epa update on vapor intrusion - newmoa...us epa vapor intrusion database: attenuation factor...
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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
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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
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Vapor Intrusion PathwayPotential ScenariosPotential Scenarios
Generic CSM
3T. McAlary
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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EPA VI Guidance (Nov. 2002) Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils WashingtonAir Pathway from Groundwater and Soils.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)
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JE Model (2003)
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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”
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Site-specific modeling to identify “most-likely-to-be-impacted”Building air measurements (sub-slab, crawlspace, indoor)
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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
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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?
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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)
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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
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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
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PartnersDOE DOD EPA
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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
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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
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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.
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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.
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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
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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
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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
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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
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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
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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
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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.
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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
ewel
lPr
ecis
ion
Jack
son
LAFB
e Vi
llage
ockw
ood
l MA
DEP
ffet M
CH
unt H
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
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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
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Sub-Slab Concentration (ug/m3)Alpha = 0.01New Data 1.0E-07
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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
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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
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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
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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
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Chlorinated hydrocarbons: 97%Petroleum hydrocarbons: 3%