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IEA WATER <br /> # - G R O U P 'J: C <br /> Iii,Situ..Res ration test_Pracedures 5 <br /> To qnti <br /> uafy the maxunum rate;at which oxygen delivered.to the vadose.zone canbe <br /> " metabolized "by.the :indigenous" organisms; a, selected: area is oxygenated Via a F <br /> vacuum, source attached to"a -well head The vacuum source will be:`either an <br /> ` internal combustion`engine:f(IC engine)`with attached biower ;ora V4 horsepower <br /> regenerative blower.: . The IC engine with•'attached,catalyticconverter treats-vapors <br /> prior` to emission. to-'the atmosphere. If a' regenerative. blower is used, on-site <br /> I ' electricity or a generator are used as a power..source.- Carbon canisters can be attached" <br /> E to 'the re erierative,blower to:treat va 'or-'emissions if necessary. <br /> g P rY <br /> Vhhen.oxygen :concentrations .m the extracted ,vapor and at. any' other monitoring <br /> ce of the.vacuum" reach neat..atmospheric concentrations <br /> points within the influen <br /> (15-20%), the . vacuum Is; turned. off and oxygen uptake and. carbon dioxide <br /> production qs monitored at;points.(wells) throughout'the'formation. At least one <br /> monitoring,point is 'located °in.uncontaminated soil" to monitor fluctuations in' <br /> .background oxygen,and carbon dioxide concentrations: The background "well :will ' <br /> not :necessarily be, 1'ocated` within the influence of: the "applied vacuum: " All <br /> monitoring]points should,4d"eally_beas'-�nairow as possible. However, common <br /> practice typically results in"- tests'.conducted'successfuliy in vapor extraction wells <br /> cohstructediwith 2-.to 4-in, diameter piping",(Downey, et al:, 1992; Dupont, 1993). , <br /> The initial oxygen and carbon dioxide`read"mgs:-will.be'collected after purging the <br /> well until: the readings are;;constant. . This generally takes a_few' minutes. Purging <br /> {u"•; <br /> wilt-be accomplished,using .an,.Alpha'!Orierair,sampling pum:,or equivalent:', 02' . <br /> 'ar d:.C62:readings will:.then.be`-collected.every twenty minutes`for the first. hour; <br /> every .alour, for the next' six.hours -and then.eyery fouir:to eight "hours until the 02 <br /> eoncentratioli.in 'the:soil gas,.;Yin: the ,con#aminated zone.'reaches '�5%-or tlie. initial <br /> depleted IeVels;,whichever is°higher Y= _ <br /> r Y <br /> g x F DATA.EVALUATION F f R <br /> Oxvgen Utilization Rates <br /> s s • �. r • } <br /> a " ' Data obtained during' the respiration! tes"t wilF'be. "used 'to determine ,"oxygen <br /> " utilization:rates. ` The oxy'gen utilization rate,;:is the mzaximuln rate at.-which"the <br /> ' indigenous;microorganisms,,.can use.oxygen to break down the hydrocarbons, •Any <br /> additional gxyge'n supplied'to"..the subsurface will not be.used':by the microbes. 'Based <br /> on,this "value; 'the-rr aximum air':flow rate"needed. for.,_bioventing.at •the'site can be <br /> t deierrriined:(discussed below) <br /> Tn'" itu Respiration Test Protocols " Page 3 of 6 �''s -Apel 28 1995 <br /> a� , <br />