This is not a trap and release method as you ask but this is how I do it. I trap them with a 220 conibear trap. I set the trap, then pin it flat with sticks over the hole. Make sure you put a big wash tub or trash can over the hole to keep out pets. Just make sure the cover is secure so nothing gets into the trap but the groundhog. Check it a couple times a day. Ive disposed of many this way. h.h.