The geology at the site consists of overburden soil overlying the Passaic Formation, a sedimentary rock made up of interbedded sandstone, siltstone, shale, and conglomerate. Poorly sorted sands with some gravel and occasional silt and clay beds characterize the overburden. The upper portion of the Passaic Formation is highly weathered and fractured.
Targeted Environmental Media:
 Dense Non-aqueous Phase Liquids (DNAPLs) - Fractured Bedrock
Major Contaminants and Maximum Concentrations:
- Copper chloride (0 µg/L)
- Nitrobenzene (100,000 µg/L)
- Aniline (25,000 µg/L)
- Vertical Chemical Profiling
- Packer Isolation
- Cluster Wells
- Multi-sampling port
- Pumping Tests
- Bioremediation (In Situ)
Comments:
The basis of design of the in situ bioremediation system was a field trial conducted between March and August 2002. Low-flow pulsed injection of oxygen gas was performed for 64 days, during which time 4,200 pounds of oxygen were injected into the overburden and weathered bedrock via four injection wells.
The in situ bioremediation system is being implemented full scale in a phased approach, with the Phase I acting as an extended pilot test. The Phase I in situ bioremediation system consists of an array of 32 oxygen injection wells in the overburden and weathered bedrock spaced 40 to 80 feet apart in an area 160 feet wide by 400 feet long. Phase I began operation in December 2003. The oxygen supply system is composed of a 3,000-gallon liquid oxygen storage tank and evaporator and a fully automated oxygen distribution system housed in a portable trailer. Oxygen gas is pulse injected in 2-minute intervals every half-hour.
Source reduction, numerical cleanup goals have not been established.
During the pilot study, rapid dispersion of dissolved oxygen was observed in groundwater, and semivolatile organic compound (SVOC) concentrations were reduced by more than 90 percent within 5 weeks. First-order biodegradation rates for aniline and nitrobenzene were calculated to be less than 10 days (expressed as a half-life).
Results of the Phase I in situ bioremediation system are available from the authors.
Reference:
Sperry, Kenneth L.; Omer J. Uppal; Dennis Keane; Matthew Nelson; Jaydeep Parikh; John L. Persico; Joseph J. Tota. 2005. Aerobic in-situ bioremediation of semi-volatile organic compounds via an oxygen gas injection system. The Eighth International In Situ and On-Site Bioremediation Symposium, Baltimore, Maryland. June 6-9.
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