Abstract: At 9:10 a.m. on August 19, 2013, Employees #1 and #2, employed by CONCO, a concrete company operating as a subcontractor, were working at a construction site, a concrete building. They were on the first floor and assigned to clean a stack of plywood that had been stripped and removed from the upper floors. On column B-5, there was a stack of laminated top MDO (medium density overlay) plywood, each piece measuring 4 feet by 8 feet by 14.75 inches. The stack had been piled (long side) vertically against the column by a forklift, with Employee #2 helping to guide the load. As Employees #1 and #2 were removing one sheet of plywood from the stack, the stack fell toward them. Employee #1 tried to push Employee #2 out of the way, but neither escaped in time to avoid injury. They both fell onto the concrete slab underneath the plywood pile. Nearby workers tried to lift up the pile and failed. Single sheets had to be removed from the pile, one at a time. Emergency services were called, and the San Francisco Fire Department responded. Employee #1 was transported to Kaiser Hospital in San Francisco. He was treated and released the same day. Employee #1 subsequently returned to the hospital for further treatment for a shattered right heel, fractured toes, and a fractured ankle. He was hospitalized for 8 days and underwent two surgeries where rods and bolts were implanted into his right foot and toes. Employee #2 was transported to San Francisco General Hospital. He was treated for a bruised neck, shoulder, ribs, arm, foot, and side. He was released the same day. This incident was reported to Cal/OSHA by the San Francisco Fire Department on August 19, 2013. Cal/OSHA sent an investigator to the job site on August 19, 2013, to begin the investigation. It was determined that there were no witnesses to the incident. The foreman was on another floor of the building. Interviews were conducted with Employees #1 and #2, the project superintendent, the foreman, the field safety manager, the forklift operator, and the general contractor's management staff. It was determined that the stack of plywood had not been secured. The foreman stated that the plywood had a laminated top MDO (medium density overlay) and each sheet weighed approximately 45 pounds. The total weight of 13 pieces of plywood would have been just under 600 pounds. T8 CCR 1549(d) requires piles of plywood stacked on edge to be positively secured to prevent tipping or falling. The employer was cited one serious accident-related violation of this regulation. The employer also was cited for failure to report to Cal/OSHA Employee #1's 8-day hospital stay. The investigator observed other violations, and the employer was cited accordingly.