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., 1.2 BACKGROUND A limited air sparging test was conducted on 8 September 2004 to gather preliminary .. information 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 and submitted under separate cover(ETIC 2004). Based on the favorable results of the initial air sparging test, and with the approval of the SJCEHD, injection point pairs IPI, IP2, and IP3 were installed in the source area as shown in Figure 2. Each injection point borehole was completed with two nested stainless steel injection points, one point for the potential injection of hydrogen peroxide (IPIA, IP2A, IMA) and one point for the potential injection of ozone (IP1B, IP2B, IM). The new 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 well installation report will be submitted under separate cover. r 2. PROPOSED SCOPE OF WORK As mentioned in Section 1, the following two tasks are proposed, as part of an evaluation to test the applicability of insitu oxidation as a remedial technology for the site: ` • Oxidant Injection Benchscale Study (performed in a laboratory) • Oxidant Injection Pilot Tests (pending results of the benchscale study and regulatory ` approval and permitting) The oxidant injection pilot tests will be performed only if the results of the benchscale study are favorable and indicate that oxidant injection can reduce hydrocarbon concentrations without degrading water quality at the site. 2.1 OXIDANT INJECTION BENCHSCALE STUDY An oxidant injection benchscale study is proposed to further assess the feasibility of injecting ozone and hydrogen peroxide at the site. During this test, measured quantities of ozone and hydrogen peroxide will be introduced into a measured quantity of soil collected from the specified site. This test will be conducted in a laboratory by PRIMA. The specific goals of this proposed benchscale testing are: • to estimate the ozone demand of soil; • to estimate the longevity of hydrogen peroxide in the presence of ozone; • to confirm removal of COCs and determine whether removal is due to volatilization or destruction; to measure the effect of peroxone, a mixture of ozone and hydrogen peroxide, on secondary water quality parameters including pH and metals, such as the generation of hexavalent chromium, [Cr(VI)]; and • if Cr(VI) or other metals are generated, to determine whether these metals can naturally attenuate by reduction to their initial state. This will be accomplished by introducing G Tmje is\73942WAMR\wP 120\w ,eX6.tl c 2