Case Studies: Successful and Unsuccessful Redevelopment of Contaminated Sites - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 470

14.3 Case Study 2: Illinois
Case Study 2 is located in an urban area in Illinois (IEPA 2010). It is an idle brownfield site.
According to available records, it was first developed as a chrome plating facility in the
late 1960s and operated until 2003. Table 14.2 lists some basic information about the site.
The chemical primarily used at the facility was the heavy metal chromium VI. Secondary
chemicals used included mercury and lead. For cleaning, small amounts of solvents con-
sisting of an LNAPL mixture were used; however most of the cleaning conducted at this
facility consisted of a caustic dip tank and bath.
The facility was demolished after operations ceased. Demolition of the structure pro-
vided access to the subsurface for sampling, lower carrying cost, and reduced the potential
trespass liabilities. A Phase I ESA was conducted and identified five RECs, all associated
with the use and storage of chromium VI and LNAPL VOCs. Subsequent Phase II investi-
gations revealed concentrations of chromium that greatly exceeded the applicable regula-
tory criteria. In subsurface soil, there were very high concentrations (>10,000 ppm), and in
perched groundwater the levels were greater than 440 ppm.
To estimate the nature and extent of the contaminant mass, more than 75 soil borings
were drilled, over 20 shallow monitoring wells were installed, and nearly 500 samples
of soil and groundwater were collected and analyzed. The estimated mass of chromium
VI exceeded 13,000 lb. During the course of this extensive investigation, other contami-
nants were detected including LNAPL VOCs, lead, and mercury, but only chromium VI
required a remedial action. The majority of the releases originated from a concrete sump
and trench located inside the facility.
Figures 14.8 and 14.9 show the location of the site before and after it was demolished,
respectively.
Figure 14.10 shows a 3D cross section of the site and adjacent areas depicting the extent
of chromium VI impacts exceeding the applicable regulatory limit of 420 ppm. Figure 14.11
offers a different perspective of the extent of chromium VI and includes the locations of
the contaminant sources.
Inspection of the 3D maps shown in Figures 14.10 and 14.11 offers some insights into
the behavior of contaminants when they lack synergy with the geologic environment.
Although the site exhibited significant levels of chromium VI in soil, the vertical extent of

TABLE 14.2
Site Characteristics of Case Study 2

Characteristic Site Information

Location Illinois

Years of operation Approximately 35 years

Size of property Less than 2 ac

Geologic setting Lacustrine sediments

Soil type and stratigraphy Clay interbedded with some fine silt layers

Contaminants detected LNAPL VOCs, mercury, lead, and CrVI

COC CrVI

Depth to groundwater Groundwater present along building footings

Highest CRF GW ranking CrVI 2080

Highest CRF SOIL ranking CrVI 10.2

Geovulnerability ranking 13