Environmental Engineering Reference
In-Depth Information
4.2.3 Phase II Investigation
When a Phase I ESA has been completed and there are one or more RECs identified, a
Phase II investigation will likely be required to confirm the existence of the REC(s). The
scope of Phase II investigations vary widely and largely depend on the RECs identified in
the Phase I ESA. Under normal circumstances, a Phase II investigation will involve the col-
lection and analysis of samples collected from the area identified as a REC in the Phase I
ESA. These samples are collected and analyzed to evaluate the specific contaminants pres-
ent, and if they exceed federal- or state-mandated concentrations for protection of human
health and the environment.
An example of the sampling procedure is shown in Figure 4.5a. This map shows an
industrial site where a Phase I ESA was conducted; the 25 RECs and 5 environmental con-
cerns discovered are represented by circles enclosing the letters A through DD. Figure 4.5b
shows the location of soil borings drilled during the Phase II investigation at the same site
used to evaluate each of the RECs and environmental concerns. A comparison of the two
figures indicates the soil borings were drilled in close proximity to each of the RECs and
environmental concerns. Figure 4.5b also identified areas where chemicals were stored
or used; this information assisted with the selection of analytical testing parameters and
associated field sampling procedures.
Further examination of Figure 4.5a and b reveals soil borings drilled in areas not associ-
ated with any REC. These borings were drilled primarily along the western and eastern
boundaries and in isolated areas in the central portion of the site for three reasons:
1. To evaluate background conditions in areas not believed to be impacted. This
assessment is routine because heavy metals naturally occur in the environ-
ment, and are likely to be present at large properties where there are numerous
RECs.
2. To evaluate contamination migration potential onto the site from an off-site source.
The results can determine if an off-site source has impacted the property.
3. To more fully characterize the site geology and hydrogeology, since these site attri-
butes can, and typically do change over short distances. Accurately characterizing
the geology and hydrogeology of any site is the key to evaluating the nature and
extent of contamination.
Phase II investigations are designed to use the scientific data gathered from each step to
evaluate the need for, or to plot the direction of the subsequent step(s). The USEPA has
published guidance for conducting investigations under the CERCLA (1988) and under
the Resource Conservation and Recovery Act (RCRA) 1986. In addition, many States have
published guidelines for conducting investigations; e.g., New Jersey (2005), Ohio (1995,
2006), and California Environmental Protection Agency (1995).
The investigative process follows three steps consisting of find, define, and refine. Each
step in the sequence is described in greater detail as follows (Rogers et al. 2009):
•
Find
: This type of investigation has the dual purpose of finding and identifying
specific contaminants and is accomplished by collecting and analyzing biased or
“worst-case” samples. Examples of “worst-case” samples are those: nearest the
source of the release, directly beneath an outfall, appearing the most heavily-
stained, exhibiting the strongest odor, or those registering the highest readings on
field-screening equipment.
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