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ASTM PS104 1998 Edition, January 10, 1998
Complete Document
Superseded By: ASTM E2081
Standard Provisional Guide for Risk-Based Corrective Action
Additional Comments: W/D S/S BY ASTM E2081
Page Count:101
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1. Scope

1.1 This provisional guide covers risk-based corrective action (RBCA), that is a consistent decision-making process for the assessment and response to chemical releases, based on the protection of human health and the environment. Chemical release sites vary greatly in terms of complexity, physical and chemical characteristics, and in the risk that they may pose to human health and the environment. The RBCA process recognizes this diversity by using a tiered approach that integrates site assessment and response actions with human health and ecological risk assessment to determine the need for remedial action and to tailor corrective action activities to site-specific conditions and risks. The evaluations and methods used begin with simple analyses in Tier 1 and move to more complex evaluations in Tier 2 and Tier 3. The process of gathering and evaluating data is conducted in a scaled fashion. Consequently, only that data that are necessary for that tier's decision-making are collected at each tier.

1.2 This provisional guide describes an approach for risk-based corrective action. It is intended to help direct and streamline the corrective action process and to complement but not to supersede federal, state, and local regulations. It can be used where there may not be a regulatory framework for corrective action where the user wishes to conduct corrective action such as sites in voluntary cleanup programs or under Brownfields initiatives. In addition, it can also be used as an over-arching framework when several different agency programs affect the site. Furthermore, the user should be aware of the federal, state, and local corrective action programs that are applicable for the site and, regardless of the program, federal, state, and local agency approvals may be required to implement the processes outlined in this provisional guide. Finally, regardless of whether a corrective action is specifically governed by a regulatory program, the user should consult with the regulatory agency to identify the appropriate technical policy decisions prior to implementing the RBCA process.

1.3 There are numerous technical policy decisions that must be made to implement the RBCA process, including defining data quality objectives, determining target risk levels, and addressing resource protection. It is not the intent of this provisional guide to define appropriate technical policy decisions. The user must identify the appropriate technical policy decisions.

1.4 The general performance standard for this provisional guide requires that:

1.4.1 Technical policy decisions be identified prior to beginning the process,

1.4.2 Data collected during the site assessment, including historical data as well as new data collected during the site assessment, will be of sufficient quantity and quality to answer the questions posed at each tier of investigation which support the decisions made at the conclusion of each tier evaluation,

1.4.3 Actions taken during the risk-based decision process will be protective of human health and the environment,

1.4.4 Applicable federal, state, and local regulations will be followed (for example, waste management requirements, ground water designations, worker protection) and,

1.4.5 Remedial actions implemented will not result in higher risk levels than existed prior to taking actions.

1.5 ASTM standards are not federal or state regulations, they are consensus standards that can voluntarily be followed.

1.6 The RBCA process is not limited to a particular class of compounds. This provisional guide is intended to be a companion to Guide E 1739, and does not supersede that document for petroleum releases. If a release site contains a mixture of releases of petroleum and other chemicals, this provisional guide should be followed.

1.7 The United States Environmental Protection Agency (USEPA) has developed guidance for human health risk evaluation. Many of the components of this guidance have been integrated into the RBCA framework. The science of ecological risk assessment and the process by which the science is applied, are not as well-defined and agreed upon as human health risk assessment. Therefore, the information provided in this provisional guide for each tier evaluation for relevant ecological receptors and habitats is general; starting with simple screening methods for Tier 1 and increasing the complexity in subsequent tiers. The initial or qualitative ecological screening evaluation is an identification of relevant ecological receptors and habitats and a qualitative analysis of the actual or potential exposures of the relevant ecological receptors and habitats. If there are significant potential exposures then additional qualitative or quantitative analysis may be necessary based on site-specific conditions. The user should review USEPA, state and peer-reviewed publications, and peer-reviewed literature for more information (Appendix X5 provides additional information about the qualitative ecological screening evaluation and other general considerations).

1.8 The decision process described in this provisional guide integrates exposure and risk assessment practices with site assessment activities and remedial action selection to ensure that the chosen action is protective of human health and the environment. The following general sequence of events is prescribed in RBCA:

1.8.1 Define data requirements and develop data quality objectives and perform an initial site assessment and develop the first iteration of the site conceptual model,

1.8.2 Classify the site (see definition of site in 3.2.42) by the urgency of initial response (multiple sites at a single facility may have different classifications and require different response times and actions),

1.8.3 Implement an initial response action appropriate for the site based on the selected site classification,

1.8.4 Conduct a qualitative ecological screening evaluation to determine if relevant ecological receptors and habitats are present and if complete and potentially complete exposure pathways are present. If no relevant ecological receptors or habitats or complete and potentially complete exposure pathways exist, then no further action for relevant ecological receptors and habitats is warranted,

1.8.5 Compare concentrations of chemical(s) of concern at the site with human health Tier 1 Risk Based Screening Levels (RBSL), for complete and potentially complete exposure pathways, given in a look-up table determined to be applicable to the site and compare site conditions to Relevant Ecological Screening Criteria (RESC) determined to be applicable to the site,

1.8.6 If concentrations of chemical(s) of concern are below the RBSL for all complete and potentially complete exposure pathways, and comparison of site conditions to RESC indicate that there is no unacceptable risk to relevant ecological receptors and habitats from chemical(s) of concern, then no further action is warranted,

1.8.7 If concentrations of chemical(s) of concern are above the RBSL or comparison of site conditions to RESC indicate that there is an unacceptable risk to relevant ecological receptors and habitats from chemical(s) of concern, then one or more of the following actions is appropriate:

1.8.7.1 Further tier evaluation;

1.8.7.2 Implementation of interim remedial action;

1.8.7.3 Apply RBSL as remedial action target levels,

1.8.8 Define Tier 2 data requirements, data quality objectives, and collect additional site-specific information and up-date the site conceptual model, as necessary, if further tier evaluation is warranted,

1.8.9 Develop Site-Specific Target Levels (SSTL) and point(s) of compliance for complete and potentially complete exposure pathways or Site-Specific Ecological Criteria (SSEC), where appropriate (Tier 2 evaluation),

1.8.10 Compare the concentrations of chemical(s) of concern at the site with the Tier 2 evaluation SSTL at the determined point(s) of compliance or source area(s) and compare site conditions to SSEC,

1.8.11 If concentrations of chemical(s) of concern are below the SSTL for all complete and potentially complete exposure pathways and comparison of site conditions to SSEC indicate that there is no unacceptable risk to relevant ecological receptors and habitats from chemical(s) of concern then no further action is warranted,

1.8.12 If concentrations of chemical(s) of concern are above the SSTL or comparison of site conditions to SSEC indicate that there is an unacceptable risk to relevant ecological receptors and habitats from chemical(s) of concern, then one or more of the following actions is appropriate:

1.8.12.1 Further tier evaluation;

1.8.12.2 Implementation of interim remedial action, to change the site classification and facilitate reassessment of the tier evaluation;

1.8.12.3 Apply SSTL as remedial action target levels, or identify appropriate remedial action for relevant ecological receptors and habitats,

1.8.13 Define Tier 3 data requirements, data quality objectives and collect additional site-specific information and update the site conceptual model, as necessary, if further tier evaluation is warranted,

1.8.14 Develop SSTL and point(s) of compliance or SSEC, where appropriate (Tier 3 evaluation),

1.8.15 Compare the concentrations of chemical(s) of concern at the site with the Tier 3 evaluation SSTL at the determined point(s) of compliance or source areas and compare site conditions to SSEC,

1.8.16 If concentrations of chemical(s) of concern are below the SSTL for all complete and potentially complete exposure pathways and comparison of site conditions to SSEC indicate that there is no unacceptable risk to relevant ecological receptors and habitats from chemical(s) of concern then no further action is warranted,

1.8.17 If concentrations of chemical(s) of concern are above the SSTL or comparison of site conditions to SSEC indicate that there is an unacceptable risk to relevant ecological receptors and habitats from chemical(s) of concern then one of the following actions is appropriate:

1.8.17.1 Implementation of interim remedial action to change the site classification and facilitate reassessment of the tier evaluation;

1.8.17.2 Apply SSTL as remedial action target levels or identify appropriate remedial action for relevant ecological receptors and habitats,

1.8.18 Develop and implement a remedial action plan to achieve the SSTL, as applicable,

1.8.19 Identify appropriate remedial action for relevant ecological receptors and habitats, based on the SSEC, as appropriate,

1.8.20 Develop a monitoring plan including the remedial action completion criteria to validate the assumptions used for the tier evaluation and to demonstrate effectiveness of the remedial action, as applicable.

1.9 This provisional guide is organized as follows: Section 2 lists referenced documents, Section 3 defines terminology, Section 4 describes the significance and use of this provisional guide, Section 5 is a summary of the tiered approach, and Section 6 presents the RBCA procedures in a step-by-step process. Appendix X1 provides guidance on developing technical policy decisions and building a RBCA program, Appendix X2 provides examples of chemical properties and effects data that may be useful for a RBCA evaluation, Appendix X3 provides an example Tier 1 Look-Up Table, Appendix X4 describes the use of predictive modeling, Appendix X5 describes an example process of a qualitative ecological screening evaluation, Appendix X6 provides guidance on institutional controls, and Appendix X7 includes illustrative examples of the application of the RBCA framework. The appendixes are provided for additional information and are not included as mandatory sections of this provisional guide.

1.10 Where the values are stated in English units, they are to be regarded as the standard. The SI units given in parentheses are for information only.

1.11 Provisional standards require only subcommittee consensus and are published for a limited time of two years. The provisional process was used because potential user's have an immediate need for a risk-based framework for chemical releases.

1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.