Accredited Environmental Technologies, Inc.         

1-800-969-6AET                           www.aetinc.biz



What's That Smell?  Vapor Intrusion

Odor/No Odor, Health Concerns


Know Your Property's Site History

Don't Forget Your Neighbors

Site Redevelopment Mitigation



Quotes for the Month


"Teamwork divides the task and doubles the success"

"It is amazing what can be accomplished when no one cares who gets the credit"
Robert Yates

"Individual committment to a group effort - That is what makes a team work, a company work, a society work, and a civilization work"
Vince Lombardi




WHAT'S THAT SMELL? Vapor Intrusion (VI)

     Vapor intrusion refers to the process by which volatile organic chemicals (VOCs) migrate from a subsurface source into the indoor air of overlying buildings. VI occurs when gases from contaminated soil or groundwater seep through cracks and holes in foundations or slabs of buildings and accumulate in basements, crawl spaces or living areas (similar to how radon gas enters the building).

     VI can occur whether the building is old or new, or whether the building is constructed on-grade or worse case has a crawl space or basement. In most cases, operation of the building's HVAC system and large mechanical appliances (exhaust fans, dryers, etc.) exacerbate the problem by increasing the pressure differential.

Odor/No Odor, Health Concerns

     Odors resulting from VI occur primarily from VOCs such as petroleum products (gasoline or diesel fuel) or solvents used for dry cleaning and industrial uses such as TCE and PCE. VOCs are drawn into the building due to differences between the interior and exterior pressures, mix/build-up in the indoor air and expose building occupants through inhalation.

     Each VOC has an odor threshold (range which odors are perceived). In general, most odor thresholds are significantly (orders of magnitude 10-100 times) below the OSHA PEL standards and provide warning to building occupants of a potential problem. In the case of strong petroleum odors, some people can experience eye and respiratory irritation, headache, and nausea.


Do not rely on the odor threshold to provide ample warning. Some VOC's are linked to cancer. Further, OSHA PEL's are for occupational exposures (8 hours per day, 40 hours per week); not continuous low levels that may be found in residential settings where children can be affected.

Standards (Federal, State, ASTM Guidelines)

     VI is increasingly a key emerging focus of federal and state regulatory agencies regarding site redevelopment. VI is a Phase II ESA concern addressed in 39 states. Seven states (CA, PA, NY, NJ, MA, CT, NH) have codified VI in a regulation or law. In March, 2008 ASTM published a VI Standard Practice (E2600-08) entitled Assessment of Vapor Intrusion on Structures Involved in Real Estate Transactions.

     The ASTM Standard Practice specifies a four-tiered screening process to identify whether a property has a VI potential.

Tier 1 - Non-numeric screening

: Formulation of a professional opinion by an environmental professional of no further action based on historical research and site reconnaissance that there are no sources of contamination within the property (typically based on a distance of less than 100 feet).

Tier 2 - Numeric Screening:

Verification of no further action by the collection of soil gas and groundwater samples for comparison to applicable government risk based concentrations.

Tier 3

- Site specific Screening: Air sampling and predictive modeling to assess VI potential.

Tier 4

- Mitigation: Design and implementation of institutional and engineering controls to minimize and/or eliminate VI into the building.

     State regulations on VI vary significantly from state-to-state. One example are the toxicity values for groundwater and indoor air used to take action. The PCE toxcity value for groundwater in ug/L is 1 (for NJ), 25,000 (for MI) and 42,000 (for PA). In 2010, the EPA is expected to provide new technical guidance to minimize these inconsistencies.

Know Your Properties Site History!

     Facility owners, real estate developers and buyers are provided critical site history information in Phase I ESAs. Look for evidence of underground storage tanks, aboveground storage tanks, impoundments/lagoons, underground piping systems and previous manufacturing/chemical use. Floor drains in chemical use/storage areas, floor or soil staining and odors are also signs of potential future VI problems and the necessity for a follow-up Phase II ESA.

     Famous Case - Kiddie Care Day Care

: This daycare was opened in 2004 after a change of ownership and a fresh coat of paint. In 2006 it was closed after NJDEP found up to 100 children exposed to dangerous mercury vapors (as the property was previously used as a thermometer factory). Even now, over 3 years later, the site remains abandoned behind a fence with a locked gate awaiting demolition and remediation which is stalled by litigation.

Don't Forget Your Neighbors!

     Groundwater contamination from buried waste, spills, improper disposal and leaking USTs can travel long distances. Tier 2 or Tier 3 sampling of soil gas and groundwater should be performed to determine if the source of contamination is from your site, adjacent sites or both.

Potential Problem Neighbors include:

Manufacturing sites, especially with chlorinated solvents
  • PCB dry cleaners
  • Fuel Spills (gas stations, tank farms, refinieries, etc.)
  • Brownfield sites
  • RCRA and Superfund sites
  • Landfills

Site Redevelopment, Mitigation

     AET helps its clients deal with the technical, regulatory, and risk communication challenges presented by VI. AET's staff has proven expertise in providing accurate and efficient testing of both groundwater and indoor air and recommending cost effective mitigation systems.

  1. Existing Occupied Buildings: VI is a evaluated as a source/pathway during odor investigations. Care is taken to eliminate stored chemicals and other interior building sources to determine background levels. Modifications to the buildings HVAC system and source/pathway controls are implemented.
  2. Abandoned Buildings: Redevelopment usually entails demolition of existing site structures followed by source minimization. Institutional controls are implemented to notify future buyers, developers and construction employees of the existing contamination (in the form of a deed restriction). Redevelopment will also include special construction techniques similar to radon to minimize/eliminate VI issues.

     Recent NJDEP Changes:

In August, 2009 NJDEP changed its VI investigation requirements for sensitive populations such as child-care centers, schools, and residential properties. NJDEP now requires both sub-slab soil gas and indoor samples whenever groundwater data exceeds the NJ Groundwater Screening Level. Indoor air samples must be collected first followed by the collection of sub-slab soil gas samples within the next 24 hour period.

     2009 Case Study:

AET completed a Phase II ESA at an abandoned industrial property containing a drycleaning plant. Soil and groundwater sampling identified Perchloroethylene (PCE) as the chemical of concern. AET prepared project specifications for environmental remediation and demolition of site structures and project management during remediation/demolition work. VI issues were addressed by Tier 3 Screening. The PADEP granted Release of Liability for this property which is currently awaiting redevelopment as a banking facility.


Make AET your first point of contact for your environmental consulting. 

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Alan Sutherland has been a Certified Industrial Hygienist since 1978 with over 30 years of CIH-related environmental consulting experience. He has a Masters Degree in Environmental Science from Drexel University and is the founder/owner of Accredited Environmental Technologies, Inc. (In 1984). He is uniquely trained and licensed as an Environmental Professional in both the field and laboratory. He has been the founder of two AIHA Accredited Laboratories and a mentor to six (CIHs). Mr. Sutherland is also a Certified Hazardous Material Manager. He can be reached directly at 610-891-0114 or email a.sutherland@aetinc.biz.

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