A year ago we lost a tree in a bad wind storm. After the tree and stump were removed, the contractor laid sod over the area where the tree fell. I watered it and it's growing great. My only problem is that it's squishy. Even when it's dry, it feels like I'm walking on a sponge. That area is also nearly impossible to mow, even on the highest setting. Any ideas on how to fix this? Should I start from scratch?