FLOOD10493

• County: Adams
• County: Arapahoe
• Community: Aurora
• Stream Name: Upper Box Elder Creek
• Basin: South Platte
• Title: Upper Box Elder Creek Outfall Systems Planning Study - Alternative Evaluation Report
• Date: 12/1/1994
• Prepared For: Aurora, Arapahoe County, Adams County, UDFCD
• Prepared By: CH2M Hill
• Floodplain - Doc Type: Floodplain Report/Masterplan

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3.6.5 Retention Storage Losses
3.6.6 Infiltration Losses ....
UDSWM2 Modelling . . . . . . . . . . . . . . . . . . .
3.7.1 Conveyance .Element Identification Number
3.7.2 Stream Geometry . . . . . . . . . . . . . .
3.7.3 Roughness ......................
3.7.4 Routing Connectivity. . . . . . . . . . . . . . .

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.8.1 Baseline Peak Flows, Hydrographs, and Runoff Volumes
3.8.2 Comparison to Previous Studies ..

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3.8

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Alternative Evaluation Report

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upper Jjox ~laer l;reeK
Outfall Systems Planning Study

Contents

Section

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Stormwater Problems and Opportunities
4.1 Flood Impacts. . . . . . . . . . . . . . .
4.2 Stream Stability .............
4.2.1 General Stream Response . . . . . . . .
4.2.2 Assessment of Stability Based on History
4.2.3 Summary.
4.3 Riparian Resources
4.4 Water Quality. .

4.0

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Introduction ....
1.1 Authorization
1.2 Purpose. . . .
1.3 Scope of Work
1.4 Mapping. . . . . . . . . . .
1.5 Background Information .
1.6 Project Advisory Committee
1.7 Study Goals and Objectives
1.8 Alternative Development Process
1.9 Acknowledgements... .

1.0

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Alternative Formulation . . . . . . . . .. .
5.1 Formulation of Alternative Concepts .
5.2 Preliminary Screening of Alternative Concepts
5.3 Refinement of Alternative Concepts. . . .
5.4 Development of Alternatives 1 through 6

5.0

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Evaluation of Alternative Plans
6.1 Basis of Evaluation .. . .
6.2 Probable Capital Costs . . . . . . ..
6.3 Hydrologic Impact of Alternatives
6.4 Qualitative Evaluation of Alternatives

6.0

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Study Area Description ........
2.1 Topography and Physiography
2.2 Soils. . . . . . . . . . . . . . . .
2.3 Surface Water Resources ..
2.3.1 Stream Characteristics
2.3.2 Reservoirs .....
2.3.3 Diversions .....
2.3.4 Flood History . . .
2.4 Vegetation. . . . . . . . . .
2.5 Watershed Imperviousness

2.0

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7.0 Recommended Alternative .......
7.1 Recommended Alternative Plans
8.0 References

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Baseline Hydrology Analysis
3.1 Major Watersheds ...
3.2 Subwatersheds. . . . .
3.3 Streams. . . . . . . . . .
3.4 Hydrologic Models ..
3.5 Rainfall. . . . . . . . . .
3.5.1 Criteria .....
3.5.2 Rainfall Depths
3.5.3 Hyetographs..
3.6 CUHP Modelling ............
3.6.1 Delineation of Subwatersheds
3.6.2 Imperviousness.....
3.6.3 Slope............
3.6.4 Time of Concentration

DENlOOlS182.WPS

3.0

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