EXPERIMENTAL
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All of the field samples used during the follow-
ing experiments were obtained from rectangular
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II
III
holes approximately 25 25 cm and extending to
depths between 20 and 46 cm below the ground
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6
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surface. At the site where the holes were excavated,
trichloroethylene (TCE) contamination has been
present for about 25 years. The soil at this location
(Hanover, N.H.) is characterized as a cohesive
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V
VI
silty-clay with an organic carbon content of less
than 0.5% (Hach method 8097), ranging in mois-
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ture from 13 to 16% (ASTM D2216-66).
Each experiment was performed as rapidly as
Figure 1. Sampling pattern for core liner experiments.
possible after exposing a smooth flat surface in the
Circles with crosses show location of samples taken exte-
native substrate. Except where noted, samples
rior to core liners.
taken for analysis were obtained and transferred
to VOA vials using 3-, 5-, or 10-cm3 plastic syringes
with their injection tip and rubber plunger-cap re-
and hammer were used to push each core liner to
moved. The open end of these corers were pushed
a 5.1-cm depth. These core liners were numbered
approximately 2.5 cm into the exposed surface,
IVI, denoting their position and orientation. Once
resulting in soil plugs of approximately 2, 4, and 6
positioned, 12 reference soil samples were taken
g. When transferring the soil sample, care was
in a pattern, so that four sampling locations sur-
taken to remove soil adhering to the exterior of
rounded each of the core liners (Fig. 1).
the corer before inserting it into the mouth of a
In the first experiment, samples were sequen-
tially collected by inserting a 5-cm3 syringe into
collection vial, so that the sealing surfaces would
not be compromised. The mass of the collected
the freshly exposed surface 1.2 cm, removing and
sample was obtained by the weight difference of
discarding the soil, followed by a second insertion
the collection vial before and after adding the
into the same sampling hole, 2.5 cm beyond the
sample. Samples collected with either the 3- or 5-
first insertion, and removing a plug of intact soil.
cm3 syringe were transferred to 22-mL auto sam-
This subsurface sample was immediately trans-
pler vial (Wheaton), containing either 10 or 15 mL
ferred to a VOA vial containing water. After all
of Type 1 water, and capped with a Teflon-faced
the reference samples (exterior to the core liners)
gray butyl septum and aluminum crimp top.
were taken, the core liners were removed from the
Samples obtained with the 10-cm3 syringe were
hole and, without covering, placed in a large plas-
transferred to 44-mL VOA vials (Eagle Picher) con-
tic bag. Each core liner was then sequentially sub-
taining 30 mL of Type 1 water and capped with a
sampled in the same manner, after periods of 1,
Teflon-faced silicone septum and plastic screw top.
10, 20, 30, 40 and 60 minutes (one sample/core
Soil samples, collected immediately after expos-
liner).
ing a fresh surface and transferred as described
The second experiment followed the same for-
above, served as the reference samples to which
mat as the first, except four of the core liners were
others were compared.
individually covered and stored. Once the samples
exterior to the core liners had been collected, the
Core liner experiments
core liner in the lower right-hand corner (VI) was
removed with the soil intact and sampled as de-
Field samples
scribed for the before-mentioned refer ence
In all, four separate field experiments were per-
samples. The next four core liners were then re-
formed using 3.6-cm-i.d. 5.1-cm brass core lin-
moved, one at time, going from right to left. Once
ers (Environmental Instruments). Uncovered in-
removed their exteriors and rims (top and bottom)
tact soils obtained in these core liners have an ex-
were wiped clean with a paper towel, both ends
posed surface area/sample mass ratio of approxi-
were then covered with either a single 7.6-cm-wide
mately 0.27 cm2/g. In each experiment, six core
sheet of TFE (Environmental Instruments) or
liners were inserted vertically into the bottom of
heavy duty aluminum foil, followed by press fit-
the hole, creating a 3 2 array. A wooden block
ting plastic end caps. The last core liner (I) was
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