20061110/密西沙加1979大疏散(书摘)

The following is an excerpt from Tresspass Against Us:? Dow Chemical & the Toxic Century by Jack Doyle.? Published by Common Courage Press, Monroe, Maine, 2004, www.commoncourage.com.? Also available on Amazon.com and other online booksellers.?

The Mess at Mississauga?

It was early afternoon on Saturday, November 10, 1979, when Canadian Pacific Railway freight train No. 54 began its journey from Windsor, Ontario, to Toronto, a few hours north. But train No. 54 had a few scheduled stops along the way. First, in Chatham it stopped to pick up additional cars from another train coming in from Sarnia—tank cars from the chemical plants there carrying caustic soda, propane, chlorine, styrene, and toluene. Among the additional cars from Sarnia were two Dow chlorine tankers. The train was now 106 cars long. It left Chatham about 6 p.m. and headed northeast to its next stop at London where it made a crew change. As it continued toward Toronto, however, unbeknownst to anyone on the train, one of

its cars was having a problem.18?
As the train rumbled past Milton, some 40 kilometers southwest of Toronto and traveling at about 60 miles per hour, friction had built up in an axle wheel-bearing on Car 33. It was one of the train’s older cars—an old-fashioned type needing manual lubrication for its axle box. Newer, more modern cars had roller bearings. Friction and heat continued to build as the train moved down the line. Residents living near the tracks later reported seeing smoke and sparks coming from the middle section of the train. Further on, others reported that part of the train appeared to be on fire. As the train continued, the axle heat built up to the point where the axle on Car 33 broke off. Then the car started to break apart. At the Burnhamthorpe Road crossing, Car 33 sent its glowing hot wheels flying off the train and crashing through a fence, landing in the backyard of a nearby home. It was now about midnight as the train approached Mississauga, a Toronto suburb of about 300,000 people. The train sped past an area of apartment buildings and suburban homes, now carrying the dangling and damaged undercarriage of Car 33. Just past a light industrial area, at the Mavis Road crossing, the damaged tank car with its dangling undercarriage, left the tracks. Twenty-three other cars followed it off the tracks, causing a deafening crash and metal-on-metal squealing as the iron and steel cars collided and twisted into a tangled pile. Some propane cars burst into flames. Other tankers began spilling their chemical contents, initially styrene and toluene. Within seconds, the leaked liquids and vapors ignited, causing a massive explosion. Yellow-orange flames leapt to 1,500 meters in the sky and could be seen 100 kilometers away. Soon the fire was being fed by the contents of the other wrecked tank cars, with more in danger—eleven held propane, four had caustic soda, three contained styrene, three more held toluene, two box cars were filled with fiberglass insulation, and one contained chlorine.? The undamaged portion of the train, still on the track, had pulled forward and away from the derailment and fire. The sleeping town of Mississauga, meanwhile, began to rouse, as police and fire department switchboards lit up with a flood of phone calls. Within minutes, firefighters arrived at the scene while police set up roadblocks.?
Just as firefighters were about to begin their battle—now early Sunday morning—a violent explosion occurred as another of the propane tank cars blew up. The blast knocked police, firefighters, and onlookers to the ground, showering the surrounding area with chunks of metal. Windows were shattered throughout the area, and three greenhouses and a municipal recreational building were also destroyed. Near the explosion, a green haze was seen drifting in the air. Minutes later, a second explosion occurred. In another propane car, a “bleve” occurred—a boiling liquid expanding vapor explosion—hurling the tank car into the air, spewing fire as it went, finally tumbling into a cleared field more than 600 meters away. Five minutes later, another bleve occurred, sending one end of the propane car about 65 meters away. Emergency authorities and public officials from several governmental levels were being summoned to the scene by this time, as police and fire officials tried to acquire the train’s cargo manifest and emergency procedures. However, the main manifest was in the front part of the train, which by then had moved on to Cooksville, about six kilometers away. About an hour later, a readable copy of the manifest was delivered to emergency officials. Checking the serial numbers of derailed cars, they soon determined that the derailed cars held a mixed cargo of dangerous chemicals, including chlorine, posing a possible chlorine gas threat.?
Chlorine, a deadly chemical, forms a greenish-yellow cloud when released and hovers close to the ground.? A chlorine cloud will follow the terrain as it drifts and disperses—a feature that made it an ideal weapon in the trench warfare of WWI. Once chlorine gas is breathed, it saps the fluids in the linings of lungs and blood, and starts a chain reaction that ends with slow suffocation.? At the wreck site, a chlorine tanker was close to a filled propane tanker, in danger of exploding. The Mississauga fire chief ordered 3,500 residents living closest to the derailment to evacuate. Police officers using loud bullhorns and knocking on doors alerted sleepy residents. Later, as winds shifted and more information about the train’s cargo became known, the area of evacuation was expanded. Shortly after 2 a.m., Metropolitan Toronto

Police sent sound trucks to alert residents of the broader evacuation. The Mississauga section of the Canadian Red Cross Society began setting up resident evacuation centers—one at Square One, a huge covered shopping center about 2.5 kilometers from the derailment. The provincial Ambulance

Co-ordinating Center sent out a general call for ambulances in the surrounding area. Buses were summoned from the Toronto Transit Commission, Oakville Transit, and Mississauga Transit authorities. A team of experts from Dow Chemical at Sarnia, owners of the chlorine tank car, arrived on the scene armed with specialized equipment to execute something called CHLOREP, the chlorine emergency plan. Dow’s Stu Greenwood headed up this effort. But it was soon determined that it would be impossible to seal the leaking chlorine tanker until the propane fires had burnt themselves out. Firefighters, using some 4,000 meters of hose, had nearly a dozen major streams of water trained on the wreck site. Most were aimed at cooling the unexploded chemical tankers, while allowing a controlled burn of escaping gases. More evacuations were ordered as winds changed. At about 5 a.m., the Solicitor General of the Ontario Cabinet was notified. As dawn broke, emergency officials and the town’s mayor met to consider their options. More evacuations followed, including a decision to evacuate Mississauga General Hospital and two adjacent nursing homes. As a few Ontario cabinet officials arrived, the evacuated areas were expanded again by early afternoon, now extending to beyond the Square One shopping center, the site of the first evacuation center. Evacuees there were transferred to other centers. A mass exodus of residents was now underway—some with packed luggage, others abandoning Sunday dinners about to be served. At the day’s end, at least 218,000 residents had left their homes. Others put the number closer to 300,000. “The southern part of Mississauga, Canada’s ninth largest city with a population of 284,000, was a virtual ghost town,” observed one reporter in Derailment: The Mississauga Miracle.?
By 10 a.m. Monday, November 12, at least three propane cars were still burning. Officials feared that one might explode during rush hour, or that chlorine might waft over the area’s highways, trapping thousands of commuters in their cars. The Queen Elizabeth Way, the busiest stretch of highway in Canada, which runs through the central part of Mississauga, was closed at its eastern and western entrances to the town. Commuter traffic to Toronto was rerouted around the evacuated area, causing massive traffic jams. Back at the burning train wreck, a manufacturer of railway tank cars had prepared a steel patch to cover a one-meter hole in Dow’s chlorine tanker. Some chlorine had already escaped, but officials assumed there was more remaining. Railway crews carefully removed box cars and tankers from the area which had not derailed, and attempted to clear debris at the accident site without disturbing the piled-up chlorine and propane tank cars. Staff of the Ontario Ministries of the Environment and Labor monitored the air and found a few pockets of chlorine gas in low-lying areas, but no significant hazard for the general area. Police patrolled deserted streets for looting and checked all vehicles entering the area. Officials would not consider lifting the evacuation order and sounding the all-clear until the fire was out and the chlorine danger ended
On Tuesday, November 13, day four of the ordeal, the propane fire went out at about 2:30 a.m., and the focus moved to patching the chlorine tanker. By late morning, some evacuated hospital patients were being returned to their hospitals just outside the evacuated areas, but the hospital remained closed. By late afternoon that day, the evacuation zone was reduced to a smaller area after air sampling indicated no hazard, allowing 144,000 residents to return home. However, closer to the derailment, the evacuation order held, as there was still concern about chlorine. Workers had been hampered in completely sealing the leaking chlorine tanker, still blocked by another. With an incomplete seal, some chlorine continued to escape. Other tankers, however, were being drained of their contents and hauled away, even as one propane tanker flared up again.?
On day five, November 14, workmen made a risky maneuver lifting and draining a half-empty propane tanker to get at the problem chlorine tanker, gambling that the propane tanker would not explode. Elsewhere on the site that day, a large white cloud of chlorine and water vapor rose from debris. Pockets of chlorine gas monitored in the evacuation zone still presented a health hazard for young children, the elderly, and those with respiratory problems. Frustration grew among some evacuated residents, as a 25-square-kilometer area remained closed. Traffic was still barred at two entrances to the Queen Elizabeth Way.
On day six, November 15, crews worked through the night and early morning, as 20 to 30 kilos of chlorine per hour continued to escape. The steel patch could not be fitted tightly over the rupture. A neoprene air bag was jerry-rigged over the opening which all but completely sealed the tanker, and officials announced there was little leakage. But that did not end the ordeal. Between 7 1/2 and 10 tons of liquid chlorine still remained in the tank. Most of the tanker’s 90 tons of chlorine had been sucked up into the original fireball at the wreck, with the resulting chlorine gas dispersed over Lake Ontario, according to officials. But remaining inside the tanker was a slushy ice mixture of chlorine and water that had built up on its walls from the water poured on by the fire hoses. Scientists worried that this layer of ice might break up and fall into the liquid chlorine, exposing it to the air. This complication delayed the clean-up operation, as it was decided that pumping would not start until favorable winds prevailed. That occurred about 11 p.m. that evening. Still, the remaining 72,000 evacuated residents could not return to their homes that night since the chlorine had not been removed.?
On day seven, Friday, November 16, the problem involving the layer of ice was resolved, and by noon most of the chlorine had been pumped into trucks and shipped safely away. By 3 p.m., after tests showed that no dangerous pockets of chlorine were detected in the area, 37,000 of the remaining 72,000 evacuated residents were permitted to return home. However, the 35,000 residents living closest to the derailment and the first to evacuate, waited another four hours. By 7:45 p.m. that evening, the city was reopened and police removed the remaining roadblocks. Only the derailment site remained off-limits, as there was still wreckage to clean up and one remaining chlorine tank car to deal with. By late evening, the last evacuation center was closed and by midnight, police at the site finished their duties. During the following week, the remaining chlorine tanker was finally emptied and the last pieces of emergency and fire equipment were removed from the scene. The clean up of the wreckage at the site, and of contaminated soils there, would continue for another month or more.?
In the aftermath of the accident, it was clear to many Canadians that Mississauga—and nearby Toronto—had dodged a major catastrophe. “We were lucky we escaped that one,” said Harold Morrison in November 1984. Morrison was chairman of the Metro Toronto Residents Action Committee that formed shortly after the incident. “If the derailment had happened in metro Toronto just 20 miles up the tracks,” he explained, “we’d have had it. Thousands would have died.”19? Indeed, luck had played a role. The derailment occurred just after the train had passed through one of the most concentrated residential areas of Mississauga. The chemically-laden tank cars just happened to leave the tracks at one of the few places where a large area of undeveloped land existed—one of the few such places in all of greater Toronto. And because of the propane explosions at the scene, much of the escaping chlorine was taken up into the fire and into the atmosphere rather than released as a toxic gas along the ground. There had been no fatalities, though some firefighters complained of chlorine exposure. But the Mississauga accident had changed the political and industrial landscape in many ways. As Dow’s Len Weldon would later observe, “. . . It was a big event politically, socially, environmentally, and in every other way. . . ”20

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