U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Treatment Technologies

Direct and Multiphase Recovery

Halogenated Alkenes

Adobe PDF LogoMulti-Phase Extraction: State-of-the-Practice
U.S. EPA, EPA 542-R-99-004, 1999

This report describes the state-of-the-practice for MPE of contaminated soil and groundwater, focusing primarily on the application and use of MPE at sites with halogenated volatile organic compounds (VOCs). MPE is an innovative technology that has the potential to be more cost-effective and to remediate sites more quickly than conventional technologies can.

Case Studies

Paul's Classic Drycleaners, Wisconsin
State Coalition for Remediation of Drycleaners

An unknown quantity of PCE was released to the subsurface soil and groundwater. Soils under the site consist of interbedded clay, silt, and sand to approximately 10 ft followed by sand to approximately 35 ft. Along with other treatment systems, ten high vacuum dual-phase wells were used to address residual and free-phase DNAPL in the vadose and saturated zones. Groundwater and extracted NAPL are treated through an air stripper and a diffused aeration tank.

Randolf's Cleaners & Alterations, Tallahassee, Florida
State Coalition for Remediation of Drycleaners

An unknown quantity of PCE was released to the subsurface soil and groundwater. Groundwater occurs between 45 and 55 ft bgs and soil under the site consists of silty to sandy clay from the surface to 20 ft bgs; silty clay to clay from 20-37 ft bgs; silt and fine-grained sand with some clay from 37-53 ft bgs; silty clay interbedded with silt from 53-80 ft bgs; and weathered limestone interbedded with sandy to plastic clay from 80-156 ft bgs.

Given the low permeability of the subsurface, six 5-inch diameter PVC recovery wells screened from 5-70 ft bgs were installed. One-third horsepower Grundfos submersible pumps were used to lower the water table and recover contaminated groundwater while a vacuum was applied to each well.

Johannsen Cleaners Lebanon, Oregon
Oregon Department of Environmental Quality
See also State Coalition for Remediation of Drycleaners

Johannsen Cleaners began operation in 1955. The facility used PCE for its operations. An unknown quality of PCE has been released to the subsurface. Soils beneath the facility consist of alluvium containing gravel and sand with varying amounts of silt and clay. Shallow soil was excavated to 3 ft from the back of the facility but access was limited. A dual-phase extraction system was installed that consisted of three horizontal vacuum-driven extraction wells installed beneath the southern end of the building.

Mass of Chlorinated Volatile Organic Compounds Removed by Pump-and-Treat, Naval Air Warfare Center, West Trenton, New Jersey, 1996-2010
Lacombe, P.J.
U.S. Geological Survey Scientific Investigations Report 2011-5003, 48 pp, 2011

Pump and Treat (P&T) remediation is the primary technique used to contain and remove TCE and its degradation products from groundwater at the Naval Air Warfare Center, West Trenton, NJ. Three methods were used to determine the masses of TCE, cDCE, and VC removed from groundwater by the P&T system since 1996. Method 1 is based on the flow volume and concentrations in groundwater that entered the P&T building as influent. Method 2 is based on withdrawal volume from each active recovery well and the concentrations in the water samples from each well. Method 3 compares the maximum monthly amount of TCE, cDCE, and VC from Method 1 and Method 2 and then selects the greater of the two values to represent the masses of removed from groundwater each month. To determine the mass of original TCE removed from groundwater, the individual masses of TCE, cDCE, and VC (determined using Methods 1, 2, and 3) were converted to numbers of moles, summed, and converted to pounds of original TCE. P&T monthly reports state that 24,805 lbs of summed TCE, cDCE, and VC were removed from groundwater; however, the simple summing method dramatically underestimates the mass of original solvent removed by the P&T system.