In the following video we show how to use the Linestring Editor and Slope Designer Tools to create a Water Diversion Berm to provide flow of 5% along the length of the berm.
You can also use a combination of the Planar Surface and Surface Intersection Linestring Command to achieve similar results depending on the shape of the berm, however with that approach, if the berm has changes in direction, you can create situations where the berm is at 45 degrees to the plane axes which will create a flat spot in the resulting berm which would pool water of course, so multiple sections may need to be modeled using different planes to avoid that circumstance.
Here is a third way that you can use to generate the swale berm line at 5% across the surface - this one uses contours on the existing surface across which you want to design the swale line. If you contour at e.g. 2’ intervals and then use the coordinate scroll to show Azimuth and distance - you can draw a line across the surface by selecting a start point and then digitizing a point where the Distance from prior point is ~40’ and the 40’ distance crosses the next contour down in sequence (a 40’ distance over 2’ drop is 5% grade).
In the following video we show how you can use the Digitize Linestring command using the circle filter option to streamline the above manual process a little more