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d:
<br /> w..s v, �r e"s biode�r�dation at the sides sit tl tine '1 e.bae gxQ nd
<br /> f� 35
<br /> dissolved,oxygen concentrnf:iQji y es.frq2 to„3 mg/1
<br /> Al ;while,in the center of the lZl mex dived d ,ygerr ) elow
<br /> •,, ,the field detection limit(A r.49ane sp sin
<br /> width due to dispersion, oxy8c11reQntaili41ed:.
<br /> ground water mixes with B'1 }G_ t Pill,0,00q, "4w
<br /> ;
<br /> ing;biodegrpdation at the�luzanc sxd i';,
<br /> 0 25 r. ` r , A well cluster was installed along the Plipme centerline
<br /> c 560 ft downgradient from the.source in the B-B'section for. .:
<br /> W evaluation of the vertical disAutSon,of B'l'1✓X_ nd indica-
<br /> 2°
<br /> tor.' (Figure 6 and:Table 2). Dtrg OWSpdrt
<br /> `o downgradient,:the zone wrt>ri.tpeslugte�t) Vo�ppentra-
<br /> W m rr ;i t g); $ _z 1 tion appears tc'.siplc. ,thn.
<br /> In s�T h
<br /> y 13 8r.' e11► ? •:.
<br /> BTEX concentratrQrE ts,im medjately l�elovi t}l water table
<br /> is ' i ,while at sectiori,B B',the maitttpn.tgtal B'FEX rronceatra
<br /> ` tion ispresent in a well:screen 7,to 1�1't bej the a♦ r
<br /> 1 r� 3s table(well A19),.The vetcal9�}rQp,. long thea of:the
<br /> ;plume is due.to,surficial tec
<br /> . *400 .
<br /> adds a layer of-clea�n,:uneant tite uat 6"o+vtop..pf the
<br /> x400 , 400 ':i .'-x00rh794;jF o. raa... 1
<br /> plume and enhanres biodegraadattolrby ingo.ougng oxygen
<br /> ' with the;rechafge:water.,Ia1d141d $T13) , oast
<br /> 4 Ats and
<br /> 4 .
<br /> .Dlstatlo :fl'otn.:,A19'(feet)
<br /> indicator_paramete�r ec$iq
<br /> Ftig. 6.-Conto�rr4 bf -6tal BTEIf:(►A8/1)•in cross section B$'...
<br /> BTEX'Concentra... . n ttie shallowest well screen'{A9) have -,The carbon;dioxide;conconf&*.."is loVP,0 ;t jb*1-
<br /> dioei ased due torec ii[rgc of'clearlt oxy cnated'water. tom-screen-in the B-B'.sec00t0nd1*i�g,tllat+1p1 bio4W.a-
<br /> < datron;has occurred;at flit$t3 pth{.joluencd,o- yet�a
<br /> have,beeneffectively,romovfd.fqm*aentir4.doss;section
<br /> r ..whereas high concentrations.of;m= le.
<br /> g ►p^ y. ne, ethylben-
<br /> areas under the curves in;the tw`o,-Xoss sections should be" zene remain in the.center wells;•:l�erzzene is reduced i -wells
<br /> constant. However,'. over,this distance," areas-under,.the gbove and to the east and west sides of the plr but persists
<br /> toluene and'o- ylene;curves:drop by 90%and 98%j respec- at the center and bottom of the.plume The�r9n distribution 1
<br /> tiveiy;while ethylbenzene is'the ldesi'6ha4d(8%decline). is the,inverse of the benzene¢istributioi yvhere the highest
<br /> The,limited spreading of theplume is attributed to aerp�ic concentrations of dissolved_iron:arp.yeStiCall.y ove,at the
<br /> 'Table 2.Average.Copeentration of BTEX and Indicator Parim dirgin Crass'Sectidn•B-B"�;"�.
<br /> Location Mid-depth: . . Mid-depth Mid-depth Shallow Deep'
<br /> center west eaS1 ,,,-'Center center
<br /> Monitoring well: A19 A10 A11 A9 A8
<br /> Distance from centerline(ft): 0 -72 +68 0 0
<br /> Depth below mean water table(jt}:.. 7-12 7-12 7.12 2-7 17-22
<br /> B ruen'e(tegll). 628 42 88 167 656 I
<br /> Toluene(Reg/1) 80 .8 9 39 s' 41
<br /> Ethylbenzene(Rig/1) L,925 96 158 758
<br /> m-,p-Xylene(µ81l). 2,752 19$ 152 1,580 .:r.. 556
<br /> o-Xylene(u11/1)' 38 81 38 39. ::;:F:a,....:354
<br /> Total BTEX(Reg/1) 5,423 425 444 2,$98, 2,367
<br /> Methane(bng/1) 0.1 0.1 0.10,,1.. 0.1
<br /> COD(mg/'1) 21 g 11 ; 8 , _.: 30
<br /> Redox potential(mV) -118 -166 -161 =176 -217
<br /> Dissolved oxygen(mg/1) 0.2 0.4 0.4 0:5" :`=: ', i 0.5
<br /> Nitrate(mg/1 as N) '0.1 0.8 0.6 :0.9- 0.1
<br /> Dissolved iron(mg/1) 52 ..84 .86. 102 •6
<br /> Sulfate(mg/l as S) 1.3 1.7 1.3 0,3 3.3
<br /> Total sulfur(mg/I as S) , 2.3 2.3 2.7 1:7 12
<br /> Alkalinity(mg/l as CaCO3) 122 67 72 83' "2b i1
<br /> PH 6.1 6.4 6.4 '61;5 :5.5
<br /> Carbon dioxide(mg/l as C) 70 67 68' .57 57
<br /> Total dissolved solids(mg/1) 303 185 185 1,75 98
<br /> Temp(°C) 17.3 . 18.6 18.7 18.4 18.6
<br /> Calcium(rag/1) 7 7 6 10 S
<br /> :187
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