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Remedial Action Guideline Revisions

Remedial Action Guideline Revisions. David Wright, Director Division of Remediation, BRWM. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION Protecting Maine’s Air, Land and Water. Presentation Outline. Setting Clean-up Goals at Hazardous Substance Sites. Remember ….

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Remedial Action Guideline Revisions

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  1. Remedial Action Guideline Revisions David Wright, Director Division of Remediation, BRWM MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION Protecting Maine’s Air, Land and Water

  2. Presentation Outline

  3. Setting Clean-up Goals atHazardous Substance Sites

  4. Remember … RAGs are guidelines, notrules, & not “standards”

  5. RAGs use a “Risk Based” Approach

  6. RAGs use a “Risk Based” Approach • RME: Reasonable Maximum Exposure - highest exposure that is reasonably anticipated to occur at a site. • Chronic exposure • subchronic for construction worker • Risk Level: • NC: > Health Index (HI) of 1 by target organ, and • Carc: > Incremental Lifetime Cancer Risk (ILCR) of10-5 • 1 in 100,000 • Soil: Ceiling set at 10,000 PPM (1%)

  7. Programs / Clean-up Approval Process

  8. Applicable Media Soil Groundwater IndoorAir

  9. Applies to Sites Contaminated With: • Hazardous Substances (including Waste Oil) • Mixture of Hazardous Substances & Petroleum

  10. Applicable Site Types • Sites where these Routes of Exposure predominate • Ingestion • Soil • Groundwater • Skin Contact • Soil • Groundwater • Breathing • Outdoor Soil vapor & Dust • Indoor - Vapor Intrusion Image from Oregon State University Fact Sheet Diltamehrin, downloaded 6/14/2013 http://npic.orst.edu/factsheets/DeltaGen.html

  11. Applicable Site Types& Sites where these Exposure Scenarios predominate

  12. Not Applicable to Ecological Risk • when to conduct an ecological risk assessment • evidence of chem exposure to ecological receptors • visible physical evidence (sheens or neat product, etc.) • analytical data • PBTs in the top two (2) feet of soil • Receptors: surface water, sediment, wetlands, or biota • Consider runoff or other exposure pathways • Current or future potentialexposure

  13. Definitions A. Background Contaminants 6 B. Background Locations 6 C. Contaminant 7 D. Contaminant of Potential Concern(COPC) 7 E. Environmental covenant7 F. Exposure Pathway 7 G. Exposure Point 7 H. Exposure Point Concentration (EPC) 7 I. Hazard Index (HI) 7 J. Hazard Quotient (HQ) 8 K.Hazardous Substance 8 L.Hazardous Substance Site 8 M.Incremental Lifetime Cancer Risk (ILCR) 9 N.Neat material 9 P.Project Lead 9 Q.Public Water 9 R.Urban Fill 9

  14. Responsibilities

  15. RAGs are part of the basic remediation process

  16. Conceptual Site Model • Dynamic - Based on • all available site information • COPCs • Background Contaminants • Areas of Concern • Migration Pathways • Receptors (human / Eco) • Format • Concise Narrative • Figures /Tables • Understandable by Investigators and future owners Image from: Cox-Colvin & Associates Environmental Services, “EPA’s Revised Vapor Intrusion Guidance” downloaded 6/14/2013 from: http://www.coxcolvin.com/EPA_VI_Guidance.php

  17. Emergency Removals First Imminent Threats Containers Neat Material

  18. Site Investigations • RAGs - do not include investigation guidelines • Except for a few common issues…

  19. Sampling • Representative of site conditions • DQOs • RAG tables • Call DEP if matrix interference, etc., preclude detecting down to RAG

  20. Sampling Mercury Chromium Sample for hexavalent Chromium (+6) and trivalent chromium (+3), not total chromium. • Sample for Speciated mercury, not Total • Soil RAG for: • “Mercuric chloride and other inorganic mercury compounds”; • Indoor Air RAG for: • Elemental Mercury Image from Wikipedia, downloaded 6-18-2013: https://en.wikipedia.org/ wiki/Chromium

  21. Vapor Intrusion • VI section modified to incorporate lessons from • EPA Study • DEP Triage Study • For persistent compounds • vapors travel along preferential pathways • risk unless overlain >10’ low perm soil; • gas investigations: step out from the source to building; • If completed pathway, sample subslab/ perimeter gas • If these samples >10X RAGs, sample Indoor air

  22. Vapor Intrusion NEW! • For rapidly degrading compounds (petroleum): • Vapors need a continuing source & follow groundwater flow • Sample indoors only if gross contamination adjacent to building • Indoor Air Samples • analyze only for COCs • Compare results to RAGs table 2 • More: See VI guidance

  23. Exposure Point Concentrations • EPC = chem conc in medium at EP • E.g. Soil Conc. in in a residential yard. • Grab samples: • 95th upper confidence limit of the mean • or max w/ small datasets • Multi-Incremental Sampling • compositing samples within a grid-based Decision Unit • if DU = EP, then compared results to RAG. • If multiple DUs, then compare RAG to the 95th UCL of the mean of DUs NEW!

  24. Exposure Point Concentrations From: EPA, Supplemental Guidance to RAGS: Calculating the Concentration Term (OSWER, PB92-963373), May 1992

  25. Using the RAGs

  26. Target Risk Levels • Chronic exposure to RME • Risk Level: • NC: > Health Index (HI) of 1 by target organ, and • Carc: > Incremental Lifetime Cancer Risk (ILCR) of10-5 (=1 in 100,000)

  27. Background • “Background Contaminants”- not from site releases. • Naturally occurring (e.g. lead) or man-made (e.g. DDT). • Site activity may release naturally occurring elements that are not considered background (e.g. buried waste liberates arsenic). • Background Concentrations Policy: • not required to clean up background, (but owner should warn users) • If background is higher than a RAG, clean-up to background level • If background is less than RAG, clean-up to RAG level • Options to determine background • Site Specific Samples • Revised Typical Background Values for soil: Metals and PAHs in table 1 • Literature Values • Other scientifically based methods NEW!

  28. Background Study

  29. Soil BackgroundEvolving Background Locations

  30. Soil BackgroundEvolving Background Locations • 2010 • RAGs • 2011 Draft • RAGs • 2013 • RAGs • Rural Undeveloped • Metals • Rural Developed • PAHs • Rural • Metals • Rural • Metals, PAH • Urban Developed • PAHs • Urban • PAHs • Urban Fill • PAHs

  31. Soil Background

  32. Soil Background • Urban Vs Rural: DOT maps on Google Earth http://www.maine.gov/dep/gis/datamaps/statewide_layers/state_urban_compact_areas.kmz

  33. Soil Background • Urban Fill Image from Structure Magazine, “How Ground Improvement Can Eliminate the Need for Costly Deep Foundation System, downloaded 6-18-2013 from: http://www.structuremag.org/ article.aspx?articleID=1577

  34. Using the RAGs

  35. Exposure Pathways & Scenarios • RAGs include pathways and scenarios with the greatest potential to cause health impacts at Maine Sites. • Soil Exposure Pathway (Table 1) w/ (5) exposure scenarios • Indoor Air Exposure Pathway (Table 2); w/ (2) exposure scenarios • GroundwaterExposure Pathway (Table 3); w/ (2) exposure scenarios. • Which ones are applicable at your site?

  36. Exposure Pathways • Leaching to Groundwater • Residential • Park User • Commercial Worker • Excavation or Construction Worker

  37. Exclusion of Pathways • Unrestricted site use preferred • Include future use • ICs must meet UECA standards • Variances => Risk Manual • Significant site exposure pathway or scenario missing from RAGs • Seeking Variances to exposure assumptions

  38. Using the RAGs

  39. Using The RAG tables – (mg/Kg)

  40. Undertake Clean-up

  41. Using the RAGs

  42. Using the Risk Calculators UPDATED! • Excel Workbooks to calculate HI and ILCR from multiple contaminants • Soil • Water (2) • Air • Input EPC – the workbook does the rest http://www.maine.gov/dep/spills/publications/guidance/index.html#new_rag

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