Abstract: Employee #1 and six other employees were relining a 30-inch sewer pipe with a Rotoloc Machine. Rotoloc, a system which relines exiting pipelines, is designed so that new pipe walls are rotated into the system using the existing pipe as a host for the new material. The employees were working on sewer manholes identified as MH 33-2-2-25 and MH 33-2-2-32. The two manholes were connected with a 30-inch sewer pipeline approximately 404 feet long. After the initial air monitoring, two employees entered each of the manholes. Employee #1 and another employee entered the upstream manhole and two other employees entered the downstream manhole. Employee #1 crawled approximately 75 to 100 feet into the 30-inch sewer line while the other employee entered at approximately 150 feet to operate the Rotoloc Machine. Immediately after their entry, a noxious odor became prevalent due to a discharge from the lateral line. The discharge may have occurred from a furniture re-finishing establishment located on the street above. The attendants signaled both employees to evacuate the space. During the evacuation, Employee #1 was overcome by the fumes and became unconscious. Employees working in the down stream manhole exited the space safely. Employee #1 was extracted and revived by fellow employees and was transported to a UCLA Medical Center for treatment of chemical burns on his back.