Design Storm Systems in Civil 3D (10:12 min)

The Storm Drainage design of any project can be the most important aspect. Engineers and designers commonly ask themselves where they will drain the site to, where a detention pond be and how large they need to make a storm drain pipe. Let’s see how Autodesk Civil 3D can help answer these questions.

Here’s how:

1. To start, we need to layout a pipe network. In Civil 3D, turn on the slope arrows of the surface by selecting the surface and selecting “Edit Surface Style” and turning on “Slope Arrows”.

2. After assessing where the water travels in your site, turn off “Slope Arrows”.

3. In the “Home” tab, in the “Create Design” panel, select “Pipe Network” and choose “Pipe Network Creation Tools”.

4. In the window that appears, do the following:

  • Name the network
  • Select the preset storm sewer parts list
  • Select the surface name
    • i. If you don't know the name of the list, select the green icon next to the “Surface name” drop-down menu and choose the surface from the screen.  
      • Turn off structure and pipe labeling for now
      • Select "OK"

5. This will bring up the “Network Layout Tools” for your storm drain system. In the left drop-down menu, you will find structures and, on the right, you’ll find the pipes.

For our example, we are selecting the following:

  • Structure: “Rectangular Structure Slab Top Circular Frame” à “15 x 15 Rect Structure”
  • Pipes: “15 inch Concrete Pipe”
  • “Pipes and Structures”

6. Now select the insertion point on the screen and continue to draw the network.

7. We want to add a manhole, so change the structure in the “Network Layout Tools” to “Concentric Cylindrical Structure NF” à “48 inch dia 24 inch cone Concentric Structure”. When you place your manhole in the network, change the structure back to “15 x 15 Rect Structure”.

8. Continue to draw the network and lead it to the pond.

9. Back to the manhole, select “Pipe and Structures” again from the “Network Layout Tools”.

10. If you hover over the manhole and pipe, you will see a few symbols.

  • This means it will connect a pipe to that structure. It’s not going to place a structure on a structure.

  • This means it will insert a structure at that point, breaking the pipe at that invert.

11. We’re going to add a pipe to the manhole. Draw the pipe and snap it to the manhole.

12. If you make a mistake and want to change a part of a pipe, select the part to swap, right-click and select “Swap Part”. From there, select the part you need for the project.

13. To change the size of a pipe, right-click on a pipe and select “Swap Part” and pick the pipe size you need. You can also go right-click and select “Pipe Properties” and manually change the diameter in the “Pipe Properties” tab.

14. Now, close “Network Layout Tools” and check out the elevations of the network. Select the starting point of the network and click on “Structure Properties”.

  • We can see our elevation in this example is about “5387.00’”.
  • We want the network to be three feet deep to the invert, so change the elevation to “5384.00’” in the “Connected Pipes” tab.

  • Select “OK”.

15. Next, select the pipe connected to that invert, right-click and select “Pipe Properties”. Here we can see the starting (5384.00’) and ending (5380.76’) elevations of the pipe.

Change the “Pipe Slope (Hold Start)” to “-1%”. Click “Apply”. This will change the starting (5384.00’) and ending (5382.20’) elevations.

16. To match elevations of pipes, simply select the invert between two pipes and go to “Structure Properties”. In the “Connected Pipes” tab, copy the elevation of one pipe and copy it to another. You can do the same for the centerlines and crowns.

17. Repeat the process for the rest of the pipes in the network.

18. When you come to the end of the network that reaches the pond, check the elevation of the pond (5382.5’) and set the headwall to match it. Click on the headwall and go to “Structure Properties” and change the elevation to “5382.5’” to outlet it into the bottom of the pond.

Now we have a storm drain system with custom elevation that drain into a pond. The next step is to analyze!