Bioremediation as a Full-Scale Remedy for a Trichlorethene-Contaminated Source Area and Diffuse Plume
Bioremediation as a Full-Scale Remedy for a Trichlorethene-Contaminated Source Area and Diffuse Plume
Presented on Monday, May 5, 2014
The US EPA is completing a full-scale remedial action for a trichloroethene (TCE) source area and diffuse plume using bioremediation at the Bountiful/Woods Cross Operable Unit 1 Site in Utah. The site includes a high-concentration source area, with solvent concentrations as high as approximately 80 parts per million, and a diffuse plume that stretches approximately one-half mile downgradient. The contamination is present within the shallow aquifer, consisting of interbedded sands, silts, clays, and gravels. Initially, a pilot study was completed at the site to select the most appropriate amendment for stimulating reductive dechlorination. The selected remedy includes injection of emulsified oil into the subsurface to stimulate bioremediation; use of emulsified oil provides a long-term source of carbon (up to two years), while also enhancing mass transfer of contaminants from the non-aqueous phase into the groundwater. The source area remedy includes flooding the subsurface through injection into a grid-pattern of permanent injection wells, while the downgradient plume remedy includes injection into rows of injection wells (biobarriers). Advanced characterization using a membrane-interface probe was completed to identify areas requiring treatment.
Initial injections in the source area and first biobarrier were completed in late 2008, with a second injection completed in 2010. Reductive dechlorination was established within the source area within nine months after initial injections were completed, and complete destruction of groundwater contaminants was achieved within approximately three years after initial injections, with the exception of two hot spots. Targeted treatment of the hot spots has continued, with periodic injections of a sodium lactate solution to increase degradation rates of TCE and its daughter products. The downgradient biobarriers were installed in 2011, with injections completed during the summers of 2011 and 2013. Results indicate that substantial progress has been made in remediating contaminants in the diffuse plume using the biobarriers.
Nathan Smith
Environmental Management Division, CDM Smith, Denver, CO
Nathan Smith is a senior project manager and environmental scientist specializing in bioremediation of chlorinated solvents and mining-influenced water.
Sam Garcia
Superfund Region 8, US EPA, Denver, CO
Steve Garcia is a Remedial Project Manager with the Superfund Division of EPA Region 8. He has managed numerous Superfund sites, including multiple sites contaminated with chlorinated solvents.
Ryan Wymore, P.E.
CDM Smith Inc., Denver, CO
Ryan Wymore is a principal environmental engineer with CDM Smith in Denver, Colorado, where he serves as the company’s environmental remediation market leader. He has spent the last 15 years specializing in innovative groundwater remediation technologies. He also serves as the administrator for CDM Smith’s Research and Development Program. Wymore joined ITRC in 2002, and has had membership on seven technical teams. He holds a B.S. in Biological Systems Engineering from the University of Nebraska-Lincoln, and an M.S. in Civil/Environmental Engineering from the University of Idaho.
Kent Sorenson, Ph.D., PE
Environmental Management Division, CDM Smith, Denver, CO
Kent Sorenson is a Senior Vice President of CDM Smith, providing technical expertise in remediation technologies. He has developed and/or demonstrated innovative site characterization and remediation technologies in the U.S., Europe, and Asia, and is a senior technical reviewer for more than 100 government, private, and international sites.
Neil Smith, P.E.
CDM Smith Inc., Denver, CO
Neil Smith is an environmental engineer located in the Denver office of CDM Smith. He has 11 years of experience in site characterization, engineering design, and remedial action implementation on a wide variety of environmental projects. He currently focuses on implementation of innovative strategies and technologies for remediation of groundwater, surface water, and soils. Smith holds a B.S. in Engineering (Civil Specialty) from the Colorado School of Mines and an M.S. in Environmental Engineering from the University of Colorado at Boulder.
Mario Robles
Superfund Region 8, US EPA, Denver, CO
Mario Robles is a Remedial Project Manager with the EPA Region 8 Superfund program. He has managed numerous Superfund projects, including sites contaminated with chlorinated solvents, and abandoned mine sites.