NPL stands for National Priorities List and refers to the list of hazardous waste sites in the United States eligible for long-term remedial action (cleanup) financed under the federal Superfund program.
Active Non-NPL Superfund sites are places where site assessment, cleanup, or oversight activities are being planned or conducted under the Superfund/CERCLIS program. Afer this process, sites may get added to the National Priorities List (NPL).
Archived NPL/Non-NPL Superfund sites have already been assessed and are not included on the National Priorities List (NPL). This does not mean there are no hazards associated with a given site; it only means that based on available information, the location is not judged to be a potential NPL site.