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Soil Vapor

Soil Vapor and Soil Gas Testing

Vapor intrusion, when volatile chemicals from contaminated soil or groundwater migrate into indoor air, poses significant health and regulatory risks. Accurate soil vapor or soil gas sampling is essential to assess exposure, design mitigation strategies, and demonstrate compliance with agency requirements.

Soil gas and sub-slab monitoring can be an important component of site assessments, or contaminated sites remediation especially if the site is known to contain volatile hydrocarbons such as a fuel spill site or was affected by the use of chlorinated solvents such as dry-cleaning sites.

Vapor intrusion services from a leading provider of testing and monitoring solutions 

We offer an unrivaled combination of vapor intrusion delineation tools, sampling equipment, and analytical capabilities that will enable you to meet project and regulatory targets. Our vapor intrusion specialists are ready to help you to develop a site specific and cost effective sampling plan that takes you from site characterization to site closure. 

In the US, vapor intrusion studies are required under many programs, for example, under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) or Superfund, which provides technical guides to assessing and mitigating vapor intrusion pathways. Vapor intrusion studies can also arise from site assessments and due diligence depending on what was identified in a Phase I ESA.

In Canada, vapor intrusion guidelines and best practices are provided at the federal level, the CCME guidelines for example, and at the provincial level, Ontario’s draft vapor intrusion guidance for example.

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Vapor Intrusion Characterization and Monitoring

Fully characterize and monitor your site with the help of our state-of-the-art delineation tools and regulatory compliant analytical capabilities

Potentially toxic and carcinogenic vapors can accumulate in indoor air in buildings near or on top of a contaminated site. These substances, which can include chlorinated volatile organic compounds [CVOCs], petroleum products and polycyclic aromatic hydrocarbons [PAHs], pose risks to human health through inhalation. Vapor intrusion monitoring and characterization is essential for preventing such health risks and ensuring compliance with regulations. 

Vapor Intrusion Calculator

Why choose vapor intrusion characterization and monitoring from SGS? 

Testing for vapor intrusion is complicated by temporal and spatial variability. This means that a multiple lines of evidence (MLE) approach is needed to properly interpret results and make decisions. 

Our direct read instruments, variety of sampling equipment and analytical capabilities will help you to complete an MLE investigation from site characterization to site closeout. 

Delineation Tools 

  • Passive assay badges 
  • SmartSense 
  • AIHR Shark 
  • Field meters
    • MiniRae
    • MultiRae
    • Multi-gas meter

Sample Analysis
(by media): 

  •  Indoor air 
  •  Outdoor
  •  Ambient air 
  •  Soil vapor 
  •  Sewer vapor 
  •  VIMS exhaust

Sample Analysis
(by method): 

  •  TO-03 
  •  TO-04 
  •  TO-13 
  •  TO-15 
  •  TO-17
  •  ASTM 1946 
  •  Specialty metals

Equipment Rentals: 

  •  Sampling canisters 
  •  Flow controllers 
  •  TEDLAR bags 
  •  Digital pressure gauges 
  •  Soil gas sampling manifolds 
  •  Air sampling pump rentals 
  •  Field meters 
  •  Passive assay badges 
  •  SmartSense 
  •  AIHR Shark 

Indicators, Tracers, and Surrogates (ITS): 

  • Helium detector 
  •  Continuous monitoring sensors:
    • Temperature, Pressure & Humidity
    • Total volatile organic compounds (VOCs) 

SGS Vapor Intrusion Calculator


Note: This calculation was derived from the ideal gas law and assumes a standard temperature and pressure of 25°C and 1 atm.

Please use the following references for more information about calculations. If calculations are needed for other scenarios (i.e. temperature, pressure, or analytes) contact us.

  1. EPA Indoor Air Unit Conversion
  2. EPA Indoor Air Unit Conversion Examples (PDF)
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SGS Methods

The most common analytical method used for vapor intrusion testing, whether it is soil gas or sub-slab probes testing is TO-15 (currently version TO-15A). This method measures 82 VOCs collected in stainless steel canisters by GC-MS. TO-15A is a sensitive method that can measure VOCs in the pptv-ppbv range depending on the analyte and can be extended to compatible analytes with the appropriate validation and accreditation.

While TO-15 has been successfully implemented by many commercial laboratories, sustained success requires a lot of attention to detail

  • Consistent canister cleaning to avoid contamination
  • Quality checked fittings to avoid leaks during sampling and transport
  • Well calibrated flow controllers to ensure accurate flow rates
  • Clear understanding of project goals to set the appropriate flow rates, sampling times and capture setup
  • A good inventory of canisters, flow controllers and other supplies backed by a robust batch or individual canister QC program as appropriate
  • Experienced lab analysts to ensure accurate and precise lab data. Method success requires avoiding contamination, setting up the pre-concentrator correctly and ensuring the GC-MS is properly optimized, tuned and operated
  • A well-established QA program that is attuned to the specific needs of air testing

The SGS Soil Gas Analysis Advantage

  • Experienced laboratories with multiple locations in US and Canada
  • Extensive accreditation for multiple labs with overlap on
    • > 100 parameters extending TO-15A to compatible analytes
    • Multiple accreditation frameworks including NELAP, DoD QSM and ISO-17025
    • Capabilities for ultra-low TO-15 selective ion mode (SIM) lower reporting limits if needed
  • A thorough QA/QC program with standardized cleaning procedures, flow controller calibration and batch or individual canister checks as specified by the project plan
  • An experienced air analysis team

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