Hockessin on Superfund path after well tests show toxic chemicals

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The movement of a toxic chemical plume under the streets of central Hockessin is the likely cause of spiking concentrations of the pollutant PCE at wells that supply drinking water to the area, according to the Delaware Department of Natural Resources and Environmental Control.

While regulators stress that Hockessin water supplied by public utility Artesian Resources Corp. is safe, the state by itself does not have enough money to rid the underground aquifer of the offending chemical, commonly used in dry cleaning.

"That’s why we’ve asked for (Environmental Protection Agency) support,” DNREC Site Investigation and Restoration Administrator Timothy Ratsep said. "The state did not have the financial resources to move forward with investigating it.”

Last week, federal regulators responded, announcing that the EPA has proposed adding the central Hockessin area to its National Priorities List – a designation that would free up federal Superfund dollars to pay for further investigation and cleanup of the underground aquifer.

The 32-acre impacted area straddles Lancaster Pike through the core of the Hockessin business district. 

A 60-day public comment period on the proposed listing began immediately after the EPA announcement on Tuesday.

"The next phase is to continue with the investigation," Ratsep said. "The extent of the (contamination) plume is not known."

Artesian, as well as numerous private wells, draw drinking water from the aquifer. At full capacity, Artesian well sites can supply water to as many as 5,000 homes, company spokesman Joseph DiNunzio said.

Filtration systems have shown to effectively decrease the amount of PCE in drinking water to safe levels, Ratsep said, and there is no need for homeowners who get water from public utilities to purchase filters for tap water, he said.  

Those who use a private well within a half-mile of the contaminant plume under the core of Hockessin, and do not have a water treatment system, should contact DNREC's Hockessin Groundwater Site Project Manager Robert Asreen at Robert.Asreen@state.de.us.

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The EPA, in its announcement last week, also finalized the addition of a Newark aquifer to the federal Superfund list, a move that was officially proposed last summer. PCE also is the offending chemical in that case.

State regulators suspect someone at a business in a southeast Newark industrial area, possibly decades ago, allowed PCE to leach into the ground.

They also believe Hockessin's PCE pollution occurred long ago – in the 1980s or earlier, Ratsep said. At that time, the chemical went largely unregulated, leaving businesses free to dispose of it any way they chose, he said. 

"It was basically at the owners' discretion," he said, "and a lot of them had disposed of it by throwing the material out their back door."

New regulations imposed since require individuals who possess the chemical to document its location at all times. For that reason, the state believes Hockessin's PCE releases are not recent. 

Yet, an email circulated among officials at the EPA earlier this month said, "historicaland current operations appear to have contributed to the groundwater contamination." 

An EPA spokesman did not respond to questions about evidence of current groundwater contamination.

Ratsep is unaware of any data showing recent pollution, he said, but noted that more investigation is needed. 

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The PCE plume first was discovered in the Hockessin aquifer in the early 2000s. Shortly after, the EPA funded a preliminary pollution assessment.

Regulators initially considered nine companies as potential sources of the contamination – four gas stations, four dry cleaners, and an auto mechanic's garage.

After tests of soil and groundwater at the properties themselves, they zeroed in on two dry cleaners as likely culprits, Ratsep said.

Owners of the companies, Hockessin Cleaners and Sunrise Cleaners, could not be reached by phone for this story. 

While PCE also has been widely used in textile processing, the chemical was not found at Hockessin's nearest textile facility, National Vulcanized Fibre Corp. in Yorklyn, Ratsep said.

"Right now we have not identified any other sources, but that’s part of the investigation," he said. "At this time all we know is that there are two sources. 

The National Institutes of Health says PCE is “reasonably anticipated" to be carcinogenic. People who have experienced chronic exposure to the chemical could see damage to their livers, kidneys, skin, and nervous systems, according to the Centers for Disease Control.

Newborns could experience "adverse effects" through maternal exposure, according to the agency. 

Environmental regulators also have discovered lower levels of other toxic chemicals in Hockessin's groundwater. For example, perfluorinated compounds, or PFCs, were collected from groundwater near Hockessin Memorial Fire Hall.

The finding confirmed "whether the use of certain firefighting chemicals potentially could have contaminated the groundwater," stated a letter to the EPA sent by technicians from West Chester-based Weston Solutions.

Weston Solutions has been contracted to test area groundwater, and it was the company's technician who found PCE levels in Hockessin to have spiked during the past year.

One analysis at a domestic well in 2016 recorded PCE at 4.5 parts per billion. A year later, the level jumped to 50 parts per billion. The tests were conducted on raw water before treatment with charcoal or other filtration systems.

The state of Delaware's maximum allowable contaminant level for PCE in drinking water is one part per billion. The EPA's maximum is five parts per billion.

Wells could be recording higher levels because the pollutant plume is drifting, moving closer toward them, Ratsep said.

"It could be that the last part of the contamination finally got to the wells," he said. "It’s not that there’s a new release, just that the historical releases are finally getting to the wells.”

Artesian frequently tests its water, DiNunzio said, and his company's well sites have not received a violation from the state, as post-treatment water tests nearly always meet Delaware's strict standards. Though water from one well recently tested 1.1 parts per billion, DiNunzio said.

Tests in 2001 after the chemical first was found in Hockessin showed PCE levels surpassed federal limits at two wells.   

"But what we will do is shut that down until we get more treatment," he said. 

Asked if regulators are doing enough to curb PCE pollution at its source, DiNunzio said "I'm going to reserve comment.”

"It is always best from our perspective that things are addressed at the source," he said.

Contact Karl Baker at kbaker@delawareonline.com or (302) 324-2329. Follow him on Twitter @kbaker6.