WILMINGTON — The U.S. Environmental Protection Agency held a joint virtual meeting with the Massachusetts Department of Public Health last Wednesday evening about the EPA’s recovery plan at the Olin Chemical Superfund Site and the Wilmington Childhood Cancer Study. There, the two organizations took turns presenting to the public before representatives from Wilmington responded.
Alicia Fraser of Mass DPH shared the results of the Wilmington Childhood Cancer Study for the first time. She explained that concerns were raised by concerned residents in 1999. A study on the screening level of cancer incidents at the time identified an unusual pattern of young cancer rates with no explanation. Then, in 2002, they found 23 cancer diagnoses between 1990 and 2000 in an environmental epidemiological study.
The results of the 2003 study showed that NDMA contamination from Olin was present in the groundwater that feeds the city’s drinking water. The contaminated wells were subsequently taken offline.
“Over the next decade, many people have worked to understand the historical contamination and exposure,” Fraser said.
They also found TCE exposure with no known source of origin. Both chemicals, she confirmed, are carcinogens.
The results of the full study showed that children whose mothers had ever been exposed to NDMA were 2.2 times more likely to develop cancer. The odds ratios for children whose mothers were exposed during pregnancy was 3.0. However, no association was established if the children were exposed to NDMA and TCE only after birth.
This meant, according to Fraser, that there was a link between childhood cancer and prenatal exposure to NDMA, possibly NDMA and TCE combined.
“Our findings are best understood as a possible increase in risk at the population level, not determining causation at the individual level,” she continued.
For the record, she also stated that childhood cancer rates in the city have returned to normal since 2001 and that the city’s public drinking water is no longer polluted.
Afterwards, representatives of the Environmental Protection Agency discussed remediation plans for the Olin site. Project manager Melanie Morash determined the contamination risks of the exposure: health risks when used as drinking water, soil contamination when used as a home, indoor air risk when building buildings and ecological risks for birds and small animals.
The EPA had reached preliminary action only for the major sources of aquifer pollution: DAPL and groundwater hot spot extraction and treatment. A final decision had yet to be made in this area.
With regard to soils and sediments, the latest actions were identified as cap-and-cover systems, excavation and recovery of soils and sediments, and institutional controls to protect against vapor ingress. The cost estimate was approximately $48 million.
Morash explained that Olin Chemical would have 60 days after issuing the negotiating letter to make a good faith offer to the EPA to perform or pay for the cleanup work. These negotiations would result in a consent decision and be followed by a corrective design process.
EPA project manager Josh Fontaine then provided background information on the temporary containment area limit they knew had been violated in November 2020. He said that at the time, Olin had been tasked with developing a replacement plan that would be more robust, for which construction would begin in late summer. They would improve the material, slope and safety of the cap to protect the containment area until the permanent cap is designed.
Hydrogeologist Chris Kelly elaborated on the goal of filling the data gaps to make a final decision on groundwater remediation. He said further research would be done on the geological features and groundwater and soil samples.
Phase 1a involves seismic reflection and refraction using ground radar, while phase 1b involves taking soil bores and water samples at locations to be determined. These were supposed to start this month.
At this point, the Wilmington Environmental Restoration Committee and the city manager were invited to respond. Suzanne Sullivan, vice president of WERC, expressed appreciation on behalf of WERC for the interim plan and the recent milestones made by the EPA.
“We remain frustrated with the progress in tackling groundwater contamination,” she continued.
Besides the length of the process, they were dissatisfied with the measures being taken to lower NDMA levels.
City manager Jeff Hull also shared his frustration at the time it took the EPA to fill the data gaps needed to complete the decision. He suggested that data collection and analysis and coordination of the design, location and size of extraction wells occur simultaneously. His concerns were with the future development of the Olin Chemical site.
Both Sullivan and Hull understood that the EPA’s interim action only involved lowering NDMA levels to 5,000 nanograms, or considering only the places with that exposure level. EPA Representative Lynne Jennings jumped in at this point to clarify that the 5,000 number was not a cleanup number.
“It’s just a starting point for us to focus on these areas.”
She also said she understood the issue over time and promised that they would aggressively go through the design process.
Jennings assured everyone in the audience that there would be future public information meetings with the final report of the decision for the final remediation areas.