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StormCAD BasicsMal Sharkey
Be Conf. 2007Our 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.
Part 1
• Intro to StormCAD
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)
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).
Storm Sewer Design
P a rk in g L o t a n d R o a d w a yS to r m S e w e r C o ll e c t io n S y s t e mSA M P L E 4
S a m p le 4
J a n 2 0 0 3Ha e s ta d M e th o ds In c .
S h e e t 1 / 1
P-P
L2
P-O2
I- 4R
J- 2
I- PL2I- PL1
J- 5
I- 3L
I- 4L
I- PL3
I- 3R
Outlet
J- 1
I- 2R
I- 1R
I- 1L
J- 3
J- 4
E l e va t io n (f t )
S ta t i o n ( f t )
Profile : I-1 l to O utlet
S c e n a r i o : 1 0 0 - y e a r S t o rm
0 + 0 0 1 + 0 0 2 + 0 0 3 + 0 0 4 + 0 0 5 + 0 05 0 5 .0 0
5 1 0 .0 0
5 1 5 .0 0
5 2 0 .0 0S u m p : 5 1 3 .5 3 f tR im : 5 1 8 .2 0 f tL a b e l : I -1 L
S u m p : 5 1 3 .5 1 f tR im : 5 1 8 .4 0 f tL a b e l : J- 1
S u m p : 5 1 1 .1 5 f tR im : 5 1 6 .9 0 f tL a b e l : J- 2
S u m p : 5 1 0 .8 0 f tR im : 5 1 6 .8 0 f tL a b e l : I -2 R
S u m p : 5 1 0 .7 2 f tR im : 5 1 8 .2 0 f tL a b e l : J- 5
S u m p : 5 0 8 .6 0 f tR im : 5 1 0 .6 0 f tL a b e l : O u t le t
S : 0 .0 0 1 5 0 0 f t / f tS i ze : 8 in c hL : 1 3 .0 0 f tD n . In v e rt : 5 1 3 .5 1 f tU p . In v e rt : 5 1 3 .5 3 f tL a b e l : P - 1 L
S : 0 .0 2 2 5 1 3 f t / f tS i ze : 8 in c hL : 1 0 5 .0 0 f tD n . In v e rt : 5 1 1 .1 5 f tU p . In v e rt : 5 1 3 .5 1 f tL a b e l : P - C 1
S : 0 .0 2 6 9 2 3 f t / f tS i ze : 1 5 in chL : 1 3 .0 0 f tD n . In v e rt : 5 1 0 .8 0 f tU p . In v e rt : 5 1 1 .1 5 f tL a b e l : P - 2 R
S : 0 .0 0 1 5 0 0 f t / f tS i ze : 2 4 in chL : 5 5 .5 0 f tD n . In v e rt : 5 1 0 .7 2 f tU p . In v e rt : 5 1 0 .8 0 f tL a b e l : P - O 1
S : 0 .0 0 8 9 5 0 f t / f tS i ze : 2 4 in chL : 2 3 6 .5 0 f tD n . In v e rt : 5 0 8 .6 0 f tU p . In v e rt : 5 1 0 .7 2 f tL a b e l : P - O 2
Subsurface (pipe) layout
Profile View
Plan View Surface (gutter) connectivity
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
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
Storm Sewer Profile
StormCADStorm sewer design & analysis with inlet modeling
StormCAD
Applies to:− Commercial site design− Land development− Roadway drainage design− Planning, mapping, and inventories for
larger areas (e.g., municipality)
StormCADCapabilities
− 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
User Interface
Drawing Area
Scenario
Layout Tools
Graphical Tools
Zoom ToolsCompute Button
Tabular Reports
Element Symbology
BackgroundLayers
Basic Data EntryLayout Toolbar
Pipe Tool
Right-click menu to change element type
Property Grid
FlexTables
• Sort• Filter• Global Edit• Customize
ModelBuilder: Using External Data Convert CAD lines, polylines, and blocks
Connect to any
database & keep it in sync with
your modelConnect to shapefiles
Part 2
• Getting familiar with StormCAD
A little more theory…Open Channel Flow
•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.
Gutter
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:
Lhzg
Vyz
g
Vy 2
22
21
21
1 22
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
Open Channel Flow Types
Normal Flow
Transition from Subcritical to Supercritical flow
Transition from Supercritical to Subcritical Flow (Hydraulic Jump)
Graphic Output
Color Coding
Annotation
Profiles
Data Management
Network Navigator
Queries
Selection Sets
Part 3
• Analysis in StormCAD
Rational MethodTo 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
Inlet Calculations
Perform inlet capture & bypass calcs using HEC-22 methods
Set up gutter
networks
Store inlet properties in an engineering
library
Multiple Scenarios
Create alternative input data sets with Alternative Manager
Model a variety of situations using
Scenario Manager
Active Topology
Before site is developed (proposed elements are inactive)
After site is developed
Viewing OutputFlexTables
Reports
PropertyGrid
MicroStation & AutoCAD IntegrationStormCAD can run inside MicroStation or AutoCAD
StormCAD BasicsMal Sharkey