Overview:
The Nebraska Department of Environmental Quality (NDEQ) began considering an enhanced in situ bioremediation pilot study at the Ogallala Groundwater Contamination site in 1998. The project commenced after ITRC provided NDEQ staff with training, documents, and networking opportunities regarding in situ bioremediation. The pilot study was designed to demonstrate the application of the enhanced anaerobic degradation process at this site contaminated by chlorinated solvents. Though the study is ongoing, initial indications are positive; they show that this technology can be used to remediate this site as well as other chlorinated solvent sites in Nebraska. In addition, NDEQ and Region VII EPA took this opportunity to study enhanced reductive dechlorination treatability on a portion of the PCE (tetrachloroethlylene) groundwater plume. The implementation of the Ogallala pilot study is already prompting enhanced in situ bioremediation to be considered for other sites in Nebraska. The momentum is also building for additional applications of this technology. The following provides background information about the Ogallala project as well as about the current status and anticipated actions.

Background:
A treatability study was performed at the Ogallala Groundwater Contamination Site to determine whether PCE could be reductively dechlorinated in the shallow alluvial aquifer. An in situ treatment cell was developed in a portion of the PCE plume at a downgradient from the dry cleaners. A substrate solution consisting of 60% food grade sodium lactate was injected at intervals of 3 to 4 weeks to allow for adequate mixing and dispersal. Geochemical changes in the groundwater were monitored to assess the REDOX conditions and to ascertain the best injection schedule. Conditions in the groundwater plume were reduced in a step-wise fashion: first was denitrification, followed by reduced iron and manganese, and finally by reduced sulfate. (Murt et al., 2000). Fermentation of the lactate was confirmed by the presence of volatile acids under methanogenic conditions and an increase in carbonate. Reducing conditions and microbial fermentation of the lactate indicate that geochemical conditions are appropriate for the reductive dechlorination process. Ground water analyses performed during March and April indicate that PCE is being reductively dechlorinated. The concentration of PCE was significantly lower at the downgradient end of the test cell in addition to the detection of both TCE and cis-1,2-DCE. Vinyl chloride has not been detected to date, which may be the result of the low concentrations of cis-1,2-DCE or the rate of ground water flow at the test site area in relation to the size of the cell.

ITRC Involvement:
In September 1997, two members of NDEQ staff and management attended the first ITRC Natural Attenuation course, held in Austin, Texas. The training class served as a catalyst for the enhanced in situ bioremediation project. Of the training introduction, Victoria Murt, NDEQ Ogallala Project Manager, said: "The book [training manual] and the class [ITRC Natural Attenuation Training] provided a more clear understanding of the various bioremediation mechanisms and the necessary geochemical and food/nutrient requirements. Of particular help were the one-on-one discussions that I had with various trainers regarding studies that were currently underway." The professional relationships she and others gained through the ITRC network are fostering acceptance of innovative technologies in Nebraska.

Benefits: Nebraska is benefiting from its participation in ITRC by planning for future cleanup efforts. Initial information from the pilot study has prompted this technology to be considered for other operable units at the Ogallala site as well as for other sites in Nebraska. If this enhanced in situ bioremediation technology is implemented as the primary technique, over a more traditional pump and treat scenario at the Ogallala site, the overall cost savings has been estimated at 50% to 75% over that for the more traditional technology.

The confidence level and willingness of NDEQ staff and management to evaluate and use new environmental technologies is a direct result of their ITRC participation. NDEQ project managers have benefited from the network of others across the nation-including state regulators and industry experts who serve as resources for this project. In addition, the EPA Region VII project manager for Ogallala has taken the same ITRC training in natural attenuation and has access to the same ITRC technical and regulatory documents (Natural of Chlorinated Solvents in Groundwater: Principles and Practices and Technical and Regulatory Requirements for Enhanced In Situ Bioremediation of Chlorinated Solvents in Groundwater). This shared training and information has led to greater cooperation on this EPA-led and state cost-share site.

Through the ITRC, NDEQ personnel can develop professionally while making great strides in cleaning up some of Nebraska's most significant hazardous waste sites. In May 2000, Victoria Murt will be presenting the results of the pilot study at the internationally renowned bioremediation conference sponsored by Batelle in Monterey, California. In the draft document written by Ms. Murt and her colleagues, the ITRC document entitled Technical and Regulatory Requirements for Enhanced In Situ Bioremediation of Chlorinated Solvents is a primary reference.

Who to Contact for Additional Information:
Victoria Murt
Nebraska Department of Environmental Quality
Suite 400, The Atrium
1200 N Street
Lincoln, NE 68509-8922
P: (402) 471-6411
F: (402) 471-2909
deq115@mail.deq.state.ne.us

Reference:
Murt, V. (NDEQ), Huscher, T. (NDEQ), and Easley, D. (Region VII EPA), A Reductive Dechlorination Treatability Study of a Shallow Alluvial Aquifer, March 2000 draft, in preparation for the Batelle Bioremediation Conference, May 2000.

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