Suzi Rosen, Partner Engineering & Science
Phase II Environmental Site Assessment (ESA) activities for a light industrial building in Los Angeles, California identified volatile organic compounds (VOCs) in the subsurface at levels that indicated a potential indoor air quality (IAQ) concern related to vapor intrusion of VOCs. The application of a floor coating material was part of the building renovation activities. Photoionization detector (PID) measurements were used as a field screening tool prior to, during, and after the application. Extensive preparatory activities were required to condition the floor prior to the application. IAQ sampling was performed two weeks following application, with all samples locations except for one being reduced to below residential screening levels. Engineering controls consisting of modification of the HVAC system were then implemented and a third sampling event showed reduction of VOCs at all sample locations to concentrations below residential screening levels. Although the mitigation approach successfully reduced indoor air VOC concentrations to acceptable levels, there were many challenges and lessons learned throughout the project that caused or had potential to cause significant delay in implementation time.