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Staff Accomplishments

Down and dirty

August 2006
PNNL and King County Wastewater Treatment Division prepare for the effects of dirty bomb attack If a "dirty bomb," one type of radiological dispersion device, went off in a city, the immediate effects could be very serious. What would be the secondary effects, such as radiological materials being washed down the drains and into combined sanitary sewage and storm sewer systems? What are the risks to the wastewater treatment plant workers, the facility, and its treatment processes? How could the system be monitored and recovery begin? With funding from the Department of Homeland Security and the U.S. Environmental Protection Agency Region 10, research staff from the Pacific Northwest National Laboratory joined with the King County Department of Natural Resources' Wastewater Treatment Division to conduct a risk assessment and develop an emergency response plan. King County includes Seattle, Washington, and surrounding environs. Out of sight should not be out of mind Most of us have little interest in what happens to storm water or wastewater after it descends into a sewage system. But the dispersion of radioactive material could change that. The PNNL-King County team fi rst analyzed how such systems work and whether the workers might be exposed to radiation. The team created plausible scenarios of the path that radioactive materials would take through sewers and of the likely types of radioactive materials that would be found there. There were many questions: By what routes could the materials enter the system? What sorts of radioactive materials would be most likely? How long would they be dangerous to people? Who would they be most likely to threaten -- workers, the general public, those at the end of the system, boaters, fishermen, etc.? The plan that the team created was intended to be a pattern not only for King County's response to radiological dispersion events (RDEs) but for other cities as well. "The plan is a model that cities having similar combined storm water or sewage systems can employ," said John Jaksch, PNNL project manager. Monitor, protect, and communicate The research team recognized that monitoring wastewater as it progressed through the sewers could provide vital information about its potential dangers. Identifying the radioactive materials released, including amounts and health effects, could provide responders a full picture of probable RDE consequences. The team found no equipment for such monitoring was commercially available and so recommended prototype monitors that might be developed and where they should be installed. Workers in the treatment plants would clearly be in the path of radioactive materials. Although the plants had emergency plans, the team developed a radiation protection addition to the plans to train workers in radiation safety appropriate to an RDE. Waste treatment workers normally do not have training in radiation safety, so the emergency plan had to educate workers about levels of safety and concern as well as procedures in handling radioactive materials. Because communication to responders, the media, and the public is critical during an emergency, the team developed a risk-communication guidance manual for King County that focuses specifi cally on the dangers to wastewater following an RDE. The guidance provided the factual information and recommended messages and background documentation that public information officers need to communicate accurately and helpfully about incidents. A vulnerability analysis was undertaken of one of King County's main sewer and stormwater interceptors and its receiving wastewater treatment plant. The focus was finding potential vulnerable security points in the combined system and recommending security system upgrades to protect the identified vulnerabilities. Future activities In summary, the PNNL and King County team developed a range of assessments, recommendations, and guidance for determining and dealing with radiological and toxic threats to combined storm and sewage systems. The efforts resulted in assessments of vulnerability, radiological risk, and monitoring needs, recommendations about radiation protection and emergency response, and guidance on emergency communication. The team is now developing a generic version of the multi-level response plan that will be in demand for other urban areas. "The goal is to make it available to other cities and to further develop the concepts and solve some of the problems that surfaced while doing the response plan for King County," said Jaksch. For more information, contact Environment, Safety and Health Product Line Manager Kelvin Soldat

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