Volatilization to Indoor Air Pathway (VIAP) and Vapor Intrusion (VI) What it is and What s up Matthew Williams Vapor Intrusion Specialist Remediation and Redevelopment Division Phone: (517)284-5171 Email: williamsm13@michigan.gov MI AHMP Annual Conference March 29, 2018
The Pathway Volatilization to Indoor Air Pathway (VIAP) Pathway describing the inhalation of hazardous substance vapors volatilizing from a vapor source and migrating to indoor air. PROPOSED - The proposed generic criteria addressing this pathway are called volatilization to indoor air criteria ( VIAC ) 2
Vapor Source A concentration above which a hazardous substance may form vapors or consist of vapors that have the potential to migrate and cause an unacceptable risk to human health Groundwater Soil NAPL (at or above the water table surface) Vapor *USEPA, 2012 3
Vapor Source Outside Structure Vapor Intrusion The process by which hazardous substances migrates as vapor through the subsurface into the indoor air VI thru cracks in the foundation slab Utilitie s VI through floors and wall cracks 4 Groundwater that is a source of vapors *EDR
Vapor Source Inside Direct Volatilization to Indoor Air Hazardous substances that, based on the location, will volatilize directly into the structure without migrating through soil Potential VIAP problem but NOT VI 5
Shallow Groundwater in MI Depth to GW < 10 feet *Data from MSU Extension 2015
Foundations in the Midwest New Construction Type of Foundations Single Family Midwest *US Census Data for the Midwest 7
PVI vs CVI There are differences Petroleum vapor intrusion (PVI) is a subset of VI that deals exclusively with releases from a petroleum source Chlorinated vapor intrusion (CVI) is a subset of VI that deals with chlorinated hydrocarbons and includes mixed releases that may also contain a petroleum source PVI CVI *ITRC, 2014 8
Distance Vapors Will Travel Lateral Inclusion Zone PVI 30 CVI 100 The horizontal distance beyond a vapor source that may make a property or structure vulnerable to the migration of vapors 9 *Modified from ITRC, 2014
Distance Vapors Will Travel Impact of the Lateral Inclusion Zone Source of vapor in groundwater Lateral inclusion zone for groundwater 10
Variation in Vapor Concentration May Change Aerially over Time *Luo 2008, Luo et al. 2009 11
Variation in Vapor Concentration From a Single Monitoring Location *P.C. Johnson, 2014 12
Indoor Air Expect Variability Hourly, Daily, Seasonally, Buildings Field observations and measurements demonstrate that indoor air concentrations can exhibit significant temporal variation within a day and between days and seasons in an individual residential building. (EPA 2012a; Holton et al. 2013ab) Can span at least an order of magnitude and often more 13
Odor vs Unacceptable Risk Odor Threshold 1 (ppmv) SKUNK (MERCAPTANS) 0.001 Odor Threshold 1 (µg/m 3 ) Minimal Risk Levels (MRLs) Chronic (µg/m 3 ) Intermediate (µg/m 3 ) Acute (µg/m 3 ) BENZENE 4.68 14,951 3.3 19.17 28.75 TETRACHLOROETHYLENE (PCE) 4.68 31,745 41 41 41 TRICHLOROETHYLENE (TCE) 21.4 115,009 2.1 2.1 -- ATSDR identified exposure times: Acute: 1-14 days Intermediate: >14-364 days Chronic: 365 days and longer 1 Leonardos, Gregory; Kendall, D. & Barnard, N. 2012. Odor Threshold Determinations of 53 Odorant Chemicals 14
Toxicological Perspective Some substances may cause an effect after a single or very short exposure: Developmental toxicants Acute or Intermediate MRLs (ATSDR) Short-term RfCs (US EPA) A single exposure at a critical time is sufficient to produce an adverse effect 15
Exposure has Occurred Don t have 30 More Years Exposure has likely occurred for an extended period of time Potential short term health effects may include Developmental effects - Spontaneous abortion, congenital heart defects, central nervous system defects, and small birth weight, developmental abnormalities Can affect male - Decreases in sex drive and sperm quality Can vary depending on level of exposure and chemical involved 16
Impacts How We Investigate New Realities Concentrations may be present that need to be addressed quickly Low concentrations make field screening tough and require extra care Acute situations may look normal Collection of data Multiple lines of evidence are important High variability over short periods of time is expected How and where we sample 17
Impacts How We Investigate New Realities Can t provide bottled air Evacuation may be warranted One type of mitigation may not be appropriate for all structures Presumptive mitigation doesn t mean no data Need to understand your conceptual site model 18
Multiple Lines of Evidence Very Important *P.C. Johnson, 2014 19
Importance of Good Information New Reality Conceptual Site Models are important Utilize and understand Multiple Lines of Evidence By themselves: Soil is NOT a good predictor of VI Sometimes groundwater is not Often indoor air isn t 20
DEQ and DHHS are Partners A reminder DEQ and DHHS have a data sharing agreement DHHS and Local HD completes their own analysis of the data and may take its own response and/or notice actions 21
What s Up Interim Action Screening Levels LISTSERV dated August 07, 2017 Collaboratively developed by DHHS and DEQ Media Specific Soil, Groundwater Vapor 22
Interim Action Screening Levels 29 Hazardous Substances Intended to assist with risk evaluation by: Determining if potentially unsafe levels of chemicals are present in the indoor air; Determining whether interim action to reduce potential exposure is needed; and If interim action is needed, assist in determining how quickly those actions should be completed Scientifically-based Media specific for both residential and nonresidential 23
Screening Levels Interim Action vs Time-Sensitive Recommended interim action screening levels (RIASLs) initiated expeditiously to mitigate the exposure(s) Recommended time-sensitive recommended interim action screening levels (TS RIASLs) immediate actions such as mitigation and/or evacuation 24
Interim Action Screening Levels Use by RRD and DHHS RRD: Notification of VIAP sites to DHHS Interim response decisions Emergency action decisions DHHS and LHD: Evacuation decisions Initial evaluation of whether people can stay in buildings until mitigation is completed Initially evaluate short/long term health considerations; education 25
What s Up Proposed Rules Tiered Approach For the VIAP Common in modern risk based guidance Intended to promote: Efficiency Better characterization Other key features: Self implement through VI Tier 3A Flexible 26
What s Up Proposed Rules Tiered Approach For the VIAP VI Tier 1 VI Tier 2 VI Tier 3A 27 Generic Screening Level *University of Wisconsin Facility specific inputs to establish Generic Unrestricted Residential Criteria *images from vastree.com Facility specific inputs to establish Generic Restricted Criteria
Depth to Groundwater Single Parameter Sensitivity Analysis Hazardous Substance Benzene Tetrachloroethylene Trichloroethylene CAS # 71432 127184 79016 Depth to GW µg/l µg/l µg/l <3m 1 1.5 0.073 Just >3.0m 14 96 6.1 5m 18 130 7.8 10m 27 200 12 The deeper the groundwater is, the more a hazardous substance is able to diffuse before reaching a structure 28
Soil Type Single Parameter Sensitivity Analysis Hazardous Substance Benzene Tetrachloroethylene Trichloroethylene CAS # 71432 127184 79016 UNITS µg/kg µg/kg µg/kg Sand 1.7 6.2 0.33 Loamy Sand 11 41 2.3 Sandy Loam 33 120 7.0 Loam 120 450 27 Larger particles (e.g., sand) means more pore space and easier migration of soil vapors 29 29
Proposed Rules Are a Solution Current Application of Generic Criteria GVIIC/SVIIC Part 201 Contaminated Facilities Part 213 Open LUST Releases Limitations: #1 Depth to groundwater < 3m GVIIC does not apply #2 Presence of a sump 30
Current Part 201 Generic Criteria Inhalation Pathway Current Generic Criteria Under Part 201 SVIIC - Soil Volatilization to Indoor air Inhalation Criteria GVIIC - Groundwater Volatilization to Indoor air Inhalation Criteria When the generic assumptions are not met, further evaluation is necessary Site-specific evaluation 31
Current Part 201 Generic Criteria Do Not Apply Groundwater (Rule 14(2)): Structure present (or planned) which does not have a concrete block or poured floor and walls Groundwater is within 3 meters of the ground surface A sump present Soil (Rule 24(2)): Structure present (or planned) which does not have a concrete block or poured floor and walls A sump present Presence of Non Aqueous Phase Liquid Other 32
DEQ Assistance Current vs Proposed 33 Current Site-specific requests Total Submissions: > 425 Both current and proposed allow the opportunity to propose alternate approaches Proposed Facility-specific Similar to interim action site-specific evaluations Ability to self implement Site-specific Alternative options Requires DEQ approval
What s Up - Site-Specific Criteria DEQ Providing Assistance Required if generic criteria do not apply Optional NOT a requirement Want to capture or consider: Multiple soil types present Different soil parameters Greater air exchange Alternate approach Evaluating petroleum Evaluating NAPL New method or model 34
What s Up Training Opportunity How to Investigate VIAP
VIAP Workshop Spring 2018 What will be covered 1. Investigative Planning 2. Area Wide Investigation 3. Building Specific Investigation 4. Mitigation Establish the Area of Interest Identify the structures to focus on Collect Multiple Lines of Evidence Prevent further exposure *From www.hyde-env.com, 2017
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