| (10) make a recommendation for managing ecological risk at the affected property based on the final ecological PCLs, unless proceeding under Tier 3 (may be included as part of the affected property assessment report, self-implementation notice, or the response action plan). (d) Tier 3: site-specific ecological risk assessment. When any of the Tier 2 PCLs, as described in subsection (c) of this section, are considered by the person to be inappropriate or not reflective of existing conditions at the affected property, or when otherwise elected, the person may conduct a site-specific ecological risk assessment. If the person elects to begin the ecological evaluation of the affected property by proceeding directly to a site-specific ecological risk assessment, applicable components of a Tier 2 screening-level ecological risk assessment shall be incorporated, including subsections (c)(2) - (4), (8), and (10) of this section and other requirements of subsection (c) of this section as determined appropriate by the executive director. The purpose of the optional site-specific ecological risk assessment shall be to incorporate additional information obtained through the performance of site-specific studies designed to provide a more empirical evaluation of ecological risk at the affected property. The result of the site-specific ecological risk assessment will be the development of site-specific Tier 3 PCLs, a determination that there is no ecological risk, or a conclusion that ecological risk is not apparent based on site-specific information. Site-specific studies which may be conducted include but are not limited to: (1) development of site-specific bioaccumulation factors through the collection and analysis of tissue samples from appropriate ecological receptors. (2) performance of toxicological testing of the impacted media via exposure to an appropriate test species. (3) comparison of site data (e.g., macroinvertebrate diversity surveys) to like data from a reference area. (4) other studies designed to obtain a preponderance or "weight-of-evidence" to draw conclusions about ecological risk. (e) Cross-media transfers of COCs. In situations where cross-media transfer of a COC from a source medium to a POE within an exposure medium must occur for the receptor to be exposed, then the person shall use the cross-media natural attenuation factor equations as shown in the figure in §350.75(b)(1) of this title (relating to Tiered Human Health Protective Concentration Level Evaluation) to calculate the PCL. In lieu of using the human health RBEL referenced in the figures, the person shall use the ecological PCL established under subsections (c) or (d) of this section. (f) Ecological risk management options. After the ecological risk has been quantified and PCLs have been established as specified in subsections (c) or (d) of this section and it has been determined that the ecological PCL is the critical PCL, or is the only PCL, the person may either: (1) take action to remove and/or decontaminate the impacted media and COCs as described in §350.32 of this title (relating to Remedy Standard A); or (2) remove, decontaminate, and/or control the impacted media and COCs or, when after consultation with the Natural Resource Trustees, it is determined appropriate by the executive director, conduct an ecological services analysis in accordance with §350.33 of this title (relating to Remedy Standard B). The ecological services analysis considers the ecological risks and benefits of the potential response actions available under Remedy Standard B at the affected property and, as appropriate, factors in compensatory ecological restoration in lieu of or in addition to remediation as a means of managing residual ecological risk. |
| Source Note: The provisions of this §350.77 adopted to be effective September 23, 1999, 24 TexReg 7436; amended to be effective March 19, 2007, 32 TexReg 1526; amended to be effective March 19, 2009, 34 TexReg 1866 |
