Engineering reliability assessment of contaminant removal by pneumatic fracturing

Pneumatic fracturing is a new enhancement process that has been accepted and recognized as a cost-effective technology in removing contaminants from polluted sites. This paper presents an engineering reliability assessment method for mass removal by the pneumatic fracturing process. An analysis was performed of mass removal with respect to four controlling input parameters, including diffusion coefficient, retardation factor, fracture aperture, and flow rate, each of which is stochastic in nature. The reliability index ratios were found to be greater than unity for each input parameter. From a site-remediation standpoint, the analysis reveals the physical significance of the four parameters in the pneumatic fracturing process. The tortuosity and retardation factor probability distributions have important impacts on the mass removal rate. The dimension of fracture aperture shows a limited direct influence on the mass removal with an independent flow rate input. Mass removal is sensitive to flow rate for relatively low flow range. The method described herein is a first attempt in reliability assessment of contaminant removal by pneumatic fracturing. Its approach can be further applied to other remediation operations.