BEIJING - Over a year ago, a government-run newspaper warned that a boomtown in southern China would run out of space to dump the waste left behind from a building frenzy.
On Sunday, a mountain of mud and construction waste collapsed at an industrial park in Shenzhen, the rapidly growing town next to the border with Hong Kong, burying 33 buildings and leaving nearly 100 people missing.
Besides new buildings, a network of subway lines is being built in Shenzhen, and mounds of earth are being excavated and dumped at waste sites.
The official Shenzhen Evening Post, published by the city government, quoted an unnamed official as saying in October last year that choosing somewhere to locate these dumps was becoming"exceedingly difficult" and that it was "the only thing" on his mind. "Shenzhen has 12 waste sites and they can only hold out until next year (2015)," the newspaper said.
The frequency of industrial accidents in China has raised questions about safety standards following three decades of breakneck growth in the world's second-largest economy.
Provincial authorities sent a team to investigate the Shenzhen mudslide, the Ministry of Land Resources said.
The amount of mud and waste at the site was immense and was stacked too steeply, "causing instability and collapse, resulting in the collapse of buildings", the ministry said in a statement.
Fan Xiao, a senior engineer at the government-linked Sichuan Geology and Mineral Bureau, said such risks from man-made mountains were prevalent nationwide, especially as China also has many slag heaps from the mining industry.
"Shenzhen is a modern city after all; ultimately its management standards are pretty high. It is possible that some other cities have not reached Shenzhen's standards of management. Now that Shenzhen has this problem, you can't rule out a lot of other places having such risks," Fan said.
Shenzhen is supposed to be a model, modern city for China. Once a quiet fishing village, it was chosen by Beijing three decades ago to help pioneer landmark economic reforms, and it has boomed ever since.
The waste site that collapsed on the industrial estate was only supposed to have had a lifespan of around a year and should have stopped operating in February this year, according to the Shenzhen government's online news portal.
But workers said it continued to take waste mud, the report added.
Shenzhen media has reported several times in the past few years that companies were illegally dumping construction waste as the legal dumps were all full.
The Shenzhen government did not respond to requests for comment.
Another local newspaper, the Shenzhen Special Economic Zone Daily, said companies were becoming so desperate that even old ponds once use to farm fish were being filled by building waste, though low-lying land and mountain hollows were preferred.
Such dump sites were often forced through despite opposition by residents, media reports said. Environmental impact assessments were likely skipped, they said.