Groundwater Sampling Devices
19
hook it and turn the gas cylinder on and off several times. We were constantly
getting mixed up initially and even after having lots of practice, we had to be
very careful not to get ahead of ourselves. In addition, this sampler was designed
to take large samples and thus was heavy and awkward to handle. Although we
didn't use a winch, we definitely recommend using one, especially for retrieving
samples from deeper wells.
We were able to watch the devices while they were being used in the stand-
pipe experiments. The PDB sampler caused only a slight disturbance when it was
lowered into place but then was left to equilibrate for several weeks. The Hydra-
Sleeve created bubbles as it went in and some during sampling but we found that
raising and lowering it slowly reduced this. With the Kabis Sampler, we observed
vigorous bubbling as it collected the sample. This appeared to disturb the water
above the sampler, and the device banged against the walls of the standpipe. In
contrast, the Discrete Interval Sampler and PneumoBailer did not appear to
disturb the water when they were lowered into the standpipe, and there was no
bubbling of the water column above the sampler as the sample was collected.
Table 1. Initial turbidity readings following sampling.
Kabis
Discrete Interval
Sample
HydraSleeve*
Sampler*
Sampler*
PneumoBailer*
number
1.1
6.7
6.2
3.9
1
7.6**
18.8
4.0
1.0
2
7.1
7.8
3.3
4.4
3
9.5
7.8
2.6
2.1
4
7.6
28.0
2.5
4.0
5
4.8
25.6
1.1
6
* The samplers were tested in the following order starting with HydraSleeve, Discrete
Interval Sampler, PneumoBailer, and Kabis Sampler.
** One of the samplers was lost in the well and had to be retrieved. The turbidity
remained elevated afterward.
In our field study, the HydraSleeve and Kabis Sampler elevated the turbidity
levels more than the other samplers did (Tables 1 and 2). We believe that the up-
and-down motion required to fill the HydraSleeve sampler was responsible for
elevating the turbidity with this device. We also noted that the bottom edges of
the HydraSleeve samplers were worn and one had a small leak in it. Because the
Kabis Sampler was almost the same size as our monitoring well, it behaved like
a piston pushing water in the well. We could hear and feel the water surging
around the device as it entered the water and hear it hit against the wall of the
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