Environmental Analysis Tools - Environmental Impact Analysis: Process and Methods - page 271

The combination of assessment and measurement endpoints serve multiple
purposes:
r The measurement endpoints are the primary input to the design
of any ecological data collection effort. Any data collected should
be directed at quantifying or otherwise evaluating the status of the
measurement endpoint at the site; otherwise the use of the data is
uncertain at best and frequently useless.
r The status of the endpoint at the site indicates to what degree the
contamination has caused an ecological risk.
r The endpoints are a mechanism to evaluate the success of the
cleanup following remediation.
r The endpoints focus the scope of the risk assessment making it
limited and manageable.
An example of endpoints and associated attributes for a typical hazardous
waste site with multiple ecological receptors is illustrated in Table 7.1.
7.2.4 ScreeningLevelAssessment
The objective of screening is to determine, based on limited data and infor-
mation, whether there is definitely a risk; definitely not a risk; or the risk
to ecological receptors is unknown (Figure 7.1). Similar to the screening
of alternatives in an environmental impact analysis (see Section 4.5.3), the
screening-level assessment identifies the concerns (as indicated by ecological
endpoints) that should be the focus of additional investigation and consid-
eration in remediation and other decisions. There are two topics covered by
the screening-level assessment: the potential exposure of ecological recep-
tors (included as endpoints) and degree of contamination.
The assessment of potential presence and exposure of receptors is the simpler
of the two types of screening. It can frequently be accomplished as part of the
ecological site description (see Section 7.2.3) by an experienced ecologist. Based
on a simple site reconnaissance, the ecologist can generally determine from the
habitat present, which species and communities would be expected on the site,
and which potentially contaminated environmental media they may contact to
produce exposure. If the site is a fully developed and largely paved oil refinery,
the ecological resources would be extremely limited and there would be few, if
any, appropriate assessment endpoints. In such a case, the ecological risk assess-
ment might be limited to effects from off-site migration. At the other extreme, if
the contamination has reached or has the potential to reach an area comprised
of a complex native vegetative cover encompassing both a standing and flow-
ing water habitat, the need for a detailed ecological risk assessment cannot be
ruled out based on the potential presence of receptors and their exposure. A
common mistake made by nonecologists in screening for receptors is to pre-
maturely conclude that there are no sensitive resources actually present, so a