Remediation Technologies Screening Matrix, Version 4.0 4.8 Soil Vapor Extraction
(In Situ Soil Remediation Technology)
  Description Synonyms Applicability Limitations Site Information Points of Contact
Data Needs Performance Cost References Vendor Info. Health & Safety
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>>3.2 In Situ Physical/Chemical Treatment

      >>4.8 Soil Vapor Extraction
Introduction>> Vacuum is applied through extraction wells to create a pressure/concentration gradient that induces gas-phase volatiles to be removed from soil through extraction wells. This technology also is known as in situ soil venting, in situ volatilization, enhanced volatilization, or soil vacuum extraction.

Description:

Figure 4-8:
Typical In Situ Soil Vapor Extraction System
Soil vapor extraction (SVE) is an in situ unsaturated (vadose) zone soil remediation technology in which a vacuum is applied to the soil to induce the controlled flow of air and remove volatile and some semivolatile contaminants from the soil. The gas leaving the soil may be treated to recover or destroy the contaminants, depending on local and state air discharge regulations. Vertical extraction vents are typically used at depths of 1.5 meters (5 feet) or greater and have been successfully applied as deep as 91 meters (300 feet). Horizontal extraction vents (installed in trenches or horizontal borings) can be used as warranted by contaminant zone geometry, drill rig access, or other site-specific factors.

For the soil surface, geomembrane covers are often placed over soil surface to prevent short circuiting and to increase the radius of influence of the wells.

Ground water depression pumps may be used to reduce ground water upwelling induced by the vacuum or to increase the depth of the vadose zone. Air injection is effective for facilitating extraction of deep contamination, contamination in low permeability soils, and contamination in the saturated zone (see Treatment Technology Profile 4.32, Air Sparging).

The duration of operation and maintenance for in situ SVE is typically medium- to long-term.

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Synonyms:

In situ soil venting; In situ volatilization; Enhanced volatilization.
DSERTS Code: M11 (Soil Vapor Extraction).

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Applicability:

The target contaminant groups for in situ SVE are VOCs and some fuels. The technology is typically applicable only to volatile compounds with a Henry's law constant greater than 0.01 or a vapor pressure greater than 0.5 mm Hg (0.02 inches Hg). Other factors, such as the moisture content, organic content, and air permeability of the soil, will also affect in situ SVE's effectiveness. In situ SVE will not remove heavy oils, metals, PCBs, or dioxins. Because the process involves the continuous flow of air through the soil, however, it often promotes the in situ biodegradation of low-volatility organic compounds that may be present.

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Limitations:

Factors that may limit the applicability and effectiveness of the process include:
  • Soil that has a high percentage of fines and a high degree of saturation will require higher vacuums (increasing costs) and/or hindering the operation of the in situ SVE system.
  • Large screened intervals are required in extraction wells for soil with highly variable permeabilities or stratification, which otherwise may result in uneven delivery of gas flow from the contaminated regions.
  • Soil that has high organic content or is extremely dry has a high sorption capacity of VOCs, which results in reduced removal rates.
  • Exhaust air from in situ SVE system may require treatment to eliminate possible harm to the public and the environment.
  • As a result of off-gas treatment, residual liquids may require treatment/disposal. Spent activated carbon will definitely require regeneration or disposal.
  • SVE is not effective in the saturated zone; however, lowering the water table can expose more media to SVE (this may address concerns regarding LNAPLs).

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Data Needs:

A detailed discussion of these data elements is provided in Subsection 2.2.1 (Data Requirements for Soil, Sediment, and Sludge). Data requirements include the depth and areal extent of contamination, the concentration of the contaminants, depth to water table, and soil type and properties (e.g., structure, texture, permeability, and moisture content).

Pilot studies should be performed to provide design information, including extraction well, radius of influence, gas flow rates, optimal applied vacuum, and contaminant mass removal rates.

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Performance Data:

A field pilot study is necessary to establish the feasibility of the method as well as to obtain information necessary to design and configure the system. During full-scale operation, in situ SVE can be run intermittently (pulsed operation) once the extracted mass removal rate has reached an asymptotic level. This pulsed operation can increase the cost-effectiveness of the system by facilitating extraction of higher concentrations of contaminants. After the contaminants are removed by in situ SVE, other remedial measures, such as biodegradation, can be investigated if remedial action objectives have not been met. In situ SVE projects are typically completed in 1 to 3 years.

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Cost:

The key cost driver information and cost analysis was developed in 2006 using the Remedial Action Cost Engineering and Requirements (RACER) software.

Key Cost Drivers 

        Economy of Scale

o       Quantity of material treated has a large impact

        Soil Type

o       Based on the number of wells required

        Can be radically different if no airflow treatment is required

Cost Analysis

The following table represents estimated costs (by common unit of measure) to apply soil vapor extraction technology at sites of varying size and complexity.   A more detailed cost estimate table which includes specific site characteristics and significant cost elements that contributed to the final costs can be viewed by clicking on the link below.

SOIL TECHNOLOGY:

Soil Vapor Extraction

 

RACER PARAMETERS

Scenario A

Scenario B

Scenario C

Scenario D

Small Site

Large Site

Easy

Difficult

Easy

Difficult

 

 

 

 

 

COST PER CUBIC FOOT

$36

$42

$11

$27

COST PER CUBIC METER

$1,275

$1,485

$405

$975

COST PER CUBIC YARD

$944

$1,100

$300

$722

 Detailed Cost Estimate

The cost of in situ SVE is site-specific, depending on the size of the site, the nature and amount of contamination, and the hydrogeological setting (EPA, July 1989). These factors affect the number of wells, the blower capacity and vacuum level required, and the length of time required to remediate the site. A requirement for off-gas treatment adds significantly to the cost. Water is also frequently extracted during the process and usually requires treatment prior to disposal, further adding to the cost.

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References:


Treatment Technologies for Site Cleanup: Annual Status Report (ASR), Tenth Edition, EPA 542-R-01-004

Innovative Remediation Technologies:  Field Scale Demonstration Project in North America, 2nd Edition

Remediation Technology Cost Compendium - Year 2000

Treatment Experiences at RCRA Corrective Actions, December 2000, EPA 542-F-00-020

Abstracts of Remediation Case Studies, Volume 4,  June, 2000, EPA 542-R-00-006

Guide to Documenting and Managing Cost and Performance Information for Remediation Projects - Revised Version, October, 1998, EPA 542-B-98-007

MTBE Treatment Case Studies presented by the USEPA Office of Underground Storage Tanks.

Battelle Memorial Institute, 1995. ReOpt. V3.1, by Battelle Memorial Institute for DOE under Contract DE/AC06/76RLO 1830.

California Base Closure Environmental Committee (CBCEC), 1994. Treatment Technologies Applications Matrix for Base Closure Activities, Revision 1, Technology Matching Process Action Team, November, 1994.

EPA, 1989. Terra Vac, In Situ Vacuum Extraction System, EPA RREL, Applications Analysis Report, Cincinnati, OH, EPA Report EPA/540/A5-89/003.

EPA, 1989. Terra Vac Vacuum Extraction, EPA RREL, series includes Technology Evaluation, Vol. I, EPA/540/5-89/003a, PB89-192025; Technology Evaluation, Vol. II, EPA/540/A5-89/003b; Applications Analysis, EPA/540/A5-89/003; Technology Demonstration Summary, EPA/540/S5-89/003; and Demonstration Bulletin, EPA/540/M5-89/003.

EPA, 1990. State of Technology Review: Soil Vapor Extraction System Technology, Hazardous Waste Engineering Research Laboratory, Cincinnati, OH, EPA/600/2-89/024.

EPA, 1991. AWD Technologies, Inc. Integrated Vapor Extraction and Stream Vacuum Stripping, EPA RREL, series includes Applications Analysis, EPA/540/A5-91/002, PB89-192033, and Demonstration Bulletin, EPA/540/M5-89/003.

EPA 1991. Guide for Conducting Treatability Studies Under CERCLA: Soil Vapor Extraction, OERP, Washington, DC, EPA Report EPA/540/2-91/019A.

EPA, 1991. In-Situ Soil Vapor Extraction Treatment, Engineering Bulletin, RREL, Cincinnati, OH, EPA/540/2-91/006.

EPA, 1991. Soil Vapor Extraction Technology Reference Handbook, EPA, RREL, Cincinnati, OH, T.A. Pederson and J.T. Curtis, Editors, EPA/540/2-91/003.

EPA, 1992. Evaluation of Soil Venting Application, EPA/540/S-92/004; NTIS: PB92-232362.

EPA, 1997. Analysis of Selected Enhancements for Soil Vapor Extraction, EPA OSWER, EPA/542/R-97/007.

EPA, 1997. Best Management Practices (BMPs) for Soil Treatment Technologies: Suggested Operational Guidelines to Prevent Cross-media Transfer of Contaminants During Clean-UP Activities, EPA OSWER, EPA/530/R-97/007.

Federal Remediation Technologies Roundtable, 1995. Remediation Case Studies: Bioremediation,  EPA/542/R-95/002.

Federal Remediation Technologies Roundtable, 1995. Remediation Case Studies: Groundwater Treatment, EPA/542/R-95/003.

Federal Remediation Technologies Roundtable, 1995. Remediation Case Studies: Soil Vapor Extraction, EPA/542/R-95/004.

Federal Remediation Technologies Roundtable, 1997. Remediation Case Studies: Soil Vapor Extraction and Other In Situ Technologies, EPA/542/R-97/009.

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: In Situ Soil Treatment Technologies (Soil Vapor Extraction, Thermal Processes), EPA/542/R-98/012

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: Groundwater Pump and Treat (Chlorinated Solvents), EPA/542/R-98/013

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: Groundwater Pump and Treat (Nonchlorinated Solvents), EPA/542/R-98/014

Federal Remediation Technologies Roundtable, 1998. Remediation Case Studies: Innovative Groundwater Treatment Technologies, EPA/542/R-98/015.

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Site Information:

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Points of Contact:

General FRTR Agency Contacts

Technology Specific Web Sites:

Government Web Sites

Non Government Web Sites

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Vendor Information:

A list of vendors offering In Situ Physical/Chemical Soil Treatment  is available from EPA REACH IT which combines information from three established EPA databases, the Vendor Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and Characterization Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give users access to comprehensive information about treatment and characterization technologies and their applications.

Government Disclaimer

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Health and Safety:

Hazard Analysis

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