Innovative use of a pressure‐pulse injection tool to increase transmissivity in a collection trench

Pressure‐pulse injection tools are widely used in the oil and gas extraction industry to increase well production yields; however, they have been sparingly used in the environmental industry. These injection tools work by applying a pressure pulse to the subsurface that can open subsurface pore throats in unconsolidated material, increasing yields or increasing a radius of influence from a substrate injection. Collection trenches at an industrial site were installed to increase recovery of No. 2 fuel oil in the subsurface and maintain hydraulic control of the contaminant plume. However, after operating for seven years, significant reduction in recovery was observed. Diminished recovery was attributed to biofouling, iron fouling, and/or excessive scaling. A pilot test was conducted in 2009 to determine if a pressure‐pulse injection tool could be used to inject an antifouling agent and rehabilitate two of the site collection trenches. The pilot test was successful in increasing the transmissivity of both trenches, with an order‐of‐magnitude increase in groundwater recovery at Collection Trench 1 and a 50 percent increase in recovery at Collection Trench 2. The trench rehabilitation using the pressure‐pulse injection tool was conducted at two other site collection trenches in 2010 with similar success and is now proposed as part of regular maintenance of the trenches on an as‐needed basis. © 2011 Wiley Periodicals, Inc.