The U.S. Army Corps of Engineers (USACE), Louisville District, is nearing completion on the 23-acre landfill cap at the former Lockbourne Air Force Base, Columbus, Ohio.
The $12.6 million project, which is the largest single environmental construction contract ever awarded by the Louisville District, will be complete by spring 2015.
"Wastes from six excavation areas have now been located to a central consolidation area, and cover application should be completed in October 2014," said Cindy Ries, environmental engineer, USACE, Louisville District. "Final reports and inspection will extend into spring 2015."
During the summer of 2014 contractors worked on excavating additional waste and consolidating it to a smaller area, backfilling dirt, soil cover application and installing a leachate collection system.
The work is being performed by Cape Environmental, Inc., Norcross, Georgia, who is also working with Burgess and Niple, and Environmental Management Specialists, Inc., both of Columbus, Ohio, to complete the on-site work and groundwater sampling.
The property, which is now owned by the Columbus Regional Airport Authority, was previously owned by the government and used for waste disposal from 1951 to 1979, making it eligible for the Formerly Used Defense Sites (FUDS) program, which cleans up contamination on properties that were formerly owned, leased, possessed or used by the Defense Department.
Investigations showed the landfill was used for general trash from Air Force base housing and administrative buildings, construction and demolition debris and lime sludge from the base water treatment plant.
"A remedy was necessary and capping the landfill was chosen as the best way to effectively remediate the site," said Ries. "Capping the landfill will address potential risks to human health and the environment by preventing contact with contaminated soil and wastes. It will also eliminate runoff of chemicals to nearby surface water, and reduce leaching of chemicals from buried wastes to groundwater."
Capping the landfill involved first consolidating wastes into a smaller area so as to minimize the extent of the cap and cover maintenance. Next, a 24-inch compacted soil layer and six inches of topsoil create a barrier that prevents exposure to contaminants.
"In addition to the soil cover, passive gas vents, a perimeter seep prevention trench, and erosion and sediment controls, will be maintained as needed during the follow-on long-term management phase," said Ries.
After construction activities are complete the site will still have long-term management in place, which includes groundwater monitoring, inspections, and maintenance and an environmental covenant which will restrict future use of the landfill area to prevent exposure to onsite groundwater, intrusive activities and contact with waste.