Case Studies: Successful and Unsuccessful Redevelopment of Contaminated Sites - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 489

• Case Studies 1 (Michigan), 3 (Indiana), and 6 (New Jersey) were all foundries. All
are located in areas with vulnerable geology, but only the site that used significant
amounts of DNAPL VOCs (Michigan) experienced a synergistic effect between
vulnerable geology and a chemical with a high contaminant risk factor. It is rea-
sonable to conclude that the high contaminant risk factor for groundwater of
DNAPL VOCs contributed to the synergistic effect.
• Case Studies 2 (Illinois) and 5 (California) are located in areas of different geo-
logical vulnerability, but both had chromium VI as the contaminant of concern.
The masses of chromium VI released were nearly the same and occurred over a
similar span of time (less than 40 years). The Illinois site is located in a much less
geologically vulnerable area (rating of 13) compared to the California site (rating
of 63). The synergistic effect occurred because the California site was located in a
vulnerable geological environment.
• Case Study 4 (Wisconsin) provides an example of how anthropogenic influence
represented by the presence of storm sewers and building foundations greatly
influences groundwater and contaminant migration.
• Case studies 1, 2, 4, 5, and 6 demonstrate the value provided by structure demoli-
tion. This measure enables unobstructed access to the subsurface and assists with
site investigation and remediation.
• Damaged sites can be effectively redeveloped into different land uses (Case stud-
ies 4 and 6).
• Case studies 1, 2, 3, 4, and 6 highlighted low areas being the sources of contamina-
tion, that is, sumps, pits, trenches, floor drains, and tanks. Outdoor storage areas
are also identified as contaminant sources. Identification of these sources provides
a basis for instituting pollution prevention initiatives, especially at those locations
where a synergistic effect may occur.
• Remediation of soil at each of the case studies relied on soil excavation as part of
the remedial process. Other remedial efforts included a variety of technologies,
and in most cases a combination of options was required to successfully achieve
remedial goals.
• The presence of synergistic effects is a key determinant of cost. In the six cases pre-
sented, the costs of investigation ranged from $400,000 to more than $25 million.
The case studies costing the most (Michigan and California) are located where
synergistic effects were present, and those costing the least (Indiana and Illinois)
were located where a synergistic effect was not present.
The cases in Michigan and California (Case Study 1 and 5) were unsuccessful because the
synergistic effects at these sites: (a) were extensive and created investigative and reme-
dial work that exhausted available financial resources, (b) will require decades to be fully
remediated, and (c) required time-consuming involvement from several different public
and private entities. By contrast, the case studies in Illinois, Indiana, Wisconsin, and New
Jersey (Case Study 2, 3, 4, and 6) were successful mainly because the full synergistic effect
was not realized, and this kept the investigation, remediation, and subsequent redevelop-
ment of these sites more manageable.
We now use the outcomes from these studies, and from the thousands not described
here, to investigate ways to attain sustainable development within urban watersheds.