FLOOD02223

• County: Arapahoe
• Community: Littleton
• Stream Name: Upper Slaughterhouse Gulch
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 3/1/1983
• Prepared For: Littleton, Arapahoe County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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CHAPTER I - INTRODUCTION

The Phase-A report was completed and submitted to the UD&FCD on July 21, 1982,

Notice-to-proceed On the Phase-B study was given October 18, 1982, (Appendix-A),

PHASE-B
I, Finalize hydrologic and hydraulic studies,

A, Authorization

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This study, covering the storm drainage aspects and major drainageway planning

for Upper Slaughterhouse Gulch was authorized under the terms of the contract

between Urban Drainage and Flood Control District (UD&FCD), the City of Littleton,

Arapahoe County, and Water Resources Consultants, Inc, (WRC), dated December 18,

1981, The notice-to-proceed was given January 7, 1982 for the Phase-A study, and

October 18, J982 for the Phase-B study, Mapping of the basin was done under a

separate contract between the UD&FCD and Landmark Mapping Company, Additional

Flood Hazard Area Delineation from Euclid Avenue to Arapahoe Road was authorized

by Purchase Order No, 01023, dated April 22, 1982, Additional Phase-B planning

from Euclid Avenue to Arapahoe Road was authorized,

2, Prepare preliminary design of the selected alternative plan in adequate

detail to allow for future planning and design of bridges and culverts,

to permit acquisition of needed channel right-of-way, and to permit

planning of new subdivisions.

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3. Prepare detailed cost estimates of the proposed improvements,

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4. Prepare final report and drawings showing the plan and profile of the 100-

year floodplain under existing and improved channel conditions for future

development flows.

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C, Mapping and Surveys

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B. Purpose and Scope

Contour maps of the study area were prepared by Landmark Mapping Company under

a separate contract with the UD&FCD. The maps were prepared at a scale of I" = JOO'

with 2-foot contour intervals using photogrammetric techniques from aerial photos

of the area taken November 10, 1981, The maps utilize USGS datum and generally

portray the actual ground elevation within J-foot,

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The study was divided into two parts, Phase-A and Phase-B. The Phase-A and
Phase-B study objectives were defined as follows:

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PHASE-A
1.

Evaluate hydrological and hydraulic aspects of the storm drainage in the
Upper Slaughterhouse Gulch drainageway,

Cross sections of the drainageway defined by the engineer were digitized and

used in the floodplain delineation. Additional cross sections were obtained by the

engineer directly from the topographic maps, Additional spot elevation surveys were

performed by the City of Littleton.

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2. Define and assess flood damages and hazards for the 2-, 5-, JO-, 50-, and
100-year storm,

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3. Develop and evaluate a matrix of drainageway improvements to alleviate
flooding problems.

Horizontal and vertical control points used in the mapping are shown on thl'

maps. Permanent monuments were established in the field for purposes of future

reference.

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4. Recommend a specific alternative to the sponsoring agencies and the basis
of engineering feasibility and economic evaluation.

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5. Prepare the Phase-A report.

Existing utilities and improvements in the study area were located from con-

struction and as-built drawings obtained from the Denver Blue Stakes Center, Little-

ton, Englewood, and Arapahoe County.

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