Nebraska City, NE: Former Lincoln Air Force Base, Atlas “F” Missile Site 4

Formerly Used Defense Sites (FUDS) Program

Published April 7, 2015

Location and Description: The former Lincoln Air Force Base Atlas Missile Site 4 is located four miles west of Nebraska City in Otoe County, NE (just west of the interchange for Nebraska Highways 2 and 75). The site occupies approximately 23 acres and was one of 12 missile sites surrounding the former Lincoln Air Force Base. Construction of the Atlas missile site occurred in 1961 and 1962. Site facilities consisted of: an underground reinforced-concrete missile silo, connecting underground launch control center, two underground storage tanks for diesel fuel, two groundwater production wells, water treatment plant, four USTs for water, plus an underground fuel catchment tank.

The former Lincoln Air Force Base Atlas Missile Site 4 facility also included: a cooling tower, septic tank with a subsurface sand filter, water treatment holding pond, incineration pad, concrete headwall, and two corrugatedsteel igloos. The site was operational from 1962 through 1965 and was decommissioned and transferred to private ownership in 1967.

Problems and Response: Soil samples collected in 1989 and 1992 contained very low levels of trichloroethene (TCE) and 1,2-DCE, which were the only volatile organic compound contaminants (VOCs) detected in the two soil borings. In 1996, soil contamination did not exceed U.S. Environmental Protection Agency Region 3 residential risk-based constituent benchmarks, presenting no excess risk to site receptors.

However, groundwater detections above the benchmarks present a limited but excess risk to residential receptors. In 2010, fieldwork was attempted to delineate the extent of groundwater contamination, but was interrupted by record rainfall making access extremely difficult. Fieldwork was delayed until 2011. Shallow groundwater wells were installed during 2012 that adequately delineated the nature and extent of the shallow groundwater zone. However, several deeper wells were installed to determine if contamination had spread to the deeper groundwater zone. Several deeper wells showed the presence of VOCs above regulatory levels.

Activities for 2015: The U.S. Army Corps of Engineers will continue working on the remedial investigation/feasibility study. The Omaha District completed the final remedial investigation in September of 2012. Omaha contracted out the feasibility study in 2013.

Proposed Activities for 2016: Complete the feasibility study along with a draft proposed plan.

Issues and Other Information: It may be difficult to remediate groundwater because the site has been altered due to highway construction (Nebraska Route 2) and landowner modifications. Delineation of the deep groundwater zone has been difficult due to site conditions. Special care has to be taken to ensure that installed wells do not contribute to connectivity between the deep and shallow aquifer. Very tight clay formations have made drilling difficult in the deep aquifer.