Myths and Misconceptions about Screening for Vapor Migration in Phase Is
Misconceptions with Vapor MigrationScreening using ASTM E 2600-10 in a Phase I by Anthony J. Buonicore, P.E., DEE, QEP CEO, The Buonicore Group Chairman, ASTM Vapor Intrusion Task Group for presentation at EDR Due Diligence at Dawn Seminar Spring 2012
Overview Top 10 Misconceptions about E 2600-10 Suggested Steps for Conducting a Tier 1 VEC Screen as part of a Phase I Considerations in Making a VEC-REC Determination
Misconception #1“Vapor migration screening is notpart of a Phase I unless the clientasks for it or the state where theproperty is located has vaporintrusion regulations. Moreover,E 2600-08 says it is optional.”
WRONG! E 2600-08 has been superceded by E 2600-10 CERCLA definition of release of hazardous substances includes “emitting” and “escaping” into the environment (which includes “into subsurface strata.” AAI Rule says EP must provide “an opinion as to whether the inquiry has identified conditions indicative of releases or threatened releases of hazardous substances…on, at, in or to the property.”
WRONG! ASTM E 1527 definition of a REC includes “presence or likely presence of any hazardous substances or petroleum products…indicate an existing release, a past release or a material threat of a release…into structures…into the ground…” CERCLA, AAI and the REC definition do not differentiate “releases” by media, i.e., solid, liquid or vapor. E 1527 is currently being revised to clarify that vapor migration must be treated no differently than contaminated groundwater migration in a Phase I…
E 1527 Ballot Revisions Clarifying that Vapor Migration is tobe Treated No Differently than Contaminated Groundwater Migration CERCLA definitions of “release” and “environment” added E 2600-10 specifically referenced in Documents Section Definition of “migration” added: “movement of hazardous substances or petroleum products in any form, including solid and liquid at the surface or subsurface, and vapor in the subsurface” and specifically mentioned in a number of sections in the standard Regulatory agency files should be reviewed if the property or adjoining identified in records research if EP judges that it is warranted – would assist in evaluating potential impact of vapor migration from nearby sites that have been “remediated” without vapor pathway considered Non-scope considerations – Indoor Air Quality – clarified to say “unrelated to releases of hazardous substances or petroleum products
Misconception #2“ The REC definition includes releases or threatened releases “into structures” on the property. This mean that vapor intrusion into structures needs to be evaluated in an ASTM E 1527 Phase I.”
WRONG! Vapor intrusion assessment involves an indoor air quality evaluation. E 1527 specifically identifies indoor air quality as a “non-scope consideration” in a Phase I. If a VEC exists or is likely or cannot be ruled out, and the EP determines that it represents a REC in the Phase I, a follow-on investigation can be conducted to evaluate the potential for vapor intrusion. If it is determined that a VEC can be ruled out because it does not exist or is unlikely to exist, then the issue of whether vapors may intrude into structures on the property is moot.
Misconception #3“ If a VEC exists or is likely to exist, there is no way to close a deal without an extensive site investigation that will probably kill the deal.”
WRONG! If a VEC exists or is likely to exist or cannot be ruled out, the deal can still be closed by doing “pre-emptive mitigation.” Since vapor intrusion mitigation measures can be estimated reasonably accurately (generally in the $2 – $7/SF range, depending on mitigation measure), this cost can be used to adjust the deal price similar to the way that the presence of asbestos has been used to adjust the deal price (since asbestos removal costs can also be estimated reasonably accurately). The cost to pre-emptively mitigate can be much less than the cost to conduct a VI site investigation to determine if a
Misconception #4“Both Tier 1 and Tier 2screening in E 2600-10 must beconducted to evaluate vapormigration.”
WRONG! Tier 1 was designed as the methodology for vapor migration evaluation in a Phase I. If a VEC exists or is likely or cannot be ruled out based upon the Tier 1 evaluation, Tier 2 was designed as the suggested follow- up (effectively equivalent to a “vapor” Phase II).
Misconception #5“Using the distances specified inTier 1 to identify the area ofconcern results in too many sitesthat need evaluating. This cantake significant time.”
WRONG! The Tier 1 distances for the AOC are just the starting point. They conservative and represent 90th percentile plume lengths and widths! The EP can reduce the Tier 1 distances significantly using professional judgment, e.g., with respect to groundwater flow direction, soil characteristics, intercepting utility corridors, etc. When the AOC is minimized using professional judgment, there will be far fewer sites that need to be evaluated further.
WRONG! Only for HUD multifamily Phase Is! (Note: HUD projects involve residential properties where virtually all the vapor intrusion litigation can be found.) More often than not, VECs will not be RECs. More often than not, a known or suspect contaminated site (with potential vapor migration) located nearby and up-gradient from the TP would have been judged a REC anyway from a groundwater migration viewpoint (irrespective of the additional concern over vapor migration). More on this later!
Misconception #7“Vapor migration analysis needonly be performed on RECs sincea VEC would have been a RECanyway.”
WRONG! If vapor migration evaluations are only performed on RECs, then the implicit assumption is that only contaminated groundwater migration will be considered to determine if there is a REC. This will eliminate conditions that become RECs solely because of the potential for vapor migration. For example… If vapor migration is not being considered, a down-gradient nearby (but not adjacent) dry cleaner would not likely be considered a REC since the contaminated groundwater plume would be moving away from the TP. However, today it may be considered a REC solely based upon vapor migration potential (vapor migration does not have to follow groundwater direction, but rather the path of least resistance which can be opposite groundwater flow direction).
Misconception #8“There is no guidance on evaluatingVECs to determine if they areRECs.” - 7
WRONG! The best guidance is the REC definition itself and specifically the de minimis definition Two conditions for de minimis - not a threat to human health and the environment AND - would not be subject of an enforcement action if brought to the attention of appropriate government agencies De minimis conditions are not RECs More on this later!
Misconception #9“The future use of a property isnot taken into consideration inE 2600-10.”
WRONG! For Tier 1 screening, distances are measured from a known or suspect contaminated site to the target property boundary If vapors are likely to penetrate the property boundary, then a VEC is likely irrespective of the status of the property Future use comes into play more often than not with determining if the VEC is a REC
Misconception #10“E 2600-10 conflicts with state vaporintrusion guidance.”
WRONG! State guidance focuses on vapor intrusion assessment (and vapor migration from the source of contamination – could be from the edge of a contaminated soil or groundwater plume - to the building) E 2600-10 focuses on the potential for vapors to encroach upon the property, i.e., vapor migration from a known or suspect contaminated site to encroach upon the TP boundary E 2600-10 complements state guidance in that it effectively acts as a screening tool If a VEC exists or is likely or cannot be ruled out, state guidance can assist in determining if the VEC is a REC
The jury is still out on…“Dealing with nearby remediated/closed/NFA siteswhere vapor pathway was NOT taken intoconsideration.”Is it necessary to review the regulatory files?E 1527 Task Group has proposed for the 2013 revision torequire the EPs to review pertinent regulatory files on nearbyproperties that in their judgment have the potential to impactthe target property!
Suggested Steps for Conducting a Tier 1 VEC Screen(assuming no preferential pathways direct to the TP from contaminated sites)1. Identify AOC and minimize to the maximum extent possible based on experience ● Start out with 1/3rd mile or 1/10th mile (for petroleum hydrocarbons), BUT ● Can reduce significantly when GW flow direction known or can be inferred (from topographical data or nearby Phase II data or hydrologic data, etc.) ● Can further reduce by using professional judgment based on local knowledge ● Hydraulic barriers (such as rivers and wetlands) ● Sub-surface man-made physical barriers (preventing vapors from reaching TP such as utility lines in a main road that can intercept migrating vapors moving toward a TP) ● Sub-surface natural barriers (preventing vapors from reaching the TP such as confining layers, e.g., low permeability soil (e.g., clay layer) or fresh water lens
Net Reduction in AOC for Tier 1 Screening of Known or Suspect COC SOURCES E 2600-10 w/ Source Location E 2600-10 Buonicore Methodology* Up-gradient 1,760’ 1,760’ Down-gradient 1,760’ 100’ Cross-gradient 1,760’ 365’ * Buonicore, A.J. , Methodology for Identifying the Area of Concern Around a Property Potentially Impacted by Vapor Migration from Nearby Contaminated Sources, Paper No. 2011-A-301, Proceedings, Air & Waste Management Association, 104th Annual Sources, Proceedings, Meeting, Orlando, Florida, June 20-24, 2011.
Net Reduction in AOC for Tier 1 Screening of Known or Suspect PHC SOURCES E 2600 Revised w/Source Location E 2600-08 Buonicore Methodology*Up-gradient 528’ 528’Down-gradient 528’ 100’ (LNAPL) 30’ (dissolved)Cross-gradient 528’ 165’ (LNAPL) 95’ (dissolved)* Buonicore, A.J. , Methodology for Identifying the Area of Concern Around a Property Potentially Impacted by Vapor Migration from Nearby Contaminated Sources, Paper No. 2011-A-301, Proceedings, Air & Waste Management Association, 104th Annual Sources, Proceedings, Meeting, Orlando, Florida, June 20-24, 2011.
Conducting a Tier 1 VEC Screen cont’d2. Are there any known or suspect COC- contaminated sites in the EP-defined AOC? ● Government records ● Historical research ● Other (?)3. Evaluate each site remaining in the EP-defined AOC ● Remediation status? ● Did remediation consider vapor pathway? ● Review AULs – contamination left on-site? ● Other (?)
Conducting a Tier 1 VEC Screen cont’d4. Identify VEC status ● exists (physical evidence) ● likely (within close proximity, e.g., two properties?) ● can not be ruled out (further away, beyond two properties?) ● can be ruled out because it does not or is unlikely to exist5. If VEC can be ruled out, vapor migration evaluation is completed
Conducting a Tier 1 VEC Screen cont’d6. If VEC exists/likely/cannot be ruled out, determine if VEC is a REC ● “De minimis” (?) ● Apply state VI guidance criteria (?) ● Other (?)7. If VEC is a REC, E 2600-10 Tier 2 provides a suggested vapor migration scope-of-work for follow- on investigation in Phase II (may also be part of a Phase II investigation into potential groundwater contamination)
Considerations in Making a VEC-REC Determination
Considerations What is the depth to contaminated groundwater? For example, VEC may exist or be likely because of groundwater contamination on or near the TP, but a REC (due to vapor migration) may not exist (under the de minimis condition clause) because the depth to groundwater may be greater than the applicable ASTM critical distance or distance identified in state VI guidance. [Of course, the presence of contaminated groundwater in and of itself may result in a REC anyway.]
Considerations cont’d Where is the nearest structure on the TP with respect to the contaminant plume? For example, VEC may exist or be likely because of groundwater contamination on or near the TP, but a REC (due to vapor migration) may not exist (under the de minimis condition clause) because the distance between the structure and the edge of the contaminated plume may be greater than the distance specified in state VI guidance. [Of course, the presence of contaminated groundwater in and of itself may result in a REC anyway.]
For example…● NJDEP VI Guidance: distance horizontally or vertically between the nearest edge of the contaminated groundwater plume and the nearest structure on the TP, equal to ●100’ for COC or LNAPL PHC-COC ● 30’ for Dissolved PHC-COC
For example…● State of Colorado is concerned when: ● Building “directly over or immediately adjacent to a subsurface source of contamination” ● Building “within one or two properties of the plume boundary or approximately 100 ft.”● Colorado Indoor Air Guidance, September 2004: distance horizontally or vertically between the nearest edge of the contaminated groundwater plume and the nearest structure on the TP, equal to ● 100’ for COC or LNAPL PHC-COC
Considerations cont’d What is the contaminant concentration? For example, a VEC may exist or be likely because of groundwater contamination on or near the TP, but a REC (due to vapor migration) may not exist (under the de minimis condition clause) because the volatile contaminant concentration is below the state risk screening level for groundwater. [Of course, the presence of contaminated groundwater in and of itself may result in a REC anyway.]
Considerations cont’d How has the structure on the TP been designed? For example, a VEC may exist or be likely because of groundwater contamination on or near the TP, but a REC (due to vapor migration) may not exist (under the de minimis condition clause) because the structure has been designed to be intrinsically safe from chemical vapor intrusion, i.e., no vapor pathway to potential human receptors. Examples might include a building designed to operate 100% of the time under positive pressure, or condos with open-air parking directly below the units, or buildings with radon mitigation systems. [Of course, the presence of contaminated groundwater in and of itself may result in a REC anyway.]
Where are there more likely to beRECs based solely on vapor migration considerations? Down-gradient known or suspect contaminated sites Cross-gradient known or suspect contaminated sites Vapor migration takes the path of least resistance no matter what direction it is!
Where is it more likely that what caused a VEC would have been viewed as a REC anyway even ifvapor migration was not considered? Up-gradient known or suspect contaminated sites
VEC-REC determination is impacted by: State VI Guidance and E 1527-05 de minimus criteria in REC definition Soil characteristics, subsurface confining layers and depth to water table Hydraulic barriers Physical barriers Building design and location on property Building operation
Bottom Line EP must consider vapor migration no differently than the way contaminated groundwater migration is considered in a Phase I EP can evaluate vapor migration using whatever methodology the EP determines to be appropriate (if not E 2600-10, then EP needs to document “alternative” methodology and include documentation in the Phase I) E 2600-10 Tier 1 screening methodology is an industry consensus methodology E 2600-10 allows for EPs professional judgment and is therefore able to “cover” virtually any “alternative” vapor migration methodology (making a strong case for using E 2600-10)
Bottom Line If E 2600-10 Tier 1 screening indicates a VEC, EP must then decide as part of Phase I if VEC constitutes a REC - RECs can only be identified through the ASTM E 1527-05 standard practice - RECs do not include de minimis conditions E 2600-10 Tier 2 provides a suggested follow-on investigation of a Tier 1 VEC