Expedited soil remediation employing soil vapor extraction and bioventing at Castle Air Force Base
- Jacobs Engineering Group Inc., Sacramento, CA (United States)
Soil vapor extraction (SVE) involves in-situ removal and treatment of volatile organic compounds (VOCs) from the vadose zone. An SVE system includes vent wells screened in the areas of highest contamination, a piping network connecting the vent wells to a SVE treatment unit, blower(s), and a treatment unit. Typical treatment units include granular activated carbon, catalytic oxidation (catox), thermal oxidation and internal combustion (IC) engines. The type of treatment unit selected is a function of the characteristics of the incoming vapor stream. The blower(s) apply vacuum to selected vent wells, resulting in propagation of a pressure gradient some distance from the wells. This is known as the radius of influence. The zone of remediation within this radius of influence is the distance from the well where sufficient flow velocity exists such that timely clean up of VOCs from the vadose zone can occur. Bioventing is most effective in removing petroleum hydrocarbons with less than 10 carbon chains (C10+). Bioventing involves passive or active injection of air into the subsurface, thus promoting the natural biodegradation of residual petroleum hydrocarbons. Passive injection involves opening vent wells to the atmosphere. Active injection is performed by connecting blowers to vent wells, or the existing piping manifold, and injecting air. Bioventing is most effective in promoting natural biodegradation of residual hydrocarbons in compounds with more than C10+ carbon chains. Factors effecting bioventing performance include: (1) Microorganisms (capable of producing enzymes that can degrade the contamination), (2) Energy source (carbon), (3) Electron acceptor (oxygen), (4) Soil moisture, (5) pH, (6) Nutrients, (7) Soil temperature, and (8) Absence of compounds toxic to microorganisms.
- OSTI ID:
- 474054
- Report Number(s):
- CONF-960804--Vol.2
- Country of Publication:
- United States
- Language:
- English
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