Case Studies: Successful and Unsuccessful Redevelopment of Contaminated Sites - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 473

was very economical and became the primary remedial technology. Soils with lower con-
taminant concentrations were treated with an application of ferrous sulfate—a chemical
reactant—to immobilize and change the valance state of the chromium VI to chromium
III. Chromium III is much less soluble in water, is not nearly as mobile as chromium VI, is
not a recognized carcinogen, and is much less damaging to plants and animals.
The lessons learned from this case study include

• Geologic maps are essential to all remediation efforts. In areas where there are no
synergistic effects between the geologic environment and chemicals with high
contaminant risk factors, geologic maps can help reduce monitoring well-drilling
costs.
• Low points in and around buildings can act as conduits of contamination.
• Anthropogenic disturbance (i.e., backfilling building foundations and footings
with porous materials) can enhance contaminant migration.
• Three-dimensional maps depict the extent of contamination in an easy-to-under-
stand and communicable format.
• This site is underlain by thick lacustrine clay. The low vertical extent of large
amounts of the highly mobile chromium VI suggests there is limited migration
potential in this geologic environment.
• There can be successful and cost-effective remediation when contamination occurs
in a favorable geological setting.

14.4 Case Study 3: Indiana
Case Study 3 is located in an urban area in Indiana (IDEM 2005). It became a brownfield
site when it was shut down after more than 100 years of operation. According to available
records, it was first developed as a foundry in the late 1800s. Table 14.3 lists some basic
information concerning the site.

TABLE 14.3
Site Characteristics of Case Study 3 Located in Indiana

Characteristic Site Information

Location Indiana

Years of operation More than 100 years

Size of property 40 ac

Geologic setting Lacustrine and fluvial sediments

Soil type and stratigraphy Clay interbedded with some fine silt and sand layers

Contaminants detected LNAPL VOCs, lead, PCBs, and PAHs

COC Lead and PCBs

Depth to groundwater Less than 1.5 m (5 ft) beneath the surface of the ground

Highest CRF GW ranking Benzene 19.4

Highest CRF SOIL ranking PCBs 2524

Geovulnerability ranking 71