&EHV
                  United States
                  Environmental Protection
                  Agency
                  Solid Waste and
                  Emergency Response
                  5403W
EPA510-F-93-023
October 1993
Soil Remediation  For
UST Sites
Ex  Situ  Bioremediation:
Biomounding
                    Ex situ bioremediation—biomounding—is a technique
                    for removing biodegradable contaminants from
                  excavated mounds of soil Nutrients are added to the soil
                  mounds, which are often several feet high, to facilitate
                  bioremediation. Aeration conduits and irrigation systems
                  are constructed in the mound.

                  Biomounding is most appropriate for shallow
                  contamination sites that cover a large horizontal area.
                  This is a low-maintenance technique that requires a
                  relatively short treatment time. Biomounding also
                  provides better control over aeration, moisture,
                  nutrient levels, and soil texture than other methods.
                     Petroleum Types And Constituents

                     • Fresh or weathered gasoline, diesel, jet fuel,
                       kerosene, motor oil, heavy fuel ofl, lubricating oils,
                       and crude oils

                     • Volatile organic compounds (VOCs) such as
                       benzene, toluene, ethylbenzene, and xylene (BTEX);
                       residual semivolatUe organic compounds (SVOCs)
                       such as polynuclear aromatic hydrocarbons; and
                       nonvolatile constituents

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Ex Situ Bioremediation: Biomounding
Advantages
limitations
System
Components
Wastestream
Treatment
Parameters to
Monitor1
Cleanup Levels
and Timing2
Costs5
• Degrades semivolatile organic compounds (SVOCs) and
nonvolatile organic compounds
• Requires low maintenance
• Entails a relatively short treatment time
• Enhances control and management of aeration, moisture,
nutrients, and soil texture
• Can use treated soil as backfill
• Targets only biodegradable constituents
• Must excavate soil and remove debris
• Requires sufficient nutrients, moisture, active indigenous
microbial population, and pH of 6-9 to degrade contaminants
• Plastic liner
• Gravel and slotted pipe to provide air to mound
• Nutrients
• Blower
• Soil vapor sampling probes
• Irrigation system (optional)
• Plastic cover (optional)
• Vapor treatment equipment (optional)
• Vapor treatment options (might be needed for high
concentrations of contaminants):
• Granulated activated carbon
• Internal combustion engine
• Catalytic oxidation unit
• Thermal incinerator
• Vapor concentration
• Airflow rate
• Soil contaminant concentration
• Microbial population
• Soil pH, moisture, and nutrients
• Leachate analysis (optional)
• Treats > 90% of biodegradable constituents
• For an ideal site3, ~90% in 6 months to 18 months
• For an average site4, ~90% in 6 months to 2 years
• Longer time required to degrade heavier hydrocarbons
• For an average site4, $80,000 to $125,000 ($80 to $125/cu yd)
• Unit costs generally decrease as soil volume increases
 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 sW assumes mhimaJ delays in corrective action arrianxxierater/Merco^neousaridpeimeablesitsurface.
^Costs Include equipment, and operation and maintenance.

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