The Soil Gas Safe Communities study is a jointly-led study funded by the Environmental Protection Agency (EPA). Researchers from RTI International and Jacobs are working in collaboration with local government and community members to conduct pioneering research to better understand the indoor air quality and potential sources of indoor air contamination in your neighborhood.
We are developing a new concept to quickly identify indoor contaminants of concern that may be entering buildings from contaminated soil gas beneath homes and buildings in communities. The results can then be used to inform health and safety risks at a community scale and identify actions you and your neighbors can take to improve indoor air quality.
Study Team
RTI International (www.rti.org) is an independent nonprofit research institute dedicated to improving the human condition. Our vision is to address the world's most critical problems with science-based solutions in pursuit of a better future. RTI is leading the Soil Gas Safe Communities method development and pilot testing along with our subcontractor Jacobs.
Jacobs (www.Jacobs.com) is a large engineering firm with extensive field experience in vapor intrusion sampling and analysis. For this study, vapor intrusion experts are helping to design and test the Soil Gas Safe Communities concept. Local field staff will place indoor air samplers in homes to measure concentration of volatile organic chemicals and radon gas.
Consent and Privacy Policy
Written consent to participate in the study will be obtained before collecting soil gas and indoor air samples on private property. This consent is referred to as an access agreement and is signed by the homeowner and a primary resident.
Property records will be used to identify buildings within a community's study area. Names and addresses in the property records are public information. Any information about household members and behaviors not included in property records will be kept anonymous.
We will use a unique identification number for each building included in the study and will aggregate sampling results by a defined area (e.g., by street) when sharing results outside of the study team. Sampling results, along with next steps or recommended actions, for individual homes will be shared directly with the homeowners/residents after the samples have been analyzed.
About
Why is this important? The biggest challenge to characterizing vapor intrusion is the spatial (area) and temporal (time) variability in the concentration of contaminated soil gas that may enter a building. The conventional approach used to fully characterize vapor intrusion relies on collecting distributions of frequent and continuous soil gas concentration data from every building 'at risk' for vapor intrusion over many months. These activities are costly, time consuming, can be intrusive to building occupants considering the number of indoor samples to be collected, and stigmatizing to certain neighborhoods and residences where vapor intrusion is confirmed. Oftentimes, there is limited input from community members regarding decisions related to their personal risk to vapor intrusion.
The EPA is conducting pioneering research to address the challenges associated with traditional methods of vapor intrusion characterization through the Soil Gas Safe Communities study. We will use indicators, tracers, and surrogates for volatile organic compounds that have been suggested as a potential solution for making the vapor intrusion pathway assessment and long-term monitoring more informative, efficient, and cost-effective. The indicators, tracers, and surrogates being used for the Soil Gas Safe Communities study include temperature, pressure, and radon gas. We will be working directly with community members to collect indoor air samples with the intent of reducing indoor chemical sampling requirements while maintaining acceptable confidence in exposure characterization.
Vapor Intrusion of Soil Gas
Soil gas is the gas underground between solid soil particles. It is above the water table and can be contaminated with volatile organic compounds (VOCs), such as dry cleaning solvents or gasoline, resulting from a chemical spill, leak or improper disposal. Naturally-occurring sources such as radon, may also contaminate soil gas.
Depending upon each building's construction and ventilation, soil vapors can rise through small cracks in foundations and other openings into the building. This migration-exposure pathway is called vapor intrusion.
Vapor intrusion refers to the migration of vapor forming chemicals from a source, such as contaminated soils or groundwater, to a receptor such as homes, schools, commercial buildings, or other enclosed spaces.
The EPA and other organizations have published a lot of information about vapor intrusion migration pathways, risk of exposure, and recommended actions to mitigate exposure risks. Please visit https://www.epa.gov/vaporintrusion for more information.
Soil Gas Safe Communities Study
The Soil Gas Safe Communities study is a new concept developed by the EPA that aims to inform and involve community members about their risk of vapor intrusion of contaminated soil gas. This study will be completed in phases.
The first phase will examine the protectiveness of using indicators, tracers, and surrogates that act like VOCs in terms of their migration pathways into buildings. We will develop this new method and compare the results to the traditional exposure assessment process. This phase is expected to be completed by November 2024.
The second phase will pilot test the new method. We will train community members on how to use simple equipment to collect the indicators, tracers, and surrogate data inside their homes. The community members also will be trained on how to interpret results. This phase is expected to be completed by June 2025.
The results from the study and method development will be evaluated to determine the overall effectiveness of the Soil Gas Safe Communities concept.
Soil gas safe - Soil gas safe building conditions refer to low soil gas and indoor air concentrations of anthropogenic or human-made vapors that have been tested and are below or have been mitigated below regulatory levels. This may include an area where primary VOC concentrations are known through community monitoring, and most buildings where VOCs exceed the regulatory screening levels have been assessed and mitigated, as needed.
Community - A community can have many definitions considering place or geographic boundaries, common interest, circumstance, as well as a group of people who come together and advocate for change. A community may extend beyond the boundaries of a plume and can impact multiple neighborhoods.
Soil Gas Safe Community - A community where existing buildings and new construction have soil gas safe building conditions and/or on-going monitoring to prevent and/or mitigate intrusion of anthropogenic or human-made vapors.
Vapor intrusion - Vapor intrusion occurs when there is a migration of vapor-forming chemicals from any subsurface source into an overlying building. Vapor-forming chemicals may include: volatile organic compounds (VOCs), such as trichloroethylene and benzene; select semivolatile organic compounds, such as naphthalene; elemental mercury; and some polychlorinated biphenyls and pesticides.
Soil gas vapors - Soil gas is the gas underground between solid soil particles. It is above the water table and can be contaminated with volatile organic compounds (VOCs), such as dry cleaning solvents or gasoline, resulting from a chemical spill, leak or improper disposal. Naturally-occurring sources such as radon, may also contaminate soil gas. Depending upon each building's construction and ventilation, soil vapors can rise through small cracks in foundations and other openings into the building. This migration-exposure pathway is called vapor intrusion.
For the Soil Gas Safe Communities study, the indicators include differential temperature (indoor temperature minus outdoor temperature); differential pressure (indoor pressure minus outdoor pressure); and barometric pressure (indoor and outdoor). The tracer and surrogate being used is radon gas.
In the first phase of the study (method development), we are seeking approximately 30 volunteer households where Jacobs technicians will collect exterior soil gas, set up air samplers inside your home, and collect subslab samples. A signed consent (also known as an access agreement) will be solicited from the resident/homeowner before samples on the property are collected.
In the second phase of the study, we will be train volunteer community members from households to collect indoor air samples using simple equipment. We plan to host an in-person training in the community (to be determined) and will have a local point of contact to answer questions.
All community members will be informed in advance of what samples will be collected, how, where, and when. The study is voluntary, no compensation will be made to the volunteer households, and a household can withdraw from the study at any time.
During the first phase of the study (method development), contractors from Jacobs will measure for VOCs and radon gas. During the second phase of the study (community pilot), household members will use equipment to measure for temperature, pressure, and radon gas and contractors from Jacobs will stop by to download the data from the equipment.
The timeline for sample collection in your home will be communicated to you in advance. We would like to collect samples over three different seasons, such as winter, spring, and summer, to better understand the temporal variability of any vapor intrusion that may be occurring. Samples will only be collected over 1-week periods during the three seasons and the Jacobs field technician will work with you to identify good times and dates to place the air samplers in your home and collect the samples, or download the data.
During the first phase of the study, contractors from Jacobs will collect soil gas, subslab, and indoor air samples and measure for VOCs and radon gas, in addition to temperature and pressure. During the second phase of the study, residents will use provided equipment to measure for temperature, pressure, and radon.
The results will be shared after the study is completed for your community. This allows time for the samples to be analyzed in a laboratory and by our experts. We anticipate sharing results from your home in writing along with our interpretation of the results and recommended actions to take if needed.
Yes, after the study is complete, we plan to provide an explanation of the observed concentrations from the sampling events.
Yes, when we share the results for your home, we will identify your state's screening level(s) for VOCs and radon gas and will summarize recommended actions on what you can do to mitigate your exposure.
There are numerous resources available online. We recommend the following sources for more information:
- U.S. Environmental Protection Agency (EPA): https://www.epa.gov/vaporintrusion/what-vapor-intrusion#:~:text=Vapor%20intrusion%20occurs%20when%20there,with%20concerns%20over%20radon%20intrusion
- Interstate Technology Regulatory Council (ITRC): https://itrcweb.org/teams/projects/vapor-intrusion#:~:text=Vapor%20intrusion%20is%20the%20migration,elemental%20mercury%20and%20hydrogen%20sulfide
- Alaska Department of Conservation: https://dec.alaska.gov/spar/csp/sites/gaffney/ and https://dec.alaska.gov/spar/csp/vapor-intrusion/
- Your local government likely also has information specific to your state on vapor intrusion online and is a good resource to learn more about potential contamination sources near your home.
Communities
Click here for a recording of the presentation provided at the meeting:
https://soilgassafe.rti.org/Alaska re-recording.mp4
Click here to download the presentation slides:
https://soilgassafe.rti.org/WAS_soilgassafe_rti_org.pdf
Approximate location of the Gaffney West VOC Plume.
Fairbanks, Alaska
Gaffney West VOC Plume
We are currently working to develop the Soil Gas Safe Communities concept with a community and the Alaska Department of Environmental Conservation (ADEC) in Fairbanks, Alaska. The community is above the Gaffney West VOC Plume.
The contamination is believed to come from three sources associated with two historical dry cleaners and the sanitary sewer lines in the area.
Perchloroethylene or PCE, a common dry cleaning solvent, has contaminated the soil and groundwater. Contaminated plumes containing PCE and its breakdown products trichloroethylene (TCE) and dichloroethylene (DEC) have also been identified.
For more information about the Gaffney West VOC plume and past and ongoing sampling by ADEC, please visit https://dec.alaska.gov/spar/csp/sites/gaffney/.
For more information on Vapor Intrusion in Alaska, please visit https://dec.alaska.gov/spar/csp/faq/vapor-intrusion/
For more information on Radon in Alaska, please visit
https://dggs.alaska.gov/pubs/id/30163
https://dggs.alaska.gov/hazards/radon.html
Sampling Events
The EPA team are planning sampling events beginning in December 2022 and lasting until Spring 2024.
The EPA team are seeking 30 volunteer homes (specifically single-family homes and ground-floor residences of multi-unit buildings) within the areas north of Airport Way, south of 5th and 6th Ave., east of Kellum St. and west of Cushman St. to schedule a free soil gas and indoor air quality screening of their properties to assess the potential for indoor air health impacts from the existing soil vapor plume.
Between Winter 2022 - Spring 2024, we would also like to collect indoor air and subslab or soil gas samples at various times to determine if vapor intrusion is occurring at the resident's home, and how the indoor air quality varies over time. A local technician (from the firm Jacobs) will seek written consent from residents and building owners to enter the property. The technician will work with residents to identify good times to visit to place 1 sampler in the basement or crawlspace and 1 on the first floor.
The technician will return occasionally, with the resident's permission, to collect the samples during the study. Follow-up visits should last about 10 minutes.
To participate in the Fairbanks, Alaska sampling events, please contact:
Madeline Collins, Jacobs AK
Email: madeline.collins@jacobs.com
Results will be shared with building owners and residents after the study is complete.