Alan Gilbert from Autodesk shows how to quickly import survey points directly into a Civil 3D Surface from a CSV text file.
I almost never employ COGO points in a Civil 3D Surface via Point Groups except in temporary builds. You are asking for trouble if you do so.
I tend to employ the Toolspace's Surface Definition and Point File method and employ .AUF files to keep things clear and separate from any original data files.
Alan's walk through shows that Civil 3D is very flexible about how you can suck in data.
You might want to check out the Quick Surfaces from Survey video too.