Section One
SITE REMEDIATION
1    GROUNDWATER AND SOIL REMEDIATION
BY TREATING AND RECYCLING GROUNDWATER
Kostas Dovantzis, Environmental Engineer
Kurt O. Thomsen, Project Manager
Majid A. Chaudhry, Project Manager
Ronald R. Riesing, Group Leader
PRC Environmental Management, Inc.
Chicago, Illinois 60601
BACKGROUND
A refrigerator manufacturing facility is located on the lower end of two peninsulas formed by a
reverse "S" meander of a river (Figure 1). In the late 1960s, local regulatory agencies granted the
manufacturer permission to use the upper peninsula as a waste disposal area. Site contamination
resulted from the waste disposal activities.
Subsequently, a remedial investigation (Rl) was conducted at the site to determine the nature and
extent of contamination and to assess potential adverse effects to human health and the environment
that could be associated with the site contamination.
The RI was conducted in three phases. The first phase was the exploratory phase, during which six
well nests were installed. The results of this phase defined the general site stratigraphy. During the
second phase of the Rl, sampling was conducted to further define the site stratigraphy, hydrogeologic
units, and extent of contamination. Trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1,1-
trichtoroethane (TCA) were the major contaminants found in the groundwater. In addition, trace
levels (<15 /ig/L) of benzene, chloroform, 1,1-dichloroethane, 1,1-dichloroethylene, cis-1,2-
dichloroethylene, trans-1,2-dichloroethylene, methylene chloride, toluene, and 1,1,2-trichloroethane
were found in the groundwater. Trichloroethylene (TCE) was the contaminant found in highest
concentrations (as high as 35 mg/L) at the site.
Based on the results of the first and second phases, a consent judgment was negotiated between the
state and manufacturer to remedy the contamination. The consent judgment required that groundwater be treated until it consistently yielded a TCE concentration of no more than 15 /ig/L. TCE was
selected as the indicator parameter because, in most cases, its concentration in the groundwater was
an order of magnitude higher than either TCA or PCE. The 15 /ig/L TCE cleanup criterion was based
on the background concentration of TCE in the river adjacent to the site. The consent judgment also
provided that the system was to be operated annually from April through October. As a result of the
consent judgment, a third phase of the Rl was conducted to better define the stratigraphy of the
central portion of the site where most of the disposal activities took place (Figure 1). These data were
needed to initiate a feasibility study of possible remedial alternatives.
The results of Phase 3 indicated that the complexity of site stratigraphy is responsible for variable
groundwater movement at the site. Groundwater contamination is limited to an unconfined aquifer in
communication with the river adjacent to the site. Discontinuous lenses of aquitard/aquiclude materials are generally present at two levels within the aquifer (Figure 2). The groundwater contaminants are
mostly confined to the saturated zone above the upper aquitard with significantly lower amounts of
contaminants in the groundwater between the two aquitard/aquiclude layers. No contamination was
found between the lower aquitard/aquiclude layer and the confining layer underlying the aquifers.
Groundwater flows to the river (Figure 1) and vertically around and through the aquitard/aquiclude
layers present at the site. Vertical groundwater movement is upward to the river along the site
boundary. However, at other locations both upward and downward groundwater movement has been
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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