Biodegradation of Dense Non-Aqueous Phase Liquids (DNAPLs) through Bioaugmentation of Source Areas - Dover National Test Site, Dover, Delaware

Site Name:

Dover National Test Site (DNTS)


Dover, Delaware

Period of

April 1, 2001 — May 26, 2005


Pilot Scale


  • This technology demonstration involved the installation of:
    • Three fully screened groundwater extraction wells,
    • Three groundwater injection wells,
    • One groundwater circulation and volatile organic compound (VOC) treatment system with an automated control system,
    • One network of 13 multilevel monitoring well locations, and
    • Four fully screened bioaugmentation wells.
  • The technology was implemented in five operational phases as follows:
    • Phase 1 (Design, Installation and Tracer Testing {Apr 01 to May 02}) - Installation of equipment and performance of tracer test to determine the hydraulic characteristics of the aquifer,
    • Phase 2 (Baseline {May 02 to Feb 03}) - Extraction of contaminated groundwater, removal of VOCs (granular activated carbon [GAC] system), and re-injection of the groundwater into the test cell,
    • Phase 3 (Biostimulation{Mar 03 to Jul 03}) - Similar to Phase 2, but groundwater amended with electron donor (ethanol and sodium lactate) before re-injection,
    • Phase 4 (Bioaugmentation{Jul 03 to Mar 05}) - Similar to Phase 3, but with the test cell bioaugmented with KB-1, and
    • Phase 5 (Post-Bioaugmentation {March 05 to May 05}) - The source zone was flushed with groundwater.

Cleanup Authority:
Department of Defense (DoD)


Carmen A. Lebrón
Project Manager/Technical Lead
Navy Facilities Engineering Service Centre
1100 23rd Avenue
Port Hueneme, CA 93043
Phone: 805-982-1616
Fax: 805-982-4304

Timothy McHale
Dover AFB Site Coordinator
Air Force Research Laboratory (AFRL)
Building 909, Arnold Drive Extended
P.O. Box 02063
Dover Air Force Base, DE 19902
Phone: 302-677-4147
Fax: 302-677-4100

Dave Major
Project Director/Principal
Geosyntec Consultants
130 Research Lane, Suite 2
Guelph, Ontario, Canada
N1G 5G3
Phone: 519-822-2230, Ext. 232
Fax: 519-822-3151

Andrea Leeson
Environmental Restoration Program Manager
901 N. Stuart St., Ste. 303
Arlington, VA 22203-1853
Phone: 703-696-2118
Fax: 703-696-2114

Tetrachloroethene (PCE)

Waste Source:
Dover Air Force Base operated as a coastal patrol base and an operational training base for combat training of fighter pilots under the U.S. Army Air Corps.

Type/Quantity of Media Treated:
Groundwater (quantity not documented)

Purpose/Significance of Application:
The purpose of this demonstration was to evaluate the performance of bioaugmentation, an in situ remediation process that can stimulate the rate of biodegradation, of PCE. Data collection focused on the performance and cost-effectiveness of the proposed treatment system compared to current treatment methods.

Regulatory Requirements/Cleanup Goals:
The primary goal of this demonstration was to increase the degradation rate of PCE following bioaugmentation, measure extent of dehalogenation, duration of remediation, and reduction in DNAPL mass greater than base case treatment.

Results from the demonstration include the following:

  • A significant increase in PCE degradation was observed following the baseline (phase 2) and post-bioaugmentation (phase 5) phases of the project;
  • A significant increase in ethane generation was observed following the decrease in PCE concentration during both bioaugmentation (phase 4) and post-bioaugmentation (phase 5);
  • A large decrease in PCE mass flux was observed following biostimulation (phase 3, [56 g/day as PCE and more than 98% of the mass extracted was as PCE]) and following post-bioaugmentation (5 g/day as PCE with PCE comprising less than 20% of the total mass extracted).

Cost Factors:
The total costs for this demonstration was $850,000 and the unit cost was estimated to be $11,000 per kilogram of PCE addressed.

The Dover National Test Site (DNTS) at Dover Air Force Base (DAFB) covers approximately 3.5 acres of unused open area in the northwest corner of the base. The DAFB was originally leased to the U.S. Army Air Corps to be used as a coastal patrol base. Through the years, the base was changed from an airfield to an operational training base for fighter pilots. The base was deactivated in September of 1946, and was only periodically used after that date.

This demonstration focused on the process of bioaugmentation and its ability to dechlorinate chlorinated ethenes and convert them to more biodegradable forms. The technology installation at the site consisted of three fully screened groundwater extraction and three groundwater injection wells, a groundwater circulation system, a volatile organic compound (VOC) treatment system, and a network of monitoring and bioaugmentation wells. Samples were collected from the extraction wells on a weekly basis and data was collected from multilevel piezometers on a quarterly basis. The demonstration consisted of 5 operational phases: design, installation and tracer testing, baseline, biostimulation, bioaugmentation, and post-bioaugmentation. The demonstration occurred over a period of 5 years, beginning in 2001. Sampling/monitoring schedules and dates varied based on the sample location and analytes reported.

The results of the demonstration show that biological systems can be applied to promote enhanced dissolution of PCE DNAPL. A cost assessment for this demonstration is included in the report.