A company live trapped the groundhog, but what does one do about the hole so it isn't re-inhabited? I've seen discussions about filling with used cat litter, concrete slurry, poly urethane, mud jacking, but nothing from a more reputable site than bloggers. The floor doesn't seem to have structural damage, but preention's clearly the goal here, while protecting the environment.

My approach is to always start with the simplest and least expensive method that will get the job done. In this case, filling the hole with soil. Did the groundhog dig under a porch or part of the house?

Under screened in porch converted to a all season room, so it has the concrete floor of a screened porch, but the walls and windows of a house. I had filled the hole with dirt last year. Also sent 5# of coffee grounds down the hole, and it didn't deter anything. This year I tried used kitty litter, then dirt.

Since this is a recurring problem, you will need to do more than fill the hole. Using hardware cloth is effective (though you'll have to do some digging). eXtension has good information about how to do this: "To trench screen, (watch out for buried wires and pipes etc.) you need to have screening above ground attached to the porch wall (1/4 inch mesh will work, galvanized is better). Then go down two inches under the soil and make a 90 degree angle out away from the porch wall at least 18 inches. This way, when the chuck meets the wall, he wants to dig straight down to get under it. But when he does he is trying to dig through mesh which he is standing on. Of course you can bury the mesh deeper if you wish and make is larger as well. " Source:http://www.extension.org/pages/36976/how-do-i-get-rid-of-a-woodchuck-groundhog-that-has-taken-up-residency-under-our-shed-porch-and-slab#.VBcCfueaDIg

Be sure to call the utility company before digging. And if you have more questions about keeping groundhogs away from the sunroom, please let me know. Good luck!