Permeable Reactive Barrier
-- The field demonstration consisted of a one-time injection of emulsified oil substrate (EOS®) and chase water to create a 50-ft long permeable reactive barrier (PRB).
-- Approximately 110 gallons of EOS® and 2,070 gallons of chase water were injected into the subsurface.
-- The PRB was located approximately 50 ft upgradient of an existing interceptor trench.
-- Groundwater was extracted from the interceptor trench, treated using an air stripper, and re-injected using an upgradient infiltration gallery.
Maryland Dept. Environmental Hazardous Waste Program
Waste Management Administration
1800 Washington Blvd, Ste. 645
Baltimore, MD 21230-1719
Robert C. Borden, P.E.
3722 Benson Drive
Raleigh, NC 27609
Naval Facilities Engineering Service Center
1100 23rd Avenue, Code 411
Port Hueneme, CA 93043
-- Explosives/propellants: perchlorate: 3,100 to 20,000 µg/L
-- Volatiles-halogenated: 1,1,1-TCA: 5,700 to 17,000 µg/L; 1,1-DCA: 7 to 62 µg/L; chloroethane: <5 to <20 µg/L; 1,1-DCE: 270 to 1,200 µg/L; PCE: 25 to 110 µg/L; TCE: 28 to 210 µg/L; cis-1,2-DCE: 5.5 to 10 µg/L; trans-1,2-DCE: <5 to <20 µg/L; vinyl chloride <5 to <20 µg/L; ethane: 0.16 to 4.28 µg/L; ethene: 0.04 to 1.94 µg/L
Former lagoon that received ammonium perchlorate and waste solvent.
Type/Quantity of Media Treated:
-- The shallow aquifer (5 to 15 ft below ground surface). Approximately 405,000 gallons of groundwater was treated.
Purpose/Significance of Application:
The primary objective of the project was to evaluate the cost and performance of an EOS® PRB to control the migration of perchlorate plumes at the Site.
Regulatory Requirements/Cleanup Goals:
National Primary Drinking Water Regulations and the Maryland Department of the Environment Generic Numeric Cleanup Standards for Groundwater. Also, a reduction of perchlorate concentration by 90% was targeted.
-- Perchlorate concentrations were less than 4 µg/L in all of the injection wells within 5 days of injection.
-- 18 months after the injection of EOS, the perchlorate removal rates remained greater than 90 percent of the pre-injection levels in the downgradient wells.
-- 1,1,1-TCA was reduced 94 to 98% twenty feet downgradient of the barrier.
-- The average chlorine number was reduced from 3.0 to 1.5, indicating that biodegradation to less chlorinated daughter products was occurring.
Costs for installing a full-scale PRB was compared to that of adding an ion exchange unit to an existing pump-and-treat system. The breakdown of costs is as follows:
-- Estimated costs for the installation of a full-scale PRB at the site was $38,000, which is equivalent to $19 per square foot of barrier or $0.02 per gallon treated. The estimated capital cost for ion exchange was $50,000 and $17,000 annual O&M.
-- The 30-year life cycle costs for installing an emulsified oil PRB are estimated to be $161,400 compared to $383,600 for adding an ion exchange unit to the existing pump-and treat system.
A permeable reactive barrier (PRB) field demonstration was conducted at a confidential site in Maryland to remediate mixed perchlorate and 1,1,1-trichloroethane (TCA) in a groundwater plume. The demonstration was conducted in 2003 and monitoring was conducted for 18 months.
The demonstration consisted of a one-time injection of EOS® and chase water to create a 50-ft long PRB. The PRB was located about 50 ft upgradient from an existing interceptor trench. Groundwater was extracted from the interceptor trench, treated using air stripping, and then re-injected using an upgradient infiltration gallery.
EOS® injection resulted in substantial reductions in perchlorate and 1,1,1-TCA concentration within and downgradient of the PRB. Costs for the demonstration were not provided but estimated costs for the installation of a full scale PRB at the site were provided. The estimated initial costs for installation were $38,000. The 30-year cycle costs for were estimated to be $161,400.