TableOfContents TableOfContents TableOfContents TableOfContentsTableOfContentsTableOfContentsTableOfContentsTableOfContents

8/18/2019 TableOfContents TableOfContents TableOfContents TableOfContentsTableOfContentsTableOfContentsTableOfConte…

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AASHTO Drainage Manual

Volume 1—Policy

2014

American Association of State Highway

and Transportation Officials

444 North Capitol St., NW, Suite 249

Washington, DC 20001

www.transportation.org

© 2014 by the American Association of State Highway and Transportation Officials.All rights reserved.



viii

AASHTO DRAINAGE MANUAL

VOLUME 1—TABLE OF CONTENTS

Chapter 1 Introduction

Chapter 2 Legal Aspects

Chapter 3 Data Collection

Chapter 4 Documentation

Chapter 5 Software [Reserved]

Chapter 6 Planning and Location

Chapter 7 Surface Water Environment

Chapter 8 Wetland Creation and Restoration

Chapter 9 Hydrology

Chapter 10 Channels

Chapter 11 Culverts

Chapter 12 Energy Dissipators

Chapter 13 Storm Drainage Systems

Chapter 14 Storage Facilities

Chapter 15 Pump Stations

Chapter 16 Stream Stability

Chapter 17 Bridges

Chapter 18 Channel and Stream Bank Stabilization

Chapter 19 Coastal Zone

Chapter 20 Erosion and Sediment Control

Chapter 21 Construction

Chapter 22 Maintenance




x

hydrologic and hydraulic design procedures that are frequently used by highway

hydraulics engineers.

Volume One chapters can generally be grouped into the five parts listed below:

•

Part 1, General (Chapters 1–4). The introduction and chapters on legal aspects, datacollection, and documentation provide recommended policies that apply to all

drainage topics.

• Part 2, Planning and Environment (Chapters 6–8). Chapters on planning and location,

surface water environment, and wetlands provide guidelines for policies and practices

that are normally accomplished with the interaction of a hydraulics engineer before

design.

• Part 3, Highway Hydraulic Design (Chapters 9–15). Chapters pertaining to

hydrology, channels, culverts, energy dissipators, storm drainage systems, storage

facilities, and pump stations provide design policies for facilities typically designed

by highway hydraulics engineers.

• Part 4, Bridge Hydraulic Design and Floodplains (Chapters 16–19). Chapters on

stream stability, bridges, channel and stream bank stabilization, and coastal zone

provide design policies for facilities typically designed by bridge hydraulics

engineers.

• Part 5, Construction and Maintenance (Chapters 20–22). Chapters about erosion and

sediment control, construction, and maintenance provide guidelines for hydraulics

engineers to provide assistance in these areas.

Volume One chapters provide the following:

• guideline policy, criteria, and standard practices;

• reference to procedures in Volume Two; and

• overview of the subject.

Volume Two chapters can generally be grouped in the five parts listed below:

• Part 1, General (Chapters 1–5). Introduction, permits and certifications, data

collection, documentation, and software chapters provide recommended guidelines

and procedures that apply to all topics discussed in this Manual.

• Part 2, Planning and Environment (Chapters 6–8). Planning and location, surface

water environment and wetlands provide guidelines for procedures that are normally

accomplished before design with the interaction of a hydraulics engineer.

• Part 3, Highway Hydraulic Design (Chapters 9–15). Hydrology, channels, culverts,

energy dissipators, storm drainage systems, storage facilities, and pump stations




xi

chapters provide design procedures for facilities typically designed by highway

hydraulic engineers.

• Part 4, Bridge Hydraulic Design and Floodplains (Chapters 16–19). Stream stability,

bridges, channel and stream bank stabilization, and coastal zone chapters provide

design procedures for facilities typically designed by bridge hydraulic engineers.

• Part 5, Construction and Maintenance (Chapters 20–22). The erosion and sediment

control chapter provides guidelines for hydraulic engineers to provide assistance in

these areas.

Volume Two chapters provide the following:

• Reference to policy, criteria, and standards in Volume One.

• Design Procedures that the TCHH determined were frequently used have either:

o step-by-step procedures and design examples that can be worked by hand;

o step-by-step procedures and design examples that can be solved with the

FHWA Hydraulic Toolbox, FHWA HY-8, and other public domain software;

or

o reference to worked examples for procedures (e.g., storm drain design,

bridge design, and coastal engineering) that are commonly solved with

software that requires substantial expertise.

• References to recommended guidelines for less common procedures.




CHAPTER 1 – TABLE OF CONTENTS

Section Page

1.1 PURPOSE ..................................................................................................................................... 1-1

1.2 SCOPE .......................................................................................................................................... 1-11.3 U.S. CUSTOMARY UNITS ......................................................................................................... 1-1

1.4 MANUAL FORMAT ................................................................................................................... 1-2

1.5 MANUAL USE ............................................................................................................................ 1-2

1.6 REFERENCES ............................................................................................................................. 1-3

1.7 CONTENT QUESTIONS ............................................................................................................. 1-3

1.8 ERRORS, ADDITIONS, AND UPDATES .................................................................................. 1-3





Section Page

2.1 INTRODUCTION ........................................................................................................................ 2-1

2.1.1

Purpose ............................................................................................................................ 2-1 2.1.2 Overview .......................................................................................................................... 2-1

2.1.3 Order of Authority ........................................................................................................... 2-1

2.1.4 Related Publications ........................................................................................................ 2-2

2.2

FEDERAL LAWS ........................................................................................................................ 2-2

2.2.1

General Laws ................................................................................................................... 2-2

2.2.2

Drainage ........................................................................................................................... 2-2

2.2.3 Significant Laws .............................................................................................................. 2-3

2.3

WATERS OF THE UNITED STATES REGULATIONS ........................................................... 2-4

2.3.1 Constitutional Power ........................................................................................................ 2-4

2.3.2 Federal Agencies .............................................................................................................. 2-4

2.3.2.1 U.S. Coast Guard (USCG) ............................................................................. 2-4

2.3.2.2

U.S. Army Corps of Engineers (USACE) ..................................................... 2-5

2.3.2.3

Federal Highway Administration (FHWA) ................................................... 2-6

2.3.2.4

U.S. Environmental Protection Agency (U.S. EPA) ..................................... 2-6

2.4 FISH AND WILDLIFE SERVICE (U.S. FWS) ........................................................................... 2-7

2.4.1 Requirements ................................................................................................................... 2-7

2.4.2

U.S. FWS Role................................................................................................................. 2-7

2.5 NATIONAL FLOOD INSURANCE PROGRAM ....................................................................... 2-7

2.5.1 Flood Insurance ................................................................................................................ 2-7

2.5.2

Flood Disaster Protection ................................................................................................. 2-8

2.5.3 Local Community ............................................................................................................ 2-8

2.5.4 NFIP Maps ....................................................................................................................... 2-8

2.5.5 Coordination with FEMA ................................................................................................ 2-9

2.5.5.1 Consistent with Floodways .......................................................................... 2-10

2.5.5.2 Revisions of Floodway ................................................................................ 2-10

2.5.5.3 Data for Revisions ....................................................................................... 2-11

2.5.5.4

Allowable Floodway Encroachment............................................................ 2-11

2.5.5.5

Highway Encroachment on a Floodplain with a Detailed Study (FIRM) ... 2-12

2.5.5.6

Highway Encroachment on a Floodplain Indicated on an FHBM ............... 2-12

2.5.5.7 Highway Encroachment on Unidentified Floodplains................................. 2-12

2.5.6 Levee Systems ............................................................................................................... 2-12

2.5.7 Revisions to NFIP Maps ................................................................................................ 2-13




2-iv AASHTO Drainage Manual, Volume One “Policy ”

2.6

EXECUTIVE ORDERS ............................................................................................................. 2-13

2.6.1

Background .................................................................................................................... 2-13

2.6.2

EO 11988 ....................................................................................................................... 2-13

2.6.3 EO 11990 ....................................................................................................................... 2-14

2.7 STATE DRAINAGE LAW ........................................................................................................ 2-14

2.7.1

Common and Statutory Law .......................................................................................... 2-14

2.7.2 Classification of Waters ................................................................................................. 2-14

2.8 STATE WATER RULES ........................................................................................................... 2-15

2.8.1 Basic Concepts ............................................................................................................... 2-15

2.8.2

Surface Waters ............................................................................................................... 2-16

2.8.3

Stream Waters ................................................................................................................ 2-16

2.8.4

Floodwaters .................................................................................................................... 2-17

2.8.5 Groundwater .................................................................................................................. 2-17

2.9

STATUTORY LAW ................................................................................................................... 2-17

2.9.1 Introduction .................................................................................................................... 2-17

2.9.2 Eminent Domain ............................................................................................................ 2-18

2.9.3 Water Rights .................................................................................................................. 2-18

2.9.4 Districts .......................................................................................................................... 2-19

2.9.5

Agricultural Drainage Laws ........................................................................................... 2-19

2.9.6

Environmental Law ........................................................................................................ 2-19

2.10 LOCAL LAWS AND APPLICATIONS .................................................................................... 2-19

2.10.1 Local Laws ..................................................................................................................... 2-19

2.10.2

Municipal Liability ........................................................................................................ 2-19

2.10.3

Acts of Others ................................................................................................................ 2-20

2.10.4

Acts of Developers ......................................................................................................... 2-20

2.10.5

Personal Liability ........................................................................................................... 2-21

2.10.6 Drainage Improvements ................................................................................................. 2-21

2.10.7 Financing ..................................................................................................................... 2-21

2.10.8 Special Issues ................................................................................................................. 2-21

2.11 LEGAL REMEDIES .................................................................................................................. 2-21

2.11.1 Common Actions ........................................................................................................... 2-21

2.11.2

Inverse Condemnation ................................................................................................... 2-22

2.11.3

Injunction ..................................................................................................................... 2-22

2.11.4

Tort Claims .................................................................................................................... 2-22

2.11.5 Legislative Claims ......................................................................................................... 2-22

2.12 ROLE OF THE DESIGNER ...................................................................................................... 2-22

2.12.1 Responsibility ................................................................................................................ 2-22

2.12.2 Investigating Complaints ............................................................................................... 2-23

2.12.3 Legal Opinion ................................................................................................................ 2-25




Legal Aspects 2-v

2.12.4 As a Witness .................................................................................................................. 2-25

2.12.5 Witness Conduct ............................................................................................................ 2-26

2.13 REFERENCES ........................................................................................................................... 2-26



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Section Page

3.1 INTRODUCTION ........................................................................................................................ 3-1

3.1.1 Purpose ............................................................................................................................ 3-13.1.2 Overview .......................................................................................................................... 3-1

3.1.3 Accuracy of Data ............................................................................................................. 3-1

3.2 GENERAL CONSIDERATIONS ................................................................................................ 3-2

3.2.1 Regulatory ........................................................................................................................ 3-2

3.2.2 Data Retention Policy ...................................................................................................... 3-2

3.3 REFERENCES ............................................................................................................................. 3-3





Section Page

4.1 INTRODUCTION ........................................................................................................................ 4-1

4.1.1 Overview .......................................................................................................................... 4-14.1.2 Purpose ............................................................................................................................ 4-1

4.1.3 Objectives ........................................................................................................................ 4-2

4.1.4 Phases .............................................................................................................................. 4-3

4.1.4.1 Preliminary Engineering ................................................................................ 4-3

4.1.4.2 Design ............................................................................................................ 4-3

4.1.4.3 Construction .................................................................................................. 4-3

4.1.4.4 Operation ....................................................................................................... 4-3

4.2 RECORDS AND FILES ............................................................................................................... 4-4

4.2.1 General File ...................................................................................................................... 4-44.2.2 Hydraulic Site File (Structures) ....................................................................................... 4-4

4.2.2.1 Design Computations .................................................................................... 4-5

4.2.2.2 Site-Specific Correspondence ........................................................................ 4-5

4.2.2.3 Hydraulic Site File Checklist ......................................................................... 4-5

4.2.3 Hydraulic Site File (Roadway) ........................................................................................ 4-6

4.2.3.1 General .......................................................................................................... 4-6

4.2.3.2 Rural Drainage ............................................................................................... 4-6

4.2.3.3 Storm Drainage Systems ............................................................................... 4-6

4.2.4 Permits File ...................................................................................................................... 4-6

4.2.5 Maintenance of Files ........................................................................................................ 4-64.2.6 Documentation of Flood Events (Highwater) .................................................................. 4-7





Section Page

6.1 INTRODUCTION ........................................................................................................................ 6-1

6.1.1

Purpose ............................................................................................................................ 6-1 6.1.2 Overview .......................................................................................................................... 6-1


6.2.1 Planning Highway Drainage ............................................................................................ 6-2

6.2.2

Regulations ...................................................................................................................... 6-2

6.2.3

Data Collection ................................................................................................................ 6-2

6.2.4

Planning-Level Hydrology and Hydraulics Reports ........................................................ 6-3

6.3 DOT PRACTICE .......................................................................................................................... 6-3

6.3.1

Interagency Coordination................................................................................................. 6-3

6.3.2 Legal Aspects ................................................................................................................... 6-4

6.3.3 Environmental Considerations ......................................................................................... 6-4

6.3.4 Permits ............................................................................................................................. 6-5

6.3.5

Location Considerations .................................................................................................. 6-5

6.4

REFERENCES ............................................................................................................................. 6-6





Section Page

7.1 INTRODUCTION ........................................................................................................................ 7-1

7.1.1 Purpose ............................................................................................................................ 7-1

7.1.2

General Definitions .......................................................................................................... 7-2

7.1.3

Surface Waters ................................................................................................................. 7-3

7.1.4

Sensitive Surface Waters ................................................................................................. 7-3

7.1.5 Functional Values ............................................................................................................ 7-3

7.1.6 Impact and Significance ................................................................................................... 7-4

7.1.6.1 Impact .............................................................................................................. 7-4

7.1.6.2 Significance ..................................................................................................... 7-4

7.1.7 Threshold Value ............................................................................................................... 7-5

7.1.8 Reversible Effects ............................................................................................................ 7-5

7.1.9

Practicable ........................................................................................................................ 7-5

7.1.10

Design Alternatives .......................................................................................................... 7-5

7.2 POLICY ........................................................................................................................................ 7-7

7.2.1 Introduction ...................................................................................................................... 7-7

7.2.2 Rules and Regulations ..................................................................................................... 7-7

7.2.2.1 Federal Requirements ...................................................................................... 7-7

7.2.2.2 Federal MOUs and MOAs ............................................................................... 7-8

7.2.2.3 State and Local Requirements ......................................................................... 7-8

7.2.3 Cost-Effectiveness ........................................................................................................... 7-8

7.2.4

Enhancing Functional Values .......................................................................................... 7-8

7.2.5

Environmental Evaluation Complexity ............................................................................ 7-8

7.2.6 Surface Water Assessment ............................................................................................... 7-9

7.2.7 Surface Water Analysis ................................................................................................... 7-9

7.2.8 Permit Criteria .................................................................................................................. 7-9

7.2.9 Design Mitigation .......................................................................................................... 7-10

7.2.9.1 Mitigation Alternatives .................................................................................. 7-10

7.2.9.2

Best Management Practices (BMPs) ............................................................. 7-10

7.3

FUNCTIONAL VALUE CONSIDERATIONS ......................................................................... 7-10

7.3.1 Water Quality and Quantity ........................................................................................... 7-11

7.3.2

Channels......................................................................................................................... 7-11 7.3.2.1 Classification ................................................................................................. 7-12

7.3.2.2 Ordinary Highwater (OHW) .......................................................................... 7-12

7.3.2.3 Stability.......................................................................................................... 7-12

7.3.2.4 Channel Control Facilities ............................................................................. 7-13

7.3.3 Lakes or Ponds ............................................................................................................... 7-13

7.3.4

Wetlands ........................................................................................................................ 7-14

7.3.5

Aquatic Organism Passage (AOP) ................................................................................. 7-14




7-iv AASHTO Drainage Manual, Volume One “Policy”

7.3.6 Stream Geometry and Cover .......................................................................................... 7-14

7.3.6.1

Riparian Cover ............................................................................................... 7-14

7.3.6.2

In-stream Features ......................................................................................... 7-15

7.3.6.3 Substrate ........................................................................................................ 7-15

7.3.6.4 Bank Geometry .............................................................................................. 7-15

7.3.6.5 Conveyance ................................................................................................... 7-15

7.4 REFERENCES ........................................................................................................................... 7-15





Section Page

8.1 INTRODUCTION ........................................................................................................................ 8-1


8.1.3 Wetland Definition .......................................................................................................... 8-2

8.1.4 Wetland Functions ........................................................................................................... 8-3


8.2.1 Regulatory Considerations ............................................................................................... 8-3

8.2.1.1 Federal ........................................................................................................... 8-4

8.2.1.2 State and Local .............................................................................................. 8-4

8.2.1.3 Permit Criteria ............................................................................................... 8-5

8.2.2 Design Considerations ..................................................................................................... 8-58.2.2.1 Wetland Mitigation Alternatives ................................................................... 8-5

8.2.2.2 Wetland Bank ................................................................................................ 8-5

8.2.2.3 Impacts to Wetland Hydrology ...................................................................... 8-6

8.3 PROCEDURAL OVERVIEW ...................................................................................................... 8-6

8.3.1 Wetland Project Team ..................................................................................................... 8-6

8.3.2 Wetland Project Development Process ............................................................................ 8-7

8.4 WETLAND CLASSIFICATION ................................................................................................. 8-8

8.5 REFERENCES ........................................................................................................................... 8-10





Section Page

9.1 INTRODUCTION ........................................................................................................................ 9-1



9.2.1 Factors Affecting Floods ................................................................................................. 9-2

9.2.2 Sources of Information .................................................................................................... 9-2

9.2.3 Site Data ........................................................................................................................... 9-2

9.2.4 Evaluation of Runoff Factors ........................................................................................... 9-2

9.2.5 Flood History ................................................................................................................... 9-3

9.2.6 Design Frequency ............................................................................................................ 9-3

9.2.7 Economics ........................................................................................................................ 9-39.2.8 Review Frequency ........................................................................................................... 9-4

9.3 HYDROLOGIC ANALYSIS METHODS ................................................................................... 9-4

9.3.1 General ............................................................................................................................. 9-4

9.3.2 Overview .......................................................................................................................... 9-4

9.3.3 Peak Flow Analyses ......................................................................................................... 9-5

9.3.3.1 Gauged Site Methods..................................................................................... 9-6

9.3.3.2 Ungauged Site Methods ................................................................................. 9-7

9.3.4 Hydrograph Methods ....................................................................................................... 9-8

9.3.4.1 NRCS Hydrograph Method ........................................................................... 9-89.3.4.2 Unit Hydrographs–Gauge Data and Synthetic .............................................. 9-8

9.3.5 Hydrologic Accuracy ....................................................................................................... 9-9

9.3.6 Calibration ....................................................................................................................... 9-9

9.4 REFERENCES ............................................................................................................................. 9-9





Section Page

10.1 INTRODUCTION ...................................................................................................................... 10-1

10.1.1 Purpose .......................................................................................................................... 10-110.1.2 Overview ........................................................................................................................ 10-1

10.2 DESIGN STANDARDS ............................................................................................................. 10-2

10.2.1 Stream Channels ............................................................................................................ 10-2

10.2.2 Dikes and Levees ........................................................................................................... 10-3

10.2.3 Roadside Channels ......................................................................................................... 10-3

10.3 GENERAL CHANNEL DESIGN CONSIDERATIONS ........................................................... 10-4

10.4 CHANNEL HYDRAULIC ANALYSIS .................................................................................... 10-5 10.4.1 General ........................................................................................................................... 10-5

10.4.2 Single-Section Analysis (Slope-Area Method) .............................................................. 10-6

10.4.3 Step-Backwater Method................................................................................................. 10-6

10.4.4 Special Analysis Techniques ......................................................................................... 10-6

10.4.4.1 Two-Dimensional Analysis ......................................................................... 10-7

10.4.4.2 Water and Sediment Routing ....................................................................... 10-7

10.4.4.3 Unsteady Flow Analysis .............................................................................. 10-7

10.5 REFERENCES ........................................................................................................................... 10-8





Section Page

11.1 INTRODUCTION ...................................................................................................................... 11-1

11.2 GENERAL CONSIDERATIONS .............................................................................................. 11-1

11.3 DESIGN CRITERIA .................................................................................................................. 11-2

11.3.1 Site Criteria .................................................................................................................... 11-2

11.3.1.1 Structure Type Selection ............................................................................. 11-2

11.3.1.2 Slope, Length, and Skewness ...................................................................... 11-2

11.3.1.3 Ice Buildup .................................................................................................. 11-3

11.3.1.4 Debris Control ............................................................................................. 11-3

11.3.2 Design Limitations ......................................................................................................... 11-3

11.3.2.1 Design Flood Frequency .............................................................................. 11-311.3.2.2 Review Flood Frequency ............................................................................. 11-4

11.3.2.3 Allowable Headwater .................................................................................. 11-4

11.3.2.4 Allowable Headwater for Temporary On-Site Traffic Diversions .............. 11-4

11.3.2.5 Tailwater Relationship (Channel) ................................................................ 11-4

11.3.2.6 Tailwater Relationship (Confluence or Large-Water Body) ....................... 11-5

11.3.2.7 Maximum Outlet Velocity ........................................................................... 11-5

11.3.2.8 Minimum Culvert Velocity ......................................................................... 11-6

11.3.2.9 Storage (Temporary or Permanent) ............................................................. 11-6

11.4 DESIGN FEATURES ................................................................................................................. 11-611.4.1 Culvert Shape and Material Selection ............................................................................ 11-6

11.4.2 Culvert Size .................................................................................................................... 11-7

11.4.3 Broken-Back Culverts .................................................................................................... 11-7

11.4.4 Land-Use Culvert ........................................................................................................... 11-7

11.4.5 Multiple Barrels ............................................................................................................. 11-8

11.4.6 Culvert Slopes ................................................................................................................ 11-8

11.4.7 Pipe Length Measurement for Culverts ......................................................................... 11-9

11.4.8 Skewed Installations ...................................................................................................... 11-9

11.4.9 End Treatment (Inlet or Outlet) ..................................................................................... 11-9

11.4.10 Safety Considerations .................................................................................................. 11-10

11.4.11 Median and Entrance Placement .................................................................................. 11-10

11.4.12 Weep Holes .................................................................................................................. 11-10

11.4.13 Performance Curves ..................................................................................................... 11-10

11.5 RELATED DESIGNS .............................................................................................................. 11-11

11.5.1 Erosion and Sediment Control ..................................................................................... 11-11

11.5.2 Environmental Considerations and Fishery Protection ................................................ 11-11

11.5.3 Irrigation Facilities ....................................................................................................... 11-11





11.5.4 Outlet Protection .......................................................................................................... 11-12

11.5.5 Relief Opening ............................................................................................................. 11-12

11.6 REFERENCES ......................................................................................................................... 11-12





Section Page

12.1 INTRODUCTION ...................................................................................................................... 12-1

12.1.1 Overview ........................................................................................................................ 12-112.1.2 Definition ....................................................................................................................... 12-1

12.1.3 HEC-14 .......................................................................................................................... 12-1

12.2 TYPE SELECTION .................................................................................................................... 12-1

12.2.1 General ........................................................................................................................... 12-1

12.2.2 DOT Practice (Example) ............................................................................................... 12-3

12.2.3 Guidelines ...................................................................................................................... 12-3

12.3 DESIGN CONSIDERATIONS .................................................................................................. 12-4

12.3.1 Ice Buildup ..................................................................................................................... 12-412.3.2 Debris Control ................................................................................................................ 12-4

12.3.3 Flood Frequency ............................................................................................................ 12-4

12.3.4 Culvert Exit Velocity ..................................................................................................... 12-4

12.3.5 Tailwater Relationship ................................................................................................... 12-4

12.3.6 Cost ................................................................................................................................ 12-5

12.3.7 Weep Holes .................................................................................................................... 12-5

12.4 REFERENCES ........................................................................................................................... 12-5





Section Page

13.1 OVERVIEW ............................................................................................................................... 13-1

13.1.1

Introduction .................................................................................................................... 13-1 13.1.2 Inadequate Drainage ...................................................................................................... 13-2

13.1.3 General Design Guidelines ............................................................................................ 13-2

13.1.4 Detention Storage .......................................................................................................... 13-2

13.2

GENERAL CONSIDERATIONS .............................................................................................. 13-3

13.2.1

Introduction .................................................................................................................... 13-3

13.2.2

Hydrology ...................................................................................................................... 13-3

13.2.3 Bridge Decks .................................................................................................................. 13-3

13.2.4 Inlets .............................................................................................................................. 13-3

13.2.5

Storm Drains .................................................................................................................. 13-4

13.2.6 Roadside Channels and Ditches ..................................................................................... 13-4

13.2.7 Flood Hazard .................................................................................................................. 13-5

13.2.8 Property Development Drainage Policy ........................................................................ 13-5

13.2.9

Hydroplaning ................................................................................................................. 13-5

13.2.10

Manholes ........................................................................................................................ 13-6

13.2.10.1

Location ....................................................................................................... 13-6

13.2.10.2 Spacing ........................................................................................................ 13-6

13.3 DESIGN FREQUENCY AND SPREAD ................................................................................... 13-7

13.3.1

Selection Considerations ................................................................................................ 13-7

13.3.2

Design Frequency .......................................................................................................... 13-7

13.3.3 Review Flood Frequency ............................................................................................... 13-8

13.3.4

Design Spread ................................................................................................................ 13-8

13.4 ROADWAY GEOMETRICS ..................................................................................................... 13-8

13.4.1 Introduction .................................................................................................................... 13-8

13.4.2 Roadway Cross Section ................................................................................................. 13-9

13.4.2.1 Width ........................................................................................................... 13-9

13.4.2.2 Cross Slope .................................................................................................. 13-9

13.4.3 Vertical Alignment ...................................................................................................... 13-10

13.4.3.1

Longitudinal Slope .................................................................................... 13-10

13.4.3.2

Sag Vertical Curves ................................................................................... 13-10

13.4.3.3

Crest Vertical Curves ................................................................................. 13-10

13.4.4 Pavement Texture ........................................................................................................ 13-10

13.4.5 Curb and Gutter ........................................................................................................... 13-11

13.4.6 Medians ........................................................................................................................ 13-11

13.5 REFERENCES ......................................................................................................................... 13-12





Section Page

14.1 INTRODUCTION ...................................................................................................................... 14-1

14.1.1 Overview ........................................................................................................................ 14-114.1.1.1 Quality ......................................................................................................... 14-1

14.1.1.2 Quantity ....................................................................................................... 14-1

14.1.2 Location Considerations ................................................................................................ 14-2

14.1.3 Detention and Retention ................................................................................................ 14-2

14.1.4 Design Practice .............................................................................................................. 14-2

14.2 POLICY ...................................................................................................................................... 14-3

14.3 DESIGN CRITERIA .................................................................................................................. 14-3

14.3.1 General Criteria .............................................................................................................. 14-314.3.2 Release Rate ................................................................................................................... 14-4

14.3.3 Storage Volume ............................................................................................................. 14-4

14.3.4 Grading and Depth Requirements .................................................................................. 14-4

14.3.4.1 General ........................................................................................................ 14-4

14.3.4.2 Detention ..................................................................................................... 14-5

14.3.4.3 Retention ...................................................................................................... 14-5

14.3.5 Outlet Works .................................................................................................................. 14-5

14.3.6 Location ......................................................................................................................... 14-5

14.4 NATIONAL DAM SAFETY PROGRAM ................................................................................. 14-6

14.5 CONSTRUCTION AND MAINTENANCE CONSIDERATIONS .......................................... 14-6

14.5.1 General ........................................................................................................................... 14-6

14.5.2 Sediment Basins ............................................................................................................. 14-7

14.5.3 Design Considerations for Pedestrians .......................................................................... 14-7

14.6 REFERENCES ........................................................................................................................... 14-7





Section Page

15.1 INTRODUCTION ...................................................................................................................... 15-1

15.1.1 Purpose .......................................................................................................................... 15-115.1.2 Overview ........................................................................................................................ 15-1

15.1.3 Policy ............................................................................................................................. 15-2

15.1.4 Design Considerations ................................................................................................... 15-2

15.2 DESIGN CONSIDERATIONS .................................................................................................. 15-3

15.2.1 Location ......................................................................................................................... 15-3

15.2.2 Hydrology ...................................................................................................................... 15-3

15.2.3 Collection Systems ........................................................................................................ 15-4

15.2.4 Station Types ................................................................................................................. 15-5

15.2.4.1 Wet-Pit Stations ........................................................................................... 15-515.2.4.2 Dry-Pit Stations ........................................................................................... 15-6

15.2.5 Pump Types ............................................................................................................. ...... 15-7

15.2.6 Submergence .................................................................................................................. 15-8

15.2.7 Water-Level Sensors ...................................................................................................... 15-9

15.2.8 Power ............................................................................................................................. 15-9

15.2.9 Discharge System ........................................................................................................ 15-10

15.2.10 Flap Gates and Valving ................................................................................................ 15-10

15.2.10.1 Flap Gates .................................................................................................. 15-10

15.2.10.2 Check Valves ............................................................................................. 15-10

15.2.10.3 Gate Valves ............................................................................................... 15-1115.2.10.4 Air/Vacuum Valves ................................................................................... 15-11

15.2.11 Trash Racks and Grit Chambers .................................................................................. 15-11

15.2.12 Ventilation ................................................................................................................... 15-11

15.2.13 Roof Hatches and Monorails ....................................................................................... 15-12

15.2.14 Equipment Certification and Testing ........................................................................... 15-12

15.2.15 Monitoring ................................................................................................................... 15-12

15.2.16 Hazardous Spills .......................................................................................................... 15-12

15.3 CONSTRUCTION AND OPERATION CONSIDERATIONS ............................................... 15-13

15.3.1 Construction ................................................................................................................. 15-13

15.3.2 Maintenance ................................................................................................................. 15-13

15.3.3 Retrofitting Stations ..................................................................................................... 15-13

15.3.4 Safety ........................................................................................................................... 15-14

15.4 DESIGN CRITERIA ................................................................................................................ 15-14

15.4.1 Objective ...................................................................................................................... 15-14

15.4.2 Station Type and Depth ............................................................................................... 15-14

15.4.3 Power ........................................................................................................................... 15-14

15.4.4 Total Dynamic Head and System Curve ...................................................................... 15-15





15.4.5 Main Pumps ................................................................................................................. 15-16

15.4.5.1 Number and Capacity ................................................................................ 15-16

15.4.5.2 Final Selection ........................................................................................... 15-17

15.4.6 Standby or Spare Pumps .............................................................................................. 15-19

15.4.7 Sump Pumps ................................................................................................................ 15-19

15.4.8 Storage ......................................................................................................................... 15-19

15.4.9 Wet Well Design .......................................................................................................... 15-20

15.4.9.1 Cycling Sequence and Volumes ................................................................ 15-21

15.4.9.2 Lowest Pump “Off” Elevation ................................................................... 15-24

15.4.9.3 Pump “On” Elevation ................................................................................ 15-25

15.4.9.4 Allowable Highwater Elevation ................................................................ 15-25

15.4.9.5 Clearances .................................................................................................. 15-25

15.4.9.6 Intake System Design ................................................................................ 15-25

15.4.10 Stormwater Pump Station Storage ............................................................................... 15-25

15.5 REFERENCES ......................................................................................................................... 15-26





Section Page

16.1 INTRODUCTION ...................................................................................................................... 16-1

16.1.1

Policy ............................................................................................................................. 16-1 16.1.2 Location of Stream Crossing ......................................................................................... 16-1

16.2 FLUVIAL GEOMORPHOLOGY .............................................................................................. 16-1

16.2.1

Alluvial Streams ............................................................................................................ 16-2

16.2.2

Stream Types ................................................................................................................. 16-5

16.2.2.1

Straight Streams ............................................................................................. 16-5

16.2.2.2

Braided Streams ............................................................................................. 16-6

16.2.2.3 Meandering Streams ...................................................................................... 16-7

16.2.3 Graded or Poised Streams .............................................................................................. 16-8

16.2.4

Stream System Response ............................................................................................... 16-9

16.3 STREAM STABILITY ASSESSMENT .................................................................................. 16-10

16.3.1 Objective ...................................................................................................................... 16-10

16.3.2

Stream Reconnaissance ................................................................................................ 16-10

16.3.3

Levels of Assessment ................................................................................................... 16-10

16.3.3.1

Level 1: Qualitative Geomorphic Analyses ................................................. 16-11

16.3.3.2 Level 2: Basic Engineering Analyses .......................................................... 16-11

16.3.3.3 Level 3: Mathematical and Physical Model Studies .................................... 16-11

16.3.4 Factors that Affect Stream Stability ............................................................................. 16-11

16.3.4.1

Geomorphic Factors .................................................................................... 16-12

16.3.4.2

Hydraulic Factors ........................................................................................ 16-14

16.3.5 Stream Response to Change......................................................................................... 16-16

16.3.6 Lateral Migration ......................................................................................................... 16-18

16.4 COUNTERMEASURES FOR STREAM INSTABILITY ....................................................... 16-18

16.4.1 Meander Migration ...................................................................................................... 16-19

16.4.2 Channel Braiding ......................................................................................................... 16-19

16.4.3 Degradation .................................................................................................................. 16-19

16.4.4 Aggradation ................................................................................................................. 16-20

16.5

REFERENCES ......................................................................................................................... 16-20





Section Page

17.1 INTRODUCTION ...................................................................................................................... 17-1

17.1.1 Purpose of Chapter ......................................................................................................... 17-117.1.2 Bridge Definition ........................................................................................................... 17-1

17.1.3 Hydraulic Design (Culvert or Bridge) ........................................................................... 17-2

17.1.4 Design Goals .................................................................................................................. 17-2

17.1.5 Data Collection .............................................................................................................. 17-2

17.2 BRIDGE LOCATION ................................................................................................................ 17-3

17.2.1 General Considerations .................................................................................................. 17-3

17.2.2 Location Considerations ................................................................................................ 17-3

17.2.3 Auxiliary/Relief Openings ............................................................................................. 17-3

17.3 HYDRAULIC PERFORMANCE CRITERIA ........................................................................... 17-4


17.3.2 Flood Frequencies .......................................................................................................... 17-5

17.3.2.1 Design Flood (Interstate and State Highways) ............................................ 17-5

17.3.2.2 Design Flood (Non-State Highways)........................................................... 17-6

17.3.2.3 NFIP-Mapped Floodplains .......................................................................... 17-6

17.3.2.4 Review Flood ............................................................................................... 17-6

17.3.2.5 Risk Assessment/Analysis ........................................................................... 17-7

17.3.3 Clearance ....................................................................................................................... 17-8

17.3.4 Bridge Deck and Roadway Freeboard ........................................................................... 17-817.3.5 Backwater ...................................................................................................................... 17-8

17.4 HYDRAULIC ANALYSIS REQUIREMENTS ........................................................................ 17-9


17.4.2 Analysis Documentation .............................................................................................. 17-10

17.4.3 Waterway Enlargement ................................................................................................ 17-10

17.5 BRIDGE SCOUR ..................................................................................................................... 17-11

17.5.1 Introduction .................................................................................................................. 17-11

17.5.2 General Considerations ................................................................................................ 17-12

17.5.3 Flood Magnitudes ........................................................................................................ 17-12

17.5.4 Scour Types ................................................................................................................. 17-13

17.5.4.1 Long-Term Profile Changes ...................................................................... 17-13

17.5.4.2 Contraction ................................................................................................ 17-13

17.5.4.3 Local Scour ................................................................................................ 17-13

17.5.5 Natural Armoring ......................................................................................................... 17-14

17.5.6 Scour-Resistant Materials ............................................................................................ 17-14

17.5.7 Cumulative Scour Analysis.......................................................................................... 17-14

17.5.8 Pressure Flow Scour .................................................................................................... 17-15





17.5.9 Scour Countermeasures ............................................................................................... 17-15

17.5.10 Dikes and Levees ......................................................................................................... 17-17

17.6 DECK DRAINAGE .................................................................................................................. 17-18

17.6.1 Importance of Bridge Deck Drainage .......................................................................... 17-18

17.6.2 Design Responsibilities ................................................................................................ 17-19

17.6.3 Design Considerations (Open Drainage) ..................................................................... 17-19

17.6.3.1 Type of Drainage System .......................................................................... 17-19

17.6.3.2 Deck Slope ................................................................................................. 17-19

17.6.3.3 Sag Vertical Curves ................................................................................... 17-19

17.6.3.4 Downspouts ............................................................................................... 17-19

17.6.3.5 Location of Inlets ....................................................................................... 17-20

17.6.3.6 Structural Considerations .......................................................................... 17-21

17.6.3.7 Maintenance Considerations ...................................................................... 17-21

17.6.3.8 Bridge End Drainage ................................................................................. 17-21

17.7 OTHER CONSIDERATIONS .................................................................................................. 17-21

17.7.1 General ......................................................................................................................... 17-21

17.7.2 Environmental Considerations ..................................................................................... 17-22

17.7.3 Coordination, Permits, and Approvals ......................................................................... 17-22

17.7.4 Construction and Maintenance .................................................................................... 17-23

17.7.5 Tidal Waterways .......................................................................................................... 17-23

17.8 REFERENCES ......................................................................................................................... 17-23





Section Page

18.1 INTRODUCTION ........................................................................................................................... 1

18.1.1 Overview ............................................................................................................................. 118.1.2 Policy .................................................................................................................................. 1

18.1.3 HEC-23 ............................................................................................................................... 2

18.1.4 Stream Stability ................................................................................................................... 2

18.1.5 Bank and Revetment Failure Modes ................................................................................... 3

18.1.6 Hydraulic Analysis ............................................................................................................. 4

18.2 CHANNEL STABILIZATION METHODS ................................................................................... 4

18.2.1 Spurs or Spur Dikes ............................................................................................................ 6

18.2.2 Bendway Weirs ................................................................................................................... 7

18.2.3 Grade Control ..................................................................................................................... 818.2.4 Guide Banks ........................................................................................................................ 9

18.2.5 Retardance Structures ....................................................................................................... 10

18.2.6 Bulkheads.......................................................................................................................... 11

18.3 REVETMENT METHODS ........................................................................................................... 13

18.3.1 Rock and Rubble Riprap ................................................................................................... 14

18.3.2 Gabions ............................................................................................................................. 14

18.3.3 Wire-Enclosed Rock ......................................................................................................... 14

18.3.4 Precast Concrete Block ..................................................................................................... 15

18.3.5 Fully and Partially Grouted Rock ..................................................................................... 1518.3.6 Concrete Slope Protection................................................................................................. 16

18.3.7 Vegetative Plantings and Hybrid Revetments (Biotechnical Engineering) ...................... 16

18.3.8 Filter Requirements ........................................................................................................... 17

18.4 REFERENCES .............................................................................................................................. 17





Section Page

19.1 INTRODUCTION ...................................................................................................................... 19-1

19.1.1 Purpose .......................................................................................................................... 19-1

19.1.2 Introduction .................................................................................................................... 19-119.1.3 Symbols and Definitions ................................................................................................ 19-1

19.2 GENERAL CONSIDERATIONS .............................................................................................. 19-2

19.2.1 Coastal Engineers .......................................................................................................... 19-2

19.2.1.1 Qualifying a Coastal Engineer .......

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