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zone, capillary fringe and upper portion of the saturated zone. Due to the presence of adsorbed contamination and the limited access to the subsurface, in-situ chemical oxidation can often be among the most cost effective remedial options. Disadvantages: The effectiveness of this technology is sometimes dependent upon permeability of the subsurface soils which are primarily clay-rich. Discussion: Based on this review of site conditions, including depth of impacted soil and groundwater with a significant dissolved phase concentration of TPHg and BTEX, in-situ hydrogen peroxide and/or sodium persulfate injection is considered a viable option for this site. The capability of remediating the hydrocarbons and treating the vadose, capillary fringe and upper saturated zones within a rapid time frame are particularly well suited to the existing conditions and requirements. Bench testing will provide detailed information regarding site-specific degradation rates. This technology involves the in-situ injection of chemical oxidants through 2 to 4-inch diameter wells or Geoprobe drill rods to treat the contaminants of concern in the source area. Through the application of ISCO technology, the material reduction of COCs in the groundwater will be achieved to the best achievable cleanup levels that is economically feasible. The best achievable cleanup level will be established through bench scale testing and pilot application and agreed upon with LARWQCB before application of the f1 full scale remediation effort. Based on previous case studies, reductions of TPH-g in soil and groundwater, BTEX compounds can be reduced from 25% to 75% with one injection event, however, specific site conditions and site variables will affect results. These variables affecting delivery of the treatment chemicals include the amount of total organic carbon (TOC), metals and other competing reactions that will consume the chemical oxidant, alkalinity, pH, and effective porosity. 7