USEPA Environmental Response Team (Cont.)

This document describes, with examples, eight steps for doing an ecological risk

assessment. Steps 1 and 2 of the EPA guidance are designed to allow risk

assessors and risk managers to quickly determine whether a site poses a risk to the

environment.

Step 1 - Screening-level problem formulation and ecological effects evaluation

In the problem formulation component of Step 1, all parties involved in the

risk assessment, including site managers, risk assessors, the Biological Technical

Assistance Group (BTAG), the Potentially Responsible Party (PRP), and

stakeholders, work together to define the goals of the assessment and to propose a

scope for remedial action. This problem formulation step is critical to focus the

scope of work for the risk assessment. Step 1 also includes a toxicity evaluation to

determine what specific component of the ecosystem could be adversely affected

by contaminants from the site (ecological effects evaluation).

Step 2 - Screening-level estimate and risk calculation

The goal of this step is to decide whether a significant ecological risk has been

identified, based on screening assessment results, or if a more detailed risk

assessment should be conducted. At the end of Step 2 is a scientific/management

decision point (SMDP). SMDPs occur at defined points in the assessment process.

The purpose of SMDPs is to guide work, discuss the uncertainty of risk

assessment, and to keep lines of communication open between parties working on

the assessment. In this way, SMDPs ensure that time and money are not wasted

due to flawed decisions, miscommunication, or misunderstandings while

conducting the risk assessment.

Step 3 - Baseline risk assessment and problem formulation

If the results of the screening-level assessment from Steps 1 and 2 prove

insufficient to rule out risk to the environment or if they indicate that some

significant risk is present, then the assessment proceeds to Step 3. This step uses

the screening assessment results in conjunction with more site-specific

information to refine the problem formulation and expand on ecological issues of

concern. Specifically, assessment endpoints, exposure pathways, and risk

questions are developed. Step 3 also involves the development of a site conceptual

model, which integrates the above three components. The purpose of the SMDP at

the end of Step 3 is to determine if this conceptual model is acceptable.

Step 4 - Study design and data quality objective process

Step 4 uses the conceptual model developed in Step 3 to define measurement

endpoints, data quality objectives (DQOs), and the study design. These

components are directly integrated into the products of Step 4, an ecological risk

assessment work plan (WP) and a sampling and analysis plan (SAP). The WP and

SAP are critical to be able to gather enough information for the risk assessor to

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Appendix A Summary of Federal, State, and Regional Guidance