CB and I Federal Services Lawrenceville United States
This ESTCP demonstration evaluated the technical effectiveness and cost of in situ propane biosparging for treating N-nitrosoclimethylamine NDMA in groundwater. The demonstration site was the Aerojet Superfund Site in Rancho Cordova, CA. The propane sparging system, which consisted of three biosparging wells connected to an air compressor and propane gas feed, supplied approximately 1.8 lbs of propane to the in situ test plot per day to stimulate native bacteria to biodegrade NDMA. Over the 374 day operational period of the system, NDMA concentrations were reduced by 99. 7 in the treatment area, declining from as high as 25,000 ngL to 3 ngL in one system monitoring well. Over the same time period, NDMA concentrations in a side gradient control well declined by only 14 . There were no negative impacts to groundwater geochemistry. A full-scale biosparging system was determined to be approximately 40 less expensive to build, install, and operate than a comparable ultraviolet system over a 30 year remedial time frame.