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1.2 SUMMARY OF SITE-SPECIFIC ASSESSMENT EFFORTS FOR CHEMICAL OXIDATION Chemical oxidation can be an effective remedial technology for the oxidation of organic compounds in subsurface soils and groundwater Chemical oxidation using ozone and/or hydrogen peroxide generates the hydroxyl radical (OH-) to break down organic compounds into carbon dioxide and water The adsorbed and dissolved hydrocarbons present in a source area are susceptible via oxidation to breakdown through this process In addition to directly oxidizing organic compounds, the chemical oxidation system can enhance the aerobic bioremediation process by significantly enhancing dissolved oxygen concentrations in the vicinity of the injection points Increased dissolved oxygen concentrations should promote bioremediation within the surrounding hydrocarbon impacted soil and groundwater As with any in situ remedial technology, the ability to deliver the oxidants to impacted soil and/or groundwater is a key part of the success of this remedial technology The proposed injection of hydrogen peroxide and ozone to oxidize hydrocarbons at the site includes sparging ozone in the subsurface below groundwater As a preliminary assessment of the effects of sparging at the site, a limited air sparging test was conducted on 8 September 2004 Preliminary information was gathered concerning the extent to which a gas can be sparged through the subsurface The preliminary test was conducted using existing wells for air injection and observation The results of the initial test were favorable(ETIC 2004) Based on the favorable results of the initial air sparging test, and with the approval of the SJCEHD, injection point pairs IP1, IP2, and IP3 were installed in the source area as shown in Figure 1 for the potential injection of ozone and hydrogen peroxide Each injection point borehole was completed with two nested stainless steel injection points, one point for the potential injection of hydrogen peroxide (IP1A, IP2A, IP3A) and one point for the potential injection of ozone (IP1B, IP2B, IP3B) These wells were installed within finer-grained material to depths of up to 40 feet below ground surface (bgs) Well construction details are presented in Table 1 A laboratory benchscale study was designed and performed to assess the effect that hydrogen peroxide and ozone would have on both hydrocarbons as well as water quality Soil and groundwater samples collected during the installation of the injection point pairs, IPI-IP3, were used during this benchscale study Testing was conducted by PRIlVIA to evaluate and compare the ability of ozone (03) and peroxone (a mixture of ozone and hydrogen peroxide) to remove petroleum hydrocarbons from soil and groundwater at the site, to determine whether removal was due to volatilization (by sparging) or to destruction (via chemical oxidation), and assess the impact this technology would have on groundwater quality Comparing the effect of sparging with a chemically inert gas (nitrogen) to the effect of sparging with ozone provided data needed to distinguish volatilization of hydrocarbons from destruction of hydrocarbons The laboratory study clearly demonstrated that ozone and peroxone (a mixture of ozone and hydrogen peroxide) could destroy Total Petroleum Hydrocarbons as gasoline and as diesel (TPH-g and TPH-d) and benzene, toluene, ethylbenzene, and xylenes (BTEX) in soil and groundwater at this site The results of the benchscale study were presented in a Report of Findings Evaluation of Peroxone for the In Situ Chemical Oxidation of Petroleum Hydrocarbons (PFJAIA 2005) G 1Projects173942V lA5TER1WP\WP67fl51Omnc Injection Pilot Test Work Plan doe 2