Vapor Intrusion Risk Pathway Vapor Intrusion Risk Pathway Regulatory Updates & Practical StrategiesRegulatory Updates & Practical Strategies

Blayne HartmanIndependent Consultant

760-925-7206www.handpmg.com

Kennedy-Jenks WebinarKennedy-Jenks WebinarJune 2010June 2010

What Is Vapor Intrusion?What Is Vapor Intrusion?

Key Criteria Controlling Assessment:– Risk level (1 in 10,000? 100,000? 1,000,000?)– Toxicity of Compounds– Exposure Factors (time, rates, ventilation)

Why Do You Care About VI?Why Do You Care About VI?(Risk Often More Perceived Than Real)(Risk Often More Perceived Than Real)

• Health & Safety of Occupants

• EPA, ITRC, & State Guidances

• ASTM New Phase 1 Standard

• Attorneys & Citizen Groups

• Future Liability

When to Worry About VI?When to Worry About VI?

• If VOC Contamination & Structures Exist: – Laterally within 100’ (EPA, DTSC)– Vertically Within 100’ (EPA, DTSC)– NY: No Limits!!!

• Complaining Occupants

• Structures With Odors, Wet Basements

• Sites With Contamination & Future Use

• Attorneys & Communities

• Even Animals, Fruits, Vegetables

EPA-OSWER Draft GuidanceEPA-OSWER Draft Guidance

• Tier 1: Primary Screening– Q1: VOCs present?– Q2: Near buildings?– Q3: Immediate concern?

• Tier 2: Secondary Screening– Q4: Generic screening– Q5: Semi-site specific screening (alphas from charts &

tables)

• Tier 3: Site-Specific Pathway Assessment – Q6: Indoor air (and/or subslab)

Newest Changes (2010?) Newest Changes (2010?) EPA OSWER VI GuidanceEPA OSWER VI Guidance

• Tier 1: Primary Screening– Q1: VOCs present?– Q2: Near buildings?– Q3: Immediate concern?

• Tier 2: Source Screening– Generic screening using near-source samples

• Tier 3: Pathway (Building) Assessment– Multiple lines of evidence (sg & gw)– Must go inside???

EPA Guidance UpdatesEPA Guidance Updates

• Fed EPA (OSWER & Superfund)– Modeling no longer an exit– Moving to sub-slab & indoor air– 7 to 30 day indoor air sampling period– Att factor of 0.1 for SG & 0.001 for GW– Decision matrix?

• EPA-OUST: Guidance for HCs by 2012– Exclusion criteria by Fall 2010

OH 9-07 9

Well above level of concern

Around level of concern

Well below level of concern

Well above level of concern

Interior sampling or mitigation

Possible vadose source; Interior

sampling or mitigation

Possible vadose source; Interior

sampling or mitigation

Around level of concern

Interior sampling or mitigation

Interior sampling or mitigation

Possible vadose source; Interior

sampling or mitigation

Well below level of concern

Consider

geologic setting1, verification sampling in

select locations

Consider

geologic setting1, verification sampling in

select locations

NFA unless nearby property

has unacceptable risks (verification,

monitoring)

Concentration in GroundwaterC

on

cen

trati

on

in

So

il G

as

DRAFT Exterior Decision

Matrix

1 Review subsurface startigraphy, depth to water, to determine presence, integrity, effectiveness of geologic barriers to vapor migration.

Allowable Benzene in GW Allowable Benzene in GW 1e-6 risk1e-6 risk

•New OSWER Guidance:

0.31 ug/m3/0.001 = 0.31 ug/L/0.2 = 1.5 ug/L

• Robin Davis’ Exclusion Value: 1000 ug/L

~700 times lower than database suggests!!~700 times lower than database suggests!!

Allowable Soil Gas LevelsAllowable Soil Gas Levels(Benzene 1e-6 Risk, residential)(Benzene 1e-6 Risk, residential)

State Alpha 1/Alpha Risk Based Level (ug/m3)

EPA Now 0.002 500 155

EPA 2012? 0.1 10 3.1

CA 0.002 500 42

NJ (Subslab) 0.05 200 60

MO 118,000

TN 0.0013 780 2,414

CT 0.1 10 192

State Guidance UpdatesState Guidance Updates

• States With Recent Guidances/Policy

– OR, OH, MT, WA

• States Rethinking Guidances/Policy

– IL, NJ, MA, MO, TN, ME, CA

CA AgenciesCA Agencies

• CA-DTSC (& LA-RWQCB)– Soil Gas, VI, & Mitigation “Advisory”– CHHSLs (thanks to OEHHA)

• EPA Region 9

– Follows the EPA Draft VI Guidance– Adopted Region 3 Screening Levels

• SF-RWQCB

– ESLs include aliphatics!

• Central Valley Boards – Want Residential Criteria Applied Regardless of Site Use

Uh-Oh Uh-Oh

I wanted to provide a heads up that R2 (SF) is poised to modify its Environmental Screening Levels (ESLs) with respect to the vapor intrusion pathway ... the consequence of this change would be much lower groundwater ESLs for this pathway (20 to 30x lower for most VOCs and over 200x lower for biodegradable VOCs such as BTEX) ... details below ... cheers

E-mail received on 9/15/09:

ITRC VI GUIDANCEITRC VI GUIDANCE

• Practical How-to Guide

• Stepwise Approach

• Investigatory Tools (Toolkit)

• Thorough Discussion of Mitigation

• Scenarios Document

• Three Training Dates in 2010

The Net Widens: The Net Widens: ASTM VI StandardASTM VI Standard

• Focus on Property Transactions

• Prescriptive Screening Distances

• No RBSLs (RBC)

• No Assessment Recommendations

• Legal Standards

• Mitigation

• Released March 3, 2008

ASTM VI Standard

Vapor Intrusion Condition (VIC) is defined as “the presence or likely presence of any volatile chemical of concern in existing or planned structures on a property resulting from an existing release or a past release from contaminated soil or groundwater on the property or within close proximity to the property, at a concentration that presents or may present a human health risk.”

OH 9-07 18

Liability Concerns

• Phase I Environmental Consultant

• Prospective/Current/Past Property Owner

• Property Lender

• Property Insurer

Regulatory Approach for HC SitesRegulatory Approach for HC Sites

• Current Regulatory Approaches:Current Regulatory Approaches:– USEPA: Guidance not recommended for UST sitesUSEPA: Guidance not recommended for UST sites– ASTM: Screening distance reduced from 100’ to 30’ASTM: Screening distance reduced from 100’ to 30’– Some agencies include a 10X biodegradation factor Some agencies include a 10X biodegradation factor – ITRC: Use vertical profile to demonstrateITRC: Use vertical profile to demonstrate

• Data suggests these approaches are overly Data suggests these approaches are overly conservative for most petroleum release sitesconservative for most petroleum release sites

Methods to Assess VIMethods to Assess VI

• Indoor Air Sampling

• Groundwater Sampling

• Soil Phase Sampling

• Predictive Modeling

• Measure Flux Directly

• Soil Gas Sampling

• Supplemental Tools/Data

Ingredients for Effective Ingredients for Effective VI AssessmentsVI Assessments

• Investigatory Approach

• Determine Correct Screening Levels

• Sample & Analyze Properly

• Know & Use Supplemental Tools

• Demonstrating Bioattenuation

Some Key VI Assessment IssuesSome Key VI Assessment Issues

• Experience of the Collector/Consultant– Have they done this before?– Do they understand RBSLs? – Quality/experience of field staff? Sr or Jr?

• Get Enough Data Near/Around/Under

• Legal Perspective– How conservative to be or not be?

Most Common VI BloopersMost Common VI BloopersUnit Confusion:•Assuming ug/L equivalent to ppbv•Assuming ug/m3 equivalent to ppbv•Vacuum units: in Hg to inches H20

Screening Levels:•Comparing to CHHSLs•Not calculating correct levels

Approach GeneralizationsApproach Generalizations

• Indoor Air– Always find something – Multiple sampling rounds: extra time & $

• Groundwater Data– Typically over-predicts risk

• Soil Phase Data– Typically not allowed; over-predicts risk

• Soil Gas Data– Transfer rate unknown– Sub-slab intrusive

Indoor Air MeasurementIndoor Air Measurement• Pros:

– Actual Indoor Concentration

• Cons:– Where From?

– Inside sources (smoke, cleaners)– Outside sources (exhaust, cleaners)– People activities – NO CONTROL!

– Time-intensive protocols– Snapshot, limited data points – Expensive!!

                                                                                                                                                                                                       

Ambient Air Benzene at 23 CA Sites

ARAMCO Art and Crafts Goop

Aleenes Patio & Garden Adhesive

Consumer Products Containing PCE

Product

Gumout Brake Cleaner

PCE Concentration

Hagerty Silversmith Spray Polish

Champion Spot it Gone

Plumbers Goop Adhesive

Liquid Wrench Lubricant w/ Teflon

Not Specified

70%

50 - 90%

67.5%

30.5%

20 - 25%

65 - 80%

KEY POINT:

Wide variety of consumer products still contain high concentrations of PCE.

Indoor AirIndoor Air

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

2004 2005 2006 2007 2008

Indoor concentration of 1,2-DCA increasing over time. New indoor source = molded plastic (e.g., toys, Christmas decorations).

New Indoor Source of 1,2-DCANew Indoor Source of 1,2-DCA

KEY POINT:

CONCENTRATIONDETECTION FREQUENCY

1,2-

DC

A D

etec

tio

n

Fre

qu

ency

(%

)

1,2-

DC

A C

on

cen

trat

ion

(u

g/m

3 )

USEPA INDOOR AIR LIMIT

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2004 2005 2006 2007 2008

<0.08 <0.08 <0.08

Median 1,2-DCA Conc.

90%ile 1,2-DCA Conc.

OH 9-07 30

Passive Soil Gas Samplers

Adsorbent inside tube open on one

end

Adsorbent inside badge

Adsorbent inside vapor permeable, waterproof

membrane

Approach GeneralizationsApproach Generalizations

• Indoor Air– Always find something – Multiple sampling rounds: extra time & $

• Groundwater Data– Typically over-predicts risk

• Soil Phase Data– Typically not allowed; over-predicts risk

• Soil Gas Data– Transfer rate unknown– Sub-slab intrusive

ModelingModeling

• Johnson-Ettinger Most Common– GW, soil, soil gas spreadsheets– Screen & advanced versions– EPA-OSWER: no longer an exit

• Biovapor– Includes bioattenuation– Agency acceptance?

What is BioVapor? What is BioVapor?

Free, easy-to-use vapor intrusion model that accounts for oxygen-limited aerobic vapor intrusion.

Free, easy-to-use vapor intrusion model that accounts for oxygen-limited aerobic vapor intrusion.

KEY POINT:

1-D Analytical Model

1-D Analytical Model

Oxygen Mass Balance

Oxygen Mass Balance

Version of Johnson & Ettinger vapor intrusion model modified to include aerobic biodegradation (DeVaull, 2007).

Uses iterative calculation method to account for limited availability of oxygen in vadose zone.

Simple interface intended to facilitate use by wide range of environmental professionals.

User-FriendlyUser-Friendly

O2 HC

SIMPLE MATHSIMPLE MATH

Conceptual ModelConceptual Model

3 Advection, diffusion, and dilution through building foundation

2 Diffusion & 1st order biodegradation in aerobic zone

1 Diffusion only in anaerobic zone

Vapor Source

HydrocarbonHydrocarbon

OxygenOxygen aerobic zoneaerobic zone

anaerobic zoneanaerobic zone

Algebra Solution for:

Oxygen demand = Oxygen Supply

BioVapor – API 1-D Steady State VI Model

Which Soil Gas Method?Which Soil Gas Method?

• Active?

• Passive? (limited use)

• Flux Chambers? (limited use)

Active method most often employed for VI

Probe ConsiderationsProbe Considerations• Tubing Type

– Rigid wall tubing ok (nylon, teflon, SS)– Flexible tubing not (tygon, hardware store)– Small diameter best (1/8” or ¼”)

• Probe Tip – Beware metal tips (may have cutting oils)

• Equilibration Time– Effects by air knife, rotary, air percussion, sonic

• Equipment Blanks– Need to collect blank through collection system

Soil Gas Sampling IssuesSoil Gas Sampling Issues

• Sample Size – Greater the volume, greater the uncertainty– Smaller volumes faster & easier to collect

• Containers– Canisters: More blank potential. Higher cost – Tedlars: Good for ~2 days. Easier to collect

• Flow Rate– Really not imp. But most agencies < 200 ml/min

• Tracer/Leak Compound– Crucial for sub-slab & larger sample volumes – Gases (He, SF6, Propane) & Liquids (IPA)

Beware of the HardwareBeware of the Hardware

Poor HardwarePoor Hardware

Container IssuesContainer Issues

Large vs. mini-canisters

Filling a tedlar bag with syringe

Common Soil Gas AnalysesCommon Soil Gas Analyses • VOCs

– Soil & Water Methods: 8021, 8260– Air Methods: TO-14, TO-15, TO-17

• Hydrocarbons– 8015 m, TO-3

• Oxygen, Carbon Dioxide– ASTM 1945-96

• SVOCs (sorbent methods)– Air Methods: TO-4, TO-10, TO-13

On-site TO-15 Scan/SIMOn-site TO-15 Scan/SIM

• Simultaneous Scan/SIM mode enables

< 10 ug/m3 for All VOCs &

~ 1 ug/m3 for subset of compounds.

• Only 2cc of Sample. Eliminates Hardware

• Real-time Analysis in Structures: Control!

• Two “Mobile Air Labs” Now Operational

• Can Go Into Automated Mode

Don’t Forget 8021Don’t Forget 8021

• Can get to 1 ug/m3 for TCE, CCl4, PCE

• Can get to ~25 ug/m3 for Benz & Napthalene

• 5 minute run time for benzene, TCE & PCE

• Cost ~ 1/5 of TO-15

Supplemental Tools/DataSupplemental Tools/Data

• Site Specific Alpha Using Radon– Factor of 10 to 100. $100/sample

• Indoor Air Ventilation Rate– Factor of 2 to 10. <$1,000 per determination.

• Soil Physical Properties – Moisture content the key parameter

• Real-Time, Continuous Analyzers – Can sort out noise/scatter

Soil Gas Sampling for HCsSoil Gas Sampling for HCs

• Might Need to Sample <5’ bgs– If samples >5’ bgs exceed allowable levels– How to know? On-site analysis best– If not, collect samples anyway

• Always Collect Oxygen Data

• Might Need Soil Phase Data

Sub-Slab vs. Near-Slab SamplesSub-Slab vs. Near-Slab Samples

?

Dirty Groundwater Dirty Groundwater (>100 ug/l) at Site(>100 ug/l) at Site

Dirty Soil (>1 ppm) at SiteDirty Soil (>1 ppm) at Site

Subslab Data Subslab Data (ug/m3 benzene)(ug/m3 benzene)

Service station

8.3

4.34.6

NDND

1110

7.26.9

6.510

12

5.33.1

5.9

12.

4.9

2013/7.7

10

8.3

12

8.3

8.4

8.3

NDND

ND

ND

9.2

9.8

16/24

5.4

6.7

GW0 100 ft

The CulpritThe Culprit

BBQ Sample ResultsBBQ Sample ResultsAnalyte BBQ Garage Patio Garage #2 Closet

methane 40% 90% 100% nd (0.1%) nd (0.1%)

ug/m3 ug/m3 ug/m3 ug/m3 ug/m3n-hexane 1700 2000 10000 nd (15) nd (15)cy-hexane 750 5500 12000 nd (20) 21n-heptane 460 710 3100 nd (50) nd (50)benzene 270 340 1900 6.5 7.9toluene 150 110 120 44 62xylenes 40 105 177 113 33tri-methyl benzene 3 85 25 110 nd (10)tri-methyl pentane nd (200) 300 nd (200) nd (20) nd (20)

Previews of the VI FuturePreviews of the VI Future

• VI Likely to be a Concern at Your Sites

• Variable Regulatory Guidance Makes Assessment Tricky & Slow

• New EPA & DTSC Guidance to be Stricter

• ESLs to Go Lower?

• Hydrocarbons to be Less of a Concern

Want to Know More?Want to Know More?

• ITRC 2-day VI Training – 2010– July 12: Boston– October 4: Atlanta

• AWMA 2-day – Chicago 9/29/2010

• Tanks Conf, PVI Workshop, Boston 9/2010

• AEHS –MA: PVI Workshop – Oct 2010

Existing Documents & TrainingExisting Documents & Training

• Soil Gas Sampling SOPs– Soil Gas Sampling, Sub-slab Sampling, Vapor

Monitoring Wells/Implants, Flux Chambers (www.handpmg.com)

• Other – ITRC VI Guidance (www.itrcweb.org)– API Soil Gas Document (api.org)– ASTM E2600-08: Good Summary Table in App X

VI DocumentsVI Documents

• Overview of SV Methods (www.handpmg.com)– LustLine Part 1 - Active Soil Gas Method, 2002– LustLine Part 2 - Flux Chamber Method, 2003– LustLine Part 3 - FAQs October, 2004– LustLine Part 4 – Soil Gas Updates, Sept 2006– LustLine – VI For Petroleum Hydrocarbons, May 2010

• Robin Davis’ Articles on Bioattenuation:– Lustline #61 May 2009 – LustLine #52 May 2006 (www.neiwpcc.org)

Blayne HartmanHartman Environmental Geoscience

H&P Mobile Geochemistry858-925-7206

www.handpmg.com