v>EPA
                   United States
                   Environmental Protection
                   Agency
                   Solid Waste and
                   Emergency Response
                   5403W
EPA510-F-93-021
October 1993
Soil  Remediation  For
UST Sites
In  Situ  Soil  Vapor
Extraction
                    In situ soil vapor extraction (SVE) is a technique for
                    removing contaminants from unsaturated soils. The
                   technique draws fresh air into the ground with a vacuum
                   pump. The air brings the contaminants to the surface,
                   where they can be treated and safely discharged.

                   In situ soil vapor extraction is most effective in
                   coarse-grained soils such as sand and gravel. It requires a
                   minimum 5-foot-thick unsaturated zone of soil. This
                   technique can be used in conjunction with air sparging,
                   ground-water pumping, or bioremediation systems.

                   This technique is able to treat large volumes of soil
                   effectively and with minimal  disruption to business
                   operations. It also can remove contamination from near
                   or under fixed structures.
                      Petroleum Types And Constituents

                      • Fresh and weathered gasoline and diesel

                      • Volatile organic compounds (VOCs) such as
                       benzene, toluene, ethylbenzene, and xylene
                       (BTEX); and semivolatile organic compounds
                       (SVOCs)
          SSS^OTECTON
               ,TEXAS 75202

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In Situ Soil Vapor Extraction
Advantages
limitations
System
Components
Wastestream
Treatment
Parameters to
Monitor1
Cleanup Levels
and Timing2
Costs5
• Effectively treats large volumes (>1,000 cu yd) of soil
• Removes contamination near or under fixed structures
• Causes minimal disruption to business operations
• Removes volatile contaminants from the zone of water
table fluctuation
• Effectiveness limited in heterogeneous soils or soils with
high clay or organic content
• Airflow may not contact all parts of soil
• Leaves residual constituents in soil
• Might require air discharge permits
• Vertical or horizontal extraction wells
• Trenches
• Vacuum blower or pump
• Injection and passive inlet wells
• Aboveground vapor treatment equipment (optional)
• Vapor treatment options (if needed):
• Vapor phase biofilter
• Granulated activated carbon
• Internal combustion engine
• Catalytic oxidation unit
• Thermal incinerator
• Vapor concentration
• Airflow rate
• Can remove 90% of volatile organic compounds (VOCs)
and semivolatile organic compounds (SVOCs)
• For an ideal site3, 90% in 6 months to 1 year
• For an average site4, 90% in 6 months to 3 years
• Longer time required for heterogeneous soils and less
volatile constituents
• For an ideal site3, $40,000 to $120,000
• For an average site4, $100,000 to $150,000
• Vapor treatment costs can drastically affect total costs
  Parameters to monitor" are for performance purposes only; compliance monitoring parameters vary by state.
3An 'ideal site" assumes no delays in corrective action and a relatively homogeneous, permeable subsurface.
4An "average ste" assumes minimal delays in corrective action and a rtKXleratelyheterogeneais and pemeabte subsurface.
'Costs include equipment, and operation and maintenance.

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