Dark areas in Mesh after Shape Merge

[pixel-built]

I have created a plane with several segments, brought in lines from AutoCAD and Shape Merged them on to the mesh. I am getting dark areas at some of the edges of the mesh. What is the best way to clean these up?

 

I have included a rendering showing the dark areas.

 

I have also included a screen capture so you can see the mesh.

[Corey Beaulieu]

This usually comes from smoothing issues. If you place an edit poly on the object and then select all faces and clear smoothing groups. I'm sure this can be done with meshes too, I just never use edit mesh.