Abstract: At approximately 2:15 p.m. on March 11, 2013, Employee #1, a construction laborer employed by A.R. Pipeline, Inc., was working as part of a six-person crew laying pipe across a road in Agoura Hills, CA. Employee #1 and Coworker #1 were assigned to dig by hand around gas lines in an approximately 4-foot to 5-foot deep excavation. The west side of the excavation caved in. A large piece of slurry struck Employee #1. Coworkers #2 and #3 came and pulled Employee #1 out of the trench. A call was placed to 911. Because Employee #1 was having difficulty breathing, an ambulance transported him to a park, from where he was airlifted to the Ronald Reagan UCLA Medical Center. He was admitted and treated for injuries that included multiple rib fractures to his left and right sides, a left scapular fracture, a left pneumothorax contusion, and multiple pulmonary contusions. He required hospitalization for 11 days. The Los Angeles Fire Department notified Cal/OSHA of this event at 3:34 p.m. on March 11, 2013. Cal/OSHA's Van Nuys Office initiated an inspection at 4:35 p.m. on March 11, 2013. Interviews were conducted with Employee #1's coworkers and supervisors. The investigation determined that A. R. Pipeline, Inc. is a general contractor specializing in pipeline work. The company employs between 20 and 25 employees. Based on its investigation, Cal/OSHA issued a Serious Accident Related citation for CCR, Title 8, 1541.1(a); a Serious citation for CCR, Title 8, 1541(k)(1); General citations for 1509(a), 1509(c), 1512(b), 1512(c), 1524(a)(1), 1524(a)(2), 1527(a), and 3395(f)(3); and a Regulatory citation for CCR, Title 8, 14300.29(a).