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Autodesk Storm and Sanitary Analysis

Free And Fast Hydrology Design


Autodesk Storm and Sanitary Analysis
Image Courtesy of Autodesk

Autodesk Storm and Sanitary Analysis (SSA) is a designer’s CAD package. It’s not meant for your everyday drafter, even designer’s might have some trouble with the bulk of this software. This is really a package for civil engineers doing primarily gravity flow hydraulic designs. The beauty of it is that it fully integrates into Civil 3D and engineers can take the pipe and surface models that designers have put together in that package and use it as a basis for their hydrological design with a single click of the mouse. Once the design is done is SSA, it can easily be imported back into Civil 3D where all the design components are automatically updated to reflect the hydrology requirements.

How It Works:

SSA runs in one of two ways: as a standalone program using schematic layouts, or in conjunction with Civil 3D. Even when you run it in standalone mode, you have the ability to insert your site plan drawing as an underlay (similar to an Xref) that you can use to help locate your design elements at real world locations and lengths.

You begin in SSA by placing “nodes” on your plan. Nodes are the physical structures that are needed within any storm or sanitary design. Storm inlets, manholes, junctions, weirs, etc. are all nodes within the program, you place them in their real world locations and they are the start point of your design. Next, you need to connect your nodes so that water can flow between them. This is done using the “Add Conveyance Link” option. What is a “conveyance?” Well, for the most part it’s a pipe, but not always. SSA also allows you to place culverts, ditches, channels, and a number of other conveyance features between your nodes through a simple drop down interface. Just click the Conveyance Link button and the dialog that comes up lets you pick what type --and shape-- of connection you need. SSA also allows you to define detention ponds, sub-basins, catchment areas and process all those portions of your network based on various rainfall demands.

Analysis Options

SSA allows you to modify each individual component (conveyance and node) manually but its true strength lies in the ability to do full analysis of your pipe network. SSA makes recommendations for sizing, based on input parameters for the storm type and region you’re working with. It takes into account the shape of your structures, sizes of your inlets, even the material your pipes are made out of, and calculates how quickly water will move through your system to the discharge point. If the expected rainfall exceeds the system’s capacity, SSA will show you where you will have backup and flooding issues and recommend size changes for your components to alleviate those problems.

SSA comes with several industry standard analysis options built into the system, such as TR-55, Rational, SWMM, and HEC-1. It also allows the use of various fluid input and calculation methods such as rain gauges and IDF or Stage Storage Curves that allow the engineer to look at different criteria based on the needs of the project or the applicable code set. This program will also generate Time of Concentration (TC) and Flow Paths for you for both single and multiple storm events. You can even create and save local storm tables for peak year storms for re-use on any project.

Once you’ve completed your design, you’ll need to be able to output the information, both in graphical and report form. Luckily, SSA has great tools for both. You can generate profiles of your network and even run animations that show the water flow inside your pipes and structures, or simply push the design back into Civil 3D for graphic presentation on your construction documents. The reports features in SSA are easily customizable and can be saved as templates for re-use on subsequent projects. You also have the option of outputting any of your data directly into MS Excel for doing additional editing and calculations if you need to.

Working SSA With Civil 3D

This method of working in SSA offers the designer the most powerful options for completing their design and generating reliable construction documents. Best practice seems to be to use Civil 3D to generate a surface model and grade out your site and any needed detention areas. You can then use Civil 3D’s pipes features to locate preliminary structures and pipes and to generate catchment areas for each of your inlets based upon the surface model. That data can be exported directly into SSA with a single button click. SSA takes the structures and pipes from your drawing and converts them to “nodes” and “conveyances”, using the sizes and shapes already laid out by C3D. This greatly simplifies the analysis process as the engineer won’t need to place individual components and modify their properties, he can simply begin running the analysis tools immediately.

Once the design is completed inside of SSA, it can be exported to a Hydraflow Storm Sewer(.STM) file which can be easily inserted right back into the original C3D utility plan. When the .STM file is inserted, the pipe network components on the drawing are updated with the shapes, sizes, and lengths that the engineer settled on in SSA. Even better, the labels for the entire pipe network, and each individual component, are updated on the plan to accurately reflect the final design. How’s that for a time and money saver?

Summing It Up

I’m no civil engineer. On my good days, I can claim to be a solid civil designer and that’s about it. The SSA program is a really powerful tool that I am actively switching to as my firm’s primary hydro software. It does everything we need it to and from a price standpoint, it’s going to allow us to discontinue subscription support for the licenses we carry on StormCad, SewerCad, and PondPack from Bentley Systems. Those packages are very good and we’ve used them for years but they do not directly integrate with C3D, our primary design package, and they also cost me a big chunk of change to maintain. SSA, on the other hand, costs me . . . nothing. It comes as part of my standard Civil 3D install and is included in my annual subscription.

SSA does everything my engineers want it to, integrates seamlessly with my primary design system, and costs me not one dime. That, in my book, is a no-brainer upgrade!

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