- Groundwater resources have become seriously threatened
due to improper use by industrial, municipal, and even public
sectors. Widespread contamination of aquifer systems has
jeopardized human health and the environment and methods for
restoring these systems are needed. Biological and chemical
in situ remediation, where contaminants are degraded within
the natural system, has become the foremost technique for
cleaning up affected sites. However, before in situ
remediation can be implemented, studies of the sites'
physical, chemical, and biological characteristics must be
Physical aquifer models (PAM's) were constructed for use
in evaluating groundwater remediation strategies in porous
media. The PAM's offer a unique approach for work of this
kind, the most important of which are opportunity for
conducting large-scale transport experiments under controlled
conditions, and maintaining geometric, dynamic, and reactive
similitude. The PAM's consist of aluminum reactors, 4.00 m
(length) x 2.00 m (width) x 0.20 m (height), supported by a
steel framework. Reservoirs at each end of the reactor
permit adjustment of hydraulic gradient across its length.
An array of 40 fully-penetrating wells allows versatility in
sampling, injection, or extraction of solutes. Experiments
can be performed under confined or unconfined, steady-state
or transient conditions where temperature, pressure, and
hydraulic gradient can be controlled.
Plumbing design, well design, sampling protocol, and
media-packing procedure were developed and tested in dye and
bromide tracer experiments. The results of dye experiments
in a water-filled PAM demonstrated the effectiveness of the
inlet and outlet port design and construction of the wells.
This was evident through control of a symmetrical plume that
developed within a uniform flow field. Protocols for
sampling, injection, and extraction using the well array were
also effective based on observed dye plume development and
bromide concentration contour plots. A new approach for
packing sand was used to create a statistically equivalent
homogeneous and isotropic porous media. Results of bromide
tracer experiments indicate that this condition of
homogeneity and isotropy was achieved.
The PAM's worked well for creating the desired
experimental conditions needed for studying transport of
solutes (non-reactive in this case) in porous media.
Additional experimental work will be done to develop and
expand more of their capabilities (e.g. transient flow,
confined conditions, heterogeneic media) for which they were
designed. Remediation strategies will be investigated using
the developed PAM's and it is hoped that results obtained
from these studies will be successfully applied to field