For this exercise we will be adding a Rain Garden, Filter, and Pond as a treatment train. It should be noted that the rain garden is modeled as a lumped LID to avoid having too many commands in the model. This is done by adding up the storage in all the rain gardens in the subdivision and modeling them as a large rain garden. Although the resulting large rain garden is unrealistic in size, it is an acceptable way to build a model for planning purposes.
In Project Manager, navigate to the scenario you wish to duplicate, i.e. “Post-Dev. Initial” model in this exercise, and duplicate the scenario by either of the following two ways: 1) click the Duplicate button 
at the top; 2) right click the selected scenario to open context menu and select Duplicate.
The Duplicate Scenario window will pop up. Include Commands and Runs in the Duplicate Scenario window and change the name as “Post-Dev. Working”.
To add LIDs to the model simply drag and drop the LID command to the appropriate places on the canvas. Add or delete links when necessary. Your model should look like this:
