NTSB Safety Recommendation Letter P-82-048 through P-82-051

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. 1 s ~ " ~ ~ : December 10, 1982 Mr. Kenneth R. Hammons City Manager City of Dublin P.O. Box 690 Dublin, Georgia 31021 SAFETY RECOMMENDAT ION ( S ) P-82-48 through -51 At 1050 a.m., e.d.t., on September 7, 1982, natural gas, blowing at 15 psig from the open ends of a 2 1/4-inch cast-iron gas main located in a deep, narrow excavation at the intersection of Cooper and Marshal Streets in Dublin, Georgia, was ignited by an unknown source. Three City of Dublin gas department employees who were working in the excavation were critically burned. The acting superintendent of the gas department, who was standing at the edge of the excavation, helped the injured out of the ditch and was seriously burned in the process. On September 7, 1982, a private contractor working for the city was installing an 18-inch concrete drain pipe under and across Cooper Street at its intersection with Marshal Street. The contractor requested that a section of 6-inch plastic water line and a section of 2 1/4-inch cast-iron gas main under Cooper Street be lowered since the drain pipe was to be installed at the depth at which these two facilities were currently located. To lower the gas main in this area, the gas department decided to cut out an 11-foot section of the pipe, deepen the excavation 2 feet, and install a 16-foot-long piece of 1 1/4-inch plastic pipe with an adapter at each end as a temporary gas line to pass below the 18-inch concrete drain. The excavation would then be partially filled so that the 18-inch concrete drain could be installed 3 feet above the temporary gas line. At 8:15 a.m., the gas department's crew unloaded a backhoe at the site and proceeded to expose the gas main. The crew then deepened the excavation an additional 2 feet below the gas main for the installation of the temporary connection. The gas main was then cleaned to prepare it for cutting and removing the It-foot section of pipe. Gas department trucks were parked in the street intersection and around the excavation site to act as a traffic barrier; however, the area was not cordoned off nor were any warning signs posted. Portable,hand-held, dry chemical fire extinguishers were on the trucks but were not readily accessible at the edge of the excavation. No air breathing equipment was on hand nor were any safety belts and ropes readily available for the emergency retrieval of persons from the excavation. 3628#

Page 2-2- When the two workers had finished cleaning the pipe, the acting superintenden the foreman asked them if they wanted the gas main isolated by valve closure and purged so that the main could be cut without being under pressure. The t elected to cut the gas main under 15 psig; they had done this several times in the rec past without incident. Valve books showing the location of all the isolation valves in system were in the trucks but were not used at this time. A review of the valve bo after the accident showed that closing three valves, one within 2 feet of the excavatio and the other two one block away from the excavation, would have isolated the involve section and would have cut off service to only one customer. A t 10:45 a.m., using a three-wheeled,hand operated pipe cutter, the two w completed the first cut on the gas main at the south end of the excavation. The workers quickly shifted the pipe cutter to the north end of the excavation and cut t h e pipe there. Gas was escaping under pressure, but the cut section of pipe remained in position because it was in compression. Another worker, standing at the edge of the excavation, jumped on the cut section and it fell to the bottom of the ditch. Blowing gas, dust, and debris then filled the ditch. The two other workers in the ditch quickly attempted to connect the plastic replacement section to the gas main using pre-positioned clamps at the open gas main. The workers first attached the replacement section to the north en of the gas main and began tightening t h e bolts on the clamp. A t 10:50 a.m., as th workers were positioning the other end of the pipe to the gas main, t h e gas ignited and fire burned from both ends of the open gas main. The three workers in the ditch, thei clothes on fire, crawled out of the ditch or were helped out by the acting superintendent. The foreman, who was then across the street, ran back to the site and radioed the city fire department and requested ambulances and assistance. department arrived at 1054 a.m. and was followed by the police de ambulance a t 1 0 5 6 a.m. The four injured workers were taken to the lo examination. Three of the workers were listed in critical condition and were transporte by helicopter to a burn treatment center in Augusta, Georgia. The acting was hospitalized locally in serious condition. Fire continued at the accident site with flames 18 feet high acr excavation. The foreman and a former gas department superintendent, who had bee summoned because he was familiar with the gas system and because they now lacke experienced help, arrived with the police and proceeded to close valves to shut off the gas still fueling the fire. The valve located within 2 feet of the north end of the excavation which was one of the three valves which could have been closed to isolate the area initially could not be reached because of the intense heat and flame. The foreman and former superintendent, therefore, closed the second line of six valves located in a two block area around the accident site. The closure of the six valves affected only seven customers; four of the customers used gas only for heating, and their fur for the summer. Although the precise time of closure was not noted, all valves wer closed within 10 minutes and the fire burned out about 11:30 a.m. Later, relightin procedures were initiated and all customer services were restored by 7 p.m; t h e 2 1/4-inch gas main was isolated within one block and no customers were affected by isolation. The Safety Board is concerned that the practice of cutting gas mains under in other than emergency conditions, involves undue risks and that the department failed to follow required safety practices. Therefore, t Transportation Safety Board recommends that the City of Dublin gas departrn#

Page 3-3- Review its operating and maintenance procedures and, if necessary, initiate changes to discontinue any practices involving cutting gas mains while under pressure except in the case of an emergency when required for public safety. (Class I, Urgent Action) (P-82-48) Review its training procedures and modify them as necessary so that all supervisors and employees are recurrently made fully aware of the correct procedures to be followed in cutting gas lines. (Class I, Urgent Action) (P-82-49) Have air breathing equipment, safety belts and ropes, and operable fire extinguishers readily accessible at the work site before beginning any operations in which escaping gas may pose a safety hazard to the public or to employees. (Class I, IJrgent Action) (P-82-50) Cordon off work sites during maintenance and/or construction activities and, through the placement of warning signs, alert the public about the potentially hazardous conditions. (Class I, Urgent Action) (P-82-51) The National Transportation Safety Board is an independent Federal agency with the statutory responsibility !I. . .to promote transportation safety by conducting independent accident investigations and by formulating safety improvement recommendations." (P.L. 93-633). The Safety Board is vitally interested in any actions taken as a result of its safety recommendations. Therefore, we would appreciate a response from you regarding action taken or contemplated with respect to the recommendations in this letter. BIJRNETT, Chairman, GOLDMAN, Vice Chairman, McADAMS, BIJRSLEY, and ENGEN, Members, concurred in these recommendations. Chairman#