Groundwater remediation in residential areas surrounding BRAC sites



A full-scale iron permeable reactive barrier (PRB), composed of three segments, was constructed down to a depth of approximately 40 feet below ground surface (bgs) in an off-base residential area surrounding the former Kelly Air Force Base (AFB) in San Antonio, Texas. The PRB was designed to remediate trichloroethene (TCE)- and tetrachloroethene (PCE)-contaminated groundwater so the groundwater would meet drinking water standards. The PRB was constructed by azimuth controlled vertical hydraulic fracturing (ACVHF) technology in a residential neighborhood with numerous subsurface and overhead utilities. All sections of the PRB were constructed to the design specifications of approximately 3 inches in thickness from a depth of approximately 20 feet to a total depth of 40 feet bgs. The ACVHF method of construction was chosen due to the existing utilities, the requirement to minimize disturbance to the neighborhood, and the constraints of the worksite (residential two-lane road). This article describes the construction challenges and logistics that had to be managed to satisfy site-specific constraints for installing an in situ PRB within a residential neighborhood as part of the overall site remediation strategy for the former Kelly AFB. © 2005 Wiley Periodicals, Inc.