Technology:
Low Temperature Thermal Desorption
- Direct-fired rotating dryer that heated the soil to between 580 and 750°F using a hot air stream
- Propane gas was used to heat the air stream, and the organic constituents in the soil were desorbed in the dryer through contact with the heated air
- Off-gas treatment included a cyclone/baghouse system; a low pressure drop Venturi air scrubber; and vapor-phase carbon adsorption
- A vacuum of 0.10 to 0.18 inches of water was maintained throughout the process train
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Cleanup Authority:
CERCLA -- Remedial Action
- ROD signed June 28, 1991
EPA Remedial Project Manager:
Derek Matory
U.S. EPA Region 4
345 Courtland Street, NE
Atlanta, GA 30365
Telephone: (404) 562-8800
Fax: (404) 562- 8788
E-mail: matory.derek@epa.gov | Additional Contacts:
George Harvell
Memphis Environmental Center
2603 Corporate Avenue, Suite 100
Memphis, TN 38132
Telephone: (901) 345-1788
Fax: (901) 398-4719
Paul Sadler
Senior Project Engineer
Focus Environmental, Inc.
9050 Executive Park Drive
Knoxville, TN 37923
(423) 694-7517
E-mail: psadler@focusenv.com |
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Contaminants:
Pesticides and Metals
- Maximum concentrations during remedial investigation: chlordane (390 mg/kg surface and 120 mg/kg subsurface); endrin (70 mg/kg surface and 20 mg/kg subsurface); pentachlorophenol (130 mg/kg surface and 9.5 mg/kg) subsurface; arsenic (370 mg/kg surface) |
Waste Source:
Leaks and spills of pesticides during blending and packaging operations; process wastewater discharged to drainage ditches at the site |
Type/Quantity of Media Treated:
Soil - 41,431 tons
- Soils primarily silty sands with an average moisture content of 17 wt%
- pH of soil - 6.8 |
Purpose/Significance of Application:
Application of low temperature thermal desorption to treat pesticide-contaminated soil |
Regulatory Requirements/Cleanup Goals:
- Cleanup goals for organics were: chlordane (3.3 mg/kg); heptachlor (0.3 mg/kg); pentachlorophenol (0.635 mg/kg); endrin (0.608 mg/kg); heptachlor expoxide (0.2 mg/kg)
- Cleanup goal for arsenic initially established at 25 mg/kg in ROD; changed to 100 mg/kg in ESD. All treated soil with a total arsenic concentration > 100 mg/kg was to be disposed of off-site. Any treated soil with total arsenic concentrations > 100 mg/kg and leachable arsenic > 5mg/L (determined by the toxicity characteristic leaching procedure) was required to be identified as hazardous waste and stabilized prior to disposal off-site
- Emission standards for the unit were total hydrocarbons (500 ppmv); particulates (0.08 gr/dscf); and system removal efficiency (> 95%) |
Results:
- A total of 84 batches of soil (41,431 tons) were treated
- All but six batches of soil met the cleanup goals for the organics on the first pass through the system
- Three batches exceeded the cleanup levels and were retreated and met the cleanup goals.
- An additional three batches were slightly above the cleanup levels for total chlordane. Based on the concentrations, EPA determined that the batches were not required to be retreated
- One batch of treated soil did not meet the 100 mg/kg limit for arsenic and was shipped offsite for disposal in a Subtitle C landfill; however, because the TCLP level for arsenic was below the 5 mg/L limit, solidification/stabilization prior to off-site disposal was not required
- Compliance with the emissions standards was verified during the performance test. The unit met all emissions standards during the three test runs, achieving a system removal efficiency >99.999% |
Cost Factors:
- Total project cost was $5,586,376 including $4,356,244 in costs directly associated with the thermal treatment
- Treatment costs included $4,293,893 in capital costs and $62,351 in O&M costs
- The calculated unit cost for this application was $105 per ton, based on 41,431 tons of soil treated |
Description:
The Arlington Blending and Packaging Superfund site, located in Arlington, Tennessee, is a 2.3 acre site that was used for the formulation and packaging of pesticides and herbicides from 1971 to 1978. Chemicals handled at the facility included the pesticides endrin, aldrin, dieldrin, chlordane, heptachlor, lindane, methyl parathion, and thimet as well as solvents and emulsifiers used in the formulation operations. Leaks and spills of chemicals occurred during these operations and process wastewater was discharged to drainage ditches at the site. The site was placed on the National Priorities List (NPL) in July 1987. A remedial investigation (RI), begun in 1988, determined that the main areas of soil contamination at the site were located around and beneath the process buildings. The ROD, signed in 1991, specified excavation of contaminated soil and treatment on site using thermal desorption.
Smith's low temperature thermal aeration (LTTA) process was used to treat the contaminated soil at the site. The unit included a direct-fired rotating dryer that heated the soil using a hot air stream. The heated soil was discharged from the rotary dryer to an enclosed pugmill where it was quenched with water to cool and rehumidify the soil. The treated soil was then sampled, and based on the results, backfilled on site or stabilized and shipped off-site for disposal. A total of 41,431 tons of contaminated soil in 84 batches were treated during this application. All but six batches of soil met the cleanup goals for the organics on the first pass through the system. Three batches exceeded the cleanup levels and were retreated. Three additional batches slightly exceeded the cleanup goal for total chlordane. EPA determined, based on the concentrations, that the batches did not have to be retreated. Following confirmation that the cleanup goals had been met, treated soil was backfilled at the site. Only one batch of treated soil did not meet the total arsenic limit and was shipped offsite for disposal in a Subtitle C landfill.
The original estimate for the soil excavation was 10,000 tons, based on the results from field-based screening using the Drexil method. Subsequent verification analyses indicated that the results from this method were not accurate. The site was recharacterized, using immunoassay sampling (results confirmed to be accurate by an off-site laboratory), and an additional 30,000 tons of soil requiring excavation were identified. The use of immunoassay sampling saved time by providing real time results (versus 5 to 6 day turnaround time for an off-site laboratory). |
