Technology:
Thermal desorption
- Low temperature thermal desorption system owned by Williams Environmental Inc - direct-heated countercurrent rotary dryer fired by a 49 million BTU/hour burner, feed metering unit, baghouse, thermal oxidizer, and control unit that housed the controls, data logger, and analyzers.
- Average system throughput of 43.3 tons/hr
- Residence time - 20 minutes
- Average soil exit temperature - 851 oF
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Cleanup Authority:
CERCLA
- ROD signed June 30, 1989
PRP Contractor:
Bruce Ford
Bechtel Environmental
Millennium Construction Contractors
P.O. Box 4777
Fort McMurry, Alberta, Canada T9H 5G3
E-mail: bford@suncor.com | EPA Contact:
Jon Bornholm
EPA Region 4
61 Forsyth Street, S.W.
Atlanta, GA 30303-8960
Telephone: (404) 562-8820
Fax: (404) 562-8788
E-mail: bornholm.jon@epa.gov |
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Contaminants:
PAHs , arsenic, chromium, benzene |
Waste Source:
Discharges from wood preserving operations |
Type/Quantity of Media Treated:
Soil
- 170,300 tons of soil treated
- Silty clays and sand
- Moisture content <20% (shallow soil); 20% to 40% (deep soil) |
Purpose/Significance of Application:
Thermal desorption of a large volume of soil contaminated with wood preserving chemicals containing PAHs, benzene, and metals |
Regulatory Requirements/Cleanup Goals:
Cleanup goals for soil specified in the ROD:
- Total carcinogenic PAHs (sum of benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, chrysene, dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene.) - 2.5 mg/kg
- Total PAHs (total carcinogenic PAHs plus the sum of acenaphthene, acenaphthalene, anthracene, benzo(g,h,i)perylene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene) - 100 mg/kg
- Benzene - 0.005 mg/kg, arsenic - 94 mg/kg, chromium - 88 mg/kg |
Results:
- With two exceptions, all soil met the cleanup goals after initial treatment in the desorber
- Approximately 1,106 tons of soil failed to meet the cleanup goal for benzene, and were retreated to meet the cleanup goal
- Of the 378 piles of treated soil, only one pile had a level of chromium, 89.3 mg/kg, that exceeded the cleanup goal of 88 mg/kg. According to the RPM, EPA allowed the contractor to backfill this material without further treatment. |
Cost Factors:
- The total cost for the thermal treatment application at this site was $9,888,575, including $1,800,529 in capital cost and $8,088,046 on O&M costs
- The unit cost for this application was $58/ton based on treating 170,300 tons of soil |
Description:
The Cape Fear Superfund Site is located on 41 acres in Fayetteville, North Carolina. The site was operated as a wood preserving facility from 1953 to 1983, first using a creosote process and, starting in 1970, using a copper-chromated-arsenate (CCA) process. Liquid and sludge wastes generated by both of these processes were pumped into a drainage ditch and an unlined lagoon. Investigations at the site by EPA and the State of North Carolina showed that soil at the site was contaminated with polycyclic aromatic hydrocarbons (PAHs), benzene, and metals including arsenic and chromium. A Record of Decision (ROD), signed in June 1989, specified excavation and soil washing to address the soil contamination from the drainage ditch and unlined lagoon. However, initial soil washing operations did not meet the cleanup goals for carcinogenic PAHs. and EPA made the decision to implement the contingent remedy, low temperature thermal desorption.
The thermal treatment system used for this application was a low temperature thermal desorption system owned by Williams Environmental Services, Inc. A demonstration test was performed July 20 - 22, 1998 during which 1,900 cubic yards of soil were treated. Full-scale thermal desorption was conducted from July 1998 to April 1999 during which 170,300 tons of soil were treated. The total costs for the thermal treatment application $9,888,575 ($58/ton of soil treated). This completed project involved the largest quantity of soil treated using thermal desorption the U.S. at the time the project was performed. |
