HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Zhang, Y. Articles by Benson, S. M. Search for Related Content PubMed Articles by Zhang, Y. Articles by Benson, S. M. GeoRef GeoRef Citation Agricola Articles by Zhang, Y. Articles by Benson, S. M. Related Collections Carbon Sequestration Other Forage Crops Soil Hydrology

SPECIAL SECTION: RESEARCH ADVANCES IN VADOSE ZONE HYDROLOGY THROUGH SIMULATIONS WITH THE TOUGH CODES

Vadose Zone Remediation of Carbon Dioxide Leakage from Geologic Carbon Dioxide Sequestration Sites

Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720
^* Corresponding author (yqzhang{at}lbl.gov)

Received 2 March 2004.

In the unlikely event that CO₂ leakage from deep geologic CO₂ sequestration sites reaches the vadose zone, remediation measures for removing the CO₂ gas plume may have to be undertaken. Carbon dioxide leakage plumes are similar in many ways to volatile organic compound (VOC) vapor plumes, and the same remediation approaches are applicable. We present here numerical simulation results of passive and active remediation strategies for CO₂ leakage plumes in the vadose zone. The starting time for the remediation scenarios is assumed to be after a steady-state CO₂ leakage plume is established in the vadose zone, and the source of this plume has been cut off. We consider first passive remediation, both with and without barometric pumping. Next, we consider active methods involving extraction wells in both vertical and horizontal configurations. To compare the effectiveness of the various remediation strategies, we define a half-life of the CO₂ plume as a convenient measure of the CO₂ removal rate. For CO₂ removal by passive remediation approaches such as barometric pumping, thicker vadose zones generally require longer remediation times. However, for the case of a thin vadose zone where a significant fraction of the CO₂ plume mass resides within the high liquid saturation region near the water table, the half-life of the CO₂ plume without barometric pumping is longer than for somewhat thicker vadose zones. As for active strategies, results show that a combination of horizontal and vertical wells is the most effective among the strategies investigated, as the performance of commonly used multiple vertical wells was not investigated.

Abbreviations: NAPL, nonaqueous phase liquid • SVE, soil vapor extraction • VOC, volatile organic compound