Indoor Vapor Intrusion – Chemical – Commercial

Indoor Vapor Intrusion – Chemical

What You Need to Know

Vapor intrusion is the process by which chemicals in soil or groundwater migrate to indoor air above or near (within a 100’ or even greater) a contaminated site

Adverse health effects based upon length, amount, frequency or exposure as well as toxicity of chemical and sensitivity of affected parties

Entrance occurs thru building cracks and closed, tight buildings increase effects

Most reliable sampling methodology-soil gas samples under building foundation

Common sources- gas stations, dry cleaners, body shops, metal works, landfills, industrial sites,etc.

What You Need to Do

Review the most current EPA technical guidelines, ASTM, ITRC (Interstate Technology & Regulatory Council) guidelines and any state requirements for vapor intrusion

Consider all potential vapor intrusion pathways as per technical guidelines

Mitigation can consist of active soil depressurization, passive soil ventilation, positive indoor pressurization, increasing indoor ventilation, sealing cracks/openings in foundation, and installing passive barriers

Operations and maintenance of vapor intrusion mitigation systems usually entail periodic follow up inspections (yearly) with the state and EPA also performing validation inspections

Myths and Misconceptions

If I had a Phase 1 Environmental Site Assessment (ESA) performed several years ago, I do not have to worry about a vapor intrusion issue-FALSE

As long as there are no discernible odors on the property, there can be no vapor intrusion-FALSE

We have a No Further Action (NFA) letter on our site and the site has been closed, therefore vapor intrusion cannot be an issue-FALSE

Indoor air sampling for vapor intrusion can be problematic and must be carefully evaluated or results may indicate false positives/negatives-TRUE