A Natural Cleanup

by Christopher H. Nelson, Bioremediation Technology Manager; Groundwater Technology, Inc., Englewood, CO,

Serial Information: Civil Engineering—ASCE, 1993, Vol. 63, Issue 3, Pg. 57-59

Document Type: Feature article


For almost 30 years, nonvolatile petroleum hydrocarbons from used motor oil, diesel, gasoline and other automotive fluids had been released to an oil sum at a truck-maintenance facility in Denver. The site had both vadose—and saturated—zone contamination. The facility's owner, Public Service Company of Colorado, hired Groundwater Technology Inc., Englewood, Colo. to complete a site assessment and to initiate and design the on-site remediation system, one that would not disrupt ongoing maintenance and building expansion. After reviewing several remedial options, we selected in situ bioremediation. With such a system, the indigenous microbial populations are stimulated to degrade the contaminants. The method converts organic wastes into biomass and harmless by-products of metabolism such as carbon dioxide, water and inorganic salts. Within saturated environments, ground water is usually recovered, amended with nutrients and reinfiltrated. Oxygen is added by either injecting hydrogen peroxide (which decomposes to oxygen and water) or installing an air-sparging system. For vadose zone contamination, nutrients are added through percolation or injection. Oxygen is normally supplied through a negative pressure vapor extraction system.

Subject Headings: Non-renewable energy | Petroleum | Pollution | Groundwater | Building design | Salt water | Nutrients | Hydrocarbons | Colorado | United States | Denver

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