An aerial view of Grumman corporate headquarters in Bethpage on...

An aerial view of Grumman corporate headquarters in Bethpage on Dec. 5, 1985. Credit: Newsday

Timeline of the plume

From the 1940s through 1998, the U.S. Navy and what is now Northrop Grumman operated manufacturing facilities on a 609-acre site in Bethpage. Here is a history of the contamination from the plant:

  • 1947: Hexavalent chromium, which has been linked to lung cancer, is found in groundwater south of the Grumman site.
  • June 1976: Trichloroethylene (TCE), a solvent and known carcinogen and liver toxin, are found in a private Grumman well at a level 100 times today’s drinking water standard.
  • 1986: Nassau County and the U.S. Geological Survey identify migrating contaminants as a plume, two miles long and one mile wide — a quarter of its present size.
  • 1998: Northrop Grumman begins pumping water through five extraction wells and treating it to remove volatile organic compounds, or VOCs.
  • 2009: A plume is found under Bethpage Community Park. Northrop Grumman begins operating a groundwater containment system in the park.
  • 2012: New York State Department of Environmental Conservation issues cleanup plan for the park plume.
  • 2014: TCE is discovered in groundwater at and near the Navy's former site. 
  • 2017: Navy agrees to pay $6.78 million for upgrades to a Bethpage Water District treatment plant. Gov. Andrew M. Cuomo says the state is prepared to spend $150 million to build a system of wells and treatment facilities to clean up the plume and stop it from spreading.
  • May 2018: Bethpage Water District announces plans to spend about $17 million to shut down three drinking water well sites that are drawing from tainted groundwater and drill new water-supply wells.
  • July 2018: More than 80 Bethpage residents or their estates file suit against Northrop Grumman alleging contaminants have led to medical injuries and death. The case is in federal court in the Eastern District of New York. 
  • January 2019: Construction begins on a $19.5 million water treatment facility for the Bethpage Water District.
  • March 2019: Bethpage Water District files federal lawsuit against Northrop Grumman and chemical companies over the likely carcinogen 1,4-dioxane.
  • May 2019: State DEC officials release a $585 million proposal to contain and treat the plume. Northrop Grumman and the Navy object to the plan.
  • June 2019: A state Department of Health report links groundwater pollution before 1976 in a well near the Grumman/Navy site to a higher risk of developmental effects in infants.
  • December 2019: State regulators approve the DEC’s $585 million plan.
  • September 2021: The state formalizes an agreement for Northrop Grumman to pay $60 million to the state and local water districts affected by the plume.
  • April 2022: In a consent judgment, Northrop Grumman and the Navy agree to pay Bethpage Water District $49 million to treat groundwater contamination.
  • July 2022: New York State finalizes a $104.4 million agreement with Northrop Grumman for the cleanup.
  • September 2023: The Town of Oyster Bay sues Northrop Grumman, alleging the company's cleanup of Bethpage Community Park has been “inconsistent and inadequate.”
  • April 2024: Contractors remove 10 drums buried beneath Bethpage Community Park. Six are found to contain waste petroleum and chlorinated solvents and testing is underway on the contents of the four other drums. Contractors also find a third underground concrete layer that state officials say could contain even more drums.

With research by Laura Mann

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