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Treatability Study Report and Feasibility Evaluation for In Situ Petroleum Hydrocarbon Remediation Field Maintenance Shop #24, 8020 South Airport Way Stockton. California concentrations, groundwater mounding, and pressure increases at the monitoring wells, the AS ZOI was estimated to be a radial distance of 20 to 30 feet. • Based on the evaluation of the above parameters, confinement of detected helium concentrations to a maximum distance of 34 feet from the test well, and the rapid dissipation of air pressure observed post AS testing: • Injected air was distributed efficiently within the subsurface; and • Injected air did not remain trapped within the subsurface. • Step testing conducted at the end of the FMS-AS1A and beginning of the FMS-AS1 B tests confirmed that air can be injected into the subsurface at reasonable flow rates and injection pressures. At the beginning of FMS-AS1 B testing, pressures between 34 and 47 psig produced air sparge flow rates between 7 and 22 scfm. After step testing, the sparging pressure stabilized at approximately 29 psig with a flow rate of approximately 20 scfm. • AS well spacing of 20 feet within the source area is recommended to provide adequate overlap of coverage. High Vacuum Dual -Phase Extraction Results Analyses of field and analytical data from HVDPE testing on wells FMS-DPE1 and FMS-MW5 confirmed that both vapor and groundwater can be extracted with the HVDPE technology. The following conclusions are presented for the HVDPE test conducted at wells FMS-MW5 and FMS-DPE1: Vacuum versus flow rate step testing conducted at wells FMS-MW5 (screened between 27.5 and 57.5 feet bgs) and FMS-DPE1 (screened between 20 and 60 feet bgs proved that the placement of well screens within the subsurface has a significant effect on performance. During the FMS-MW5 test, a vacuum of approximately 204 in. w.c. was required to draw vapor at 40 scfm while the well was dewatered. However, a vacuum of only 35 in. w.c. was required to extract soil vapor from well FMS-DPE1 at 53 scfm. • The soil vapor radius of influence for HVDPE was estimated at 100 feet based on the results of FMS-DPE1. • The groundwater radius of influence was not calculated because drawdown was not observed in the monitoring wells. • Vapor concentrations during FMS-MW5 and FMS-DPE1 testing decreased from 5,900 ppmv to 2,400 ppmv and 4,700 ppmv to 1,100 ppmv, respectively, over the course of testing. Concentrations are expected to further decline during continued HVDPE operations. • Water production during HVDPE testing ranged from approximately 0.8 gpm at well FMS-MW5 to approximately 2 gpm at well FMS-DPE1 maintaining maximum drawdown of 23.6 feet to 27.6 feet. • Vacuum enhanced aquifer parameters were calculated as: o Transmissivity: 11.3 gpd/ft at FMS-MW5 and 1.2 gpd/ft at FMS-DPE1 o Hydraulic Conductivity: 0.41 gpd/ft2 at FMS-MW5 and 1.2 gpd/ft2 at FMS-DPE1 OTIE iii