Groundwater Sampling Devices
5
device was moderately tricky to operate during the retrieval and preservation
steps. In fact, we noted that the manufacturer recommends an hour of training.
HydraSleeve
The HydraSleeve is a cylindrical, flexible polyethylene bag with a polyethyl-
ene check ball at the top (Fig. 2). It is suspended from a line, is held together with
stainless clamps, and has either a stainless steel or PVC weight attached to the
bottom to keep it at the proper depth in the well. Currently, 350-mL-, 1-L- and
1.5-L-sized samplers are available, but other sizes can be readily manufactured.
The 350-mL sampler is 1 foot in length and approximately 1.8 inches in diameter
when full. The 1-L sampler is approximately 3 feet in length with the same out-
side diameter. This device reportedly allows discrete depth sampling of all types
of analytes (VOCs, semi-volatile organics, metals, etc.) and is designed to be a
no-purge system. The manufacturer's instructions recommend that the sampler be
placed in the well and allowed to equilibrate for 24 hours prior to sampling. This
equilibration time would allow for the well to return to its native state, air to vent
from the sampler, and equilibration between the plastic bag and analytes in the
well (i.e., sorption/desorption). The device is then raised and lowered approxi-
mately six inches twenty times to collect the sample. During the upstroke, the
upper check valve opens and water moves into the flexible chamber, expanding
it until it has filled. During the down cycle, the check ball seals. According to the
manufacturer, once the bag is full, the internal pressure and floating ball keep the
check valve closed as the device is recovered from the well.
The manufacturer claims that costs are reduced because the device is easy to
operate; this reduces sampling time, especially if purging is eliminated. The
device is relatively inexpensive, per sampler depending upon size, and
this cost can be reduced by reusing the device in the same well.
To date, we have not found any published studies where the HydraSleeve has
been evaluated.
Discrete Interval Sampler
The Discrete Interval Sampler and the PneumoBailer both utilize positive
pressure while the sampler is being lowered and raised to achieve discrete level
sampling. According to the manufacturers, this prevents loss of VOCs during
retrieval and prevents contamination from other layers during deployment and
retrieval.
Previous Page
