SOIL VAPOR EXTRACTION SYSTEM DESIGN: A CASE STUDY COMPARING VACUUM AND POREGAS VELOCITY CUTOFF CRITERIA
Soil vapor extraction (SVE) systems are typically designed based on the results of a vadose zone pumping test (transient or steady state) using a pressure criteria to establish the zone of influence (ZOI). A common problem associated with pressure based SVE design is overestimating the ZOI of the extraction well. The vacuum criteria commonly used to establish the boundary of the ZOI results in large areas with very low pore velocities and thus long cleanup times. As a result, design strategies based upon critical pore gas velocity (CPGV) have increased in popularity. The CPGV is used in an effort to loosely incorporate the effects of mass transfer limitations into the design of SVE systems. Critical pore gas velocity designs use a minimum pore gas velocity rather than minimum vacuum to identify the extent of the treatment zone of an SVE system. The CPGV is typically much larger than the pore gas velocity at the perimeter of vacuum based (ZOI) designs resulting in shorter cleanup times. In this paper, we report the results of testing performed at the Savannah River Site (SRS) to determine the influence of a vapor extraction well based upon both a pressure and pore gas velocity design criteria. Results from this testing show that a SVE system designed based upon a CPGV is more robust and will have shorter cleanup times due to increased flow throughout the treatment zone. Pressure based SVE design may be appropriate in applications where soil gas containment is the primary objective; however, in cases where the capture and removal of contaminated soil gas is the primary objective, CPGV is a better design criteria.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC09-96SR18500
- OSTI ID:
- 891649
- Report Number(s):
- WSRC-MS-2006-00328; TRN: US200622%%290
- Country of Publication:
- United States
- Language:
- English
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