FLOOD01452

• County: Larimer
• Community: Fort Collins
• Stream Name: Fossil Creek Drainageway Basin
• Title: Master Drainageway Planning Study
• Date: 8/1/1982
• Prepared For: Larimer County
• Prepared By: Simons Li & Associates Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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LIST OF FIGURES
LIST OF TABLES
LIST OF PLATES
EXECUTIVE SUMMARY

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TABLE OF CONTENTS

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,VI.

VII.

VIII.

IV.

TABLE OF CONTENTS (continued)

FLOOD PLAIN INFORMATION

V.

4.1
4.2

Flooded Areas .
Interpretation and Use of

Report

SEDIMENTATION AND EROSION ANALYSIS

5.3

5.4

5.1
5.2

Aerial Photographs
Sediment Yield .

5.2.1
5.2.2
5.2.3
5.2.4
5.2.5
5.2.6
5.2.7
5.2.8
5.2.9

Geology
Soils
Climate
Runoff
Topography
Ground Cover
Land Use
Upland Erosion
Channel Erosion

and Sediment Transport

Stream Bank Stability .

Dominant Processes
Underlying Cause
Stream Bank Inventory

Equilibrium Slope Analysis

Method for Equilibrium Slope Analysis
Results for Equilibrium Slope Analysis

ROADWAY AND RAILROAD EMBANKMENTS

8.1
8.2

5.3.1
5.3.2
5.3.3

5.4.1
5.4.2

Overtopping .
Pipinq and Liquefaction
Slope Instabilities

FLOOD DAMAGES

ALTERNATIVE IMPROVEMENT PLANS

Improvement Alternatives
Conceptual Desiqns .

8.2.1
8.2.2
8.2.3
8.2.4

Alternative 1
Alternative 2
Alternative 3
Alternative 4

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1. INTRODUCTION
1.1 Obiectives 1
1.2 Purpose and Scope 1
1.3 Authorization . 1
1.4 Acknowledgments . 1
1.5 Mappinq and Survevinq 2
1.6 Report Acquisition 2
1.7 Related Studies . . 2
II. BASIN CHARACTERISTICS
2.1 Basin Description 3
2.2 Study Area 3
2.2.1 Fossil Creek, Reach 1 5
2.2.2 Fossil Creek, Reach 2 5
2.2.3 Fossil Creek, Reach 3 5
2.2.4 Fossil Creek, Reach 4 5
2.2.5 Fossil Creek, Reach 5 5
2.2.6 Stanton Creek, Reach 6 5
2.2.7 Lang Gulch, Reach 7 5
2.2.8 Smith Creek, Reach 8 6
2.2.9 Burns Tributary, Reach 9 . 6
2.3 Irriqation Ditches, Reservoirs, Roads and Railroads . 6
2.4 Soils 6
2.5 Wat~r Quality 6
2.6 Flood History 8
III. HYDROLOGIC AND HYDRAULIC SUMMARY
3.1 Hydrologic Analysis . 8
3.2 Rainfall Data . 8
3.3 Drainaqe Basin Parameters 8
3.4 Results 13
3.5 Hydraulic Analysis 27

6.1
6.2
6.3

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