LEVITTOWN - Rising levels of a potentially dangerous chemical around Levittown have prompted the U.S. Navy to plan for a new water treatment facility on Long Island. John Caruso, commissioner of the Massapequa Water District, says he's been worried about an underground plume of an industrial solvent called trichlorethene for more than a decade. Officials say the plume originated at the old Grumman facility in Bethpage and has been seeping further south for years. The plume has now reached the area around a Levittown site once owned by the U.S. Navy. Officials say the Navy is taking action by building a water treatment plant to prevent the solvent from reaching people's drinking water. Navy officials say a temporary plant will be built in Levittown in April and a more permanent plant will be up and running next spring.