EnviroForensics’ Use of HAPSITE Technology Allows for More Accurate Vapor Intrusion Inspection

Correctly assessing the Vapor Intrusion (VI) exposure pathway is a complex process, which is rarely straight forward. When VI does occur at or near hazardous material cleanup sites, it rarely results in a constant stream of contaminants into the breathing zone.  Rather, there are many variables that affect the way vapors move from the subsurface into a structure.  Daily and seasonal temperature fluctuations result in variable pressures within and beneath buildings that change VI conditions. The amount of precipitation that falls also affects vapor intrusion rates, and can at times temporarily stop it altogether.  Building foundation and construction details can affect the pathway that intruding vapors may take once beneath or inside a structure, thereby resulting in a distribution of indoor air contaminants that aren’t intuitively consistent with predictive VI rules of thumb. Complicating things even more is the fact that numerous household products contain the same chemicals that we are trying to assess from below ground contamination.  Taking into account all of these variables to determine if a human inhalation exposure is in existence, or may be in existence at some time during the year, is a highly detailed and specialized process.

Fortunately, the VI team at EnviroForensics maintains a line of highly specialized, field-based, analytical instrumentation that can be used to tease out the necessary details during VI assessments. One of the most highly developed instruments in our arsenal is a portable Gas Chromatograph/Mass Spectrometer, named HAPSITE. The HAPSITE was originally designed by its manufacturer for the U.S. Military and is designed to deliver real time qualitative and quantitative, laboratory-quality results for air samples in the field. The HAPSITE has the capability of identifying and measuring specific volatile organic compounds as low as the parts per trillion (ppt) range. The HAPSITE instrument can be calibrated to measure the ions specific to the contaminants of concern (COCs) at the Site.

The Enviroforensics VI team consists of a certified HAPSITE operator. When operated in ‘survey’ mode, the HAPSITE instrument provides real-time data, depicted as an on-going line graph on the front panel display of the instrument.  We use this survey mode during VI assessments to find specific points in a structure where vapors may be entering the indoor air. We have found that cracks in floors and walls, floor drains, pipe chases, interior wall spaces and attics are all important features to explore. Background sources, such as those common household products mentioned earlier, can also be found hiding in closets, drawers, basement corners, etc. When an area of concern is located, the HAPSITE is switched to ‘run’ mode. This sampling mode collects an air sample that is analyzed by the instrument with laboratory quality, in a short period of time.  This type of real-time analysis allows for adjustments to be made in the field and provides comprehensive conclusions with fewer mobilizations and sampling events.

During any VI assessment, the main line of regulatory thought is that if VI is occurring at any time during the day or year, that worst case exposure condition is used to calculate the occupant’s potential risk. By using highly-specialized instrumentation, such as the HAPSITE, the EnviroForensics VI team greatly improves the odds that we can interpret all of the variables that are part of VI assessments and properly report true exposure conditions.

About the Authors:

meganhamiltonmain-137x137Megan Hamilton
Risk Assessor and Vapor Intrusion Specialist


Ms. Hamilton has over fifteen years of experience in environmental regulatory oversight and consulting, with a focus on risk assessment and vapor intrusion expertise. Her diversified professional experience includes research, policy development, technical writing, public outreach, vapor intrusion investigation and remediation, data analysis and interpretation, human health risk assessment, and conceptual site model analysis. Ms. Hamilton served as a technical, scientific, and risk assessment policy resource for the Indiana Department of Environmental Management’s (IDEM) Office of Land Quality for nine years. She also served as the coordinator and team leader for the IDEM Vapor Intrusion Workgroup for six years and is the main author of the current Indiana Vapor Intrusion Guidance. She has helped design and implement numerous vapor intrusion investigations for chlorinated and petroleum contaminated sites throughout Indiana.  Ms. Hamilton is experienced in evaluating human health risk assessments, as well as vapor intrusion risk assessments for sites regulated by all of IDEM’s remediation programs, including:

  • Brownfields Program
  • Leaking Underground Storage Tank Program
  • RCRA Program
  • State Cleanup Program
  • Voluntary Remediation Program

Ms. Hamilton develops, helps implement, and oversees the VI investigations and mitigation for all of EnviroForensic’s projects. She is also the main contact for risk communication issues and community outreach development. Ms. Hamilton has presented at several National Conferences, is a member of the National EPA VI Science Advisory Committee, and currently serves on the Board of Directors for the Midwestern States Environmental Consultants Association (MSECA).

mainjeffJeff Carnahan, L.P.G.
Vice President, Chief Technical Officer


Jeff Carnahan is a Licensed Professional Geologist (LPG) with over 17 years of environmental consulting and remediation experience.  Mr. Carnahan’s expertise has focused on the investigation and interpretation of subsurface releases of hazardous substances for the purpose of evaluating and controlling the risk and cost implications to his clients.  While managing sites ranging in size from retail gas stations and dry cleaners to large manufacturing facilities, Mr. Carnahan has amassed extensive experience working with releases of chlorinated solvents within voluntary and enforcement cleanup programs for various State agencies and the U.S. EPA. Throughout his career Mr. Carnahan has provided technical support to the legal community regarding the cause, origin, transport and potential cost of environmental releases. Additionally, Mr. Carnahan has over 13 years of experience in the investigation and mitigation of vapor intrusion issues and leads the VI Assessment Team at EnviroForensics. His experience and insight make Mr. Carnahan uniquely qualified to advise his clients on potential environmental liability issues and cost implications.





Cradle to Grave Environmental Responsibility and Long-Tail Liability

“Cradle to Grave Responsibility” and “Long-Tail Liability” are terms that greatly affect anyone who purchases, handles or manages hazardous substances. Cradle to Grave Responsibility refers to the fact that any person who generates a hazardous waste material is responsible for that waste from the time it is generated until the end of time. With that being said, some hazardous substances tend to stick around for longer periods of times than others, including chlorinated solvents (solvents commonly used in dry cleaning and manufacturing operations such as PCE and TCE). Because there is no statute of limitations that relieves someone of this long-term responsibility, the management of hazardous substances is a Long-Tail Liability.

The responsible party (RP) in these situations is any individual, or business entity, who owns or operates a facility that is impacted with hazardous substances, or anyone who accepts any hazardous substances for transport to a facility if the transporter selected the facility. When the RP is no longer physically, financially or administratively present the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA, which is commonly known as Superfund) applies to determine liability. CERCLA may require that the Federal or State government cleans the contamination at the site and later approaches other RPs to reimburse those costs, or RPs may have the chance to offer their own cleanup approach beforehand.

An RP has different options when a settlement demand or lawsuit is filed for contribution by the government. Ignoring the suit or demand is not recommended, since the government can be very tough on those who choose to do so. The best option for an RP is to hire a consultant to help evaluate their liability and then investigate and remediate the contamination, if necessary. If active remediation is actually needed, it is possible that an RP can use historic insurance policies as a source of funding the environmental work.

In his article from the September 2013 issue of Cleaner and Launderer entitled “Cradle to Grave Responsibility and Long-Tail Liability,” Stephen Henshaw, President and CEO of EnviroForensics, discusses these options and offers his expert advice. He also suggests ways to deal with Long-Tail Liability to help protect individuals and companies managing hazardous substances.

New Wisconsin DNR Guidance is Defining Long Term Obligations

You have probably seen previous articles by EnviroForensics talking about the importance of a well-defined investigation and remediation due to the potential long term stewardship responsibilities and costs that could be incurred following cleanup activities.  Those potentials are now becoming reality, since just this month the Wisconsin Department of Natural Resources (WDNR) released two guidance documents on this topic.  The first is an internal DNR guidance document, RR-5474, Vapor Intrusion Continuing Obligations Applied in DNR Closure Approvals.  RR-5474 addresses DNR processes specific to closure approval letters.  The second is a companion document, RR-042, DNR Case Closure Continuing Obligations: Vapor Intrusion, which speaks to responsible parties and environmental consultants, and provides information for completing the necessary Case Closure-GIS Registry Form 4400-202.  These new documents describe the application and implementation of these vapor intrusion continuing obligations and are applicable at sites closed with residual contamination left in place in order to prevent exposure from the vapor intrusion pathway.

You may have been directed by the WDNR to conduct investigation and remediation for the release of tetrachloroethene (perc) or other chemicals.  Much attention in the past few years has been given to vapor intrusion and mitigation if a release of perc has been found.  Vapor mitigation (exposure control) often has been in the form of a sub-slab depressurization system, or SSDS for the short term.  These systems, while effective at temporarily stopping vapor intrusion or preventing it from happening, are often forgotten pieces of the investigation and remediation puzzle once closure is attained.  In a very formal way the WDNR has now said vapor intrusion mitigation systems can no longer be forgotten relics of the investigation past. They must be maintained and monitored into the future.

Both WDNR documents contain contaminant level considerations that WDNR staff, contaminated site owners, or consultants may use to make decisions for applying vapor intrusion continuing obligations.

How do these new guidance documents affect you?  Well, if you are approaching the point of closure, you and your consultant should reference RR-042 and the included table, “Considerations for Applying Vapor Intrusion Continuing Obligations”, to determine which continuing obligations will be required by the WDNR. They may even dictate continuing obligations prior to approving the remedial action.

By the time closure is anticipated following remediation, all vapor intrusion pathways and ongoing mitigation should be fully understood and all involved parties fully engaged (i.e. off-site property owners with SSDS installed.  However, by thoroughly evaluating and remediating to a greater extent, the need for continuing obligations for the vapor intrusion pathway may be eliminated.

Once you have completed your investigation and remediation to the extent possible and you have submitted your Form 4400-202 for case closure, the DNR will review the proposed closure and the need for continuing obligations as guided by RR-5474.  Should the DNR find a deficiency in the proposed closure continuing obligation plan, they may deny closure or make closure contingent on additional continuing obligations.  These may include operation and maintenance of vapor mitigation systems, additional monitoring, or property use restrictions until such time it can be demonstrated that the potential exposure is no longer present.

The continued operation of vapor mitigation systems or additional testing can be costly over time.  As written, the WDNR documents indicate costs associated with continuing obligations will be incurred by the individual property owner, which may represent long term liabilities for the responsible party.  Currently the DERF does not provide a mechanism to fund activities beyond closure.  In fact the guidance indicates formal changes to continuing obligations, land use changes, and removal from the GIS registry may in some cases cost several thousand dollars per off-site property.  As such, alternative funding sources may be necessary to manage these costs.

In the end, the best approach is to eliminate as many long term obligations through detailed assessment and adequate remedial actions.    When making short and long term decisions for your site, consider all scenarios prior to accepting a long term continuing obligation for your closure.  Keep in mind that DERF funds are limited and the DNR’s ability is limited in approving remedial efforts that are aggressive enough to minimize costly continuing obligations.  If you think that you may incur such post-closure costs, please don’t wait until a remedy has been approved by DERF to start seeking alternative funding.

About the Author:

robcolorthumbRob Hoverman, L.P.G.
Regional Manager, EnviroForensics Wisconsin Office

Mr. Hoverman is the Wisconsin Regional Manager and a registered professional geologist with more than 14 years of professional environmental services with a focus on contaminated site management.  Mr. Hoverman currently serves as senior project manager for several projects in Indiana and Wisconsin.  His diversified professional experience includes research, scoping and budgeting, project management, data analysis and interpretation for both hazardous and non-hazardous substances, including compounds such as chlorinated solvents, petroleum related constituents, as well as metals.  Mr. Hoverman has managed numerous investigation and remediation projects regulated by state programs, and his responsibilities involved every aspect of projects from proposal preparation through project closure, regulatory negotiations and stakeholder communications.  Beyond technical evaluation and interpretation duties include obtaining contract approval, job initiation, budgetary analysis, budget tracking, and subcontractor contracting and management.  Mr. Hoverman has also served as technical support for numerous vapor intrusion including soil gas, sub-slab, indoor air sampling and mitigation.  As the Regional Manager for EnviroForensics, Mr. Hoverman maintains momentum and resources for Wisconsin projects.

EnviroForensics Obtains Site Closure on Another Environmental Matter

EnviroForensics was recently able to achieve regulatory closure from the State of Indiana and the Indiana Department of Environmental Management (IDEM) for a valued dry cleaner client in Jasper, Indiana. Our client has shown immense gratitude that this issue has been cleared up as quickly as it has. She is looking to sell the business and with this NFA status, she will be able to move forward and finalize the sale.  This adds to a growing list of closures which we have obtained for our clients, allowing them to move past their environmental liability and utilize their property for its highest value, unencumbered from contamination and stigma.

We take pride in assisting our clients with all facets of an environmental investigation – from the initial response of contamination being detected, to investigation of the site, all the way to remediation and subsequently, site closure. We handle this all while helping our clients utilize their past insurance policies to pay for the costs of such work. Perchloroethylene (Perc) and other chlorinated solvents are complicated in nature and makeup, and due to this are difficult to clean up. That being said, EnviroForensics has obtained more regulatory site closures of sites contaminated with dry cleaning and chlorinated solvents than any other company in the Midwest.

About the Site

Our client began their operation in 1997 after converting the property from an ice cream parlor; there was no evidence found in historical records of dry cleaning operations prior to our client. Contamination was discovered late 2012, as Perc was detected in soil and groundwater samples collected from beneath the building. Under a demand for action by the IDEM, and under their oversight, the investigation and characterization of the site began. Of some concern during our investigation was the close proximity to a river. However, following our last investigation in January 2014, we concluded that minimal chlorinated concentrations in soil and in the initial water-bearing zone are isolated to a small area beneath the site near the current dry cleaning machine.

Using multiple lines of evidence we were able to prove that the contaminants were not migrating through groundwater or preferential pathways to offsite receptors or to the river.  Based on this information, we requested that the IDEM approve Site Characterization and recommended that the site pursue an Environmental Restrictive Covenant.  The IDEM responded in May 2015 stating that no further response actions are necessary and the site is available for closure.