3 Million Gallon Fuel Release: Mandan, North Dakota
An estimated 3 million gallons of diesel fuel was suspected to have been released from transmission lines associated with a rail yard into the subsurface beneath a police station and adjacent downtown business district. Subsequent site investigations revealed diesel impacts over a four-block area, including indoor air impacts identified at the police station and several other businesses.
Prior to project involvement by Leggette, Brashears & Graham, Inc. (LBG), remedial progress had been slow and relatively ineffective. The slow pace depressed the downtown economy (the result of a lack of real-estate investment brought on by the diesel contamination), which prompted the City and state agency to resolve the diesel contamination problem. In less than three days, LBG prepared a proposal to remove the diesel product, which was quickly accepted.
SCOPE OF WORK
Within 1½ years, LBG designed, installed, and started one of the largest remediation systems in the State. The work included conducting indoor air assessments and implementing engineering controls to minimize vapor intrusion where required; design coordination; securing access; maintaining public relations; construction and installation of remediation wells, numerous multi-phase extraction and soil vapor extraction systems, water and air treatment systems, and an integrated control system; and conducting start-up activities. All of the work was conducted within a busy downtown area.
To prevent disruptions to businesses, LBG implemented creative designs, and utilized state-of-the-art installation technologies. As a result, system installation proceeded with little disruption to business, and with no complaints. To jump-start the downtown economy, LBG partnered with a real-estate developer and successfully introduced new state legislation to protect investors from liability when purchasing the impacted properties. With the removal of the liability comes a responsibility to protect human health, so local ordinances were passed requiring engineering controls on all new construction to prevent any exposure from the existing contamination.
Within two years of start-up, more than 500,000 pounds of hydrocarbons have been removed, primarily diesel, but also gasoline, solvents, and methane.