Inspection Detail

Inspection: 315776138 - Andes Construction Incorporated

Inspection Information - Office: Foster City District Office

Investigation Summary

At approximately 6:00 p.m. on Wednesday, June 19, 2013, Employee #1 was one of several workers installing a new sewer line for the city of Redwood City, CA. The line was approximately 400 feet (122 meters) long and six inches (150 millimeters) in diameter. The workers were in the middle of a street. The sewer pipe line was approximately 4 feet (1.2 meters) underground and ran diagonally beneath the middle of Oakwood Street. Workers were using the "cured-in-place" technique at this work site. This technique required that a tube membrane material be inserted from a manhole and through the sewer and then retrieved through the next manhole. The first step the workers performed after preparing the materials was inversion; this process pushed the tube membrane from one end of the sewer line to the other end through the bombardment of cool water. The workers installed Enviroliners membrane material securely in place within the sewer line from one manhole to the next with cool water, flushing it for approximately one hour. Immediately afterward, they began to flush it with hot water at a temperature of up to 150 degrees Fahrenheit (66 degrees Celsius) at 5 pounds psi (34.5 kPa). The hot water reacted with the polyester, vinyl-ester and epoxy resin in the membrane. Hot water bombardment would take approximately up to three hours for the chemical composition to react and to harden this membrane into a hard and durable pipe material in order to maintain a constant wall thickness of a pipe. It was done to create a durable, continuous, and smooth interior to promote and improve strength of the 6-inch 150-millimeter) diameter sewer line pipe. While flushing the membrane with hot water from a steam truck, Employee #1 was adjusting the temperature controls from a truck that was right beside the manhole. The narrative did not specify whether the controls were on a second truck. The connection went from the hot water steam truck hose through a manifold, using a sleeve connector, to the membrane, and then on to the sewer line. At approximately 6:00 p.m., the membrane area near the manifold and sleeve connector burst open, and a few cups of hot water squirted out and onto Employee #1, who was standing nearby. He sustained third-degree burns to his left elbow, forearm, and left lower back. He cried out in pain and fell to the ground. His foreman, who was nearby, saw what had happened and immediately turned off the water flow from the steam truck. Employee #1 was taken to a Kaiser-Permanente facility in Redwood City and then to St. Francis Hospital, where he received treatment for his injuries. Employee #1 was hospitalized over 24 hours. The employer reported the incident to the Division the next day. The Division opened an inspection fourteen days later, on July 3, 2013. At the time of this inspection, the foreman and other employees stated that what had transpired was a typical day on the job except for the membrane's bursting, which had never happened before. The foreman stated that the membrane's bursting at low pressure was an anomaly and probably due to a factory defect. The foreman stated that the membrane burst at its seams, because it was defective. At the time of the inspection, the membrane that had burst had already been thrown away. No accident-related violation was issued.

Keywords: BURN, SEWER, FOREARM, HOSE, BACK, ELBOW, MECH MALFUNCTION, HOT WATER