In the 1980's, Stauffer Chemical Co. and its successor, Formosa Plastics, were named as responsible parties for the chemical contamination found in groundwater in the Potomac Aquifer near Delaware City, DE. The toxins discovered included vinyl chloride, ethylene dichloride and trichloroethylene. At the time, officials reportedly expressed confidence that this contamination would not impact nearby water wells. Apparently they were wrong:

Earlier this month, Delaware’s Department of Natural Resources and Environmental Control notified owners of four properties near U.S. 13 and Wrangle Hill Road that they would be eligible for free United Water Delaware connections. The offer followed the unexplained appearance of a cancer-causing chemical, ethylene dichloride, in a well near the St. Georges Getty service station just north of the car dealership.

Officials had assured area residents for more than two decades that pollution from the site of the old Stauffer Chemical Co. toxic-waste landfills to the north was under control. That they were wrong underscores how little is known about how toxic chemicals make their way through complex geological formations into drinking-water supplies.

[...]

By 1982, the plant became Delaware’s seventh named toxic cleanup site following passage of the federal “Superfund” cleanup law, and one of the first to become a federally overseen project. Stauffer and Formosa eventually were ordered to remove pits containing vinyl chloride processing remnants, and to begin pumping and treating more than 400,000 gallons of contaminated water daily from around the site.

Investigators acknowledged decades ago that water “goes in all directions” from the site of the lagoons. But their initial confidence in the safety of deep aquifers used by water suppliers proved misplaced.

Although an EPA report in 1986 said that layers of clay shield the deeper Potomac aquifer from chemicals in more shallow wells, federal officials have since reported discovery of ethylene dichloride in the deepest wells, and in 2006 reported “no evidence” that the overall contamination had been contained in one portion of the upper Potomac Aquifer or the shallow aquifer above it.

It may be worth noting that when TCE degrades under ground, it can result in the formation of new toxins including ethylene dichloride and vinyl chloride. This is known as TCE's degradation pathway.

Also, much of the article talks about alternate uses of the contaminated water but fails to mention anything about toxic vapors or vapor intrusion:

“[The water is] just no good. It’s contaminated. The only thing we can use it for is washing the cars,” [resident and local car dealership owner Charles] Stapleford said.

and

Shazim Uppal, who owns the St. Georges Getty station at Wrangle Hill and U.S. 13, said he was unaware of the current cleanup debate. He is sure, though, that the tainted water near his business prevents the company from selling fountain-type drinks or using plain tap water from a company well.

“We bring in bottled water. If they can put in a pipeline, that would be good. We only use the water in the sink here for cleaning the floor,” Uppal said.

Hey folks, these toxins evaporate into the air. They can be toxic to breathe. Why haven't these people been advised of this by state officials or by EPA?

As always, we'll keep you posted as we learn more. Meantime, you can read the full story here.