequencies
indicated above to provide a basis for further study and eval-
uation. The flood plains were computed utilizing the Corps of
Engineers HEC-2 Water Surface Profiles Computer Program. The
Slaughterhouse Gulch flood plain was represented in the computer
program using sections taken from the mapping completed on the
gulch, as well as various coefficients and energy loss factors
which represent the full range of hydraulic conditions charact-
eristic of the gulch. .

The damage analysis was completed to ascertain the cost of
flooding associated with the gulch. The cost is indicative of
the expense incurred by all parties affected by the flooding,
both public and private. The damage evaluation considered pre-
sent day channel conditions as well as the'existing degree of
development. The average annual damage cost through the. study
reach for both direct and indirect costs was calculated to be
approximately $373,410: per year. Approximately 2/3 of this
cost was attributed to the flooding situation on the South
Tributary.

The study was undertak.en..'to evaluate possible alternatives and
various plans for eliminating these flood damages. During the
interim planning process, three alternatives were schematically
proposed and evaluated.,' ;,The three alternatives were then sub-
mitted to the City for further evaluation and selection of a
final approach to be evaluated in greater detail. The selected
alternative proposed culvert and channel improvements in the

XII -1