After decades of cleanup efforts, the Navy opened a second groundwater treatment plant for the Bethpage plume on Tuesday.

It spent $46 million over five years building the Phase II Groundwater Treatment Plant at Union Avenue and Hicksville Road.

The Navy says it has six wells that will extract about three million gallons of groundwater per day from 750 feet below the surface.

Four of those wells are right above the most contaminated portion of the plume, dating back to Northrop Grumman operations from the 1940s.

They plan to build another complex just like it as the plume moves, which will be south of the Southern State Parkway.

That project is set to be completed in two more years.