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k" K L E I N F E L D E R Equating molecular weights in the equation, 1 pound of 03 can produce approximately 2.1 pounds of the hydroxyl radical. The hydroxyl radical then oxidizes DCA as follows: C2C12H4+ 120H9 2CO2 + 8H2O + 2C1- Equating molecular weights in the equation, 1 pound of hydroxyl radical can oxidize approximately 0.37 pounds of DCA. In practice, contaminants exposed to ozone are typical oxidized by a combination of ozone and corresponding hydroxyl radicals. At a pH of 7 about 50% of the ozone transferred into water produces the hydroxyl radical. At low pH levels (3-6 range) the ozone is present primarily in the molecular form (03). At pH above about 10 the conversion of molecular ozone to the hydroxyl radical is virtually instantaneous. The hydroxyl radical is desirable because it is more reactive and slightly more persistent than ozone and is oftentimes responsible for oxidizing the stronger bonds in the compound. However, pound for pound it is a slightly less efficient oxidizer. Like oxygen delivery, the flowrate required is low and oftentimes soil vapor extraction is not required as part of the remediation strategy. j 3.2 PROPOSED PILOT TEST DURATION When properly implemented, air sparging is a historically proven technology for dissolved VOCs. The pilot test approach presented here assumes that if air bubbles are passed through the dissolved VOCs at the site they will be stripped to the vadose zone and removed. Furthermore, if oxygen is delivered by air sparging to dissolved, degradable TPH constituents they will biodegrade. These assumptions have been demonstrated in previous remediation work at the site and the attenuation behavior of the TPH phlme has been demonstrated in the groundwater monitoring reports. Considering these assumptions, the pilot test will not seek the objective of demonstrating the technology's ability to reduce dissolved contamination, but rather the / effectiveness of the proposed test design to generate desirable physical characteristics such as an J appropriate cone of air stripping and desirable oxygen delivery. Such an approach requires a much shorter test period and serves to expedite the overall remediation program for the site. In contrast to air sparging, ozone sparging is a relatively new technology and historical information of its effectiveness to remediate DCA is limited. Consequently, we are proposing to specifically evaluate the effectiveness of the technology,in oxidizing exclusively DCA. This will be done by measuring DCA in MW-DIS-1 after 4 days of ozone sparging as well as completing a nch scale test with groundwater from MW-DIS-11. We anticipate limited information from the field-scale results for MW-DIS-11 considering high concentrations of TPH are present in the vicinity that will likely interfere significantly with the effectiveness of ozone on the DCA. Furthermore, we do not anticipate that lengthening the ozone sparging period would improve the 1228012002R476 Page 9 of 26 Copyright 2002 Kleinfelder,Inc. May 17,2002