In Situ Bimetallic Nanoscale Particle (BNP) treatment (categorized as in situ chemical reduction)
- BNP consists of submicron particles of zero valent iron (Fe0) with a trace coating of palladium (approximately 0.1% by weight) that acts as a catalyst; treatment of contaminants is based on a redox process where the zero valent iron serves as the electron donor
- Pilot test of in situ BNP conducted at Area I; groundwater recirculation initiated one day prior to injection of BNP to enhance in situ mixing and achieve hydraulic control of pilot test area
- BNP pressure injection performed from February 5-7, 2002, using three injection points; piston pump used with open probe rods using a bottom up injection procedure
- Injection point -1 (IP-1):
- String of probe rods retracted from 65 to 43 feet bgs at injection rate of approximately 2.5 gpm- IP-2:
- Total of approximately 2,260 liters of 1.4 g/L BNP suspension (average concentration) injected
- String of probe rods retracted from 65 feet below grade to ground surface at injection rate of approximately 2.5 gpm; due to problems with grout pump (likely from pressure build-up) rods had to be pulled up to ground surface- IP-3:
- Total of approximately 2,070 liters of 1.5 g/L BNP suspension (average concentration) injected
- String of probe rods retracted from 65 to 34 feet below grade at injection rate of approximately 2.5 gpm - Groundwater monitoring performed on day 1, 7, 14, and 28 following BNP injection and analyzed for VOCs, chloride, iron, and geochemical parameters
- Total of approximately 2,315 liters of 1.4 g/L BNP suspension (average concentration) injected
Remedial Project Manager
U.S. Environmental Protection Agency
New York, NY 10007 - 1866
Naval Air Engineering Station - Lakehurst
Building 343, Hwy 547
Lakehurst, NJ 08733-5000
PARS Environmental, Inc.
6A South Gold Drive
Robbinsville, NJ 08691
Telephone: (609) 890-7277
Tetrachloroethene (PCE), trichloroethene (TCE), 1,1,1-trichloroethane (1,1,1,-TCA), cis-dichloroethene (cis-DCE), and vinyl chloride.
- Contamination extends vertically 70 feet below groundwater table
- Largest amount of contamination in the zone from 30 to 50 feet below groundwater table
- In February 2000, total volatile organic compound (VOC) concentrations in groundwater approximately 900 µg/L
Various facility operations and releases
Type/Quantity of Media Treated:
Groundwater: 1,800 cubic feet or 13,500 gallons; based on an assumed treatment area of 300 ft2, an impacted groundwater thickness of 20 ft, and porosity of 0.3
- Average hydraulic conductivity of aquifer - 88.31 ft/day
- Estimated hydraulic gradient - 0.002 ft/ft
- Estimated groundwater velocity - 0.59 ft/day
- Geology: unconsolidated sediments characterized as a fairly uniform, brown-yellow, fine to coarse sand; grain size analyses characterized sediments as 0.5 to 5.9% gravel, 85.8 to 93.6% sand, and 5.4 to 8.6% clay; total organic carbon levels ranged from 40 to 800 mg/kg
Purpose/Significance of Application:
Pilot test of in situ BNP injection to treat groundwater contaminated with chlorinated hydrocarbons
Regulatory Requirements/Cleanup Goals:
The primary objective of the pilot test was to assess the feasibility of using BNP to treat chlorinated hydrocarbons in groundwater in Area I at the site. The remedial goal was to reduce, but not completely degrade, chlorinated hydrocarbons in the treatment area. Changes in groundwater chemistry (for example, oxidation-reduction potential (ORP)) following the application of BNP were also evaluated. No specific cleanup goals were identified.
- Results from the BNP pilot test are based on data collected from February 8 to May 6, 2002
- Average reductions of concentrations for PCE, TCE, and cis-DCE in the treatment area were approximately 67% to 87%. The total reduction of VOCs within the treatment area during this period was approximately 74%.
- Within specific wells, reductions were as high as 100% for PCE, 74% for TCE, 89% for cis-1,2-DCE, and 88% for total VOCs
- During the pilot test, ORP levels in groundwater were reduced from a range of +170 to +311 mV to a range of -100 to -400 mV. Reducing conditions were observed two months following the completion of the pilot test.
- Based on the results of the pilot test, a larger scale pilot test of BNP in Area I was recommended
NAES Lakehurst, located in Orange County, New Jersey, is approximately 7,300 acres in size. Groundwater in Area I at the site was determined to be contaminated with chlorinated hydrocarbons, including PCE, TCE, 1,1,1-TCA, and vinyl chloride, with levels of VOCs as high as 900 µg/L. A pilot test of in situ BNP was conducted at the site from February to March 2002. BNP consists of submicron particles of zero valent iron with a trace coating of palladium that acts as a catalyst. The treatment of contaminants using BNP is based on a redox process where the zero valent iron serves as the electron donor. The objective of the pilot test was to assess the feasibility of using BNP to treat chlorinated hydrocarbons in groundwater in Area I at the site, and to evaluate changes in groundwater chemistry following the application of BNP. A BNP-water suspension was injected into the groundwater at three injection points using pressure injection through open probe rods. A total of approximately 7,000 liters of BNP suspension was injected from February 5 to 7, 2002, and groundwater sampling was performed through May 2002.
The average reductions of PCE, TCE, and cis-DCE in the treatment area were approximately 67% to 87% from February 8 to May 6, 2002. The total reduction of VOCs within the treatment area during this period was approximately 74%. ORP data showed that reducing conditions were achieved during the pilot test and two months after completion of the test. Based on these results, a larger scale pilot test of BNP in Area I was recommended. Suggestions for improvement in the larger scale test included increasing the amount of BNP injected into the groundwater by increasing the concentration of the suspension and increasing the number of injection points, and injecting BNP in a grid pattern to create a reaction zone.