Environmental Engineering Reference
In-Depth Information
perspective by actually cleaning up sites of environmental contamination. Therefore, to
evaluate whether certain geologic units are vulnerable to contamination, a comparison
between specific sites located in low geologic vulnerability areas to sites located in high
geologic vulnerability areas must be conducted. If valid, the geologic vulnerability map-
ping should confirm that the sites situated above high vulnerability locations pose greater
risk of exposure than sites located above low vulnerability locations.
For this analysis, a site of low vulnerability located in a geological environment pre-
dominantly composed of clay sediments (Site 1) is compared to a high vulnerability site
located in a geological environment predominantly composed of sand (Site 2). Both sites
are located in the Rouge River watershed and are separated by only 11 km (7 mi). However,
Site 1 (1) is significantly larger than Site 2 (approximately twice the size), (2) has a much
longer heavy industrial operational history (operated approximately 40 years longer), and
(3) has significantly more contamination and types of contaminants (nearly 10 times the
mass and three times as many contaminants) released into the environment.
Without considering the geology of each site, it would be logical to assume the environ-
mental risks were higher at Site 1, and the associated clean up costs would be higher and
reflect its contamination history. We now determine if the vulnerability map predicts these
outcomes.
6.5.1 Site 1: Low Vulnerability Site
Site 1 is a former heavy manufacturing facility located on approximately 16 ac of land
that operated for approximately 70 years. A Phase I environmental site assessment was
required by the lending institution and conducted due to a real estate transaction involv-
ing the property. This initial assessment identified six recognized environmental condi-
tions (RECs).
During the next investigational period (Phase II), several subsurface investigations
were conducted at the facility and four main sources of contaminant release were identi-
fied that required remediation. These sources are shown as areas of impact on Figure 6.4
and include (1) surface spills, (2) an aboveground storage tank, and (3) spills and leaks of
hazardous liquids located in waste storage areas. Other sources or releases were identi-
fied during the course of evaluating the site but were not severe enough to warrant fur-
ther action.
The six RECs identified during the Phase I investigation included
•
Former chemical storage areas
. Evidence of surface staining indicating some spillage
of liquids was observed on bare ground near the two former storage areas. No
staining was observed near the current storage area.
•
Current storage area
. The current storage area was located inside the main manu-
facturing building (northern building). The concrete flooring was heavily cracked,
providing a potential pathway for spills and leaks to contaminate the ground
beneath the building.
•
A former above-ground storage tank that stored gasoline
. A limited amount of surface
staining was observed at the general locations of the tank.
•
Surface soil staining and stressed vegetation
. These conditions were observed near a
backdoor of the facility and close to an inside location where maintenance activi-
ties were conducted and dense nonaqueous phase liquid (DNAPL) solvents were
used.
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