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Soil Screening Guidance for Radionuclides

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The U.S. Environmental Protection Agency (EPA) has developed this Soil Screening Guidance for Radionuclides as a tool for screening at radioactively contaminated National Priorities List (NPL) sites. This guidance presents a framework for developing soil screening levels (SSLs) for radionuclides, focusing primarily on a simple methodology for developing site-specific screening levels, but also including generic soil screening levels and detailed models for more complete site conditions. The guidance can serve as a tool to expedite the evaluation of radioactively contaminated soils at sites addressed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund. The guidance is intended to be used to screen out areas of sites, exposure pathways, or radionuclides of concern from further consideration, assuming certain conditions are present, or to determine that further study is warranted at a site. Its use may significantly reduce the time it takes to complete soil investigations and cleanup actions at some sites, as well as improve the consistency of these actions across the nation. The guidance was written to enhance the efficiency of remedial investigation/feasibility study (RI/FS) work at NPL sites but may be utilized at corrective action sites or voluntary cleanup sites where site conditions are similar.

The Soil Screening Guidance presents three recommended methods for developing risk-based, soil screening levels, but emphasizes a simple, site-specific approach. The formulae and exposure assumptions used to develop the screening levels are based on "Risk Assessment Guidance for Superfund" and have been widely accepted in the Superfund program for a number of years. These levels are then compared to on-site soil radionuclide levels. Generally, areas of a site which fall below the screening levels may be eliminated from further assessment. Areas above the screening levels generally warrant further evaluation of the potential risks that may be posed by radionuclides to determine the need for response action. The guidance is recommended for use as a screening tool where assumptions made developing the tool (e.g., residential land use, no ecological concerns) are consistent with conditions found to determine if further study of specific portions of a site is warranted. The levels should not be interpreted to represent cleanup standards for a site.

The Soil Screening Guidance for Radionuclides is presented as Portable Document Format (PDF) files in three documents: (1) a transmittal memo (PDF 184K, 3 Pages) entitled "Distribution of OSWER Soil Screening Guidance for Radionuclides: User's Guide and Technical Background Document Final Guidance"November 21, 2000; (2) a User's Guide,which provides details for implementing a simple methodology for calculating site-specific SSLs; and (3) a Technical Background Document, which presents generic SSLs and the technical foundation for the methodology for establishing SSLs. In addition, an electronic version of the risk assessment and groundwater leaching equations in the Soil Screening Guidance for Radionuclides is available for calculating site-specific SSLs and Preliminary Remediation Goals (PRGs) that account for radioactive decay and ingrowth.

The Soil Screening for Radionuclides guidance documents are similar to guidance documents issued by EPA entitled "Soil Screening Guidance: User's Guide" (OSWER No. 9355.4-23, April 1996) and "Soil Screening Guidance: Technical Background Document" (OSWER No. 9355.4-17A, May 1996). These 1996 guidance documents contain information regarding soil screening of chemical (non-radiological) contaminants found at Superfund sites across the nation. The 2000 Soil Screening for Radionuclides guidance documents are intended to be consistent with the 1996 chemical Soil Screening guidance documents except where it was necessary to be different based on a technical difference posed by radionuclides. Also available from the chemical Soil Screening Guidance effort is a (1) Quick Reference Fact Sheet, which provides an overview of the development and use of soil screening levels; and (2) an electronic version of the risk assessment and groundwater leaching equations in the chemical Soil Screening Guidance for calculating site-specific SSLs and Preliminary Remediation Goals (PRGs) for chemicals, including the systemic toxicity of Uranium.

The Soil Screening Guidance for Radionuclides is not a rule, does not have the force of a regulation, nor should it be interpreted to represent cleanup standards for a site. Use of the guidance is not legally binding either on EPA staff or on other parties; rather it is intended to be a tool available for use under appropriate site-specific conditions. NPL sites do not all meet the conditions necessary for its use; consequently, EPA does not expect this tool to be useful at all NPL sites. EPA staff applying the guidance have discretion to follow it or diverge from it as site-specific conditions may warrant, and each site-specific action will be explained on its own record. Concentrations in soil above these screening levels do NOT automatically designate a site as dirty, nor trigger a response action. SSLs do not supersede existing federal or state ARARs that may affect selection of cleanup levels for soils.

"Soil Screening Guidance for Radionuclides: User's Guide" October 2000. OSWER Directive 9355.4-16A, NTIS Order Number (PB2000 963307)

The Soil Screening Guidance for Radionuclides is a tool developed by EPA to help standardize and accelerate the evaluation and cleanup of radioactively contaminated soils at sites on the National Priorities List (NPL) where future residential land use is anticipated. The User's Guide provides a simple step-by-step methodology for environmental science/engineering professionals to calculate risk-based, site-specific soil screening levels (SSLs) for radionuclides in soil that may be used to identify areas needing further investigation at NPL sites.

Entire Document (88 pp, 1.6M)

By Chapters
Soil Screening Guidance for Radionuclides: User's Guide (7 pp, 93K)
Part 1 - Introduction (7 pp, 217K)
Part 2 - Soil Screening Process (30 pp, 239K)
Reference (4 pp, 18K)
Attachment A (18 pp, 94K)
Attachment B (5 pp, 15K)
Attachment C (9 pp, 25K)
Attachment D (8 pp, 28K)

"Soil Screening Guidance for Radionuclides: Technical Background Document" October 2000.OSWER Directive 9355.4-16, NTIS Order Number (PB2000 96330)

This document provides the technical background for the development of methodologies described in the "Soil Screening Guidance for Radionuclides: User's Guide", along with additional information useful for soil screening of radioactively contaminated sites. Together, these documents define the framework and methodology to develop soil screening levels (SSLs) for radionuclides.

Entire Document (152 pp, 2M)

By Chapters
Soil Guidance for Radionuclides: Technical Background Document (11 pp, 68K)
Part 1 - Introduction (7 pp, 63K)
Part 2 - Development of Pathway-Specific/Soil Screening Levels (33 pp, 135K)
Part 3 - Unsaturated Zone Models for Radionuclide Fate and Transport (25 pp, 383K). For further information, see the technical report supporting Part 3.
Part 4 - Measuring Radionuclide Concentrations in Soil (48 pp, 184K)
Part 5 - Radionuclide-Specific Parameters (6 pp, 24K)
Part 6 - References (7 pp, 29K)
Appendix A (12 pp, 53K)
Appendix B (3 pp, 13K)

 

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