The break in a 10-inch water pipe at the Y-12 National Security Complex on a Friday night in Juneâ€”it spilled about six million gallons of water and killed several thousand small fishâ€”was discovered by a diligent engineer who had returned to the plant to check on an abnormal water tower report, officials said.
The Defense Nuclear Facilities Safety Board reported that the plant contractorâ€™s utilities and environmental compliance organizations both had had indications of an abnormal condition, but B&W Y-12 had not established a procedure to respond to the signals.
â€œThe break was discovered because a diligent system engineer decided to come back in to the site and check on an anomalous report of a low level in a water tower that had cleared as the pumps refilled the tank,â€ the DNFSB report said. â€œB&W management is evaluating ways to improve recognition of a problem from the available indications during off hours.â€
Y-12 said other engineers who monitor utilities at the plant helped as well, tracing the water level change back to the line break.
The DNFSB report said the potable water supply line, which is part of a fire suppression system, burst Friday night, June 7, east of Building 9207, which is in the old biology complex on the east end of the plant. But the rupture was not discovered until Saturday morning.
â€œThe delay in recognition can be partially attributed to the isolated location of the sub-surface break, most site personnel being gone for the weekend, and water towers being refilled,â€ the DNFSB said in a weekly report posted on its website.
The Potable Water System, or PWS, feeds all the fire suppression systems at Y-12, but the water supply was not affected by the rupture because pumps were able to maintain adequate levels in water towers, the report said. The DNFSB said a similar pipe break occurred in September 2012.
The chlorinated water that spilled into East Fork Poplar Creek after last monthâ€™s rupture killed an estimated 8,500 minnow-sized fish and almost 30 salamanders, officials said in a June 11 media advisory.
B&W Y-12, the plantâ€™s management and operating contractor, said it started â€œimmediate corrective actions to isolate the ruptured pipe and to monitor aquatic causalities.â€ Continued monitoring on Sunday the weekend of the spill showed no more creek casualties, and hundreds of healthy fish and other creek life were observed throughout the creek on both days, Y-12 said.
Fishery biologists from Oak Ridge National Laboratory estimated the mid- to long-term impact on local fish and salamander populations associated with the spill was likely to be minimal, Y-12 said.
East Fork Poplar Creek runs from Y-12 through the middle of Oak Ridge and out to west Oak Ridge near the former K-25 site, now known as East Tennessee Technology Park.