Taming the “Tower Plume”
At the former Reese AFB, a unique collaboration between industry and the Air Force has helped remediate groundwater contamination that was once contaminated 1,000 times the allowable level.
By Rachel Zaney
From the original 800-acres of groundwater contamination in 2004, (top) today less than 1-acre remains at the former Reese AFB, near Lubbock, Texas (bottom). A performance-based remediation contract was instrumental in saving the Air Force more than $20 million.
PHOTOS COURTESY ARCADIS
It was once called the “Tower Plume,” a 3-mi underground stretch of environmental contamination at the former Reese Air Force Base, near Lubbock, Texas. Decades of cleaning solvent use while repairing airplanes at the base resulted in groundwater contamination 1,000 times the allowable level. Original cleanup plans estimated it could take 60 years to 70 years of ongoing remediation before the plume could be cleaned to regulatory standards.
Through a unique partnership with private industry, the U.S. Air Force has, in less than 10 years, dramatically reduced the plume by more than 99 percent— taking it from worst-case environmental issue to a base cleanup best practice.
All parties either involved or affected by the remediation (including the Air Force, regulators, remediation contractor, local residents and community leaders) realized the need to work collaboratively. They developed a positive working relationship, the value of which has been demonstrated by the results.
IDENTIFYING A PROBLEM
Reese AFB had a flying training mission until its closure in 1997 under the Base Realignment and Closure Act (BRAC). The base had been recommended for closure in 1991, but significant environmental issues stood in the way of property transfer. Impacts included petroleum products and chlorinated solvents in soil and groundwater, with one of the solvent plumes extending more than 2-mi off base, impacting more than two dozen residential water systems.
As mandated by BRAC, the Air Force Real Property Agency and the Air Force Center for Engineering and the Environment were responsible for cleaning up past contamination at the site. They recognized that by relying on the expertise of private industry, contaminated sites could be cleaned and returned to the local community faster. As of October 2012, both agencies, along with the Air Force Civil Engineer Support Agency, have merged into the Air Force Civil Engineer Center, a field operating agency subordinate to the Air Force Civil Engineer, which will carry on the mission oversight.
FIRST PBR CONTRACT
In 2004, the Air Force awarded the first performance-based remediation (PBR) contract to ARCADIS. PBR contracts have proven to pave the way for creative and innovative technologies that clean up environmental contamination at former installations faster. They allow for more site closures than originally planned because they require performance-based endpoints. This gives both the Air Force and the contractor flexibility in revising remedial approaches where needed without having to modify the contract— reducing potential delays and saving money. At Reese alone, the savings was some $22 million.
PBR contracts are unique because they allow partnering that utilizes best practices and creativity to complete environmental cleanup. In other words, the Air Force identifies the desired end results, and the private industry contractor proposes how it will best achieve the prescribed goals in the quickest, most cost-effective manner.
PBR contracts have been so successful that Terry Yonkers, Assistant Secretary of the Air Force for Installations, Environment and Logistics, implemented aggressive cleanup goals for installations closed under BRAC. The goal is to have 95 percent of all sites under a PBR contract by 2014 and complete clean up at a minimum of 75 percent of all contaminated sites by 2015.
The Reese contract was ahead of the curve. The partnership created between the Air Force, ARCADIS, Lubbock Reese Redevelopment Authority, the U.S. Environmental Protection Agency, and the Texas Commission on Environmental Quality was done so with one goal in mind: to clean up the land faster so the community could benefit. The health and safety of residents were always top priorities. Furthermore, contractors were careful to minimize any interruption to businesses at or involved in activities at the base.
The contractor utilized this “pump and treat” system to remove water from the contaminated site, treat it, and return it to the area for reuse. The plume at Reese AFB has been reduced by 99 percent since 2004.
Using an innovative approach called remediation hydraulics, ARCADIS developed a 3D computer model to better understand the groundwater flow and to identify what technology would work best in cleaning it up. The results justified the use of “enhanced in-situ biodegradation.” This process, whereby a non-toxic compound (in this case it was molasses) is introduced into the groundwater, stimulates naturally occurring bacteria to consume the contaminant. The end result is a carbon dioxide and chloride byproduct.
Coupled with an innovative directed groundwater recirculation system, a “pump and treat” technology was used to decrease the size of the plume. The contractor pumped water from the contaminated site, sent it to an air stripper and activated carbon system to volatilize and remove the contaminants. The water then was returned to the area for reuse.
The treated water has the added advantage of having elevated dissolved oxygen levels, which helps restore those portions of the aquifer that have undergone reductive dechlorination. The groundwater was continually analytically tested to determine the effectiveness of this approach; the results were used to adjust the extraction and injection patterns on at least a quarterly basis to target the plume reduction. This method identified areas of the aquifer that exhibited the highest flow characteristics in the aquifer, which corresponded to the primary path for contaminant migration. ARCADIS used this previously unidentified pathway to guide on-going remedial efforts.
As a result of this technology, the Tower Plume has been shrinking by 2-acres to 3-acres a week since 2006. The contractor coordinated this approach with the Air Force, regulators and the public so that local residents can use the aquifer as a drinking water and agricultural irrigation source while the remediation continued.
A MODEL TO FOLLOW
From the original 800-acres of contaminated groundwater, today less than 1-acre of contamination remains. Environmental regulators require three annual clean sample results before the Air Force can officially complete remediation of the plume at Reese, which is scheduled for 2014.
The partnership at Reese exemplifies how a PBR contract can help pave the way toward achieving cleanup goals ahead of schedule. And the rest of the Air Force is following suit. The service currently has 18 contracts covering 29 installations under PBR contracts.
The introduction of PBR contracts played an important role in the success of cleaning up Reese AFB. But it was not the only factor. The cleanup would not be where it is without the hard work from the Air Force, private industry, state and federal regulators, members of the community, and the Lubbock Reese Redevelopment Authority. This collaboration, in synch with the environmental innovations and the PBR contract, are what helped tame the “Tower Plume,” and make the project a model for environmental success.