This morning as I was getting ready for work, I peeked out the window to see a small pile of wood which I assumed Tundra pulled from my pile to play with. Turned out it was siding off my house which he had ripped off. At this point he had become obsessed with ripping it off to the point I had to bring him inside. He is normally pretty good although he does tear up his dog bed and has chewed the picnic table. He seems to get stuck on one object for a few days and then forget and move on. My question is will he grow out of this phase. He is about 2.5 years old now. He gets plenty if exercise, we just finished a 4 mile run when this occurred

Does he get any mental stimulation? Like a training session (even if its just going back over basic commands) or a toy that's mentally stimulating (like those toys that they have to move to get treats out of.) Because he could be physically tired but not mentally and from what I've been reading its the lack of mental stimulation that causes a lot of chewing...

Was he outside alone? He could have been anxious or bored. Like Roxy mentioned, playing some games that will make them think and problem solve will really help. Remember that they are a working breed, yes they run, but they also need the mental stimulation to feel satisfied.