Hydraulic Tomography Implementation Considerations at a Recalcitrant Environmental Site

Thursday, 18 December 2014: 4:00 PM
Chak Hau M Tso1, Chin Man W Mok2, Tian-Chyi J Yeh1, Walter A Illman3 and Yemia Hashimoto4, (1)University of Arizona, Tucson, AZ, United States, (2)GSI Environmental Inc., Houston, TX, United States, (3)University of Waterloo, Waterloo, ON, Canada, (4)AMEC Oakland, Oakland, CA, United States
Hydraulic Tomography (HT) is a robust aquifer characterization method that is capable of providing high-resolution mapping of hydraulic conductivity and specific storage distributions or tomograms. This method is particularly cost-effective to recalcitrant sites where existing pump-and-treat system and monitoring network can be utilized. The high-resolution tomograms generated can provide critical information for targeted in-situ remediation of potential source zones and optimization of existing remediation strategies. In addition, zones for potential back diffusion can be identified.

Conducting HT surveys in operating pump-and-treat sites with complex hydrogeologic conditions requires special considerations. The design of the experiment has to be compatible to site-specific constraints. For example, a minimum total pumping rate may have to be met for the treatment facility to function. Many of the existing monitoring wells may not have been designed for HT surveys and have very long screen intervals. Using our current work at a Department of Defense site with more than twenty candidate extraction and injection wells, as well as over a hundred available monitoring wells as an example, we discuss our implementation strategy, and the HT analysis modifications to cope with these constrains. Lessons learnt from this work provide guidance on future implementation considerations of HT at recalcitrant environmental sites.