Diagnostic Tools for Integrated In Situ Air Sparging Pilot Tests

Abstract

In situ air sparging (IAS) pilot test procedures have been developed that provide rapid, on-site information about IAS performance. The standard pilot test consists of six activities conducted to look for indicators of infeasibility and to characterize the air distribution to the extent necessary to make design decisions about IAS well placement. In addition, safety hazards that need to be addressed prior to full-scale design are identified. Two additional pilot test activities are described in those cases where air distribution must be more precisely defined. The test activities include both chemical tests (tracking contaminant concentrations, dissolved oxygen and tracers) and physical tests (air flow rate and injection pressure, groundwater pressure response).

Helium Tracer Tests for Assessing Contaminant Vapor Recovery and Air Distribution During In Situ Air Sparging

“…In some cases it is possible that no helium will return to the well due to the presence of continuous layers. The presence of these layers should also be detectable by monitoring groundwater pressure during IAS startup and shutdown (Johnson et al, 2001b). Therefore, it is recommended that the helium recovery test be conducted in conjunction with transient groundwater pressure transducer measurements at start-up.…”

“…• After the transient start-up period (usually this is a few hours or less and can be determined on a sitespecific basis using the transient pressure transducer response test described in Johnson et al, 2001b), helium is blended into the injection air to readily measurable concentrations (e.g., about 5% by volume). • After approximately 5 minutes, and before 15 to 20 minutes, all the vadose zone soil-gas sampling points are sampled and concentrations of the tracer gas are measured and recorded along with the time of measurement/sampling.…”

“…These data provide an indication of the spatial extent and directionality of the air distribution below the water table; information that can be critical for decisions about IAS well spacing. Helium tracer tests, along with transient pressure transducer measurements (Johnson et al, 2001b), are easily incorporated into short-term IAS pilot testing procedures Downloaded by [University of Arizona] at 06:33 07 June 2016 (Johnson et al, 2001). They can also be used for fullscale system diagnosis and optimization.…”

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

“…An alternative or supplementary approach is an indirect estimation of both, IAS range and efficiency, by using artificial or naturally occurring partitioning tracers. In previous studies artificial gas tracers such as SF 6 (Johnson et al, 2001) or helium (Berkey et al, 2003) have been suggested for approaching the problem. However, laboratory analysis for SF 6 or helium is not trivial either.…”

Remediation of Petroleum-contaminated Sites through Simulation of a DPVE-aided Cleanup Process: Part 2. Remediation Design

“…During the past decade, many approaches were undertaken for site remediation techniques design, which mainly included site installation, construction design through site investigation, numerical modeling (USEPA, 1997;Christ et al, 1999;Miller et al, 2000;Johnson et al, 2001;McGovern et al, 2002;Liu et al, 2003;Maqsood et al, 2004;Liu, 2005) and site operation strategy design through mathematical optimization (Sawyer et al, 1995;Rizzo and Dougherty, 1996;Mylopoulos et al, 1999;Huang et al, 2003). Only a few approaches have been reported on how to screen efficient remediation techniques for the sites to answer the questions such as what remediation technologies are suitable and cost-effective for a contaminated site (Medd et al, 1993;Loncar et al, 1994;Brendon, 1995;WTIC, 1997;Lamberti and Nissi, 2005).…”