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s 1 .0 INTRODUCTION Bench-scale treatability testing was conducted on soil (BT- 1 and BT-2) and groundwater (DPE- IS) from the 712 G Street site in Davis, California to evaluate the ability of hydrogen peroxide (with and without added acid or iron) to destroy gasoline range organic compounds (GRO) . 1.1 Background Hydrogen peroxide is a moderately strong oxidant that may react with some organic compounds. It is typically more effective when combined with iron, however. 11202and acidified ferrous iron (a mixture known as Fenton' s reagent), generates hydroxyl radicals, which are very reactive and can oxidize a wide range of organic compounds, including TPH-g. H2O2 can also react with dissolved (typically chelated) iron at neutral pH (often referred to as modified Fenton' s reagent) to generate other radicals, which also oxidize a wide range of compounds. The iron may be added along with theH202, or may be available naturally in soil or groundwater. Injection of H2O2 into the subsurface could enhance removal of GRO in several ways. For example, H2O2 could oxidize GRO directly; it could enhance aerobic biodegradation (11202 decomposes to generate oxygen gas), or it could react with available iron to generate radicals, which in turn would oxidize GRO. Addition of acid along with the 11202may facilitate reactions with available iron. Like all oxidants, the various H2O2 oxidant systems (11202, H2O2 plus acid, and H2O2 plus ferrous iron or chelated iron) may potentially have long term or short term secondary affects such as oxidation of soil-bound chromium to Cr(VI) or mobilization of metals due to a reduction in pH or to the presence of a chelating agent in the modified Fenton' s reagent. The magnitude of these potential secondary effects is site specific and generally also depends upon the concentration of H2O2 used. The ability of Cr(VI) (or other mobilizes metals) to naturally attenuate is also site specific, though metals mobilized due to chelation should attenuate once the chelating agent is destroyed. 11202decomposes to generate oxygen gas. At standard temperature and pressure one liter of I % H202generates about 6 L of oxygen gas, while 1L of 5% 11202generates about 30 L of gas. Thus, management of off-gases may be necessary depending upon the amount of H2O2 added and the rate at which it decomposes. 1 .2 Study Objectives Batch tests were conducted to evaluate various combinations of H2O2, acid and iron. Specific goals were to: identify the oxidant system(s) that most effectively destroy GRO determine the effect of each oxidant system on secondary water quality parameters PRIMA Environmental, Inc. 5 Eval of Peroxide February 8, 2007 Cambria—G Street, Davis