Directional Technologies, Inc.
Horizontal Biosparging for Expedited Remediation of Jet Fuel at DOD Sites
Horizontal biosparging remains a proven remedial technique to stimulate biodegradation of contaminates located beneath surface infrastructure or heavy traffic areas. This presentation will provide a brief overview of horizontal remediation well design and installation processes and discuss two case studies where horizontal biosparge wells were installed and operated to remediate jet fuel plumes at two Department of Defense installations. Site 1: Air Force Base in New York State: Soil and groundwater was impacted from at least two documented jet fuel releases and other site activities at the facility. The site is underlain by a complex geological formation providing a porous media for migration of petroleum LNAPL and dissolved jet fuel constituents in groundwater. To maximize oxygen distribution beneath areas difficult to access, horizontal biosparge wells were selected as the preferred remedial technique. In addition, installation of horizontal wells with directional drilling minimized disruption of DOD activities at the facility. A total of five horizontal biosparge wells with 200 feet to 300 feet of screen were installed with horizontal directional drilling methods at target depths ranging from 24 feet below land surface (bls) to 39 feet bls. Within three years of operating the horizontal biosparge system, groundwater sampling results indicated no volatile organic compound (VOC) concentrations above the regulatory groundwater standards. Site 2: Joint Air Force Base and International Airport in the Southeast: Based on the successful remediation of the DOD site in New York State, the DOD approved horizontal biosparging at a second facility in the Southeast. Unlike the site in New York State, this site was underlain by estuarine deposits with a shallow groundwater table. One of the target areas for remediation was located beneath an active tarmac and taxiway used by military and commercial aircraft. The target depth for the horizontal wells was 17 feet bls, slightly above a clay layer. Three horizontal biosparge wells, with 180 feet to 320 feet of well screen, were installed from entry points safely located approximately 80 feet from the active taxiway. During installation and operation of the horizontal wells, air traffic and base activities continued unimpeded, satisfying the requirements of the DOD.