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10 ( "%TC . A S S O C I A T E S I N C . ■ GHH Engineering Inc.'s Interim Groundwater Treatment System, Jamar Service, 4075 East Main, Stockton, California, dated October 2003. ■ ATC's Remediation System Installation Report for Jamar Property, 4075 East Main Street, Stockton, California dated 27 May 2003. ' KVA's C-Sparge System- Model 5030 Installation, Operation, and Safety Manual dated January 2004. The operation and monitoring of the C-SpargeTM system was conducted in accordance with these documents except where specifically noted herein. Remediation system field data is contained in Attachment 1. 4.1 C-SpargeTM Chemical Process Description MTBE and BTEX are the analytes of concern at the Jamar Property. In the C-SpargeTM process, air and 03 are injected directly into the saturated zone to extract dissolved BTEX and MTBE from contaminated groundwater. The system at the Jamar property has specially designed spargers to create "microbubbles" that have very high surface area-to-volume ratio. As the "microbubbles" rise within a saturated column of groundwater, they extract or "strip" the VOCs from the aqueous phase. Upon entering the microbubbles, MTBE and BTEX compounds react with 03 in the gaseous state or in the aqueous "thin layer" surrounding the bubble to decompose contaminants. Because of the high solubility of 03, over 10 times that of oxygen (CRC, 1972), the decomposed 03 leaves behind elevated dissolved oxygen. In general the rate of removal has been sensitive to 03 concentration, pressure, and iron silicate content although the iron silicate content is not a major concern at the Jamar property due to initial groundwater chemistry. The reaction rapidly detoxifies groundwater containing MTBE and BTEX compounds without producing harmful byproducts. Reduction of concentrations is extremely rapid.for benzene. The reaction is produced with very low 03 concentrations—molar ratios—compared to volatile organic compounds (VOC) concentrations in groundwater. The Henry's Constant which regulates the partitioning of MTBE from aqueous to gaseous state is about one-tenth that of benzene derivatives. However, according to the manufacturer of the C- Sparge system the surface-to-volume ratio increase of over 30-fold compensates to promote rapid in situ stripping of MTBE. 03 contained within the bubble and thin film around the bubble reacts extremely rapidly to decompose the MTBE into simple products: alcohols, acetate and formate. The residual oxygen from the reaction encourages bioremediation, which consumes the breakdown products and converts them to carbon dioxide (CO2) and water(H2O). In both bench- scale testing and field-testing; 03 microbubbles appeared effective in reducing MTBE - concentrations to beyond 90% of original levels (Kerfoot, 2000). C-SpargeTM (microbubble 03) 03 + 2H+ + 2e-_...> 02 +2142O SA268231QM reports12044 4QR.doc 5