The environmental legacy of coal gas plants

Years ago, I provided litigation support for a consortium of reinsurers of the sites of former coal gas plants. Utilities around  the US had inherited these sites. Those in this lawsuit were in the Midwest, but every town had at least one coal gas plant at one time.

Now we know about the numerous toxins and carcinogens in coal and coal tar, a residue of coal-gas production. But there was a time when people discarded it in tar wells—essentially just holes in the ground. So the old coal gas plant sites needed cleaning up. Who should pay for it?

The insurance companies were responsible only for the policy period, which in this case began after the coal gas plants had closed. The utilities claimed that during the operating period, the plant owners had not known that coal tar was harmful. Because these insurers had issued policies on many such sites, it was worth it to them to conduct a thorough investigation of the history of coal tar and the environment. That way any legal precedents our case set would have a solid factual basis.

An important question when working with historic projects is, “What did they know and when did they know it?” That is, what could plant operators have known about the environmental effects of coal tar? In forensic work we investigate building codes, standards, and professional journals of the day to help determine potential liability. No one can use a building code that doesn’t exist yet, or be aware of discoveries yet to occur. On the other hand, it’s often surprising how much our predecessors did understand. Even if they didn’t fully understand, their empirical knowledge may have been enough to keep them out of trouble.

Literature review

As it happened, the Institute of Gas Technology (now the Gas Technology Institute) was conveniently near our offices. Their library had journals dating back to the earliest days of gas technology in the US. Not surprisingly, only the issues from the previous few decades had been digitized. As we perused the older issues, we found that the tables of contents didn’t include everything of interest. We needed to page through every single issue for what we needed.

As we did so, we found that the coal-gas industry in its early days was a close-knit community. Their journal of choice reported not just industry news, but personal milestones and the doings of family members. In those days, technology transfer often meant traveling to plants in other countries to see how they did things. There was a rather harrowing account of the capture of some American visitors to a Philippine gas plant by Japanese forces during WWII. (The Americans were later released in a prisoner exchange. Their Pilipino colleagues kept the plant going under occupation using whatever raw materials they could get.)

Not just the scientific literature

One of the most useful features of the gas technology journal was a summary of court cases involving the coal gas industry. Several cases from the early 1900s involved neighbors of coal gas plants who sued because of contamination of their well water. And a 1912 case involved a plaintiff whose oyster beds were downstream from a coal gas plant. In the courtroom, he added coal tar to a container with one of his oysters, and the oyster died. The jury found for the plaintiff. We were able to supply docket numbers and other details to the attorneys.

Later issues contained scientific papers in which university scholars examined the effects of coal tar on various species of fish. It was clear that the “gas men” must have known coal tar wasn’t benign.

Even the ads were surprisingly useful. The quest for synthetic quinine to treat malaria had led chemists to use coal tar as a resource. While coal tar never yielded quinine, it did have many other commercial uses—everything from medicines to dyestuffs. Mauve was the first aniline dye; other colors followed. Once coal tar had a commercial value, plant owners would rather sell it than discard it. We used the ads to document when buyers of coal tar began to operate in a given location. After that, there would have been less reason to discard coal tar.

How Green was my Valley

Abandoned historic coal mine
Abandoned coal mine. Shutterstock image.

No one would read the classic novel How Green was my Valley as an environmental treatise, but environmental destruction is one of its themes. Indeed, contamination from coal slag was one reason why so many Welshmen had to emigrate.

Below us, the river ran sweet as ever, happy in the sun, but as soon as it met the darkness between the sloping walls of slag it seemed to take fright and go spiritless, smooth, black, without movement. And on the other side it came forth grey, and began to hurry again, as though anxious to get away. But its banks were stained, and the reeds and grasses that dressed it were hanging, and black, and sickly, ashamed of their dirtiness, ready to die of shame, they seemed, and of sorrow for their dear friend, the river.

“Will the salmon come up this year, Mr. Gryffydd?” I asked him….

“I am told,” he said, “that no salmon have been seen these two years.”…

“Good,” I said. “No one shall tell me again that fish have got no sense with them. Pity, I do think, that more of us are not thinkers like the fish.”—Richard Llewellyn, How Green was my Valley, 1939

The story takes place in Wales in the late Victorian era. That’s not enough to indicate that the Victorians understood how harmful coal byproducts can be; novels may contain anachronisms. But the novel itself dates from 1939, before the beginning of the policy period in our case. That’s why I suggested the above passage to the attorney as possible material for his closing argument.


In litigation support, your report must list the documents you referred to in your investigation. Each side must make these documents available to the other. Apparently How Green was my Valley stood out among all the technical documents. My colleague who testified in court told me the plaintiffs’ attorney asked him about his expertise in it. Fortunately, Allen was able to testify in a suitable accent that he was a Welshman, and that he remembered coal gas plants from his childhood. I don’t know what the attorney hoped to get from that line of questioning.