"We basically nuked a town with chemicals so we could get a railroad open"

[ProfessorGAC]

12. The Biggest Danger...

...which burning doesn't solve is the micro/nanoscopic particles of low molecular weight PVC.
Vinyl chloride reacts with atmospheric moisture to form a polymer but uncontrollable mass transfer results in termination at low oligomer weight.
That stuff isn't there to burn. It's already on and in the ground so not part of the fuel.
It's a moderate health hazard but a substantial environmental issue. Geez, there's too much microplastic in the environment already.
And, if in fact they burned in place, burning without scrubbers concerns me because of the release of hydrogen chloride & chlorine gasses.
The initial release to prevent explosion seemed wise to me. This remediation method is highly suspect.