Blogs > Anthony Buonicore's - Tony's Vapor Intrusion Blog

Professional Judgment in VEC-REC Determinations (17 Comments)

Mon, 20 Dec 2010 15:59:12 +0000

As an instructor for the ASTM E 2600-10 VEC training course, I noticed some confusion over where professional judgment is applied. Should professional judgment be applied when conducting a Tier 1 screen in E 2600-10 so that there are the least number of properties contributing to a vapor encroachment condition and requiring further investigation? Or should professional judgment not be applied in E 2600-10 when deciding whether or not a contaminated property is creating a VEC, but rather be applied in the E 1527-05 Phase I when determining whether this VEC is a REC? My response is that professional judgment can be applied in either place. For example, assume the soil between the target property and a chlorinated solvent-contaminated property located 90 feet down-gradient from a target property is a relatively impermeable silty clay. Under the E 2600-10 Tier 1 screen, this contaminated property would represent a condition that could cause a VEC since the contaminated property is within 100 feet of the target property, and vapors, according to the critical distance definition in E 2600-10, could potentially reach the target property assuming the path of least resistance is in that direction. One approach is to identify the contaminated property in the example as creating a VEC under E 2600-10 since it is within 100 feet of the target property and then, when evaluating if this VEC is also creating a REC in the E 1527-05 Phase I, use the soil characteristics rationale to support your professional opinion that the VEC would not represent a REC. On the other hand, professional judgment can be applied just as well in the E 2600-10 Tier 1 screen to conclude that the down-gradient contaminated property in this example does not represent a VEC because of soil characteristics. In this latter case, the property then need not even be addressed as a potential REC in the Phase I.

The choice as to where professional judgment is better applied remains an open issue, or at least an issue to be dealt with on a case-by-case basis. With respect to my example, an advantage to applying it in the E 2600-10 Tier 1 screen is that it can eliminate a nearby contaminated property that potentially may create a VEC from any further consideration in the Phase I. An advantage to applying it in the Phase I (as part of the REC determination) is that it can simplify E 2600-10 Tier 1 screening.

It would be interesting to hear your rationales for where you would prefer to apply professional judgment with respect to VEC determination in Tier 1 screening under E 2600-10. Would your preference be to eliminate the contaminated property potentially creating a VEC in E 2600-10 Tier 1 screening, or would you prefer to keep it as a VEC and then use professional judgment to eliminate it from further consideration in the REC evaluation in E 1527-05?

MA DEP Issues New VI Guidance for Public Comment

Wed, 05 Jan 2011 23:06:19 +0000

Entry by abuonicore

On December 14, 2010, the Massachusetts DEP released its newly-revised vapor intrusion guidance document, seeking public review and comment by March 1, 2011. The new draft guidance is a continuation of MassDEP's pioneering efforts in this arena. In 1993, Massachusetts became the first state in the country to establish regulations and cleanup standards for the assessment and cleanup of sites where vapor intrusion was a pathway of concern. In April 2006, the DEP, because of vapor intrusion concerns, significantly lowered regulatory groundwater cleanup standards for chlorinated solvents associated with contaminated groundwater within 30 feet of a building and where the average depth to groundwater was 15 feet or less. In 2006, the DEP also undertook a PCE initiative that involved re-opening approximately 100 previously closed sites because of vapor intrusion concerns (with 68 of these sites requiring further action). In 2008 the DEP issued guidance identifying typical indoor air concentrations based on the detections of such contaminants in typical residential settings and the risks posed by these contaminants. The DEP also issued guidance describing how such values should be used in evaluating the vapor intrusion pathway.

The latest guidance document is very negative on modeling. The DEP maintains that modeling based on subsurface contaminant levels (in groundwater, soil or soil gas) is not predictive of indoor air concentrations and therefore should not be used for site screening. Since the DEP does not accept modeling as a predictive tool, there would be no way to address the potential for vapor intrusion in future construction. As such, the DEP in its guidance proposes an engineering approach to protect future buildings.

The guidance document, including the main text and appendices, can be accessed on the DEP's Indoor Air Guidance Project blog (http://indoorairproject.wordpress.com). It is well worth reading.

Relationship Between VECs and RECs (10 Comments)

Wed, 14 Jul 2010 21:57:43 +0000

Entry by abuonicore

Entry

Is a VEC always a REC? The question has come to me a number of times since the E 2600-10 vapor encroachment screening standard was published by ASTM last month. The answer emphatically is NO.

First of all, it should be clear that a REC determination can only be made as part of an E 1527 Phase I. The REC definition in E 1527 does include consideration of hazardous substances and petroleum products that may encroach upon a property irrespective of their form (solid, liquid or vapor). The E 2600-10 standard provides a methodology that the environmental professional can use to evaluate the potential for vapors to encroach upon a property (referred to as a vapor encroachment condition or a VEC).

Secondly, if a VEC does exist, the environmental professional conducting the Phase I will have to determine whether or not this VEC constitutes a REC. One way of deciding whether or not a VEC constitutes a REC is to recognize that RECs do not include de minimis conditions, defined in E 1527 as conditions that do not present material risk of harm to public health and the environment, and would not be subject to enforcement action by the regulatory agency. If a VEC meets any of these "de minimis" conditions, the VEC would not likely be viewed as a REC.

Let me use some examples to illustrate the point.

(1) A VEC may exist because of groundwater contamination on the target property or near it, but it may not be a REC (under the de minimis clause) because the depth to groundwater is very deep, i.e., greater than the critical distance (defined in E 2600-10).

(2) A VEC may exist because of groundwater contamination on the target property or near it, but a REC may not exist (under the de minimis condition clause) because the distance between the nearest edge of the contaminated plume and the nearest structure may be considerable, i.e., greater than the critical distance (defined in E 2600-10).

(3) A VEC may exist because of groundwater contamination on the target property or near it, but a REC may not exist (under the de minimis condition clause) because the concentration of the contaminant in the groundwater is below the risk screening level for that contaminant as specified in the state's vapor intrusion guidance policy.

(4) A VEC may exist because of groundwater contamination on the target property or near it, but a REC may not exist (under the de minimis condition clause) because the building has been designed to be intrinsically safe from chemical vapor intrusion, i.e., there is no direct pathway for migrating vapors to reach human receptors.

These examples can provide some insight into how the environmental professional conducting the Phase I might use the de minimis condition clause in the REC definition to help determine whether or not a VEC constitutes a REC.

Vapor Migration and "Old" Phase Is (8 Comments)

Sun, 03 Oct 2010 23:34:33 +0000

Entry by abuonicore

The new ASTM vapor encroachment standard (E 2600-10) that was published a few months ago indicates that under the REC definition in the ASTM E 1527 Phase I standard, as well as under CERCLA and AAI, contaminant vapor migration on or to a property needs to be considered in property due diligence, analogous to contaminated groundwater migration. The only stipulation in the REC definition is that the contaminant be a hazardous substance or petroleum product.

This may represent a potential problem for the industry because of the millions of Phase Is conducted prior to the E 2600-10 standard when vapor migration was not typically considered under the REC definition. The question now is how might EPs respond to this potential liability problem, i.e., a vapor intrusion issue surfaces today on a property where they conducted the Phase I investigation some time ago and did not consider vapor migration under the REC definition.

In my view, there are a number of possible responses. First of all, I believe a strong case can be made that good commercial practice in the Phase I industry did not typically consider vapor migration and potential intrusion into buildings on a property involved in a real estate transaction. Moreover, a screening methodology to evaluate vapor migration did not really exist until recently. A second point that can be made is that EPA's Hazard Ranking System (HRS) used to identify and rank CERCLIS sites for inclusion on the National Priorities (Superfund) List did not in the past and does not to this date consider the risk presented by vapor intrusion caused by migration of subsurface hazardous substances, although EPA is currently evaluating amending the HRS to include such consideration. A logical argument can therefore be made that vapor intrusion risk is relatively new, and that as our understanding of this risk improves, so does our way of evaluating it. Such clearly was not the case "in the past" when these "old" Phase Is were done. Other points that might be made include the fact that an E 1527 Phase I is only "current" up to the date of the investigation. Certainly, there is the possibility that the event leading to the vapor intrusion problem today may have occurred after the Phase I investigation was conducted. For example, there may not have been a dry cleaner and the associated PCE release in the adjacent shopping center when the Phase I investigation was performed. Finally, it may also be possible, depending on the particular circumstances, to use the fact that an ASTM E 1527 Phase I excludes consideration of indoor air quality, and that vapor intrusion is directly related to a building's indoor air quality. Unfortunately, this exclusion does not address the potential for vapor migration onto a property (an objective of E 2600). Rather, it focuses solely on vapors in the subsurface of a property migrating into a building and causing an indoor air quality problem. As such, the potential for vapor encroachment on a property would not be excluded (under the REC definition), only the evaluation of whether or not the "encroaching" vapor can migrate into a building on the property and cause a health risk.

Is there any other reasoning that might provide a defense to potential Phase I consultant liability associated with not considering vapor migration in "old" Phase I investigations?

New ASTM Standard on Vapor Encroachment Screening Published

Thu, 17 Jun 2010 18:29:56 +0000

Entry by abuonicore

On June 14, 2010, ASTM published E 2600-10, Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions. This standard replaces E 2600-08 published in March of 2008.

The newly revised standard focuses solely on screening for the likelihood of migrating vapors volatilized from a contaminated source to encroach upon the subsurface of a property involved in a real estate transaction and create a vapor encroachment condition (VEC). Two tiers for screening are included in the practice. The first tier is based upon the existence of known or suspect contaminated sites in the area. The second tier is more comprehensive and investigates specific characteristics associated with the contaminated plumes from these sites, or if no plume information is available, relies on sampling. If the likelihood exists for vapors to reach the subsurface of the property, further investigation that is beyond the scope of this practice would be necessary to determine if vapor intrusion is occurring into any buildings on the property.

Of particular note in the standard is the completely revised Legal Appendix that discusses the relationship between this standard and the E 1527-05 Phase I standard. In simple terms, the E 1527-05 standard (which complies with AAI) includes in its REC definition the EP's need to consider hazardous substances and petroleum products on the target property or migrating to the target property no matter what form these substances take, i.e., solid, liquid or vapor. The E 2600-10 standard merely provides a methodology for the EP to accomplish this for vapors. If vapors can reach the target property (thereby creating a VEC), the EP conducting the E 1527-05 Phase I would then have to decide whether or not the VEC constitutes a REC. This would be analogous to the EP finding in the Phase I investigation the potential for a contaminated groundwater plume to reach the target property. The EP would then have to determine if this situation is a REC.

It is anticipated that the screening under ASTM E 2600-10 will eventually become a routine part of an AAI-compliant Phase I environmental site assessment. A number of institutions such as HUD already require their consultants to consider vapor encroachment onto the property in their Phase I investigations.

Modeling for VIC Assessment (1 Comment)

Wed, 13 May 2009 12:04:39 +0000

Entry by abuonicore

I have often been asked about the role of modeling in conducting a VIC assessment (Tier 3 in E 2600-08) and how it compares to conducting indoor air sampling. Is there anyone who would argue against the fact that the only way to really know if a problem exists is by conducting indoor air sampling?

Unfortunately, developing an acceptable indoor air sampling protocol is not as simple as it may sound. An acceptable protocol must be designed to collect representative samples. However, the problem is that experience has shown indoor air sampling results can exhibit temporal and spatial variability, and be impacted by indoor activities, building materials and operations, indoor product and chemical usage, and chemicals in the ambient air. To get a handle on all these "background" confounding factors, if it is even possible, can take considerable time and involve significant cost.

Also, it is not even possible to conduct indoor air sampling if the property involved in the real estate transaction has not yet been developed and no structures exist.

As such, there is a role for modeling, e.g., use of a Johnson-Ettinger type model or even an empirical-type model. However, understanding all of the assumptions and default values used in any model is absolutely critical. Unfortunately, there is no perfect model. While models may not be able to definitively determine absolute indoor air concentrations, they can be valuable tools to assess relative impacts, such as what might be experienced if building or soil characteristics are changed or a paved parking lot is added around a structure.

In the final analysis, it definitely makes sense to use a "multiple lines of evidence" approach. In view of all the uncertainty, it also is understandable how a client may instead choose to pre-emptively install a mitigation system.

I would be interested in hearing about your experiences with indoor air sampling and the use of vapor intrusion models for VIC assessment.

Oregon Issues Vapor Intrusion Assessment Guidance

Wed, 31 Mar 2010 19:16:57 +0000

Entry by abuonicore

The Oregon Department of Environmental Quality has just finalized its Guidance for Assessing and Remediating Vapor iNtrusion in Buildings. The document can be viewed and downloaded at:

http://www.deq.state.or.us/lq/pubs/docs/cu/VaporIntrusionGuidance.pdf

EPA 2002 Draft Vapor Intrusion Guidance To Be Finalized?

Thu, 04 Mar 2010 19:47:25 +0000

Entry by abuonicore

There is no question that EPA’s 2002 draft vapor intrusion guidance has significant limitations. It contains a number of outdated toxicity values for assessing risk to humans from chemical vapors in the indoor air. It does not address how to mitigate vapor intrusion risks or monitor the effectiveness of mitigation efforts. It does not clearly recommend a multiple lines of evidence approach, the current-state-of-the-art in the field, to assessing vapor intrusion, and it does not respond to assessing vapor intrusion risks associated with petroleum releases at underground storage tank sites.

On EPA's defense, the Agency has on numerous occasions stated that the 2007 ITRC guidance addresses many of the issues that EPA would have addressed in a final guidance. Moreover, more than half the states have issued their own vapor intrusion guidance, along with the Army, Navy and Air Force. Even the Post Office has its own vapor intrusion guidance. In responding to mitigation questions, EPA often references the New York and New Jersey vapor intrusion guidance documents.

Notwithstanding, OIG, in a report issued in December, recommended, among other things, that EPA needs to: (1) identify the portions of their 2002 draft guidance that are still valid and those that need to be updated; and (2) issue final vapor intrusion guidance that includes updated toxicity values, the need for a multiple lines of evidence approach, addresses petroleum hydrocarbon vapors, identifies when or whether pre-emptive mitigation is appropriate, and addresses what O&M is appropriate for mitigation systems and when institutional controls and deed restrictions are appropriate. EPA OSWER in response to these recommendations indicated that (1) should be completed this summer and (2) by the fall of 2012. Progress at last!

DOD Vapor Intrusion Handbook Released (3 Comments)

Thu, 16 Apr 2009 13:24:23 +0000

Entry by abuonicore

On April 3, 2009, DOD released its Vapor Intrusion Handbook (dated January 2009). The handbook was developed by the Tri-Service (Departments of the Air Force, Army and Navy) Environmental Risk Assessment Work Group to serve as a resource for remedial project managers who may need to investigate the vapor intrusion pathway on both active and closed Air Force, Army, Navy and Marine Corps bases, as well as Formerly Used Defense Sites (FUDS). This is a excellent handbook with a significant amount of information, including well-prepared sections on sampling and analysis, health risk assessment, and mitigation measures. You can access the manual on the web at: https://www.denix.osd.mil/.

Note: If you click on this web address, you may get a notice that the site's security certificate has a problem. You can still click to proceed to the site and this will bring you to DOD's "Announcements" page. Click on "DOD Vapor Intrusion Handbook" to download the actual handbook.

Confusion With Distances in ASTM E 2600-08 (4 Comments)

Mon, 22 Jun 2009 20:28:29 +0000

Entry by abuonicore

There has been considerable confusion over the distances in the screening tiers of E 2600-08. The distances in Tier 1 relate to establishing the area of concern. They are measured from the initial source of known or suspect contamination, e.g., a dry cleaner or a gas station with leaking underground storage tanks, to the nearest structure on the target property. Information is extracted directly from the Phase I investigation to conduct this screening. Just because a source is within the area of concern does not mean there is a vapor intrusion problem, only that it is possible and further investigation is necessary. The further investigation is described in Tier 2 screening. At the Tier 2 level, either detailed information related to the source of contamination and the contaminated plume is reviewed (typically via a state regulatory file review), or invasive sampling, such as soil gas sampling, is conducted. The distances in Tier 2 relate to the distance between the edge of a contaminated plume and the nearest structure on the target property, e.g., critical distance. If the contaminated plume is within the critical distance criteria in E 2600, then contaminant concentrations have to be compared with generic state screening levels or site-specific risk-based screening levels. Only after conducting this level of investigation, is it possible to assess whether or not there is the potential for a vapor intrusion problem. If the potential exists, only a full scale vapor intrusion investigation (referenced in Tier 3 of E 2600) would be able to confirm that a vapor intrusion problem does indeed exist. Such an investigation will usually follow vapor intrusion guidance, policy or regulation established by the state where the target property is located, and E 2600 refers the user to such guidance, policy or regulation. As an alternative to this more comprehensive and costly investigation, it is possible to proceed directly to mitigation.