vapor intrusion risk pathway regulatory updates & practical field lessons

Vapor Intrusion Risk Pathway:

Regulatory Updates &

Practical Field Lessons

BlayneHartman Ph.D.

858-204-6170

blayne@hartmaneg.com

February 2012

CA-CUPA

EPA Guidance Updates (Release Date: 6/2014)

• EPA (OSWER & Superfund) - Anticipated

– Preference for sub-slab & indoor air

– 7 to 30 day indoor air sampling period

– Fixed Att factor of 0.03 for SG & 0.001 for GW

– Sub-slab Att factor 0.03

– Modeling no longer an exit

http://www.epa.gov/oswer/vaporintrusion

No Public Comment on Draft!!

EPA Guidance Updates (Release Date: 6/2014)

• EPA-OUST: Guidance for HCs

– Exclusion criteria? Yes

– Testing/Adoption of Biovapor model? In theory

– Frequently Asked Questions - done

– Summary of State Guidances - done

http://www.epa.gov/oust/cat/pvi/index.htm

No Public Comment on Draft!!

New TCE Standard

(As of October 2011)

• Residential (1e-6)

– Indoor Air cancer: 0.43 ug/m3 (down from 1.2 ug/m3)

– Indoor Air non-cancer: 2.1 ug/m3

– Groundwater: 1.1 ug/L

• Commercial/Industrial (1e-6)

– Indoor Air: 3.0 ug/m3 (down from 6.1 ug/m3)

– Indoor Air non-cancer: 8.8 ug/m3

– Groundwater: 7.4 ug/L

EPA R9 & DTSC Have Adopted

OEHHA Has Not Adopted C/I

New PCE Standard

(As of March 2012)

• Residential (1e-6)

– Indoor Air cancer: 9.4 ug/m3 (up from 0.41 ~22x !!)

– Indoor Air non-cancer: ~47 ug/m3

• Industrial (1e-6)

– Indoor Air: ~47 ug/m3 (up 22x)

– Indoor Air non-cancer: 8.8 ug/m3

EPA R9 Has Adopted

DTSC & OEHHA Have Not Adopted Either!

ITRC PVI GUIDANCE (Due out early 2014)

1. Introduction

2. Types of PVI Sites

3. Conceptual Site Model

4. Basic Investigative Framework for PVI Sites

5. Site Screening and Prioritization

6. Investigative Toolbox

CA Agencies

• CA-DTSC

– New VI Guidance (10/2011) & Soil Gas Advisory (4/2012)

– Recently adopted RAGS Part F

• EPA Region 9

– Adopted Region 3 Screening Levels for TCE & PCE

• SF-RWQCB

– ESLs updated January 2013

• OEHHA

– Still using out-dated CHHSLs (pre RAGS Part F)

• SWQCB

– Low Threat Closure Policy – Summer 2012

DTSC VI Guidance Changes

• Preference for Sub-slab Samples for Cl-VOCs

• Collect Exterior SG Samples At Source

• Repeated Sampling of Soil Gas

• Raising Sub-slab AF to 0.05 (5x stricter)

• Can now measure permeability, diffusivity and radon for attenuation factor

• Changes in Toxicity of Some Compounds

Defers to LUFT Manual for Petroleum HCs (p.38)

Soil Gas Allowed Levels

PCE in Soil Gas, Residential Receptor

RBSL (ug/m3)

DTSC Sub-slab 8.2

EPA Sub-slab (new) 300

CHHSL 180

DTSC – 5’ soil gas 205

EPA R9 – 5’ soil gas now 4,700

EPA R9 – 5’ soil gas new 300

DTSC Soil Gas Advisory Changes

• Sampling

– Purge volumes: include dry bentonite

– Equilibration times: 2 hours for tubes, ? for probes

– Leak check specifications: report at VOC RL

• Analysis

– Methods 8021, 8260, TO-14, TO-15, TO-17 ok

– Naphthalene preferred by TO-17

– Syringes & tedlar bags ok to use (in lieu of canisters)

Low Threat Closure Policy VI Scenarios

LNAPL: 30’ Dissolved: 5’ or 10’

Dissolved with O2 12

Low-Threat Closure Policy

• If 30’ of Biozone, NAPL screens out

– Vertically & horizontally

• If 10’ of Biozone, benzene up to 1000 ug/L

• If 5’ of Biozone, benzene up to 100 ug/L

Bioattenuation zone: TPH-soil < 100 mg/kg

Site Screens Out from VI Pathway if:

Note: O2 not Required

Low-Threat Closure Policy

The Power of Oxygen

• Separation distance drops from 10’ to 5’ for

benzene up to 1000 ug/L

• Soil gas SLs increase by 1000x!

TPH-soil required for all scenarios but O2 not

If oxygen in soil gas >4%:

Allowable Benzene in GW 1e-6 risk, Residential Scenario

• DTSC VI Guidance:

0.084 ug/m3 / 0.002 = 0.42 ug/L / 0.2 = 0.21 ug/L

• New EPA OSWER Guidance:

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

~3000 times lower than EPA-OUST Value!!

~5000x lower than Low Threat Value of 1000 ug/L ____________________________________________________

Soil Gas Allowed Levels

Benzene in Soil Gas, Residential Receptor, 1-6 Risk

RBSL (ug/m3)

DTSC Sub-slab 1.6

CHHSL 37

DTSC – Step 5 42

CA Low-Risk Policy: O2<4% 85

CA Low-Risk Policy: O2>4% 85,000

Ambient levels: 1 to 10 ug/m3

Low-Threat Policy:

A VI Pathway Game Changer

• Active Service Stations Excluded

• Sampling

– Soil phase TPH needed from two depths

– O2 in soil gas

• Soil Gas Analysis

– Needed at all?

– Benzene, ethylbenzene & naphthalene only

– No longer worry about TPH??

VI Assessments Much Simpler & Less Expensive

Methods 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

VI Assessments

• Investigatory Approach

• Determine Correct Screening Levels

• Sample & Analyze Properly

• Know & Use Supplemental Tools

• Demonstrating Bioattenuation

The Most Important Ingredient

• Experience:

– Consultant

– Collector – done soil gas before?

– Lab – certified for methods?

– Regulator

– Public

– YOU!

What level person is going in the field?

Most Common VI Bloopers

• Unit Confusion

– Assuming ug/L equivalent to ppbv

– Assuming ug/m3 equivalent to ppbv

• Screening Levels

– Comparing to generic screening levels

– Not calculating correct levels

• Sampling & Analysis Errors

– Program design: soil gas? GW? SS? IA?

– Using wrong hardware

– Using wrong analysis

O2=7.5%

Probe Considerations

• Tubing Type – Rigid wall tubing ok (nylon, teflon, SS)

– Flexible tubing not (tygon, hardware store)

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

• Materials Used to Bury Probes – Sand, cement

• Equipment Blanks – Need to collect blank through collection system

Some Lessons Learned

•Do not mark sample locations with spray paint: toluene

•Watch what you use to seal holes

Loaded with TCE

Loaded with TBA

Deconning or Contaminating?

Better Be Sure to Triple Wash!

Benzene =1530 ug/m3

Soil 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 & Purge Volume – 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)

Leak Testing

Gases

Tent Shroud

Liquids

Vacuum Test

Canisters vs Tubes

SVOC Sampling

Typical

Simpler

Beware of the Hardware

TO-17 for Soil Gas Samples

Advantages:

• Fast & Easy to Sample. No pumps, swageloks, chokes

• Disposable - No Chance of Carry-over/False Positives

• Easy/cheaper to Handle & Ship

• 2 Tubes per Sample Ensures Meeting RSLs

Why use one of these?

On-site TO-14 (8021)

• Small Footprint GC (Flies free on SW)

• Fast Start-up (~45 min)

• 5 minute run time for TCE & PCE

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

• But Also Can Measure High (>10,000 ug/m3)

• Cost ~ 1/4 of TO-15 ($50/sample)

• Can Go Into Automated Monitoring Mode

On-site GC: TO-14 Modified (ECD)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

7/26/2011 9/14/2011 11/3/2011 12/23/2011 2/11/2012 4/1/2012

Vap

or

Co

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ntr

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n (

ug/

m3

)

Date & Time

PCE Field GC Indoor Air Data - 422

1st 422 Basement 422

0

10

20

30

40

50

60

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90

100

110

120

130

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150

11/28/11 0:00 12/8/11 0:00 12/18/11 0:00 12/28/11 0:00 1/7/12 0:00 1/17/12 0:00 1/27/12 0:00 2/6/12 0:00

Vap

or

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ntr

atio

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ug/

m3

)

Date & Time

PCE Field GC Subsurface Air Data

SSP-2 WP-3 SGP9-6 SGP8-9 SGP2-9 SSP-4 A on A off B on

B/C off D on D off E on E off F on F off G on G off

0

50

100

150

200

250

300

11/23/2011 12/3/2011 12/13/2011 12/23/2011 1/2/2012 1/12/2012 1/22/2012 2/1/2012 2/11/2012 2/21/2012

Vap

or

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ntr

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ug/

m3

)

Date & Time

PCE & CHCl3 - SGP9-6

PCE CHCl3

Probe A3 (TCE - Normalized)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

13:5

0:09

10:5

0:26

7:50

:44

4:51

:04

1:51

:43

22:5

3:46

5:43

:29

2:43

:47

23:4

4:04

20:4

4:22

17:4

4:39

14:4

4:57

11:4

5:15

8:45

:32

16:0

2:01

13:0

2:18

10:0

2:36

7:02

:55

4:03

:12

1:43

:56

22:4

4:15

7:06

:41

4:06

:59

1:07

:19

22:0

7:58

19:1

1:25

Time (3/16/07 to 4/10/07)

Nor

mal

ized

Con

cent

ratio

n

Probe A3-3' (Port 9)

Probe A3-8' (Port 10)

Probe A3-17' (Port 5)

Soil Gas Temporal Study

Previews of the VI Future

• VI Likely to be a Concern at Your Sites

• Variable Regulatory Guidance Makes

Assessment Tricky & Slow

• New EPA OSWER Guidance to be Stricter

• ASTM Standard Increase # of Sites

• Hydrocarbons to be Less of a Concern

Forthcoming VI Events

• AEHS Conf – San Diego: March 18, 2013

– CALUFT & Low Threat Policy Workshop (Mon)

– EPA OSWER & OUST all Day Workshop (Tues)

– Petroleum VI Workshop (Tues night)

– All Day Session/Presentations on VI

Blayne Hartman, Ph.D.

858-204-6170

blayne@hartmaneg.com

www.handpmg.com