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Superfund Innovative Technology Evaluation (SITE)

Abstract

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Hydrogen Release Compound (HRC) Barrier Application at the North of Basin F Site, Rocky Mountain Arsenal
October 2009

This Innovative Technology Evaluation Report documents the results of a demonstration of the hydrogen release compound (HRC®) barrier technology developed by Regenesis Bioremediation Products, Inc., of San Clemente, California. HRC® is a proprietary, food-quality glycerol polylactate ester that slowly releases lactic acid when injected into groundwater aquifers. The HRC® enhances natural anaerobic degradation of organic contaminants in the groundwater. The technology was evaluated from February 2001 to October 2002 at the North of Basin F site at the Rocky Mountain Arsenal (RMA) in Commerce City, Colorado. The demonstration evaluated the technology's ability to treat groundwater containing contaminants generated during the processing of chemical warfare agents and during commercial production of pesticides.

The technology evaluation was conducted in an alluvial, surficial aquifer consisting of an upper 1- to 3-foot interval of well-graded sand/gravel and a lower 7- to 8-foot interval of unconsolidated sand to poorly cemented sandstone; the aquifer overlays the claystone of the Denver Formation. A 50-foot by 30-foot L-shaped permeable barrier of HRC® was installed; each leg of the barrier consisted of three staggered rows of injection points on 6-foot centers. HRC® was injected from the bottom up using direct-push methods at a dose rate of about 10 pounds per foot over a 10-foot interval (from about 44 to 54 feet below ground surface). A total of 4,200 pounds of HRC® was injected in 42 points. Groundwater samples were collected from an array of monitoring wells to evaluate the technology’s performance. The wells were located upgradient, within, and downgradient from the HRC® barrier.

The primary objective of the technology evaluation was to determine the ability of the technology to significantly reduce the primary contaminants of concern (COC) in the North of Basin F plume study area. The primary COCs consisted of di-isopropylmethylphosphonate (DIMP), chlorophenylmethyl sulfide, chlorophenylmethyl sulfone, dieldrin, dicyclopentadiene (DCPD), chloroform, methylene chloride, and tetrachloroethene (PCE). Benzene, trichloroethene (TCE), 1,2-dibromo-3-chloropropane, and n-nitroso-dimethylamine were evaluated as secondary COCs. Results of the evaluation showed decreasing trends for the following COCs: PCE, TCE, DIMP, DCPD, and benzene. Percent reductions for these COCs were generally in the 50 to 80 percent range at multiple downgradient wells, although higher percent reductions were observed for PCE and DCPD (90 to 95 percent). Downgradient concentrations of PCE, DCPD, and benzene were also reduced over the course of the evaluation to below applicable site-specific remediation goals.

An economic analysis of the HRC® technology indicated that costs can vary considerably and are based on several factors, including the type and scale of the application, contaminant types and levels, regulatory criteria, and various site-specific factors. The estimated cost for the scenario in the economic analysis section of this report, which incorporates actual costs for 1 year of treatment under conditions similar to those encountered at RMA, was approximately $0.55 per gallon of treated water. Over a longer period of time, this unit cost would likely be significantly reduced.

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Randy Parker

Risk Mangement Research | Air and Climate Change Research | Water Research | Ecosystems Restoration Research | Land Risk Management Research | Technology: Sustainable Technologies Research, Environmental Technology Verification Program (ETV), and Technology Assessments

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