An employee was hand digging a shallow trench for an electrical conduit installation. While digging the trench, the employee encountered tree roots. To remove the tree roots, he cut partially through the roots with his personal utility knife. After cutting the majority of the exposed roots, he placed the utility knife outside the trench. He then attempted to pull the remaining roots and the sudden release of the roots caused his arm to rotate backwards, allowing his left wrist to contact the utility knife blade and suffer a laceration.