Numerical study of building pressure cycling to generate sub-foundation aerobic barrier for mitigating petroleum vapor intrusion.

In this study, the role of building pressure cycling (BPC) method in generating a subslab aerobic barrier at petroleum contaminated sites was examined numerically. The numerical model was first validated with field observations and then used to simulate BPC applications in petroleum vapor intrusion scenarios. The results indicated that, after a long-term BPC operation (60 days), a subslab aerobic barrier could be generated with an adequate air injection rate (10 L/min in this study). The effects on hydrocarbon soil gas concentration profiles are expected to last for weeks even after the BPC system is turned off. Moreover, our investigations showed that the performances of the BPC application are virtually independent of hydrocarbon's reaction rate constant. The simulated sub-foundation aerobic conditions expected during BPC were comparable to those observed in a field study where a subsurface pipe system at the same air injection rate was used to create a subslab aerobic barrier. Thus, BPC application can represent an interesting alternative approach to the subsurface delivery systems as it is expected to achieve similar performance but with lower installation costs.