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Ecological Risk Assessment

Frequently Asked Questions

Screening Level Ecological Risk Assessments

  1. Does a site visit need to be conducted for a screening level ecological risk assessment?
  2. What type of information should be presented in the environmental setting section of ecological risk assessments?
  3. What should be presented in the Site Conceptual Model (SCM)?
  4. When should the ecological risk assessor start the process of trying to establish whether or not endangered species may be present at a site?
  5. Does a wetland delineation need to be conducted as part of the ecological characterization of the site?
  6. Does a functional assessment of any identified wetlands need to be performed as part of the ecological characterization of the site?
  7. Can a Screening Ecological Risk Assessment be completed utilizing pre-remedial data?
  8. When discussing contaminants known or suspected to exist at a site, should the discussion be limited to available analytical data?
  9. Should the Screening-Level Ecological Risk Assessment be incorporated into the Remedial Investigation Report?
  10. During a SERA problem formulation, what type of fate and transport information should be considered and ultimately presented in the SERA report?
  11. Why should the fate and transport information be considered so early in the screening process?
  12. Must a fate and transport analysis be performed for each potential contaminant of concern?

1. Does a site visit need to be conducted for a screening level ecological risk assessment?

It is strongly recommended that a site visit be conducted during the problem formulation phase of the screening level assessment (Step 1) by the primary ecological risk assessor. The use of The Checklist for Ecological Assessment / Sampling (Appendix A of ERAGS Appendix B) or similar checklists (such as the RBP checklists) is strongly encouraged to ensure that adequate information is collected and reported to properly develop the problem formulation.

If the site visit and ecological characterization is not conducted by the primary ecological risk assessor, it is strongly recommended that the checklists be completed by appropriately trained personnel (i.e., biologists, ecologists, etc.) and be reviewed by the primary ecological risk assessor. This should be completed as early as possible in the risk assessment process to ensure the ecological characterization of the site has been properly completed and can be used during the subsequent problem formulation to accurately identify site conditions. While the completed checklists do not need to be included in the risk assessment report(s), care must be take to ensure that the checklists are properly completed (unbiased and accurately report site conditions).

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2. What type of information should be presented in the environmental setting section of ecological risk assessments?

The environmental setting sections of both Screening Level Ecological Risk Assessments (SLERA) and Baseline Ecological Risk Assessments (BERA) should focus on providing detailed habitat descriptions which include:

While not required, BTAG encourages the inclusion of photographs of habitats and key topographic features as part of the ecological risk assessment report.

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3. What should be presented in the Site Conceptual Model (SCM)?

The information that should be presented in the SCM is detailed in ERAGS. It is critical to note that the SCM must not be limited to an exposure pathway / fate-and-transport diagram. Detailed supporting discussion should be included in the risk assessment.

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4. When should the ecological risk assessor start the process of trying to establish whether or not endangered species may be present at a site?

Letters to the cognizant natural resource agencies requesting the identification of endangered and threatened species should be prepared and submitted at key phases of a remedial project. These include the initiation of the ecological risk assessment, during the work plan development phase, prior to the submission of the risk assessment reports (SLERA and BERA), and during the preparation of the proposed plan. The resultant responses from the natural resource agencies should be included as appendix to SERA and / or BERA. In the event that the potential occurrence of an endangered or threatened species has been identified, both the BTAG and the RPM should be notified immediately.

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5. Does a wetland delineation need to be conducted as part of the ecological characterization of the site?

No. However, if wetlands are suspected to be present onsite Section 404 of the Clean Water Act may be an ARAR and delineation of the wetland is likely to be necessary to properly complete a Feasibility Study and any subsequent Remedial Design and Remedial Action activities. A delineation should be performed at the RI/FS stage whenever the response action may adversely impact the wetlands.

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6. Does a functional assessment of any identified wetlands need to be performed as part of the ecological characterization of the site?

No, however a wetland functional assessment may be necessary prior to proposing and evaluating mitigation measures for wetlands impacts. The wetland functional assessment can provide important data to evaluate the potential ecological effects of a response action on potentially impacted wetlands. This data may be factored into the ecological risk assessment.

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7. Can a Screening Ecological Risk Assessment be completed utilizing pre-remedial data?

Yes. Depending on the available data set (quality, locations of sample stations, analytical parameters, etc.) it is recommended that the SERA be completed utilizing this data in order that the Baseline Ecological Risk Assessment Work Plan can be incorporated into the RI/FS Work Plan. At a minimum, the SERA must be completed as expeditiously as possible in order that the findings of the subsequent BERA, if required, can be incorporated into the RI Report.

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8. When discussing contaminants known or suspected to exist at a site, should the discussion be limited to available analytical data?

No, discussions of contaminants known or suspected to exist at a site should also include a description of the site history and the activities that are known or suspected to have occurred. This information is often useful in identifying contamination that may be attributable to the site or provide data key to assessing fate and transport mechanisms.

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9. Should the Screening-Level Ecological Risk Assessment be incorporated into the Remedial Investigation Report?

The SERA should be completed well in advance of the RI Report. The Baseline ERA should be incorporated into, or submitted concurrently with the RI Report. The results of the complete ERA process are necessary to ensure that the FS presents alternatives that are protective of the environment.

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10. During a SERA problem formulation, what type of fate and transport information should be considered and ultimately presented in the SERA report?

At a minimum, all contaminant migration pathways should be identified. Where the contaminants are physically located and where they are suspected or likely to be transported or move to should be evaluated. For the SERA the highest contaminant concentrations measured on site should be documented for each medium. Probable degradation mechanisms (eg., UV degradation) should be identified and discussed.

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11. Why should the fate and transport information be considered so early in the screening process?

While there are many uses of the fate and transport information throughout both the ERA and RI process, some of the primary reasons for the evaluation of this data at the screening level are to assess the effectiveness of the sampling locations utilized up to that point, to identify daughter or breakdown products that might not normally be considered, and to identify data gaps that need to be addressed to evaluate potential exposure pathways. It should be noted that fate and transport data should be considered even before the onset of the screening process during the work plan development phase.

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12. Must a fate and transport analysis be performed for each potential contaminant of concern?

No. For the SERA report, it may be appropriate to limit the information presented to the chemical family or class level (e.g., inorganics, volatile organics, etc.). Utilizing data available that characterizes historical disposal practices and waste sources, key site specific chemicals can and should also be discussed.

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