OU-1 Cleanup Progress
OU-1 was the main operating area of the plant and most of the contaminants were generated in this area. It consists of the main site area where gas manufacturing operations once took place (the primary source of contamination) and properties immediately to the east, west and south.
Cleanup of the most significant, central portion of OU-1 where gas making operations took place has been largely complete for several years. The cleanup included the excavation of contaminated soils, installation of a subsurface barrier wall to stop further migration of coal tar, and operation of an ozone treatment system to destroy the highly concentrated groundwater contamination found in this area. Treated groundwater which passes through the subsurface barrier wall and leaves this area is free of site-related contaminants. This ozone system is functioning well and is designed to continue operating indefinitely into the future. In February 2013, an additional recovery well was installed inside of the barrier wall to increase the physical removal of coal tar from the subsurface.
Outside the core area of OU-1, National Grid has completed investigations on properties immediately to the east and west of the former MGP site, and is preparing a cleanup plan to address the groundwater impacts identified. In October 2012, National Grid removed shallow soil contamination from beneath the Long Island Railroad crossing of North Clinton Avenue, in conjunction with a planned upgrade of the crossing.
