UNITED-STATES-ENVIRONMENTAL-PROTECTION-AGENCY SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION OF PNEUMATIC FRACTURING EXTRACTION (SM)

The U.S. Environmental Protection Agency (EPA), in cooperation with Ac cutech Remedial Systems (ARS) and the New Jersey Institute of Technolo gy (NJIT), performed a field demonstration of Pneumatic Fracturing Ext raction (PFE)SM for the removal of chlorinated-volatile organic compou nds (VOCs) from vadose zones of low permeability. The demonstration wa s conducted in the fall of 1992 at an industrial park in Somerville, N ew Jersey, where removal of VOC contamination in shale bedrock was req uired to comply with New Jersey's Environmental Cleanup Responsibility Act (ECRA). During the demonstration, airflow and contaminant concent rations were monitored to establish a database against which the devel oper's claims about the technology were evaluated. The developer conte nded that PFE would increase extracted-airflow rates from the subsurfa ce formation by at least 100 percent and would increase the mass remov al rate for the key contaminant, trichloroethene (TCE), by at least 50 percent. Also, during the demonstration hot-gas injection was evaluat ed. Based on comparisons of four-hour test results before and after fr acturing, airflow rates increased more than 600 percent, and TCE mass- removal rates increased about 675 percent. The increase in TCE mass-re moval rates appeared to be a result, primarily, of the increased airfl ow. In addition, the extracted air contained significantly higher conc entrations of other VOCs after fracturing. Using data developed in the four-hour postfracture test, the estimated cost for a hypothetical on e-year clean-up is $140 per pound of TCE removed, or $140 per ton of s oil contaminated with one pound of TCE. Experiments to evaluate the ef fects of injecting heated air, at 200 to 250-degrees-F, into the vados e zone gave inconclusive results.