Paul Nicholson, P.Eng.

Paul is a Principal Engineer based in Ontario with more than 18 years of experience in environmental consultation with a focus on assessment and mitigation related to human health risks associated with sub-surface vapour intrusion (VI).

As a senior member of Geosyntec’s VI practice, Paul works with clients to incorporate sampling and investigation tools that support the development of conceptual site models (CSMs) which enable clients to make definitive decisions on the VI pathway. He also helps clients with innovative technologies such as high-volume sampling, pressure control, mass flux assessment, and passive sampling to evaluate and mitigate VI at both residential and commercial properties. He has worked across several jurisdictions in North America, Southeast Asia, and Oceania, and was seconded to Geosyntec’s Malaysia office from 2010 to 2011 and the Melbourne Australia office from 2016 to 2018.

Paul was integrally involved in the development of Geosyntec’s High Volume Sampling (HVS) protocols and associated models to enhance the characterization and understanding of sub slab vapour variability. He was also the project manager for a United States Department of Defense Environmental Security Technology Certification Program (ESTCP) validation and demonstration program which involved high-volume sampling for vapour mitigation system optimization.

Paul continues to advance the investigation of the VI pathway through the development of innovative techniques such as pressure control and passive samplers. In addition, he has specific experience in the development, oversight, and management of large VI investigations at petroleum hydrocarbon and chlorinated solvent sites. This includes the development of many large scale VI assessment programs for properties with as many as 1,000 buildings and the prioritization of properties based on a specific conceptual site model using historical soil and groundwater information. Paul has designed both retrofit and new build VI mitigation systems for chlorinated solvents, petroleum hydrocarbons, methane, and radon. In addition, he has experience with in-situ remediation technologies which include enhanced in-situ bioremediation (EISB), soil vapour extraction (SVE), multi-phase extraction (MPE), and soil venting technologies.


Vapour Intrusion Investigation, Vapour Intrusion Mitigation System Design, and Enhanced In-Situ Bioremediation

Practice Areas

Contaminated Site Assessment and Cleanup


Environmental Engineering; Water Resources; Environmental, Health, and Safety


B.A.Sc., Environmental Engineering – Chemical Specialization, University of Waterloo, 2004


Ontario Professional Engineer, License No. 10012745