New French Drains were added recently on #16 & #17. Drains are left open to the surface for maximum effectiveness. The grass will slowly grow over the gravel. I don't like to sod over drains because it adds an layer of soil and organic matter on top of the gravel, slowing the infiltration.
Free relief from French Drains is given in the Rules of Golf. It is nearest point of relief, then drop within one club length, no nearer the hole.