CA002 – Pneumatic Fracturing
Industrial Facility Northwestern California
Pneumatic Fracturing (PF) was applied at a rail yard site located adjacent to a 150 year-old historical building in Northern California where contaminants such as VOCs, polynuclear aromatic hydrocarbons and metals had been detected in the soil and groundwater. The contamination stemmed from historic onsite activities. To address the presence of VOCs in the subsurface, an SVE/CatOx system was installed. Although a significant amount of VOCs had been removed from the upper sand layer, the presence of these contaminants was still detected in the clay layer. As a result, Pneumatic Fracturing was applied in order to increase the permeability in the clay zone.
The process required the application of Pneumatic Fracturing to address a discrete clay layer (16-20 ft. bgs) within the formation. The unique challenge of this project was the application of the technology without damaging the historical building.
After Pneumatic Fracturing, concentrations in the extraction gas increased significantly and vacuum influence was extended to wells previously not influenced. The fracturing activities did not impact the structural integrity of the historic building only 20 ft. from the injection points.
Figure 1: On the left–ARS surveying pre-existing cracks and blemishes on building before injection. On the right–The white chalk marks show grid system use in documentation pre-existing condition of structure.