John R. Schuring

Application of Pneumatic Fracturing to Enhance In Situ Bioremediation

A field pilot demonstration integrating pneumatic fracturing and in situ bioremediation was carried out in a gasoline-contaminated, low permeability soil formation. A pneumatic fracturing system was used to enhance subsurface air flow and transport rates, as well as to deliver soil amendments directly to the indigenous microbial populations. An in situ bioremediation zone was established and operated for a period of 50 weeks, which included periodic subsurface injections of phosphate, nitrate, and ammonium salts. Off-gas data indicated the formation of a series of aerobic, denitrifying, and methanogenic microbial degradation zones. Based on soil samples recovered from the site, 79% of soil-phase benzene, toluene, and xylenes (BTX) was removed by the integrated technology. From mass balance calculations, accounting for all physical losses, it was estimated that 85% of the total mass of BTX removed (based on mean concentration levels) was attributable to biodegradation.

Using pneumatic fracturing for in‐situ remediation of contaminated sites

Pneumatic fracturing is an innovative technology enhancing the removal and treatment of contaminants in moderate-to-low permeability formations. The main advantages are a reduction in treatment time and the extension of available in-situ technologies to more difficult geologic conditions. Pneumatic fracturing has been successfully demonstrated in the field at a number of contaminated sites and in a variety of geologic formations. The technology is now commercially available and is being incorporated into site cleanups. This article provides an overview of the pneumatic fracturing technology, beginning with a general description of the concept and apparatus. Next, key technological considerations will be discussed including fracture initiation, fracture orientation, fracture flow, and treatable soils and contaminants. Three case studies are presented describing different applications of pneumatic fracturing. The article concludes with a discussion of cost benefits of the technology.

Radon contamination in dwellings

Radon contamination of dwellings has only recently been recognized as a significant problem in the United States. This paper describes the geographical distribution of radon gas, along with a discussion of its fundamental health effects. Various methods to measure radon and radon daughter concentration levels are presented. Recommended action levels for radon gas exposure in dwellings are summarized, and factors which influence measured radon concentrations are discussed.