During our aerification this year we're doing a Drill and Fill on our old greens(#1-5,7,9,10)as can be seen here on #10.  The Drill and Fill process helps get more sand down into the soil profile which will help the greens drain better. The benefit to you the golfer will be firmer/faster greens similar to our newer greens. In the middle picture drills drill holes into the greens and then in the bottom picture tubes next to the drills fill the holes with sand.