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r h✓. - _ _ <br /> March 1991 <br /> Clint Rogers -��– —~` Page J <br /> Chevron U.S.A. Inc. <br /> 180, 1,2,700,and 120 ppmv,respectively. This decrease of vapor concentrttions indicates that <br /> the dispersed hydrocarbons are being drawn back to the focus of the plume. <br /> Figure 7 shows the hydrocarbon removal rate(lb/day)and the cumuiativ: mount of hydrocarbons <br /> removed as a function of the number of la's's in 4]b da operation. <br /> a minimum rate of 1hat the 1 lb/day and was last <br /> rate has declined <br /> from a maximum rate of 23 1 Y <br /> operating at a rate of 45 llonsy The total amount of hydrocarbons removed as of 26 February is <br /> 5,152 pounds,or 835 g <br /> action <br /> Lowering of the vapor concentration is agood indt�o`of <br /> hom ell can centrations alonethe arenotstrong <br /> ue to <br /> _y:tem is working, but decreases in vaporss transfer <br /> evidence that soil concentrations have decreased.onstemncould increase <br /> ive the same resw sstspa zetance d.If a <br /> drying of the soils or leaks in the vxtrac Y well <br /> evaluate the effectiveness of the system, the extractio a shift in compo$tion toward lessZvolatile <br /> decrease in vapor conn.?mtration is accompanied by =tration in the soils <br /> compounds,it is most likely; a change in 1 8 shows that ththe e percentages o compounds more volatile than <br /> (P.C.Johnson et al. 1990) Figuand that the re <br /> benzene in the extrae of <br /> cted soill vaoor hasdecrea ed fromfrom 14 ta high of 34�to the present of 16 <br /> toluene in the extracted sot p osition of the extracted vapors has <br /> percent. The two curves shown in Figure 8 show that the comp <br /> cates that the extra <br /> changed in composition d war le hy��ale co content pounds.of then soilsisbeing dec-eased ction sys4em <br /> is working effectively <br /> Additionally, Figure <br /> �8cuired or mOre <br /> within 5 significant ys and that arsimilar decrese of ase n the percentage oounds in the soil f toluene <br /> volatile than bene wells on the site,one of which will be located <br /> required 60. The installation of deeper monitoring <br /> of soil to be obtained that will be used to evaluate <br /> hear the source of the plume,will enable samples <br /> the progress of soil remediation to date. <br /> ' Th rm <br /> 10 , 1 r era i n•inti Desmtcti n Efficient Fuck & Associates MMC-5 <br /> The extracted vapors have thus far been abated using.a King, sam l <br /> 1tiMode Ccmbuster operating in the thermal Oxidati n a fluent • <br /> he opdiner has operatedes have been analyzed <br /> ll <br /> - <br /> during <br /> during the first 61 days of operation. To date a total �n constituents in <br /> Table 2 summaermal <br /> rizes the and calculated <br /> tion of la ed destructia efficietroleum ent es. Destruocarbl ction efficiencies are <br /> oxidizer effluent vapor To date the <br /> calculated on a volumetric basis using an estimat cnri ustionn(esttmaiad to,be.'small)�combustio <br /> chamber and neglet any volume change due to is 99. efficiency set by the <br /> average measured destruction <br /> effic <br /> uiency of s far has tbeen below oxidizer <br /> p r cent' percent. et y on <br /> destruction efficiency <br /> effic <br /> he range <br /> of 99.4 to 97.3 percent. No other destruction <br /> SJCAPCD. This was 94.8 percent measured on 5 Decembr Six other destruction her destruction <br /> were measured that day; all were in g <br /> efficiency has been measured during the course of operation thus far below 95 pe <br />