NTSB Issues Safety Recommendations on Stormwater Drainage System Assessment
The National Transportation Safety Board (NTSB) is an independent Federal agency charged by Congress with investigating transportation accidents, determining their probable cause, and making recommendations to prevent similar accidents from occurring. The recommendation below addresses the adequacy of stormwater drainage system assessment. The recommendation is derived from the NTSB’s investigation of the June 19, 2009, derailment of a Canadian National Railroad Company (CN) freight train in Cherry Valley, Illinois, and is consistent with the evidence NTSB found and the analysis performed.
Circumstances of the accident
About 8:36 p.m., central daylight time, on Friday, June 19, 2009, eastbound CN freight train U70691-18, traveling at 36 mph, derailed at a highway/rail grade crossing in Cherry Valley, Illinois. The train consisted of 2 locomotives and 114 cars, 19 of which derailed. All of the derailed cars were tank cars carrying denatured fuel ethanol, a flammable liquid. Thirteen of the derailed tank cars were breached or lost product and caught fire. At the time of the derailment, several motor vehicles were stopped on either side of the grade crossing waiting for the train to pass. As a result of the fire that erupted after the derailment, a passenger in one of the stopped cars was fatally injured, two passengers in the same car received serious injuries, and five occupants of other cars waiting at the highway-rail crossing were injured. Two responding firefighters also sustained minor injuries. The release of ethanol and the resulting fire prompted a mandatory evacuation of about 600 residences within a 1/2-mile radius of the accident site. Monetary damages were estimated to total $7.9 million.
The NTSB determined that the probable cause of the accident was the washout of the track structure that was discovered about 1 hour before the train’s arrival, and the CN’s failure, because of the inadequacy of its emergency communication procedurese, to notify the train crew of the known washout in time to stop the train. Contributing to the accident was the CN’s failure to work with Winnebago County to develop a comprehensive stormwater management design to address the previous washouts in 2006 and 2007. Contributing to the severity of the accident was the CN’s failure to issue the flash flood warning to the train crew and the inadequate design of the DOT-111 tank cars, which made the cars subject to damage and catastrophic loss of hazardous materials during the derailment.
Related stormwater drainage system design issues
At the time of the accident, two drainage pipes—a 36-inch pipe under the CN tracks and a 24-inch pipe under Mulford Road—were in place to handle runoff that collected in the area bounded by the UP tracks to the north, the CN tracks to the south, and Mulford Road to the east. According to representatives of the CN and the Winnebago County Highway Department, neither of these pipes was intended to be a primary conveyance for water. Instead, each was to be a relief pipe to provide an escape route once the water level in the swale area bounded by the road and tracks rose to the height of the pipes. On the day of the accident, the water level did rise to the height of the pipes, but the pipes were unable to accommodate the excess water, which allowed the water to back up and overflow the track and the road.
This was not the first time excess water had affected the integrity of the CN tracks at this location. Twice in the previous 3 years, water in the swale area had risen to a level sufficient to remove support from underneath the tracks. In 2006, water rushing across Mulford Road removed ballast from track on both sides of the crossing. Less than a year later, in 2007, water caused a washout area 5 to 6 feet long and about 4 feet deep under the tracks about 40 feet west of the grade crossing. The NTSB concluded that the stormwater drainage system in place in the area of the accident was inadequate as evidenced by the washout of the CN tracks on the day of the accident and by previous water damage to the track structure that occurred in 2006 and 2007.
It was in response to the 2007 washout that the CN installed the 36-inch relief pipe. The CN did not attempt to determine why the water had been able to rise to the level that a relief pipe was needed or attempt to evaluate the existing drainage system in light of two water incidents in less than one year, which had threatened the integrity of its tracks.
The Winnebago County Highway Department did not take any action in response to the two high water incidents because Mulford Road had not been directly affected. Highway department involvement was limited to observing the installation of the 36-inch pipe to make sure the roadway was not damaged. County officials did not consult with the CN about the sizing of the pipe, nor did the CN and the county attempt to work together to identify the reason for the unexpectedly high water levels.
The NTSB concluded that this accident demonstrates that stormwater issues can affect more than one entity—in this case, the CN and Winnebago County—and can require multiple entities to work jointly in a collaborative effort to solve any underlying defects or inadequacies. The NTSB, therefore, has issued the following safety recommendations to the U.S. Department of Transportation:
Develop a comprehensive stormwater drainage assessment program to be conducted jointly by railroads and public entities that ensures the adequate flow of water under both railroad and highway facilities, and require railroads and public entities to coordinate any changes to stormwater drainage systems before their implementation. (R-12-1)
Notify railroads and public entities about the circumstances of this accident and the importance of exchanging information related to stormwater drainage system design issues that may adversely affect the adequate flow of water under both railroad and highway facilities. (R-12-2)
Full report and Safety Recommendation R-12-10
APWA Water and Sewers resources
APWA Water Resources Management Technical Committee