LBG Receives AAEE Grand Award03/02/2006
ST. PAUL, MN — Leggette, Brashears & Graham, Inc. (LBG), a professional groundwater and environmental engineering services firm, DaimlerChrysler have been awarded the Grand Prize for Small Projects from the American Academy for Environmental Engineers (AAEE), as part of the organization’s 2006 Environmental Excellence Awards competition.
LBG and DaimlerChrysler were cited for development of an innovative remediation technology that successfully cleaned up toluene contaminated groundwater at a former facility owned by DaimlerChrysler Corporation in central Michigan.
The initial contaminated area at the site, resulting from a toluene release, was successfully cleaned up in the late 1990’s using an air-sparge/soil vapor extraction technology. Subsequent testing revealed that a residual pocket of toluene remained in a difficult to reach area beneath an electrical substation and a large fire-protection water tank, an area also criss-crossed by utility lines. The limited access, complicated by a short amount of time to execute the cleanup, required an innovative approach. Standard remedial technologies were considered, but none could meet the site objectives.
Borrowing from technologies in a wide array of engineering fields, LBG and DaimlerChrysler developed a new remedial technology that had not been applied to the field of environmental clean-ups. Starting with a gas/liquid contracting process commonly used in chemical engineering, a process was created that increases the dissolved oxygen concentration of municipal water from 5 up to 40 mg/l by contacting the water with oxygen in a high efficiency plunging liquid jet gas/liquid contactor.
The super-oxygenated municipal water was injected under city water pressure into the aquifer to deliver large quantities of dissolved oxygen to the impacted areas. Because the oxygen traveled with the groundwater in a dissolved phase, the remedial radius of influence was much larger than other injection techniques, allowing the remediation to take place under difficult to reach areas beneath the electrical substation and the water tank.
The system was anticipated to run for a minimum of two years, but had fully remediated the site – to levels too low to be detected – within 16 months. This remediation timeline is impressive, considering that more traditional remediation technologies would have taken anywhere from two to twenty years to achieve similar results.