Dense Nonaqueous Phase Liquids (DNAPLs)

Thermal Processes: Ex Situ

Halogenated Alkenes

General Resources

Technical Requirements for On-Site Low Temperature Thermal Desorption of Solid Media Contaminated with Hazardous Chlorinated Organics
Interstate Technology and Regulatory Council (ITRC). TD-2, 45 pp, 1997

This document deals with the treatment of solid media contaminated with hazardous organics—chlorinated solvents, chlorinated pesticides, and PCBs—through the application of thermal desorption technologies. The requirements presented in this document are directed toward relatively small, short-term, on-site projects, defined here as projects that process about 20,000 cubic yards or less of contaminated material and operate on site for roughly six months to one year.

Case Studies: Chlorinated Solvents

Application Guide for Thermal Desorption Systems
D. Pal, S. Fann, and S. Wight, Naval Facilities Engineering Service Center.
TR-2090-ENV, 256 pp, 1998

Contains a case study of the American Thermostat Superfund Project, South Cairo, NY. Improper disposal practices involved the dumping of spent PCE and TCE solvents on the grounds, resulted in contamination of the site soil and, shortly thereafter, the groundwater. A low-temperature enhanced volatilization facility (LTEVF), in essence low-temperature thermal desorption, was utilized for remediating the soil. Due to the volume of source zone soil, thermal treatment was performed in two stages: Phase I involved nearly 13,000 CY of soil, and an additional 26,000 CY of soil was treated in Phase II.

Low Temperature Thermal Desorption at Longhorn Army Ammunition Plant, Karnack, Texas
Federal Remediation Technology Roundtable Cost and Performance Database, 2000

Soil/source material excavation and full-scale operation of a low-temperature thermal desorption (LTTD) treatment system was performed between February and December 1997 to address excavated soils containing halogenated volatiles, such as TCE and methylene chloride. A low-temperature catalytic oxidation system was used to treat the LTTD off-gas. After confirming that treated soil met the cleanup criteria, the soil was used as general fill material for landfill caps at two sites at the activity. Demobilization of the treatment system was completed in January 1998, and site restoration was completed by June 1998.

Thermal Desorption at the McKin Company Superfund Site, Gray, Maine
Federal Remediation Technology Roundtable Cost and Performance Database, 1995

Soil at this former waste collection, transfer, storage, and disposal facility was contaminated with halogenated VOCs and petroleum products, including PAHs and aromatic compounds. Soil contamination levels were measured as high as 1,500 mg/kg for TCE, 49 mg/kg for methylene chloride, and 21 mg/kg for xylenes. Several areas of contaminated soil at McKin required on-site thermal desorption treatment, i.e., a VOC-contaminated area and a petroleum-contaminated area. The thermal desorption system included a rotary kiln desorber with offgases treated using a filter, baghouse, scrubber, and carbon adsorption. Thermal desorption of approximately 11,000 cubic yards of soil was completed between July 1986 and April 1987—one of the earliest full-scale applications of thermal desorption to remediate halogenated VOCs at a Superfund site.

Thermal Desorption at the Metaltec Superfund Site, Franklin Borough, New Jersey
Federal Remediation Technology Roundtable Cost and Performance Database, 2001

A thermal desorption system was used at the site to treat soil contaminated with VOCs, with maximum concentrations in soil of 7,600 mg/kg TCE and 6,600 mg/kg 1,2-DCE. The system treated 4,215 cubic yds of contaminated soil to below cleanup goals in less than 2 months, with no soil requiring retreatment.

Thermal Desorption at the Sarney Farm Superfund Site, Amenia, New York
Federal Remediation Technology Roundtable Cost and Performance Database, 2001

The 40-acre Sarney Farm Superfund site holds a five-acre permitted sanitary landfill that operated from 1968 to 1969. During that time, non-permitted industrial wastes and barrels of waste solvents were disposed of in and around the landfill, as well as in trenches around the site. Site investigations indicated that soil and groundwater at the site were contaminated with organics, primarily VOCs (1,2-DCA, 2-butanone, 4-methyl-2-pentanone, chloroform, toluene, TCE, and xylenes). The 1990 ROD specified removal of drums and excavation and on-site treatment of contaminated soil using low temperature thermal desorption for two areas. A total of 10,514 tons of soil was treated from August through December 1997.

Case Studies: PCE

Case Studies: Evaporative Desorption Technology (EDT) Remediation of Chlorinated VOCs in Saturated Bay Mud and Clay Deposits
Brady, P., D.W. Moore, M. Sutton, and P.D. Horton.
Eighth International Conference on Remediation of Chlorinated and Recalcitrant Compounds ( Monterey , CA ; May 2012). Battelle Press, ISBN 978-0-9819730-5-0, Paper B-048, 8 pp, 2012

EDT was used to address elevated concentrations of PCE >50,000 µg/kg and degradation compounds in tight bay mud soil at a former industrial dry cleaning facility located near the margin of San Francisco Bay. EDT is a flameless thermal technology that uses desiccated air for treatment. Excavation and batch treatment powered by a Tier III diesel generator was conducted over a period of two months using two 10-ton soil bins within the trailer-mounted mobile treatment unit, where air temperatures ranged from 900-1,100 degrees F. The effluent vapors were captured in two GAC vessels in series. EDT treatment of the high-concentration source material was followed by enhanced in situ bioremediation to treat the residual PCE mass in the "halo" and groundwater plume outside the treatment area. PCE >50,000 µg/kg was treated to <20 µg/kg, and in most cases <5 µg/kg.

Thermal Desorption at the Rocky Flats Environmental Technology Site, Golden, Colorado
Federal Remediation Technology Roundtable Cost and Performance Database, 2001

Thermal desorption technology was selected to treat contaminated soils from the Mound Site. PCE was the primary VOC, with concentrations as high as 760 mg/kg. A batch process design was selected based on the relatively small volume of soil to be treated, and a desire to minimize size reduction activities because of the presence of radionuclide contamination. This application included several enhancements to the McLaren Hart thermal treatment system, including use of trays to hold the soil instead of placing the soil directly into the ovens, and use of a preheater in the off gas treatment train between the condenser and the HEPA filters to raise the temperature of the offgas leaving the condenser above its dew point. Treated soil samples met the cleanup goals on the first pass, with results below detection limits for all but two batches. These two batches were re-treated and met the goals after re-treatment.

Case Studies: TCE

Thermal Desorption at Letterkenny Army Depot Superfund Site, K Areas, OU 1 Chambersburg, Franklin County, Pennsylvania
Federal Remediation Technology Roundtable Cost and Performance Database, 2000

A 1992 remedial investigation identified elevated levels of TCE, PCBs, metals, and SVOCs in soils in the K areas. A 1991 ROD specified excavation of VOC-contaminated soil and on-site treatment using low temperature thermal desorption. The unit operated from September 1993 to October 1994. A total of 13,986 cubic yards of soil was treated during this application, including 2,620 cubic yards of "black stained" soils that contained heavy oils, greases, and debris.