Avoiding an existing service

Step-by-step:

Some sites will include existing services, such as water supply systems or gas pipelines that must be avoided. Your stormwater network must go above or below these existing services.

If your pipe is to go above the existing service, the ‘minimum downstream invert’ technique that was used to set a minimum outfall level can be used. However, it is probably simpler to type in the upstream and downstream invert of a pipe, to fix its level and slope, and then the other pipes should be designed around it.

1. In the Tree View, right-click the Basic Design phase and select Duplicate Phase.
2. Right-click the duplicated phase and click Rename Phase.
3. Name it, “Existing Service”.
4. Ensure all other phases are turned OFF.
5. From the Tree View, double-click the Connections node.
   
   
6. In the Connections dialog box, for Pipe (3), make sure the Lock is set to All.
7. Lower Pipe (3) by 1 meter by manually typing in the Upstream Invert Level.
8. Lower Pipe (3) by 1 meter by manually typing in the Downstream Invert Level.
   
9. On the ribbon, Preliminary Sizing tab, Network Design panel, click Network Design Wizard.
10. Click Next twice to forward to the Design Options page.
11. Enable the option Allow Backdrops.
12. Set the Minimum Backdrop value to 0.2.
13. Set the Maximum Backdrop value to 1.5.
14. Click Finish.
    
15. Close the Network Design Report.
16. In the Tree View, right-click the Flow1 flow path and select Show Profile.

You can see how the design now drops Pipe (3) to avoid the existing services.