Groundwater Sampling Devices
31
Table 9. Summary of results from field study (concentration TCE in mg/L).
Control
Discrete Interval Sampler
Mean
104
99.0
Std Dev.
2.15
4.16
% RSD
2.1
4.2
Control
Kabis Sampler
Mean
101
99.0
Std Dev.
0.98
7.7
% RSD
1.0
7.8
Control
PDB sampler
Mean
93.7
80.1
Std Dev.
0.84
0.62
% RSD
0.89
0.78
Control
HydraSleeve
Mean
103
92.0
Std Dev.
2.7
2.6
% RSD
2.6
2.8
Control
PneumoBailer
Mean
97.7
90.4
Std Dev.
2.07
13.9
% RSD
2.1
15
We also observed a small (5%) but statistically significant loss of TCE using
the Discrete Interval Sampler. In the previous VOC studies, we did not observe
any significant losses with this device although in the low-level study, the loss of
PCE was nearly 16%.
In contrast, the mean loss of TCE was 7.5% with the Kabis Sampler and
PneumoBailer, but these losses were not statistically significant. Our inability to
determine a significant difference in this case can be attributed to the larger
variability in sample concentrations that was observed with these devices.
Previously in the standpipe study, we observed a fairly large and statistically
significant loss of TCE with the Kabis Sampler. It is not surprising that there was
larger variability with this sampler given that we heard the device bang against
the wall of the well.
Previous Page
