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<br /> 15Noyember,1.999.
<br /> ,,AGE-NC.Project No. 95-01-06
<br />�. Page 3 of 4
<br /> µg/l toluene,'and 9.5 1.zg/l and 89�ig/l ethylbenzene and 20 I�Lg/1 aild'89�ug/1 xyleries in'samples'frorn ;
<br /> . MWA•and-MW-4, respectively. Other analytes were'not,detected in,the two samples-..
<br /> 5 ,
<br /> '} Neitb&TPH=g•nor 13TEX.corripouhds were;detected in the:ground-water.samples ifrommohitoring
<br /> I : wells MW=2,MW'3,MW-5;MW-6'(upper)or MW-6(lower)and MW-7. Oxygenated fuel additives
<br /> were not detected in any of the grouri&water samples: Analytical results'of ground water.samples
<br /> for'the August 1999 monitoring event are summarized.-on Tables 2, and 3. The;laboratory report
<br /> ' . .
<br /> (MAI Laboratory,ID 1801 l through 18018),,QA/Q C-andchain-of-custody are included in Appendix
<br /> B
<br /> 4.0-- "SUMMARWCONCLUSIONS
<br /> THe'followin conclusions Were drawn froni'the results of the site,investigation t
<br /> The ground'water,gradient,on 24 August1999 was calculated to range'from 0.014 toward the
<br /> northwest to 0.014 toward the northeast.
<br /> Ground water elevation at the site an average of 1-0 foot since the'last quarterly,
<br /> monitoring event. ,
<br /> • Dissolved petroleum hydrocarbons were detected in'ground',watet samples•from'monitoring
<br />' wells MW-1 and MW-4;-Iocated cross to down-gradient.on-site and down-gradient off-site,
<br /> respectively, from the'former US T,excavation.
<br /> • Oxygenated compounds were�not'detected in any,of the groundwater:samples.,bY:EPA
<br />' Method'8260-Modified
<br /> • BTEXcompounds were detected Fn`the water samples collected from MW4-and-MW-4,the
<br /> concentrations-of benzene-exceeded the State of California maximum.contaminant-level '
<br /> (MCL} of 1 �g/l'for drinking-water
<br /> • , ... ' .n ' r. q n r • ,.
<br /> • ' As can be seen on Table 2, the`concentrations.of analytes detected in the ground water,
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<br /> course f the`six.previous sam lin %momto nW eluents but have generall deellned,oyer the
<br /> samples from the impacted on-site monito y
<br /> ours o p; op g g e rebounded during the first
<br /> three,quarters of 1999: ,. . .
<br /> ArialyticaLdata from monitoring well MW,2 limits.the extent of dissolved hydrocarbons
<br /> - .i • ,sou,. - _ ,r - �
<br /> t r thward•.of-the site.,'A;. nalytical data.from well:MW-3 ;and MW 6 limits the extent of
<br /> dissolved hyd'bca:r`bons northeastward7ofthe site.Analytical'data froiri monitoring well MViW- ,
<br /> 5(limits the.extent of dissolved hydrbcaiboris- westward.of the srte: 'Analytical-data from well, ',
<br /> 1 - •1
<br /> MW-7 limits the extent of dissolved hydrocarbons east of.the site.,
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<br /> Advanced GeoEnviron meniai,Inc.
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