This study demonstrated the use of permeability enhancement technology (i.e., environmental fracturing) to facilitate enhanced amendment delivery and distribution in low-permeability materials. The overall objective of this project is to compare the performance and cost benefits of hydraulic and hybrid pneumatic permeability enhancement for in situ treatment at low permeability sites. The technology demonstration was performed at three separate sites with low-permeability lithologies including the Marines Corps Base - Camp Pendleton (MCB-CP) Site 1115 located in Oceanside, California; the Lake City Army Ammunition Plant (LCAAP) Site 17D located in Independence, Missouri; and the Grand Forks Air Force Base (GFAFB) site TU504 located in Grand Forks, North Dakota. The hydraulic approach to permeability enhancement was performed at all three aforementioned sites. In addition, hybrid pneumatic permeability enhancement was performed at LCAAP to provide a direct comparison between the hydraulic and the hybrid pneumatic approach to permeability enhancement. Advanced geophysics monitoring tools including tilt meter monitoring, electrical conductivity logging (EC logging), and electrical resistivity tomography (ERT) were used to evaluate the vertical and horizontal extent of amendment distribution resulting from permeability enhancement, and conventional soil confirmation and groundwater performance monitoring were used to validate the geophysics monitoring tools.