NC001 – Pneumatic Fracturing
Manufacturing Facility, North Carolina
Figure 1: Site Layout (inside)
Pneumatic Fracturing (PF) proves to be the best option when remediating a manufacturing facility without interrupting daily plant activities.
In November, 2001, a three-day field application at a manufacturing facility in North Carolina was completed. Pneumatic Fracturing was applied in four (4) boreholes targeting discrete intervals from 6-27 ft. below ground surface. The goal of this project was to increase flow rates in the low permeable saprolitic formation that has been contaminated with Trichloroethene (TCE).
This project was challenged by the presence of a load-bearing wall, located within 6 and 25 ft. of a pair of injection locations. Extensive survey of the walls and computer modeling were performed on the load-bearing structure to determine its allowable movement and ensure that no detrimental impact would occur from the fracturing. The load-bearing columns were monitored closely during all fracturing events to ensure that heave did not exceed the movement criteria, as determined from the computer modeling.
Figure 2: Map of Site Layout
Using pressures less than 150 psi, the formation was fractured. Pressure response measured in surrounding monitoring wells using pressure gauges supported a fracturing radius of influence of 25+ ft. Extraction and air sparging tests performed by the client subsequent to the completion of Pneumatic Fracturing indicated very promising results. Figure 1 shows results of the post fracture SVE tests.
Based upon the success of the overburden saprolite work, ARS was contracted to fracture the mudstone or tuff bedrock formation. Using a single open rock well, a zone from 27.5–45 ft. bgs was fractured. Based upon pressure response at surrounding monitoring wells, pressure-history curves and ground surface heave, an expanded fracture network was created. An estimated 17 ft. fracture radius was achieved.