We purchased a redexum verti-drain several years ago. It is only a 48 inch wide machine and will penetrate 10 inches. I use the 3/4" tines. Unbelievable results, not only for drainage, but it actually lifts the ground up behind the mschine and really relieves the compaction. It takes a long time to do a field, it is slow going, especially if we have the mashine set to get the closest hole spacing. but it paid for itself in a year. it will pull rocks and boulders right out of the ground.