The U.S. Army, in consultation with the U.S. Environmental Protection Agency (USEPA), and the Nebraska Department of Environmental Quality (NDEQ), issued a Record of Decision and Record of Decision Amendment (collectively ROD) for the former Cornhusker Army Ammunition Plant (CHAAP) which identified soil and groundwater contamination consisting of explosives above the USEPA Health Advisory Levels. The revised proposed plan for OU1 ROD Amendment identifies the Preferred Remedial Alternative for remediating groundwater at Operable Unit One (OU1) of CHAAP and provides the rational for the OU1 ROD Amendment. The preferred remedial alternatives include remedies for the on-post and off-post groundwater plume containing explosives. The on-post explosives plume will be treated to remedial action objectives using existing extraction and treatment technologies. The On-Post Plume Institutional Controls will include land use restrictions, enforcement of the Hall County Reuse Plan for agricultural and industrial zoning on CHAAP and prohibiting water supply well drilling in the plume area. The Health Advisory Level in effect as of March 1, 2001, is 2ug/1 (microgram per liter) or 2 ppb (parts per billion).
Pending natural attenuation obtaining the remedial action objectives of the ROD, the U.S. Army has requested that the City of Grand Island enact and enforce an ordinance instituting Off-Post Plume Institutional Controls by designating a groundwater control area in which groundwater use would be restricted to prevent human exposure and consumption of potentially contaminated groundwater, requiring registration of existing wells, prohibiting installation of new wells supplying water for human consumption in the plume area, and requiring approval and registration of new wells. The Institutional Control Ordinance is to remain in full force and effect until the explosive contamination identified in the ROD is attenuated to less than USEPA Health Advisory Levels.