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JU1-02-99 15:28 From:URS GREIRER SF 4153981904 T-834 P 07/07 Job-859 — <br /> 18000 Pre-Injection concentration <br /> Post-injection concentration <br /> 12000 <br /> m M <br /> `o <br /> C <br /> 8000 <br /> x <br /> r c <br /> 5 4000 <br /> 0 IL <br /> 152 Q52 S48 S48 S48 S48 U20 W20 W20 W24 W28 <br /> (8) (10) (14) (16) (18) lel (10) <br /> Sample Location <br /> Figure 4: Pre-and post-injection analytical results from the Anniston Army Depot.Trichloroethene Is <br /> one of the major contaminants at the site. Only locations with pre-injection contaminant levels greater <br /> than 1000 ppm are shown. Post-injection results Indicate trichloroethene destruction ranging from 65 <br /> percent to 99 percent to date for the full-scale cleanup program. <br /> oxidation is DNAPL remediation. are limitations to in-situ chemical utilities. Very shallow <br /> Pump-and-treat and other oxidation.Free radical generation contamination of less than 2 in <br /> technologies often require years of by Fenton's reagent is favored below grade may not be effectively <br /> operation and maintenance and under weakly acidic conditions addressed,because the pressure <br /> may involve considerable onsite with pH levels of less than 7, generated may force injected <br /> construction.Furthermore,such which are achieved by Injection of fluids to short-circuit to the surface <br /> applications generally reach a a pH-buffered catalyst solution. rather than diffuse and disperse <br /> threshold,asymtotic level, Thus an important consideration is through the contaminated <br /> determined by contaminant the presence of carbonate soil formation.) <br /> sorption to soil panicles,pooling minerals or hard water conditions. write In 756 <br /> on the surface of impermeable Carbonate minerals react <br /> layers,vapor pressure and other vigorously with acids,resulting in The authors of 71iml Report for <br /> factors,below which cleanup higher reagent requirements and Demonstration of In Situ Oxidation <br /> becomes much less efficient. in many cases precluding of DNAPL Using the Geo-Cluanse <br /> On the other hand,asymtotic application to limestone aquifers Technology"(Savannah River site <br /> cleanup levels are not encountered or soils.Dissolved carbonate in case)are X.Jerome.8.Rlha and <br /> duringin-situ chemical oxidation water,existing 8.8.Looney o1 the Westinghouse <br /> g primarily as Savannah River Company,Alxen, <br /> cleanups in which the driving bicarbonate ion,also reacts with S.C. The authors of"Full-scale <br /> cleanup factor is delivery and acid and additionally is a free Remedistlon of Chlorinated <br /> contact of reagents with radical trap which also reduces Solvents in Clay Soils by In-Stfu <br /> contaminants.Thus,final oxidation efficiency.An additional Chemical axidatlon"(Annlaton <br /> treatment of sites which do not limitation is imposed by the heat Depot case)are R.S. Levin and E.M. <br /> achieve cleanup objectives is and pressure generated during Kellar of QST Environmental, <br /> achieved by installing additional subsurface injections of Fenton's Gainesville,Fla.;J. Wilson of Geo- <br /> injectom or injecting additional reagent. Cleanse International lne.:L. Were <br /> ants to enhance the deli of the Anniston Army Depot, <br /> reagents very. In-situ chemical oxidation may Anniston,Ala.;and J, Findley and J. <br /> not be suitable for free-product Ssehr of the U.S.Army Corps of <br /> �OOI�lU009�I W t744�QL plumes that are within active Engineers,Mobile,Ala. <br /> While a number of commercial underground storage tank fields or <br /> successes have been logged,there that surround underground <br /> Soil&Groundwater Cleanup August/September 1998 11 <br />