14    DEVELOPMENT OF AN ALTERNATIVE DESIGN
APPROACH FOR SVE/BIOVENTING SYSTEMS
Todd P. Swingle, Engineer
Parsons Engineering Science, Inc.
Winter Park, Florida 32822
INTRODUCTION
Typical SVE/Bioventing design approaches include determination of the soil gas permeability
and other design parameters using the modified field drawdown method based upon pilot test
data developed from a single vapor extraction well (VEW). However, there are cases where detailed design is required that this sort of analysis does not adequately support the design requirements. As a result, an alternative method for designing SVE/bioventing systems has been developed.
The need for an alternative method of design was realized at a site where a pilot test was originally conducted using a 4-inch diameter VEW. Due to the site's shallow groundwater conditions
and the observed screen blockage due to upwelling, the pilot test VEW could not achieve a satisfactory radius of influence (response of 0.5 inches water vacuum) with the existing VEW design.
Therefore, the VEWs and the air flow used in the full-scale system required design outside the
range of the pilot test data.
An empirical approach based upon fluid flow properties and head loss relationships was developed and utilized to design the full-scale SVE system. This method accounts for specific VEW
responses and reduces the analysis to a solvable matrix of two variables versus four required by
the drawdown method. Based upon this analysis, a full-scale system incorporating 6-inch VEWs
and a redesigned screen configuration was installed at the site. Monitoring of the full-scale system indicates that it is operating within its requirements and consistent with the predictions of
the empirical design approach.
Based upon the success of this system design at the original site, data from additional pilot
tests have been analyzed utilizing this methodology to verify its applicability at sites with varying conditions. Analysis with additional data has supported the general relationships that were
developed at the original site. The benefit of this approach is that data analysis is reduced to a
solvable matrix of equations that does not require that the pilot test fully encompass the design
case. Therefore, this alternative design approach is extremely beneficial in situations where pilot
test equipment or VEW design limitations do not yield data that encompass the operating point
desired for the full-scale system. However, the simplicity of the calculation utilized by this approach leads to its use in applications where pilot test data does encompass the responses desired
for the full-scale system.
PILOT TESTING
Although pilot testing for various bioventing and SVE systems may include a wide variety of
objectives, one commonality is air permeability testing for the purpose of defining the radius of
influence (ROI), well design criteria, and blower requirements. The need for an alternative
method for analyzing this data was realized during pilot testing at the Cummins Southeastern
Power, Inc. (CSPI) facility in Hialeah Gardens, Florida. The pilot testing system at the CSPI site
consisted of one 4-inch diameter vertical vent well (VW), three soil gas monitoring points
(MPs), and a 2-horsepower regenerative blower and related instrumentation. The primary test
conducted was a soil gas permeability test.
51st Purdue Industrial Waste Conference Proceedings. 1996. Ann Arbor Press. Inc.. Chelsea, Michigan 48118.
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