Former Lagoon Remediation
A former lagoon used for dumping, this site is riddled with contamination, as well as an extremely complex glacial lithology. Langan designed and implemented a unique air sparing remedial strategy to realize concentration reductions in the main contaminant of concern (COC), benzene, as high as four orders of magnitude in only the first year of operation. Extensive pre-design pilot testing activities, in-situ air stripping mass-transfer modeling, and two-dimensional (2D) subsurface pneumatic modeling were essential in the design of the required air sparging system and resulted in a number of site-specific innovations to the well-known air sparging technology. One of these innovations includes a high permeability 3-foot cap, which provided a media for effective vapor collection and artificially lowered the site water table to reduce the potential for water entrainment within the system. The use of a vapor barrier overtop this high permeability cap also ensured the effective capture of contaminated vapors generated from the air sparging activities and not ambient air.