17. Vapor Intrusion Risk Pathway:
A Survival Guide
Blayne Hartman
Hartman Environmental Geoscience
858-204-6170
blayne@hartmaneg.com
August 2013
EDR Webinar
18. Potential Risk of VI Sites
yesno
no yes
Start
Petroleum Site?
Whew!
Gulp!
TCE Site?
Ouch
19. EPA Guidance Updates
(Release Date: 2014?)
• EPA (OSWER & Superfund)
– Preference for sub-slab & indoor air
– Preference for soil gas near source (bad for HCs!)
– Longer indoor air sampling period (7 to 21 days)
– Fixed Att factor of 0.03 for shallow SG (~15x drop)
– Sub-slab Att factor 0.03 (3.3x increase)
– Modeling no longer an exit
http://www.epa.gov/oswer/vaporintrusion
Comment Period Ended 6/24/13
20. EPA Guidance Updates
(Release Date: 2014?)
• EPA-OUST: Guidance for HCs
– Exclusion criteria? Yay!
– Testing/Adoption of Biovapor model? Wishy-washy
– No Screening Levels – Pipes you to OSWER!!
http://www.epa.gov/oust/cat/pvi/index.htm
Comment Period Ended 6/24/13
21.
22. Allowable Benzene in GW
1e-6 risk
• New OSWER Guidance:
0.31 ug/m3/0.001 = 0.31 ug/L/0.2 = 1.5 ug/L
• EPA-OUST Exclusion Value: 5000 ug/L
OSWER ~3300 times lower than OUST!!
23. 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
7. Mitigation
24. New TCE Standard
(As of October 2011)
• Residential (1e-6 cancer risk)
– Indoor Air cancer: 0.43 ug/m3 (down from 1.2 ug/m3)
– Indoor Air non-cancer: 2.1 ug/m3 Short-Term Exposure?
– Groundwater: 1.1 ug/L
• Commercial/Industrial (1e-6 cancer risk)
– Indoor Air: 3.0 ug/m3 (down from 6.1 ug/m3)
– Indoor Air non-cancer: 8.8 ug/m3 (Pregnant employees?)
– Groundwater: 7.4 ug/L
25. 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: 175 ug/m3
CA-EPA Ignored new PCE Standard
26. Methods to Assess VI
• Indoor Air Sampling
• Groundwater Sampling
• Soil Phase Sampling
• Predictive Modeling
• Measure Flux Directly
• Soil Gas Sampling
• Supplemental Tools/Data
27. Ingredients for Effective
VI Assessments
• Investigatory Approach
• Determine Correct Screening Levels
• Sample & Analyze Properly
• Know & Use Supplemental Tools
• Demonstrating Bioattenuation
28. 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?
30. 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
32. Approach Generalizations
• Indoor Air
– Always find something
– Multiple sampling rounds:
• Groundwater Data
– Typically over-predicts risk
• Soil Phase Data
– Typically not allowed; over-predicts risk for HCs
• Soil Gas Data
– Transfer rate unknown
– Sub-slab intrusive
33. Indoor 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!!
42. Which Soil Gas Method?
• Active?
• Passive? (limited use)
• Flux Chambers? (limited use)
Active method most often employed for VI
43. 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
44. 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)
47. Supplemental 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.
• Continuous analyzers
– Real-time monitoing
• Pressure Measurements
– Can help interpret indoor air results
Refer to ASTM E2600-08 Table X.1 for summary table
48. 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
50. 0
0.5
1
1.5
2
2.5
3
3.5
4
0 50 100 150 200 250 300 350 400 450 500 550 600
Conc(ug/m3)
Run Number
PCE - 420 1st Floor Air
PCE
Continuous Monitoring – PCE in Indoor Air
12/2012 3/20131/2013 2/2013
3 days 5x
3 days 10x
2 days 4x
51. Continuous Monitoring – PCE in Indoor Air
12/2012 3/20131/2013 2/2013
0.28
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
0 50 100 150 200 250 300 350 400 450 500 550 600 650
422 1st Floor Air
PCE
4 days 10x
3 days 5x
1 day 5x 2 days 10
52. 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
53. VI 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, Nov 2010
• Robin Davis’ Articles on Bioattenuation:
– Lustline #61 May 2009
– LustLine #52 May 2006 (www.neiwpcc.org)
54. Existing 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
55. VI Websites & Links
• www.handpmg.com
– Soil Gas Information
– Other Site Assessment Methods
• www.itrcweb.org
• www.api.org
58. Case Study #1
• Bloomington 1 (Sub-Slab Depressurization (SSDS))
– 6,500 SqFt. footprint with two stories
– Former dry cleaner across alleyway to the west of
building
– Building constructed into side of a hill on west side
– Mitigated at night to avoid conflict with sensitive
tenants
– 5 sub-systems connected to 6 extraction points
– Roof mounted fans to preserve historic district
building appearance
62. Case Study #2
• Bloomington 2 (Modified Ventilation)
– 2,800 SqFt. footprint with three stories (inc.
basement) Top floor of building is residential
– Active dry cleaner adjacent and building
historically stored dry cleaning chemicals &
filters
– Client conducted 1st pilot study
– High water table and bedrock within 2 feet of
basement floor
– SSDS not applicable
63. HRV/ERV
HRV/ERV - Heat
Recovery Ventilators
/ Energy Recovery
Ventilators
• Typical Application
– very low
concentrations of COC
in indoor air
65. Pilot Study – HRV/ERV &
Building Pressurization
• Blower Door Test
– Must find air exchanges per hour (ACH)
– HRV/ERV is limited by the amount
of reduction in COC concentration
needed
68. Case Study #3
• Indianapolis Residential (SSDS and Sub-
Membrane Depressurization (SMDS))
– EPA Superfund site with upwards of 125
impacted residences
– Former dry cleaner upgradient from
neighborhood
– First selected mitigation contractor was a radon
specialist – Lowest bidder
– Most (75%) of the houses mitigated by first
contractor were not up to code or properly
mitigated
71. Key Lessons Learned
• Many different approaches to deal with a
vapor intrusion issue
• Each building is different
– Assumptions are extremely dangerous
– Site specific data is crucial to getting the best
designed system
• Partnering with experience matters
72. Keep Vapor from Killing Deals
Proper Mitigation + Monitoring = Corrected
Vapor Intrusion Issue
• Quickly installing a proper mitigation
solution keeps environmental remediation
projects moving toward closure
• Once a mitigation system is installed
ensuring that it is working properly at all
times is crucial
73. System Installed… Now what?
• Once a mitigation system has been
installed on a structure:
– How do I prove to all stakeholders that the
system is still functioning adequately after the
confirmatory sampling event?
– How often should I continue to verify the
system is preventing exposure?
74. EPA Draft OSWER Guidance
• Multiple mentions of follow up
monitoring of installed mitigation
systems.
• Opportunity to avoid re-sampling events
if you can show site conditions warrant a
different monitoring schedule.
• Monitoring is a key part of Long Term
Stewardship concept.
75. Key OSWER Concepts
• Routine inspection of all visible
components of the VI mitigation system
including fans, piping, seals, membranes,
and collection points to ensure there are
no signs of degradation or blockage.
• Routine monitoring of vent risers for flow
rates and pressures generated by the fan
to confirm the system is working and
moisture is draining correctly.
76. Key OSWER Concepts
• Confirmation that the extraction fan is
operating.
• Confirmation of adequate operation of the
warning device indicator.
• For SSDS, EPA recommends that the
pressure gauge be monitored quarterly to
verify the system is operating efficiently.
77. Key OSWER Concepts
• EPA recommends that the system failure
warning devices or alarms be installed on
active depressurization systems, and
appropriate responses to them should be
understood by building occupants.
Monitoring devices and alarms should be
placed in a readily visible, frequently
trafficked locations within the structure.
78. Comparison of Traditional vs.
Alternative Monitoring
• Traditional system monitoring relies on site
visits and informed building occupants to report
to the responsible party if an issue has caused
the system to stop functioning adequately
between scheduled monitoring events.
• Alternative monitoring allows the system to be
monitored remotely and removes the
responsibility of the building occupant to inform
the responsible party when a system issue arises.
79. Comparison of Traditional vs.
Alternative Monitoring
Traditional Alternative
Pressure gauge readings Onsite visit Real time data remotely
Confirmation fan is operating Onsite visit Real time data remotely
System Shut down Onsite visit Shut down remotely
Confirmation alarm is functioning Onsite visit Real time data remotely
Ongoing sampling events Onsite visit Reduced frequency
Telemetry technology can reduce the disturbance to building
occupants with less site visits by the environmental professionals for
monitoring and sampling events, while providing superior evidence
of system functionality.
EPA-OUST guidance proposed exclusion criteria for UST sites.
ITRC has convened a new technical workgroup to write guidance specifically for petroleum hydrocarbon sites.
7.5% oxygen in a working office space?? The lab says the analysis was confirmed as correct. How can this be?
Sub-slab soil gas data collected at another sub-slab location by a continuous analyzer shows little variation in values over 3 months from December 2012 to March 2013. The red bands show a bout 1-day of time. Observed variations are small and occur over long time frames weeks to months, not over short time frames (days). This means that grab samples are suitable for sub-slab samples. There is no advantage to 8-hr or 24-hr time period samples.