Four licensed landfill companies are being held responsible for dumping 800 tons of garbage brought by 17 trucks on an abandoned auto racing track in Fengxian District, said the district government.
The city's environment authority is evaluating the damage caused to the land before a charge is placed against the polluters.
Nineteen people were arrested last weekend after they were deemed responsible for the trucks that ferried construction waste and household garbage to Dayin Circuit in Fengxian's Haiwan Town.
When authorities arrived at the scene on Christmas Eve after receiving tip-offs, they found that 10 trucks had already dumped their load into a pit, while the remaining seven were abandoned near the road. Seven drivers escaped from the scene and 10 were caught.
The district's urban management bureau told thepaper.cn that investigation showed the trucks were rented and unlicensed, and the garbage was transferred by the trucks from four licensed landfill companies.
The names of the companies have not been released.