Comments
Wouldn't you consider this abutting former gas station with known releases as already creating a REC on the target property, irrespective of vapor migration concerns? A Phase II certainly would make sense, and I would add soil gas testing to the scope of work to check for vapor migration.
Remember, the objective of the Phase I is to identify RECs. Generally speaking, if a known or suspect nearby contaminated site is believed to create a vapor encroachment condition (VEC) on the target property, then the EP would need to determine if this VEC is then creating a REC on the target property. In your case, the nearby contaminated site would already be creating a REC on the TP. Hence, the issue is mute. All that needs to be done is to add to the Phase II sampling a check for vapors in the subsurface.
If you install a properly engineered chemical vapor barrier below the building, that should eliminate the vapor intrusion concern; however, you would still need to do the Phase II sampling because there may yet be petroleum contamination on the property from the abutting former gas station. Hence, to answer your question, it would be prudent to still do the sampling.
Bill, this same logic applies to the distances in the E 1527 standard. The distances selected in the E 2600 standard are based on 90th percentile plume lengths, which means that certainly there will occasionally (10% of the time) be plume lengths greater than this. Remember that E 1527 and E 2600 are not "absolute" standards with the purpose of totally eliminating risk - if you want to do this you best start sampling! They are meant to be risk management methodologies with a high probability of reducing (not eliminating) risk.
As always, Larry, I respect your opinion and we can agree to disagree. Fortunately, the marketplace will ultimately decide the way it wants to proceed. As a real estate owner, I believe the marketplace will take the approach I outlined, i.e., step-by-step approach screening first and then proceeding further only if a potential issue surfaces. I say this because it is the most cost effective way in which to proceed and my experience suggests that the marketplace prefers this type approach. This includes lenders. Anyway, we shall see!
Larry:
You made a number of excellent points in your
article, including the fact that vapor migration needs
to be considered in Phase Is, that sophisticated property owners and lenders
are revising their Phase I scopes of work to include vapor migration, and that
you anticipate that vapor screening will become a routine part of Phase I
reports. Where we differ is that you believe a Phase I needs to further consider actual
vapor intrusion assessment (vapor migration) into structures on the target property, rather than just the potential for vapors to migrate on or onto the target property. Further, you
state that since federal and state programs are concerned about vapor
intrusion, not vapor encroachment, the E 2600-10 standard does not provide any “meaningful
information to the client.” This simply is not true and can be misleading to
EPs conducting Phase Is.The E 2600-10 standard is meant, as you know, to screen for the potential for vapors
to encroach upon a target property. If the potential exists and the EP considers this a REC, then
further investigation can be conducted to determine if the vapors are impacting
structures on the target property. This is the most cost effective approach. Prior to
the E 2600-10 screening methodology, EPs simply did not have a cost effective methodology
that they could rely on and use as guidance to determine if migrating vapors
could reach a property. You seem to believe that screening makes no sense and
that Phase Is should proceed directly to vapor intrusion assessment, preferably
by including “inexpensive soil gas sampling.” A number of comments are in order
here. First of all, there is virtually no argument in the industry that the E 2600-10
screening methodology is the methodology of choice to determine if more
work needs to be done. The methodology was developed by vapor intrusion experts
and is the most technically sound approach available to conducting such a screening
evaluation. Secondly, soil gas sampling can be quite expensive if it is desired
to produce representative results. This is irrespective of where the soil gas is
sampled, i.e., away from the building or near-slab or sub-slab. The fact is soil
gas sampling results can be highly variable, both temporally and spatially. In
fact, this variability has caused a number of states and EPA to re-evaluate the
use of soil gas sampling alone as a predictor of vapor intrusion, and your
assumption that “soil gas sampling is the only way to know if there is a risk
of vapor intrusion” is misleading.You also note in the article your preference to "presumtively screen-in properties
unless there are specific facts to overcome the presumption.
This is what the old E 2600-08 standard did. Unfortunately,
by doing this, a significant amount of unnecessary and expensive
vapor intrusion assessment work would be performed, the burden of which could
hardly be justified in a commercial real estate transaction.The way E 2600-10 works is that you first screen
using Tier 1 methodology (as part of the Phase I) for the potential
for vapors to reach a target property. If the potential (VEC) exists, the EP
must next determine whether or not this VEC represents a REC (and more often
than not, it does not, and your presumption that “consultants seem to be taking
the view that every VEC should be a REC that requires additional investigation”
is simply not true). If the VEC is a REC, then the EP and client determine what
the appropriate next step is. More than likely, it would be to follow E 2600-10
Tier 2 methodology, which may include soil gas sampling. If vapors are
confirmed on the property, the EP generally will then follow the applicable state’s
vapor intrusion guidance. This is a logical, reasonable and cost effective
approach, and does not put an unnecessary cost burden on the commercial real
estate transaction.
Finally, it is necessary to distinguish between
vapors migrating from off-site contaminated properties to a
target property, and vapors resulting from on-site contamination that impact
the target property and perhaps nearby properties. Virtually all of the cases
that you refer to in the article are in the latter category. According to
E 2600-10, if [volatile] contamination exists on the target property, a VEC already
exists and proceeding directly to Tier 2 methodology (which may include soil
gas sampling) is logical and reasonable. The challenge in the acquisition of
commercial property, however, is dealing with the former category, assessing
the potential for vapors from off-site sources of [volatile] contamination to migrate
to the target property. This is the real value of the E 2600-10 Tier 1
screening methodology, and should not be discounted in your article as
“essentially worthless.”
Tony
Patrick:
The critical distances in the E 2600 standard were based upon Task Group member experience in the field working on many of the major vapor intrusion sites in the U.S. and their published works. In addition, the Task Group was able to rely on the experience of a number of participating organizations, inlcuding EPA, the American Petroleum Institute and the Halogenated Solvents Institute. EPA, for example, had used the 100 ft distance for non-petroleum hydrocarbons, e.g., chlorinated solvents, in its draft 2002 vapor intrusion guidance. I would also refer you to Phil Lowell's and Bart Eklund's publication, VOC Emission Fluxes as a Function of Lateral Distance from the Source, in AIChE's Environmental Progress, Vol. 23, No.1, published in April 2004; Robin Davis's publication, Vapor Attenuation in the Subsurface from Petroleum Hydrocarbon Sources, in LustLine Bulletin 52, May 2006; Tom Hugh's recent excellent summary, Evaluation of Vapor Attenuation at Petroleum Hydrocarbon Sites: Considerations for Site Screening and Investigation, published in the International Journal of Soil and Sediment Contamination, Vol. 19, No. 10, July/August 2010; the extensive modeling work by Lilian Abreu and Paul Johnson, including their 2005 publication in Environmental Science and Technology (Vol. 39, No. 12), Effect of Vapor Source - Building Separation and Building Construction on Soil Vapor Intrusion as Studies with a Three Dimensional Numerical Model; and much more.
The area of concern in E 2600 was established based upon 90th percentile plume lengths from statistical evaluation of thousands of both chlorinated plumes and petroleum plumes across the country. Additional information may be found in "A Smaller Intrusion: Reducing the AOC on the ASTM Vapor Intrusion Standard," published in the May 2009 issue of Pollution Engineering.
Tony
Just a clarification of my comment - when I referred to "ethanol concern" or "vapor intrusion concern" in my comment I meant with respect to Larry's "ethanol having an impact on vapor intrusion" question. Of course, any gasoline spill, with or without an ethanol additive, represents a potential vapor intrusion problem depending on how close nearby structures are.
There is evidence that ethane degrades in groundwater and consumes sulfate that otherwise would have been available to degrade benzene (in BTEX). Hence, benzene plumes will likely be longer in the presence of ethanol. Notwithstanding, let us not forget that ethanol replaced MTBE in 2006. Hence from a vapor intrusion viewpoint, a spill has to be fairly recent for it to present an ethanol concern, and bear in mind that USTs have since the 90s had to meet stringent RCRA requirements for leak detection. The vapor intrusion concern will be much more likely associated with old gasoline station sites that existed prior to (and without) the UST upgrades required under RCRA - when ethanol was not in use.
Larry, you and I will just have to agree to disagree on the views of the legal subcommittee. However, there can be no argument on the outcome of the ballot. There were no negatives, including none from lawyers on your legal subcommittee. If any of them disagreed, they had ample opportunity to vote negative on the ballot.
We will also have to agree to disagree on the value of doing VEC screening. The technical experts on our Task Group believe the VEC screening in E 2600-10 is more than adequate to evaluate vapor migration that may encroach upon a target property. If it does not encroach upon a target property, the likelihood of there being a vapor intrusion problem is nil. If you are aware of specific lawsuits involving contaminated sites that would have been screened out as contributing to a VEC on a target property using E 2600-10 criteria, I would be interested in knowing the specifics, i.e., where the contaminated property was in relation to the target property boundary or where the edge of the contaminated plume was relative to the target property boundary. To my knowledge, no lawsuits exist where E 2600-10 screening would not have worked. Moreover, most involve contamination that is actually on or has reached the target property (which of course would be a VEC under E 2600-10).
You state that you require your EPs to use the E 1527-05 search radii to flag contaminated sites with volatiles used in the past or currently, and if any are within the E 1527-05 search radii, you require soil gas sampling on the target property. You have every right to do this, but I can't see how you do not view this as ultra-conservative. Your consultants must love you as they clearly are doing a heck of a lot of soil gas sampling! In my opinion, if consultants follow this approach on all commercial real estate transactions where Phase Is are done, the commercial real estate industry would be up in arms and these consultants would quickly be out of the Phase I business. One other point I might make is that you are putting heavy reliance on soil gas sampling, which in and of itself has considerable variability. Following your logic and low risk threshold, then, you would likely require a sizeable soil gas sampling investigation, including perhaps even sub-slab sampling. Then again, since soil gas sampling levels as a predictor of indoor air quality levels is tenuous at best, why not go directly to indoor air sampling, and since indoor air sampling has considerable variability as well (time and spatial dependent), I am sure you would want a fairly extensive indoor air investigation! You have to agree that the vast majority of prospective purchasers (other than perhaps your clients) would have a very difficult time accepting this approach if recommended by consultants. I do not mean to go overboard, Larry, but the point I want to make is that the methodology in E 2600-10 is already conservative and if used properly is an excellent methodology (and risk management tool) for screening in commercial real estate transactions.
I think we have discussed the subject ad nauseum. How about we listen to what others think?
(1) The legal subcommittee did reach consensus (per the balloting process) and it was that consideration of vapor migration (encroachment onto a target property) must be considered in an E 1527-05 Phase I REC determination, analogous to groundwater migration.
(2) E 2600-10 has in its title: "vapor encroachment screening on property involved in real estate transactions." There can be no argument that it makes sense for a prospective property owner in conducting due diligence on a property to evaluate the likelihood of vapors to encroach upon the property. If a VEC does not exist, there is little need to be concerned about vapor intrusion problems. If a VEC does exist, then it may be appropriate to investigate further (or even possibly terminate the deal). If a prospective purchaser really wants the property but is concerned about toxic tort claims, then clearly further investigation is in order. Or it may make more sense to just go to pre-emptive mitigation and eliminate the concern.
(3) It is correct that the owner of a property is not liable for cleaning up a nearby VOC-contaminated source impacting his or her property. However, what you can not forget is the fact that there still is an impact on the property and potential costs. For example, suppose the owner of the contaminated site next to the target property (e.g., a former dry cleaner) is no longer around or can't be found? Do you wait for the state to clean it up (which can take years, if ever) and in the meantime, all your tenants leave because they do not want to be exposed to "toxic vapors" and you are unable to attract new tenants because of the stigma on your property? By the way, your tenants may decide to sue you, and even if you are not responsible, you will still have defense costs. And I can go on and on. It should be obvious that getting entangled in a vapor intrusion problem can be costly even if it comes from an off-site source.
(3) There is no one on the legal subcommittee, except for you, as far as I am aware that believes E 2600-10 is "a tool to be used to commodicize the VI process." In fact, this is the first time I have even heard this! E 2600-10 is a technically supportable and conservative methodology that an EP doing a Phase I can use to evaluate vapor migration. An EP does not have to use it if they have an alternative methodology. But the fact is, the legal committee made us all very aware that vapor migration has to be considered in an E 1527-05 Phase I.
(4) In California and other states with risk screening levels, the distances where an assessment must be conducted are related to the distance from the contaminated source (groundwater or soil) to the structure. The distance ("critical distance") in E 2600-10 is from the contaminated source to the property boundary. If E 2600-10 identifies a VEC, then the state risk screening levels would be used IF the nearest potentially impacted structure is within the distance identified in the state VI guidance document. For example, in the VI guidance of many states the assessment process is only initiated if the distance from the contaminated source to the nearest structure is within 100 feet. If it is, the first thing typically required is comparison with the risk screening level appropriate for the contaminated media. If below this level, VI is not a concern (and the VEC would certainly not be a REC under the de minimis provision). If above this level, then the VI investigation must continue. However, a prospective purchaser has many alternatives besides doing further investigation, e.g., for example, he or she can require pre-emptive mitigation to be installed. If rather than a prospective purchaser, you are already the owner of the property (as I believe you are considering in your comment), then the owner of the property has no choice but to do further investigation as he or she can not simply walk away from the deal.
(5) E 2600-10 and the numbers used for screening are very conservative (the opposite of what you imply in your last paragraph). For example, they are based on 90% plume lengths (not average plume lengths). Vapor migration is assumed in vadose zones with relatively permeable soil characteristics. Paths of least resistance for vapor migration are assumed to be directly at the target property.
(6) Finally, if you really believe the distances in E 2600-10 are "not suitable for clients with low risk thresholds," what distances would you advise your EPs to use? I have spoken with hundreds of EPs about the search distances in E 2600-10 and if anything, they believe they are too conservative. To go beyond these distances would clearly involve considerably more work and investigation by the Phase I EP, most of which would be a waste of time. If your clients really have a very low risk threshold, I would suggest that it would be more cost effective to simply do some soil gas sampling on the target property. Remember, E 1527-05 is not an "exhaustive investigation" nor does it "eliminate uncertainty." What it tries to do is balance cost with the value of the information derived. It is really risk management. If you want to eliminate risk, then spend a lot more money investigating the site or buy insurance. By the way, I'll bet you know Superfund site plumes longer than a mile (the search radius in E 1527-05)!
Larry, if Tier 1 screening in E 2600-10 is useful to prospective purchasers as you suggest, it clearly will be useful for lenders since they will essentially be partners with prospective purchasers. Moreover, since they are a key stakeholder in due diligence for commercial real estate transactions, I am sure you will agree that they would want to know if a property represents a potential vapor intrusion problem. This clearly is the reason why HUD and Federal Housing Financing Agencies, for example, require Tier 1 VEC screeining using E 2600-10 methodology in Phase Is performed by their EPs. It is also the reason why more and more banks are making sure that Phase Is consider vapor migration on the target property. I believe that you will be hearing more from lenders on this topic at the EBA meeting in Fort Meyers next month.
The second issue you raise relates to uncertainty in the "vapor intrusion assessment" process. The source of this uncertainty is for the most part related to the difficulty in being able to predict with any degree of certainty indoor air contaminant concentrations from sub-slab contaminant concentrations measured by soil gas sampling. Personally, I believe the real problem here is being unable to isolate confounding factors in the indoor air quality measurements. Lack of understanding of air movement in buildings also contributes to confusion in analyzing results. For example, some consultants do not realize that indoor air can actually "contaminate" sub-slab soil gas, particularly when the building is operating under positive pressure as it often is. Movement from sub-slab to indoor air is NOT a one way street, but rather a two way street depending upon the building pressurization cycle.
Finally, it is important to understand that "vapor intrusion assessment" is really a three step process: (1) Can the vapors encroach upon the target property? (This is where E 2600-10 comes in to play); if so, (2) Can the vapors reach a structure on the target property and migrate inside? (This is where federal and state guidance comes into play); and if so, (3) Can vapors migrating into the structure from the sub-surface cause a health problem to human receptors inside the structure? (federal and state guidance also comes into play here). E 2600-10 is focused on vapors migrating onto the target property. Federal and state guidance is focused on vapors migrating into structures on the target property. These are two very distinct assessments. When discussing issues, it is essential that reference be made to the specific step in the vapor intrusion assessment process that is being impacted.