This paper describes the results of the first field-scale demonstration conducted to evaluate the performance of nanoscale emulsified zero-valent iron (EZVI) injected into the saturated zone to enhance in situ dehalogenation of dense, nonaqueous phase liquids (DNAPLs) containing trichloroethene (TCE). EZVI is an innovative and emerging remediation technology. EZVI is a surfactant-stabilized, biodegradable emulsion that forms emulsion droplets consisting of an oil−liquid membrane surrounding zero-valent iron (ZVI) particles in water. EZVI was injected over a five day period into eight wells in a demonstration test area within a larger DNAPL source area at NASA's Launch Complex 34 (LC34) using a pressure pulse injection method. Soil and groundwater samples were collected before and after treatment and analyzed for volatile organic compounds (VOCs) to evaluate the changes in VOC mass, concentration and mass flux. Significant reductions in TCE soil concentrations (>80%) were observed at four of the six soil sampling locations within 90 days of EZVI injection. Somewhat lower reductions were observed at the other two soil sampling locations where visual observations suggest that most of the EZVI migrated up above the target treatment depth. Significant reductions in TCE groundwater concentrations (57 to 100%) were observed at all depths targeted with EZVI. Groundwater samples from the treatment area also showed significant increases in the concentrations of cis-1,2-dichloroethene (cDCE), vinyl chloride (VC) and ethene. The decrease in concentrations of TCE in soil and groundwater samples following treatment with EZVI is believed to be due to abiotic degradation associated with the ZVI as well as biodegradation enhanced by the presence of the oil and surfactant in the EZVI emulsion.

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information, it if does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITORS ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTThis cost and performance report is a compilation of technical and performance data from three recent Navy demonstration projects involving the use of microscale or nanoscale zero-valent iron (NZVI) for treatment of dense, nonaqueous-phase liquid (DNAPL) source zones. SUBJECT TERMS EXECUTIVE SUMMARYZero-valent iron (ZVI) has been used in permeable reactive barriers for groundwater treatment for over ten years now. ZVI or elemental iron (Fe 0 ) is a strong reducing agent that is capable of abiotically dehalogenating several common chlorinated solvents (e.g., trichloroethene [TCE]), which are common pollutants at military and industrial sites. The granular ZVI used in permeable barrier applications typically consists of iron particles in the size range of −8+50 mesh, which makes the ZVI barrier more permeable than the surrounding aquifer. An emerging technology based on ZVI is the use of nanoscale zero-valent iron (NZVI) for source zone, rather than plume, treatment. In source areas, solvent may be present as dense nonaqueous-phase liquid (DNAPL) or free-phase solvent and dissolved-phase concentrations in the region tend to be much higher than in the downgradient plume. The finer NZVI particles are much more reactive than granular ZVI and have the potential to quickly treat the higher concentrations of chlorinated volatile organic compounds (CVOC) present in source zones. Also, finer particles are easier to inject in the soil pores than coarse particles, so the smaller particle size of NZVI helps its delivery.The Navy has recently conducted NZVI field demonstrations at three sites: Hunters Point Shipyard (Hunters Point), Naval Air Station (NAS) Jacksonville, and Naval Air Engineering Station (NAES) Lakehurst. This cost and performance (C&P) report is the result of a comparative evaluation of the performance of N...

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The ability of bioremediation to treat a source area containing trichloroethene (TCE) present as dense nonaqueous phase liquid (DNAPL) was assessed through a laboratory study and a pilot test at Launch Complex 34, Cape Canaveral Air Force Center. The results of microcosm testing indicate that the indigenous microbial community was capable of dechlorinating TCE to ethene if amended with electron donor; however, bioaugmentation with a dechlorinating culture (KB‐1; SiREM, Guelph, Ontario, Canada) significantly increased the rate of ethene formation. In microcosms, the activity of the dechlorinating organisms in KB‐1 was not inhibited at initial TCE concentrations as high as 2 mM. The initially high TCE concentration in ground water (1.2 mM or 155 mg/L) did not inhibit reductive dechlorination, and at the end of the study, the average concentration of ethene (2.4 mM or 67 mg/L) was in stoichiometric excess of this initial TCE concentration. The production of ethene in stoichiometric excess in comparison to the initial TCE concentration indicates that the bioremediation treatment enhanced the removal of TCE mass (either sorbed to soil or present as DNAPL). Detailed soil sampling indicated that the bioremediation treatment removed greater than 98.5% of the initial TCE mass. Confirmatory ground water samples collected 22 months after the bioremediation treatment indicated that chloroethene concentrations had continued to decline in the absence of further electron donor addition. The results of this study confirm that dechlorination to ethene can proceed at the high TCE concentrations often encountered in source areas and that bioremediation was capable of removing significant TCE mass from the test plot, suggesting that enhanced bioremediation is a potentially viable remediation technology for TCE source areas. Dehalococcoides abundance increased by 2 orders of magnitude following biostimulation and bioaugmentation.