Workshop TA1.

Understanding Vapour Intrusion pathway

Thursday, 12 September, 2019

Presenters: Dr. Atul Salhotra


Vapour intrusion (VI) exposure pathway is potentially complete at all sites where groundwater and/or soils impacted by volatile and semi volatile chemicals such as petroleum hydrocarbons and chlorinated solvents. Over the past several years, VI has gained significant attention among the environmental and construction industry. Therefore it is critical that the potential exposure and risk be accurately quantified and appropriate mitigation measures be implemented if the risk exceed the acceptable levels. This course will present (i) development of a site conceptual model for VI, (ii) best-practice planning for site investigation, collecting the right quality and quantity of data to screen the sites and quantify risk accurately, (iii) calculation of risk due to VI and (iv) mitigation of VI if required.

Who should attend?

The workshop will be useful for all stakeholders involved in the assessment and mitigation of risk due to indoor VI. These include regulators, responsible parties, and service providers. No previous background in risk assessment or indoor VI is required. Geologists, engineers and environmental professions with a variety of educational backgrounds will benefit from this course.

Detailed Course Outline & Schedule 






  • Introduction of the trainers and attendees


Dr. Atul Salhotra

1:35 pm

Conceptual model for vapour intrusion pathway

  • Volatilisation of chemicals from soils and groundwater
  • Migration of chemicals in vadose zone
  • Intrusion into buildings
  • Mixing with Indoor air
  • Estimation of exposure to building occupants
  • Methods to evaluate the pathway



Dr. Atul Salhotra


Site Investigations to collect the right quality & quantity of Data for VI evaluation

  • Soil gas and subslab sampling
  • Indoor air and ambient air  data
  • Evaluation of multiple-line-of –evidence approach for VI investigations

Receptor specific data


Dr. Dawit Bekele


Afternoon tea



Application of Data to Estimate Risk

  • Models for vapour migration
  • HHRA from soil/GW concentration
  • Use of soil gas data in HHRA
  • Modeling & Empirical attenuation factor



Dr. Renato Baciocchi

Dr. Iason Verginelli



Strategies to Mitigate Vapour Intrusion

  • Source control
  • Vapour barriers
  • Enhanced ventilation

Dr. Atul Salhotra