Hole in yard
Groundhogs are excellent burrowers, using burrows for sleeping, rearing young, and hibernating. The average groundhog has been estimated to move approximately 35 cu ft. or 5,500 lb of soil when digging a burrow. Though groundhogs are the most solitary of the marmots, several individuals may occupy the same burrow. Groundhog burrows usually have two to five entrances, providing groundhogs their primary means of escape from predators. Burrows are particularly large, with up to 46 ft of tunnels buried up to 5 ft underground, and can undermine building foundations, not to mention pose a fall risk to a person. It's important to find all the holes, as closing just one by filling it in won't eliminate the critter from your lawn.
The burrow is used for safety, retreat in bad weather, hibernating, sleeping, love nest, and nursery. In addition to the nest, there is an excrement chamber. The nest chamber may be about twenty inches to three feet below ground surface. It is about sixteen inches wide and fourteen inches high. There are typically two burrow openings or holes. One is the main entrance, the other a spy hole. Description of the length of the burrow often includes the side galleries of the burrow.
Groundhogs are mostly diurnal, and are often active early in the morning or late afternoon.
Probably the best way to eradicate this fellow is with a trap, or you may wish to call an exterminator. Good luck.http://www.havahart.com/groundhog-baits