The New York State Department of Environmental Conservation has published a detailed sampling plan for the mercury-contaminated Superfund site at 55 Hillandale Road in Rye Brook, laying out where and how scientists will test soil, groundwater, air, sediment and surface water to map the full extent of contamination that has lingered for more than three decades.
The Village of Rye Brook posted the workplan on Tuesday, Aug. 11. The document, formally titled the Site Characterization Work Plan, was prepared by the NYSDEC and dated June 3.
The investigation is expected to take approximately 45 days and will use hand tools and drill rigs, according to a community message Mayor Jason Klein sent to residents on July 8.
The NYSDEC has not announced a start date.
The site, known formally as the Port Refinery Site, traces its contamination to an illicit mercury refinery operated at the property for roughly 20 years until the 1990s. The Westchester County Department of Health first notified the EPA of the mercury release on Feb. 20, 1991.
Thousands of tons removed, contamination persists
Two prior federal cleanups removed massive quantities of tainted soil. The EPA's first removal action from 1991 to 1996 hauled away more than 5,300 tons of contaminated material at a cost of roughly $6.4 million, according to the EPA's 2022 removal assessment report. A second remediation from 2004 to 2007, triggered when mercury was discovered near The Arbors condominium complex, removed over 9,300 tons and cost approximately $7 million.
But a June 2022 EPA sampling event found elevated mercury vapor readings in a neighboring property's basement sump, confirming contamination persists in the broader area beyond 55 Hillandale Road. The affected zone includes adjacent homes at 51 and 57 Hillandale Road, a common area of The Arbors, and sections of a storm drainage system with underground pipes, an open stream channel and four small ponds on properties downhill from the site.
Village pushes for transparency
Klein said in his July 8 message that the village first learned of the new state investigation on July 3, during a meeting with the NYSDEC originally scheduled to discuss access to village properties.
"It is concerning to the Village that it has taken so long for federal and state agencies to contact us with this information," Klein wrote.
He added that the village continues to push the NYSDEC and state Department of Health for complete transparency about the investigation and any remedial actions needed to ensure the area is safe. Klein credited the village's pressure with prompting the NYSDEC to issue a community update the same day.
The Rye Brook Village Board also moved quickly on its own monitoring. On July 6, the board approved a $35,025 contract with Omega Environmental Services of South Hackensack, N.J., for air monitoring at properties the village purchased through the Natural Resources Conservation Service.
What happens next
The NYSDEC stated that sampling locations may shift or expand as data comes in. If any location suggests the contamination boundary has not been fully mapped, additional sampling will follow. The agency has committed to sharing results and outlining next steps with the community once the data is in hand.
Residents can access project documents on the NYSDEC project page or contact project manager Michaela Cochran at (518) 402-9669.
