Misuse of the knowledge and misapplication of the technology. In other words if you are a dirty polluter with a DNAPL contaminated site then you are going to embrace any and all so called "natural attenuation" literature and or claims. This embracing could even include natural attenuation that works in fractured Bedrock Aquifers due to specific bacteria present that simply do not exist in Overburden sand and gravel aquifers. Natural attenuation is a broad expanse of differing chemical, physical and microbial processes that both together and individually can help to break down contaminants possibly even including chlorinated solvents.
Now of course natural attenuation no matter how effective even in the best of circumstances, under ideal conditions is hardly considered fast. That said current research is finding impressive reductions in Trichloroethylene (TCE) over a decade or more. These reductions in concentration may be from breakdown of TCE or even by enhanced degradation of TCE into cis DCE (dichloroethylene) and trans DCE as well as VC (vinyl chloride. Further chemical degradation would lead to ethenes and ethanes . These degradation products are generally much less toxic than TCE with the exception of VC.
Hence there is studied natural attenuation which can be enhanced for example via soil amendments to stimulate specific bacteria that break down chlorinated solvents such as TCE. Or there is the Uniroyal Chemical style of natural attenuation on their site which is synonomous with the Do Nothing approach. Here those in charge (i.e. the polluter) throw up their hands, shrug their shoulders and say "Dang those chlorinated solvents. Nothing works on them."
When the fox is in charge of protecting (cleaning up) the henhouse the interests of the hens (residents & citizens) are of zero interest to the predator/polluter.
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