The following is an example scenario of a classic emergency.
At a chemical manufacturing facility, chlorine is used to bleach dye from wastewater before discharging the water into a sewer. The chlorine is stored as a liquid in a pressurized, 30-ton capacity aboveground storage tank. At 4:30 a.m., Saturday, a control valve on the tank fails and liquid chlorine is released at a rate of about 200 pounds per hour (the reporting requirement for chlorine is 10 pounds). The pool of chlorine quickly vaporizes, resulting in a toxic cloud of chlorine gas drifting toward nearby residents.
The night supervisor discovers the release at 4:40 a.m. and dials 911 to summon the local police and fire department. The supervisor then calls the National Response Center, state emergency response commission, and local emergency planning committee to report the release, as specified in the facility's response plan. Within seconds, the National Response Center relays the information to the predesignated EPA On-Scene Coordinator (OSC).
4:48 a.m.: The police and fire department arrive at the facility. After surveying the scene, the fire department calls in its hazardous materials team for assistance. The EPA OSC, en route to the site, telephones the fire department for details on the spill. About 100 pounds of chlorine have already been released and several local residents are indicating respiratory problems. The local responders begin a dual response: repairing the valve and evacuating the area.
6:30 a.m: The OSC arrives at the site. The local responders are unable to repair the valve and after conferring with the police and finding that evacuation is proceeding slowly, the OSC determines that the release is beyond the capacity and resources of the local responders, and that federal assistance is needed.
6:45 a.m.: The OSC telephones the EPA Regional office to get backup response personnel and equipment. The OSC then calls the Environmental Response Team for special engineering expertise on sealing the valve and coordinates with state authorities to get National Guardsmen to assist with the evacuation.
7:45 a.m.: Chlorine response experts start to arrive on site.
7:59 a.m.: They successfully seal the valve.
8:20 a.m.: The federal responders contain the remaining liquid chlorine to prevent further evaporation.
More than 800 pounds of chlorine were released. The OSC arranges for trained medical personnel to be brought in to treat the residents for chlorine exposure. Once the area is secure, the OSC oversees site cleanup by contractors hired by the facility owners.