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07410 uaI TeAnks I" Page 8 <br /> Dual Phase Extraction Pilot Test Report <br /> Project No 723 2 <br /> November 12,2004 <br /> events and then rebounded to 101,000 ug/l by June 11 After June 11 the TPH-G <br /> remained low, at less the half the initial concentration observed on March 19 These <br /> results are not unexpected since the hydrogen peroxide solution was introduced <br /> directly into this well <br /> o A routine quarterly groundwater monitoring event was conducted on August 25, 2004 <br /> and the TPH-G concentration in well MW-9 h4increased to 122,000 µg/l, which is <br /> near pre-injection levels <br /> ' Observation wells GP-1 through GP-3 displayed varying results <br /> o The well GP-1 TPH-G concentrations mirrored MW-9 as the graph in Figure 3 shows <br /> Since the wells are located approximately 12 inches apart these results are expected <br /> When the injection of the H2O2 solution into MW-9 was initiated on March 19, it was <br /> followed by a gaseous oxygen injection at 8 psi to force the H202 out of the well and <br /> into the formation After approximately three minutes a white, frothy, <br /> ' H202/groundwater solution erupted out the top of the GP-1 casing The oxygen <br /> injection pressure in MW-9 was reduced to stop the discharge from GP-1 The <br /> process of injecting the oxygen accompanied by the GP-1 eruption was repeated <br /> ' several times until a level below 7 5 psi was found to stop the emission from GP-1 <br /> On June 4, 2004, female PVC adaptors and associated threaded plugs were glued onto <br /> the GP-1 through GP-3 casings to allow greater injection pressures Wells GP-2 and <br /> G-3 did not experience the pressure breakthrough during the injection process <br /> o Well GP-2's TPH-G pre-test concentrations (199,000 µg/1) were higher than MW-9's <br /> ' (137,000 µg/1) In Figure 3 it can be seen that initial drop in TPH-G experienced in <br /> well MW-9 and GP-1 was not experienced by well GP-2 By April 4 the <br /> concentrations dropped followed by a rebound on April 28 A decrease followed the <br /> April 28 event and then a second rebound was recorded on June 25 <br /> o Well GP-3's TPH-G concentrations experienced an increase following the first <br /> injection event followed by two consecutive regressions After the April 28 injection <br /> ' the concentrations started a steady increase until the conclusion of the test The July 7 <br /> concentration of 143,000 µg/1 exceeded the pre-test concentration of 85,400 µg/l <br /> ' Ozone <br /> As stated in section 4 0 the introduction of ozone occurred during the last two injection <br /> events on June 11 and June 25 During these events groundwater samples were taken before <br /> ' ozone injection and approximately 3 hours later The groundwater data from MW-9 are <br /> summarized in the following table <br /> I' <br /> 1 <br />