Table 4. Second field trial results
of rapid total VOC soil vapor
Table 3. First field trial results of
and collocated grab analyses. In
rapid total VOC soil vapor and col-
addition, values obtained for the
located grab analyses. In addition,
measurement of the site-specific
values obtained for the measurement
working standards and back-
of the site-specific working standards
ground are included.
and background are included.
Soil vapor
MeOH
Soil vapor
Aqueous
OVM PID*
HS/GC
Microtip PID*
HS/GC
(ppmv)
(mg TCE/kg)
Ratio†
(ppmv)
(mg TCE/kg)
65
9.31
32
0.765
42
180
11.4
1.8
0.0064
--
1600
1840
7.9
0.142
--
OR†
67.3
64
1.62
40
OR
1660
230
6.75
34
1200
51.6
1.8
0.0369
--
400
10.5
1.9
0.0518
--
140
1.06
34
1.28
27
140
7.81
42
1.65
25
1000
22.9
0.5
0.0239
--
1900
8560
0.2
0.0422
--
1900
15200
20
1.02
20
43
0.14
120
2.25
53
670
16
200
3.50
57
530**
5.9
590
11.9
50
39 13**
45**
0.66
23**
0.86
Response* (ppmv) of site-specific working
130**
1.2
TCE standards and background.
Response* (ppmv) of site specific
Working standard
Background
working standards and background.
8.2
0.6
Working standard
Background
8.0
0.3
8.3
0.0
6.4
0.0
6.0
0.0
6.6
0.0
7.4
0.0
6.9
0.0
5.2
0.0
* Model HL-2000 Photovac (Photovac
Inc.)
* Model 580B OVM (Thermo Envi-
† Ratio of soil vapor to grab sample con-
ronmental Instruments, Inc.).
centration, for locations where TCE was
† OR over range (>2000 ppmv).
>0.2 mg/kg.
** Samples taken from a fresh surface
** Mean and standard deviation.
within a rigid plastic core liner.
transferred to a plastic bag, thus often making it
the 0.2-mg TCE/kg decision marker were sam-
impossible to obtain reproducible collocated
pled. During the second field trial, all responses
samples, 2) residual product was intercepted,
were greater than the decision marker. Therefore,
which is heterogeneously distributed in a porous
during the second field trial, all of the grab sam-
medium, and 3) the response of the PID is not lin-
ples collected for the analysis were transferred
ear for the high concentrations associated with
directly to VOA vials containing MeOH.
residual product. The relationship for the first
The relationship between total VOC soil vapor
field trial is encouraging, since it indicates that
(in ppmv) and collocated grab samples (mg/kg)
concentrations over a range of at least 0.2 to 10
was both linear and significant, with a correlation
mg VOC/kg could be estimated using this rapid
coefficient of 0.982 for the first field trial. Indeed,
a fairly constant ratio (3913) existed between
soil vapor measurement technique, provided that
an adequate number (10 to 20%) of confirmation
these two analyses for the locations where TCE
samples were taken. It is probable that this range
concentrations were greater than 0.2 mg/kg
could be extended to higher concentrations using
(Table 3). This was not the case for the second
a field instrument equipped with a flame ioniza-
field trial because 1) many of the soils sampled
tion detector.
were highly disaggregated because of being
6
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