Sewer Master Planning with AutoCAD Map 3D and Autodesk Storm and Sanitary Analysis Extension

Transcription

1 Sewer Master Planning with AutoCAD Map 3D and Autodesk Storm and Sanitary Analysis Extension Dan Leighton DL Consulting UT220-1 With the acquisition of BOSS StormNET software, Autodesk now provides the tools to perform advanced system-wide water resources analysis. In this class, you will learn how to use AutoCAD Map 3D and the Autodesk Storm and Sanitary Analysis Extension to perform city or region-wide sewer master planning. You will learn about developing the network model, using zip-code-based population forecasts to estimate wastewater inflows, performing analysis runs, displaying results, and calculating investment costs. The focus will be on leveraging Autodesk software tools to save time and facilitate analyzing design alternatives. About the Speaker: Dan has spent over 30 years doing CAD, GIS, and analysis work. For many years Dan was a consulting environmental engineer, doing advanced system modeling and master planning projects. He has also served in various roles as a product manager and director in the CAD, GIS, and database industries. For the past four years, Dan has been providing customized consulting, training, and implementation services to organizations using a variety of Autodesk products including AutoCAD, AutoCAD Map 3D, Autodesk Vault Workgroup, Autodesk Storm and Sanitary Analysis, and Autodesk Utility Design. dan.leighton@dl-consulting.net

2 Introduction In recent years, Autodesk has made strategic investments in software tools for water resource engineering. The first of these added the Hydraflow Express Extensions for AutoCAD Civil 3D. In August 2009 Autodesk acquired assets from BOSS International including their StormNET product. This has now been released as Autodesk Storm and Sanitary Analysis, and is available to subscription customers using AutoCAD Civil 3D or AutoCAD Map 3D. Autodesk Storm and Sanitary Analysis Stand-Alone 2011 Extension is a comprehensive, hydrodynamic hydrology and hydraulic analysis application for planning and designing urban drainage systems, storm sewers including highway drainage systems, and sanitary sewers. Much of the information available to date from Autodesk has covered how Autodesk Storm and Sanitary Analysis can be used for stormwater analysis and modeling -- particularly in conjunction with AutoCAD Civil 3D. Yet there are features in the product that allow it to be an effective tool for sanitary sewer analysis. In combination with AutoCAD Map 3D, you have all the tools required to perform advanced sewer master planning studies. Anatomy of a Sewer Master Plan Before we look at the software, let's start with a high level view of sewer master planning, and the steps required to complete a basic master plan. The goal of sewer master planning is to determine where investment must be made years or decades into the future to ensure that wastewater collection system can handle future growth. In particular, it aims to put a capital improvement plan in place to ensure that the investment in extension and rehabilitation projects is prudent, and that facilities are sized appropriate to future loads. Master planning therefore combines several disciplines: Wastewater flow estimation based on forecast population growth. Hydraulic analysis of the wastewater collection network. Planning to stage investment over the long term. Financial analysis of investment alternatives. In addition to the above disciplines, it is valuable to look at the steps within the typical workflow, which is shown in Figure 1. 2

3 Figure 1 - Typical Master Plan Workflow The remainder of this paper will be focused on this workflow, and how it can be accomplished primarily using Autodesk tools. Note in each of these workflow steps, we'll start with an overview of each step, and then look at how that might be accomplished using the available tools. We will focus mainly on the first four steps, as they are the ones where Map 3D and Autodesk Storm and Sanitary analysis mainly apply. Creating the sanitary sewer network Overview of this step Within this step, we'll need to work with two related source data files for pipes and manholes, get the data into Map 3D and clean it up. Here are the main steps involved: In the end, we need to create two related data files: A pipe file that describes each wastewater pipe and the pipe's characteristics. A manhole file that describes each manhole. 3

4 This data has to be in a form compatible with Autodesk Storm and Sanitary Analysis in order to use that software for the flow analysis. In our example, we'll use the ESRI Shapefile (SHP) file format to load both of these data types. Figure 2 shows the data typically required for a modeling study with respect to the pipes and manholes. Figure 2 - Required pipe and manhole data Data sources It is rare today that this information needs to be created from scratch. Virtually every city or district large enough to require master planning will have a digital version of their wastewater collection system. That said, the data required for the analysis may be in incomplete, and it will certainly require some cleanup. For our case study, we'll use two data sources. The graphical data was being maintained using MapGuide Enterprise in Autodesk's SDF format. Associated with each SDF file is a database file that was dumped in made available in comma-delimited format. The source manhole dataset has manhole IDs and most of the other information required (diameter, invert elevations, surface elevation, etc.) is available within the source pipe dataset. Using Map 3D to preparing the network model Given the source dataset as described, the following steps were taken to prepare the network mode. Note that while it's beyond the scope of this paper to describe in full detail how to use Map 3D for data cleanup, the basic steps are included. Import into Map 3D First, we'll import the data. Note that to be able to clean up the source pipe network data, it should be imported into Map 3D as AutoCAD drawing objects (as opposed to geographic data). This will allow you to use AutoCAD and Map 3D functions to clean up the source data sets. Here are the steps to follow: 1. Identify the coordinate system of the source data 2. Create a new drawing in Map 3D. 4

5 3. Set the coordinate system to match the source data using the ADESETCRDSYS function. 4. Import each SDF file into Map 3D in turn by using the MAPIMPORT function. Because this is SDF data, there are attributes associated with each file, you can access them as follows (see Figure 3 for images of the dialog boxes): In the first Import dialog box, you can click within the Data field (which shows <none>) to bring up the second Attribute data dialog box. In the Attribute Data dialog box, select "Create object data" and choose the object data table to use. Then click on the Select Fields... button. This brings up the Object Data Mapping button, which will map the available fields in the SDF file to the AutoCAD Object data fields. Now keep clicking OK until the import occurs. Figure 3 - Importing SDF content Clean up data using Map 3D editing and analysis functions Map 3D includes a variety of functions to review and cleanup network data such as the wastewater pipes and manholes. This process will vary for any given data source. For the case study, we will start with the Map 3D's Topology function to ensure that pipes and manholes are indeed connected graphically. 1. Select the MAPTOPOCREATE function, and use it to create a network topology named SEWER as shown in Figure 4. 5

6 Define network topology named SEWER Select the link objects (pipes) Select the node objects (manholes) Don't create new nodes! Figure 4 - Creating a topology 2. Now you can perform a flood trace on the sewer network to check connectivity by running the MAPANTOPONET command. This is sketched out in Figure 5. Select the SEWER topology Perform a "Flood Trace" Select the point in the network to start the trace Set direction Set highlighting Figure 5 - Performing a flood trace 3. When you perform the network trace, you'll be able to check pipe flow direction as well as connectivity. For example, in the image shown in Figure 6, it is clear that the highlighted pipes are a separate network, not connected to the rest of the system. (Note in the actual 6

7 system, there is a lift station located at the "X" that pumps wastewater through a force main to an adjacent system). Figure 6 - Example flood trace 4. Now using Map 3D editing commands, you can perform several functions to clean up this network, for example: Move, add, or delete pipes and manholes to correct connectivity issues Reverse pipe directions to ensure that all flows are downstream Creating ESRI Shapefiles The easiest way to prepare data for loading use in Autodesk Storm and Sanitary Analysis is to use the SHP format. This is easy to output from Map 3D as follows: 1. With the pipes and manholes loaded in Map 3D as AutoCAD objects, select the MAPEXPORT command. Figure 7 - Exporting to the Shapefile format 2. Select SHP format in the "Files of Type" field (see Figure 7). Enter an appropriate filename. This will now bring up the Export dialog box. 7

8 3. Because a Shapefile can only contain one type of geometry, we'll start with the pipes. Select an object type of "Line". Select objects to export by selecting the layer(s) on which the pipes lie. An example is shown in Figure 8. Figure 8 - Selecting AutoCAD objects to export to Shapefile format Figure 9 - Selecting fields to export to Shapefile format 4. Click on the Data tab, click on Select Attributes, expand Object Data, and select all of the attributes that you intend to export to the SHP file. See Figure 9 for an example. 5. Click on OK to export the data. 6. Remember you'll have to do this twice -- once for the pipes and once for the manholes. Editing object data While the Map 3D network trace function can help you identify graphical connectivity problems, you'll need a different approach to address problems in the object data, that is the set of attributes associated with each pipe and manhole. This section is included after the SHP export, because in many ways these operations are easier on geographic (not AutoCAD object) data. There are many ways to accomplish this; this paper only describes two possible methods. The first approach is to take advantage of some data editing tools in Map 3D. 1. We can start by opening a new drawing in Map 3D, and again setting the coordinate system appropriate to the SHP file created earlier using the ADESETCRDSYS command. 2. Now we can link to the Shapefile source files. You can select on the Data icon at the top of the Map 3D task pane and open the Data Connect palette. 3. Select a SHP connection, define the connection name to be PIPE (if you're bringing in the pipes first), and locate the source SHP file with the pipe information. See Figure 10 for an example. 8

9 Figure 10 - Connecting to the Pipe SHP file 4. This brings you to the screen shown in Figure 11, where you can select the connection and click Add to Map. Figure 11 - Adding the pipe file to the map 5. Now that the data is available, you will see it visible within the Map Explorer window. You can expand it to find the pipe data itself, then highlight the lowest level entry on the pipe (in the figure this is SS-Pipe3). 9

10 Figure 12 - Creating a table view of the SHP file data 6. Now click on the Table Icon (see Figure 12), and a data table will appear as shown in Figure 13). 7. In the "Data" field at the upper left of the data table, you can expand the layers option and select the pipe. When this is done, you now are in editing mode and can do several things: Make changes to data in the table Select rows and see them highlighted on the map display Add calculated columns 8. To make changes to the table, select one or more rows to edit in the table. Then check out the geometric objects using the MAPCHECKOUT command. The objects will highlight on the screen, and a pencil mark will appear on each row in the table as shown in Figure 13. Figure 13 - Rows selected and checked out for editing 9. Once rows are checked out, you can enter updated data in any of the fields. When done, you can use the MAPCHECKINALL command to check them in and commit the changes. 10

11 Finding errors using the calculate function One powerful feature here is the ability to create a calculated column of data. This is especially useful when cleaning up wastewater network data. For example, you can easily find pipes with a negative slope which (usually) means there is a data problem. 1. Near the bottom of the Data Table there is an options button. When you select this you see options as shown in Figure 14. Select the Create a Calculation... function. Figure 14 - Accessing the Create a Calculation function 2. In the calculation field, you can create a new column called SlopeChk, and a calculation that subtracts the downstream invert elevation from the upstream invert elevation, as shown in Figure 15. This creates a new column. You can then sort this column, and easily find all the pipes with negative values. Figure 15 - Simple calculation to find negative slope values 3. Once this is done, you can use the technique covered in the earlier section to edit the data associated with these pipes and correct any data errors causing the slope to be negative. 11

12 Using a spreadsheet to edit attributes While the Map 3D Data Table has some powerful editing features, you may long for your trusty spreadsheet to perform advanced editing functions. Unfortunately, Map 3D's Data Table does not support bulk paste operations. We'll use a different approach that leverages a historic feature of the ESRI Shapefile itself. While referred to as a Shapefile, there are actually several files involved. The mandatory files always found include the following:.shp - contains the feature geometry.shx - a shape index file, facilitating fast access to the geometry.dbf - a file containing the attributes associated with each shape, in dbase IV format It is the existence of this last file that makes it possible to use a spreadsheet to edit Shapefile attributes. Here are the steps to follow: 1. Open a spreadsheet. 2. Navigate to the folder containing the Shapefiles and open the.dbf file for pipes. 3. Generally the initial display will have huge column widths. Select all the columns, and change their column width as a group to a width of 20. This will at least get everything on the page so you can see what you have. 4. You may want to format numeric fields to be easier to read; by default they come into the spreadsheet showing 16 decimal places. 5. You can now make changes directly to the data in the Shapefile. However, read the notes and warnings! Notes and warnings about editing the Shapefile DBF The association between records in the.shp file containing the feature geometry and in the.dbf file containing the feature attributes is implied. In other words, the first record in the.shp file is implicitly associated with the first record in the.dbf file, and so forth. This means: You can not add or delete records in the.dbf file. If there were 50 records when you started editing, there must be 50 when you are done. You can not change the sorting order of records in the.dbf file. This is because the current order of items as found in the DBF matches the order of items in the related Shapefile files. The column headers cannot be more than 10 characters in long. It is recommended that you always work on a copy of the.dbf file, so if you make a mistake you can restore the original. Note there are a number of useful things you can do to the.dbf file without causing problems. These include: Change the order of the columns (except for the last column). Change the column headers (so long as they are 10 characters or less). Change any data in the table (so long as numbers remain numbers). Add a new column (as long as it is inserted to the left of the rightmost column). You can also change the sorting order so long as you restore it before you finish. So, for example, you could start by adding a column with sequence numbers. You can then sort things differently for to achieve your goals, and then before you save the.dbf file use the sequence column to reset the content to the original order. 12

13 Defining sewersheds and load points One of the unique aspects of modeling wastewater systems is the concept of a sewershed. Many people are familiar with watersheds, which are catchment areas for rainfall that follow the natural contours of the land. Sewersheds are similar, but follow the man-made environment of the wastewater collection system. You cannot use a DTM file or some other form of contour information. The practical consequence is that there's no simple way to define sewersheds. Overview of this step The goal of this project step is to create a set of sewersheds. As follows: The resulting sewershed data will be a set of polygons as follows: A topologically correct polygon that can be overlaid with polygons containing population or load data. Information on the manhole to which the load will be applied. This information will be merged with the node file before loading it into Autodesk Storm and Sanitary Analysis. Drafting the sewersheds For this case study, we'll assume the sewersheds are hand digitized using Map 3D's AutoCAD drafting functions, working upon the Shapefile copy of the pipe and manhole network. Color pipes by diameter to better define sewersheds To make it easier to determine what should be in which sewershed, we'll theme the pipes based on diameter. In short, we can more easily identify the edges of the network because the pipes are smaller. 1. In the Task Pane, select the Data icon, click on Connect to Data..., and connect to the shape file containing pipe data. 2. Switch to the Display Manager tab. Click on the pipe layer, then click on the Style button. See Figure 16 for an example of how you might style the pipe data. Figure 16 - Example pipe styling to identify major pipes 13

14 Create a load point node When drawing sewershed boundaries, it's critical to know where your load point is positioned. To help you keep things in order, you could create a block to insert at the node where each load point will be located. A simple circle will do, with an attribute to indicate the manhole ID of the load point. Drafting the sewersheds Now you have the tools necessary to draft sewersheds in a reasonably efficient fashion, and in such a way that you can convert them into data that you can later use. The basic steps to draft these are: 1. Create a new layer for drafting the sewersheds. Set the color so it will stand out, and make the layer current. 2. Decide where the load point will be. Determine the manhole number for this point, and insert the load point block at that point with the attribute set to the manhole ID. Note if you have the pipe file available, you can click on any pipe and look at its properties to determine the downstream manhole ID; this can be a great help in determining the load point manhole ID numbers. 3. Draw lines delineating the sewershed boundaries. When intersecting another boundary, use the AutoCAD snap functions to ensure clean polygons are drawn. See Figure 17 for an example. Figure 17 - Example of drawing sewersheds Creating the sewershed data file The last step for this part of the process is to convert the lines and blocks just created into topologically correct polygons representing the sewersheds, with the manhole attribute of each load block established as the load point ID. 14

15 Define current and future loads by sewershed Overview of this step To perform the network flow analysis, we need to know the inflow into the network load points for each modeling scenario. These inflows are based on current or future population and land use, as applied to the sewersheds. The steps we'll take are as follows: Our goal for this step is to have a set of spreadsheet data with one row for each load point (manhole), and a column for each modeling scenario. An example is shown in Figure 18. Data sources There are several data sources involved: Figure 18 - Example spreadsheet with load data A map of zoning areas within this city. The original map was a PDF file (the GIS or CAD source was unavailable). A set of land use estimates in a spreadsheet by zoning area. The file with sewershed boundaries and associated load points that was created in the previous project step. 15

16 Defining zoning polygons The land use for this case study is based on zoning polygons. The actual study area is a subset of the available zoning map shown in Figure 19. Process to create polygons This image was available as a PDF file, and no scale or coordinate information was available. Map 3D proved quite handy to create useful polygons. While it is beyond the scope of this paper to present the step-by-step details of the conversion, the overall process was as follows: 4. The PDF image was converted to a.tif. 5. The.TIF image was loaded into Map 3D to serve as a background layer for digitizing. 6. Zoning boundaries were drawn as lines on the ZONING layer. 7. A block called ZONEPT was created with a single attribute called "ZoneTP". Figure 19 - Zoning map image 8. One ZONEPT block was inserted within each zoning area, and the attribute was set to the zoning type for each area. 9. The Map 3D drawing cleanup functions were used to clean up the lines that represented polygon boundaries. This included eliminating overshoots, correcting undershoots, and breaking lines where one boundary intersected or crossed another. 10. A Map 3D Topology was created based on the content of the ZONING layer, using the ZONEPT blocks as centroids. Errors located while creating this topology were fixed. 11. The zoning map was saved as a temporary file. Aligning the zoning polygons with other maps As mentioned before, the PDF file had no scale and no coordinate information, so the next step was to use Map 3D's functionality to correctly scale and align the zoning polygons. This was done as follows: 1. A DWG file with roads and property boundaries was brought into Map 3D at the correct scale and map projection. 2. The new zoning map was also brought into the same Map 3D session. The move command was used to position the zoning map near the road/property map for convenience sake. 3. The rubbersheet function was used with four alignment points to associated the zoning map (which covered a significantly larger area than the study area) to easily identify points of correspondence on the road/property map. 4. The zoning polygons and centroids were then exported in Shapefile format. This export included the topology IDs for each polygon, the area of each polygon, and the zoning type value from the centroid block. 16

17 Calculating sewershed land use allocation The calculation itself is done in two steps. First we need to perform an overlay analysis to determine how much of each sewershed polygon lies within each zoning polygon. Then we need to do some flow analysis calculations. Overlay analysis The first step is to determine how much of each sewershed polygon lies within each zoning polygon. Figure 20 will help you visualize this: Figure 20 - Zoning polygon overlay with sewersheds This analysis can be done using Map 3D's feature overlay function as follows: 1. Open a new drawing in Map 3D. 2. In the Map Explorer task pane, click on the Data icon to connect to data. 3. Connect to the zoning Shapefile and display it in Map 3D. 4. Connect to the sewershed Shapetfile and display it in Map 3D. At this point you'll have something similar to what is shown below in Figure 21. Figure 21 - Overlay of sewershed (green) polygons over zoning (yellow) polygons 5. Now we can do the overlay analysis. We start by selecting the Feature Overlay function from the Feature panel on the Analyze ribbon. This brings up the Overlay Analysis dialog box. Enter the source as the Zoning layer, and the overlay as the Sewershed layer. Then select Intersect as the analysis type. See Figure 22 for an image of this screen. 6. Click on Next. Set the output to be (for example) 17

18 SShedLoadPoly.sdf and the Layer Name for the intersection to be sometsshedloadpoly. Use the suggestion for sliver tolerance. Click on Finish to perform the analysis. Figure 22 - Setup for overlay analysis 7. A new layer will appear in the Display Manager. For the sake of this project, we'll call these the "Overlay Polygons". Calculate new areas Each of these new overlay polygons contains the area representing a single zoning area allocated to a specific single load point. To determine the amount of flow represented by this area, we need to know the area itself. This must be calculated as follows: 1. Click on one of the overlay polygons to highlight it. Then right click and select Properties to observe the properties. An example image is shown in Figure Note that the default properties include geometry type and vertices, but do not include the area of the resulting polygon! This needs to be calculated. 3. In the Display Manager window, right click on the new SShedLoadPoly layer that you created and select Create a Calculation In the Name field, enter AllocArea. Figure 23 - Overlay properties 18

19 5. In the calculation area as shown in, enter the equation "Area2D (Geometry) / This is asking to calculate the 2D area from the overlay polygon geometry, and divide this by 43,560 to convert square feet (the object's native units) to acres. Figure 24 -Calculating acres of each analysis polygon 6. Click on OK to complete the calculation. 7. Be sure that the new layer is selected within the Display Manager. Click on the Table button. A data table will appear similar to what is shown in Figure Figure 25 - Data table in Map 3D for Sewershed Load Overlay Polygons 9. This is the information we need to perform the calculation of actual wastewater loads by load point. This will be done in a spreadsheet, so the last step is to export this information 10. Right click on the tiny flag image in the upper left. Select "Select All". Then right click again and select "Export...". Name the file SShedOverlayPoly.csv. 11. Open a spreadsheet and load the file containing the overlay polygon data. 19

20 Calculating flow loads Finally we are ready to actually calculate the flow loads. Figure 26 - Calculation for flow loads As stated earlier, there are many ways to calculate flow loads for a master planning project, and this is only an example. Figure 26 provides a graphic of the calculation, although much of the detail is left out. In short, the calculation is as follows: For each zoning polygon, we know the area, and the percentage of each land use. We need to make an assumption about the contribution of each land use to wastewater flows. This assumption will be based on a table as shown in Figure 28. The flows are based both on land use and density, which is based on zoning type. Given the above, we then look at each sewershed. The SShedOverlayPoly data determines the allocation of Zoning flows to load points. For each load point, we take each overlay polygon, or in other words each corresponding entry in the SShedOverlayPoly table and calculate area the single family, multi-family, commercial, and industrial wastewater flows within each subpolygon. These values are then multiplied by the flow rate assumptions and totaled, to give us our final flows by overlay polygon. These are summed up and applied to the load point. Figure 27 shows a portion of the spreadsheet that holds the current and future land use estimates for each of the zoning polygons for the case study project. This will be combined with the areas of each overlay polygon and the flow assumptions listed in the next section for the final result. Figure 27 - Current and future land use estimates by zoning polygon 20

21 For the sake of this case study, we are using the following flow assumptions: Figure 28 - Flow rate assumptions by land use and zoning type Given these two tables, we combine them with data about the overlay polygons to create a spreadsheet that shows flow by overlay polygon, as shown below in Figure 28. Figure 29 - Flow calculation spreadsheet summary The final step is to sum up these flows by load point and then apply them to the hydraulic model. For reasons we'll go into further in the next section, we need to add these flows to the manhole data file, as described in the section that follows. Applying calculated flows to the manhole file The spreadsheet calculations described above and shown in Figure 29 have multiple lines for each load point that need to be summed. In addition, as will be described further on page 25, these flows need to be imported into Autodesk Storm and Sanitary Analysis as part of the file containing manhole information. 21

22 The last step of flow calculations is therefore to take the manhole DBF file associated with the manhole Shapefile created earlier, and add in these load values. Here are the suggested steps to follow: 1. Open the DBF file in Excel. 2. Insert three columns to the left of the rightmost column (remember as described on page 12 you can modify the DBF and add columns, but only if they are to the left of the rightmost column). Label these columns FLOW2000, FLOW2030, and FLOW Using the SUMIF function, link to the spreadsheet containing the calculated flows by overlay polygon (Figure 29). Create an entry for every manhole. Only some of them will have nonzero values, because only a small percentage of the manholes have loads. See Figure 30 for an example of the function to use. Figure 30 - Example Excel function to sum overlay polygon data Perform network flow analysis At last the actual modeling analysis is within sight! Here is the work flow that we'll follow: To begin, however, let's take a quick look at Autodesk Storm and Sanitary Analysis. Autodesk Storm and Sanitary Analysis for wastewater modeling One of the earliest uses of computers for civil engineering was to perform various types of water resources modeling analysis. Models were developed, starting in the early 1960's, most commonly using the FORTRAN language. Of course, in the "old days", the computer's job was the mathematical analysis itself. The input data consisted of text and numeric information in a rigid format. It needed to be perfect or the model would fail to run. The output consisted of a long paper report. While the models were refined over the years, by the 1980s there was little additional model development, and the models were trusted by the engineering community. How does this apply to Autodesk Storm and Sanitary Analysis, or "SSA" as it's often referred to? SSA is not, itself, an analysis model. It is a comprehensive software wrapper around several of the traditional water resources models; this wrapper makes it far easier to format and prepare the input data, and allows users to display, plot, analyze, and export the output data in a variety of fashions. This is illustrated in Figure

23 Figure 31 - Autodesk Storm and Sanitary Analysis For the sake of this case study, the key points are therefore: How do we get data into Autodesk Storm and Sanitary Analysis? How do we run the model itself? How do we take advantage of the output information? Loading data into Autodesk Storm and Sanitary Analysis For this case study, data is most easily loaded into SSA using the GIS Import function, located on the File Menu (see Figure 32). There are several types of import, but in large part these are focused on existing modeling files in other formats or LandXML data from Civil 3D. For our purposes, the GIS import works best, and it is easily exported from Map 3D. The GIS import function has three steps: Import pipe data Import junction data Input subbasin data We'll talk about each of these in turn. Figure 32 - Accessing the Import function 23

24 Importing pipe data The import function begins with pipe data import. The first thing you'll see is a dialog box as shown in Figure 33 Figure 33 - The pipe data import dialog box The steps to follow are: 1. Select the input file. Note this must be a Shapefile. 2. Select the options. In general, you should be importing an entire clean pipe network from Map 3D, so you uncheck all the options except for Recompute Pipe Lengths. 3. You now need to match attributes within the Shapefile with attributes required by SSA. For each of the SSA fields (titled "Storm Fields"), select the matching field from Map 3D in the Shapefile. At a minimum, you'll need a unique ID for each pipe, upstream and downstream inverts, a roughness coefficient, a diameter, and upstream and downstream manhole IDs. Note that length, if not available, can be computed by SSA by checking off the box mentioned in the previous step. 4. Once this is done, check the units and decimal values to be sure they are appropriate. Then click on Next. 24

25 Importing manhole data (a.k.a junctions) SSA is designed for both storm and sanitary analysis, so manholes are referred to throughout as junctions. The next dialog box you'll see is to import junctions, as shown in Figure 34. Figure 34 - The junction data import dialog box The steps to follow are: 1. Specify the filename. 2. Match the fields in the Shapefile to the "Storm Fields" listed. The required fields for wastewater analysis are Junction node ID, invert elevation, rim elevation, and dry weather flow. We'll talk a bit more about the dry weather flow value shortly, but for now know that this is where you specify the calculated flow load for the various load points. 3. Check the units and decimal values to be sure they are appropriate. In particular, be sure that the units are correct for dry weather inflow. 4. Click on Next. What about subbasins? The next dialog box to appear is for importing subbasin data. But it may come as a surprise that we will not import sewersheds as subbasins. This is because we are making two key assumptions for our analysis: First, we are assuming that the master planning analysis is for a separated sewer system, and the stormwater is entirely handled by separate conveyances. Second, we are assuming that the amount of RDII (Rainfall Dependent Infiltration and Inflow) is negligible, and that the only flows into our network are "dry weather flows", that is to say wastewater from intended house and business connections. Of course, every analysis is different, and for your master planning project you may need to consider the effects of RDII or combined sewer configurations. Know that Autodesk Storm and Sanitary Analysis, and the underlying model we will be using (in this case, EPA SWMM) can handle analysis of combined flows and RDII, but it is beyond the scope of this AU session! 25

26 Model setup Wastewater models for master planning that do not involve stormwater flows and RDII are inherently simple. Design tends to be conservative and generally there is no need to handle the complexities of diurnal flows or storm events. While these could indeed be handled by Autodesk Storm and Sanitary Analysis, they are beyond the scope of this AU session. This means that the model setup is quite simple, with the following steps: 1. First, open the Project Options (on the Input Menu). This brings up a dialog box as shown in Figure 35. Check the following settings: Units and flow units should match what your project is using. Hydrology method should not matter, but be sure it is set to EPA SWMM Hydraulic routing should be set to Steady Flow. If you have force mains, select the preferred method for analysis. Set storage node exfiltration to None. Figure 35 - Setting project options 2. Next, bring up the Analysis Options (on the Analysis Menu). The dialog box for this is shown in Figure 36. Because we are not including rainfall events or RDII, and are assuming steady state flow, the settings here are also quite simple. The specific things to consider are: You need some simulation period, even for a steady state flow analysis. An hour is sufficient. The dates don't matter because you're not modeling storms, so leave the start and end dates the same, with an hour difference. 26

27 Set hydrodynamic analysis parameters to Dampen. Ignore the Storm Selection tab -- for steady state analysis of a non-combined sewer network, you won't need any storms. Figure 36 - Setting analysis options Performing the modeling analysis Now that you've set the parameters, the analysis is almost anticlimactic, unless of course you have a problem with your network. To run the model, select the Perform Analysis option under the Analysis menu, or click on the small running man icon ( ), What to do if a run fails It is common for the first few runs to have problems and fail. If failure occurs, you'll see the dialog box shown in Figure 37. Figure 37 - Failure dialog box 27

28 For a sewer network study, the failure is almost always due to a network configuration problem. When you click on OK, a copy of the ASCII output report will appear. Near the bottom of the report, the errors appear. Some of the common errors you will encounter include: Negative slope -- a pipe's outlet is higher than the inlet Split flow - two pipes are defined leaving a manhole ID errors - a manhole or pipe ID is missing or invalid When the problem is a data error, you have two choices when a run fails. You can correct the data within Autodesk Storm and Sanitary Analysis, or you can correct it within Map 3D and reload the data. Because importing from Map 3D is simple, and because of the effort required to export the data and correctly synchronize it with the Map 3D source, the recommendation is to maintain correct data in Map 3D at all times. Autodesk Storm and Sanitary Analysis can be very useful to help find flow, data, and connectivity errors, but by making the changes in Map 3D you can ensure you have a single clean dataset for your master planning project. Model results Assuming the modeling run was successful, there are then many things you can do with the results: Create custom reports Output the traditional ASCII model output file Output data to an Excel spreadsheet Generate profile plots For the sake of master planning analysis, the logical next step would be to output the model results to an Excel spreadsheet, because this is the best tool to use to move on to the next step and identify required facility sizes for future loads. Performing multiple modeling runs Generally, a master planning study requires at least three modeling runs to analyze current, near future, and longer term scenarios. Often there are many more, with different growth scenarios or different assumptions about investment and requirements. Because there is no efficient way to import sanitary flow data separate from manholes, the recommended process to perform multiple runs is as follows: 1. Perform network cleanup within Map 3D. 2. Assign flow data for all scenarios to appropriate nodes within Map 3D. This way, all the flow data is available upon import into Autodesk Storm and Sanitary Analysis. 3. Import data for a given analysis run, specifying the particular flow scenario within the Node Import dialog box and assigning it to the Dry Weather Flow field as shown in Figure

29 Figure 38 - Importing nodes with alternative flow scenarios 4. Make any required changes to the model that cannot be imported (for example adding pumps). 5. Perform the model runs. Figure 39 shows an example of the results you might expect from two different modeling scenarios. The first is the base case for land use in the year The second is a test run with a "low" estimate of flows for the year As you can see in the second run, there are more potential problem areas, and in particular in the lower right there is an area that needs additional capacity. Figure 39 - Comparing analysis runs Identify required facility sizes for future loads With sewer master planning, the model analysis is not the end goal, but simply a means to see where the system is inadequate. While Autodesk Storm and Sanitary Analysis has powerful modeling features, it does not have the ability to recommend appropriate pipe sizes. This is work best suited for a spreadsheet. 29

30 This section will therefore cover two topics: getting results data into a spreadsheet form, and bringing results back into Map 3D for results mapping. Exporting data to a spreadsheet Autodesk Storm and Sanitary Analysis has a couple ways to output data into a spreadsheet format. The easiest way is simply to select the Excel Table Reports option as shown in Figure 40. Figure 40 - Producing Excel Reports The alternative is to use the Generate Custom Report option, which brings up the following control dialog box: Figure 41 - The Custom Report Options dialog Using this option, you can have fine control over exactly what is output. Exporting data to Map 3D The export process To better understand the model results, data can be exported to Map 3D. While there are several ways to do this, probably the best choice is to use the GIS Export option. When you select this option, you are led through several screens to determine exactly what data to output in SHP file format. 30

31 The third screen lets you select what element types to export; for this master planning study, the only one that really makes sense is to export pipes, as shown in Figure 42. Figure 42 - Selecting Pipe data for export Then, clicking on the Field Definitions tab, you can select exactly what data will be included in the SHP file. Only some fields are relevant for this study, and need be chosen, as shown in Figure 43. Figure 43 - Selecting specific pipe fields to export to SHP format Once this is done, clicking on Finish causes a shape file with the pipes and the selected parameters to be generated. Thematic mapping in Map 3D Once the export is complete, the SHP file information can be brought into Map 3D like any other type of GIS data. It can then be themed as shown in Figure 44, or you can work on the data in the table view. 31

32 Figure 44 - Themed data in Map 3D Analysis of resized pipes It is beyond the scope of this paper to cover the process of calculating appropriate replacement pipe sizes. This is probably best done in a spreadsheet environment. The pipe sizes can then be reset within Map 3D, and the model rerun as described earlier in this paper. One alternative to consider is to have multiple fields in the Map 3D pipe file for diameter values. This would allow you to more easily have multiple analysis scenarios, and much as we did for flow values in the manhole file, you could choose the set of diameter values for a particular scenario. Closing thoughts This paper and AU session has attempted to provide an overview of the most relevant ways that AutoCAD Map 3D and Autodesk Storm and Sanitary Analysis can work together for a wastewater master planning study. Here are some key points to consider: Test everything on a small system to start: The final system highlighted in this paper has nearly 3000 pipes. While both Map 3D and Autodesk Storm and Sanitary Analysis can handle systems of this size, it is faster to work things out on a subset of the system to establish the best approach and the process. 32

33 Establish a workable cleanup process: The most time consuming part of any master planning project is getting the initial data ready for analysis. This requires that you establish a process for this cleanup to know what you've done, know what remains, and avoid rework. Decide on the most efficient modeling process: For the case study shown here, the most efficient way to perform multiple runs was to load the dry weather flow data with the manhole file. If you are performing an analysis with (for example) RDII, it may be easier to load using one of the other supported formats where this data can be included in the load files. Take advantage of "Load/Save" features: Both Map 3D and Autodesk Storm and Sanitary Analysis have features that allow you to save a given import or export configuration and reuse it. This can be especially useful when exporting from Map 3D, because you'll do the same export over and over. Saving the configuration allows you to avoid errors if you are changing or renaming data parameters and selecting specific data subsets. While this paper has focused on how to leverage Autodesk's Map 3D and Storm and Sanitary Analysis products provide a powerful combination for wastewater master planning, it is important to note that ultimately, the water resources engineer responsible for the project must also bring experience and modeling strategy to bear on the project. These software tools are powerful and flexible, and can save the engineer time and money to complete a project, but they require a skilled hand to use properly and to get valid analysis results. 33