Introduction to Autodesk Storm and Sanitary Analysis

Transcription

1 Charlie Ogden, P.E. Autodesk, Inc. CI4352-L & CI6901-L This hands-on lab focuses on the interface of Autodesk Storm and Sanitary Analysis software and its capabilities. A special emphasis will be made on using stormwater data from AutoCAD Civil 3D software. The class will cover workflows for exporting a model from Civil 3D into Storm and Sanitary Analysis and performing an analysis. If you design pipe networks and you have been wondering how to start using this analysis tool, then this class is for you. Learning Objectives At the end of this class, you will be able to: Use the Storm and Sanitary Analysis interface to successfully set up and model a stormwater system Share model information between Civil 3D and Storm and Sanitary Analysis Identify the capabilities and limitations of Storm and Sanitary Analysis using Civil 3D data Analyze stormwater runoff, pipe networks, bypass, and detention ponds About the Speaker Charlie Ogden is a Sr. Quality Assurance Analyst at Autodesk, and a Professional Engineer licensed in Massachusetts. Prior to joining Autodesk, Charlie was a Solutions Specialist at a leading Autodesk reseller, providing Civil 3D implementation, consulting and training services for engineers and firms across the USA. He has 16 years of civil engineering and surveying experience, including residential subdivisions, commercial site plans, storm water management, and sewer and septic system designs. He holds a Bachelor of Science degree in Civil and Environmental Engineering, and an Associates of Science degree in Architectural Engineering Technology. He is a Civil 3D Implementation Certified Expert, and a Civil 3D Certified Professional. charlie.ogden@autodesk.com

2 Table of Contents Learning Objectives... 1 About the Speaker... 1 Intended Audience... 2 Introduction to Autodesk Storm and Sanitary Analysis (SSA)... 3 User Interface... 3 Project Options... 4 Analysis Options... 4 Lab Exercise #1: Perform Analysis & Review Results... 4 Basic Modeling with SSA Elements... 7 Project Elements... 7 Rainfall... 8 Lab Exercise #2: Create a basic model Sharing model data between Civil 3D and Storm and Sanitary Analysis...15 Exporting Civil 3D Data...16 SSA Part Matching...16 Lab Exercise #3: Analyze a Civil 3D model...17 Modeling Storage Nodes...22 Creating Storage Nodes...22 Storage Outlets...22 Lab Exercise #4: Defining Storage Nodes...25 Additional Information:...28 Intended Audience This is a beginner level hands-on lab meant for designers looking to start using this analysis tool for their stormwater designs. A basic understanding of hydraulics and hydrology is recommended as class time will not allow for in-depth coverage of those topics. During the lab users will utilize AutoCAD Civil 3D as well as Autodesk Storm and Sanitary Analysis. No prior use of either application is required. The class will not cover creating model data in AutoCAD Civil 3D, but only on the analysis of such data from an existing drawing. 2

3 Introduction to Autodesk Storm and Sanitary Analysis (SSA) This class will introduce users to the use Autodesk Storm and Sanitary Analysis ( SSA ) for analysis of stormwater networks. The main focus will be on modeling network data within SSA. A stormwater model can either be created from scratch within SSA or imported from various sources such as AutoCAD Civil 3D, AutoCAD Map 3D, or GIS data. SSA allows users to model stormwater networks using various hydrology and hydraulic computational methods; it can also be used to model sanitary sewer networks. First off, there are a few ways to launch SSA: 1. Autodesk Storm and Sanitary Analysis shortcut on the desktop; 2. StartSSA Command within Civil 3D - which simply launches SSA; 3. EditInSSA command within Civil 3D - this launches SSA and transfers Pipe Network data. User Interface 3

4 Project Options Assign the hydrology and hydraulic routing methods as well as default settings for elements to be used for the project. The following shows some of the available methods: Hydrology Methods: Time of Concentration methods: Hydraulic Routing Methods: EPA SWMM Rational Modified Rational Santa Barbara UH SCS TR-20 SCS TR-55 HEC-1 UK Modified Rational Carter Eagleson FAA Harris County, TX Kirpich Papadakis-Kazan SCS TR-55 User-Defined Hydrodynamic Kinematic Wave Steady Flow The User Guide discusses each of these methods in detail. Analysis Options Assign the time step settings as well as the design storms to be calculated. Time Steps & Storm Duration Storm Selection o Rain Gage - Rainfall Time Series (used for most hydrology methods) o IDF Curve (used for Rational methods) Lab Exercise #1: Perform Analysis & Review Results 1. Launch SSA from the desktop shortcut. 2. Open TR-20.spf a. File > Open b. C:\Program Files (x86)\autodesk\ssa 2013\Samples\Hydrology Methods\TR- 20.spf 3. Save the file to the Desktop (Please don t save any changes to the original sample file) a. File > Save As b. File name: Lab1 c. Select Save 4. Explore the Menus 5. Explore the Toolbars (hover over the icons to reveal the command name) 6. Explore the Data Tree (the tree lists the types of data that could be in a model) 7. Explore the Plan View canvas (model view) 8. Select Input > Project Options 9. On the General tab, confirm that the following are set - make changes where required. a. Units System US Units 4

5 b. Hydrology Method SCS TR-20 c. Time of concentration (TOC): Kirpich d. Link routing method Hydrodynamic 10. Explore the settings on the ID Labels tab (used to name new elements) 11. Explore the settings on the Element Prototypes tab (used to provide default values) 12. Select OK to close the dialog box 13. Select Analysis > Analysis Options 14. On the General tab, review the Time steps and Dates: Start and End Analysis on times. 15. On the Storm Selection tab see that the selected storm uses the assigned rain gage instead of a specific rainfall time series. (more on this in lab exercise 2) 16. Select OK to close the dialog box 17. Perform Analysis a. Use either the Perform Analysis button ( ) or from the menu: Analysis > Perform Analysis b. Select OK 18. Find the pipe labeled 6 (see image below). The red highlight indicates that the link is surcharged. The blue highlight on the connected structure indicates that it has flooded. 19. Double-click on the blue junction, and find the following: a. The invert elevation b. The rim elevation c. The Max water depth & elevation 20. Next review the Analysis summary (results): a. The red highlighted boxes indicate warning or errors. The junction has flooded; the water depth has risen to the rim elevation and overflowed. 21. In the table at the bottom of the dialog box, select ID 9 (row 1 - see image below). 5

6 a. Use the up and down arrows on your keyboard to scroll through the results of all the other Junctions in the model. The values in the dialog box will change to reflect those for the element selected in the table. Close when finished. 22. Double-click on the red pipe labeled 6, and review the information in the dialog box, and find the following: a. The link type and shape b. The link s size: diameter & length c. The link s invert elevations & slope 23. Next review the Analysis summary (results): a. The red highlighted boxes indicate warnings or errors. Notice that the link is marked as Surcharged and the peak flow during analysis is greater than the design flow capacity. 24. Increase the pipe s diameter to 15 (do not press <enter> - instead click in a different cell) and notice the change to the Design flow capacity, if it s still not larger than the Peak flow during analysis value, then increase it until it is, then press Close. 25. Select Perform Analysis ( ) again. 26. Review the results for the link again: 27. Change diameter to 18, and Perform Analysis ( ) - The Conveyance Links dialog box can remain open while performing the analysis, but you ll need to pick inside a cell to see the values update. 6

7 28. At the bottom of the Conveyance Links dialog box select ID 1 (row 1), and review the Analysis summary for any warnings. 29. Use the up and down arrows to scroll through the results of all the other Conveyance Links in the model. 30. Please Do NOT Save changes to the original sample file (we want the next Lab to see the original values). Thank you. 31. STOP Basic Modeling with SSA Elements Project Elements Now let s look at some of the element types that we can model in Storm and Sanitary Analysis. System modeling in SSA is node-link-node based, so link elements are used to connect nodal elements. Many elements can be added to the model using the Elements toolbar: Subbasins Subbasins are used to model the drainage areas for runoff flowing into the stormwater model. Later we ll see that Catchment objects from Civil 3D will be imported as Subbasins. Values must be specified for drainage area, runoff coefficient (or curve number) and time of concentration. Connect the subbasins to Inlet elements using the following: Right-click on a Subbasin > Connect To > select the Inlet 7

8 Inlets Stormwater Inlets can represent many different inlet types, including FHWA generic types, as well as inlets by specific providers. Specifications will need to be selected to define the type, size and location of the inlet, invert and rim elevations, and roadway gutter specifications. Inlets on grade (as opposed to in a sag) will require bypass links be specified in order to route any over-capacity flows past the inlet. Junctions Junctions are typically used to model manhole structures. But SSA uses a node-link-node model so Junctions are also used simply as computation points between links. For example, Junctions would be required at the start and/or end of culverts that have headwalls, endsections, or simply open ended pipe without a real structure. Conveyance Links Conveyance links can model pipes, culverts, channels, or direct connections between nodes. Outfalls An Outfall is another type of node element that exists at the end of a network. Rainfall Rainfall data needs to be specified for the subbasins. For the Rational methods, the user will set IDF curves to be used. All other hydrology methods will use a Rain Gage to assign a rainfall time series. IDF Enter IDF curve data based on standard equations as well as direct entry of a single intensity, or a table of intensity values. 8

9 Rain Gage Use the Rainfall Designer to assign standard rainfall data. Typical rainfall depths are available for each county in the United States. Many Storm Distribution curves are available as well, including the various SCS curves. Lab Exercise #2: Create a basic model. 1. Import the background image a. Launch SSA from the desktop shortcut (if it s not still open) b. File > New (don t save the current file if it s still open) c. View > Layer Manager d. Select the ellipses ( ) for Image/CAD file: e. Browse to and open: <lab_dataset_location>\dataset\conceptual\conceptdrainage.tif f. Notice that the World coordinate file is also located. g. Select OK h. The image should be brought into the Plan View canvas. This is a screen capture from an Autodesk Infrastructure Modeler conceptual design, but you could also use an AutoCAD DWG file as a background - as we ll see later. i. You could use the measurement tools ( ) to see that the image is sized realistically. 9

10 Note: It is not necessary to use geo-referenced images for realistic dimensions because areas and lengths can be entered directly. However, it does make things easier! 2. Setup the Project Options a. From the menu: Input > Project Options b. Select the following options on the General tab: Unit System: US Units Flow units: CFS Elevation type: Elevation Hydrology Method: SCS TR-20 Time of Concentration: SCS TR-55 Minimum allowable TOC: 5 min Link Routing Method: Hydrodynamic c. Select OK 3. Create a Subbasin: For simplicity, let s assume we need to fill in the island created by the three roads to add new homes. Assume runoff on this area still flows toward the new road a. Select the Add Subbasin icon ( ) b. Trace the centerline of the roads to create a closed shape for the subbasin. Double-click on your last point to end drawing the subbasin. 10

11 Right-click anywhere and choose Select Alternative: Add the subbasin with a double-click in canvas, and manually enter the area (a default area will be used initially). This is helpful if the shape or size of the subbasin cannot be traced. Note: Double-clicking to create other elements will actually create two. 4. Let s create a simple network consisting of an Inlet, a Junction and an Outfall before the detention pond. Something like this: 11

12 5. Create the Inlet: a. Select the Add Inlet icon ( ) b. Select the desired location in canvas. c. Select <Esc> to exit the Add Inlet command. 6. Create the Junction: a. Select the Add Junction icon ( ) b. Select the desired location in canvas. c. Right-click and choose Select to exit the Add Junction command. 7. Create an Outfall: a. Select the Add Outfall icon ( ) b. Select the desired location in canvas. c. Select <Esc> to exit the Add Outfall command. 8. Connect Pipes between the nodes: a. Select the Add Conveyance Link icon ( ) b. Select the Inlet, and then the Junction c. Reselect the Junction, and then the Outfall d. Right-click and choose Select to exit the Add Conveyance Link command. 9. Edit the Subbasin a. Double-click on the Subbasin and change the following on the SCS TR-55 TOC tab: Sheet Flow: o Manning s roughness 0.40 o Flow length: 100 o Slope: 2 o 2yr-24hr rainfall: 2.7 [Select the ellipses ( ) and choose New Hampshire & Sullivan County] Shallow Concentrated Flow: o Flow length: 300 [or use ellipses ( ) to pick a. length on the site image] o Slope: 2 o Surface type: Short grass pasture Curve Number tab: o Select the ellipses ( ) in the Curve Number column 12

13 o Find: Open space > grass cover > 75%, Good, Soil group B. (should be 61) o Double-click the number to select it. b. Select Close c. Right-click on the Subbasin and choose Connect To, then pick the Inlet. 10. Edit the Inlet: a. Double-click on the Inlet and change the following properties: Inlet Type: Combination Inlet Inlet location: On Sag Curb opening and grate type: Sweeper Inlet Grate width: 36 Curb opening length: 72 Catchbasin invert elevation: Inlet Rim elevation: b. Select Close 11. Edit the Junction: a. Double-click on the Junction and change the following properties: Invert elevation: Max/rim elev: b. Select Close 12. Edit the Conveyance Links: a. Double-click on the link between the inlet and junction and change the following: Length: 300 Inlet invert elevation: select the Match Inlet Junction Invert button. ( ), or manually enter 95. Outlet invert elevation: select the Match Outlet Junction Invert. button ( ), or manually enter 91. Diameter: 24 inches b. At the bottom of the dialog box select row 2, then change the following: Length: 190 Inlet invert elevation: select the Match Inlet Junction Invert button. ( ), or manually enter 91. Outlet invert elevation: Manually enter 88. Diameter: 24 inches c. Select Close 13. Edit the Outfall: a. Double-click on the Outfall and change the invert elevation to Create a Rain gage a. Select the Add Rain Gage icon ( ) b. Select a location anywhere off to the side of our image in the canvas. 13

14 c. Right-click and choose Select to exit the Add Rain Gage command. d. Double-click on the Rain Gage e. Under Data source, select the ellipses ( ) next to Time series: f. In the Time Series dialog box, select the Add button in the top right. g. Under Time series data, select the Rainfall Designer h. Under Unit intensity select the check box for an SCS Type II 24-hr storm i. Confirm that the State & County are set to New Hampshire & Sullivan j. Set the Return period to 10 years k. Select OK, and then Close the Time Series dialog box l. In the Rain Gages dialog box select Assign and choose Yes to assign the rain gage to all subbasins. m. Close the Rain Gages dialog box. 15. Analysis Options a. General tab: change End analysis on to tomorrow s date (11/30/2012) b. Storm Selection tab: pick either option under Single storm analysis, both will be ok since there s only one rainfall time series in the model and it s assigned to the rain gage. c. Select OK. 16. Perform an analysis: a. Select the Perform Analysis button ( ) b. Select OK 14

15 17. BONUS (if time remains): Determine a preliminary size for a detention basin: a. Select the Time Series Plot button ( ) found below the Plan View tree in the bottom left of the application. b. In the Time Series Plot tree expand Nodes > Total Inflow c. Select the Outfall (Out-01) d. In the Total Inflow Summary Table below the canvas, enter the Max flow allowed as 10. e. Press Enter (then hover mouse over the plot area so that numbers update). f. The required Detention Storage is reported in the table, and displayed as the cyan shaded area on the Time Series Plot. 18. STOP Sharing model data between Civil 3D and Storm and Sanitary Analysis A recommended approach for using these products together harnesses the stronger abilities of each product to best perform a design. Creating Catchments, Pipe and Structure elements in Civil 3D instead of in SSA can take advantage of other model elements in a way that SSA cannot (for example, surface elevations, alignment stations and offsets, and full profiles). Pipe Network rules can be used for initial pipe inverts and slopes. However, some hydrology and hydraulic properties (e.g. inlets, and channels) are more appropriately entered in SSA which allows for the detail needed to perform an analysis. Profiles within SSA only show ground data by connecting the rim elevations of structures, and therefore do not show the full profiled surface between structures; and there s no terrain model. Some other tools within Civil 3D are worth noting as they can be used to gather important information for analysis from the Civil 3D model that is not readily available inside of SSA. 1. Water Drop: to assist with Catchment placement; 2. Stage Storage Tool: to calculate storage volumes; 3. Hydraflow Hydrographs: Pond tools to calculate complex Stage-Discharge data 15

16 Exporting Civil 3D Data The data transfer method between Civil 3D and SSA uses Autodesk s Hydraflow Storm Sewers data file, so Civil 3D uses the same settings that it uses to transfer data to and from Hydraflow Storm Sewers. It is also important to understand how SSA transfers data to and from this file. This file has an extension of.stm and I may refer to it as an STM file. Please note that actual use of Hydraflow Storm Sewers is NOT required for this data transfer. Some important details of the settings used within Civil 3D and SSA are described below. Storm Sewers Migration Defaults These defaults control how Civil 3D exports and imports STM file data. These settings are accessed from the Settings tab. Part Matching Defaults Controls the matching between Civil 3D Part Family s and Storm Sewers Part Types for both Import into Civil 3D and Export from Civil 3D. Parts List Used for Migration A best practice is to select a Full Parts List for Migration. This will ensure that all Part Families and default sizes are available when importing data from an STM file. Allow Part Family Swapping Turning this off will allow you to avoid matching to an unexpected family. For example, if you have a mixed material network (some concrete pipes and some plastic pipes) you won t want all your pipes reimported as concrete pipe because the Storm Sewers file and SSA only recognize the shape of pipe, not the material. Use Imported Part ID for Part Family This option would only be used for advanced part matching that uses an XML file to more directly match Part Family s to SSA Part Types. Unfortunately due to time constraints this is beyond the scope of this course (see note at bottom of page 17). SSA Part Matching SSA must make an interpretation between the Storm Sewers part types and the available SSA elements. The Storm Sewers format is limited to only ten (10) different part types. There are many more types available in SSA. When importing and exporting STM files, SSA will assign an element and/or inlet type based on the following chart (reading from left to right shows the STM part types exported from Civil 3D that become SSA parts upon import, and then the exported STM parts that will be imported into Civil 3D. ** denotes items that will not round-trip. 16

17 STM Part Type Exported from Civil 3D Corresponding SSA Part Type STM Part Type Imported into Civil 3D Manhole Junction Manhole Combination Inlet Inlet - FHWA Combination Combination Inlet Curb Inlet Inlet - FHWA Curb (on Grade) Curb Inlet Grate Inlet Inlet - FHWA Grate (Rectangular) Grate Inlet Drop Grate Inlet - Median & Ditch Drop Grate Drop Curb Inlet - FHWA Curb (on Sag) Drop Curb Generic Headwall Junction (or Outfall if end of run) Generic Manhole** No Structure Junction Manhole** Outfall Outfall Outfall N/A Inlet - FHWA Grate (Circular) Grate Inlet N/A Storage Node Manhole N/A Diversion Manhole Advanced: There is also a part matching XML file that can be created to better control matching parts between Civil 3D or Map 3D and SSA. This is beyond the scope of the lab, but more information can be found in the Civil 3D User s Guide under: Catchments and Flow Path Analysis > Analyzing Catchments in Storm and Sanitary Analysis > Part Matching Between AutoCAD Civil 3D and Storm and Sanitary Analysis. Lab Exercise #3: Analyze a Civil 3D model 1. Open the Civil 3D drawing a. Launch Civil 3D b. File > Open c. Open: <lab dataset location>\dataset\civil3d\ _AU2012Lab-A.dwg 2. Examine a Catchment and it s connected part 17

18 a. On Prospector expand Catchments > Proposed b. Select CB-7, right-click and choose ZoomTo c. From Prospector, right-click on CB-7 again and choose Properties d. Find the Reference Pipe Network Structure property and verify that it s value is CB-7 e. Familiarize yourself with the other properties and then select OK. 3. Examine Pipe Network parts used a. On Prospector expand Pipe Networks > Networks > StormDrains_C b. Select Structures c. In the Item Preview list select CB-7, right-click and choose Structure Properties d. On the Part Properties tab find Part Data > Part Description i. It should be a Concentric Cylindrical Structure, select OK e. Repeat the above steps for MH-106 i. It should be an Eccentric Cylindrical Structure, select OK 4. Review the Part Matching settings a. Select the Settings tab of Toolspace b. Right-click on Pipe Network and choose Edit Feature Settings c. Expand Storm Sewers Migration Defaults d. Select in the empty cell for Part Matching Defaults, and then press the ellipsis e. Change to the Export tab and view the settings for our part types, and make the following changes if necessary: i. Concentric Cylindrical Structure: Combination Inlet Rectangular ii. Eccentric Cylindrical Structure: Manhole Circular f. On the Import tab confirm that the above matching is set in the opposite direction by making the following changes, if necessary: i. Combination Inlet Rectangular Concentric Cylindrical Structure ii. Combination Inlet Circular Concentric Cylindrical Structure iii. Manhole Circular Eccentric Cylindrical Structure iv. Manhole Rectangular Eccentric Cylindrical Structure g. Select OK, and then OK again 5. Analyze the network in Storm and Sanitary Analysis a. From the ribbon, select Analyze > Edit in Storm and Sanitary Analysis ( ) b. Confirm that the three Pipe Networks are selected, and press OK. 18

19 c. Once SSA opens, select OK to Create a new project wait for it to import. d. Select No, not to save the log file e. Select the Plan View tab and you should see the Civil 3D model in the canvas with SSA elements for the network parts. f. Find and Review the following elements that were imported: i. Subbasin CB-7 double-click the element type from the Data Tree ii. Inlet CB-7 find the element in the list, then pick Show iii. Pipe - (73) 6. Setup the Project Options: before we can analyze the network we must setup the model a. Double-click on Project Options on the Plan View tree (or use Input > Project Options) b. Confirm that the model is using: i. Hydrology Method: Rational ii. Time of Concentration: SCS TR-55 19

20 c. Change the following: i. Link routing method: Hydrodynamic d. Select OK 7. Setup the Analysis Options a. Double-click on Analysis Options on the Plan View tree (or Analysis > Analysis Options) b. Change the End Analysis on: time to 03:00:00, so the Analysis Duration is 3 hrs: c. On the Storm Selection tab Use return period 2 years. d. Select OK. 8. Perform Analysis a. Perform Analysis ( ) b. There may be a number of surcharged pipes (highlighted red) and flooded structures (highlighted blue). For now let s just fix a few 9. Edit the model: Let s make some changes to some of the elements in the model: a. Subbasins: i. From the Plan View tree double-click on Subbasins ii. Find Subbasin CB-7 in the list at the bottom of the dialog box, and select the Show button in the top right - this will highlight the subbasin in the canvas zoom in to the network fed by this subbasin. iii. Edit the two Subbasins so that the runoff coefficients are 0.50 b. Inlets CB-7 & CB-8 i. Equal Length Inlet, change to: Sweeper Inlet ii. Grate width: 48 (double grate into the road) iii. Curb opening length: 72 iv. Gutter Depression: 3 c. Change the pipe diameters for the following pipes (Conveyance Links): i. Pipe-(72): 18 ii. Pipe-(73): 24 iii. Pipe-(74): 24 iv. Pipe-(75): 24 v. Pipe-(76): 18 d. Perform the Analysis ( ) again 10. Profile Plot: Let s view a profile of the network: a. Select the Profile Plot button ( ) below the data tree 20

21 b. Select Inlet CB-7 for the starting point, c. Select the Outfall at the end of the run as the ending point d. Right-click and choose Show Plot: e. Select Output > Output Animation f. Press Play ( ) BONUS (if time remains): 11. Export changes back to Civil 3D a. File > Export > Hydraflow Storm Sewers File b. Give the file a name and save it where you can find it. c. You can select No, not to save the log file. d. File > Save the Storm and Sanitary Analysis file for the next Lab exercise. 12. Import changes back into Civil 3D a. From Civil 3D ribbon: Insert > Import > Storm Sewers b. Browse to the file you just exported from SSA c. Select Update the existing pipe network d. You ll see messages regarding the Outfalls not being matched exactly - that s because the STM file used to transfer the data does not retain the outfall size. 13. STOP 21

22 Modeling Storage Nodes Storage nodes are network elements with associated storage volume. They can represent storage facilities as small as a catchbasin, or more commonly as a detention pond, and as large as a reservoir or lake. They can represent open surface storage or sub-surface storage. Creating Storage Nodes There are two types of Storage Node definitions in SSA: Functional type is used to define the relationship between the surface area and depth using the following formula: Area = (Constant Surface Area) + B * Depth C For storage tanks (and other fixed footprint structures with vertical walls) only the Constant Area entry is specified (ft 2 or m 2 ), the Coefficient B and Exponent C values need to remain blank (or entered as 0). Storage Curve type allows the user to define the relationship of area or volume per depth (or stage). The curve created by this data is known as a Stage-Storage Curve. The stage values are a depth in the pond instead of an actual elevation value. This makes the curve reusable for other storage nodes, and also easier to raise and lower, since it's independent of the surface elevations. Results from Civil 3D's Stage Storage calculations can be used to define this curve. Storage Outlets Various elements can be used to model discharge from a storage node. There could be multiple elements used in combination in order to control discharge for different storm events. Available outlets include Conveyance Links, Weirs, Orifices, generic Outlets, and Exfiltration. Weirs Weirs can be used either as part of an emergency spillway, or part of an outlet structure. In SSA they are represented as a link connecting two nodes, where the weir itself is located at the upstream node. Some typical shapes that can be modeled with SSA are shown below: V-Notch Trapezoidal (& Rectangular) 22

23 Side Flow Transverse Orifices Orifices are often used to control the rate of flow out of a pond. They are often cut into a concrete wall or structure as a certain size and elevation to best control the outflow for a particular storm event. They are often used as part of an outlet structure. In SSA they are represented as a link connecting two nodes, where the orifice itself is located at the upstream node. They can be either a circular or rectangular shape in the side or bottom of the wall. Side Bottom Outlets Outlets are flow control devices that cannot easily be characterized by pipes, orifices, or weirs. They are modeled by either a discharge function or a stage-discharge rating curve. This makes it easy to model any special outlet for which this discharge information is known. 23

24 Exfiltration Exfiltration refers to the flow of water out of the pond as it infiltrates into the ground below. The method of exfiltration is set for the project in the Project Options dialog box. The available options are: Constant Flow Rate a value in cubic feet per second or cubic meters per second. Constant Exfiltration Rate an average rate in in/hr. or mm/hr. Horton Exfiltration Method A more complex method that models the decreasing rate of exfiltration over time as the soil becomes more saturated. The actual properties for each Storage node are defined inside the Storage node dialog box. The user sets where and when the exfiltration occurs, and specifies a value. No Exfiltration - No exfiltration losses will occur from the detention pond structure. At All Elevations - Exfiltration losses will be considered to occur for all water surface elevations within the detention pond structure. Above Elevation (or Above Depth) - Exfiltration losses will occur above the specified elevation (or depth). This commonly occurs when there is a pond liner to maintain a minimum water surface elevation within a basin - such as a wet retention pond. 24

25 Lab Exercise #4: Defining Storage Nodes 1. Let s determine the size of a detention basin in the Civil 3D drawing and model it in SSA: a. Reopen the Civil 3D drawing (if not still open) b. Restore the saved view StormBasin2 : View (tab) > Views (panel) > StormBasin2 2. Use Stage Storage tool: a. Analyze > expand the Design panel > Stage Storage b. In the Stage Storage do the following: i. Fill in the Report Title, Project Name, & Basin Description ii. Select Average End Area for Volume Calculation Method iii. Select Define Basin button ( ) c. In the Define Basin from Entities dialog box: i. Enter a Basin Name (i.e. Basin #2) ii. Select the Define button ( ) d. At the prompt select any proposed contour line within the blue outline for Basin 2. e. The table should get filled in: f. Select Save Table ( ) g. Give the table a name and save it where you will find it for the next step. h. Close the Stage Storage dialog box ( ) 25

26 3. Create a storage node in SSA a. If you ve already closed SSA project from the previous exercise, then do the following, otherwise continue to step b. i. At the Command line in Civil 3D enter: STARTSSA ii. Press <Enter> iii. Open the project from the previous exercise, or alternatively you may open: \DATASET\Civil3D\_AU2012Lab-B.spf b. Zoom to the area near Basin 2 (or MH-108) c. Add a Storage Node in the center of the basin using the Add Storage Node button ( ) d. Right-click and choose Select e. Double-click on the new Storage Node, and change the following: i. Invert elevation: ii. Maximum elev: iii. Type: Storage. Curve f. Select the ellipses next to the Storage curve property g. In the Storage Curves dialog box: i. Select Add ii. Select Load iii. Change Files of Type to: iv. Browse to and open the Stage Storage Table saved from Civil 3D Alternative: you may load the file: \Dataset\Civil3D\Basin2.AeccSST v. Select Close, and then Close again to get back to the Plan View. 4. Route the Pipe Network through the Storage Node. The current Outfall should be a Junction, and connected to the Storage Node with a Direct Conveyance Link. 26

27 TIP: If possible retain the Outfall imported from Civil 3D as an Outfall so that when imported back to Civil 3D it will be recognized as the same Pipe Network. So we ll create a new junction, connect the existing pipe to it, and move the outfall. a. Select the Outfall ( ) near Basin 2, b. Right-click and choose Duplicate, c. Pick a point next to the original location. d. Right-click the new Outfall and choose Convert to > Junction e. Select the Conveyance Link connected to the Outfall, f. Right-click and choose Connect From/To g. Pick the upstream Junction and then the new Junction. h. Move the Outfall to a location to the west of Basin 2 (see image to right). i. Change the Outfall s invert elevation to 100. j. Select Add Conveyance Link ( ) k. Pick the new Junction and then the Storage Node l. Right-click and choose Select m. Double-click on the new conveyance link i. For Inlet Invert Elevation pick the Match Inlet Junction Elevation button ( ). ii. Outlet Invert Elevation: iii. Change the Shape to Direct ( ) TIP: You won t be able to change the invert elevation after changing the shape to direct which is fine, but won t look very good on a Profile Plot. iv. Close the Conveyance Links dialog box 5. Lastly the model needs an outlet from the storage node. We ll add a weir, but you could also add pipe(s), orifice(s) or a combination of multiple outlets. a. Select the Add Weir button ( ) b. Pick the Storage Node and then the Outfall c. Press <Esc> to end the command d. Double-click on the Weir (notice that weir s are represented by links not nodes) e. Select the following properties: 27

28 f. Close the Weir dialog box 6. Change the Hydrology method to the Modified Rational Method: a. Input > Project Options b. Change the following: i. Hydrology method: Modified Rational ii. Modified rational storm duration: 100 min 7. Perform Analysis ( ) 8. Double-click the Storage Node and view the Max water elevation of the pond. 9. The pond is slightly over-designed (but we only ran the 2-year storm). BONUS: IF time allows explore a larger storm event and make necessary changes to the design a. Analysis > Analysis Options > Storm Selection b. Change the Use return period (i.e. to 10, 25, 100) 10. To add additional outlets to the Storage Node: a. You ll need to connect them with a Junction prior to the Outfall b. You ll want to draw the outlets so that they don t fall right on top of each other (otherwise you won t be able to easily pick them). Additional Information: Product Overview: Autodesk Stormwater and Wastewater Solutions Autodesk Discussion Groups: AutoCAD Civil 3D - Stormwater BIM on the Rocks: Autodesk Storm and Sanitary Analysis Learning Resources ~ Thank you for attending! ~ 28