EPA Update on Vapor EPA Update on Vapor Intrusion

Presented By: Helen Dawson Ph DPresented By: Helen Dawson, Ph.DUS EPA, Region 8, Denver, CO

Vapor Intrusion Workshop Vapor Intrusion Workshop –– September 2008September 2008

Presentation OutlinePresentation Outline

Update on EPA VI GuidanceBackground (Nov. 2002, Draft VI Guidance)Current (2008) StatusCurrent (2008) Status

Update on EPA VI DatabaseChanges in database from 2002 to 2008gDatabase contentsUses of the database

2

Vapor Intrusion PathwayPotential ScenariosPotential Scenarios

Generic CSM

3T. McAlary

EPA VI Guidance BackgroundBackground

EPA VI Guidance (Nov. 2002) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils WashingtonAir Pathway from Groundwater and Soils. Washington, D.C.: Office of Solid Waste and Emergency Response. (www.epa.gov/correctiveaction/ eis/vapor/complete.pdf)

Tiered approach

EPA VI Database (Appendix F of 2002 VI Guidance)

JE M d l (2003)

4

JE Model (2003)

EPA VI Guidance Background Tiered ApproachTiered Approach

Tiered approach to screening sites & buildings

Groundwater Soil Gas Subslab Indoor Air

1 - Primary (Q1, Q2, Q3):Identify potential for indoor air concerns and screen for obvious problems

2 - Secondary (Q4, Q5):Compare subsurface data to generic and semi-site specific screening levels

Generic screening levels based on limited data set of empirical attenuation ffactorsSemi-site specific screening levels derived from JE model attenuation factors

3 - Site-Specific Pathway Assessment (Q6):Si ifi d li id if “ lik l b i d”

5

Site-specific modeling to identify “most-likely-to-be-impacted”Building air measurements (sub-slab, crawlspace, indoor)

EPA VI Guidance BackgroundGeneric Soil Gas & Groundwater Screening LevelsGeneric Soil Gas & Groundwater Screening Levels

Select indoor air target screening levelSelect indoor air target screening level

Apply generic attenuation factors:

AF = 0.1Shallow soil gas (and subslab) screening level is 10 times indoor air target screening level. AF = 0.1

Deep soil gas screening level is 100 times indoor air target

AF = 0.01

Deep soil gas screening level is 100 times indoor air target level. AF = 0.01

Groundwater screening level is the aqueous concentration corresponding to a soil gas concentration 1000 times

AF = 0.001p g g m

greater than the indoor air target level. AF = 0.001

Generic attenuation factors (AF) based

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Generic attenuation factors (AF) based on limited vapor intrusion data

2008 Perspective on EPA’s 2002 VI GuidanceEPA s 2002 VI Guidance

Outdated:

Framework for screening out sites2002: Sequential use of single media/lines of evidence2008: Multiple lines of evidence (ITRC 2007)2008: Multiple lines of evidence (ITRC, 2007)

Generic screening levels for subslab & soil gas2002: Subslab attenuation factor = 0.1; 2008?2002: Soil gas attenuation factor = 0.01; 2008?

7

2008 Perspective on EPA’s 2002 Guidance (cont )EPA s 2002 Guidance (cont.)

Still Useful:

Approaches for individual media (each line of evidence)Approaches for individual media (each line of evidence)

Groundwater generic attenuation factor2002 generic value 0 0012002 generic value 0.0012008: 0.001 captures majority of observed data

(US EPA VI Database 2008)Subslab generic attenuation factorSubslab generic attenuation factor

2002 generic value 0.12008: 0.1 captures majority of observed data

(US EPA VI Database 2008)

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(US EPA VI Database 2008)

EPA VI Guidance Current (2008) StatusCurrent (2008) Status

Endorse multiple lines of evidence” approach:E.g., ITRC. January 2007. Vapor Intrusion Pathway: A Practical Guide (http://www itrcweb org/gd VI asp)Practical Guide (http://www.itrcweb.org/gd_VI.asp)Provides flexible framework for assessing VI pathwayDescribes a variety of available tools

9

Interstate Technology & Regulatory CouncilRegulatory Council

G dLatest Vapor Intrusion Guidance:

ITRC. January 2007. Vapor Intrusion Pathway: A PracticalIntrusion Pathway: A Practical Guidehttp://www.itrcweb.org/gd_VI.asp

flexible framework

variety of toolsHost Organization

ITRC Member State

multiple-lines of evidenceHost Organization

Federal

10

PartnersDOE DOD EPA

Multiple Lines of Evidence Investigative ApproachInvestigative Approach

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Why is a multiple lines of evidence approach needed?approach needed?

Sub-Slab (TCE ug/m3)Spatial (and temporal) variability

Indoor Air (1,1-DCE ug/m3)

Groundwater (1,1-DCE ug/L)

1108.2

29

23

73

120

37

11

515 4

31

18

15

1108.2

29

23

73

120

37

11

515 4

31

18

15

( , g )

17

30

15

22

9.3

12

8.4

515.413

15

30

15

22

9.3

12

8.4

515.413

15

189

7.120382233

7.120382233

12

316.6469122 6.6469122

EPA VI Guidance Current (2008) Status cont’dCurrent (2008) Status, cont d

Provide supplemental technical informationDatabase of vapor intrusion observationsBackground levels of contaminant in indoor airBackground levels of contaminant in indoor air Conceptual Site Model - updated and expandedJohnson & Ettinger Model - improvements in inputsg p p

13

Vapor Intrusion DatabaseVapor Intrusion Database

Database and technical documentIndoor air concentrations paired with concentrations in:

GroundwaterGroundwater Soil gas (exterior to bldg)SubslabCrawlspaceCrawlspace

Draft version Currently available for review http://iavi.rti.org(register for access to database, and click on “Other Documents” for the “Preliminary Evaluation of Attenuation Factors”)the Preliminary Evaluation of Attenuation Factors )

Final version in late 08/early 09

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Background Indoor Air ConcentrationsConcentrations

Compilation of background indoor air concentration studies in North American residences

Compiles recent data: 1990 – 2005Compiles recent data: 1990 – 2005Provides statistical distribution of concentrations

Draft version available for review late 08Final version available 2009

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Conceptual Site ModelConceptual Site Model

Theoretical overview of vapor intrusion processes3D model scenariosFactors affecting vapor migrationFactors affecting vapor migrationSources of temporal and spatial variabilityInfluence of building on subsurface concentrationsg

Draft version available for review late 08Fi l i il bl 2009Final version available 2009

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J&E Model UpdateJ&E Model Update

Technical update will provide improved model spreadsheets More accurate ranges for inputs Ensures compatibility of inputsEnsures compatibility of inputs

Draft version late 2008Final version first half of 2009

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Non-Residential SettingsNon-Residential Settings

US EPA Nov. 2002 Draft VI Guidance:OSHA standards apply in workplaces where workers are handling hazardous chemicals (e.g., manufacturing facilities) similar to or different from those in subsurface contamination as well as other workplaces such asin subsurface contamination, as well as other workplaces, such as administrative and other office buildings where chemicals are not routinely handled in daily activities.However, the guidance recommends that regional or State authorities notify

f ilit of the potenti l fo the po int ion p th to e h da facility of the potential for the vapor intrusion pathway to cause a hazard and suggest that they consider any potential risk that may result.

Many state agencies:Many state agencies:Require that occupational exposure be based on risk-based screening values and not OSHA standards when workplace-related vapors are not expected because the hazardous vapor-forming chemicals are not being used in the building being investigated

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used in the building being investigated.

Update on EPA’s Vapor Intrusion DatabaseEPA s Vapor Intrusion Database

2002: US EPA draft vapor intrusion guidance releasedKey feature of guidance – generic attenuation values (Tier 2 screening of concentrations in subsurface media) based on statistical analysis of a limited number of observations fromstatistical analysis of a limited number of observations from a few sites (U.S. EPA, 2002, Appendix F).

20032003EPA met with a team of consultants and state regulators to lay out content, design, and quality assurance requirements for an expanded database

2004 - 2006EPA held a series of national workshops to provide a forum to share d t d i f i t f i t i it

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data and experiences from a variety of vapor intrusion sites. Data also gathered from state regulators and EPA’s Regional offices.

AcknowledgmentsAcknowledgments

Ian HersGolder and Associates, Vancouver, B.C., Canada

Robert TruesdaleRTI International, Research Triangle Park, NC, USA

William WertzNew York State Department of Environmental Conservation, NY, USA

Todd McAlaryGeosyntec Consultants, Toronto, Ontario, Canada

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Changes in database from 2002 to 2008from 2002 to 2008

Sites Buildings Attenuation FactorsAttenuation Factor Type 2002 2008 2002 2008 2002 2008

groundwater to indoor air 15 36 73 658 266 1,058

soil gas to indoor air 4 17 8 130 16 237

b l b i d i 1 15 9 424 86 1 584subslab to indoor air 1 15 9 424 86 1,584

crawlspace to indoor air 1 4 4 11 40 110Totala 15 41 73 913 408 2 989Total 15 41 73 913 408 2,989

a Total numbers of sites and buildings in the database are less than the totals of individual attenuation factor typesbecause some sites and buildings have more than one type of attenuation factor.

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Database ContentsDatabase Contents

15 States

41 Sites

21 Chemicals97% chlorinated hydrocarbons3% petroleum hydrocarbons

913 Buildings913 Buildings85% residential10% institutional or commercial5% multi-use (residential and non-residential)

2989 Paired indoor air and subsurface concentration measurements35% paired groundwater and indoor air measurements8% paired soil gas and indoor air measurements

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53% paired subslab and indoor air measurements4% paired crawlspace and indoor air measurements

Summary of Compiled DataSummary of Compiled Data

Soil Multi-UseV. Coarse >200

4

4 8

2 3 2

80%

90%

100%Soil Multi Use

Non-Residential

V. Coarse >200

10-50

2560%

70%

Coarse

3734

31

30%

40%

50%

Groundwater

Database FieldsDatabase Fields

Site information (hydrogeologic setting, vapor source type)

Building characteristics (bldg use, foundation type, depth to source)

S il t ( d ilt t )Soil type (sand, silt, etc.)

Chemical

Sampling and analysis information (sample location collectionSampling and analysis information (sample location, collection period, analytical method)

Indoor air paired with groundwater, sub-slab, soil gas, and/or crawlspace samplescrawlspace samples

Calculated Attenuation Factor (AF)

AF = Cair/Csubsurface

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air subsurface

AF < 1.0

Spreadsheet DatabaseSpreadsheet DatabaseUS EPA Vapor Intrusion Database: Attenuation Factor Analysis

Site Name: All Sites1.E+04

m3) EPA Data (IA > RL)

ChemName: All ChemicalsChem Type: All Chemical TypesSoil Texture Code: All Soil TexturesSoil Type: All Soil TypesBldg Use: All Building Uses

1 E 01

1.E+00

1.E+01

1.E+02

1.E+03

r Con

cent

ratio

n (u

g/m

EPA Data (IA < RL)

Alpha = 1.0

Alpha = 1E-1

Alpha = 1E-2

Alpha = 1E-3

Foundation Type: All Foundation Types

Subsurface Media: Groundwater Vapor (ug/m3)

Stats EXCEL KMStatsMi 3 3E 07 3 3E 07

1.E-03

1.E-02

1.E-01

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Indo

or A

i

Alpha = 1E-4

Alpha = 1E-5

Groundwater Vapor (ug/m3)

Min 3.3E-07 3.3E-075% 3.6E-06 3.3E-06

25% 1.6E-05 1.4E-0550% 8.8E-05 8.7E-0575% 4.0E-04 4.0E-0495% 2.4E-03 2.4E-03Max 7.4E-02 7.4E-02

1.E-03

1.E-02

1.E-01

1.E+00tio

n Fa

ctor

EPA Data (IA > RL)

EPA Data (IA < RL)

1.E-03

1.E-02

1.E-01

1.E+00

ion

Fact

or

EPA Data (IA > RL)

EPA Data (IA < RL)

1.0E-03

1.0E-02

1.0E-01

1.0E+00

Fact

or Max

95th %

Mean 1.2E-03 1.2E-03StdDev 6.7E-03 6.7E-0395UCL 8.9E-04 1.9E-03

Count All 218 218Count D 201

Count ND 17 1.E-07

1.E-06

1.E-05

1.E-04

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Atte

nuat

1.E-07

1.E-06

1.E-05

1.E-04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04

Atte

nuat

1.0E-06

1.0E-05

1.0E-04

1.0E 03

Atte

nuat

ion 50th %

5th%

Min

25

Filter Criteria Counts Visible Data--> 910Site, Chemical, Soil, and Building Filters Selected DataCS Filters IA FiltersGW Filters SS Filters SG Filters

Groundwater Vapor (ug/m3) Indoor Air Concentration (ug/m3)1.0E-07

QA ChecksQA Checks

Sampling design reviewedRepresentative samples?Concurrent paired samples?

Sampling and analysis QA/QC reviewedEPA TO-14, TO-15, TO-17, 8260BEPA QA/QC protocols

Indoor survey reviewed (if available)

Data consistency evaluated (if multiple chemicals reported)

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Data entry validation

Handling Data Below Reporting LimitsData Below Reporting Limits

All data below reporting limits flagged

Subsurface data < RL excluded from statistical analysis

AF = Cair/Csubsurface

Indoor air data < RL included in statistical analysis usingIndoor air data < RL included in statistical analysis using Kaplan Meier method (Helsel, 2005)

Kaplan Meier: robust non-parametric method capable of p p pconsidering data sets with substantial proportions of data below reporting limits, as well as multiple reporting limits and J-qualified values.

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J qualified values.

How can you use the Vapor Intrusion Database? Vapor Intrusion Database?

Provide an empirical line of evidence to aid in decision-making regarding site characterization, remediation, and risk managementrisk management.

Compare site data to a compiled data set of “proven” vapor intrusion sites.p

Evaluate the relationships between vapor source concentrations, indoor air concentrations, and site conditions.

Develop screening levels.

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Groundwater-to-Indoor Air AttenuationIndividual Site Box Whisker PlotsIndividual Site Box Whisker Plots

Groundwater AF for Individual Sites

1.0E-02

1.0E-01

1.0E-05

1.0E-04

1.0E-03

Gro

undw

ater

AF

1.0E-07

1.0E-06

0 X

BK

G

Alle

po

ings

PCE

BP

Site

CD

OT

Dav

is

au C

laire

Endi

cott

sh W

ater

Lens Gra

nts

amilt

on-

ndst

rand

Tri S

tate

Hop

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lPr

ecis

ion

Jack

son

LAFB

e Vi

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ockw

ood

l MA

DEP

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CH

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olly

ain

View

apid

City

Red

field

SCM

-la

ndvi

lle

Staf

ford

win

s In

n

ncas

ville

Wal

l

est S

ide

pora

tion

Z C

A B

ay

> 50 Bill

i

Ea

Fres Ha

Sun

Har

cros

/ H P J

Lake

side Lo All

Mof

Mou

Mou

nta

Ra S

Cor

t T w Un

We

Cor W

Z

29

Compare Site Data to Database Compare Site Data to Database

Allows for inclusion of spatial and temporal variability in the decision-making process.

Indoor Air vs Sub-Slab Concentration

1.E+03

1.E+04

g/m

3)

1 0E 02

1.0E-01

1.0E+00

M

1 E+00

1.E+01

1.E+02

Con

cent

ratio

n (u

g

1.0E-04

1.0E-03

1.0E-02

nuat

ion

Fact

or

Max

95th %

50th %

5th%

1.E-02

1.E-01

1.E+00

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Indo

or A

ir

EPA DataAlpha = 1.0Alpha = 0.1Alpha = 0.05Alpha = 0.02Al h 0 01

1.0E-06

1.0E-05Atte

n

Min

30

Sub-Slab Concentration (ug/m3)Alpha = 0.01New Data 1.0E-07

Groundwater-to-Indoor Air AttenuationAttenuation

Chemical

1.0E-02

1.0E-01

Building Use

1.0E-02

1.0E-01

M

Soil Type Under Slab

1.0E-02

1.0E-01

Max

1.0E-04

1.0E-03

ound

wat

er A

F

Max

95th%

50th%

1 0E 05

1.0E-04

1.0E-03

Gro

undw

ater

AF

Max

95th%

50th%

5th%

1.0E-04

1.0E-03

roun

dwat

er A

F

Max

95th%

50th%

5th%

1 0E 07

1.0E-06

1.0E-05Gro 5th%

Min

1.0E-07

1.0E-06

1.0E-05

al al

G 5t %

Min

1.0E-07

1.0E-06

1.0E-05Gr

Min

1.0E-07

All

CH

Cs

11D

CE

TCE

PCE

cis1

2DC

E

All

PHC

s

Res

iden

tia

Com

mer

cia

Fine

Coa

rse

V.C

oars

e

31

Exterior Soil Gas vs SubslabExterior Soil Gas vs Subslab

1 E+05

1.E+04

1.E+05

m3)

1.E+03

entr

atio

n (u

g/m

Subslab > Soil Gas

1.E+02

ubsl

ab C

once

1.E+00

1.E+01

1 E 00 1 E 01 1 E 02 1 E 03 1 E 04 1 E 05 1 E 06 1 E 07 1 E 08

Su

32

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Soil Gas Concentration (ug/m3)

H. Dawson

Summary of EPA’s Vapor Intrusion DatabaseEPA s Vapor Intrusion Database

42 Total sites GW: Groundwater (36 sites)SG: Soil gas (14 sites) 1.0E-01

1.0E+00

1.0E+01

Max

SS: Subslab (19 sites)CS: Crawlspace (4 sites)

1 0E 04

1.0E-03

1.0E-02

tenu

atio

n Fa

ctor 95th%

50th%

5th%

3,162 paired measurementsSS: 50%, GW: 39%, SG: 8%, CS: 3% R id ti l 86 %

1.0E-06

1.0E-05

1.0E-04

Att

Min

Residential: 86 %, Commercial: 9 %Multi-use: 5%Chlorinated hydrocarbons: 97%

1.0E-07

GW

> R

L

SG >

RL

SS >

RL

CS

> R

L

33

Chlorinated hydrocarbons: 97%Petroleum hydrocarbons: 3%