1. Bentley Systems, Incorporated
3/31/2017
StormCAD Basics
Mal Sharkey
© 2002 Bentley Systems, Incorporated

2. Bentley Systems, Incorporated
3/31/2017
Be Conf. 2007
Our users design, build, and operate the world’s infrastructure – improving quality of life for everyone.
We provide software to help them do it better and faster.
© 2002 Bentley Systems, Incorporated

3. Part 1
Intro to StormCAD

4. What is a Storm Sewer System?
A storm sewer system is composed of surface components (e.g., gutters and inlets) and subsurface components (e.g., pipes, manholes, inlet boxes)

5. Storm Sewer Design
Storm sewer design and analysis consists of 2 basic parts:
Surface flow calculations
Subsurface flow calculations
Surface flow calcs evaluate the capacity of gutters (i.e., gutter spread and depth) and inlets (for inlets on grade, part of the flow, called “bypass flow,” will not be picked up and will continue down to the next inlet).
Subsurface flow calcs evaluate the capacity of the subsurface pipes to prevent flooding. Storm sewer pipes should always point downhill, and the systems are branched (i.e., typically, there should not be loops).

6. Storm Sewer Design Subsurface (pipe) layout
Surface (gutter) connectivity
Plan View
Profile View

7. Gutters Flow typically travels to storm sewer inlets though gutters
The engineer is interested in the width and depth of the gutter flow, and has to make sure that neither is excessive.
Gutter flow is analyzed using a form of Manning’s equation

8. Inlets
Three common inlet types are grate inlets, curb inlets, and combination inlets.
Inlets may be located on a continuous grade or in a sag location
Inlets on grade do not intercept 100% of the flow that comes to them—some of the flow bypasses and goes to the next inlet downgrade
HEC-22 calculation methods are used to determine gutter spread and depth and inlet capacity

9. Storm Sewer Profile

10. Bentley Systems, Incorporated
3/31/2017
StormCAD
Storm sewer design & analysis with inlet modeling
© 2002 Bentley Systems, Incorporated

11. Bentley Systems, Incorporated
3/31/2017
StormCAD
Applies to:
Commercial site design
Land development
Roadway drainage design
Planning, mapping, and inventories for larger areas (e.g., municipality)
© 2002 Bentley Systems, Incorporated

12. Bentley Systems, Incorporated
3/31/2017
StormCAD
Capabilities
Uses rational method hydrology
Performs gradually varied flow profile analysis
Incorporates HEC-22 methods for inlet and gutter capacity calcs, including gutter spread and bypass flow calcs
Performs automated pipe & inlet design
Includes GIS and database connections
Generates profile plots and tabular reports
Includes MicroStation & AutoCAD integration options
Includes Scenario Management
© 2002 Bentley Systems, Incorporated

13. Bentley Systems, Incorporated
3/31/2017
User Interface
Zoom Tools
Tabular Reports
Graphical Tools
Compute Button
Scenario
Element
Symbology
Drawing Area
Layout Tools
Background
Layers
© 2002 Bentley Systems, Incorporated

14. Bentley Systems, Incorporated
3/31/2017
Basic Data Entry
Layout Toolbar
Property Grid
Pipe Tool
Right-click menu to change element type
FlexTables
Sort
Filter
Global Edit
Customize
© 2002 Bentley Systems, Incorporated

15. ModelBuilder: Using External Data
Bentley Systems, Incorporated
3/31/2017
ModelBuilder: Using External Data
Convert CAD lines, polylines, and blocks
Connect to any database & keep it in sync with your model
Connect to shapefiles
© 2002 Bentley Systems, Incorporated

16. Part 2
Getting familiar with StormCAD

17. A little more theory… Open Channel Flow
Gutter
Open channel flow is flow that has a free water surface open to the atmosphere.
It occurs in natural rivers and streams, manmade ditches and channels, gutters, and gravity-flow pipes.

18. Conservation of Energy
In open channel flow, the pressure head term (p/γ) is replaced by the vertical flow depth y
The energy equation between sections 1 and 2 for the channel shown is written as:

19. Open Channel Flow Definitions
Normal Flow
If a channel shape remains constant for a long enough distance, the flow will reach a constant “normal depth.”
Varied Flow
Flow depth typically varies along the length of a channel due to factors like changing channel shape or flow depths other than normal depth on the upstream or downstream end.
Varied flow can change gradually along a channel (“gradually varied flow” or GVF) or rapidly (in the case of a hydraulic jump).
Supercritical vs. Subcritical Flow
These are the 2 basic flow types possible for flow in an open channel.
Supercritical flow is shallow, high-velocity flow
Subcritical flow is deeper, slower-velocity flow
Flow can transition from subcritical to supercritical flow, or vice versa
Between supercritical flow and subcritical flow is the “critical depth.” This value can be determined for any channel and used to classify the flow type. Sometimes, it is also used as a starting point (boundary condition) in GVF calculations

20. Open Channel Flow Types
Normal Flow
Transition from Subcritical to Supercritical flow
Transition from Supercritical to Subcritical Flow (Hydraulic Jump)

21. Bentley Systems, Incorporated
3/31/2017
Graphic Output
Annotation
Color Coding
Profiles
© 2002 Bentley Systems, Incorporated

22. Data Management
Queries
Network Navigator
Selection Sets

23. Part 3
Analysis in StormCAD

24. Rational Method Q = c × i × A
To compute a peak flow rate from a watershed, a method such as the Rational Method can be used:
Q = c × i × A
Q is the peak discharge from the drainage area
c is the “runoff coefficient” (the fraction of rainfall that is converted to runoff)
i is the intensity of the rainfall for a design storm event having a duration equal to the drainage area “time of concentration”. This can be obtained using intensity-duration-frequency curves for the locale (see below).
A is the area

25. Bentley Systems, Incorporated
3/31/2017
Inlet Calculations
Perform inlet capture & bypass calcs using HEC-22 methods
Store inlet properties in an engineering library
Set up gutter networks
© 2002 Bentley Systems, Incorporated

26. Bentley Systems, Incorporated
3/31/2017
Multiple Scenarios
Create alternative input data sets with Alternative Manager
Model a variety of situations using Scenario Manager
© 2002 Bentley Systems, Incorporated

27. Active Topology
Before site is developed (proposed elements are inactive)
After site is developed

28. Bentley Systems, Incorporated
3/31/2017
Viewing Output
FlexTables
Reports
Property
Grid
© 2002 Bentley Systems, Incorporated

29. StormCAD: Automated Design
Bentley Systems, Incorporated
3/31/2017
StormCAD: Automated Design
Specify global design constraints for:
Pipes (min. and max. velocity, cover, and slope; part-full flow; allowing multiple sections; and max. section size)
Nodes (matching pipe crowns or inverts at structures; offsetting pipes at structures; and allowing drop structures
Inlets (max. spread and depth for inlets in sag; min. efficiency of inlets on grade)
Design all or part of the system
Override design constraints locally
© 2002 Bentley Systems, Incorporated

30. StormCAD: Cost Manager
Bentley Systems, Incorporated
3/31/2017
StormCAD: Cost Manager
Enter cost analysis data through Cost Manager
Set up unit cost functions for materials
Adjust the cost of the overall project
Use Cost Alternatives to assign costs to project elements
© 2002 Bentley Systems, Incorporated

31. StormCAD: GIS Connections
Bentley Systems, Incorporated
3/31/2017
StormCAD: GIS Connections
Build a model or keep it synchronized with GIS data using the Shapefile Link Wizard
Modify the network in StormCAD or directly in shapefiles
© 2002 Bentley Systems, Incorporated

32. StormCAD: Database Connections
Bentley Systems, Incorporated
3/31/2017
StormCAD: Database Connections
Connect to any database to build or synchronize the model
© 2002 Bentley Systems, Incorporated

33. StormCAD: LDDT Connection
Bentley Systems, Incorporated
3/31/2017
StormCAD: LDDT Connection
Import and export pipe run data from/to Pipeworks in Autodesk Land Development Desktop Civil Design
© 2002 Bentley Systems, Incorporated

34. MicroStation & AutoCAD Integration
Bentley Systems, Incorporated
3/31/2017
MicroStation & AutoCAD Integration
StormCAD can run inside MicroStation or AutoCAD
© 2002 Bentley Systems, Incorporated

35. Bentley Systems, Incorporated
3/31/2017
StormCAD Basics
Mal Sharkey
© 2002 Bentley Systems, Incorporated