Creating a basin from User-Defined Contours

Creating a basin from User-defined Contours can be fast and easy in Civil 3D. Here are the steps you need to take in order to achieve this:
The first thing you should do is to determine the location for your basin and decide what the pond edge elevation is going to be. In this exercise I will use the surface shown below and my edge elevation will be 184.35.

Next we need to create the User-Defined Contour for the Basin Edge.
To do this: Click on your surface and then select "Surface Properties". In the Surface Properties dialog box select the "Analysis" tab. On the "Analysis Type" Properties pull down select "User-Defined Contours". In the Number of Ranges type "1" and then select the Add arrow. After the contour has been added to your Range Details click on the "Elevation" and set it to your edge value.

*Note: Make sure your surface style has the User Contours" turned ON in the Display tab.

Next select your surface and select "Extract objects" from the Surface Tools panel. In the "Extract Objects from Surface" box, deselect all items except "User Contours" and select OK. After doing this you will have an elevated polyline of your pond edge. Select the polyline and then (on the Home tab) select "Feature line" and then select "Create feature line from Object. In the Create feature Lines box select your site and style and/or press OK. You now have a feature line you can use to create your pond. Now use your grading tools to grade inward to create the pond condition to meet your needs.

**Note: Don't forget to Create the infill to create to bottom of your basin.

***One last Note: If your unsure of your basin bottom elevation but know your capacity. Select your surface and expand the Analyse panel. You will find the "Stage Storage" tool. This tool has many options to help you calculate your basin. I hope you enjoy this. Check back again soon.