Environmental Analysis Tools - Environmental Impact Analysis: Process and Methods - page 277

r Concentrations of all metals in on-site surface waters create syner-
gism resulting in impaired growth and survival of aquatic organisms.
Comparable to technical scoping in environmental impact analysis (see
Section 4.3.2), it is critical that the design of the BERA investigation receives
full key stakeholder buy-in before the studies are initiated. In the case of
ecological risk assessment, it is even more important because the “key stake-
holders” are the scientists representing the regulatory agencies that make
the final decision on risk and site remediation. If sample collection methods,
analytical procedures, quality assurance procedures, or concentration detec-
tion limits don't meet the expectations of the regulatory agency scientists,
the entire risk assessment will be called into question, and the investigations
may need to be repeated incurring significant costs and delays.
Conducting the detailed investigations can be the most revealing and
rewarding phase of the ecological risk assessment to the ecologists and
other scientists working on the site characterization. These studies repre-
sent real science and frequently employ state-of-the-art methods. As pointed
out above, each investigation must address a specific question and relate to
a measurement endpoint. Examples of detailed investigations conducted to
support ecological risk assessments at aquatic sites are presented in Table 7.3.
Comparable studies are frequently conducted at sites with risk to terrestrial
receptors with the focus on soils and plants as the contaminated media and
exposure pathways of concern.
Depending on the degree of contamination, extent of risk, level of uncer-
tainty, and potential remediation costs, very sophisticated, long-term and
expensive investigations are sometimes conducted to identify the need/
extent for remediation. The investigation can involve testing to track expo-
sure pathways and identifying remediation approaches to disrupt the expo-
sure pathways rather than risk large-scale media cleanup. Also if the studies
typically conducted as part of a BERA (Table 7.3) indicate risk to individuals,
but the assessment endpoints are at a higher level of biological organiza-
tion (e.g. populations), ecological modeling may be necessary (Pastorok et al.
2002). The modeling can be conducted on the population, ecosystem, or land-
scape scales to determine if the loss of some percentage of the individuals
would be translated to a broader-scale risk.
7.2.6 ExposureCharacterization
There are two integrated components of exposure: 1) if and how a contact is
made between a contaminant (or other stressor for a nonhazardous waste risk
assessment); and 2) the contaminant concentration (or level of stress) at the
point of exposure. Thus the objective of the exposure characterization is to
determine or estimate both of these factors for each ecological receptor repre-
senting a target in an ecological endpoint. The evaluation of contact is the first
of these two components to be conducted and characterization of contact is