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What is the Evidence for Long Term Stewardship (LTS) (vs. Stopping All Monitoring (SAM)) for the Vapor Intrusion Pathway ? * For EnviroForensics & Barnes.

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Presentation on theme: "What is the Evidence for Long Term Stewardship (LTS) (vs. Stopping All Monitoring (SAM)) for the Vapor Intrusion Pathway ? * For EnviroForensics & Barnes."— Presentation transcript:

1 What is the Evidence for Long Term Stewardship (LTS) (vs. Stopping All Monitoring (SAM)) for the Vapor Intrusion Pathway ? * For EnviroForensics & Barnes and Thornburg Webinar Nov. 19, 2014 by Henry J. Schuver, MS (Geology) DrPH (Epi) USEPA, ORCR, Wash. DC A Personal Public-Health Perspective - Does not Imply Agency Policy See: and 1 *Follows and evolved from: AWMA VI 2012 (MNA); AEHS EPA-Workshop 2014 (LTS as context); Battelle 2014 (comparison to other pathways/policies LTS) & AWMA VI 2014

2 Agenda Introduction Definitions Threshold criteria for LTS Data/evidence from: – Chemical VI – Radon VI Analogous (evidence-based) Polices Conclusions 2

3 Does this (simple) Conceptual Site Model [w/ variable categories 1-6] support LTS or Stopping All Monitoring (SAM)? Dissolved Contamination LTLT Diffusion Vadose zone Building zone of influence Wind effects Indoor Air Cracks Q soil Air streamlines Convection Top of capillary zone Water Table Stack effects Mixing in indoor air and inhalation Advection Diffusion Phase partitioning C gw to C soil gas Mod. from slide by M. Bolas, Ohio EPA, presented Jan ‘Low’ Chlorin. Chem. Vapor Source Term Contamination 1 2b 2a 2c Improving Assess. Methods & RE Sales 6 Changing Tox., Exposure Durations & Conc. Rn source 3

4 What is Long-Term Stewardship (LTS)? 1 LTS “applies to sites where long-term management of contaminated environmental media is necessary to protect human health” 1, Long-Term Stewardship: Ensuring Environmental Site cleanup Remain Protective Over Time” 4

5 What is SAM? ‘Stop All Monitoring’* Most ‘conventional’ VI monitoring is for an: – Anticipated Limited-duration ‘Assessment’ i.e., That can be used to Predict the future VI – & if Predict < std – Screen out (& never look back) Does evidence support the presumed goal of Stopping All* Monitoring (while VI-source remains) ? 5 *All = across All buildings (space) and All time

6 LTS ‘Threshold’ Criteria #1 1) Do VI sites have “contamination remaining” YES – VI sites are defined by the extent of contamination Buildings of concern for VI, are: – Overlying/proximate-to vapor-forming contamination i.e., VI-Source Media Conc. > generic screening values* So there is a Potential for inappropriate (VI) exposures 6 *e.g., > USEPA Regional Screening Levels (aka PRGs) based on empirical atten. data

7 Vapor Intrusion – Defined by Source Growing Awareness of Subsurface Vapor Sources - Especially in Non Drinking Water Areas If you look for low enough concentrations (DCE is ‘unique tracer’ of Groundwater) Proximity to a source appears to ‘determine’ its presence in indoor air (‘complete’ VI pathway) DCE – Dichloroethylene Source definition is a challenge - most of this plume found by indoor air

8 LTS ‘Threshold’ Criteria #2 2) Is the “management of contaminated environmental media necessary to protect human health”? YES Exposure factors (~10:1) Levels measured (e.g., up to ~2,000 ug/m3) ; – Combined with: Typical toxicology (lab-animal)-based estimates of Risks Correlations with human disease patterns 8

9 Disease Assoc. Support LTS or SAM?.. TCE plume (70 block) area: – ~2615 residents, 1090 births (‘78-02) 248 effects ~ ~ 1/4 – 117 Small for gestational age RR = 1.23 (95% CI = ) – 76 Low birth weight RR = 1.36 (95% CI = ) – 37 Term low birth weight RR = 1.68 (95% CI = ) – 15 Cardiac defects RR = 2.15 (95% CI = ) – 3 Conotruncal** defects RR = 4.91 (95% CI = ) * Also a similar paper on increases in adult cancers ** “abnormal formation of the outflow tracts of the heart” (RR) Rate Ratios relative to the rest of NY state (excluding NYC) “Conclusions: Maternal residence in both areas was associated with cardiac defects. Residence in the TCE area, but not the PCE area, was associated with low birth weight and fetal growth restriction.” Week 3: days from fertilization - “Primitive heart tube is forming” Week 4: days from fertilization - “The heart bulges, further develops, and begins to beat in a regular rhythm.” Do 1. How many other comm. (< #) ? 2. Short-term exp. concerns are real

10 LTS ‘Threshold’ Criteria #3 3) Are LTS activities “necessary to ensure that these sites remain [over the “long term”] protective of human health and the environment.” YES VI sources are often long-lasting (GW plumes) VI is unpredictably variable over time* both w/n: Short-term (~current conditions [say < 90 days]) Long-term (future conditions [say >90 days to 30 years] 10

11 Episodic Peaks Drive Exposure – Support SAM? 25 days (3.5%) present more exposure than the other 698 days Dr. Paul Johnson’s slide 20/48 - Note audio recording of presentation also available at: pdf 11 Chemical VI (TCE) at ASU’s ‘Sun Devil Manor’ 1. VI is variable in this house 2. Peaks drive (chronic) exposure

12 Some data from USEPA-ORD’s VI Research House with ~similarly Episodic behavior support SAM? Slide 7 of 22, audio also available at: pdf 12 Heated side of duplex 1. VI is variable in this house 2. Peaks drive (chronic) exposure

13 Is (simpler-)* Radon Intrusion Episodic? Looks to be in this Swedish home w/ unusual 1-day samples 13 * w/ a more constant & closer source, than most Chemical VI (e.g. ASU & ORD) Note, highest often not in winter Do these daily samples support SAM? 1. Rn-VI is variable in this house

14 14 Is Radon* Intrusion Episodic? Same MN home w/ Hourly, 2-, 7-, & 90-day (& yearly) samples Do these samples support Stopping all Monitoring? * w/ a simpler, more constant & closer source, than most Chemical VI) Would two samples from Winter help? 1. Rn-VI is variable in this house

15 Do these 1-yr samples support Stopping all Monitoring, after _ yrs? 15 Fig. from Steck in draft Lessons from Radon Studies … >4x variation in 17 years 1. Even 1-yr. long sample results are variable

16 Do differences & changes in Buildings support Stopping All Monitoring? 1) Design – Ground contact – Heating type, HVAC – Height, elevation, orientation … – Vegetation surrounding? 2) Construction 3) Condition 4) Occupants/Operation 5) Natural changes 6) Man-made changes 16

17 Who thinks EPA’s VI-db (GW) supports Stopping All Monitoring? 17 >100,000x variability, Includes both: Space (24 sites) & Time** **Using a few (short-term) Indoor Air samples per building

18 Does >10,000x* Variation in Sub-Slab to Indoor Air (w/n building) Attenuation … supports SAM? 18 Figure A. Box-and-whisker plot showing subslab soil gas CVOC attenuation factor distributions from EPA’s vapor intrusion database for individual sites with several buildings per site and subslab soil gas concentrations over 50 times “background” (U.S. EPA, 2012a) **Using a few (short-term) Indoor Air samples per building * Variability, Includes both: Space (12 sites) & Time**

19 * Extended ‘medians’ analysis for rest of EPA VI db showed similar results (by Dr. Wertz) Red & blue added to original slide by Dr. Helen Dawson, from AEHS March (Lowry Air Force Base, Colo.) ~100x More atten. in building than in subsurface * Does this Support SAM ?

20 Occupant-Operations Hourly Rn Variation 20 Fig. from Lessons from Radon Studies … Windows: Closed, Open EPA Rn testing procedures recommend Closed-house conditions – How many Chem. VI investigations/datasets do? Does this Support SAM? ~ 5x factor

21 Do Radon Studies illustrating effects of changes in building-structural factors – Support SAM? Steck 2007, see: ~ 5x change for both locations ~ 1/4x change for Stairwell Note, the difficulty of estimating changes in heating or air condition or adding porches; and also impacts to VI. Both man-made + natural changes: Earthquakes, Settling, Drying soils, Burrowing … 21 1-yr samples

22 Do evidence-based Policies for (simpler-) Radon support SAM? … NO USEPA (NAS-based) policy (1993) recommends: Sample every home (across space) Re-sample every 2 years (across time) Sample for a minimum of 2 diurnal cycles 48-hours 22

23 Policy Allowing Natural Attenuation to be part of (GW & Soil) Remedies Monitored Natural Attenuation – (MNA, EPA 1999)* – A major policy to allow & ensure natural processes are ‘safe’ – With “adequate monitoring of a natural attenuation remedy to ensure with a high degree of confidence that potential receptors will not be impacted” – Is not a ‘no action’ or ‘walk away’ remedy – MNA is effectively: On-going assessment - to ensure on-going protection *OSWER Dir P for CERCLA, RCRA, UST

24 NRC panel/report on managing complex GW sites* support SAM? Panel reported increasing use of controls – that would ‘of course’ include continued ground- water monitoring to be sure there would be no inappropriate exposures And when asked (in Q/A**) If that included on-going monitoring for VI it was … … – Agreed it would So: No, NRC does Not support SAM for VI » i.e., VI is one pathway assoc. w/ GW plumes & needs LTS 24 * Alternatives for Managing the Nation’s Complex Contaminated Groundwater Sites, NRC 2012 ( ** Battelle Chlorinated Remed. Conf. 2014

25 In Summary Vapor Intrusion meets: – The three ‘threshold’ criteria for Long Term Stewardship – Contamination remains (proximate to receptors) – Management is needed to Protect human health – Management/activities are needed over the long term Given the nature & scale of changes possible: – LTS is as appropriate (for VI), or even more so – Than for any other (current) pathway for exposure 25

26 While VI Contamination Remains … & for GW plume-sources could be 20, 30, even 50 +? years Be a Good Steward – Ensuring no* (VI) Exposures e.g., » On-Going Monitoring at an frequency appropriate for the: Shortest exposure durations of concern Variability of intrusion (incl. episodic peaks) Concentration & Mass of Contamination remaining; Or » Ongoing Prevention/Control of exposures [needs separate discussion] Not acting as if the goal is to Stop All Monitoring** which: Relies on Un-Monitored Natural (vapor) Attenuation As the only protection 26 *inappropriate **Is there any, or a even a simple majority, or 95% of, evidence to support that?

27 Acknowledgements To those who have designed &/or collected some of the most important (& highest-quality) evidence for assessing/managing VI risks: – D. Steck – P. Johnson – B. Schumacher – C. Lutes – C. Holton – T. McAlary, H. Dawson, W. Wertz, I. Hers 27

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