Note: This story has been nominated for a National Newspaper Award .

LAC-MÉGANTIC, QUE.—Sherbrooke fire chief Gaétan Drouin stood on the bridge spanning the Chaudière River, the winding tributary that divides Lac-Mégantic . The town burned violently before him. Noxious smoke, thick and pungent, filled the air. Even stronger was the faintly sweet smell of light crude.

His flashlight beam cut through the darkness, down to the water cascading from the town’s namesake lake into the river it feeds.

Green-yellow oil, slick and bright, had overtaken the river, and was gushing downstream.

When a 72-car train of explosive crude barrelled into the town early on Saturday, July 6, it killed 47 people, levelled buildings, ripped away livelihoods, and annihilated the heart of the downtown.

It also unleashed nearly six million litres of oil.

The deluge glugged out of punctured tanker cars and ran down city streets ablaze, a river of burning oil. It seeped into the ground, gushed down manholes into the sewers and stormwater pipes, causing powerful explosions underground. It spilled into crystal waters of the lake, clung to boats in the marina, and rushed down the winding Chaudière, a 185-kilometre river that empties into the St. Lawrence.

As firefighters battled the blaze, a growing army of environmental emergency experts descended on the town to stop the spread of the volatile Bakken crude, a substance slightly thicker than vegetable oil. With every minute, it extended its reach deeper, further, threatening to sicken communities, poison the air, and ruin ecosystems.

They have been on the ground ever since, fighting a toxic villain that, even now, is on the move.

The spill in an urban setting has destroyed buildings untouched by flame, prompted a mass exodus of contaminated soil, and forced crews to rebuild even as they decontaminate, with the aim of jumpstarting the faltering economy.

Those leading the clean-up sum it up simply: There has never been anything like it.

Stop the bleeding

By the time Jean Campagna arrived in Lac-Mégantic from his home outside Sherbrooke, the fire had been raging for eight hours. Like so many others, he had been summoned by a dead-of-night call. The day before, he had clocked out at 4:30 p.m., ready for his vacation.

The technician with the Quebec environment ministry’s emergency team approached the blaze at the mouth of the river, near the bridge, when he arrived at 9:45 a.m. His eyes were drawn to a torrent of crude gushing into the river from a two-foot storm pipe.

“The first thing we had to do was absolutely stop that as quickly as possible,” he said. “I knew that there were drinking water intakes downstream, and I knew that it was running strong through the pipe. It was practically pure oil.”

Scanning the scene, he saw allies in municipal workers and environmental emergency employees, and began co-ordinating — a role he has played ever since, as a clean-up project technician. He held a five-minute meeting near the bridge, planning a joint assault.

Everywhere, there was work to do.

When oil escaped from the tankers beginning at 1:14 a.m., some of it immediately burned. The rest travelled in two main directions: on the surface of the ground, towards the lake; and underground, infiltrating soil and pipe networks.

On the surface, burning oil moved downhill from the derailment, shooting with flames as it flowed towards the lake. Streetlamps melted and shoreline rocks fractured as the fiery crude entered the water. The oil was still burning as a strong wind sent it back to land, where it hit the rocky shore of downtown’s Parc des Vétérans.

Oil seeping into the ground gravitated towards the highly permeable material known as backfill, usually a mixture of sand and gravel. Backfill blankets parts of the town and lines the underground infrastructure, including pipes. In some areas, it travelled three metres deep, until it hit a thick, mostly impenetrable layer of natural clay. Like water on a table, it spread out horizontally.

Hot crude infiltrated Lac-Mégantic’s sewer pipes by seeping into the foundations of the destroyed buildings that led to the basement floor drains, which are connected to the sewage network. It found entry through connecting joints, or simply melted the pipes, on some streets made of plastic known as PVC. From there, it travelled to the water treatment plant, inundating it with oil.

Finally, hundreds of thousands of litres ran down the streets into storm drains, where fumes caused explosions. On the residential street Rue des Vétérans, the underground blasts sent manholes flying up to 10 metres high. At a storm pipe that empties into the river more than a kilometre away from the impact zone, burning oil went shooting out, like a rocket blasting off.

Emergency actions by quick-thinking first responders stopped the contamination from becoming much worse.

Firefighters, municipal workers and police watching the oil flowing down manholes and storm drains desperately shovelled soil into its path. Firefighters heaped gravel into the gap underneath the marina quay, trapping the oil before it could run to the mouth of the river. Others frantically shovelled earth down a manhole, trying to stop the oil from travelling to the sewage treatment plant.

In one important move, a crew of volunteer firefighters, workers from the nearby factory, and Tom Harding, the train’s engineer, removed nine tanker cars that remained on the tracks, on the north end of the blaze, close to the town’s church and blocks of residential streets. So close to the fire, the cars were ticking time bombs.

Sylvain Grégoire, an employee from the nearby particleboard plant, rushed to the factory at 3:25 a.m. to get the company’s rail car mover, called a Trackmobile. At the factory, it moves small rail cars filled with wood. He hoped it would pull tankers far larger and heavier. An hour later, he was steering down the sloping track, towards the blaze.

“I thought of my kids,” he said. “I wondered, what if it explodes?”

At 8 a.m., all nine cars, together containing 961,000 litres of crude, had been moved to safety, several hundred metres away from the blaze.

By the time Campagna and his ministry colleagues arrived, Eastern Canada Response Corporation (ECRC), a company specializing in marine oil-spill response, was setting up booms — long, thin and buoyant tools that catch oil on the surface of the river and lake.

The strong current meant crews could not simply string booms across the river, because the oil would just flow underneath. They configured some in alternating rungs, deflecting the oil from one to the next until it reached a collection point. From there, the oily water was vacuumed up with surface skimmers, and collected in tanker trucks.

Back at the bridge, Campagna and others tried to stop the flow of oil gushing from the storm pipe into the river.

They decided to place an inflatable plug directly into the pipe, trapping the oil and stopping the hemorrhage. But the oil was gushing so strongly it was difficult to put in place.

A vacuum truck was sent to a manhole further up the pipe, closer to the impact zone, where it began pumping to intercept the oil flowing downpipe. The level of oil significantly lowered, a worker descended into a manhole to place the plug. Because of the toxic vapours inside the sewers, he was strapped into a harness, so the crew could pull him up quickly if he was hurt.

Another truck was brought in to suck up the oil collecting at the plug. There would be a constant procession of 15 tanker trucks — filling up, leaving, coming back — for the next three days.

Campagna and dozens of others worked into the night, plugging other pipes, sucking up thousands of litres of oily water from the lake and river, and setting up what would ultimately total more than three kilometres of boom.

Overnight Saturday, fire crews considered simply letting the inferno burn out on its own, a tactic sometimes used to reduce air contamination. The higher the temperature of the fire, the less smoke it produces, meaning that when you blast a fire with water and foam to cool it off, air pollution is increased.

But the amount of oil they knew was left in the tankers could mean the fire would burn 10 more days. All the while, oil would continue to gush into the ground.

“The faster we were able to put out the fire, the faster we would be able to work on the migration of the oil in the soil,” said Drouin, the Sherbrooke fire chief.

Fire crews chose to attack the blaze, trucking in specialized foam. Just before noon on Sunday, 36 hours after the derailment, the blaze was extinguished. Firefighters were still cooling the charred, steaming ground well past sundown.

Rehabbing the river

The helicopter rotors thudded as the survey team flew along the winding Chaudière River on July 7, the day after the derailment. A blue metallic sheen, spanning the width of the river for 80 kilometres downstream of Lac-Mégantic, confirmed serious contamination.

In total, 100,000 litres of oil spilled into the Chaudière.

For the first few days after the derailment, Sonia Laforest, a shoreline restoration scientist with Environment Canada, documented the oil’s travel from the helicopter window, part of a team brought in to evaluate the contamination of the lake and river, and provide scientific and technical advice to ECRC, the marine oil spill company, and other first responders.

The fly-overs determined the contamination had been mostly confined to 120 kilometres of shoreline. But crews would have to walk the riverbanks to understand what areas were hardest hit.

The crude that spilled in Lac-Mégantic had more light fractions than heavy, which from a clean-up perspective has significant advantages. While heavier crude may have sunk slightly in the water, this crude has floated on the surface, making it easier to trap with booms. It also meant there would be no black, tarry residue on wildlife and plants because it is not sticky enough to form large clumps — think molasses versus vegetable oil.

The danger is that lighter oil is more prone to penetrating sediment, which can set off a chain reaction, contaminating vegetation and wildlife.

A week after the disaster, the parties tasked with cleaning the river launched a clean-up process called SCAT, Shoreline Clean-up Assessment Technique. The exercise is simple but tedious: workers travel on foot, methodically documenting signs of oil on the shoreline’s banks, beaches and vegetation. The process is like environmental triage.

Four teams were formed, made up of officials from Environment Canada, Quebec’s environment ministry, clean-up company ECRC and the municipal government. They began at the mouth of the river, near the town, looking for oily sheen on the water, green residue on banks, slimy vegetation — anything indicating contamination.

Days usually began at 5 a.m. Even then, the July sun quickly made sweat run down their necks. They wore rubber gloves, boots, pants, life jackets, hats, and lugged backpacks filled with a day’s worth of water, lunch and bug repellant. Some days, temperatures reached the mid-30s. Others, intense rain beat down.

Laforest, who has spent her career trudging along contaminated shorelines, including in South Korea after a devastating spill, found the heat, rain and the problems accessing the shoreline overwhelming at times.

“It was the most difficult I’ve ever walked.”

More at thestar.com: Ottawa announces how $60M will be spent to rebuild

The SCAT evaluation continued through August and September, crews walking a total of 275 kilometres. The results showed that approximately 40 kilometres of both rocky and sandy banks needed immediate cleaning.

Armed with these results, Quebec’s environment ministry sent out a crew of 200 workers in September and October. On rocky shores, they used rakes or low-pressure hoses to roust oil residue from the shoreline. It then floated on the surface of the water, downstream to absorbent booms.

On sandy embankments, there was a risk of erosion, which can be traumatic to the shoreline ecosystem. Rather than the harsh rakes or low-pressure hose treatment, crews ran water down the bank using a perforated pipe, simulating rainfall, which then sent oil in the sediment back into the river, again to be caught by booms.

More shoreline clean-up may continue in the spring. Experts await test results of water organisms to reveal if contaminants have infiltrated the food chain.

Intakes for the three towns that source drinking water from the Chaudière were reopened in September after being closed since July 7.

In August, clean-up crews also had to tackle the marina, where oil had clung to 101 boats. One by one, the boats and the marina’s quays were removed to be pressure-washed inside a massive basin built nearby, which collected the contaminated run-off so it could be treated. Rocks that line the marina bank were washed the same way, booms catching oil re-entering the lake.

Attacking the air

In the initial days, the focus was on investigation and victim recovery. Access to the “red zone,” the impact area, was mostly restricted to Transportation Safety Board officials, police, firefighters and forensic experts searching for human remains.

For them, the danger had shifted from fire to the toxins in the air.

From the early hours of the disaster, a team of air contamination experts had arrived from Quebec’s environment ministry, driving a Trace Atmospheric Gas Analyzer. The blue bus the size of a motorhome is a lab on wheels, called upon in environmental emergencies. Air intakes placed outside the bus allow technicians to detect toxic components of ambient air.

The Center for Toxicology and Environmental Health, an American firm, was also on hand, one toxicologist flying in from Little Rock, Ark.

Among the major dangers that experts watched for was carbon monoxide, which can be produced when organic materials burn. They also looked for volatile organic compounds (VOCs) — chemicals that get into the air when they evaporate from the oil. Common VOCs produced by petroleum products are benzene, toluene, ethylbenzene and xylene. All are damaging, and benzene is carcinogenic.

Those investigating or searching in the area wore masks that filter out dangerous chemicals, while air contamination experts ensured toxins did not surpass a level the respirators could purify.

Air experts were also monitoring vapours that could explode, a risk that was highest when workers began removing oil left over in the derailed tankers beginning July 14. Crews knew dangerous, potentially explosive vapours could be built up inside, and conducted a series of tests before tanks were opened.

Once in the clear, the carcasses were cut with a water drill, to avoid dangerous hot spots. A temporary road was built through the impact zone to allow machinery to come and go. After the tankers were emptied and clean, Transportation Safety Board officials removed sections of the tankers they needed for analysis in the board’s Ottawa lab.

Throughout the process, firefighters were on hand to keep the tankers and the oil cool with Class B foam, used on flammable liquids to smother vapours that could ignite.

By the end of July, 740,000 litres of oil was collected from the tankers.

Trench warfare

By August, the “red zone” more closely resembled a construction site than a disaster area.

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All the tank cars had been destroyed, the carcasses cut down and recycled. Gone, too, was debris that had littered the impact zone — railroad ties, warped tracks, concrete foundations of ruined buildings. All had been removed by heavy machinery, then recycled or burned.

Now dotting the landscape were dozens of oil recuperation trenches, dug by excavators carving deep troughs into the soil. The trenches collected the oil already in the soil, and stopped its possible spread to other areas; they were placed strategically to divert the crude from entering sewer or storm pipes.

Tanker trucks were in constant motion, sucking up the oily water the trenches spat up, then bringing it to a mobile water filtration facility set up near the sewage treatment plant.

Throughout the summer, crews had also been concerned about rainwater passing through the contaminated pipes, sending oil through once more. They installed plugs throughout the network beneath the disaster zone, then stationed tanker trucks at manholes to vacuum up water collected inside.

They had to keep an eye on the weather. If rain was forecast, they had to make sure extra vacuums and tanker trucks were at the ready to suck up the water gathering inside the pipes.

“We were afraid of storms, because we weren’t sure we would be in control,” said Campagna. “The water goes in, it has to be able to go somewhere.”

To prepare for the rain and snow beginning to fall through winter into spring, crews created a collection system that directs water flowing through the downtown soil into one of five wells situated around the site. Water gathered inside is then pumped into a massive recuperation basin, located in the heart of the impact zone, capable of holding as much as four Olympic swimming pools’ worth of liquid.

From there, the water is drawn into a small white portable that contains a filtration system. The treated water is tested daily, then released into the river.

Throughout the five months since the disaster, environmental consultants have been extracting samples all over the downtown. Their results give analysts two vital pieces of information: where the oil had spread, and the level of contamination.

In Quebec, soil contamination by oil is categorized by potential use. Mildly contaminated soil can still be used for residences and recreational facilities, while moderately contaminated soil can be used for commercial and industrial use.

Much of the 69,000 cubic metres of soil contaminated in the impact zone alone, however, is beyond use in its current state. Preliminary tests revealed higher than accepted levels of benzene, as well as metals including copper, arsenic and lead.

Two other low-lying downtown areas were also deeply contaminated. Oil had seeped into the soil underneath a restaurant near the marina, and an ice cream store close to the river. Both buildings had to be demolished.

As testing went on, oil-rich earth was heaped in piles that just kept growing.

Building a toxic mountain

As a harsh November wind whipped gusts of snow back and forth, Campagna stood next to vast mountain of Lac-Mégantic’s sickest earth. The compact pile stood two storeys tall, spanned a platform larger than a football field, and held 25,000 cubic metres of toxic soil.

It is the first of three mounds that will soon form a contaminated mountain range on the outskirts of town.

The decision to store dirty soil off site was clinched after government leaders decided the town’s economic heart needed to be jolted, as soon as possible.

That meant two things: rebuilding the railroad track, and constructing four commercial condo buildings that would host some of the destroyed impact zone businesses , allowing them to reopen as early as February. Both sites now lie in or around the impact zone.

Their construction prompted a “big, big adaptation” of oil clean-up procedure, said Paul Benoit, a deputy director with Quebec’s environment ministry. He arrived to manage the clean-up shortly after the Quebec government appointed Pomerleau, a construction firm, to take over responsibility for cleanup from the insolvent rail company Montreal, Maine & Atlantic.

“Usually, what we do is we decontaminate, we treat the soil, and then reconstruct,” he said. “That’s the logical sequence.”

To ensure the track and the future commercial buildings were not built on polluted land, crews had to thoroughly test the ground underneath.

Beginning in August, the tests revealed the presence of more oil than anticipated. As it turned out, Lac-Mégantic had a series of abandoned underground pipes, long since forgotten by the city. Oil had congregated inside.

It was only the first surprise. Later in the month, crews found an intact car underground that they believe had been there for at least 25 years.

Not long after, the town’s old railway roundhouse, which is a service building for locomotives, was found two metres underground. Decades ago, Benoit said, it was thought to be easier to simply bury unwanted structures than to dismantle or dispose of them.

Crews decided construction in the disaster zone would be easier if the vast amounts of soil were kept on containment pads. They were equally concerned about contamination spreading if the oil-soaked earth stayed put.

At the end of August, they began building three containment platforms on a vast swath of unused land next to Tafisa, Lac-Mégantic’s particleboard factory two kilometres from downtown.

The forested ground was razed, then made into a layer cake of protective measures: an impermeable membrane, underneath an impenetrable cloth reinforcement, underneath an asphalt platform.

Soon, a cavalcade of dump trucks was ferrying soil from the downtown to the platforms, beeping as they unloaded before going back for more.

For now, the platforms are simply for storage. But the soil may also be treated here, depending on the decontamination method chosen. Among the options to remove the oil is injecting bacteria or chemicals into the piles, promoting oxidization that cleanses soil. This could be done on site.

This week, the Quebec government closed its call for tenders for the decontamination of 558,000 cubic metres of soil, which includes the contents of the pads as well as soil that has not yet been removed.

Whatever treatment is chosen for the piles, the aim is to have the cleaned soil return to fill the downtown’s holes by next winter.

In 2013, the Star's Wendy Gillis reports on the monumental cleanup and decontamination following the disastrous MMA train derailment.

Those working to restore the core hope that timeline sticks. Throughout the clean-up, they have been under intense public scrutiny.

Each day since the disaster, locals and visitors have observed their actions closely, eager for signs of progress. Criticism lately is that crews are just moving around piles of soil.

“They watch us work, they ask questions. And us, on the other side of the fence, we would look at them,” Campagna said. “For some of us, it’s encouraging. For others, it’s irritating.”

He looked downhill, towards the downtown, then reached gloved fingers into the base of the contaminated mound, raised a fistful of the soil to his nose and nodded. He could still smell the oil.

Into the unknown

At night, lampposts light the surviving stretch of quaint storefronts on Rue Frontenac, inside the disaster zone. The buildings appear unscathed, frozen in time at the moment before the disaster destroyed some 40 buildings steps away.

A children’s store advertises new and used clothing. A sign on a green, three-storey apartment building announces furnished rooms for rent. On Rue des Vétérans, a residential waterfront street two blocks south, pretty bungalows bear no obvious signs that a river of burning oil had run down one street over. Inside one home, a dining room lamp shines bright, suggesting someone’s inside.

No one is, of course. When work here ends for the day, it becomes a ghost town. The contamination and ongoing construction has blocked public access until at least June 2014. A security firm guards the tall fence that surrounds the restricted area.

The damage to some buildings here goes unseen, but could prove just as devastating as explosions and flames. If enough oil seeps into the foundation of a building, it becomes too dangerous to inhabit. Over time, it will release toxic vapours, such as benzene, or methane, an explosive gas.

The province and city are still deciding what to do with these buildings. Playing a role will be whether insurance companies will pay to decontaminate the foundations of buildings — something that can be done with major renovation or prolonged cleaning. Some buildings, however, may be beyond repair.

Denis Bolduc, the owner of a shoe and clothing store on Frontenac, isn’t sure he wants to move back into his three-storey building. If it can be saved, it could be three years before he re-enters. By then, he will be well established in his new location in the commercial condos, which opens in February.

He is concerned, too, about an unease that lingers above the once-beloved downtown. He feels that some people want a fresh start — they don’t even want him bringing stock from the Frontenac store to the new location.

“There is a psychological problem in the region,” he said.

In late November, as the final sections of railway were put into place in the distance, residents peered through the fence.

Soon, they will see the train re-enter town, travel down the same stretch, pass through the area its predecessor destroyed. It will be hard to watch. It will also be the first sign this sick land will heal.

Clean-up, by the numbers

5.9

Millions of litres of oil spilled

$200M

Estimated cost to clean river and downtown

558,000

Cubic metres of soil the Quebec government determined needs decontamination

3,369

Metres of boom set up on the river, lake and marina at height of clean-up

275

Kilometres walked conducting the Shoreline Clean-up Assessment Technique process

500