An employee was assisting a crew from another company in relocating a motor control center (MCC) panel with a boom truck. The boom truck flipped on its side and came to rest at approximately a 45-degree angle. The boom contacted a large tank which stopped the truck from turning completely on its side. The employees then placed the MCC panel that was being hoisted on the ground. After resting it on the ground, it shifted and fell toward the employees. The injured employee attempted to run but there was clay slurry in the area which hindered the exit path. The injured employee was struck in the left heel by the MCC panel, which resulted in a broken heel bone and a detached Achilles tendon.