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Dual Auger Rotary Steam Stripping at DOE's Pinellas Northeast Site, Largo, Florida

Site Name:

Pinellas Northeast Site


Largo, Florida

Period of

December 1996 through April 1997


Demonstration (ITRD Technology Demonstration)


In-Situ Fixation, Inc. (ISF)
Chandler, Arizona

In Situ Air and Steam Stripping

- ISF dual auger system consists of a Caterpillar 245D trackhoe modified to operate two, 35-ft long, hollow kelly bars with 5-ft diameter augers
- Air and/or steam injected through hollow kelly bars while augers drill into subsurface, to liberate VOCs
- Catalytic oxidation unit and acid-gas scrubber were used to treat the extracted VOCs
- 48 treatment holes drilled to a depth of approximately 32 feet
- Technology focused on treating saturated silty sands (below the water table) contaminated with high concentrations of VOCs (500-5,000 ppm

Cleanup Authority:

Regulatory Point of Contact:
EPA Region 4 and State: Florida Department of Environmental Protection
Additional Contact:
David Ingle, Site Management
DOE/GJO Environmental Restoration Program Manager
(813) 541-8943

- Chlorinated solvents and volatiles - nonhalogenated 1,1-dichloroethane, 1,1-DCE, benzene, ethylbenzene, 1,2-DCE, methylene, chloride, toluene, TCE, tetrachloroethene, vinyl chloride, total xylenes, and chloromethane
- Concentrations ranging from 500-5,000 ppm
- DNAPL suspected to occur as an immiscible phase

Waste Source:
Leakage of solvents or resins from drum/container storage

Type/Quantity of Media Treated:
Soil and Groundwater

- Water table present approximately 3-4 feet below ground surface
- Soils consist of saturated beach-type silty sands with permeabilities ranging between 10-3 to 10-5 cm/s
- Approximately 2,000 yd3 of soil treated

Purpose/Significance of Application:
Demonstration of in situ air stripping technology used to supplement an ongoing system of pump and treat with air stripping

Regulatory Requirements/Cleanup Goals:
The objective of this demonstration was to evaluate the performance of the ISF dual auger system in treating contaminated soil and groundwater.

- Demonstrated ability to remove large amounts of contaminants from soil and groundwater in a treatment column
- Removed an average of 77% of the VOCs in the groundwater and soil, and reduced the maximum contaminant concentrations by an average of 71%
- Treatment of over 2,000 yd3 of soil and groundwater and the removal of approximately 1,200 pounds of VOCs

Cost Factors:
Total cost of remediation project was $981,251, including:

- Preproject operation visit - $2,400
- Mobilization and preparatory work - $95,000
- Monitoring, sampling, testing, and analysis - $59,000
- Physical treatment - $773,651 (equipment, labor, supplies and materials, and fuel)
- Disposal - $200 (hydraulic oil)
- Demobilization - $51,000

The Pinellas STAR Center operated from 1956 to 1994, manufacturing neutron generators and other electronic and mechanical components for nuclear weapons under contract to the U.S. Department of Energy (DOE) and its predecessor agencies. The Northeast Site is associated with the location of a former waste solvent staging and storage area. In the late 1950s to the late 1960s an existing swampy area at the site was used to dispose drums of waste and construction debris.

A field demonstration using a dual auger rotary steam stripping technology was conducted at the site from December 1996 through April 1997. The demonstration was part of a program at the Pinellas STAR Center to evaluate several innovative remediation technologies that could enhance the cost or performance of the existing pump and treat system. In the demonstration, air and/or steam was injected through hollow kellys while the augers drill into the subsurface, liberating VOC contamination during the churning and mixing of the soil. This study identified operational issues, such as mechanical problems, catalyst overheating, and fugitive emissions that required system adjustments and operational changes. These issues slowed the progress of the remediation effort, but the system was overall very effective in liberating large quantities of VOCs from the site soil and groundwater. During the 3-month operating period, 48 auger holes were drilled to a depth of approximately 32 ft below land surface, resulting in treatment of approximately 2,000 yd3 of the planned 10,000 yd3 treatment volume. Overall, approximately 1,200 lbs of VOCs were removed from the soil and groundwater in the holes treated in this project.

The cost of this remediation project was $981,251, with most of the costs being equipment operating costs. The operational costs of the ISF system ranged from $50/yd3 to $400/yd3 of treated soil and groundwater, or about $300/lb to $500/lb of contaminant removed. The ISF system was able to meet many of the performance evaluation criteria; however, the off-gas treatment capacity of the catalytic oxidation unit along with initial operational problems slowed the system's expected treatment rates for the site.