Remediation of DNAPL through Sequential In Situ Chemical Oxidation and Bioaugmentation

Site Name:

Launch Complex 34

Location:

Kennedy Space Center, Florida

Period of
Operation:

The demonstration was constructed in 2003 and operated between June 2003 and August 2004.

Cleanup
Type:

Field Demonstration

Technology:
In Situ Bioremediation, In Situ Chemical Oxidation

The test site chosen for the demonstration had been previously used to demonstrate the viability of In Situ Chemical Oxidation (ISCO) as a source treatment technology. This demonstration was conducted to determine whether In Situ Bioremediation (ISB) would serve as a suitable post-ISCO secondary polishing technology. Details about the demonstration are provided below:

  • The demonstration included three operational phases:
    1. Baseline phase with groundwater circulation alone conducted at a constant groundwater velocity.
    2. Biostimulation phase with the addition of electron donor (ethanol) to increase the activity of the indigenous microorganisms and stimulate dechlorination of trichloroethene (TCE).
    3. Bioaugmentation phase with the addition of electron donor and KB-1™ (a bacterial consortium containing Dehalococcoides species).
  • Each phase operated long enough to allow a near steady-state rate of TCE removal to be established.
  • The existing ISCO treatment system included a series of injection and extraction wells, the aboveground treatment system, process instrumentation, and process control.

  • Cleanup Authority:
    Department of Defense's (DoD) Environmental Security Technology Certification Program (ESTCP)

    Contacts:

    Remedial Project Manager
    Mike Deliz
    Environmental Program Office
    NASA/ JJ-D
    Kennedy Space Center, FL 32899
    Phone: 321-867-6971
    Email: delizmj@ksc.nasa.gov

    Project Director
    Dave Major
    GeoSyntec Consultants
    130 Research Lane, Suite 2
    Guelph, Ontario, Canada N1G 5G3
    Phone: 519-822-2230, Ext. 232
    Email: dmajor@geosyntec.com

    Technical Lead
    Eric Hood
    GeoSyntec Consultants
    130 Research Lane, Suite 2
    Guelph, Ontario, Canada N1G 5G3
    Phone: 519-822-2230, Ext. 225
    Email: ehood@geosyntec.com

    Field Study Leader
    Leah MacKinnon
    GeoSyntec Consultants
    130 Research Lane, Suite 2
    Guelph, Ontario, Canada N1G 5G3
    Phone: 519-822-2230, Ext. 246
    Email: LmacKinnon@geosyntec.com

    Associate Professor
    Brent Sleep
    University of Toronto Department of Civil Engineering
    35 St. George Street Toronto,
    Ontario, Canada M5S 1A4
    Phone: 416-978-3005
    Email: sleep@enviro.civ.utoronto.ca

    Contracting Officer's Representative (COR)
    Lance Hansen
    U.S. Army Engineer Research and Development Center
    13909 Halls Ferry Road
    Vicksburg, MS, 39180
    Phone: 601-634-3750
    Email: lance.d.hansen@erdc.usace.army.mil

    Environmental Restoration Program Manager
    Andrea Leeson
    ESTCP Office
    901 Stuart Street, Suite 303
    Arlington, VA 22203
    Phone: 703-696-2118
    Email: andrea.leeson@osd.mil

    Contaminants:
    Trichloroethene (TCE)

    Waste Source:
    Activities conducted at the former launch facility resulted in the presence of TCE DNAPL in the groundwater at the site.

    Type/Quantity of Media Treated:
    Soil (12,500 cubic feet (ft3) of soil containing approximately 370 kilograms (kg) of TCE)

    Purpose/Significance of Application:
    The primary purpose of the field demonstration was to assess the technical feasibility of sequentially applying ISCO using permanganate and enhanced ISB in treatment of TCE; to evaluate the effect of this sequential treatment approach on the overall cost and performance of the treatment; and to determine the point of transition from ISCO to ISB in the treatment phase.

    Regulatory Requirements/Cleanup Goals:
    The primary goals of the demonstration were to achieve a decrease in TCE concentrations with rapid and complete degrade to ethene and to demonstrate that the technology results in significant post-ISCO microbial activity. Performance objectives for the demonstration included the following:

    • Increased microbial biomass compared to the baseline treatment phase.
    • Increased mass flux from DNAPL during treatment after amendment with electron donor and after bioaugmentation compared to the baseline treatment phase.
    • Reduced DNAPL mass compared to the baseline treatment phase.

    Results:
    Following the completion of the demonstration and 12 months after the system was shutdown, a final round of groundwater sampling was conducted at the site in August 2005. Technical problems caused by biofouling and several hurricanes made it challenging to meet all of the performance objectives, which resulted in the demonstration being terminated sooner than anticipated. A summary of the results is presented below:

    • Significant microbial activity was observed throughout the demonstration as evidenced by rapid ethanol fermentation and sulfate reduction. Organisms present during the baseline phase (post-ISCO) did not dechlorinate TCE. However, dechlorination of TCE to ethene was observed during both the biostimulation and bioaugmentation phases.
    • No significant increase was observed in TCE mass flux after the biostimulation and bioaugmentation phases. This was attributed to potential limitation of mass transfer of DNAPL by manganese dioxide precipitates formed during earlier ISCO treatment using potassium permanganate at the site. However, the increase in the mass flux of TCE dechlorination products was found to be greater than for TCE alone. The limited duration of the demonstration made it challenging to conclusively assess the DNAPL mass reduction using sequential ISCO and ISB.
    • Following biostimulation and for the duration of the demonstration, an increase was observed in the TCE degradation rate to form daughter products cis-dichloroethene (cis-DCE), vinyl chloride (VC), and ethene. TCE concentrations decreased significantly during the demonstration and were nondetect in the post-demonstration samples.

    Cost Factors:
    The limited cost assessment indicated there was a significant cost and schedule advantage for the sequential treatment strategy when compared to pump and treat, or the use of ISCO alone (assuming a reasonable mass flux enhancement can be achieved during ISB). The unit costs incurred for the demonstration are likely higher than unit costs for full-scale implementation because fixed costs associated with the demonstration and the full-scale implementation are comparable, while a full-scale implementation would treat a greater volume and mass than the demonstration. In addition, this field demonstration included an extensive monitoring effort and the implementation of a groundwater recirculation system.

    The total cost of the demonstration was $843,000, with unit costs of $2,381 per cubic meter (m3) of soil and $2,280 per kilogram of TCE.

    Description:
    This field demonstration was conducted at Launch Complex 34, an unused launch facility at the Kennedy Space Center (KSC) in Florida. Adjacent to the Engineering Support Building (ESB) at the demonstration sites, there is an extensive trichloroethene (TCE) dense non-aqueous phase liquid (DNAPL) source present in groundwater. During an in situ chemical oxidation (ISCO) demonstration in 1999, 942,985 gallons of a potassium permanganate solution was injected into a 75 foot by 50 foot test plot to treat the DNAPL source. This demonstration was conducted to assess the technical feasibility of coupling the ISCO source treatment conducted in 1999 with in situ bioremediation (ISB) as a secondary remediation approach to address residual DNAPL at the site. The pilot test area for the 2003/2004 ISCO/ISB demonstration was located within the previous ISCO demonstration plot. A preliminary site investigation conducted in December 2002 indicated the presence of residual DNAPL at the site. Based on 2002 soil sampling results, concentrations of TCE in soil exceeded 10,800 milligrams per kilogram (mg/kg) at the pilot test area.

    Construction of the ISB system began in 2003 and ISB system operated between June 2003 and August 2004. The demonstration was conducted in three operational phases: (1) baseline phase, using groundwater circulation alone, started on December 8, 2003; (2) biostimulation phase with the addition of the electron donor, started on March 1, 2004; and (3) bioaugmentation phase, where the test plot was bioaugmented with KB-1™, a bacterial consortium containing Dehalococcoides species, on April 15, 2004. The demonstration was discontinued in August 2004 (sooner than anticipated) due to several hurricanes and biofouling issues. This resulted in several performance objectives not being met. Following the completion of the demonstration, a final round of groundwater samples was collected from the onsite monitoring wells in August 2005, 12 months after system shutdown. Over the duration of the demonstration, TCE concentrations decreased significantly to non-detect levels. The addition of electron donor resulted in the biodegradation of TCE to cis-dichloroethene (DCE) and additional dechlorination occurred flowing the bioaugmentation phase resulting in the formation of vinyl chloride and to a lesser extent ethane. Despite these results, the limited duration of the demonstration made it challenging to conclusively assess the DNAPL mass reduction using sequential ISCO and ISB.