Abstract: On March 26, 2007, an employee, a general manager and a coworker went to the jobsite at the new retirement home construction site to dismantle the scaffold. At approximately 9:30 a.m., the coworker was dropping a piece of a 2-inch thick, 10-inch wide, 12-ft long plank from three and half level of the scaffold at approximately 23-foot high above ground. Unexpectedly, the employee was walking toward to the direction and was hit by the plank. The plank knocked off the employee's hard hat, and hit his right shoulder. The employee was knocked down to the floor, and was seriously injured with head concussion. One of construction worker saw the accident and called La Verne Fire Department. The paramedics came to the site and took him to the County USC Hospital for medical treatment. He stayed in the hospital for three days, and was treated for broken bone on his left shoulder and a fracture on his left ankle.