Canadian Fracturing Project a Success
ARS and a Canadian bioremediation firm recently performed the first joint project at a former gas station site in northwestern Calgary, Alberta. Prior to ARS' involvement, th e Canadian firm had been successfully applying a patented bio-inoculant formula in reducing BTEX and TPH to levels below clean-up criteria to a depth of 10 ft bgs. The bio-inoculants, which include enzymes, bacteria, and nutrients, were pumped into 2-inch screened wells located throughout the site. However, soils at depths greater than 10 feet contained higher silt and clay contents that restricted the efficiency of the substrate delivery by hydraulic pumping.
In April 2002, ARS performed Pneumatic Fracturing at two separate areas of the property to increase the bulk permeability of the formation at depths greater than 10 feet bgs. Over a two-day period, five boreholes at each area were pneumatically fractured at depths from 10 to 23.5 feet bgs. Based on field data collected during the fracturing operations, including surface heave measurements and lateral pressure response in surrounding monitoring wells and boreholes, greater than 30 feet of fracturing ROI was evidenced. A total area of approximate 12,500 ft2 was enhanced by the fracturing. Through the creation of a dense fracture network in the subsurface, the permeability of the soils were increased and effective injection of the bio-inoculants in the target zone was accomplished. After fracturing, each borehole was converted to a 2-inch injection well, which was used to introduce a proprietary substrate into the fractured zones by hydraulic pumping. Post-fracture injections performed in all ten wells indicated that injection rates increased by an average factor of five. During the first injection application (May, 2002), 30,000 U.S. gallons were introduced into the subsurface. Post-injection sampling is scheduled to occur mid-summer. Further project results will be reported in future newsletters.
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