During a recent project through Western Technologies’ environmental group, Mother Nature showed up with her holistic and organic cleaning powers. Western Technologies (WT) was managing a remediation project for a gasoline release on a site located in Arizona. The site also contained a plume of free product waste oil and an abandoned old septic system.
Since it was not a threat to human health or the environment, WT’s goal for the waste oil was to eliminate the free product to reduce its mobility. This was accomplished by bailing the well until no more free waste oil liquid was left. The residual waste oil was considered merely a nuisance and was not targeted for further remediation.
To remediate the gasoline in groundwater, air sparge wells were installed to inject compressed air beneath the water table. The rising bubbles strip volatile organic compounds (VOCs) from the water and soil below the water table. However, since waste oil does not evaporate, this process would not work for the residual waste oil.
To remediate soil above the groundwater table, soil vapor extraction wells were installed to pull air out of the soil above the water table. Vapor extraction creates negative pressure in the soil to increase the flow of air through the soil. It captures and burns off the VOC’s with a catalytic converter.
During the push and pull process of air through the soil, a welcomed thing happened with the waste oil.The oxygenation stimulated bioremediation and completely eliminated the waste oil residue in the soil and groundwater. The before and after photographs of bailed water from the waste oil contaminated well were taken about 10 months apart. WT believes the reason this dramatic change occurred was related to the biological wee-beasties and nutrients that were made available by the abandoned septic system. So, in addition to cleaning up the gasoline and the waste oil, the nutrient load from the malfunctioning septic in the area was also reduced.
Now that’s “killing three birds with one stone”! Rock on Mother Nature!
