the VOC studies, the test solution initially con-
did not aid in the removal of the VOCs from the
tained ~2 mg/L each of m-nitrotoluene (MNT),
more sorptive PTFE surfaces. While solvent rins-
TCE, p-dichlorobenzene (PDCB), and tetrachlo-
ing did slightly improve removal of the pesticides
roethylene (perchloroethylene or PCE). In the
from LDPE tubing, oven drying was much more
pesticides studies, three additional polymeric
effective. We (Parker and Ranney 1997b) con-
tubing materials were also tested: low-density
cluded that a considerably cumbersome, expen-
polyethylene (LDPE), polyvinylidene fluoride
sive, and hazardous step (i.e., solvent rinsing)
(PVDF), and a copolymer of vinylidene fluo-
serves no useful purpose and thus could be elimi-
ride and hexafluoropropylene [P(VDF-HFP)].
nated from all decontamination protocols.
Initial concentrations of the pesticides ranged
from 576-5605 g/L for lindane, from 0 to 96
g/L for heptachlor, from 160 to 625 g/L for
PURPOSE OF THIS STUDY
aldrin, and from 191 to 393 g/L for dieldrin.
Generally exposure times for sorption and des-
The purpose of this phase of this study was to
orption were 10 minutes/10 minutes, 24 hours/
test various decontamination procedures on
10 minutes, and 24 hours/24 hours.
groundwater sampling devices that have been
We found that all the organic contaminants
exposed to a variety of organic contaminants. Pro-
tested could be readily removed from the
tocols that used hot detergent washes and hot air
nonpermeable stainless steel surfaces with a hot
drying were used in these studies because of our
detergent wash and hot water rinse. However, as
previous findings. Presumably, sampling devices
expected, the permeable polymeric materials were
will be harder to decontaminate than the small
much less readily decontaminated. Ease of de-
test pieces of the various materials that were used
contamination was a function of the analyte, the
in the previous study. This is because sampling
rigidity or sorptive nature of the polymer, and the
devices are larger and more complex in structure
contact time.
and, in some instances, may be fabricated with
Detergent washing and rinsing with cold wa-
several types of materials.
ter was not effective for removing VOCs from the
more sorptive PTFE test pieces, or from the rigid
PVC test pieces that had been exposed to the test
MATERIALS AND METHODS
solution for the longer sorption/desorption re-
gime. However, VOCs were readily removed from
General information
the PVC test pieces by washing with a hot deter-
Two groundwater sampling devices were used
gent solution and rinsing with hot water. For the
in this study: a dual-check valve bailer and a
more sorptive PTFE, additional oven drying
bladder pump. These devices were used to sample
(105C) was necessary for effective decontamina-
water that contained either TCE, a mixture of
tion. Apparently oven drying speeds diffusion of
various munitions, or a mixture of pesticides. TCE-
the VOCs out of the polymer.
contaminated groundwater was obtained by sam-
Pesticides were readily removed from most of
pling two monitoring wells that are located on
the polymeric materials by using a hot detergent
our laboratory grounds. Water contaminated with
wash and hot water rinse. (A cold detergent wash
pesticides and munitions was sampled by filling
procedure was not tested.) LDPE was the excep-
a large standpipe with one of these solutions.
tion to this, and could not be adequately cleaned
The bailer was contaminated by lowering it
using this method if the exposure times were
into the well or standpipe and then recovering a
longer (24 hr/24 hr). Detergent washing followed
sample. For samples taken from the standpipe,
by oven drying substantially improved removal
the bailer was allowed to sit in the standpipe for
of these contaminants (by a factor of 10), with
two minutes before the sample was retrieved. This
only low-g/L concentrations of one pesticide
was done to simulate the time it took to sample
still detected. LDPE tubing was the most sorptive
our deeper well. To contaminate the bladder
of the tubing materials tested and absorption
pump, it was lowered into the well or standpipe,
within the polymer matrix appears to be quite
and ten system (pump and tubing) volumes were
significant. Again it appears that oven drying
pumped through the system. In the case of the
speeds diffusion of the sorbed organic chemicals
standpipe, the test solution was recirculated by
out of the polymer.
pumping it back into the standpipe. After pump-
This study also showed that solvent rinsing
ing the ten pump volumes through the system, a
4
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