Evaluating Multiple Stormwater Analysis and Design

Transcription

Evaluating Multiple Stormwater
Analysis and Design Alternatives
with StormCAD
Workshop Overview
In this workshop you will use StormCAD to analyze an existing storm sewer system.
You will add a parking lot into the system and see what kind of effect this has on the
system.
Workshop Objectives
After completing this workshop, you will be able to:
•
Use scenarios and alternatives to analyze pre- and post- development conditions
•
Compare pre- and post- development networks using active topology
•
Add contours to a network to review network results
General Instructions
As we work through the exercises in class, we will skip the shaded sections, which
describe how to input all of the data if you are starting from scratch. If you would
like to work through the full workshop on your own in the future, then you can use
these shaded sections.
1
Copyright © 2014 Bentley Systems, Incorporated
Problem Statement
Problem Statement
Use StormCAD to analyze the existing storm sewer system and then see what
happens when we add the parking lot to the system.
A starter file called MultipleAlternatives.stc has been provided to you with much of
the data already entered. However, this workshop also provides instructions for
creating the model from a new file, if desired. A background drawing called
Parking_lot.dxf is required, which will be displayed automatically when you open
the starter file.
Pipe lengths are determined from the scaled drawing and the gutter network
diagram is on the following page for bypass targets.
Local IDF Curve Data Table
Intensity, in/hr
Duration, min
10 yr
100 yr
5
6.82
8.83
10
5.45
7.02
15
4.6
5.92
30
3.33
4.53
60
2.17
3.12
All pipes except for P-O2 are reinforced concrete (RCP) with n=0.013. P-O2 is an
irregular channel with a station-depth cross-section as follows:
Station-Depth Data Table
Station (ft)
Elevation (Relative) (ft)
0
517.2
1
516.3
4
510.7
5
510.7
7
515.0
10
517.2
Use the HEC-22 Energy Method (Flat Benching) to compute energy loss through each
inlet structure and the Standard method (K=0.5) to compute energy loss at each
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Problem Statement
manhole. Match pipe crowns. The tailwater condition at the outlet is 509.00 ft.
Apply default design constraints.
Predevelopment Data
Outlet Data Table
Label
Elevation (Ground) (ft)
Elevation (Invert) (ft)
Boundary Condition Type
Elevation (Tailwater) (ft)
Outlet
509.6
508.6
User Defined Tailwater
509.0
Catch Basin Data Table
Label
Inlet Location
Longitudinal Slope (Inlet) (ft/ft)
I-1L
518.2
515.2
In Sag
I-1R
518.2
515.2
On Grade
I-2R
516.8
513.45
In Sag
I-3L
517.7
514.7
In Sag
I-3R
517.7
514.7
On Grade
0.01
I-4L
518.8
515.8
On Grade
0.01
I-4R
518.8
515.8
On Grade
0.01
0.02
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Problem Statement
Manhole Data Table
Headloss Coefficient
(Standard)
Label
Headloss Method
M-1
518.4
515.12
Standard
0.5
M-2
516.9
513.53
Standard
0.5
M-3
517.9
514.62
Standard
0.5
M-4
519.2
515.72
Standard
0.5
Transition Data Table
Label
T-1
Transition Length (ft)
517.2
510.7
1.5
Gutter Data Table
Label
Start Node
Stop Node
G-1R
I-1R
I-2R
G-2R
I-3R
I-2R
G-3L
I-4L
I-3L
G-3R
I-4R
I-3R
Conduit Data Table
Label
Start
Node
Stop
Node
Section
Size
Set Invert to
Start?
Invert (Start)
(ft)
Set Invert to
Stop?
P-1L
I-1L
M-1
12 inch
FALSE
515.20
FALSE
515.12
P-1R
I-1R
M-1
12 inch
FALSE
515.20
FALSE
515.12
P-2R
M-2
I-2R
12 inch
FALSE
513.53
FALSE
513.45
P-3L
I-3L
M-3
12 inch
FALSE
514.70
FALSE
514.62
P-3R
I-3R
M-3
12 inch
FALSE
514.70
FALSE
514.62
P-4L
I-4L
M-4
12 inch
FALSE
515.80
FALSE
515.72
P-4R
I-4R
M-4
12 inch
FALSE
515.80
FALSE
515.72
P-C1
M-1
M-2
12 inch
FALSE
515.12
FALSE
513.90
P-C2
M-3
M-2
12 inch
FALSE
514.62
FALSE
513.90
P-C3
M-4
M-3
12 inch
FALSE
515.72
FALSE
514.62
Invert (Stop) (ft)
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Problem Statement
P-O1
I-2R
T-1
P-O2
T-1
Outlet
12 inch
FALSE
513.45
FALSE
510.7
FALSE
510.7
FALSE
508.6
Catchment Data Table
Label
CM-1L
Total
Area
(ac)
0.597
% of Total
Area
Rational C
Outflow Node
20
0.9
80
0.3
I-1L (click in the field and choose
<select> to select the element in the
drawing pane.)
100
0.9
I-1R
Exercise: Calculating
time of concentration
0.04
CM-1R
Time of Concentration
(min)
7
CM-2R
0.07
100
0.9
I-2R
5
CM-3L
0.822
8
0.9
I-3L
10
92
0.3
CM-3R
0.04
100
0.9
I-3R
5
CM-4L
0.25
20
0.9
I-4L
5
80
0.3
100
0.9
I-4R
5
CM-4R
0.06
5
Problem Statement
Post-Development Data
Label
CM-1L
CM-3L
CM-PL1L
CM-PL2L
CM-PL3L
Total Area
(ac)
0.20
0.46
0.40
0.27
0.75
% of Total
Area
Rational C
Outflow Node
Time of Concentration (min)
20
0.9
I-1L
7
80
0.3
9
0.9
I-3L
10
91
0.3
25
0.9
I-PL1
10
75
0.3
37
0.9
I-PL2
8
63
0.3
17
0.9
I-PL3
10
83
0.3
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Problem Statement
Conduit Data Table
Label
Start
Node
Stop
Node
Section
Size
Set Invert to
Start?
Invert (Start)
(ft)
Set Invert to
Stop?
P-2L
I-PL1
M-2
12 inch
FALSE
513.75
FALSE
513.53
P-PL1
I-PL2
I-PL1
12 inch
FALSE
514.00
FALSE
513.75
P-PL2
I-PL3
I-PL1
12 inch
FALSE
514.80
FALSE
513.75
Invert (Stop) (ft)
Gutter Data Table
Label
Start Node
Stop Node
G-1L
I-1L
I-PL1
G-2L
I-3L
I-PL2
Label
Elevation
(Ground) (ft)
Elevation
(Invert) (ft)
I-1L
518.2
515.20
Catalog Inlet
Curb DI-3B
On Grade
0.02
I-3L
517.7
514.70
Catalog Inlet
Curb DI-3B
On Grade
0.01
I-PL1
517.0
513.75
Catalog Inlet
Combination DI-10A
In Sag
I-PL2
517.00
514.00
Catalog Inlet
Combination DI-10A
In Sag
I-PL3
517.8
514.8
Catalog Inlet
Grate DI-1
In Sag
Inlet Type
Inlet
Inlet
Location
Longitudinal Slope
(Inlet) (ft/ft)
You will need to perform the following evaluations:
•
Create a Pre- and Post-Development system with the new parking lot and
analyze the pre- and post- systems.
•
Redesign the complete system with the new parking lot storm sewer system
using the 10-year rainfall.
•
Evaluate the performance of the system designed in Part 2 for the check 100year rainfall.
Detailed steps are provided in the pages that follow.
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Creating the Pre- and Post-Development Systems
In this section you will create a Pre- and Post-Development system with the new
parking lot and analyze the pre- and post- systems.
If you are using the starter file, begin by launching StormCAD V8i Stand-Alone, and
then open the file C:\Bentley Workshop\StormCAD\MultipleAlternatives.stc. You
should then skip the shaded section below.
Pre-Development System
Exercise: Creating a new project
1. Start StormCAD V8i.
2. Create a new StormCAD V8i project.
3. Select File > Save As and name the file ParkingLot.stsw.
For this workshop, we will be using a scaled background to create the scaled
drawing.
Exercise: Adding the scaled background layer
1. Select View > Background Layers to open the Background Layers manager.
2. Right-click on the Background Layers folder and select New > File.
3. On the Select Background dialog, browse to C:\Bentley
Workshop\StormCADV8i\Starter, select ParkingLot.dxf, and click Open.
4. Click OK on the DXF Properties dialog that comes up to accept the defaults.
5. Click the Zoom Extents
button on the toolbar to bring the background
into view or select View > Zoom > Zoom Extents.
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Your drawing should now look like this:
Next, we need to enter the storm data for the project.
Exercise: Adding the storm data
1. Select Components > Storm Data to bring up the Storm Data manager.
2. Click New > User Defined IDF Table to insert a new table with the default
name User Defined IDF Table – 1.
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3. For this model, we will enter information for the 10- Year and 100- Year
storm events. With User Defined IDF Table – 1 highlighted, click the Return
Periods button and select Add Range.
4. In the Add Multiple Return Periods table, enter 10 and 100 and click OK.
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5. The storm data that we have has information for the following durations: 5,
10, 15, 30, and 60; we need to add the missing durations. Click the Durations
button and select Add Range.
6. In the Add Multiple Durations dialog that appears, make sure that the
Duration column is displayed with minutes as the unit. If the units are in
hours, right-click the Duration column heading, choose Units and Formatting
from the pop-up menu, and set the Unit to min. Click OK.
7. Enter the durations in the table as show below, and then click OK.
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8. If not using starter files, enter the rainfall data from the beginning of this
workshop into the IDF table.
-OR-
Browse to C:\Bentley Workshop\StormCAD\IDFStorms.txt and open the file
in Notepad. Copy the data to the Windows clipboard. Then, return to
StormCAD, highlight the 10 Year and 100 Year columns, and press ctrl+V to
paste the data.
9. Click Close on the Storm Data manager after you are done.
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Next, we need to create the alternatives for use in our two new scenarios. We
will need new Active Topology, Physical, Rainfall Runoff, and Hydrology
alternatives.
Exercise: Creating the active topology alternative (STARTER FILE VERSION)
SKIP TO THE NEXT EXERCISE IF YOU ARE NOT USING A STARTER FILE.
1. Select Analysis > Alternatives to open the Alternatives manager.
2. In the Alternatives manager, click the + sign to expand Active Topology.
3. Right-click on the Pre-Dev Topology alternative and select New > Child
Alternative.
4. Right-click on the new alternative and select Rename. Give it the name PostDev Topology.
Exercise: Creating the active topology alternative (NO STARTER FILE VERSION)
1. Select Analysis > Alternatives to open the Alternatives manager.
2. In the Alternatives manager, click the + sign to expand Active Topology.
3. Rename the Base Active Topology alternative to Post-Dev Topology.
4. Right-click on Post-Dev Topology and select New > Child Alternative.
5. Name the new child alternative Pre-Dev Topology.
Exercise: Creating the physical alternative
1. Click the + sign to expand the Physical alternative.
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2. Rename the Base Physical alternative to Existing Physical if this has not
already been done for you.
3. Right-click on Existing Physical and select New > Child Alternative.
4. Name the new child alternative Post-Dev Physical.
Exercise: Creating the rainfall runoff alternatives
1. Expand the Rainfall Runoff alternative.
2. Rename Base Rainfall Runoff to 10 Year.
3. Double-click on 10 Year to open the Rainfall Runoff: 10 Year dialog.
4. Set the Global Storm Event field to User Defined IDF Table-1-10 Year.
5. Click Close.
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6. Right-click on Rainfall Runoff and select New > Base Alternative.
7. Name the new base alternative 100 Year.
8. Double-click on 100 Year to open the Rainfall Runoff: 100 Year dialog.
9. Set the Global Storm Event field to User Defined IDF Table-1-100 Year and
Close.
Exercise: Creating the hydrology alternative
1. Expand the Hydrology alternative. Rename Base Hydrology to Existing
Catchments if this has not already been done.
2. Right-click on Existing Catchments and select New > Child Alternative. Name
the new alternative Post-Dev Catchments.
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3. Close the Alternatives manager.
We now need to set the Calculation Options that we will be using for our
analysis.
Exercise: Setting up the calculation options
1. Select Analysis > Calculation Options.
2. On the Calculation Options manager, rename Base Calculation Options to
Analysis if this has not already been done.
3. Right-click on Solver and select Add.
4. Name the new Calculation Option as Design.
5. Double-click Analysis and make sure that Calculation Type is set to Analysis.
6. Double-click Design and set that Calculation Type is set to Design.
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7. Close the Calculation Options manager.
Now we need to create the scenarios to utilize the alternatives that we just
created.
Exercise: Creating the scenarios
1. Select Analysis > Scenarios.
2. If you are using the starter file, the Pre-Dev, 10-Yr Storm Scenario has
already been created for you.
If you started from scratch, then right-click Base and select New > Child
Scenario, and name this scenario Pre-Dev, 10- Yr Storm.
3. Right-click on Pre-Dev, 10- Yr Storm and select New > Child Scenario.
4. Name the new scenario Post-Dev, 10- Yr Storm.
5. Double-click on Pre-Dev, 10- Yr Storm to open its scenario Properties
manager and set (or verify) the following:
Active Topology: Pre-Dev Topology
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Physical:
Existing Physical
Hydrology:
Existing Catchments
Rainfall Runoff:
10 Year
6. Double-click on Post-Dev, 10- Yr Storm and set the following:
Active Topology: Post-Dev Topology
Physical:
Post-Dev Physical
Hydrology:
Post-Dev Catchments
Rainfall Runoff:
10 Year
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7. Close the Scenarios manager.
We now need to populate the Inlet Catalog and Conduit Catalog with the inlets
and conduits that we will be using in our model.
Exercise: Importing inlet libraries (NO STARTER FILE ONLY)
1. Select Components > Inlet Catalog.
2. In the Inlet Catalog manager, click on the Synchronization Options button and
select Import from Library.
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3. On the Engineering Libraries dialog that opens up, click the + sign in front of
Inlet Libraries.
This will expand the tree and display fl-inlets.xml, va-inlets.xml, and ctinlets.xml which contain default inlets from each of those states. The ones
that we want will be from va-inlets.xml.
4. Click the + sign in front of va-inlets.xml to expand that list.
5. Scroll down the list and put a checkmark in the box in front of the following
inlets: Combination DI-10A, Curb DI-3A, Curb DI-3B, and Grate DI-1.
You can view each inlet’s properties on the right side of the Engineering
Libraries dialog as you click on them.
6. After selecting all of the above inlets, click the Select button.
This will populate the Inlet Catalog manager with the selected inlets.
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7. Click Close to the close the Inlet Catalog manager.
Exercise: Importing conduit libraries (NO STARTER FILE ONLY)
1. Select Components > Conduit Catalog.
2. On the Conduit Catalog manager, click the Synchronization Options button
and select Import from Library.
3. Click the + sign in front of Conduit Catalogs, then Conduits Library.xml, and
finally Circle to see the list of available conduits.
4. Check the box for Circle – Concrete.
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5. Click the Select button.
This will import all of the circular concrete pipe properties and sizes from the
Engineering Library into our project’s conduit library so that we may use the
data in our project.
The Conduit Catalog manager should now look like this:
6. Click Close after you are done reviewing the Conduit Catalog.
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We now need to create some Prototypes to specify default and recurring values
for our elements.
Exercise: Creating prototypes
1. Select View > Prototypes to open the Prototypes manager.
In the Prototypes manager, we will be creating prototypes for Catch Basin,
Conduit, Transition, and Outfall. Keep the default names for the prototypes.
2. To begin, right-click on Catch Basin and select New.
3. Double-click on Catch Basin Prototype – 1 to bring up the Properties
manager and set the following properties:
Inlet Type:
Catalog Inlet
Inlet:
Curb DI-3B
Inlet Location:
On Grade
Manning’s n (Inlet):
0.013
Longitudinal Slope (Inlet) (ft/ft): 0.01
Headloss Method:
HEC-22 Energy (Second Edition)
HEC-22 Benching Method:
Flat
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4. On the Prototypes manager, right-click on Conduit and select New.
5. Double-click on Conduit Prototype – 1 and set the following properties for
conduits:
Conduit Type:
Catalog Conduit
Catalog Class:
Circle - Concrete
Size:
12 inch
Set Invert to Start?:
False
Set Invert to Stop?:
False
6. Back on the Prototypes manager, right-click on Manhole and select New.
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7. Enter the following properties for Manhole Prototype – 1:
Headloss Method:
Standard
Headloss Coefficient (Standard):
0.5
8. Back on the Prototypes manager, right-click on Catchment and select New.
9. Double-click on Catchment Prototype – 1 to bring up the Properties manager.
10. In the Properties manager, set the Area Defined By field to Multiple
Subareas.
11. Click in the Subareas field. This will bring up the ellipsis
button in that
field. Click on the ellipsis button to bring up the Subareas – Catchment dialog.
12. Enter in the Runoff Coefficient column: 0.3 and 0.9.
The window should look like this:
13. Click OK to close the dialog.
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Your Prototypes manager window should now look like this:
14. Save your file and close the Prototypes manager.
Network Layout
Now we are ready to lay out the model.
To make the labeling of the elements easier, you can use the Labeling option on the
Options dialog. Set the prefix and the suffix to reflect the element labels.
In this workshop, you might consider laying out the nodes first. Insert all the inlets
with the same suffix first, and then change the Element Labeling option and lay out
the other inlets. Then connect the inlets with pipes while changing the labeling
option. Alternately, you can just lay out all of the elements and then go back and
change the labels manually to match the schematic on the following pages.
To change the labeling options mentioned above, do the following:
Exercise: Changing labeling options
(Follow the instructions to lay out only the Post-Development elements in the
network layout diagrams below. The Pre-Development elements are already
drawn for you.)
1. Select Tools > Options.
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2. On the Options manager, click the Labeling tab at the top.
3. Change the Prefix and Suffix for the Conduit, Catch Basin, Manhole, and
Catchment elements to match the screenshot below:
4. Click OK to close the Options manager.
5. Make sure that the active scenario is set to Base.
6. Lay out the system according to the schematics on the following page and
remember to match the labels to the drawing as well.
27
Without the background for easier viewing:
7. Start laying out the pipe network at M-1.
8. Select the Conduit layout tool, right-click the drawing pane and select
Manhole.
9. Click to layout M-1 move to the right and layout M-2.
10. Continue this process and make sure to use the right-click menu to select the
next element.
11. Once all the pipes are laid out, lay out the gutters, and then the catchments.
12. Make sure to re-label your elements to match above.
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13. Save your model.
After completing the drawing, we need to make the elements that do not belong
in the Pre-Development scenario inactive.
Exercise: Using active topology
1. Change the scenario to Pre-Dev, 10- Yr Storm.
2. After switching to the Pre-Dev, 10- Yr Storm scenario, select Tools > Active
Topology Selection or click the Active Topology Selection button on the
toolbar.
This will open the Select toolbar.
3. With the Select toolbar open, in the drawing, click on I-PL3, I-PL2, I-PL1, PPL2, P-PL1, P-2L, G-1L, G-2L, CM-PL1L, CM-PL2L, and CM-PL3L to select
them.
The elements will turn red to indicate they have been selected. Also, notice
that clicking on the inlets will select the connecting pipes and gutters.
4. After selecting all of the elements listed above, click the Done
the Select toolbar.
button on
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Notice that all of the inactive elements have now turned a gray color to
indicate they are inactive (or disappeared if you have the Display Inactive
Topology option unchecked in the Options manager).
5. Switch the scenario to Post-Dev, 10- Yr Storm and notice that all of the
elements become active again.
Now that we have our network we will enter the associated element data.
Exercise: Network layout of post-development elements (for use with starter
file only)
1. In the upper-left corner of the main window, use the drop-down to set the
current scenario to Post-Dev, 10-Yr Storm.
2. Lay out the elements for the new parking lot drainage as shown in the
drawing that follows. For clarity only, the pre-development elements already
present have been grayed out for you. The thinner dark lines are the pipes,
and the thicker dark lines are gutters.
Specifically, the elements you should add are catch basins I-PL1, I-PL2, and IPL3; conduits P-PL1, P-PL2, and P-2L; catchments CM-PL1L, CM-PL2L, and
CM-PL3L; and gutters G-1L and G-2L.
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3. The default labels for these elements will not match those shown in the
drawing above. To change the label, click on the element and retype the
correct Label in the Properties.
Exercise: Exploring active topology (for use with starter file only)
1. Change the current scenario to Pre-Dev, 10-Yr Storm. (You might want to
uncheck the background layer to see the network a bit better.) Note that the
new topology we just added turns gray to show that it is inactive for this
scenario. This is due to our alternative hierarchy and how the alternatives
were assigned to scenarios.
2. Open the alternative manager and explore the data for the pre- and postdevelopment topologic alternatives to see the differences.
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32
Exercise: Entering system data
1. Change the scenario to Pre-Dev, 10- Yr Storm.
2. Enter the data from the tables at the beginning of the workshop.
Be sure that the conduit start and stop nodes match what is listed in the
Conduit Data and Gutter Data tables; you may need to click the Node
Reversal button in the conduit and gutter properties grid for any conduit or
gutter for which the start and stop nodes are reversed.
If you are using FlexTables to enter the catchment data, enter multiple areas
by clicking in the Area field and select the ellipsis button to bring up the
Rational Catchment Collection dialog.
Exercise: Calculating time of concentration
1. Double-click on CM-1R to open the Properties manager.
2. Set the Tc Input Type to Composite Tc.
3. In the Tc Data Collection field, click on the ellipsis button. This will open the
TC Data Collection dialog.
4. Click the New button in the top left corner and select TR-55 Sheet Flow.
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5. Repeat step 4 using TR-55 Shallow Concentrated Flow.
6. Select TR-55 Sheet Flow in the Tc Method list and enter the following data:
Hydraulic Length:
88.0 ft
Slope:
0.004 ft/ft
Manning’s n:
0.025
2 Year 24 Hour Depth:
2.5 in
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7. Select TR-55 Shallow Concentrated Flow in the list and enter the following
data:
Hydraulic Length:
40 ft
Slope:
0.005 ft/ft
Is Paved?:
True (checked)
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8. Close the dialog.
9. The CM-1R catchment Properties manager should now look like this:
10. Double-click on P-O2 to open its Properties manager and enter the following:
Conduit Type:
User Defined Conduit
Section Type:
Irregular Channel
Material:
Bare Soil
11. Click in the Irregular Channel Section: field and click on the ellipsis button to
open the Irregular Channel dialog.
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12. Enter the following Station and Depths:
Station (ft)
Elevation (Relative) (ft)
0
517.2
1
516.3
4
510.7
5
510.7
7
515.0
10
517.2
13. Close the dialog and continue to enter the following data for P-O2:
Roughness Type:
Single Roughness
Manning’s n:
0.020
Set Invert to Start?:
False
Invert (Start) (ft):
510.70
Set Invert to Stop?:
False
Invert (Stop) (ft):
508.6
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Post-Development
The data in the following tables have changed in the Post-Development. You will
need to change the values accordingly.
Conduit Data Table
Label
Start
Node
Stop
Node
Conduit
Type
Catalog
Class
Size
Set
Invert to
Start?
Invert
(Start)
(ft)
Set
Invert to
Stop?
Invert
(Stop)
(ft)
P-2L
I-PL1
M-2
Catalog
Conduit
CircleConcrete
12
in.
FALSE
513.75
FALSE
513.53
P-PL1
I-PL2
I-PL1
Catalog
Conduit
CircleConcrete
12
in.
FALSE
514.00
FALSE
513.75
P-PL2
I-PL3
I-PL1
Catalog
Conduit
CircleConcrete
12
in.
FALSE
514.80
FALSE
513.75
38
Gutter Data Table
Label
Start Node
Stop Node
G-1L
I-1L
I-PL1
G-2L
I-3L
I-PL2
Label
Elevation
(Ground) (ft)
Elevation
(Invert) (ft)
I-1L
518.2
515.20
Catalog Inlet
Curb DI-3B
On Grade
0.02
I-3L
517.7
514.70
Catalog Inlet
Curb DI-3B
On Grade
0.01
I-PL1
517.0
513.75
Catalog Inlet
Combination DI-10A
In Sag
I-PL2
517.0
514.00
Catalog Inlet
Combination DI-10A
In Sag
I-PL3
517.80
514.80
Catalog Inlet
Grate DI-1
In Sag
Inlet Type
Inlet
Inlet
Location
Longitudinal Slope
(Inlet) (ft/ft)
Label
CM-1L
CM-3L
CM-PL1L
CM-PL2L
CM-PL3L
Total Area
(ac)
0.20
0.46
0.40
0.27
0.75
% of Total
Area
Rational C
Outflow Node
Time of Concentration (min)
20
0.9
I-1L
7
80
0.3
9
0.9
I-3L
10
91
0.3
25
0.9
I-PL1
10
75
0.3
37
0.9
I-PL2
8
63
0.3
17
0.9
I-PL3
10
83
0.3
Exercise: Entering the post-development data
1. Change the scenario to Post-Dev, 10 Yr Storm.
2. Make sure your Start Nodes and Stop Nodes for conduits and gutters are the
same as in the tables. Double-click each conduit and gutter element listed,
39
directly on the drawing, to open the element Properties manager. The Start
Node and Stop Node fields are shown in the first section. Click the Node
Reversal field ellipsis button
if necessary (an example is shown below).
3. You can use FlexTables to enter conduit, gutter and catch basin data in a
tabular format. Go to View>FlexTables to open the manager.
4. Under Tables – Predefined, double-click Conduit Table to open it.
40
5. In the FlexTable, click the Edit button
to edit the columns contained in
the table. Select Conduit Type, Catalog Class, and Size from the list on the
left, and drag to the list on the right.
6. Click OK to refresh the Conduit Flextable, and then enter the postdevelopment conduit data.
7. Use the Catch Basin FlexTable to edit Catch Basin data similarly.
8. Use the Catchment table to edit the data provided for the composite areas.
Enter the Total Areas in the Area (User Defined) column.
9. In the Rational C column, click in one of the cells, and then click the ellipses
button.
41
10. Enter the data for each catch basin in its corresponding Subareas –
Catchment table.
Exercise: Calculating the scenarios
1. After entering all of the data, go to Analysis > Scenarios to open the
Scenarios manager and choose Batch Run from the Compute menu, as
shown.
2. Check the boxes for Pre-Dev, 10-Yr Storm and Post-Dev, 10-Yr Storm, and
then click Batch to run both Scenarios.
After the calculations are complete, we want to set up some profiles to view the
hydraulic grade lines in the system.
Exercise: Creating profiles
1. Make the Post-Dev, 10 Yr Storm scenario current by selecting it in the
Scenarios manager and clicking the Make Current
button.
2. Select View > Profiles to open the Profiles manager.
3. Click the New button to create a new profile.
4. On the Profile Setup dialog that comes up, click Select From Drawing.
5. In the drawing, click on inlet I-PL3 and the Outlet. Pipes P-PL2, P-2L, P-2R, PO1, and P-O2 will be automatically selected and will appear red.
42
6. After you have selected all of the pipes, click the check mark button
the Select toolbar.
on
7. All of the pipes and nodes that you have selected will now be listed in the left
side of the Profile Setup dialog.
8. Click the Open Profile button to view your profile. You should see the profile
below, although you may notice slight variations due to differences in inlet
placement.
43
9. Close the profile.
10. Back on the Profiles manager, rename the profile. Right-click on Profile:
Profile – 1 and select Rename. Rename the profile to I-PL3 to Outlet.
We will need to create 2 more profiles: I-1L to Outlet and I-4L to Outlet. We
could repeat the steps above to create the profiles. However a quicker
method is as follows:
11. In the drawing, right-click on I-1L and select Create Profile…
12. On the Create Profile dialog, name this profile I-1L to Outlet, and then click
OK. This will create and open a profile that includes all of the pipes and nodes
from I-1L to the Outlet.
13. Repeat this process to create a profile on I-4L named I-4L to Outlet.
44
14. Look in the Profiles manager again; observe that it lists all three of the
profiles that we just created.
15. Looking at each of the profiles, note that there is significant surcharging
during this 10 year storm event for post-development conditions.
16. Change the scenario to Pre-Dev, 10 Yr Storm and look at the I-1L to Outlet
profile. It should look like the following:
45
Redesigning the System
You can enable annotation on the profile by selecting the down arrow next to
the Chart Settings
button and clicking Display Annotation Labels.
Note that, in general, the predevelopment has enough capacity except for a
small amount of surcharge around M-2, but the post-development condition has
more significant surcharging.
In the next section, we will redesign a portion of the existing system to enable
better performance with post-development flows.
In this section you will redesign the proposed (post-development) structures and
existing pipes P-2R and P-01 using the 10-year rainfall event.
First, we need to make only the desired pipes available for design. We don’t want to
use anything smaller than 12-inch diameter pipe.
Exercise: Setting up conduits available for design
1. Select Components > Conduit Catalog
2. In the Conduit Catalog, on the table in the Conduit tab, de-select Available for
Design for the 8-inch and 10-inch pipes.
46
3. Close the Conduit Catalog.
We also need to make adjustments to the Base Design Alternative.
Exercise: Changing the base design alternative
1. Click Analysis > Alternatives to open the Alternatives manager.
2. Expand the Design alternative and double-click Base Design.
3. In the Design Constraints Alternative: Base Design dialog’s Gravity Pipe tab,
verify that the Velocity (Minimum) is 1.0 ft/s.
4. Click the Cover sub-tab, and verify that Cover (Minimum) is 2 ft.
5. Click the Slope sub-tab, and verify that Slope (Minimum) is .005 ft/ft.
6. In the table, right-click the Design Conduit column heading, select Global
Edit, observe that the Value will be set as unchecked (FALSE), and click OK.
47
7. Check the boxes for existing pipes P-2R and P-O1, and proposed pipes P-2L,
P-PL1 and P-PL2 as shown in the image below. Note that we will not design
the Stop Invert for P-O1, so that we can hold the elevation where it
discharges to the existing downstream channel.
8. Click the Node tab.
9. Set Pipe Matching to Inverts.
48
10. In the Gravity Structure table, Global Edit the Design Structure Elevation
column so that all boxes are unchecked.
11. Check the Design Structure Elevation box for M-2, I-2R, I-PL1, I-PL2, and I-PL3
(the structures attached to the pipes we’re redesigning). This will allow the
invert of the structure to be matched to the pipe invert elevation.
12. Click Close and then close the Alternatives manager also.
We will now create a new scenario for the design.
Exercise: Creating a new scenario for the design
1. Select Analysis > Scenarios.
2. Create a new child scenario under Post-Dev, 10-Yr Storm.
3. Name the new child Post-Dev 10-Yr Redesign.
4. Double-click on Post-Dev 10- Yr Redesign and set Solver Calculation Options
to Design in the Properties manager.
49
6. Change the current scenario to Post-Dev 10 Yr Redesign.
Exercise: Calculating the model
1. Select Analysis > Compute to run the model.
2. On the Post-Dev 10- Yr Redesign: Design Calculation dialog that comes up,
click Yes to create a new physical alternative.
3. Name the new physical alternative Post-Dev Redesign and click OK.
4. Close the Calculation Executive Summary dialog.
5. Check the profiles now for this scenario.
50
In general, there is now adequate capacity in the system with this new design.
51
Evaluating the New System
In this section you will evaluate the performance of the system designed in Part 2 for
the check 100-year rainfall.
Exercise: Creating and computing the 100 yr storm scenario
1. Open the Scenarios manager.
2. Create a child scenario of Post-Dev 10 Yr Redesign.
3. Name the new child scenario Post-Dev 100 Yr Redesign.
4. Set the Rainfall Runoff alternative to 100 Year.
5. Since we are only analyzing—not designing—for the 100-year event, also
change the Gradually Varied Flow Calculation Option to Analysis.
7. Change the active scenario to Post-Dev 100 Yr Redesign.
8. Compute this scenario.
52
9. Click the Messages button on the Calculation Executive Summary dialog to
review the User Notifications.
10. Close the User Notifications and Calculation Executive Summary dialogs after
you are done reviewing the messages.
11. Look at the profiles for this scenario.
12. In general the 100 yr storm will cause many of the pipes to become
surcharged, but there is no external flooding of the system.
53
Questions
Questions
1. What is the maximum spread in the system for the 10-year and 100-year events
after redesigning the system in Part 3? Where does this occur?
2. How much of the system pressurizes during the 100 yr redesign scenario (list
pipes)?
3. You should create a new StormCAD file for each different design option.
4. Describe the primary use of the Active Topology tool.
5. Describe the best time to make use of Prototypes:
54
Answer Key
Answer Key
1. What is the maximum spread in the system for the 10-year and 100-year events
after redesigning the system in Part 3? Where does this occur?
Maximum spread occurs at I-3L for the 10-year storm, and is 10.6. Max spread
for the 100-year event occurs at I-PL3 and is 12.1 ft. (Inlets may be added to
reduce spread.)
2. How much of the system pressurizes during the 100 yr redesign scenario (list
pipes)?
P-C1 and P-C3 are partly pressurized. P-2R, P-2L, P-PL2, P-C2 and P-PL1 are fully
pressurized.
3. You should create a new StormCAD file for each different design option.
False – it is much better to create a new scenario in the same StormCAD file.
4. Describe the primary use of the Active Topology tool.
The Active Topology tool is used when some elements are only present in
certain scenarios. For example, if you are connecting a new subdivision to an
existing stormwater system, you may wish to set up a scenario showing the
system before development, then another scenario showing the system after
development. You would then use the Active Topology tool to make the new
subdivision elements inactive in the ‘before development’ scenario.
5. Describe the best time to make use of Prototypes:
Prototypes are most useful when you need to manually lay out many elements
that share a number of similar properties – typically at the start of a new
project.
55

Evaluating Multiple Stormwater Analysis and Design

Transcription

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