Chuck Nace United States Environmental Protection Agency Region 2

Transcription

1 (asbestos) (decision) (tree) Chuck Nace United States Environmental Protection Agency Region 2 USEPA Regional Risk Assessors Conference San Francisco, CA 05/01/06 05/04/06

2 TRW Asbestos Committee Subcommittee of the Technical Review Workgroup convened in April 2005, although core group working on asbestos issues since 2003 ~26 participants from regions (1, 2, 4, 5, 6, 8, 9, and 10), OSWER, OSRTI, ORD, ERT, OPPT, OAQPS, OEM, NEIC, and ATSDR Charge to develop new guidance concerning site assessment and cleanup at hazardous waste sites contaminated by asbestos; and provide site consultation in support of regional requests Bi-weekly conference calls and semi-annual workshops

3 Issues OSWER Directive indicated 1% definition of asbestos should not be used and that a risk-based, site-specific action level should be used when evaluating the need for removal or remedial actions. Soil concentrations/dust concentrations not adequate measure of what is inhaled Methods for extrapolating from soil/dust are not available Best measure for asbestos exposure is an air concentration

4 Key Components of Decision Tree To present a framework for investigating and evaluating the potential for asbestos contamination at removal and remedial sites. 16 step process Addresses outdoor and indoor exposures Incorporates the latest analytical methodologies Provides details on several different risk assessment models to allow bounding-estimate of risk

5 Outline Introduction Background Mineralogy Fiber definition Sampling methodology Analytical methodology Toxicity assessment Framework Decision tree Types of remedial activities Limitations Appendix A OSWER Directive Appendix B Asbestos fact sheet Appendix C SOP for Activity-based sampling Appendix D Analytical methodology Appendix E Risk Assessment Models Appendix F Libby, MT and Sister-sites Appendix G SOP for Glove box Appendix H Derivation of surface criteria

6 Purpose Asbestos Decision Tree 03/15/06 Draft DRAFT DRAFT Do not Cite or Quote Step 1 Does the site meet one or more of the following criteria: (a) contain asbestos-containing material, or (b) is asbestos expected due to past practices or from naturally-occurring sources, or (c) has asbestos been detected in site-related media. Site Step 2 Is there a threat of release? Characterization Outdoor (may proceed directly to Step 7 or 10 see text) Step 3 Are human pathways present and complete current or future? Step 4 Perform typical site evaluation to confirm presence or absence of asbestos Indoor (may proceed directly to Step 14 or 16 see text) Qualitative Screening Step 5 Evaluate potential for fibers to be released from the soil Step 6 Do results indicate release of fibers or that fiber concentration is greater than background? DRAFT Step 11 Conduct microvacuum sampling Step 12 Do results indicate release of fibers above criterion (200 s/cm 2 ) or greater than background? Quantitative Evaluation Step 7 Remediate or implement institutional controls OR Proceed to site-specific activity-based sampling Step 8 Conduct site-specific activity-based sampling Step 13 Do results indicate release of fibers above criterion (>100,000 s/cm 2 )? Step 14 Conduct activity-based indoor air sampling Remediate OR Proceed to indoor air sampling DRAFT Step 9 Do results indicate air concentrations that exceed risk-based values or show that air concentrations are greater than background? Remedial Decision Step 10 Remediate or implement institutional controls DRAFT Step 15 Do results indicate air concentrations that exceed risk-based values or show that air concentrations are greater than background? Step 16 Remediate or implement institutional controls

7 Site Characterization

8 Purpose Asbestos Decision Tree Draft Do not Cite or Quote Site Characterization Step 1 Does the site meet one or more of the following criteria: (a) contain asbestos-containing material, or (b) is asbestos expected due to past practices or from naturally-occurring sources, or (c) has asbestos been detected in site-related media. Step 2 Is there a threat of release? Step 3 Are human pathways present and complete current or future? Step 4 Perform typical site evaluation to confirm presence or absence of asbestos

9 Outdoor Screening/ Evaluation/Decision

10 Purpose Asbestos Decision Tree Draft Do not Cite or Quote Qualitative Screening Quantitative Evaluation Remedial Decision Outdoor (may proceed directly to Step 7 or 10 see text) Step 5 Evaluate potential for fibers to be released from the soil Step 6 Do results indicate release of fibers or that fiber concentration is greater than background? Step 7 Remediate or implement institutional controls OR Proceed to site-specific activity-based sampling Step 8 Conduct site-specific activity-based sampling Step 9 Do results indicate air concentrations that exceed risk-based values or show that air concentrations are greater than background? Step 10 Remediate or implement institutional controls

11 Outdoor Generic Activity-Based Sampling Uses an activity that provides a high-end soil disturbance Currently recommend a raking scenario Rake for specified time over a template area Collect personal air samples and perimeter air samples Provides a measure of fiber release from soil

12 Outdoor Glove Box Collect soil samples from site, typically using a grid Samples are disturbed within the glove box Air samples are collected Provides a measure of fiber release from soil Presence/absence Semi-quantitative More research needed for quantitative comparison

13 Outdoor Site-Specific Activity-Based Sampling Develop site-specific ABS that represents activities of interest Such as mowing lawns, playing sports, hiking, biking, pushing stroller Collect personal air samples and perimeter air samples Provides measure of fiber release for specific activities Resource intensive

14 Outdoor Hikers Adult canister Child canister

15 Outdoor ATV Riding in Full Protection

16 Indoor Screening/ Evaluation/Decision

17 Purpose Asbestos Decision Tree Draft Do not Cite or Quote Qualitative Screening Indoor (may proceed directly to Step 14 or 16 see text) Step 11 Conduct microvacuum sampling Step 12 Do results indicate release of fibers above criterion (200 s/cm 2 ) or greater than background? Quantitative Evaluation Step 13 Do results indicate release of fibers above criterion (>100,000 s/cm 2 )? Step 14 Conduct activity-based indoor air sampling Remediate OR Proceed to Indoor air sampling Step 15 Do results indicate air concentrations that exceed risk-based values or show that air concentrations are greater than background? Remedial Decision Step 16 Remediate or implement institutional controls

18 Indoor Microvacuum ASTM 5755 method Low-suction vacuum Captures dust and fibers on filter cassette Preserves dust matrix Provides a qualitative measure of fibers in settled dust

19 Indoor Indoor Air Sampling Activity-based sampling, if possible, if not, then surrogate using fans/leaf blower recommended Collect air samples Provides quantitative estimate of fibers in air

20 Developing Risk-based Criteria Screening values, risk estimates, and preliminary remediation goals use the toxicity value recommended in IRIS and methodology from RAGS only available for inhalation Other models available that assign different toxicity values for asbestos types (chrysotile vs. amphibole) and fiber sizes also only for inhalation Recommended to use to provide bounding estimates, especially when chrysotile is not the primary form of asbestos Appendix D provides information on the other models and their use

21 Background & Z-test Framework stresses the need to establish background concentrations for asbestos by conducting the same sampling in a reference or background location Allows statistical comparison of site data with background data using a Z-test Analysis can be used in conjunction with risk estimates to determine the appropriate remedial decision

22 Next steps National Association of Remedial Project Managers (NARPM) presentation Date: June or 19-23, 2006 Location: New Orleans, LA Two-hour session titled: Advances in Asbestos Investigations and Evaluations Sampling, Analysis, and Policy Implications Finalize document within TRW Asbestos Committee Intra-agency review on regional and programmatic level Some level of peer review Eventually released as a document

23 Contact Technical Review Workgroup Asbestos Committee Tri-chairs Aubrey Miller R8 Arnold Den R9 Mark Maddaloni R2 Hotline number: